Zettelstore

0.17.0-dev

// FormatKind specifies the format that is applied to the inline nodes.
type FormatKind int

// Constants for FormatCode
const (
	_            FormatKind = iota
	FormatEmph              // Emphasized text
	FormatStrong            // Strongly emphasized text
	FormatInsert            // Inserted text
	FormatDelete            // Deleted text
	FormatSuper             // Superscripted text
	FormatSub               // SubscriptedText
	FormatQuote             // Quoted text
	FormatMark              // Marked text
	FormatSpan              // Generic inline container
)

func (*FormatNode) inlineNode() { /* Just a marker */ }

// WalkChildren walks to the formatted text.
func (fn *FormatNode) WalkChildren(v Visitor) { Walk(v, &fn.Inlines) }

		return false, nil
	}
	return false, err
}

func createFullCredential(zid id.Zid, ident, credential string) []byte {
	var buf bytes.Buffer
	buf.Write(zid.Bytes())
	buf.WriteByte(' ')
	buf.WriteString(ident)
	buf.WriteByte(' ')
	buf.WriteString(credential)
	return buf.Bytes()
}

	if !ok || subject == "" {
		return nil, ErrNoIdent
	}

	now := time.Now().Round(time.Second)
	sClaim := sx.MakeList(
		sx.Int64(kind),
		sx.String(subject),
		sx.Int64(now.Unix()),
		sx.Int64(now.Add(d).Unix()),
		sx.Int64(ident.Zid),
	)
	return sign(sClaim, a.secret)
}

	"zettelstore.de/z/web/server"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

// BoxWithPolicy wraps the given box inside a policy box.
func BoxWithPolicy(manager auth.AuthzManager, box box.Box, authConfig config.AuthConfig) (box.Box, auth.Policy) {




	pol := newPolicy(manager, authConfig)
	return newBox(box, pol), pol
}

// polBox implements a policy box.
type polBox struct {
	box    box.Box

	return pp.box.CanUpdateZettel(ctx, zettel)
}

func (pp *polBox) UpdateZettel(ctx context.Context, zettel zettel.Zettel) error {
	zid := zettel.Meta.Zid
	user := server.GetUser(ctx)
	if !zid.IsValid() {
		return box.ErrInvalidZid{Zid: zid.String()}
	}
	// Write existing zettel
	oldZettel, err := pp.box.GetZettel(ctx, zid)
	if err != nil {
		return err
	}
	if pp.policy.CanWrite(user, oldZettel.Meta, zettel.Meta) {

func (pp *polBox) Refresh(ctx context.Context) error {
	user := server.GetUser(ctx)
	if pp.policy.CanRefresh(user) {
		return pp.box.Refresh(ctx)
	}
	return box.NewErrNotAllowed("Refresh", user, id.Invalid)
}
func (pp *polBox) ReIndex(ctx context.Context, zid id.Zid) error {
	user := server.GetUser(ctx)
	if pp.policy.CanRefresh(user) {
		// If a user is allowed to refresh all data, it it also allowed to re-index a zettel.
		return pp.box.ReIndex(ctx, zid)
	}
	return box.NewErrNotAllowed("ReIndex", user, zid)
}

// BaseBox is implemented by all Zettel boxes.
type BaseBox interface {
	// Location returns some information where the box is located.
	// Format is dependent of the box.
	Location() string








	// GetZettel retrieves a specific zettel.
	GetZettel(ctx context.Context, zid id.Zid) (zettel.Zettel, error)







	// AllowRenameZettel returns true, if box will not disallow renaming the zettel.
	AllowRenameZettel(ctx context.Context, zid id.Zid) bool

	// RenameZettel changes the current Zid to a new Zid.
	RenameZettel(ctx context.Context, curZid, newZid id.Zid) error

	// CanDeleteZettel returns true, if box could possibly delete the given zettel.
	CanDeleteZettel(ctx context.Context, zid id.Zid) bool

	// DeleteZettel removes the zettel from the box.
	DeleteZettel(ctx context.Context, zid id.Zid) error
}

// WriteBox is a box that can create / update zettel content.
type WriteBox interface {
	// CanCreateZettel returns true, if box could possibly create a new zettel.
	CanCreateZettel(ctx context.Context) bool

	// CreateZettel creates a new zettel.
	// Returns the new zettel id (and an error indication).
	CreateZettel(ctx context.Context, zettel zettel.Zettel) (id.Zid, error)

	// CanUpdateZettel returns true, if box could possibly update the given zettel.
	CanUpdateZettel(ctx context.Context, zettel zettel.Zettel) bool

	// UpdateZettel updates an existing zettel.
	UpdateZettel(ctx context.Context, zettel zettel.Zettel) error
}

// ZidFunc is a function that processes identifier of a zettel.
type ZidFunc func(id.Zid)

// MetaFunc is a function that processes metadata of a zettel.
type MetaFunc func(*meta.Meta)

	// Refresh the box data.
	Refresh(context.Context)
}

// Box is to be used outside the box package and its descendants.
type Box interface {
	BaseBox
	WriteBox

	// FetchZids returns the set of all zettel identifer managed by the box.
	FetchZids(ctx context.Context) (id.Set, error)

	// GetMeta returns the metadata of the zettel with the given identifier.
	GetMeta(context.Context, id.Zid) (*meta.Meta, error)

	// SelectMeta returns a list of metadata that comply to the given selection criteria.
	// If `metaSeq` is `nil`, the box assumes metadata of all available zettel.
	SelectMeta(ctx context.Context, metaSeq []*meta.Meta, q *query.Query) ([]*meta.Meta, error)

	// GetAllZettel retrieves a specific zettel from all managed boxes.
	GetAllZettel(ctx context.Context, zid id.Zid) ([]zettel.Zettel, error)

	// Refresh the data from the box and from its managed sub-boxes.
	Refresh(context.Context) error

	// ReIndex one zettel to update its index data.
	ReIndex(context.Context, id.Zid) error
}

// Stats record stattistics about a box.
type Stats struct {
	// ReadOnly indicates that boxes cannot be modified.
	ReadOnly bool

// ErrStopped is returned if calling methods on a box that was not started.
var ErrStopped = errors.New("box is stopped")

// ErrReadOnly is returned if there is an attepmt to write to a read-only box.
var ErrReadOnly = errors.New("read-only box")

// ErrZettelNotFound is returned if a zettel was not found in the box.
type ErrZettelNotFound struct{ Zid id.Zid }

func (eznf ErrZettelNotFound) Error() string { return "zettel not found: " + eznf.Zid.String() }

// ErrConflict is returned if a box operation detected a conflict..
// One example: if calculating a new zettel identifier takes too long.
var ErrConflict = errors.New("conflict")

// ErrCapacity is returned if a box has reached its capacity.
var ErrCapacity = errors.New("capacity exceeded")

// ErrInvalidZid is returned if the zettel id is not appropriate for the box operation.
type ErrInvalidZid struct{ Zid string }

func (err ErrInvalidZid) Error() string { return "invalid Zettel id: " + err.Zid }

}

// Setup remembers important values.
func Setup(cfg *meta.Meta) { myConfig = cfg.Clone() }

func (*compBox) Location() string { return "" }








func (cb *compBox) GetZettel(_ context.Context, zid id.Zid) (zettel.Zettel, error) {
	if gen, ok := myZettel[zid]; ok && gen.meta != nil {
		if m := gen.meta(zid); m != nil {
			updateMeta(m)
			if genContent := gen.content; genContent != nil {
				cb.log.Trace().Msg("GetZettel/Content")
				return zettel.Zettel{
					Meta:    m,
					Content: zettel.NewContent(genContent(m)),
				}, nil
			}
			cb.log.Trace().Msg("GetZettel/NoContent")
			return zettel.Zettel{Meta: m}, nil
		}
	}
	err := box.ErrZettelNotFound{Zid: zid}
	cb.log.Trace().Err(err).Msg("GetZettel/Err")
	return zettel.Zettel{}, err
}

func (*compBox) HasZettel(_ context.Context, zid id.Zid) bool {
	_, found := myZettel[zid]
	return found
}

				handle(m)
			}
		}
	}
	return nil
}








func (*compBox) AllowRenameZettel(_ context.Context, zid id.Zid) bool {
	_, ok := myZettel[zid]
	return !ok
}

func (cb *compBox) RenameZettel(_ context.Context, curZid, _ id.Zid) (err error) {

	if _, ok := myZettel[curZid]; ok {
		err = box.ErrReadOnly
	} else {
		err = box.ErrZettelNotFound{Zid: curZid}
	}
	cb.log.Trace().Err(err).Msg("RenameZettel")
	return err
}

func (*compBox) CanDeleteZettel(context.Context, id.Zid) bool { return false }

func (cb *compBox) DeleteZettel(_ context.Context, zid id.Zid) (err error) {

	if _, ok := myZettel[zid]; ok {
		err = box.ErrReadOnly
	} else {
		err = box.ErrZettelNotFound{Zid: zid}
	}
	cb.log.Trace().Err(err).Msg("DeleteZettel")
	return err
}

func (cb *compBox) ReadStats(st *box.ManagedBoxStats) {
	st.ReadOnly = true

)

func genLogM(zid id.Zid) *meta.Meta {
	m := meta.New(zid)
	m.Set(api.KeyTitle, "Zettelstore Log")
	m.Set(api.KeySyntax, meta.SyntaxText)
	m.Set(api.KeyCreated, kernel.Main.GetConfig(kernel.CoreService, kernel.CoreStarted).(string))
	m.Set(api.KeyModified, kernel.Main.GetLastLogTime().Local().Format(id.TimestampLayout))
	return m
}

func genLogC(*meta.Meta) []byte {
	const tsFormat = "2006-01-02 15:04:05.999999"
	entries := kernel.Main.RetrieveLogEntries()
	var buf bytes.Buffer

  h1 { font-size:1.5rem;  margin:.65rem 0 }
  h2 { font-size:1.25rem; margin:.70rem 0 }
  h3 { font-size:1.15rem; margin:.75rem 0 }
  h4 { font-size:1.05rem; margin:.8rem 0; font-weight: bold }
  h5 { font-size:1.05rem; margin:.8rem 0 }
  h6 { font-size:1.05rem; margin:.8rem 0; font-weight: lighter }
  p { margin: .5rem 0 0 0 }
  p.zs-meta-zettel { margin-top: .5rem; margin-left: 0.5rem }
  li,figure,figcaption,dl { margin: 0 }
  dt { margin: .5rem 0 0 0 }
  dt+dd { margin-top: 0 }
  dd { margin: .5rem 0 0 2rem }
  dd > p:first-child { margin: 0 0 0 0 }
  blockquote {
    border-left: 0.5rem solid lightgray;

`(@@@@
(html ,@(if lang `((@ (lang ,lang))))
(head
  (meta (@ (charset "utf-8")))
  (meta (@ (name "viewport") (content "width=device-width, initial-scale=1.0")))
  (meta (@ (name "generator") (content "Zettelstore")))
  (meta (@ (name "format-detection") (content "telephone=no")))
  ,@META-HEADER
  (link (@ (rel "stylesheet") (href ,css-base-url)))
  (link (@ (rel "stylesheet") (href ,css-user-url)))
  ,@(ROLE-DEFAULT-meta (current-environment))
  (title ,title))
(body
  (nav (@ (class "zs-menu"))
    (a (@ (href ,home-url)) "Home")
    ,@(if with-auth
      `((div (@ (class "zs-dropdown"))
        (button "User")

      `((div (@ (class "zs-dropdown"))
        (button "New")
        (nav (@ (class "zs-dropdown-content"))
          ,@(map wui-link new-zettel-links)
       )))
    )
    (form (@ (action ,search-url))
      (input (@ (type "text") (placeholder "Search..") (name ,query-key-query) (dir "auto"))))
  )
  (main (@ (class "content")) ,DETAIL)
  ,@(if FOOTER `((footer (hr) ,@FOOTER)))
  ,@(if debug-mode '((div (b "WARNING: Debug mode is enabled. DO NOT USE IN PRODUCTION!"))))
)))

	number   int
	zettel   map[id.Zid]constZettel
	enricher box.Enricher
}

func (*constBox) Location() string { return "const:" }








func (cb *constBox) GetZettel(_ context.Context, zid id.Zid) (zettel.Zettel, error) {
	if z, ok := cb.zettel[zid]; ok {
		cb.log.Trace().Msg("GetZettel")
		return zettel.Zettel{Meta: meta.NewWithData(zid, z.header), Content: z.content}, nil
	}
	err := box.ErrZettelNotFound{Zid: zid}
	cb.log.Trace().Err(err).Msg("GetZettel/Err")
	return zettel.Zettel{}, err
}

func (cb *constBox) HasZettel(_ context.Context, zid id.Zid) bool {
	_, found := cb.zettel[zid]
	return found
}

			cb.enricher.Enrich(ctx, m, cb.number)
			handle(m)
		}
	}
	return nil
}








func (cb *constBox) AllowRenameZettel(_ context.Context, zid id.Zid) bool {
	_, ok := cb.zettel[zid]
	return !ok
}

func (cb *constBox) RenameZettel(_ context.Context, curZid, _ id.Zid) (err error) {

	if _, ok := cb.zettel[curZid]; ok {
		err = box.ErrReadOnly
	} else {
		err = box.ErrZettelNotFound{Zid: curZid}
	}
	cb.log.Trace().Err(err).Msg("RenameZettel")
	return err
}

func (*constBox) CanDeleteZettel(context.Context, id.Zid) bool { return false }

func (cb *constBox) DeleteZettel(_ context.Context, zid id.Zid) (err error) {

	if _, ok := cb.zettel[zid]; ok {
		err = box.ErrReadOnly
	} else {
		err = box.ErrZettelNotFound{Zid: zid}
	}
	cb.log.Trace().Err(err).Msg("DeleteZettel")
	return err
}

func (cb *constBox) ReadStats(st *box.ManagedBoxStats) {
	st.ReadOnly = true

	id.MustParse(api.ZidDependencies): {
		constHeader{
			api.KeyTitle:      "Zettelstore Dependencies",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxZmk,
			api.KeyLang:       api.ValueLangEN,
			api.KeyReadOnly:   api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityPublic,
			api.KeyCreated:    "20210504135842",
			api.KeyModified:   "20230601163100",
		},
		zettel.NewContent(contentDependencies)},
	id.BaseTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Base HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20230510155100",
			api.KeyModified:   "20230827212200",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		zettel.NewContent(contentBaseSxn)},
	id.LoginTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Login Form HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20200804111624",
			api.KeyModified:   "20230527144100",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		zettel.NewContent(contentLoginSxn)},
	id.ZettelTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Zettel HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20230510155300",
			api.KeyModified:   "20231126180500",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		zettel.NewContent(contentZettelSxn)},
	id.InfoTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Info HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20200804111624",
			api.KeyModified:   "20231023152000",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		zettel.NewContent(contentInfoSxn)},
	id.FormTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Form HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,

		zettel.NewContent(contentDeleteSxn)},
	id.ListTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore List Zettel HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20230704122100",
			api.KeyModified:   "20231129112800",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		zettel.NewContent(contentListZettelSxn)},
	id.ErrorTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Error HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20210305133215",
			api.KeyModified:   "20230527224800",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		zettel.NewContent(contentErrorSxn)},
	id.StartSxnZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Sxn Start Code",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20230824160700",
			api.KeyVisibility: api.ValueVisibilityExpert,
			api.KeyPrecursor:  string(api.ZidSxnBase),
		},
		zettel.NewContent(contentStartCodeSxn)},
	id.BaseSxnZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Sxn Base Code",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20230619132800",
			api.KeyModified:   "20231012154500",
			api.KeyReadOnly:   api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
			api.KeyPrecursor:  string(api.ZidSxnPrelude),
		},
		zettel.NewContent(contentBaseCodeSxn)},
	id.PreludeSxnZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Sxn Prelude",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20231006181700",
			api.KeyModified:   "20231019140400",
			api.KeyReadOnly:   api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		zettel.NewContent(contentPreludeSxn)},
	id.MustParse(api.ZidBaseCSS): {
		constHeader{
			api.KeyTitle:      "Zettelstore Base CSS",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxCSS,
			api.KeyCreated:    "20200804111624",
			api.KeyModified:   "20231129112800",
			api.KeyVisibility: api.ValueVisibilityPublic,
		},
		zettel.NewContent(contentBaseCSS)},
	id.MustParse(api.ZidUserCSS): {
		constHeader{
			api.KeyTitle:      "Zettelstore User CSS",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxCSS,
			api.KeyCreated:    "20210622110143",
			api.KeyVisibility: api.ValueVisibilityPublic,
		},
		zettel.NewContent([]byte("/* User-defined CSS */"))},









	id.EmojiZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Generic Emoji",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxGif,
			api.KeyReadOnly:   api.ValueTrue,
			api.KeyCreated:    "20210504175807",
			api.KeyVisibility: api.ValueVisibilityPublic,
		},
		zettel.NewContent(contentEmoji)},
	id.TOCNewTemplateZid: {
		constHeader{
			api.KeyTitle:      "New Menu",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxZmk,
			api.KeyLang:       api.ValueLangEN,
			api.KeyCreated:    "20210217161829",
			api.KeyModified:   "20231129111800",
			api.KeyVisibility: api.ValueVisibilityCreator,
		},
		zettel.NewContent(contentNewTOCZettel)},
	id.MustParse(api.ZidTemplateNewZettel): {
		constHeader{
			api.KeyTitle:                 "New Zettel",
			api.KeyRole:                  api.ValueRoleConfiguration,
			api.KeySyntax:                meta.SyntaxZmk,
			api.KeyCreated:               "20201028185209",
			api.KeyModified:              "20230929132900",
			meta.NewPrefix + api.KeyRole: api.ValueRoleZettel,
			api.KeyVisibility:            api.ValueVisibilityCreator,
		},
		zettel.NewContent(nil)},
	id.MustParse(api.ZidTemplateNewRole): {
		constHeader{
			api.KeyTitle:                  "New Role",
			api.KeyRole:                   api.ValueRoleConfiguration,
			api.KeySyntax:                 meta.SyntaxZmk,
			api.KeyCreated:                "20231129110800",
			meta.NewPrefix + api.KeyRole:  api.ValueRoleRole,
			meta.NewPrefix + api.KeyTitle: "",
			api.KeyVisibility:             api.ValueVisibilityCreator,
		},
		zettel.NewContent(nil)},
	id.MustParse(api.ZidTemplateNewTag): {
		constHeader{
			api.KeyTitle:                  "New Tag",
			api.KeyRole:                   api.ValueRoleConfiguration,
			api.KeySyntax:                 meta.SyntaxZmk,
			api.KeyCreated:                "20230929132400",
			meta.NewPrefix + api.KeyRole:  api.ValueRoleTag,
			meta.NewPrefix + api.KeyTitle: "#",
			api.KeyVisibility:             api.ValueVisibilityCreator,
		},
		zettel.NewContent(nil)},
	id.MustParse(api.ZidTemplateNewUser): {
		constHeader{
			api.KeyTitle:                       "New User",
			api.KeyRole:                        api.ValueRoleConfiguration,
			api.KeySyntax:                      meta.SyntaxNone,
			api.KeyCreated:                     "20201028185209",
			meta.NewPrefix + api.KeyCredential: "",
			meta.NewPrefix + api.KeyUserID:     "",
			meta.NewPrefix + api.KeyUserRole:   api.ValueUserRoleReader,
			api.KeyVisibility:                  api.ValueVisibilityOwner,
		},
		zettel.NewContent(nil)},
	id.MustParse(api.ZidRoleZettelZettel): {
		constHeader{
			api.KeyTitle:      api.ValueRoleZettel,
			api.KeyRole:       api.ValueRoleRole,
			api.KeySyntax:     meta.SyntaxZmk,
			api.KeyCreated:    "20231129161400",
			api.KeyLang:       api.ValueLangEN,
			api.KeyVisibility: api.ValueVisibilityLogin,
		},
		zettel.NewContent(contentRoleZettel)},
	id.MustParse(api.ZidRoleConfigurationZettel): {
		constHeader{
			api.KeyTitle:      api.ValueRoleConfiguration,
			api.KeyRole:       api.ValueRoleRole,
			api.KeySyntax:     meta.SyntaxZmk,
			api.KeyCreated:    "20231129162800",
			api.KeyLang:       api.ValueLangEN,
			api.KeyVisibility: api.ValueVisibilityLogin,
		},
		zettel.NewContent(contentRoleConfiguration)},
	id.MustParse(api.ZidRoleRoleZettel): {
		constHeader{
			api.KeyTitle:      api.ValueRoleRole,
			api.KeyRole:       api.ValueRoleRole,
			api.KeySyntax:     meta.SyntaxZmk,
			api.KeyCreated:    "20231129162900",
			api.KeyLang:       api.ValueLangEN,
			api.KeyVisibility: api.ValueVisibilityLogin,
		},
		zettel.NewContent(contentRoleRole)},
	id.MustParse(api.ZidRoleTagZettel): {
		constHeader{
			api.KeyTitle:      api.ValueRoleTag,
			api.KeyRole:       api.ValueRoleRole,
			api.KeySyntax:     meta.SyntaxZmk,
			api.KeyCreated:    "20231129162000",
			api.KeyLang:       api.ValueLangEN,
			api.KeyVisibility: api.ValueVisibilityLogin,
		},
		zettel.NewContent(contentRoleTag)},
	id.DefaultHomeZid: {
		constHeader{
			api.KeyTitle:   "Home",
			api.KeyRole:    api.ValueRoleZettel,
			api.KeySyntax:  meta.SyntaxZmk,
			api.KeyLang:    api.ValueLangEN,
			api.KeyCreated: "20210210190757",

//go:embed listzettel.sxn
var contentListZettelSxn []byte

//go:embed error.sxn
var contentErrorSxn []byte

//go:embed start.sxn
var contentStartCodeSxn []byte

//go:embed wuicode.sxn
var contentBaseCodeSxn []byte

//go:embed prelude.sxn
var contentPreludeSxn []byte

//go:embed base.css
var contentBaseCSS []byte

//go:embed emoji_spin.gif
var contentEmoji []byte

//go:embed newtoc.zettel
var contentNewTOCZettel []byte

//go:embed rolezettel.zettel
var contentRoleZettel []byte

//go:embed roleconfiguration.zettel
var contentRoleConfiguration []byte

//go:embed rolerole.zettel
var contentRoleRole []byte

//go:embed roletag.zettel
var contentRoleTag []byte

//go:embed home.zettel
var contentHomeZettel []byte

`(article
  (header (h1 ,heading))
  (form (@ (action ,form-action-url) (method "POST") (enctype "multipart/form-data"))
  (div
    (label (@ (for "zs-title")) "Title " (a (@ (title "Main heading of this zettel.")) (@H "ⓘ")))
    (input (@ (class "zs-input") (type "text") (id "zs-title") (name "title") (placeholder "Title..") (value ,meta-title) (dir "auto") (autofocus))))
  (div
    (label (@ (for "zs-role")) "Role " (a (@ (title "One word, without spaces, to set the main role of this zettel.")) (@H "ⓘ")))
    (input (@ (class "zs-input") (type "text") (id "zs-role") (name "role") (placeholder "role..") (value ,meta-role) (dir "auto")
      ,@(if role-data '((list "zs-role-data")))
    ))
    ,@(wui-datalist "zs-role-data" role-data)
  )
  (div
    (label (@ (for "zs-tags")) "Tags " (a (@ (title "Tags must begin with an '#' sign. They are separated by spaces.")) (@H "ⓘ")))
    (input (@ (class "zs-input") (type "text") (id "zs-tags") (name "tags") (placeholder "#tag") (value ,meta-tags) (dir "auto"))))
  (div
    (label (@ (for "zs-meta")) "Metadata " (a (@ (title "Other metadata for this zettel. Each line contains a key/value pair, separated by a colon ':'.")) (@H "ⓘ")))
    (textarea (@ (class "zs-input") (id "zs-meta") (name "meta") (rows "4") (placeholder "metakey: metavalue") (dir "auto")) ,meta))
  (div
    (label (@ (for "zs-syntax")) "Syntax " (a (@ (title "Syntax of zettel content below, one word. Typically 'zmk' (for zettelmarkup).")) (@H "ⓘ")))
    (input (@ (class "zs-input") (type "text") (id "zs-syntax") (name "syntax") (placeholder "syntax..") (value ,meta-syntax) (dir "auto")
      ,@(if syntax-data '((list "zs-syntax-data")))
    ))
    ,@(wui-datalist "zs-syntax-data" syntax-data)
  )
  ,@(if (bound? 'content)
    `((div
      (label (@ (for "zs-content")) "Content " (a (@ (title "Content for this zettel, according to above syntax.")) (@H "ⓘ")))
      (textarea (@ (class "zs-input zs-content") (id "zs-content") (name "content") (rows "20") (placeholder "Zettel content..") (dir "auto")) ,content)
    ))
  )
  (div
    (input (@ (class "zs-primary") (type "submit") (value "Submit")))
    (input (@ (class "zs-secondary") (type "submit") (value "Save") (formaction "?save")))
    (input (@ (class "zs-upload") (type "file") (id "zs-file") (name "file")))
  ))
)

`(article
  (header (h1 "Information for Zettel " ,zid)
    (p
      (a (@ (href ,web-url)) "Web")
      (@H " · ") (a (@ (href ,context-url)) "Context")
      ,@(if (bound? 'edit-url) `((@H " · ") (a (@ (href ,edit-url)) "Edit")))
      ,@(ROLE-DEFAULT-actions (current-environment))

      ,@(if (bound? 'reindex-url) `((@H " · ") (a (@ (href ,reindex-url)) "Reindex")))

      ,@(if (bound? 'rename-url) `((@H " · ") (a (@ (href ,rename-url)) "Rename")))
      ,@(if (bound? 'delete-url) `((@H " · ") (a (@ (href ,delete-url)) "Delete")))
    )
  )
  (h2 "Interpreted Metadata")
  (table ,@(map wui-table-row metadata))
  (h2 "References")

`(article
  (header (h1 ,heading))
  (form (@ (action ,search-url))
    (input (@ (class "zs-input") (type "text") (placeholder "Search..") (name ,query-key-query) (value ,query-value) (dir "auto"))))
  ,@(if (bound? 'tag-zettel)
     `((p (@ (class "zs-meta-zettel")) "Tag zettel: " ,@tag-zettel))
    )
  ,@(if (bound? 'create-tag-zettel)
     `((p (@ (class "zs-meta-zettel")) "Create tag zettel: " ,@create-tag-zettel))
    )
  ,@(if (bound? 'role-zettel)
     `((p (@ (class "zs-meta-zettel")) "Role zettel: " ,@role-zettel))
    )
  ,@(if (bound? 'create-role-zettel)
     `((p (@ (class "zs-meta-zettel")) "Create role zettel: " ,@create-role-zettel))
    )
  ,@content
  ,@endnotes
  (form (@ (action ,(if (bound? 'create-url) create-url)))
      "Other encodings: "
      (a (@ (href ,data-url)) "data")
      ", "
      (a (@ (href ,plain-url)) "plain")

This zettel lists all zettel that should act as a template for new zettel.
These zettel will be included in the ""New"" menu of the WebUI.
* [[New Zettel|00000000090001]]
* [[New Role|00000000090004]]
* [[New Tag|00000000090003]]
* [[New User|00000000090002]]

;;;----------------------------------------------------------------------------
;;; Copyright (c) 2023-present Detlef Stern
;;;
;;; This file is part of Zettelstore.
;;;
;;; Zettelstore is licensed under the latest version of the EUPL (European
;;; Union Public License). Please see file LICENSE.txt for your rights and
;;; obligations under this license.
;;;----------------------------------------------------------------------------

;;; This zettel contains all sxn definitions that are independent of specific
;;; subsystems, such as WebUI, API, or other. It just contains generic code to
;;; be used elsewhere.

;; Constants NIL and T
(defconst NIL ())
(defconst T   'T)

;; Function not
(defun not (x) (if x NIL T))
(defconst not not)

;; defunconst macro to define functions that are bound as a constant.
;;
;; (defunconst NAME ARGS EXPR ...)
(defmacro defunconst (name args . body)
    `(begin (defun ,name ,args ,@body) (defconst ,name ,name)))

;; let macro
;;
;; (let (BINDING ...) EXPR ...), where BINDING is a list of two elements
;;   (SYMBOL EXPR)
(defmacro let (bindings . body)
    `((lambda ,(map car bindings) ,@body) ,@(map cadr bindings)))

;; let* macro
;;
;; (let* (BINDING ...) EXPR ...), where SYMBOL may occur in later bindings.
(defmacro let* (bindings . body)
    (if (null? bindings)
        `((lambda () ,@body))
        `((lambda (,(caar bindings))
                  (let* ,(cdr bindings) ,@body))
                  ,(cadar bindings))))

;; and macro
;;
;; (and EXPR ...)
(defmacro and args
    (cond ((null? args)       T)
          ((null? (cdr args)) (car args))
          (T                  `(if ,(car args) (and ,@(cdr args))))))


;; or macro
;;
;; (or EXPR ...)
(defmacro or args
    (cond ((null? args)       NIL)
          ((null? (cdr args)) (car args))
          (T                  `(if ,(car args) T (or ,@(cdr args))))))

Zettel with role ""configuration"" are used within Zettelstore to manage and to show the current configuration of the software.

Typically, there are some public zettel that show the license of this software, its dependencies, some CSS code to make the default web user interface a litte bit nicer, and the defult image to singal a broken image.

Other zettel are only visible if an user has authenticated itself, or if there is no authentication enabled.
In this case, one additional configuration zettel is the zettel containing the version number of this software.
Other zettel are showing the supported metadata keys and supported syntax values.
Zettel that allow to configure the menu of template to create new zettel are also using the role ""configuration"".

Most important is the zettel that contains the runtime configuration.
You may change its metadata value to change the behaviour of the software.

One configuration is the ""expert mode"".
If enabled, and if you are authorized so see them, you will discover some more zettel.
For example, HTML templates to customize the default web user interface, to show the application log, to see statistics about zettel boxes, to show the host name and it operating system, and many more.

You are allowed to add your own configuration zettel, for example if you want to customize the look and feel of zettel by placing relevant data into your own zettel.

By default, user zettel (for authentification) use also the role ""configuration"".
However, you are allowed to change this.

A zettel with the role ""role"" describes a specific role.
The described role must be the title of such a zettel.

This zettel is such a zettel, as it describes the meaning of the role ""role"".
Therefore it has the title ""role"" too.
If you like, this zettel is a meta-role.

You are free to create your own role-describing zettel.
For example, you want to document the intended meaning of the role.
You might also be interested to describe needed metadata so that some software is enabled to analyse or to process your zettel.

A zettel with role ""tag"" is a zettel that describes specific tag.
The tag name must be the title of such a zettel.

Such zettel are similar to this specific zettel: this zettel describes zettel with a role ""tag"".
These zettel with the role ""tag"" describe specific tags.
These might form a hierarchy of meta-tags (and meta-roles).

A zettel with the role ""zettel"" is typically used to document your own thoughts.
Such zettel are the main reason to use the software Zettelstore.

The only predefined zettel with the role ""zettel"" is the [[default home zettel|00010000000000]], which contains some welcome information.

You are free to change this.
In this case you should modify this zettel too, so that it reflects your own use of zettel with the role ""zettel"".

;;;----------------------------------------------------------------------------
;;; Copyright (c) 2023-present Detlef Stern
;;;
;;; This file is part of Zettelstore.
;;;
;;; Zettelstore is licensed under the latest version of the EUPL (European
;;; Union Public License). Please see file LICENSE.txt for your rights and
;;; obligations under this license.
;;;----------------------------------------------------------------------------

;;; This zettel is the start of the loading sequence for Sx code used in the
;;; Zettelstore. Via the precursor metadata, dependend zettel are evaluated
;;; before this zettel. You must always depend, directly or indirectly on the
;;; "Zettelstore Sxn Base Code" zettel. It provides the base definitions.

;;;----------------------------------------------------------------------------
;;; Copyright (c) 2023-present Detlef Stern
;;;
;;; This file is part of Zettelstore.
;;;
;;; Zettelstore is licensed under the latest version of the EUPL (European
;;; Union Public License). Please see file LICENSE.txt for your rights and
;;; obligations under this license.
;;;----------------------------------------------------------------------------

;; Contains WebUI specific code, but not related to a specific template.

;; wui-list-item returns the argument as a HTML list item.
(defunconst wui-item (s) `(li ,s))

;; wui-table-row takes a pair and translates it into a HTML table row with
;; two columns.
(defunconst wui-table-row (p)
    `(tr (td ,(car p)) (td ,(cdr p))))

;; wui-valid-link translates a local link into a HTML link. A link is a pair
;; (valid . url). If valid is not truish, only the invalid url is returned.
(defunconst wui-valid-link (l)
    (if (car l)
        `(li (a (@ (href ,(cdr l))) ,(cdr l)))
        `(li ,(cdr l))))

;; wui-link takes a link (title . url) and returns a HTML reference.
(defunconst wui-link (q)
    `(a (@ (href ,(cdr q))) ,(car q)))

;; wui-item-link taks a pair (text . url) and returns a HTML link inside
;; a list item.
(defunconst wui-item-link (q) `(li ,(wui-link q)))

;; wui-tdata-link taks a pair (text . url) and returns a HTML link inside
;; a table data item.
(defunconst wui-tdata-link (q) `(td ,(wui-link q)))

;; wui-item-popup-link is like 'wui-item-link, but the HTML link will open
;; a new tab / window.
(defunconst wui-item-popup-link (e)
    `(li (a (@ (href ,e) (target "_blank") (rel "noopener noreferrer")) ,e)))

;; wui-option-value returns a value for an HTML option element.
(defunconst wui-option-value (v) `(option (@ (value ,v))))

;; wui-datalist returns a HTML datalist with the given HTML identifier and a
;; list of values.
(defunconst wui-datalist (id lst)
    (if lst
        `((datalist (@ (id ,id)) ,@(map wui-option-value lst)))))

;; wui-pair-desc-item takes a pair '(term . text) and returns a list with
;; a HTML description term and a HTML description data. 
(defunconst wui-pair-desc-item (p) `((dt ,(car p)) (dd ,(cdr p))))

;; wui-meta-desc returns a HTML description list made from the list of pairs
;; given.
(defunconst wui-meta-desc (l)
    `(dl ,@(apply append (map wui-pair-desc-item l))))

;; wui-enc-matrix returns the HTML table of all encodings and parts.
(defunconst wui-enc-matrix (matrix)
    `(table
      ,@(map
         (lambda (row) `(tr (th ,(car row)) ,@(map wui-tdata-link (cdr row))))
         matrix)))

;; CSS-ROLE-map is a mapping (pair list, assoc list) of role names to zettel
;; identifier. It is used in the base template to update the metadata of the
;; HTML page to include some role specific CSS code.
;; Referenced in function "ROLE-DEFAULT-meta".
(defvar CSS-ROLE-map '())

;; ROLE-DEFAULT-meta returns some metadata for the base template. Any role
;; specific code should include the returned list of this function.
(defunconst ROLE-DEFAULT-meta (env)
    `(,@(let* ((meta-role (environment-lookup 'meta-role env))
               (entry (assoc CSS-ROLE-map meta-role)))
              (if (pair? entry)
                  `((link (@ (rel "stylesheet") (href ,(zid-content-path (cdr entry))))))
              )
        )
    )
)

;;; ACTION-SEPARATOR defines a HTML value that separates actions links.
(defvar ACTION-SEPARATOR '(@H " · "))

;;; ROLE-DEFAULT-actions returns the default text for actions.
(defunconst ROLE-DEFAULT-actions (env)
    `(,@(let ((copy-url (environment-lookup 'copy-url env)))
             (if (defined? copy-url) `((@H " · ") (a (@ (href ,copy-url)) "Copy"))))
      ,@(let ((version-url (environment-lookup 'version-url env)))
             (if (defined? version-url) `((@H " · ") (a (@ (href ,version-url)) "Version"))))
      ,@(let ((child-url (environment-lookup 'child-url env)))
             (if (defined? child-url) `((@H " · ") (a (@ (href ,child-url)) "Child"))))
      ,@(let ((folge-url (environment-lookup 'folge-url env)))
             (if (defined? folge-url) `((@H " · ") (a (@ (href ,folge-url)) "Folge"))))
    )
)

;;; ROLE-tag-actions returns an additional action "Zettel" for zettel with role "tag".
(defunconst ROLE-tag-actions (env)
    `(,@(ROLE-DEFAULT-actions env)
      ,@(let ((title (environment-lookup 'title env)))
             (if (and (defined? title) title)
                 `(,ACTION-SEPARATOR (a (@ (href ,(query->url (string-append "tags:" title)))) "Zettel"))
             )
        )
    )
)

;;; ROLE-DEFAULT-heading returns the default text for headings, below the
;;; references of a zettel. In most cases it should be called from an
;;; overwriting function.
(defunconst ROLE-DEFAULT-heading (env)
    `(,@(let ((meta-url (environment-lookup 'meta-url env)))
           (if (defined? meta-url) `((br) "URL: " ,(url-to-html meta-url))))
      ,@(let ((meta-author (environment-lookup 'meta-author env)))
           (if (and (defined? meta-author) meta-author) `((br) "By " ,meta-author)))
    )
)

`(article
  (header
    (h1 ,heading)
    (div (@ (class "zs-meta"))
      ,@(if (bound? 'edit-url) `((a (@ (href ,edit-url)) "Edit") (@H " · ")))
      ,zid (@H " · ")
      (a (@ (href ,info-url)) "Info") (@H " · ")
      "(" ,@(if (bound? 'role-url) `((a (@ (href ,role-url)) ,meta-role)))
          ,@(if (and (bound? 'folge-role-url) (bound? 'meta-folge-role))
                `((@H " → ") (a (@ (href ,folge-role-url)) ,meta-folge-role)))
      ")"
      ,@(if tag-refs `((@H " · ") ,@tag-refs))
      ,@(ROLE-DEFAULT-actions (current-environment))



      ,@(if predecessor-refs `((br) "Predecessor: " ,predecessor-refs))
      ,@(if precursor-refs `((br) "Precursor: " ,precursor-refs))
      ,@(if superior-refs `((br) "Superior: " ,superior-refs))
      ,@(ROLE-DEFAULT-heading (current-environment))

    )
  )
  ,@content
  ,endnotes
  ,@(if (or folge-links subordinate-links back-links successor-links)
    `((nav
      ,@(if folge-links `((details (@ (,folge-open)) (summary "Folgezettel") (ul ,@(map wui-item-link folge-links)))))
      ,@(if subordinate-links `((details (@ (,subordinate-open)) (summary "Subordinates") (ul ,@(map wui-item-link subordinate-links)))))
      ,@(if back-links `((details (@ (,back-open)) (summary "Incoming") (ul ,@(map wui-item-link back-links)))))
      ,@(if successor-links `((details (@ (,successor-open)) (summary "Successors") (ul ,@(map wui-item-link successor-links)))))
     ))
  )
)

	dp.log.Trace().Err(err).Zid(meta.Zid).Msg("CreateZettel")
	return meta.Zid, err
}

func (dp *dirBox) GetZettel(ctx context.Context, zid id.Zid) (zettel.Zettel, error) {
	entry := dp.dirSrv.GetDirEntry(zid)
	if !entry.IsValid() {
		return zettel.Zettel{}, box.ErrZettelNotFound{Zid: zid}
	}
	m, c, err := dp.srvGetMetaContent(ctx, entry, zid)
	if err != nil {
		return zettel.Zettel{}, err
	}
	zettel := zettel.Zettel{Meta: m, Content: zettel.NewContent(c)}
	dp.log.Trace().Zid(zid).Msg("GetZettel")

	if dp.readonly {
		return box.ErrReadOnly
	}

	meta := zettel.Meta
	zid := meta.Zid
	if !zid.IsValid() {
		return box.ErrInvalidZid{Zid: zid.String()}
	}
	entry := dp.dirSrv.GetDirEntry(zid)
	if !entry.IsValid() {
		// Existing zettel, but new in this box.
		entry = &notify.DirEntry{Zid: zid}
	}
	dp.updateEntryFromMetaContent(entry, meta, zettel.Content)

func (dp *dirBox) RenameZettel(ctx context.Context, curZid, newZid id.Zid) error {
	if curZid == newZid {
		return nil
	}
	curEntry := dp.dirSrv.GetDirEntry(curZid)
	if !curEntry.IsValid() {
		return box.ErrZettelNotFound{Zid: curZid}
	}
	if dp.readonly {
		return box.ErrReadOnly
	}

	// Check whether zettel with new ID already exists in this box.
	if dp.HasZettel(ctx, newZid) {
		return box.ErrInvalidZid{Zid: newZid.String()}
	}

	oldMeta, oldContent, err := dp.srvGetMetaContent(ctx, curEntry, curZid)
	if err != nil {
		return err
	}

func (dp *dirBox) DeleteZettel(ctx context.Context, zid id.Zid) error {
	if dp.readonly {
		return box.ErrReadOnly
	}

	entry := dp.dirSrv.GetDirEntry(zid)
	if !entry.IsValid() {
		return box.ErrZettelNotFound{Zid: zid}
	}
	err := dp.dirSrv.DeleteDirEntry(zid)
	if err != nil {
		return nil
	}
	err = dp.srvDeleteZettel(ctx, entry, zid)
	if err == nil {

	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func fileService(i uint32, log *logger.Logger, dirPath string, cmds <-chan fileCmd) {
	// Something may panic. Ensure a running service.
	defer func() {
		if ri := recover(); ri != nil {
			kernel.Main.LogRecover("FileService", ri)
			go fileService(i, log, dirPath, cmds)
		}
	}()

	log.Trace().Uint("i", uint64(i)).Str("dirpath", dirPath).Msg("File service started")
	for cmd := range cmds {
		cmd.run(log, dirPath)

}

func (zb *zipBox) Stop(context.Context) {
	zb.dirSrv.Stop()
	zb.dirSrv = nil
}









func (zb *zipBox) GetZettel(_ context.Context, zid id.Zid) (zettel.Zettel, error) {
	entry := zb.dirSrv.GetDirEntry(zid)
	if !entry.IsValid() {
		return zettel.Zettel{}, box.ErrZettelNotFound{Zid: zid}
	}
	reader, err := zip.OpenReader(zb.name)
	if err != nil {
		return zettel.Zettel{}, err
	}
	defer reader.Close()

		}
		zb.enricher.Enrich(ctx, m, zb.number)
		handle(m)
	}
	return nil
}









func (zb *zipBox) AllowRenameZettel(_ context.Context, zid id.Zid) bool {
	entry := zb.dirSrv.GetDirEntry(zid)
	return !entry.IsValid()
}

func (zb *zipBox) RenameZettel(_ context.Context, curZid, newZid id.Zid) error {
	err := box.ErrReadOnly
	if curZid == newZid {
		err = nil
	}
	curEntry := zb.dirSrv.GetDirEntry(curZid)
	if !curEntry.IsValid() {
		err = box.ErrZettelNotFound{Zid: curZid}
	}
	zb.log.Trace().Err(err).Msg("RenameZettel")
	return err
}

func (*zipBox) CanDeleteZettel(context.Context, id.Zid) bool { return false }

func (zb *zipBox) DeleteZettel(_ context.Context, zid id.Zid) error {
	err := box.ErrReadOnly
	entry := zb.dirSrv.GetDirEntry(zid)
	if !entry.IsValid() {
		err = box.ErrZettelNotFound{Zid: zid}
	}
	zb.log.Trace().Err(err).Msg("DeleteZettel")
	return err
}

func (zb *zipBox) ReadStats(st *box.ManagedBoxStats) {
	st.ReadOnly = true

const (
	arNothing arAction = iota
	arReload
	arZettel
)

type anteroom struct {

	next    *anteroom
	waiting id.Set
	curLoad int
	reload  bool
}

type anteroomQueue struct {
	mx      sync.Mutex

	first   *anteroom
	last    *anteroom
	maxLoad int
}

func newAnteroomQueue(maxLoad int) *anteroomQueue { return &anteroomQueue{maxLoad: maxLoad} }

func (ar *anteroomQueue) EnqueueZettel(zid id.Zid) {
	if !zid.IsValid() {
		return
	}
	ar.mx.Lock()
	defer ar.mx.Unlock()
	if ar.first == nil {
		ar.first = ar.makeAnteroom(zid)
		ar.last = ar.first
		return
	}
	for room := ar.first; room != nil; room = room.next {
		if room.reload {
			continue // Do not put zettel in reload room
		}
		if _, ok := room.waiting[zid]; ok {
			// Zettel is already waiting. Nothing to do.
			return
		}
	}
	if room := ar.last; !room.reload && (ar.maxLoad == 0 || room.curLoad < ar.maxLoad) {
		room.waiting.Add(zid)
		room.curLoad++
		return
	}
	room := ar.makeAnteroom(zid)
	ar.last.next = room
	ar.last = room
}

func (ar *anteroomQueue) makeAnteroom(zid id.Zid) *anteroom {

	if zid == id.Invalid {




		panic(zid)
	}
	waiting := id.NewSetCap(max(ar.maxLoad, 100), zid)
	return &anteroom{next: nil, waiting: waiting, curLoad: 1, reload: false}
}

func (ar *anteroomQueue) Reset() {
	ar.mx.Lock()
	defer ar.mx.Unlock()
	ar.first = &anteroom{next: nil, waiting: nil, curLoad: 0, reload: true}
	ar.last = ar.first
}

func (ar *anteroomQueue) Reload(allZids id.Set) {
	ar.mx.Lock()
	defer ar.mx.Unlock()
	ar.deleteReloadedRooms()

	if ns := len(allZids); ns > 0 {

		ar.first = &anteroom{next: ar.first, waiting: allZids, curLoad: ns, reload: true}
		if ar.first.next == nil {
			ar.last = ar.first
		}


	} else {
		ar.first = nil
		ar.last = nil

	}
}

func (ar *anteroomQueue) deleteReloadedRooms() {
	room := ar.first
	for room != nil && room.reload {
		room = room.next
	}
	ar.first = room
	if room == nil {
		ar.last = nil
	}
}

func (ar *anteroomQueue) Dequeue() (arAction, id.Zid, bool) {
	ar.mx.Lock()
	defer ar.mx.Unlock()
	first := ar.first


	if first != nil {
		if first.waiting == nil && first.reload {
			ar.removeFirst()
			return arReload, id.Invalid, false
		}
		for zid := range first.waiting {
			delete(first.waiting, zid)
			if len(first.waiting) == 0 {
				ar.removeFirst()
			}
			return arZettel, zid, first.reload
		}
		ar.removeFirst()
	}
	return arNothing, id.Invalid, false
}

func (ar *anteroomQueue) removeFirst() {
	ar.first = ar.first.next
	if ar.first == nil {
		ar.last = nil
	}
}

	"testing"

	"zettelstore.de/z/zettel/id"
)

func TestSimple(t *testing.T) {
	t.Parallel()
	ar := newAnteroomQueue(2)
	ar.EnqueueZettel(id.Zid(1))
	action, zid, lastReload := ar.Dequeue()
	if zid != id.Zid(1) || action != arZettel || lastReload {
		t.Errorf("Expected arZettel/1/false, but got %v/%v/%v", action, zid, lastReload)
	}
	_, zid, _ = ar.Dequeue()
	if zid != id.Invalid {
		t.Errorf("Expected invalid Zid, but got %v", zid)
	}
	ar.EnqueueZettel(id.Zid(1))
	ar.EnqueueZettel(id.Zid(2))

	if count != 3 {
		t.Errorf("Expected 3 dequeues, but got %v", count)
	}
}

func TestReset(t *testing.T) {
	t.Parallel()
	ar := newAnteroomQueue(1)
	ar.EnqueueZettel(id.Zid(1))
	ar.Reset()
	action, zid, _ := ar.Dequeue()
	if action != arReload || zid != id.Invalid {
		t.Errorf("Expected reload & invalid Zid, but got %v/%v", action, zid)
	}
	ar.Reload(id.NewSet(3, 4))

		t.Errorf("Expected 5/arZettel, but got %v/%v", zid, action)
	}
	action, zid, _ = ar.Dequeue()
	if action != arNothing || zid != id.Invalid {
		t.Errorf("Expected nothing & invalid Zid, but got %v/%v", action, zid)
	}

	ar = newAnteroomQueue(1)
	ar.Reload(id.NewSet(id.Zid(6)))
	action, zid, _ = ar.Dequeue()
	if zid != id.Zid(6) || action != arZettel {
		t.Errorf("Expected 6/arZettel, but got %v/%v", zid, action)
	}
	action, zid, _ = ar.Dequeue()
	if action != arNothing || zid != id.Invalid {
		t.Errorf("Expected nothing & invalid Zid, but got %v/%v", action, zid)
	}

	ar = newAnteroomQueue(1)
	ar.EnqueueZettel(id.Zid(8))
	ar.Reload(nil)
	action, zid, _ = ar.Dequeue()
	if action != arNothing || zid != id.Invalid {
		t.Errorf("Expected nothing & invalid Zid, but got %v/%v", action, zid)
	}
}

		sb.WriteString(mgr.boxes[i].Location())
	}
	return sb.String()
}

// CanCreateZettel returns true, if box could possibly create a new zettel.
func (mgr *Manager) CanCreateZettel(ctx context.Context) bool {
	if mgr.State() != box.StartStateStarted {
		return false
	}
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	if box, isWriteBox := mgr.boxes[0].(box.WriteBox); isWriteBox {
		return box.CanCreateZettel(ctx)
	}
	return false
}

// CreateZettel creates a new zettel.
func (mgr *Manager) CreateZettel(ctx context.Context, zettel zettel.Zettel) (id.Zid, error) {
	mgr.mgrLog.Debug().Msg("CreateZettel")
	if mgr.State() != box.StartStateStarted {
		return id.Invalid, box.ErrStopped
	}
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	if box, isWriteBox := mgr.boxes[0].(box.WriteBox); isWriteBox {
		zettel.Meta = mgr.cleanMetaProperties(zettel.Meta)
		zid, err := box.CreateZettel(ctx, zettel)
		if err == nil {
			mgr.idxUpdateZettel(ctx, zettel)
		}
		return zid, err
	}
	return id.Invalid, box.ErrReadOnly
}

// GetZettel retrieves a specific zettel.
func (mgr *Manager) GetZettel(ctx context.Context, zid id.Zid) (zettel.Zettel, error) {
	mgr.mgrLog.Debug().Zid(zid).Msg("GetZettel")
	if mgr.State() != box.StartStateStarted {
		return zettel.Zettel{}, box.ErrStopped
	}
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	for i, p := range mgr.boxes {
		var errZNF box.ErrZettelNotFound
		if z, err := p.GetZettel(ctx, zid); !errors.As(err, &errZNF) {
			if err == nil {
				mgr.Enrich(ctx, z.Meta, i+1)
			}
			return z, err
		}
	}
	return zettel.Zettel{}, box.ErrZettelNotFound{Zid: zid}
}

// GetAllZettel retrieves a specific zettel from all managed boxes.
func (mgr *Manager) GetAllZettel(ctx context.Context, zid id.Zid) ([]zettel.Zettel, error) {
	mgr.mgrLog.Debug().Zid(zid).Msg("GetAllZettel")
	if mgr.State() != box.StartStateStarted {
		return nil, box.ErrStopped

	if mgr.State() != box.StartStateStarted {
		return nil, box.ErrStopped
	}
	result := id.Set{}
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	for _, p := range mgr.boxes {
		err := p.ApplyZid(ctx, func(zid id.Zid) { result.Add(zid) }, func(id.Zid) bool { return true })
		if err != nil {
			return nil, err
		}
	}
	return result, nil
}

		return result, nil
	}
	selected := map[id.Zid]*meta.Meta{}
	for _, term := range compSearch.Terms {
		rejected := id.Set{}
		handleMeta := func(m *meta.Meta) {
			zid := m.Zid
			if rejected.ContainsOrNil(zid) {
				mgr.mgrLog.Trace().Zid(zid).Msg("SelectMeta/alreadyRejected")
				return
			}
			if _, ok := selected[zid]; ok {
				mgr.mgrLog.Trace().Zid(zid).Msg("SelectMeta/alreadySelected")
				return
			}
			if compSearch.PreMatch(m) && term.Match(m) {
				selected[zid] = m
				mgr.mgrLog.Trace().Zid(zid).Msg("SelectMeta/match")
			} else {
				rejected.Add(zid)
				mgr.mgrLog.Trace().Zid(zid).Msg("SelectMeta/reject")
			}
		}
		for _, p := range mgr.boxes {
			if err2 := p.ApplyMeta(ctx, handleMeta, term.Retrieve); err2 != nil {
				return nil, err2
			}
		}
	}
	result := make([]*meta.Meta, 0, len(selected))
	for _, m := range selected {
		result = append(result, m)
	}
	result = compSearch.AfterSearch(result)
	mgr.mgrLog.Trace().Int("count", int64(len(result))).Msg("found with ApplyMeta")
	return result, nil
}

// CanUpdateZettel returns true, if box could possibly update the given zettel.
func (mgr *Manager) CanUpdateZettel(ctx context.Context, zettel zettel.Zettel) bool {
	if mgr.State() != box.StartStateStarted {
		return false
	}
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	if box, isWriteBox := mgr.boxes[0].(box.WriteBox); isWriteBox {
		return box.CanUpdateZettel(ctx, zettel)
	}
	return false

}

// UpdateZettel updates an existing zettel.
func (mgr *Manager) UpdateZettel(ctx context.Context, zettel zettel.Zettel) error {
	mgr.mgrLog.Debug().Zid(zettel.Meta.Zid).Msg("UpdateZettel")
	if mgr.State() != box.StartStateStarted {
		return box.ErrStopped
	}
	if box, isWriteBox := mgr.boxes[0].(box.WriteBox); isWriteBox {
		zettel.Meta = mgr.cleanMetaProperties(zettel.Meta)
		if err := box.UpdateZettel(ctx, zettel); err != nil {

			return err
		}
		mgr.idxUpdateZettel(ctx, zettel)
		return nil
	}
	return box.ErrReadOnly
}

// AllowRenameZettel returns true, if box will not disallow renaming the zettel.
func (mgr *Manager) AllowRenameZettel(ctx context.Context, zid id.Zid) bool {
	if mgr.State() != box.StartStateStarted {
		return false
	}

	if mgr.State() != box.StartStateStarted {
		return box.ErrStopped
	}
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	for i, p := range mgr.boxes {
		err := p.RenameZettel(ctx, curZid, newZid)
		var errZNF box.ErrZettelNotFound
		if err != nil && !errors.As(err, &errZNF) {
			for j := 0; j < i; j++ {
				mgr.boxes[j].RenameZettel(ctx, newZid, curZid)
			}
			return err
		}
	}
	mgr.idxRenameZettel(ctx, curZid, newZid)
	return nil
}

// CanDeleteZettel returns true, if box could possibly delete the given zettel.
func (mgr *Manager) CanDeleteZettel(ctx context.Context, zid id.Zid) bool {
	if mgr.State() != box.StartStateStarted {
		return false

		return box.ErrStopped
	}
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	for _, p := range mgr.boxes {
		err := p.DeleteZettel(ctx, zid)
		if err == nil {
			mgr.idxDeleteZettel(ctx, zid)
			return nil
		}
		var errZNF box.ErrZettelNotFound
		if !errors.As(err, &errZNF) && !errors.Is(err, box.ErrReadOnly) {
			return err
		}
	}
	return box.ErrZettelNotFound{Zid: zid}
}

// Remove all (computed) properties from metadata before storing the zettel.
func (mgr *Manager) cleanMetaProperties(m *meta.Meta) *meta.Meta {
	result := m.Clone()
	for _, p := range result.ComputedPairsRest() {
		if mgr.propertyKeys.Has(p.Key) {
			result.Delete(p.Key)
		}
	}
	return result
}

	if ref.IsExternal() {
		data.urls.Add(strings.ToLower(ref.Value))
	}
	if !ref.IsZettel() {
		return
	}
	if zid, err := id.Parse(ref.URL.Path); err == nil {
		data.refs.Add(zid)
	}
}

}

// idxIndexer runs in the background and updates the index data structures.
// This is the main service of the idxIndexer.
func (mgr *Manager) idxIndexer() {
	// Something may panic. Ensure a running indexer.
	defer func() {
		if ri := recover(); ri != nil {
			kernel.Main.LogRecover("Indexer", ri)
			go mgr.idxIndexer()
		}
	}()

	timerDuration := 15 * time.Second
	timer := time.NewTimer(timerDuration)
	ctx := box.NoEnrichContext(context.Background())
	for {
		mgr.idxWorkService(ctx)
		if !mgr.idxSleepService(timer, timerDuration) {
			return
		}
	}
}

func (mgr *Manager) idxWorkService(ctx context.Context) {

	var start time.Time
	for {
		switch action, zid, lastReload := mgr.idxAr.Dequeue(); action {
		case arNothing:
			return
		case arReload:
			mgr.idxLog.Debug().Msg("reload")

			zids, err := mgr.FetchZids(ctx)
			if err == nil {
				start = time.Now()
				mgr.idxAr.Reload(zids)


				mgr.idxMx.Lock()
				mgr.idxLastReload = time.Now().Local()
				mgr.idxSinceReload = 0
				mgr.idxMx.Unlock()
			}
		case arZettel:
			mgr.idxLog.Debug().Zid(zid).Msg("zettel")
			zettel, err := mgr.GetZettel(ctx, zid)
			if err != nil {
				// Zettel was deleted or is not accessible b/c of other reasons
				mgr.idxLog.Trace().Zid(zid).Msg("delete")



				mgr.idxDeleteZettel(ctx, zid)
				continue
			}
			mgr.idxLog.Trace().Zid(zid).Msg("update")
			mgr.idxUpdateZettel(ctx, zettel)
			mgr.idxMx.Lock()
			if lastReload {
				mgr.idxDurReload = time.Since(start)
			}
			mgr.idxSinceReload++
			mgr.idxMx.Unlock()

		}
	}
}

func (mgr *Manager) idxSleepService(timer *time.Timer, timerDuration time.Duration) bool {
	select {
	case _, ok := <-mgr.idxReady:

			is := parser.ParseMetadata(pair.Value)
			collectInlineIndexData(&is, cData)
		case meta.TypeURL:
			if _, err := url.Parse(pair.Value); err == nil {
				cData.urls.Add(pair.Value)
			}
		default:
			if descr.Type.IsSet {
				for _, val := range meta.ListFromValue(pair.Value) {
					idxCollectMetaValue(cData.words, val)
				}
			} else {
				idxCollectMetaValue(cData.words, pair.Value)
			}
		}
	}
}

func idxCollectMetaValue(stWords store.WordSet, value string) {
	if words := strfun.NormalizeWords(value); len(words) > 0 {
		for _, word := range words {
			stWords.Add(word)
		}
	} else {
		stWords.Add(value)
	}
}

func (mgr *Manager) idxProcessData(ctx context.Context, zi *store.ZettelIndex, cData *collectData) {
	for ref := range cData.refs {
		if mgr.HasZettel(ctx, ref) {
			zi.AddBackRef(ref)
		} else {
			zi.AddDeadRef(ref)

	if inverseKey == "" {
		zi.AddBackRef(zid)
		return
	}
	zi.AddInverseRef(inverseKey, zid)
}

func (mgr *Manager) idxRenameZettel(ctx context.Context, curZid, newZid id.Zid) {
	toCheck := mgr.idxStore.RenameZettel(ctx, curZid, newZid)
	mgr.idxCheckZettel(toCheck)
}

func (mgr *Manager) idxDeleteZettel(ctx context.Context, zid id.Zid) {
	toCheck := mgr.idxStore.DeleteZettel(ctx, zid)
	mgr.idxCheckZettel(toCheck)
}

func (mgr *Manager) idxCheckZettel(s id.Set) {
	for zid := range s {
		mgr.idxAr.EnqueueZettel(zid)
	}
}

	done         chan struct{}
	infos        chan box.UpdateInfo
	propertyKeys strfun.Set // Set of property key names

	// Indexer data
	idxLog   *logger.Logger
	idxStore store.Store
	idxAr    *anteroomQueue
	idxReady chan struct{} // Signal a non-empty anteroom to background task

	// Indexer stats data
	idxMx          sync.RWMutex
	idxLastReload  time.Time
	idxDurReload   time.Duration
	idxSinceReload uint64

		mgrLog:       boxLog.Clone().Str("box", "manager").Child(),
		rtConfig:     rtConfig,
		infos:        make(chan box.UpdateInfo, len(boxURIs)*10),
		propertyKeys: propertyKeys,

		idxLog:   boxLog.Clone().Str("box", "index").Child(),
		idxStore: memstore.New(),
		idxAr:    newAnteroomQueue(1000),
		idxReady: make(chan struct{}, 1),
	}
	cdata := ConnectData{Number: 1, Config: rtConfig, Enricher: mgr, Notify: mgr.infos}
	boxes := make([]box.ManagedBox, 0, len(boxURIs)+2)
	for _, uri := range boxURIs {
		p, err := Connect(uri, authManager, &cdata)
		if err != nil {

		mgr.mxObserver.Unlock()
	}
}

func (mgr *Manager) notifier() {
	// The call to notify may panic. Ensure a running notifier.
	defer func() {
		if ri := recover(); ri != nil {
			kernel.Main.LogRecover("Notifier", ri)
			go mgr.notifier()
		}
	}()

	tsLastEvent := time.Now()
	cache := destutterCache{}
	for {

// Refresh internal box data.
func (mgr *Manager) Refresh(ctx context.Context) error {
	mgr.mgrLog.Debug().Msg("Refresh")
	if mgr.State() != box.StartStateStarted {
		return box.ErrStopped
	}
	mgr.infos <- box.UpdateInfo{Reason: box.OnReload, Zid: id.Invalid}
	mgr.mgrMx.Lock()
	defer mgr.mgrMx.Unlock()

	for _, bx := range mgr.boxes {
		if rb, ok := bx.(box.Refresher); ok {
			rb.Refresh(ctx)
		}
	}
	return nil
}

// ReIndex data of the given zettel.
func (mgr *Manager) ReIndex(_ context.Context, zid id.Zid) error {
	mgr.mgrLog.Debug().Msg("ReIndex")
	if mgr.State() != box.StartStateStarted {
		return box.ErrStopped
	}
	mgr.infos <- box.UpdateInfo{Reason: box.OnReload, Zid: zid}
	return nil
}

// ReadStats populates st with box statistics.
func (mgr *Manager) ReadStats(st *box.Stats) {
	mgr.mgrLog.Debug().Msg("ReadStats")
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	subStats := make([]box.ManagedBoxStats, len(mgr.boxes))

type bidiRefs struct {
	forward  id.Slice
	backward id.Slice
}

type zettelData struct {
	meta      *meta.Meta // a local copy of the metadata, without computed keys
	dead      id.Slice   // list of dead references in this zettel
	forward   id.Slice   // list of forward references in this zettel
	backward  id.Slice   // list of zettel that reference with zettel
	otherRefs map[string]bidiRefs
	words     []string // list of words of this zettel
	urls      []string // list of urls of this zettel
}

type stringRefs map[string]id.Slice

type memStore struct {
	mx     sync.RWMutex
	intern map[string]string // map to intern strings

		urls:   make(stringRefs),
	}
}

func (ms *memStore) GetMeta(_ context.Context, zid id.Zid) (*meta.Meta, error) {
	ms.mx.RLock()
	defer ms.mx.RUnlock()
	if zi, found := ms.idx[zid]; found && zi.meta != nil {
		// zi.meta is nil, if zettel was referenced, but is not indexed yet.
		return zi.meta.Clone(), nil
	}
	return nil, box.ErrZettelNotFound{Zid: zid}
}

func (ms *memStore) Enrich(_ context.Context, m *meta.Meta) {
	if ms.doEnrich(m) {
		ms.mxStats.Lock()
		ms.updates++
		ms.mxStats.Unlock()

		return false
	}
	var updated bool
	if len(zi.dead) > 0 {
		m.Set(api.KeyDead, zi.dead.String())
		updated = true
	}
	back := removeOtherMetaRefs(m, zi.backward.Clone())
	if len(zi.backward) > 0 {
		m.Set(api.KeyBackward, zi.backward.String())
		updated = true
	}
	if len(zi.forward) > 0 {
		m.Set(api.KeyForward, zi.forward.String())
		back = remRefs(back, zi.forward)

// SearchEqual returns all zettel that contains the given exact word.
// The word must be normalized through Unicode NKFD, trimmed and not empty.
func (ms *memStore) SearchEqual(word string) id.Set {
	ms.mx.RLock()
	defer ms.mx.RUnlock()
	result := id.NewSet()
	if refs, ok := ms.words[word]; ok {
		result.CopySlice(refs)
	}
	if refs, ok := ms.urls[word]; ok {
		result.CopySlice(refs)
	}
	zid, err := id.Parse(word)
	if err != nil {
		return result
	}
	zi, ok := ms.idx[zid]
	if !ok {

func (ms *memStore) selectWithPred(s string, pred func(string, string) bool) id.Set {
	// Must only be called if ms.mx is read-locked!
	result := id.NewSet()
	for word, refs := range ms.words {
		if !pred(word, s) {
			continue
		}
		result.CopySlice(refs)
	}
	for u, refs := range ms.urls {
		if !pred(u, s) {
			continue
		}
		result.CopySlice(refs)
	}
	return result
}

func addBackwardZids(result id.Set, zid id.Zid, zi *zettelData) {
	// Must only be called if ms.mx is read-locked!
	result.Add(zid)
	result.CopySlice(zi.backward)
	for _, mref := range zi.otherRefs {
		result.CopySlice(mref.backward)
	}
}

func removeOtherMetaRefs(m *meta.Meta, back id.Slice) id.Slice {
	for _, p := range m.PairsRest() {
		switch meta.Type(p.Key) {
		case meta.TypeID:

			}
		}
	}
	return back
}

func (ms *memStore) UpdateReferences(_ context.Context, zidx *store.ZettelIndex) id.Set {

	ms.mx.Lock()
	defer ms.mx.Unlock()
	m := ms.makeMeta(zidx)
	zi, ziExist := ms.idx[zidx.Zid]
	if !ziExist || zi == nil {
		zi = &zettelData{}
		ziExist = false
	}

	// Is this zettel an old dead reference mentioned in other zettel?
	var toCheck id.Set
	if refs, ok := ms.dead[zidx.Zid]; ok {
		// These must be checked later again
		toCheck = id.NewSet(refs...)
		delete(ms.dead, zidx.Zid)
	}

	zi.meta = m
	ms.updateDeadReferences(zidx, zi)
	ids := ms.updateForwardBackwardReferences(zidx, zi)
	toCheck = toCheck.Copy(ids)
	ids = ms.updateMetadataReferences(zidx, zi)
	toCheck = toCheck.Copy(ids)
	zi.words = updateStrings(zidx.Zid, ms.words, zi.words, zidx.GetWords())
	zi.urls = updateStrings(zidx.Zid, ms.urls, zi.urls, zidx.GetUrls())

	// Check if zi must be inserted into ms.idx
	if !ziExist {
		ms.idx[zidx.Zid] = zi
	}

	return toCheck

		ms.dead[ref] = remRef(ms.dead[ref], zidx.Zid)
	}
	for _, ref := range newRefs {
		ms.dead[ref] = addRef(ms.dead[ref], zidx.Zid)
	}
}

func (ms *memStore) updateForwardBackwardReferences(zidx *store.ZettelIndex, zi *zettelData) id.Set {
	// Must only be called if ms.mx is write-locked!
	brefs := zidx.GetBackRefs()
	newRefs, remRefs := refsDiff(brefs, zi.forward)
	zi.forward = brefs

	var toCheck id.Set
	for _, ref := range remRefs {
		bzi := ms.getOrCreateEntry(ref)
		bzi.backward = remRef(bzi.backward, zidx.Zid)
		if bzi.meta == nil {
			toCheck = toCheck.Add(ref)
		}
	}
	for _, ref := range newRefs {
		bzi := ms.getOrCreateEntry(ref)
		bzi.backward = addRef(bzi.backward, zidx.Zid)
		if bzi.meta == nil {
			toCheck = toCheck.Add(ref)
		}
	}
	return toCheck
}

func (ms *memStore) updateMetadataReferences(zidx *store.ZettelIndex, zi *zettelData) id.Set {
	// Must only be called if ms.mx is write-locked!
	inverseRefs := zidx.GetInverseRefs()
	for key, mr := range zi.otherRefs {
		if _, ok := inverseRefs[key]; ok {
			continue
		}
		ms.removeInverseMeta(zidx.Zid, key, mr.forward)
	}
	if zi.otherRefs == nil {
		zi.otherRefs = make(map[string]bidiRefs)
	}
	var toCheck id.Set
	for key, mrefs := range inverseRefs {
		mr := zi.otherRefs[key]
		newRefs, remRefs := refsDiff(mrefs, mr.forward)
		mr.forward = mrefs
		zi.otherRefs[key] = mr

		for _, ref := range newRefs {
			bzi := ms.getOrCreateEntry(ref)
			if bzi.otherRefs == nil {
				bzi.otherRefs = make(map[string]bidiRefs)
			}
			bmr := bzi.otherRefs[key]
			bmr.backward = addRef(bmr.backward, zidx.Zid)
			bzi.otherRefs[key] = bmr
			if bzi.meta == nil {
				toCheck = toCheck.Add(ref)
			}
		}
		ms.removeInverseMeta(zidx.Zid, key, remRefs)
	}
	return toCheck
}

func updateStrings(zid id.Zid, srefs stringRefs, prev []string, next store.WordSet) []string {
	newWords, removeWords := next.Diff(prev)
	for _, word := range newWords {
		if refs, ok := srefs[word]; ok {
			srefs[word] = addRef(refs, zid)
			continue
		}
		srefs[word] = id.Slice{zid}

			continue
		}
		srefs[word] = refs2
	}
	return next.Words()
}

func (ms *memStore) getOrCreateEntry(zid id.Zid) *zettelData {
	// Must only be called if ms.mx is write-locked!
	if zi, ok := ms.idx[zid]; ok {
		return zi
	}
	zi := &zettelData{}
	ms.idx[zid] = zi
	return zi
}

func (ms *memStore) RenameZettel(_ context.Context, curZid, newZid id.Zid) id.Set {
	ms.mx.Lock()
	defer ms.mx.Unlock()

	curZi, curFound := ms.idx[curZid]
	_, newFound := ms.idx[newZid]
	if !curFound || newFound {
		return nil
	}
	newZi := &zettelData{
		meta:      copyMeta(curZi.meta, newZid),
		dead:      ms.copyDeadReferences(curZi.dead),
		forward:   ms.copyForward(curZi.forward, newZid),
		backward:  nil, // will be done through tocheck
		otherRefs: nil, // TODO: check if this will be done through toCheck
		words:     copyStrings(ms.words, curZi.words, newZid),
		urls:      copyStrings(ms.urls, curZi.urls, newZid),
	}

	ms.idx[newZid] = newZi
	toCheck := ms.doDeleteZettel(curZid)
	toCheck = toCheck.CopySlice(ms.dead[newZid])
	delete(ms.dead, newZid)
	toCheck = toCheck.Add(newZid) // should update otherRefs
	return toCheck
}
func copyMeta(m *meta.Meta, newZid id.Zid) *meta.Meta {
	result := m.Clone()
	result.Zid = newZid
	return result
}
func (ms *memStore) copyDeadReferences(curDead id.Slice) id.Slice {
	// Must only be called if ms.mx is write-locked!
	if l := len(curDead); l > 0 {
		result := make(id.Slice, l)
		for i, ref := range curDead {
			result[i] = ref
			ms.dead[ref] = addRef(ms.dead[ref], ref)
		}
		return result
	}
	return nil
}
func (ms *memStore) copyForward(curForward id.Slice, newZid id.Zid) id.Slice {
	// Must only be called if ms.mx is write-locked!
	if l := len(curForward); l > 0 {
		result := make(id.Slice, l)
		for i, ref := range curForward {
			result[i] = ref
			if fzi, found := ms.idx[ref]; found {
				fzi.backward = addRef(fzi.backward, newZid)
			}
		}
		return result
	}
	return nil
}
func copyStrings(msStringMap stringRefs, curStrings []string, newZid id.Zid) []string {
	// Must only be called if ms.mx is write-locked!
	if l := len(curStrings); l > 0 {
		result := make([]string, l)
		for i, s := range curStrings {
			result[i] = s
			msStringMap[s] = addRef(msStringMap[s], newZid)
		}
		return result
	}
	return nil
}

func (ms *memStore) DeleteZettel(_ context.Context, zid id.Zid) id.Set {
	ms.mx.Lock()
	defer ms.mx.Unlock()
	return ms.doDeleteZettel(zid)
}

func (ms *memStore) doDeleteZettel(zid id.Zid) id.Set {
	// Must only be called if ms.mx is write-locked!
	zi, ok := ms.idx[zid]
	if !ok {
		return nil
	}

	ms.deleteDeadSources(zid, zi)
	toCheck := ms.deleteForwardBackward(zid, zi)

	for key, mrefs := range zi.otherRefs {
		ms.removeInverseMeta(zid, key, mrefs.forward)
	}

	deleteStrings(ms.words, zi.words, zid)
	deleteStrings(ms.urls, zi.urls, zid)
	delete(ms.idx, zid)
	return toCheck
}

func (ms *memStore) deleteDeadSources(zid id.Zid, zi *zettelData) {
	// Must only be called if ms.mx is write-locked!
	for _, ref := range zi.dead {
		if drefs, ok := ms.dead[ref]; ok {
			drefs = remRef(drefs, zid)
			if len(drefs) > 0 {
				ms.dead[ref] = drefs
			} else {
				delete(ms.dead, ref)
			}
		}
	}
}

func (ms *memStore) deleteForwardBackward(zid id.Zid, zi *zettelData) id.Set {
	// Must only be called if ms.mx is write-locked!

	for _, ref := range zi.forward {
		if fzi, ok := ms.idx[ref]; ok {
			fzi.backward = remRef(fzi.backward, zid)
		}
	}
	var toCheck id.Set
	for _, ref := range zi.backward {
		if bzi, ok := ms.idx[ref]; ok {
			bzi.forward = remRef(bzi.forward, zid)

			toCheck = toCheck.Add(ref)


		}
	}
	return toCheck
}

func (ms *memStore) removeInverseMeta(zid id.Zid, key string, forward id.Slice) {
	// Must only be called if ms.mx is write-locked!

			if len(bzi.otherRefs) == 0 {
				bzi.otherRefs = nil
			}
		}
	}
}

func deleteStrings(msStringMap stringRefs, curStrings []string, zid id.Zid) {
	// Must only be called if ms.mx is write-locked!
	for _, word := range curStrings {
		refs, ok := msStringMap[word]
		if !ok {
			continue
		}
		refs2 := remRef(refs, zid)
		if len(refs2) == 0 {
			delete(msStringMap, word)
			continue
		}
		msStringMap[word] = refs2
	}
}

func (ms *memStore) ReadStats(st *store.Stats) {
	ms.mx.RLock()
	st.Zettel = len(ms.idx)
	st.Words = uint64(len(ms.words))

//-----------------------------------------------------------------------------
// Copyright (c) 2021-present Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package memstore

import (
	"slices"

	"zettelstore.de/z/zettel/id"
)

func refsDiff(refsN, refsO id.Slice) (newRefs, remRefs id.Slice) {
	npos, opos := 0, 0
	for npos < len(refsN) && opos < len(refsO) {
		rn, ro := refsN[npos], refsO[opos]
		if rn == ro {
			npos++

			return refs
		} else if r < ref {
			lo = m + 1
		} else {
			hi = m
		}
	}
	refs = slices.Insert(refs, hi, ref)


	return refs
}

func remRefs(refs, rem id.Slice) id.Slice {
	if len(refs) == 0 || len(rem) == 0 {
		return refs
	}

	// Entrich metadata with data from store.
	Enrich(ctx context.Context, m *meta.Meta)

	// UpdateReferences for a specific zettel.
	// Returns set of zettel identifier that must also be checked for changes.
	UpdateReferences(context.Context, *ZettelIndex) id.Set

	// RenameZettel changes all references of current zettel identifier to new
	// zettel identifier.
	RenameZettel(_ context.Context, curZid, newZid id.Zid) id.Set

	// DeleteZettel removes index data for given zettel.
	// Returns set of zettel identifier that must also be checked for changes.
	DeleteZettel(context.Context, id.Zid) id.Set

	// ReadStats populates st with store statistics.
	ReadStats(st *Stats)

	// Dump the content to a Writer.
	Dump(io.Writer)
}

		deadrefs:    id.NewSet(),
	}
}

// AddBackRef adds a reference to a zettel where the current zettel links to
// without any more information.
func (zi *ZettelIndex) AddBackRef(zid id.Zid) {
	zi.backrefs.Add(zid)
}

// AddInverseRef adds a named reference to a zettel. On that zettel, the given
// metadata key should point back to the current zettel.
func (zi *ZettelIndex) AddInverseRef(key string, zid id.Zid) {
	if zids, ok := zi.inverseRefs[key]; ok {
		zids.Add(zid)
		return
	}
	zi.inverseRefs[key] = id.NewSet(zid)
}

// AddDeadRef adds a dead reference to a zettel.
func (zi *ZettelIndex) AddDeadRef(zid id.Zid) {
	zi.deadrefs.Add(zid)
}

// SetWords sets the words to the given value.
func (zi *ZettelIndex) SetWords(words WordSet) { zi.words = words }

// SetUrls sets the words to the given value.
func (zi *ZettelIndex) SetUrls(urls WordSet) { zi.urls = urls }

}

func (mb *memBox) GetZettel(_ context.Context, zid id.Zid) (zettel.Zettel, error) {
	mb.mx.RLock()
	z, ok := mb.zettel[zid]
	mb.mx.RUnlock()
	if !ok {
		return zettel.Zettel{}, box.ErrZettelNotFound{Zid: zid}
	}
	z.Meta = z.Meta.Clone()
	mb.log.Trace().Msg("GetZettel")
	return z, nil
}

func (mb *memBox) HasZettel(_ context.Context, zid id.Zid) bool {

	}
	return newBytes < mb.maxBytes
}

func (mb *memBox) UpdateZettel(_ context.Context, zettel zettel.Zettel) error {
	m := zettel.Meta.Clone()
	if !m.Zid.IsValid() {
		return box.ErrInvalidZid{Zid: m.Zid.String()}
	}

	mb.mx.Lock()
	newBytes := mb.curBytes + zettel.Length()
	if prevZettel, found := mb.zettel[m.Zid]; found {
		newBytes -= prevZettel.Length()
	}

func (*memBox) AllowRenameZettel(context.Context, id.Zid) bool { return true }

func (mb *memBox) RenameZettel(_ context.Context, curZid, newZid id.Zid) error {
	mb.mx.Lock()
	zettel, ok := mb.zettel[curZid]
	if !ok {
		mb.mx.Unlock()
		return box.ErrZettelNotFound{Zid: curZid}
	}

	// Check that there is no zettel with newZid
	if _, ok = mb.zettel[newZid]; ok {
		mb.mx.Unlock()
		return box.ErrInvalidZid{Zid: newZid.String()}
	}

	meta := zettel.Meta.Clone()
	meta.Zid = newZid
	zettel.Meta = meta
	mb.zettel[newZid] = zettel
	delete(mb.zettel, curZid)

}

func (mb *memBox) DeleteZettel(_ context.Context, zid id.Zid) error {
	mb.mx.Lock()
	oldZettel, found := mb.zettel[zid]
	if !found {
		mb.mx.Unlock()
		return box.ErrZettelNotFound{Zid: zid}
	}
	delete(mb.zettel, zid)
	mb.curBytes -= oldZettel.Length()
	mb.mx.Unlock()
	mb.notifyChanged(zid)
	mb.log.Trace().Msg("DeleteZettel")
	return nil

func (ds *DirService) RenameDirEntry(oldEntry *DirEntry, newZid id.Zid) (DirEntry, error) {
	ds.mx.Lock()
	defer ds.mx.Unlock()
	if ds.entries == nil {
		return DirEntry{}, ds.logMissingEntry("rename")
	}
	if _, found := ds.entries[newZid]; found {
		return DirEntry{}, box.ErrInvalidZid{Zid: newZid.String()}
	}
	oldZid := oldEntry.Zid
	newEntry := DirEntry{
		Zid:         newZid,
		MetaName:    renameFilename(oldEntry.MetaName, oldZid, newZid),
		ContentName: renameFilename(oldEntry.ContentName, oldZid, newZid),
		ContentExt:  oldEntry.ContentExt,

	delete(ds.entries, zid)
	return nil
}

func (ds *DirService) updateEvents(newEntries entrySet) {
	// Something may panic. Ensure a running service.
	defer func() {
		if ri := recover(); ri != nil {
			kernel.Main.LogRecover("DirectoryService", ri)
			go ds.updateEvents(newEntries)
		}
	}()

	for ev := range ds.notifier.Events() {
		e, ok := ds.handleEvent(ev, newEntries)
		if !ok {

		}
		return true
	}

	if ev.Has(fsnotify.Create) {
		err := fsdn.base.Add(fsdn.path)
		if err != nil {
			fsdn.log.Error().Err(err).Str("name", fsdn.path).Msg("Unable to add directory")
			select {
			case fsdn.events <- Event{Op: Error, Err: err}:
			case <-fsdn.done:
				fsdn.log.Trace().Int("i", 2).Msg("done dir event processing")
				return false
			}
		}

		zettel.Zettel{
			Meta:    m,
			Content: zettel.NewContent(inp.Src[inp.Pos:]),
		},
		m.GetDefault(api.KeySyntax, meta.SyntaxZmk),
		nil,
	)
	encdr := encoder.Create(api.Encoder(enc), &encoder.CreateParameter{Lang: m.GetDefault(api.KeyLang, api.ValueLangEN)})
	if encdr == nil {
		fmt.Fprintf(os.Stderr, "Unknown format %q\n", enc)
		return 2, nil
	}
	_, err = encdr.WriteZettel(os.Stdout, z, parser.ParseMetadata)
	if err != nil {
		return 2, err

	ucCreateZettel := usecase.NewCreateZettel(logUc, rtConfig, protectedBoxManager)
	ucGetAllZettel := usecase.NewGetAllZettel(protectedBoxManager)
	ucGetZettel := usecase.NewGetZettel(protectedBoxManager)
	ucParseZettel := usecase.NewParseZettel(rtConfig, ucGetZettel)
	ucQuery := usecase.NewQuery(protectedBoxManager)
	ucEvaluate := usecase.NewEvaluate(rtConfig, &ucGetZettel, &ucQuery)
	ucQuery.SetEvaluate(&ucEvaluate)
	ucTagZettel := usecase.NewTagZettel(protectedBoxManager, &ucQuery)
	ucRoleZettel := usecase.NewRoleZettel(protectedBoxManager, &ucQuery)
	ucListSyntax := usecase.NewListSyntax(protectedBoxManager)
	ucListRoles := usecase.NewListRoles(protectedBoxManager)
	ucDelete := usecase.NewDeleteZettel(logUc, protectedBoxManager)
	ucUpdate := usecase.NewUpdateZettel(logUc, protectedBoxManager)
	ucRename := usecase.NewRenameZettel(logUc, protectedBoxManager)
	ucRefresh := usecase.NewRefresh(logUc, protectedBoxManager)
	ucReIndex := usecase.NewReIndex(logUc, protectedBoxManager)
	ucVersion := usecase.NewVersion(kernel.Main.GetConfig(kernel.CoreService, kernel.CoreVersion).(string))

	a := api.New(
		webLog.Clone().Str("adapter", "api").Child(),
		webSrv, authManager, authManager, rtConfig, authPolicy)
	wui := webui.New(
		webLog.Clone().Str("adapter", "wui").Child(),

		webSrv.AddZettelRoute('c', server.MethodPost, wui.MakePostCreateZettelHandler(&ucCreateZettel))
		webSrv.AddZettelRoute('d', server.MethodGet, wui.MakeGetDeleteZettelHandler(ucGetZettel, ucGetAllZettel))
		webSrv.AddZettelRoute('d', server.MethodPost, wui.MakePostDeleteZettelHandler(&ucDelete))
		webSrv.AddZettelRoute('e', server.MethodGet, wui.MakeEditGetZettelHandler(ucGetZettel, ucListRoles, ucListSyntax))
		webSrv.AddZettelRoute('e', server.MethodPost, wui.MakeEditSetZettelHandler(&ucUpdate))
	}
	webSrv.AddListRoute('g', server.MethodGet, wui.MakeGetGoActionHandler(&ucRefresh))
	webSrv.AddListRoute('h', server.MethodGet, wui.MakeListHTMLMetaHandler(&ucQuery, &ucTagZettel, &ucRoleZettel, &ucReIndex))
	webSrv.AddZettelRoute('h', server.MethodGet, wui.MakeGetHTMLZettelHandler(&ucEvaluate, ucGetZettel))
	webSrv.AddListRoute('i', server.MethodGet, wui.MakeGetLoginOutHandler())
	webSrv.AddListRoute('i', server.MethodPost, wui.MakePostLoginHandler(&ucAuthenticate))
	webSrv.AddZettelRoute('i', server.MethodGet, wui.MakeGetInfoHandler(
		ucParseZettel, &ucEvaluate, ucGetZettel, ucGetAllZettel, &ucQuery))

	// API
	webSrv.AddListRoute('a', server.MethodPost, a.MakePostLoginHandler(&ucAuthenticate))
	webSrv.AddListRoute('a', server.MethodPut, a.MakeRenewAuthHandler())
	webSrv.AddListRoute('x', server.MethodGet, a.MakeGetDataHandler(ucVersion))
	webSrv.AddListRoute('x', server.MethodPost, a.MakePostCommandHandler(&ucIsAuth, &ucRefresh))
	webSrv.AddListRoute('z', server.MethodGet, a.MakeQueryHandler(&ucQuery, &ucTagZettel, &ucRoleZettel, &ucReIndex))
	webSrv.AddZettelRoute('z', server.MethodGet, a.MakeGetZettelHandler(ucGetZettel, ucParseZettel, ucEvaluate))
	if !authManager.IsReadonly() {
		webSrv.AddListRoute('z', server.MethodPost, a.MakePostCreateZettelHandler(&ucCreateZettel))
		webSrv.AddZettelRoute('z', server.MethodPut, a.MakeUpdateZettelHandler(&ucUpdate))
		webSrv.AddZettelRoute('z', server.MethodDelete, a.MakeDeleteZettelHandler(&ucDelete))
		webSrv.AddZettelRoute('z', server.MethodMove, a.MakeRenameZettelHandler(&ucRename))
	}

	"context"

	"zettelstore.de/z/zettel/meta"
)

// Key values that are supported by Config.Get
const (
	KeyFooterZettel         = "footer-zettel"
	KeyHomeZettel           = "home-zettel"
	KeyShowBackLinks        = "show-back-links"
	KeyShowFolgeLinks       = "show-folge-links"
	KeyShowSubordinateLinks = "show-subordinate-links"
	KeyShowSuccessorLinks   = "show-successor-links"
	// api.KeyLang
)

// Config allows to retrieve all defined configuration values that can be changed during runtime.
type Config interface {
	AuthConfig

id: 00001000000000
title: Zettelstore Manual
role: manual
tags: #manual #zettelstore
syntax: zmk
created: 20210301190630
modified: 20231125185455
show-back-links: false

* [[Introduction|00001001000000]]
* [[Design goals|00001002000000]]
* [[Installation|00001003000000]]
* [[Configuration|00001004000000]]
* [[Structure of Zettelstore|00001005000000]]
* [[Layout of a zettel|00001006000000]]
* [[Zettelmarkup|00001007000000]]
* [[Other markup languages|00001008000000]]
* [[Security|00001010000000]]
* [[API|00001012000000]]
* [[Web user interface|00001014000000]]
* [[Tips and Tricks|00001017000000]]
* [[Troubleshooting|00001018000000]]
* Frequently asked questions

Version: {{00001000000001}}.

Licensed under the EUPL-1.2-or-later.

id: 00001000000001
title: Manual Version
role: configuration
syntax: zmk
created: 20231002142915
modified: 20231002142948

To be set by build tool.

id: 00001004020000
title: Configure the running Zettelstore
role: manual
tags: #configuration #manual #zettelstore
syntax: zmk
created: 20210126175322
modified: 20231126180829
show-back-links: false

You can configure a running Zettelstore by modifying the special zettel with the ID [[00000000000100]].
This zettel is called __configuration zettel__.
The following metadata keys change the appearance / behavior of Zettelstore.
Some of them can be overwritten in an [[user zettel|00001010040200]], a subset of those may be overwritten in zettel that is currently used.
See the full list of [[metadata that may be overwritten|00001004020200]].

; [!default-copyright|''default-copyright'']
: Copyright value to be used when rendering content.
  Can be overwritten in a zettel with [[meta key|00001006020000]] ''copyright''.

  Default: (the empty string).
; [!default-license|''default-license'']
: License value to be used when rendering content.
  Can be overwritten in a zettel with [[meta key|00001006020000]] ''license''.

  Default: (the empty string).
; [!default-visibility|''default-visibility'']
: Visibility to be used, if zettel does not specify a value for the [[''visibility''|00001006020000#visibility]] metadata key.

  Default: ""login"".
; [!expert-mode|''expert-mode'']
: If set to a [[boolean true value|00001006030500]], all zettel with [[visibility ""expert""|00001010070200]] will be shown (to the owner, if [[authentication is enabled|00001010040100]]; to all, otherwise).
  This affects most computed zettel.

  Default: ""False"".
; [!footer-zettel|''footer-zettel'']
: Identifier of a zettel that is rendered as HTML and will be placed as the footer of every zettel in the [[web user interface|00001014000000]].
  Zettel content, delivered via the [[API|00001012000000]] as symbolic expressions, etc. is not affected.
  If the zettel identifier is invalid or references a zettel that could not be read (possibly because of a limited [[visibility setting|00001010070200]]), nothing is written as the footer.

  May be [[overwritten|00001004020200]] in a user zettel.

  Default: (an invalid zettel identifier)
; [!home-zettel|''home-zettel'']
: Specifies the identifier of the zettel, that should be presented for the default view / home view.

  This value is used as a default value, if it is not set in an user's zettel or in a zettel.
  It is also used to specify the language for all non-zettel content, e.g. lists or search results.

  Use values according to the language definition of [[RFC-5646|https://tools.ietf.org/html/rfc5646]].
; [!max-transclusions|''max-transclusions'']
: Maximum number of indirect transclusion.
  This is used to avoid an exploding ""transclusion bomb"", a form of a [[billion laughs attack|https://en.wikipedia.org/wiki/Billion_laughs_attack]].

  Default: ""1024"".
; [!show-back-links|''show-back-links''], [!show-folge-links|''show-folge-links''], [!show-subordinate-links|''show-subordinate-links''], [!show-successor-links|''show-successor-links'']
: When displaying a zettel in the web user interface, references to other zettel are normally shown below the content of the zettel.
  This affects the metadata keys [[''back''|00001006020000#back]], [[''folge''|00001006020000#folge]], [[''subordinates''|00001006020000#subordinates]], and  [[''successors''|00001006020000#successors]].

  These configuration keys may be used to show, not to show, or to close the list of referenced zettel.

  Allowed values are: ""false"" (will not show the list), ""close"" (will show the list closed), and ""open"" / """" (will show the list).

  Default: """".

  May be [[overwritten|00001004020200]] in a user zettel, so that setting will only affect the given user.
  Alternatively, it may be overwritten in a zettel, so that that the setting will affect only the given zettel.

  This zettel is an example of a zettel that sets ''show-back-links'' to ""false"".
; [!site-name|''site-name'']
: Name of the Zettelstore instance.
  Will be used when displaying some lists.

  Default: ""Zettelstore"".
; [!yaml-header|''yaml-header'']
: If [[true|00001006030500]], metadata and content will be separated by ''---\\n'' instead of an empty line (''\\n\\n'').

  Default: ""False"".

  You will probably use this key, if you are working with another software processing [[Markdown|https://daringfireball.net/projects/markdown/]] that uses a subset of [[YAML|https://yaml.org/]] to specify metadata.
; [!zettel-file-syntax|''zettel-file-syntax'']
: If you create a new zettel with a syntax different to ""zmk"", Zettelstore will store the zettel as two files:
  one for the metadata (file without a filename extension) and another for the content (file extension based on the syntax value).
  If you want to specify alternative syntax values, for which you want new zettel to be stored in one file (file extension ''.zettel''), you can use this key.
  All values are case-insensitive, duplicate values are removed.

  For example, you could use this key if you're working with Markdown syntax and you want to store metadata and content in one ''.zettel'' file.

  If ''yaml-header'' evaluates to true, a zettel is always stored in one ''.zettel'' file.

id: 00001004020200
title: Runtime configuration data that may be user specific or zettel specific
role: manual
tags: #configuration #manual #zettelstore
syntax: zmk
created: 20221205155521
modified: 20231126180752

Some metadata of the [[runtime configuration|00001004020000]] may be overwritten in an [[user zettel|00001010040200]].
A subset of those may be overwritten in zettel that is currently used.
This allows to specify user specific or zettel specific behavior.

The following metadata keys are supported to provide a more specific behavior:

|=Key|User:|Zettel:|Remarks
|[[''footer-zettel''|00001004020000#footer-zettel]]|Y|N|
|[[''home-zettel''|00001004020000#home-zettel]]|Y|N|
|[[''lang''|00001004020000#lang]]|Y|Y|Making it user-specific could make zettel for other user less useful
|[[''show-back-links''|00001004020000#show-back-links]]|Y|Y|
|[[''show-folge-links''|00001004020000#show-folge-links]]|Y|Y|
|[[''show-subordinate-links''|00001004020000#show-subordinate-links]]|Y|Y|
|[[''show-successor-links''|00001004020000#show-successor-links]]|Y|Y|

id: 00001005090000
title: List of predefined zettel
role: manual
tags: #manual #reference #zettelstore
syntax: zmk
created: 20210126175322
modified: 20231129173425

The following table lists all predefined zettel with their purpose.

|= Identifier :|= Title | Purpose
| [[00000000000001]] | Zettelstore Version | Contains the version string of the running Zettelstore
| [[00000000000002]] | Zettelstore Host | Contains the name of the computer running the Zettelstore
| [[00000000000003]] | Zettelstore Operating System | Contains the operating system and CPU architecture of the computer running the Zettelstore

| [[00000000010300]] | Zettelstore List Zettel HTML Template | Used when displaying a list of zettel
| [[00000000010401]] | Zettelstore Detail HTML Template | Layout for the HTML detail view of one zettel
| [[00000000010402]] | Zettelstore Info HTML Template | Layout for the information view of a specific zettel
| [[00000000010403]] | Zettelstore Form HTML Template | Form that is used to create a new or to change an existing zettel that contains text
| [[00000000010404]] | Zettelstore Rename Form HTML Template | View that is displayed to change the [[zettel identifier|00001006050000]]
| [[00000000010405]] | Zettelstore Delete HTML Template | View to confirm the deletion of a zettel
| [[00000000010700]] | Zettelstore Error HTML Template | View to show an error message
| [[00000000019000]] | Zettelstore Sxn Start Code | Starting point of sxn functions to build the templates
| [[00000000019990]] | Zettelstore Sxn Base Code | Base sxn functions to build the templates
| [[00000000020001]] | Zettelstore Base CSS | System-defined CSS file that is included by the [[Base HTML Template|00000000010100]]
| [[00000000025001]] | Zettelstore User CSS | User-defined CSS file that is included by the [[Base HTML Template|00000000010100]]

| [[00000000040001]] | Generic Emoji | Image that is shown if [[original image reference|00001007040322]] is invalid
| [[00000000060010]] | zettel | [[Role zettel|00001012051800]] for the role ""[[zettel|00001006020100#zettel]]""
| [[00000000060020]] | confguration | [[Role zettel|00001012051800]] for the role ""[[confguration|00001006020100#confguration]]""
| [[00000000060030]] | role | [[Role zettel|00001012051800]] for the role ""[[role|00001006020100#role]]""
| [[00000000060040]] | tag | [[Role zettel|00001012051800]] for the role ""[[tag|00001006020100#tag]]""
| [[00000000090000]] | New Menu | Contains items that should be in the zettel template menu
| [[00000000090001]] | New Zettel | Template for a new zettel with role ""[[zettel|00001006020100#zettel]]""
| [[00000000090002]] | New User | Template for a new [[user zettel|00001010040200]]
| [[00000000090003]] | New Tag | Template for a new [[tag zettel|00001006020100#tag]]
| [[00000000090004]] | New Role | Template for a new [[role zettel|00001006020100#role]]
| [[00010000000000]] | Home | Default home zettel, contains some welcome information

If a zettel is not linked, it is not accessible for the current user.

**Important:** All identifier may change until a stable version of the software is released.

id: 00001006020100
title: Supported Zettel Roles
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210126175322
modified: 20231129173620

The [[''role'' key|00001006020000#role]] defines what kind of zettel you are writing.
You are free to define your own roles.
It is allowed to set an empty value or to omit the role.

Some roles are defined for technical reasons:

; [!configuration|''configuration'']
: A zettel that contains some configuration data / information for the Zettelstore.
  Most prominent is [[00000000000100]], as described in [[00001004020000]].
; [!manual|''manual'']
: All zettel that document the inner workings of the Zettelstore software.
  This role is only used in this specific Zettelstore.
; [!role|''role'']
: A zettel with the role ""role"" and a title, which names a [[role|00001006020000#role]], is treated as a __role zettel__.
  Basically, role zettel describe the role, and form a hierarchiy of meta-roles.
; [!tag|''tag'']
: A zettel with the role ""tag"" and a title, which names a [[tag|00001006020000#tags]], is treated as a __tag zettel__.
  Basically, tag zettel describe the tag, and form a hierarchiy of meta-tags.
; [!zettel|''zettel'']
: A zettel that contains your own thoughts.
  The real reason to use this software.

If you adhere to the process outlined by Niklas Luhmann, a zettel could have one of the following three roles:

; [!note|''note'']
: A small note, to remember something.
  Notes are not real zettel, they just help to create a real zettel.
  Think of them as Post-it notes.
; [!literature|''literature'']
: Contains some remarks about a book, a paper, a web page, etc.
  You should add a citation key for citing it.
; ''zettel''
: (as described above)

However, you are free to define additional roles, e.g. ''material'' for literature that is web-based only, ''slide'' for presentation slides, ''paper'' for the text of a scientific paper, ''project'' to define a project, ...

id: 00001006034500
title: Timestamp Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20231030182858

Values of this type denote a point in time.

=== Allowed values
Must be a sequence of 4, 6, 8, 10, 12, or 14 digits (""0""--""9"") (similar to an [[Identifier|00001006032000]]), with the restriction that it must conform to the pattern ""YYYYMMDDhhmmss"".

* YYYY is the year,
* MM is the month,
* DD is the day,
* hh is the hour,
* mm is the minute,
* ss is the second.

If the sequence is less than 14 digits, they are expanded with the following rule:


* YYYY is expanded to YYYY0101000000
* YYYYMM is expanded to YYYYMM01000000
* YYYYMMDD is expanded to YYYYMMDD000000
* YYYYMMDDhh is expanded to YYYYMMDDhh0000
* YYYYMMDDhhmm is expanded to YYYYMMDDhhmm00

=== Query comparison
[[Search values|00001007706000]] with more than 14 characters are truncated to contain exactly 14 characters.
Then, they are treated as timestamp data, as describe above, if they contain 4, 6, 8, 10, or 12 digits.

Comparison is done through the string representation.
In case of the search operators ""less"", ""not less"", ""greater"", and ""not greater"", this is the same as a numerical comparison.

=== Sorting
Sorting is done by comparing the possibly expanded values.

id: 00001007030900
title: Zettelmarkup: Comment Blocks
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
created: 20210126175322
modified: 20230807170858

Comment blocks are quite similar to [[verbatim blocks|00001007030500]]: both are used to enter text that should not be interpreted.
While the text entered inside a verbatim block will be processed somehow, text inside a comment block will be ignored[^Well, not completely ignored: text is read, but it will typically not rendered visible.].
Comment blocks are typically used to give some internal comments, e.g. the license of a text or some internal remarks.

Comment blocks begin with at least three percent sign characters (""''%''"", U+0025) at the first position of a line.
You can add some [[attributes|00001007050000]] on the beginning line of a comment block, following the initiating characters.
The comment block supports the default attribute: when given, the text will be rendered, e.g. as an HTML comment.
When rendered to a symbolic expression, the comment block will not be ignored but it will output some text.
Same for other renderer.

Any other character in this line will be ignored

Text following the beginning line will not be interpreted, until a line begins with at least the same number of the same characters given at the beginning line.
This allows to enter some percent sign characters in the text that should not be interpreted.

id: 00001007031140
title: Zettelmarkup: Query Transclusion
role: manual
tags: #manual #search #zettelmarkup #zettelstore
syntax: zmk
created: 20220809132350
modified: 20231023163751

A query transclusion is specified by the following sequence, starting at the first position in a line: ''{{{query:query-expression}}}''.
The line must literally start with the sequence ''{{{query:''.
Everything after this prefix is interpreted as a [[query expression|00001007700000]].

When evaluated, the query expression is evaluated, often resulting in a list of [[links|00001007040310]] to zettel, matching the query expression.
The result replaces the query transclusion element.

: Transform the zettel list into an [[Atom 1.0|https://www.rfc-editor.org/rfc/rfc4287]]-conformant document / feed.
  The document is embedded into the referencing zettel.
; ''RSS'' (aggregate)
: Transform the zettel list into a [[RSS 2.0|https://www.rssboard.org/rss-specification]]-conformant document / feed.
  The document is embedded into the referencing zettel.
; ''KEYS'' (aggregate)
: Emit a list of all metadata keys, together with the number of zettel having the key.
; ''REINDEX'' (aggregate)
: Will be ignored.
  This action may have been copied from an existing [[API query call|00001012051400]] (or from a WebUI query), but is here superfluous (and possibly harmful).
; Any [[metadata key|00001006020000]] of type [[Word|00001006035500]], [[WordSet|00001006036000]], or [[TagSet|00001006034000]] (aggregates)
: Emit an aggregate of the given metadata key.
  The key can be given in any letter case[^Except if the key name collides with one of the above names. In this case use at least one lower case letter.].

Example:
```zmk
{{{query:tags:#search | tags}}}
```
This is a tag cloud of all tags that are used together with the tag #search:
:::example
{{{query:tags:#search | tags}}}
:::

id: 00001007040100
title: Zettelmarkup: Text Formatting
role: manual
tags: #manual #zettelmarkup #zettelstore
syntax: zmk
created: 20210126175322
modified: 20231113191353

Text formatting is the way to make your text visually different.
Every text formatting element begins with two same characters.
It ends when these two same characters occur the second time.
It is possible that some [[attributes|00001007050000]] follow immediately, without any separating character.

Text formatting can be nested, up to a reasonable limit.

* The circumflex accent character (""''^''"", U+005E) allows to enter super-scripted text.
** Example: ``e=mc^^2^^`` is rendered in HTML as: ::e=mc^^2^^::{=example}.
* The comma character (""'',''"", U+002C) produces sub-scripted text.
** Example: ``H,,2,,O`` is rendered in HTML as: ::H,,2,,O::{=example}.
* The quotation mark character (""''"''"", U+0022) marks an inline quotation, according to the [[specified language|00001007050100]].
** Example: ``""To be or not""`` is rendered in HTML as: ::""To be or not""::{=example}.
** Example: ``""Sein oder nicht""{lang=de}`` is rendered in HTML as: ::""Sein oder nicht""{lang=de}::{=example}.
* The number sign (""''#''"", U+0023) marks the text visually, where the mark does not belong to the text itself.
  It is typically used to highlight some text that is important for you, but was not important for the original author.
** Example: ``abc ##def## ghi`` is rendered in HTML as: ::abc ##def## ghi::{=example}.
* The colon character (""'':''"", U+003A) mark some text that should belong together. It fills a similar role as [[region blocks|00001007030800]], but just for inline elements.
** Example: ``abc ::def::{=example} ghi`` is rendered in HTML as: abc ::def::{=example} ghi.

id: 00001007702000
title: Search term
role: manual
tags: #manual #search #zettelstore
syntax: zmk
created: 20220805150154
modified: 20230925173539

A search term allows you to specify one search restriction.
The result [[search expression|00001007700000]], which contains more than one search term, will be the applications of all restrictions.

A search term can be one of the following (the first three term are collectively called __search literals__):
* A metadata-based search, by specifying the name of a [[metadata key|00001006010000]], followed by a [[search operator|00001007705000]], followed by an optional [[search value|00001007706000]].

  A zero value of N will produce the same result as if nothing was specified.
  If specified multiple times, the lower value takes precedence.

  Example: ''PICK 5 PICK 3'' will be interpreted as ''PICK 3''.
* The string ''ORDER'', followed by a non-empty sequence of spaces and the name of a metadata key, will specify an ordering of the result list.
  If you include the string ''REVERSE'' after ''ORDER'' but before the metadata key, the ordering will be reversed.

  Example: ''ORDER published'' will order the resulting list based on the publishing data, while ''ORDER REVERSE published'' will return a reversed result order.

  An explicit order field will take precedence over the random order described below.

  If no random order is effective, a ``ORDER REVERSE id`` will be added.
  This makes the sort stable.

  Example: ``ORDER created`` will be interpreted as ``ORDER created ORDER REVERSE id``.

id: 00001007721200
title: Query: Unlinked Directive
role: manual
tags: #manual #zettelstore
syntax: zmk
created: 20211119133357
modified: 20230928190540

The value of a personal Zettelstore is determined in part by explicit connections between related zettel.
If the number of zettel grow, some of these connections are missing.
There are various reasons for this.
Maybe, you forgot that a zettel exists.
Or you add a zettel later, but forgot that previous zettel already mention its title.

id: 00001007800000
title: Zettelmarkup: Summary of Formatting Characters
role: manual
tags: #manual #reference #zettelmarkup #zettelstore
syntax: zmk
created: 20220805150154
modified: 20231113191330

The following table gives an overview about the use of all characters that begin a markup element.

|= Character :|= [[Blocks|00001007030000]] <|= [[Inlines|00001007040000]] <
| ''!''  | (free) | (free)
| ''"''  | [[Verse block|00001007030700]] | [[Short inline quote|00001007040100]]
| ''#''  | [[Ordered list|00001007030200]] | [[marked / highlighted text|00001007040100]]
| ''$''  | (reserved) | (reserved)
| ''%''  | [[Comment block|00001007030900]] | [[Comment|00001007040000]]
| ''&''  | (free) | [[Entity|00001007040000]]
| ''\'''  | (free)  | [[Computer input|00001007040200]]
| ''(''  | (free) | (free)
| '')''  | (free) | (free)
| ''*''  | [[Unordered list|00001007030200]] | [[strongly emphasized text|00001007040100]]

id: 00001007903000
title: Zettelmarkup: First Steps
role: manual
tags: #manual #tutorial #zettelmarkup #zettelstore
syntax: zmk
created: 20220810182917
modified: 20231201135849

[[Zettelmarkup|00001007000000]] allows you to leave your text as it is, at least in many situations.
Some characters have a special meaning, but you have to enter them is a defined way to see a visible change.
Zettelmarkup is designed to be used for zettel, which are relatively short.
It allows to produce longer texts, but you should probably use a different tool, if you want to produce an scientific paper, to name an example.

=== Paragraphs

| ''An __emphasized__ word'' | An __emphasized__ word | Put two underscore characters before and after the text you want to emphasize
| ''Someone uses **bold** text'' | Someone uses **bold** text | Put two asterisks before and after the text you want to see bold
| ''He says: ""I love you!""'' | Her says: ""I love you!"" | Put two quotation mark characters before and after the text you want to quote.

You probably see a principle.

One nice thing about the quotation mark characters: they are rendered according to the current language.
Examples: ""english""{lang=en}, ""french""{lang=fr}, ""german""{lang=de}.
You will see later, how to change the current language.

=== Lists
Quite often, text consists of lists.
Zettelmarkup supports different types of lists.
The most important lists are:
* Unnumbered lists,

id: 00001007990000
title: Zettelmarkup: Cheat Sheet
role: manual
tags: #manual #reference #zettelmarkup
syntax: zmk
created: 20221209191905
modified: 20231201140000

=== Overview
This Zettelmarkup cheat sheet provides a quick overview of many Zettelmarkup elements.
It can not cover any special case.
If you need more information about any of these elements, please refer to the detailed description.

=== Basic Syntax
|[[Text formatting|00001007040100]]|''__italic text__'' → __italic text__, ''**bold text**'' → **bold text**, ''""quoted text""'' → ""quoted text"", ''##marked text##'' → ##marked text##
|[[Text editing|00001007040100]]|''>>inserted text>>'' → >>inserted text>>, ''~~deleted text~~'' → ~~deleted text~~
|[[Text literal formatting|00001007040200]]|''\'\'entered text\'\''' → ''entered text'', ''``source code``'' → ``source code``, ''==text output=='' → ==text output==
|[[Superscript, subscript|00001007040100]]|''m^^2^^'' → m^^2^^, ''H,,2,,O'' → H,,2,,O
|[[Links to other zettel|00001007040310]]|''[[Link text|00001007990000]]'' → [[Link text|00001007990000]]
|[[Links to external resources|00001007040310]]|''[[Zettelstore|https://zettelstore.de]]'' → [[Zettelstore|https://zettelstore.de]]
|[[Embed an image|00001007040322]]|''{{Image text|00000000040001}}'' → {{Image text|00000000040001}}
|[[Embed content of first paragraph|00001007040324]]|''{{00001007990000}}'' → {{00001007990000}}

id: 00001012000000
title: API
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210126175322
modified: 20231128183617

The API (short for ""**A**pplication **P**rogramming **I**nterface"") is the primary way to communicate with a running Zettelstore.
Most integration with other systems and services is done through the API.
The [[web user interface|00001014000000]] is just an alternative, secondary way of interacting with a Zettelstore.

=== Background
The API is HTTP-based and uses plain text and [[symbolic expressions|00001012930000]] as its main encoding formats for exchanging messages between a Zettelstore and its client software.

There is an [[overview zettel|00001012920000]] that shows the structure of the endpoints used by the API and gives an indication about its use.

=== Authentication
If [[authentication is enabled|00001010040100]], most API calls must include an [[access token|00001010040700]] that proves the identity of the caller.
* [[Authenticate an user|00001012050200]] to obtain an access token
* [[Renew an access token|00001012050400]] without costly re-authentication
* [[Provide an access token|00001012050600]] when doing an API call

=== Zettel lists
* [[List all zettel|00001012051200]]
* [[Query the list of all zettel|00001012051400]]
* [[Determine a tag zettel|00001012051600]]
* [[Determine a role zettel|00001012051800]]

=== Working with zettel
* [[Create a new zettel|00001012053200]]
* [[Retrieve metadata and content of an existing zettel|00001012053300]]
* [[Retrieve metadata of an existing zettel|00001012053400]]
* [[Retrieve evaluated metadata and content of an existing zettel in various encodings|00001012053500]]
* [[Retrieve parsed metadata and content of an existing zettel in various encodings|00001012053600]]

id: 00001012051200
title: API: List all zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210126175322
modified: 20230807170810

To list all zettel just send a HTTP GET request to the [[endpoint|00001012920000]] ''/z''[^If [[authentication is enabled|00001010040100]], you must include the a valid [[access token|00001012050200]] in the ''Authorization'' header].
Always use the endpoint ''/z'' to work with a list of zettel.

Without further specifications, a plain text document is returned, with one line per zettel.
Each line contains in the first 14 characters the [[zettel identifier|00001006050000]].
Separated by a space character, the title of the zettel follows:

* Keys ''query'' and ''human'' will be explained [[later in this manual|00001012051400]].
* ''list'' starts a list of zettel.
* ''zettel'' itself start, well, a zettel.
* ''id'' denotes the zettel identifier, encoded as a string.
* Nested in ''meta'' are the metadata, each as a key/value pair.
* ''rights'' specifies the [[access rights|00001012921200]] the user has for this zettel.


































































































=== Note
This request (and similar others) will always return a list of metadata, provided the request was syntactically correct.
There will never be a HTTP status code 403 (Forbidden), even if [[authentication was enabled|00001010040100]] and you did not provide a valid access token.
In this case, the resulting list might be quite short (some zettel will have [[public visibility|00001010070200]]) or the list might be empty.

With this call, you cannot differentiate between an empty result list (e.g because your search did not found a zettel with the specified term) and an empty list because of missing authorization (e.g. an invalid access token).

=== HTTP Status codes
; ''200''
: Retrieval was successful, the body contains an appropriate data value.
; ''400''
: Request was not valid. 
  There are several reasons for this.
  Maybe the access bearer token was not valid.

id: 00001012051400
title: API: Query the list of all zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20220912111111
modified: 20231023162927
precursor: 00001012051200

The [[endpoint|00001012920000]] ''/z'' also allows you to filter the list of all zettel[^If [[authentication is enabled|00001010040100]], you must include the a valid [[access token|00001012050200]] in the ''Authorization'' header] and optionally to provide some actions.

A [[query|00001007700000]] is an optional [[search expression|00001007700000#search-expression]], together with an optional [[list of actions|00001007700000#action-list]] (described below).
An empty search expression will select all zettel.
An empty list of action, or no valid action, returns the list of all selected zettel metadata.

Search expression and action list are separated by a vertical bar character (""''|''"", U+007C), and must be given with the query parameter ''q''.

The query parameter ""''q''"" allows you to specify [[query expressions|00001007700000]] for a full-text search of all zettel content and/or restricting the search according to specific metadata.

It is allowed to specify this query parameter more than once.

This parameter loosely resembles the search form of the [[web user interface|00001014000000]] or those of [[Zettelmarkup's Query Transclusion|00001007031140]].

For example, if you want to retrieve all zettel that contain the string ""API"" in its title, your request will be:
```sh
# curl 'http://127.0.0.1:23123/z?q=title%3AAPI+ORDER+REVERSE+id+OFFSET+1'
00001012921000 API: Structure of an access token
00001012920500 Formats available by the API
00001012920000 Endpoints used by the API
...
```

If you want to retrieve a data document, as a [[symbolic expression|00001012930500]]:

```sh
# curl 'http://127.0.0.1:23123/z?q=title%3AAPI+ORDER+REVERSE+id+OFFSET+1&enc=data'
(meta-list (query "title:API ORDER REVERSE id OFFSET 1") (human "title HAS API ORDER REVERSE id OFFSET 1") (list (zettel (id 1012921000) (meta (title "API: Structure of an access token") (role "manual") (tags "#api #manual #reference #zettelstore") (syntax "zmk") (back "00001012050600 00001012051200") (backward "00001012050200 00001012050400 00001012050600 00001012051200") (box-number "1") (created "20210126175322") (forward "00001012050200 00001012050400 00001012930000") (modified "20230412155303") (published "20230412155303")) (rights 62)) (zettel (id 1012920500) (meta (title "Encodings available via the API") (role "manual") (tags "#api #manual #reference #zettelstore") (syntax "zmk") (back "00001006000000 00001008010000 00001008010500 00001012053500 00001012053600") (backward "00001006000000 00001008010000 00001008010500 00001012053500 00001012053600") (box-number "1") (created "20210126175322") (forward "00001012000000 00001012920510 00001012920513 00001012920516 00001012920519 00001012920522 00001012920525") (modified "20230403123653") (published "20230403123653")) (rights 62)) (zettel (id 1012920000) (meta (title "Endpoints used by the API") ...
```

The data object contains a key ''"meta-list"'' to signal that it contains a list of metadata values (and some more).
It contains the keys ''"query"'' and ''"human"'' with a string value.
Both will contain a textual description of the underlying query if you select only some zettel with a [[query expression|00001007700000]].
Without a selection, the values are the empty string.
''"query"'' returns the normalized query expression itself, while ''"human"'' is the normalized query expression to be read by humans.


The symbol ''list'' starts the list of zettel data.
Data of a zettel is indicated by the symbol ''zettel'', followed by ''(id ID)'' that describes the zettel identifier as a numeric value.
Leading zeroes are removed.
Metadata starts with the symbol ''meta'', and each metadatum itself is a list of metadata key / metadata value.
Metadata keys are encoded as a symbol, metadata values as a string.
''"rights"'' encodes the [[access rights|00001012921200]] for the given zettel.














=== Aggregates

An implicit precondition is that the zettel must contain the given metadata key.
For a metadata key like [[''title''|00001006020000#title]], which have a default value, this precondition should always be true.
But the situation is different for a key like [[''url''|00001006020000#url]].
Both ``curl 'http://localhost:23123/z?q=url%3A'`` and ``curl 'http://localhost:23123/z?q=url%3A!'`` may result in an empty list.

# curl 'http://127.0.0.1:23123/z?q=|tags&enc=data'
(aggregate "tags" (query "| tags") (human "| tags") (list ("#zettel" 1006034500 1006034000 1006031000 1006020400 1006033500 1006036500 1006032500 1006020100 1006031500 1006030500 1006035500 1006033000 1006020000 1006036000 1006030000 1006032000 1006035000) ("#reference" 1006034500 1006034000 1007800000 1012920500 1006031000 1012931000 1006020400 1012930000 1006033500 1012920513 1007050100 1012920800 1007780000 1012921000 1012920510 1007990000 1006036500 1006032500 1006020100 1012931400 1012931800 1012920516 1012931600 1012920525 1012931200 1006031500 1012931900 1012920000 1005090000 1012920522 1006030500 1007050200 1012921200 1006035500 1012920519 1006033000 1006020000 1006036000 1006030000 1006032000 1012930500 1006035000) ("#graphic" 1008050000) ("#search" 1007700000 1007705000 1007790000 1007780000 1007702000 1007706000 1007031140) ("#installation" 1003315000 1003310000 1003000000 1003305000 1003300000 1003600000) ("#zettelmarkup" 1007900000 1007030700 1007031300 1007030600 1007800000 1007000000 1007031400 1007040100 1007030300 1007031200 1007040350 1007030400 1007030900 1007050100 1007040000 1007030500 1007903000 1007040200 1007040330 1007990000 1007040320 1007050000 1007040310 1007031100 1007040340 1007020000 1007031110 1007031140 1007040324 1007030800 1007031000 1007030000 1007010000 1007906000 1007050200 1007030100 1007030200 1007040300 1007040322) ("#design" 1005000000 1006000000 1002000000 1006050000 1006055000) ("#markdown" 1008010000 1008010500) ("#goal" 1002000000) ("#syntax" 1006010000) ...
```

If you want only those tags that occur at least 100 times, use the endpoint ''/z?q=|MIN100+tags''.
You see from this that actions are separated by space characters.






















=== Actions

There are two types of actions: parameters and aggregates.
The following actions are supported:
; ''MINn'' (parameter)
: Emit only those values with at least __n__ aggregated values.
  __n__ must be a positive integer, ''MIN'' must be given in upper-case letters.
; ''MAXn'' (parameter)
: Emit only those values with at most __n__ aggregated values.
  __n__ must be a positive integer, ''MAX'' must be given in upper-case letters.
; ''REINDEX'' (aggregate)
: Updates the internal search index for the selected zettel, roughly similar to the [[refresh|00001012080500]] API call.
  It is not really an aggregate, since it is used only for its side effect.
  It is allowed to specify another aggregate.
; Any [[metadata key|00001006020000]] of type [[Word|00001006035500]], [[WordSet|00001006036000]], or [[TagSet|00001006034000]] (aggregates)
: Emit an aggregate of the given metadata key.
  The key can be given in any letter case.

Only the first aggregate action will be executed.

id: 00001012051600
title: API: Determine a tag zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20230928183339
modified: 20230929114937

The [[endpoint|00001012920000]] ''/z'' also allows you to determine a ""tag zettel"", i.e. a zettel that documents a given tag.

The query parameter ""''tag''"" allows you to specify a value that is interpreted as the name of a tag.
Zettelstore tries to determine the corresponding tag zettel.

A tag zettel is a zettel with the [[''role''|00001006020100]] value ""tag"" and a title that names the tag.
If there is more than one zettel that qualifies, the zettel with the highest zettel identifier is used.

For example, if you want to determine the tag zettel for the tag ""#api"", your request will be:
```sh
# curl -i 'http://127.0.0.1:23123/z?tag=%23api'
HTTP/1.1 302 Found
Content-Type: text/plain; charset=utf-8
Location: /z/00001019990010
Content-Length: 14

00001019990010
```

Alternatively, you can omit the ''#'' character at the beginning of the tag:
```sh
# curl -i 'http://127.0.0.1:23123/z?tag=api'
HTTP/1.1 302 Found
Content-Type: text/plain; charset=utf-8
Location: /z/00001019990010
Content-Length: 14

00001019990010
```

If there is a corresponding tag zettel, the response will use the HTTP status code 302 (""Found""), the HTTP response header ''Location'' will contain the URL of the tag zettel.
Its zettel identifier will be returned in the HTTP response body.

If you specified some more query parameter, these will be part of the URL in the response header ''Location'':

```sh
# curl -i 'http://127.0.0.1:23123/z?tag=%23api&part=zettel'
HTTP/1.1 302 Found
Content-Type: text/plain; charset=utf-8
Location: /z/00001019990010?part=zettel
Content-Length: 14

00001019990010
```

Otherwise, if no tag zettel was found, the response will use the HTTP status code 404 (""Not found"").

```sh
# curl -i 'http://127.0.0.1:23123/z?tag=notag'
HTTP/1.1 404 Not Found
Content-Type: text/plain; charset=utf-8
Content-Length: 29

Tag zettel not found: #notag
```

To fulfill this service, Zettelstore will evaluate internally the query ''role:tag title=TAG'', there ''TAG'' is the actual tag.

Of course, if you are interested in the URL of the tag zettel, you can make use of the HTTP ''HEAD'' method:

```sh
# curl -I 'http://127.0.0.1:23123/z?tag=%23api'
HTTP/1.1 302 Found
Content-Type: text/plain; charset=utf-8
Location: /z/00001019990010
Content-Length: 14
```

=== HTTP Status codes
; ''302''
: Tag zettel was found.
  The HTTP header ''Location'' contains its URL, the body of the response contains its zettel identifier.
; ''404''
: No zettel for the given tag was found.

id: 00001012051800
title: API: Determine a role zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20231128183917
modified: 20231128184701

The [[endpoint|00001012920000]] ''/z'' also allows you to determine a ""role zettel"", i.e. a zettel that documents a given role.

The query parameter ""''role''"" allows you to specify a value that is interpreted as the name of a role.
Zettelstore tries to determine the corresponding role zettel.

A role zettel is a zettel with the [[''role''|00001006020100]] value ""role"" and a title that names the role.
If there is more than one zettel that qualifies, the zettel with the highest zettel identifier is used.

For example, if you want to determine the role zettel for the role ""manual"", your request will be:
```sh
# curl -i 'http://127.0.0.1:23123/z?role=manual'
HTTP/1.1 302 Found
Content-Type: text/plain; charset=utf-8
Location: /z/20231128184200
Content-Length: 14

20231128184200
```

If there is a corresponding role zettel, the response will use the HTTP status code 302 (""Found""), the HTTP response header ''Location'' will contain the URL of the role zettel.
Its zettel identifier will be returned in the HTTP response body.

If you specified some more query parameter, these will be part of the URL in the response header ''Location'':

```sh
# curl -i 'http://127.0.0.1:23123/z?role=manual&part=zettel'
HTTP/1.1 302 Found
Content-Type: text/plain; charset=utf-8
Location: /z/20231128184200?part=zettel
Content-Length: 14

20231128184200
```

Otherwise, if no role zettel was found, the response will use the HTTP status code 404 (""Not found"").

```sh
# curl -i 'http://127.0.0.1:23123/z?role=norole'
HTTP/1.1 404 Not Found
Content-Type: text/plain; charset=utf-8
Content-Length: 30

Role zettel not found: norole
```

To fulfill this service, Zettelstore will evaluate internally the query ''role:role title=ROLE'', there ''ROLE'' is the actual role.

Of course, if you are only interested in the URL of the role zettel, you can make use of the HTTP ''HEAD'' method:

```sh
# curl -I 'http://127.0.0.1:23123/z?role=manual'
HTTP/1.1 302 Found
Content-Type: text/plain; charset=utf-8
Location: /z/20231128184200
Content-Length: 14
```

=== HTTP Status codes
; ''302''
: Role zettel was found.
  The HTTP header ''Location'' contains its URL, the body of the response contains its zettel identifier.
; ''404''
: No zettel for the given role was found.

id: 00001012053200
title: API: Create a new zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210713150005
modified: 20230807170416

A zettel is created by adding it to the [[list of zettel|00001012000000]].
Therefore, the [[endpoint|00001012920000]] to create a new zettel is also ''/z'', but you must send the data of the new zettel via a HTTP POST request.


The zettel must be encoded in a [[plain|00001006000000]] format: first comes the [[metadata|00001006010000]] and the following content is separated by an empty line.
This is the same format as used by storing zettel within a [[directory box|00001006010000]].

=== Data input
Alternatively, you may encode the zettel as a parseable object / a [[symbolic expression|00001012930500]] by providing the query parameter ''enc=data''.
The encoding is the same as the data output encoding when you [[retrieve a zettel|00001012053300#data-output]].

The encoding for [[access rights|00001012921200]] must be given, but is ignored.
You may encode computed or property [[metadata keys|00001006020000]], but these are also ignored.






































=== HTTP Status codes
; ''201''
: Zettel creation was successful, the body contains its [[zettel identifier|00001006050000]] (data value or plain text).
; ''400''
: Request was not valid. 
  There are several reasons for this.
  Most likely, the symbolic expression was not formed according to above rules.
; ''403''
: You are not allowed to create a new zettel.

id: 00001012053300
title: API: Retrieve metadata and content of an existing zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20211004093206
modified: 20230807170259

The [[endpoint|00001012920000]] to work with metadata and content of a specific zettel is ''/z/{ID}'', where ''{ID}'' is a placeholder for the [[zettel identifier|00001006050000]].

For example, to retrieve some data about this zettel you are currently viewing, just send a HTTP GET request to the endpoint ''/z/00001012053300''[^If [[authentication is enabled|00001010040100]], you must include the a valid [[access token|00001012050200]] in the ''Authorization'' header].

````sh
# curl 'http://127.0.0.1:23123/z/00001012053300'

* Nested in ''meta'' are the metadata, each as a key/value pair.
* ''rights'' specifies the [[access rights|00001012921200]] the user has for this zettel.
* ''"encoding"'' states how the content is encoded.
  Currently, only two values are allowed: the empty string (''""'') that specifies an empty encoding, and the string ''"base64"'' that specifies the [[standard Base64 encoding|https://www.rfc-editor.org/rfc/rfc4648.txt]].
* The zettel contents is stored as a value of the key ''content''.
  Typically, text content is not encoded, and binary content is encoded via Base64.
















































=== HTTP Status codes
; ''200''
: Retrieval was successful, the body contains an appropriate data value.
; ''204''
: Request was valid, but there is no data to be returned.
  Most likely, you specified the query parameter ''part=content'', but the zettel does not contain any content.
; ''400''
: Request was not valid. 
  There are several reasons for this.
  Maybe the [[zettel identifier|00001006050000]] did not consists of exactly 14 digits.
; ''403''
: You are not allowed to retrieve data of the given zettel.
; ''404''
: Zettel not found.
  You probably used a zettel identifier that is not used in the Zettelstore.

id: 00001012053400
title: API: Retrieve metadata of an existing zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210726174524
modified: 20230807170155

The [[endpoint|00001012920000]] to work with metadata of a specific zettel is ''/z/{ID}'', where ''{ID}'' is a placeholder for the [[zettel identifier|00001006050000]][^If [[authentication is enabled|00001010040100]], you must include the a valid [[access token|00001012050200]] in the ''Authorization'' header].

To retrieve the plain metadata of a zettel, use the query parameter ''part=meta''

````sh
# curl 'http://127.0.0.1:23123/z/00001012053400?part=meta'

      (rights 62))
```

* The result is a list, starting with the symbol ''list''.
* Then, some key/value pairs are following, also nested.
* Nested in ''meta'' are the metadata, each as a key/value pair.
* ''rights'' specifies the [[access rights|00001012921200]] the user has for this zettel.





































=== HTTP Status codes
; ''200''
: Retrieval was successful, the body contains an appropriate data value.
; ''400''
: Request was not valid. 
  There are several reasons for this.
  Maybe the zettel identifier did not consist of exactly 14 digits.
; ''403''
: You are not allowed to retrieve data of the given zettel.
; ''404''
: Zettel not found.
  You probably used a zettel identifier that is not used in the Zettelstore.

id: 00001012053500
title: API: Retrieve evaluated metadata and content of an existing zettel in various encodings
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210726174524
modified: 20230807170112

The [[endpoint|00001012920000]] to work with evaluated metadata and content of a specific zettel is ''/z/{ID}'', where ''{ID}'' is a placeholder for the [[zettel identifier|00001006050000]].

For example, to retrieve some evaluated data about this zettel you are currently viewing in [[Sz encoding|00001012920516]], just send a HTTP GET request to the endpoint ''/z/00001012053500''[^If [[authentication is enabled|00001010040100]], you must include the a valid [[access token|00001012050200]] in the ''Authorization'' header] with the query parameter ''enc=sz''.
If successful, the output is a symbolic expression value:
```sh
# curl 'http://127.0.0.1:23123/z/00001012053500?enc=sz'
((PARA (TEXT "The") (SPACE) (LINK-ZETTEL () "00001012920000" (TEXT "endpoint")) (SPACE) (TEXT "to") (SPACE) (TEXT "work") (SPACE) (TEXT "with") (SPACE) (TEXT "evaluated") (SPACE) (TEXT "metadata") (SPACE) (TEXT "and") (SPACE) (TEXT "content") (SPACE) (TEXT "of") (SPACE) (TEXT "a") (SPACE) (TEXT "specific") (SPACE) (TEXT "zettel") (SPACE) (TEXT "is") (SPACE) (LITERAL-INPUT () "/z/{ID}") (TEXT ",") (SPACE) (TEXT "where") (SPACE) (LITERAL-INPUT () "{ID}") ...
```

To select another encoding, you must provide the query parameter ''enc=ENCODING''.
Others are ""[[html|00001012920510]]"", ""[[text|00001012920519]]"", and some [[more|00001012920500]].

<h1>API: Retrieve evaluated metadata and content of an existing zettel in various encodings</h1>
<p>The <a href="00001012920000">endpoint</a> to work with evaluated metadata and content of a specific zettel is <kbd>/z/{ID}</kbd>,
...
```

=== HTTP Status codes
; ''200''
: Retrieval was successful, the body contains an appropriate data value.
; ''400''
: Request was not valid. 
  There are several reasons for this.
  Maybe the zettel identifier did not consist of exactly 14 digits or ''enc'' / ''part'' contained illegal values.
; ''403''
: You are not allowed to retrieve data of the given zettel.
; ''404''
: Zettel not found.
  You probably used a zettel identifier that is not used in the Zettelstore.

id: 00001012053600
title: API: Retrieve parsed metadata and content of an existing zettel in various encodings
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210126175322
modified: 20230807170019

The [[endpoint|00001012920000]] to work with parsed metadata and content of a specific zettel is ''/z/{ID}'', where ''{ID}'' is a placeholder for the [[zettel identifier|00001006050000]].

A __parsed__ zettel is basically an [[unevaluated|00001012053500]] zettel: the zettel is read and analyzed, but its content is not __evaluated__.
By using this endpoint, you are able to retrieve the structure of a zettel before it is evaluated.

For example, to retrieve some data about this zettel you are currently viewing, just send a HTTP GET request to the endpoint ''/z/00001012053600''[^If [[authentication is enabled|00001010040100]], you must include the a valid [[access token|00001012050200]] in the ''Authorization'' header] with the query parameter ''parseonly'' (and other appropriate query parameter).
For example:
```sh
# curl 'http://127.0.0.1:23123/z/00001012053600?enc=sz&parseonly'
((PARA (TEXT "The") (SPACE) (LINK-ZETTEL () "00001012920000" (TEXT "endpoint")) (SPACE) (TEXT "to") (SPACE) (TEXT "work") (SPACE) (TEXT "with") (SPACE) ...
```

Similar to [[retrieving an encoded zettel|00001012053500]], you can specify an [[encoding|00001012920500]] and state which [[part|00001012920800]] of a zettel you are interested in.
The same default values applies to this endpoint.

=== HTTP Status codes
; ''200''
: Retrieval was successful, the body contains an appropriate data value.
; ''400''
: Request was not valid. 
  There are several reasons for this.
  Maybe the zettel identifier did not consist of exactly 14 digits or ''enc'' / ''part'' contained illegal values.
; ''403''
: You are not allowed to retrieve data of the given zettel.
; ''404''
: Zettel not found.
  You probably used a zettel identifier that is not used in the Zettelstore.

id: 00001012054200
title: API: Update a zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210713150005
modified: 20231116110417

Updating metadata and content of a zettel is technically quite similar to [[creating a new zettel|00001012053200]].
In both cases you must provide the data for the new or updated zettel in the body of the HTTP request.

One difference is the endpoint.
The [[endpoint|00001012920000]] to update a zettel is ''/z/{ID}'', where ''{ID}'' is a placeholder for the [[zettel identifier|00001006050000]].
You must send a HTTP PUT request to that endpoint.

The zettel must be encoded in a [[plain|00001006000000]] format: first comes the [[metadata|00001006010000]] and the following content is separated by an empty line.
This is the same format as used by storing zettel within a [[directory box|00001006010000]].

```
# curl -X PUT --data $'title: Updated Note\n\nUpdated content.' http://127.0.0.1:23123/z/00001012054200
```

=== Data input
Alternatively, you may encode the zettel as a parseable object / a [[symbolic expression|00001012930500]] by providing the query parameter ''enc=data''.
The encoding is the same as the data output encoding when you [[retrieve a zettel|00001012053300#data-output]].

The encoding for [[access rights|00001012921200]] must be given, but is ignored.
You may encode computed or property [[metadata keys|00001006020000]], but these are also ignored.












=== HTTP Status codes
; ''204''
: Update was successful, there is no body in the response.
; ''400''
: Request was not valid.
  For example, the request body was not valid.
; ''403''
: You are not allowed to delete the given zettel.
; ''404''
: Zettel not found.
  You probably used a zettel identifier that is not used in the Zettelstore.

id: 00001012070500
title: API: Retrieve administrative data
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20220304164242
modified: 20230928190516

The [[endpoint|00001012920000]] ''/x'' allows you to retrieve some (administrative) data.

Currently, you can only request Zettelstore version data.

````
# curl 'http://127.0.0.1:23123/x'

id: 00001012921000
title: API: Structure of an access token
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
created: 20210126175322
modified: 20230807165915

If the [[authentication process|00001012050200]] was successful, an access token with some additional data is returned.
The same is true, if the access token was [[renewed|00001012050400]].
The response is structured as a [[symbolic expression|00001012930000]] list, with the following elements:

# The type of the token, always set to ''"Bearer"'', as described in [[RFC 6750|https://tools.ietf.org/html/rfc6750]]
# The token itself, which is technically the string representation of a [[symbolic expression|00001012930500]] containing relevant data, plus a check sum.
#* The symbolic expression has the form ''(KIND USERNAME NOW EXPIRE Z-ID)''
#* ''KIND'' is ''0'' for an API access, ''1'' if it created for the Web user interface.
#* ''USERNAME'' is the user name of the user.
#* ''NOW'' is a timestamp of the current time.
#* ''EXPIRE'' is the timestamp when the access token expires.
#* ''Z-ID'' is the zettel identifier of the user zettel.
  The symbolic expression is encoded via ""base64"".
  Based on this encoding, a checksum is calculated, also encoded via ""base64"".
  Both encoded values are concatenated, with a period (''"."'') as a delimiter.

id: 00001012921200
title: API: Encoding of Zettel Access Rights
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
created: 20220201173115
modified: 20230807164817

Various API calls return a symbolic expression list ''(rights N)'', with ''N'' as a number, that encodes the access rights the user currently has.
''N'' is an integer number between 0 and 62.[^Not all values in this range are used.]

The value ""0"" signals that something went wrong internally while determining the access rights.

A value of ""1"" says, that the current user has no access right for the given zettel.
In most cases, this value will not occur, because only zettel are presented, which are at least readable by the current user.

Values ""2"" to ""62"" are binary encoded values, where each bit signals a special right.

id: 00001012931600
title: Encoding of Sz Inline Elements
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
created: 20230403161845
modified: 20231113191203

=== ''TEXT''
:::syntax
__Text__ **=** ''(TEXT'' String '')''.
:::
Specifies the string as some text content, typically a word.

The inline text should be treated as emphasized.

:::syntax
__InsertFormat__ **=** ''(FORMAT-INSERT'' [[__Attributes__|00001012931000#attribute]] [[__InlineElement__|00001012931600]] … '')''.
:::
The inline text should be treated as inserted.

:::syntax
__MarkFormat__ **=** ''(FORMAT-MARK'' [[__Attributes__|00001012931000#attribute]] [[__InlineElement__|00001012931600]] … '')''.
:::
The inline text should be treated as highlighted for the reader (but was not important fto the original author).

:::syntax
__QuoteFormat__ **=** ''(FORMAT-QUOTE'' [[__Attributes__|00001012931000#attribute]] [[__InlineElement__|00001012931600]] … '')''.
:::
The inline text should be treated as quoted text.

:::syntax
__SpanFormat__ **=** ''(FORMAT-SPAN'' [[__Attributes__|00001012931000#attribute]] [[__InlineElement__|00001012931600]] … '')''.

id: 00001017000000
title: Tips and Tricks
role: manual
tags: #manual #zettelstore
syntax: zmk
created: 20220803170112
modified: 20231012154803

=== Welcome Zettel
* **Problem:** You want to put your Zettelstore into the public and need a starting zettel for your users.
  In addition, you still want a ""home zettel"", with all your references to internal, non-public zettel.
  Zettelstore only allows to specify one [[''home-zettel''|00001004020000#home-zettel]].
* **Solution 1:**
*# Create a new zettel with all your references to internal, non-public zettel.

  If multiple user should use the same home zettel, its zettel identifier must be set in all relevant user zettel.

=== Role-specific Layout of Zettel in Web User Interface (WebUI)
[!role-css]
* **Problem:** You want to add some CSS when displaying zettel of a specific [[role|00001006020000#role]].
  For example, you might want to add a yellow background color for all [[configuration|00001006020100#configuration]] zettel.
  Or you want a multi-column layout.
* **Solution:** If you enable [[''expert-mode''|00001004020000#expert-mode]], you will have access to a zettel called ""[[Zettelstore Sxn Start Code|00000000019000]]"" (its identifier is ''00000000019000'').
  This zettel is the starting point for Sxn code, where you can place a definition for a variable named ""CSS-ROLE-map"".

  But first, create a zettel containing the needed CSS: give it any title, its role is preferably ""configuration"" (but this is not a must).
  Its [[''syntax''|00001006020000#syntax]] must be set to ""[[css|00001008000000#css]]"".
  The content must contain the role-specific CSS code, for example ``body {background-color: #FFFFD0}``for a background in a light yellow color.

  Let's assume, the newly created CSS zettel got the identifier ''20220825200100''.

  Now, you have to map this freshly created zettel to a role, for example ""zettel"".
  Since you have enabled ''expert-mode'', you are allowed to modify the zettel ""[[Zettelstore Sxn Start Code|00000000019000]]"".
  Add the following code to the Sxn Start Code zettel: ``(set! CSS-ROLE-map '(("zettel" . "20220825200100")))``.

  In general, the mapping must follow the pattern: ``(ROLE . ID)``, where ''ROLE'' is the placeholder for the role, and ''ID'' for the zettel identifier containing CSS code.
  For example, if you also want the role ""configuration"" to be rendered using that CSS, the code should be something like ``(set! CSS-ROLE-map '(("zettel" . "20220825200100") ("configuration" . "20220825200100")))``.
* **Discussion:** you have to ensure that the CSS zettel is allowed to be read by the intended audience of the zettel with that given role.
  For example, if you made zettel with a specific role public visible, the CSS zettel must also have a [[''visibility: public''|00001010070200]] metadata.


=== Zettel synchronization with iCloud (Apple)
* **Problem:** You use Zettelstore on various macOS computers and you want to use the sameset of zettel across all computers.
* **Solution:** Place your zettel in an iCloud folder.

  To configure Zettelstore to use the folder, you must specify its location within you directory structure as [[''box-uri-X''|00001004010000#box-uri-x]] (replace ''X'' with an appropriate number).
  Your iCloud folder is typically placed in the folder ''~/Library/Mobile Documents/com~apple~CloudDocs''.

id: 00001019990010
title: #api
role: tag
syntax: zmk
created: 20230928185004
modified: 20230928185204

Zettel with the tag ''#api'' contain a description of the [[API|00001012000000]].

id: 20231128184200
title: manual
role: role
syntax: zmk
created: 20231128184200

Zettel with the role ""manual"" contain the manual of the zettelstore.

	ErrNoWriteMeta    = errors.New("method WriteMeta is not implemented")
	ErrNoWriteContent = errors.New("method WriteContent is not implemented")
	ErrNoWriteBlocks  = errors.New("method WriteBlocks is not implemented")
	ErrNoWriteInlines = errors.New("method WriteInlines is not implemented")
)

// Create builds a new encoder with the given options.
func Create(enc api.EncodingEnum, params *CreateParameter) Encoder {
	if create, ok := registry[enc]; ok {
		return create(params)
	}
	return nil
}

// CreateFunc produces a new encoder.
type CreateFunc func(*CreateParameter) Encoder

// CreateParameter contains values that are needed to create an encoder.
type CreateParameter struct {
	Lang string // default language
}

var registry = map[api.EncodingEnum]CreateFunc{}

// Register the encoder for later retrieval.
func Register(enc api.EncodingEnum, create CreateFunc) {
	if _, ok := registry[enc]; ok {
		panic(fmt.Sprintf("Encoder %q already registered", enc))

			encoderMD:    "",
			encoderSz:    `(BLOCK (DESCRIPTION (INLINE (TEXT "Zettel")) (BLOCK (BLOCK (PARA (TEXT "Paper")) (PARA (TEXT "Note")))) (INLINE (TEXT "Zettelkasten")) (BLOCK (BLOCK (PARA (TEXT "Slip") (SPACE) (TEXT "box"))))))`,
			encoderSHTML: `((dl (dt "Zettel") (dd (p "Paper") (p "Note")) (dt "Zettelkasten") (dd (p "Slip" " " "box"))))`,
			encoderText:  "Zettel\nPaper\nNote\nZettelkasten\nSlip box",
			encoderZmk:   useZmk,
		},
	},
	{
		descr: "Description List with keys, but no descriptions",
		zmk:   "; K1\n: D11\n: D12\n; K2\n; K3\n: D31",
		expect: expectMap{
			encoderHTML:  "<dl><dt>K1</dt><dd><p>D11</p></dd><dd><p>D12</p></dd><dt>K2</dt><dt>K3</dt><dd><p>D31</p></dd></dl>",
			encoderMD:    "",
			encoderSz:    `(BLOCK (DESCRIPTION (INLINE (TEXT "K1")) (BLOCK (BLOCK (PARA (TEXT "D11"))) (BLOCK (PARA (TEXT "D12")))) (INLINE (TEXT "K2")) (BLOCK) (INLINE (TEXT "K3")) (BLOCK (BLOCK (PARA (TEXT "D31"))))))`,
			encoderSHTML: `((dl (dt "K1") (dd (p "D11")) (dd (p "D12")) (dt "K2") (dt "K3") (dd (p "D31"))))`,
			encoderText:  "K1\nD11\nD12\nK2\nK3\nD31",
			encoderZmk:   useZmk,
		},
	},
	{
		descr: "Simple Table",
		zmk:   "|c1|c2|c3\n|d1||d3",
		expect: expectMap{
			encoderHTML:  `<table><tbody><tr><td>c1</td><td>c2</td><td>c3</td></tr><tr><td>d1</td><td></td><td>d3</td></tr></tbody></table>`,
			encoderMD:    "",
			encoderSz:    `(BLOCK (TABLE () (list (CELL (TEXT "c1")) (CELL (TEXT "c2")) (CELL (TEXT "c3"))) (list (CELL (TEXT "d1")) (CELL) (CELL (TEXT "d3")))))`,

			encoderZmk:   useZmk,
		},
	},
	{
		descr: "Quotes formatting",
		zmk:   `""quotes""`,
		expect: expectMap{
			encoderHTML:  "“quotes”",
			encoderMD:    "<q>quotes</q>",
			encoderSz:    `(INLINE (FORMAT-QUOTE () (TEXT "quotes")))`,
			encoderSHTML: `((@L (@H "&ldquo;") "quotes" (@H "&rdquo;")))`,
			encoderText:  `quotes`,
			encoderZmk:   useZmk,
		},
	},
	{
		descr: "Quotes formatting (german)",
		zmk:   `""quotes""{lang=de}`,
		expect: expectMap{
			encoderHTML:  `<span lang="de">&bdquo;quotes&ldquo;</span>`,
			encoderMD:    "<q>quotes</q>",
			encoderSz:    `(INLINE (FORMAT-QUOTE (quote (("lang" . "de"))) (TEXT "quotes")))`,
			encoderSHTML: `((span (@ (lang . "de")) (@H "&bdquo;") "quotes" (@H "&ldquo;")))`,
			encoderText:  `quotes`,
			encoderZmk:   `""quotes""{lang="de"}`,
		},
	},
	{
		descr: "Empty quotes (default)",
		zmk:   `""""`,
		expect: expectMap{
			encoderHTML:  `&ldquo;&rdquo;`,
			encoderMD:    "<q></q>",
			encoderSz:    `(INLINE (FORMAT-QUOTE ()))`,
			encoderSHTML: `((@L (@H "&ldquo;" "&rdquo;")))`,
			encoderText:  ``,
			encoderZmk:   useZmk,
		},
	},
	{
		descr: "Empty quotes (unknown)",
		zmk:   `""""{lang=unknown}`,
		expect: expectMap{
			encoderHTML:  `<span lang="unknown">&quot;&quot;</span>`,
			encoderMD:    "<q></q>",
			encoderSz:    `(INLINE (FORMAT-QUOTE (quote (("lang" . "unknown")))))`,
			encoderSHTML: `((span (@ (lang . "unknown")) (@H "&quot;" "&quot;")))`,
			encoderText:  ``,
			encoderZmk:   `""""{lang="unknown"}`,
		},
	},
	{
		descr: "Nested quotes (default)",
		zmk:   `""say: ::""yes, ::""or?""::""::""`,
		expect: expectMap{
			encoderHTML:  `&ldquo;say: <span>&lsquo;yes, <span>&ldquo;or?&rdquo;</span>&rsquo;</span>&rdquo;`,
			encoderMD:    "<q>say: <q>yes, <q>or?</q></q></q>",
			encoderSz:    `(INLINE (FORMAT-QUOTE () (TEXT "say:") (SPACE) (FORMAT-SPAN () (FORMAT-QUOTE () (TEXT "yes,") (SPACE) (FORMAT-SPAN () (FORMAT-QUOTE () (TEXT "or?")))))))`,
			encoderSHTML: `((@L (@H "&ldquo;") "say:" " " (span (@L (@H "&lsquo;") "yes," " " (span (@L (@H "&ldquo;") "or?" (@H "&rdquo;"))) (@H "&rsquo;"))) (@H "&rdquo;")))`,
			encoderText:  `say: yes, or?`,
			encoderZmk:   useZmk,
		},
	},
	{
		descr: "Two quotes",
		zmk:   `""yes"" or ""no""`,
		expect: expectMap{
			encoderHTML:  `&ldquo;yes&rdquo; or &ldquo;no&rdquo;`,
			encoderMD:    "<q>yes</q> or <q>no</q>",
			encoderSz:    `(INLINE (FORMAT-QUOTE () (TEXT "yes")) (SPACE) (TEXT "or") (SPACE) (FORMAT-QUOTE () (TEXT "no")))`,
			encoderSHTML: `((@L (@H "&ldquo;") "yes" (@H "&rdquo;")) " " "or" " " (@L (@H "&ldquo;") "no" (@H "&rdquo;")))`,
			encoderText:  `yes or no`,
			encoderZmk:   useZmk,
		},
	},
	{
		descr: "Mark formatting",
		zmk:   `##marked##`,
		expect: expectMap{
			encoderHTML:  `<mark>marked</mark>`,
			encoderMD:    "<mark>marked</mark>",
			encoderSz:    `(INLINE (FORMAT-MARK () (TEXT "marked")))`,
			encoderSHTML: `((mark "marked"))`,
			encoderText:  `marked`,
			encoderZmk:   useZmk,
		},
	},
	{
		descr: "Span formatting",
		zmk:   `::span::`,
		expect: expectMap{
			encoderHTML:  `<span>span</span>`,
			encoderMD:    "span",
			encoderSz:    `(INLINE (FORMAT-SPAN () (TEXT "span")))`,

			encoderZmk:   useZmk,
		},
	},
	{
		descr: "Nested Span Quote formatting",
		zmk:   `::""abc""::{lang=fr}`,
		expect: expectMap{
			encoderHTML:  `<span lang="fr">&laquo;&nbsp;abc&nbsp;&raquo;</span>`,
			encoderMD:    "<q>abc</q>",
			encoderSz:    `(INLINE (FORMAT-SPAN (quote (("lang" . "fr"))) (FORMAT-QUOTE () (TEXT "abc"))))`,
			encoderSHTML: `((span (@ (lang . "fr")) (@L (@H "&laquo;" "&nbsp;") "abc" (@H "&nbsp;" "&raquo;"))))`,
			encoderText:  `abc`,
			encoderZmk:   `::""abc""::{lang="fr"}`,
		},
	},
	{
		descr: "Simple Citation",
		zmk:   `[@Stern18]`,

		checkEncodings(t, testNum, pe, tc.descr, tc.expect, tc.zmk)
		checkSz(t, testNum, pe, tc.descr)
	}
}

func checkEncodings(t *testing.T, testNum int, pe parserEncoder, descr string, expected expectMap, zmkDefault string) {
	for enc, exp := range expected {
		encdr := encoder.Create(enc, &encoder.CreateParameter{Lang: api.ValueLangEN})
		got, err := pe.encode(encdr)
		if err != nil {
			prefix := fmt.Sprintf("Test #%d", testNum)
			if d := descr; d != "" {
				prefix += "\nReason:   " + d
			}
			prefix += "\nMode:     " + pe.mode()

			t.Errorf("%s\nEncoder:  %s\nExpected: %q\nGot:      %q", prefix, enc, exp, got)
		}
	}
}

func checkSz(t *testing.T, testNum int, pe parserEncoder, descr string) {
	t.Helper()
	encdr := encoder.Create(encoderSz, nil)
	exp, err := pe.encode(encdr)
	if err != nil {
		t.Error(err)
		return
	}
	val, err := sxreader.MakeReader(strings.NewReader(exp)).Read()
	if err != nil {

	"zettelstore.de/z/encoder/szenc"
	"zettelstore.de/z/encoder/textenc"
	"zettelstore.de/z/parser"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	encoder.Register(api.EncoderHTML, func(params *encoder.CreateParameter) encoder.Encoder { return Create(params) })
}

// Create an encoder.
func Create(params *encoder.CreateParameter) *Encoder {
	// We need a new transformer every time, because tx.inVerse must be unique.
	// If we can refactor it out, the transformer can be created only once.
	return &Encoder{
		tx:      szenc.NewTransformer(),
		th:      shtml.NewEvaluator(1, nil),
		lang:    params.Lang,
		textEnc: textenc.Create(),
	}
}

type Encoder struct {
	tx      *szenc.Transformer
	th      *shtml.Evaluator
	lang    string
	textEnc *textenc.Encoder
}

// WriteZettel encodes a full zettel as HTML5.
func (he *Encoder) WriteZettel(w io.Writer, zn *ast.ZettelNode, evalMeta encoder.EvalMetaFunc) (int, error) {
	env := shtml.MakeEnvironment(he.lang)
	hm, err := he.th.Evaluate(he.tx.GetMeta(zn.InhMeta, evalMeta), &env)
	if err != nil {
		return 0, err
	}

	var isTitle ast.InlineSlice
	var htitle *sx.Pair
	plainTitle, hasTitle := zn.InhMeta.Get(api.KeyTitle)
	if hasTitle {
		isTitle = parser.ParseSpacedText(plainTitle)
		xtitle := he.tx.GetSz(&isTitle)
		htitle, err = he.th.Evaluate(xtitle, &env)
		if err != nil {
			return 0, err
		}
	}

	xast := he.tx.GetSz(&zn.Ast)
	hast, err := he.th.Evaluate(xast, &env)
	if err != nil {
		return 0, err
	}
	hen := he.th.Endnotes(&env)

	sf := he.th.SymbolFactory()
	symAttr := sf.MustMake(sxhtml.NameSymAttr)

	head := sx.MakeList(sf.MustMake("head"))
	curr := head
	curr = curr.AppendBang(sx.Nil().Cons(sx.Nil().Cons(sx.Cons(sf.MustMake("charset"), sx.String("utf-8"))).Cons(symAttr)).Cons(sf.MustMake("meta")))
	for elem := hm; elem != nil; elem = elem.Tail() {
		curr = curr.AppendBang(elem.Car())
	}
	var sb strings.Builder
	if hasTitle {
		he.textEnc.WriteInlines(&sb, &isTitle)
	} else {
		sb.Write(zn.Meta.Zid.Bytes())
	}
	_ = curr.AppendBang(sx.Nil().Cons(sx.String(sb.String())).Cons(sf.MustMake("title")))

	body := sx.MakeList(sf.MustMake("body"))
	curr = body
	if hasTitle {
		curr = curr.AppendBang(htitle.Cons(sf.MustMake("h1")))
	}
	for elem := hast; elem != nil; elem = elem.Tail() {

	gen := sxhtml.NewGenerator(sf, sxhtml.WithNewline)
	return gen.WriteHTML(w, doc)
}

// WriteMeta encodes meta data as HTML5.
func (he *Encoder) WriteMeta(w io.Writer, m *meta.Meta, evalMeta encoder.EvalMetaFunc) (int, error) {
	env := shtml.MakeEnvironment(he.lang)
	hm, err := he.th.Evaluate(he.tx.GetMeta(m, evalMeta), &env)
	if err != nil {
		return 0, err
	}
	gen := sxhtml.NewGenerator(he.th.SymbolFactory(), sxhtml.WithNewline)
	return gen.WriteListHTML(w, hm)
}

func (he *Encoder) WriteContent(w io.Writer, zn *ast.ZettelNode) (int, error) {
	return he.WriteBlocks(w, &zn.Ast)
}

// WriteBlocks encodes a block slice.
func (he *Encoder) WriteBlocks(w io.Writer, bs *ast.BlockSlice) (int, error) {
	env := shtml.MakeEnvironment(he.lang)
	hobj, err := he.th.Evaluate(he.tx.GetSz(bs), &env)
	if err == nil {
		gen := sxhtml.NewGenerator(he.th.SymbolFactory())
		length, err2 := gen.WriteListHTML(w, hobj)
		if err2 != nil {
			return length, err2
		}

		l, err2 := gen.WriteHTML(w, he.th.Endnotes(&env))
		length += l
		return length, err2
	}
	return 0, err
}

// WriteInlines writes an inline slice to the writer
func (he *Encoder) WriteInlines(w io.Writer, is *ast.InlineSlice) (int, error) {
	env := shtml.MakeEnvironment(he.lang)
	hobj, err := he.th.Evaluate(he.tx.GetSz(is), &env)
	if err == nil {
		gen := sxhtml.NewGenerator(sx.FindSymbolFactory(hobj))
		length, err2 := gen.WriteListHTML(w, hobj)
		if err2 != nil {
			return length, err2
		}
		return length, nil
	}
	return 0, err
}

	"zettelstore.de/client.fossil/api"
	"zettelstore.de/z/ast"
	"zettelstore.de/z/encoder"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	encoder.Register(api.EncoderMD, func(*encoder.CreateParameter) encoder.Encoder { return Create() })
}

// Create an encoder.
func Create() *Encoder { return &myME }

type Encoder struct{}

		v.b.WriteString("__")
		ast.Walk(v, &fn.Inlines)
		v.b.WriteString("__")
	case ast.FormatQuote:
		v.b.WriteString("<q>")
		ast.Walk(v, &fn.Inlines)
		v.b.WriteString("</q>")
	case ast.FormatMark:
		v.b.WriteString("<mark>")
		ast.Walk(v, &fn.Inlines)
		v.b.WriteString("</mark>")
	default:
		ast.Walk(v, &fn.Inlines)
	}
}

func (v *visitor) visitLiteral(ln *ast.LiteralNode) {
	switch ln.Kind {

	"zettelstore.de/z/ast"
	"zettelstore.de/z/encoder"
	"zettelstore.de/z/encoder/szenc"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	encoder.Register(api.EncoderSHTML, func(params *encoder.CreateParameter) encoder.Encoder { return Create(params) })
}

// Create a SHTML encoder
func Create(params *encoder.CreateParameter) *Encoder {
	// We need a new transformer every time, because tx.inVerse must be unique.
	// If we can refactor it out, the transformer can be created only once.
	return &Encoder{
		tx:   szenc.NewTransformer(),
		th:   shtml.NewEvaluator(1, nil),
		lang: params.Lang,
	}
}

type Encoder struct {
	tx   *szenc.Transformer
	th   *shtml.Evaluator
	lang string
}

// WriteZettel writes the encoded zettel to the writer.
func (enc *Encoder) WriteZettel(w io.Writer, zn *ast.ZettelNode, evalMeta encoder.EvalMetaFunc) (int, error) {
	env := shtml.MakeEnvironment(enc.lang)
	metaSHTML, err := enc.th.Evaluate(enc.tx.GetMeta(zn.InhMeta, evalMeta), &env)
	if err != nil {
		return 0, err
	}
	contentSHTML, err := enc.th.Evaluate(enc.tx.GetSz(&zn.Ast), &env)
	if err != nil {
		return 0, err
	}
	result := sx.Cons(metaSHTML, contentSHTML)
	return result.Print(w)
}

// WriteMeta encodes meta data as s-expression.
func (enc *Encoder) WriteMeta(w io.Writer, m *meta.Meta, evalMeta encoder.EvalMetaFunc) (int, error) {
	env := shtml.MakeEnvironment(enc.lang)
	metaSHTML, err := enc.th.Evaluate(enc.tx.GetMeta(m, evalMeta), &env)
	if err != nil {
		return 0, err
	}
	return sx.Print(w, metaSHTML)
}

func (enc *Encoder) WriteContent(w io.Writer, zn *ast.ZettelNode) (int, error) {
	return enc.WriteBlocks(w, &zn.Ast)
}

// WriteBlocks writes a block slice to the writer
func (enc *Encoder) WriteBlocks(w io.Writer, bs *ast.BlockSlice) (int, error) {
	env := shtml.MakeEnvironment(enc.lang)
	hval, err := enc.th.Evaluate(enc.tx.GetSz(bs), &env)
	if err != nil {
		return 0, err
	}
	return sx.Print(w, hval)
}

// WriteInlines writes an inline slice to the writer
func (enc *Encoder) WriteInlines(w io.Writer, is *ast.InlineSlice) (int, error) {
	env := shtml.MakeEnvironment(enc.lang)
	hval, err := enc.th.Evaluate(enc.tx.GetSz(is), &env)
	if err != nil {
		return 0, err
	}
	return sx.Print(w, hval)
}

	"zettelstore.de/sx.fossil"
	"zettelstore.de/z/ast"
	"zettelstore.de/z/encoder"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	encoder.Register(api.EncoderSz, func(*encoder.CreateParameter) encoder.Encoder { return Create() })
}

// Create a S-expr encoder
func Create() *Encoder {
	// We need a new transformer every time, because trans.inVerse must be unique.
	// If we can refactor it out, the transformer can be created only once.
	return &Encoder{trans: NewTransformer()}

	"zettelstore.de/z/ast"
	"zettelstore.de/z/encoder"
	"zettelstore.de/z/zettel/meta"
)

// NewTransformer returns a new transformer to create s-expressions from AST nodes.
func NewTransformer() *Transformer {
	sf := sx.MakeMappedFactory(1024)
	t := Transformer{sf: sf}
	t.zetSyms.InitializeZettelSymbols(sf)

	t.mapVerbatimKindS = map[ast.VerbatimKind]*sx.Symbol{
		ast.VerbatimZettel:  t.zetSyms.SymVerbatimZettel,
		ast.VerbatimProg:    t.zetSyms.SymVerbatimProg,
		ast.VerbatimEval:    t.zetSyms.SymVerbatimEval,

		ast.FormatEmph:   t.zetSyms.SymFormatEmph,
		ast.FormatStrong: t.zetSyms.SymFormatStrong,
		ast.FormatDelete: t.zetSyms.SymFormatDelete,
		ast.FormatInsert: t.zetSyms.SymFormatInsert,
		ast.FormatSuper:  t.zetSyms.SymFormatSuper,
		ast.FormatSub:    t.zetSyms.SymFormatSub,
		ast.FormatQuote:  t.zetSyms.SymFormatQuote,
		ast.FormatMark:   t.zetSyms.SymFormatMark,
		ast.FormatSpan:   t.zetSyms.SymFormatSpan,
	}
	t.mapLiteralKindS = map[ast.LiteralKind]*sx.Symbol{
		ast.LiteralZettel:  t.zetSyms.SymLiteralZettel,
		ast.LiteralProg:    t.zetSyms.SymLiteralProg,
		ast.LiteralInput:   t.zetSyms.SymLiteralInput,
		ast.LiteralOutput:  t.zetSyms.SymLiteralOutput,

		return t.getInlineSlice(*n)
	case *ast.ParaNode:
		return t.getInlineSlice(n.Inlines).Tail().Cons(t.zetSyms.SymPara)
	case *ast.VerbatimNode:
		return sx.MakeList(
			mapGetS(t, t.mapVerbatimKindS, n.Kind),
			t.getAttributes(n.Attrs),
			sx.String(string(n.Content)),
		)
	case *ast.RegionNode:
		return t.getRegion(n)
	case *ast.HeadingNode:
		return sx.MakeList(
			t.zetSyms.SymHeading,
			sx.Int64(int64(n.Level)),
			t.getAttributes(n.Attrs),
			sx.String(n.Slug),
			sx.String(n.Fragment),
			t.getInlineSlice(n.Inlines),
		)
	case *ast.HRuleNode:
		return sx.MakeList(t.zetSyms.SymThematic, t.getAttributes(n.Attrs))
	case *ast.NestedListNode:
		return t.getNestedList(n)
	case *ast.DescriptionListNode:
		return t.getDescriptionList(n)
	case *ast.TableNode:
		return t.getTable(n)
	case *ast.TranscludeNode:
		return sx.MakeList(t.zetSyms.SymTransclude, t.getAttributes(n.Attrs), t.getReference(n.Ref))
	case *ast.BLOBNode:
		return t.getBLOB(n)
	case *ast.TextNode:
		return sx.MakeList(t.zetSyms.SymText, sx.String(n.Text))
	case *ast.SpaceNode:
		if t.inVerse {
			return sx.MakeList(t.zetSyms.SymSpace, sx.String(n.Lexeme))
		}
		return sx.MakeList(t.zetSyms.SymSpace)
	case *ast.BreakNode:
		if n.Hard {
			return sx.MakeList(t.zetSyms.SymHard)
		}
		return sx.MakeList(t.zetSyms.SymSoft)
	case *ast.LinkNode:
		return t.getLink(n)
	case *ast.EmbedRefNode:
		return t.getInlineSlice(n.Inlines).Tail().
			Cons(sx.String(n.Syntax)).
			Cons(t.getReference(n.Ref)).
			Cons(t.getAttributes(n.Attrs)).
			Cons(t.zetSyms.SymEmbed)
	case *ast.EmbedBLOBNode:
		return t.getEmbedBLOB(n)
	case *ast.CiteNode:
		return t.getInlineSlice(n.Inlines).Tail().
			Cons(sx.String(n.Key)).
			Cons(t.getAttributes(n.Attrs)).
			Cons(t.zetSyms.SymCite)
	case *ast.FootnoteNode:
		text := sx.Nil().Cons(sx.Nil().Cons(t.getInlineSlice(n.Inlines)).Cons(t.zetSyms.SymQuote))
		return text.Cons(t.getAttributes(n.Attrs)).Cons(t.zetSyms.SymEndnote)
	case *ast.MarkNode:
		return t.getInlineSlice(n.Inlines).Tail().
			Cons(sx.String(n.Fragment)).
			Cons(sx.String(n.Slug)).
			Cons(sx.String(n.Mark)).
			Cons(t.zetSyms.SymMark)
	case *ast.FormatNode:
		return t.getInlineSlice(n.Inlines).Tail().
			Cons(t.getAttributes(n.Attrs)).
			Cons(mapGetS(t, t.mapFormatKindS, n.Kind))
	case *ast.LiteralNode:
		return sx.MakeList(
			mapGetS(t, t.mapLiteralKindS, n.Kind),
			t.getAttributes(n.Attrs),
			sx.String(string(n.Content)),
		)
	}
	return sx.MakeList(t.zetSyms.SymUnknown, sx.String(fmt.Sprintf("%T %v", node, node)))
}

func (t *Transformer) getRegion(rn *ast.RegionNode) *sx.Pair {
	saveInVerse := t.inVerse
	if rn.Kind == ast.RegionVerse {
		t.inVerse = true
	}

func (t *Transformer) getCell(cell *ast.TableCell) *sx.Pair {
	return t.getInlineSlice(cell.Inlines).Tail().Cons(mapGetS(t, t.alignmentSymbolS, cell.Align))
}

func (t *Transformer) getBLOB(bn *ast.BLOBNode) *sx.Pair {
	var lastObj sx.Object
	if bn.Syntax == meta.SyntaxSVG {
		lastObj = sx.String(string(bn.Blob))
	} else {
		lastObj = getBase64String(bn.Blob)
	}
	return sx.MakeList(
		t.zetSyms.SymBLOB,
		t.getInlineSlice(bn.Description),
		sx.String(bn.Syntax),
		lastObj,
	)
}

func (t *Transformer) getLink(ln *ast.LinkNode) *sx.Pair {
	return t.getInlineSlice(ln.Inlines).Tail().
		Cons(sx.String(ln.Ref.Value)).
		Cons(t.getAttributes(ln.Attrs)).
		Cons(mapGetS(t, t.mapRefStateLink, ln.Ref.State))
}

func (t *Transformer) getEmbedBLOB(en *ast.EmbedBLOBNode) *sx.Pair {
	tail := t.getInlineSlice(en.Inlines).Tail()
	if en.Syntax == meta.SyntaxSVG {
		tail = tail.Cons(sx.String(string(en.Blob)))
	} else {
		tail = tail.Cons(getBase64String(en.Blob))
	}
	return tail.Cons(sx.String(en.Syntax)).Cons(t.getAttributes(en.Attrs)).Cons(t.zetSyms.SymEmbedBLOB)
}

func (t *Transformer) getBlockSlice(bs *ast.BlockSlice) *sx.Pair {
	objs := make([]sx.Object, len(*bs))
	for i, n := range *bs {
		objs[i] = t.GetSz(n)
	}

func (t *Transformer) getAttributes(a attrs.Attributes) sx.Object {
	if a.IsEmpty() {
		return sx.Nil()
	}
	keys := a.Keys()
	objs := make([]sx.Object, 0, len(keys))
	for _, k := range keys {
		objs = append(objs, sx.Cons(sx.String(k), sx.String(a[k])))
	}
	return sx.Nil().Cons(sx.MakeList(objs...)).Cons(t.zetSyms.SymQuote)
}

func (t *Transformer) getReference(ref *ast.Reference) *sx.Pair {
	return sx.MakeList(
		t.zetSyms.SymQuote,
		sx.MakeList(
			mapGetS(t, t.mapRefStateS, ref.State),
			sx.String(ref.Value),
		),
	)
}

func (t *Transformer) GetMeta(m *meta.Meta, evalMeta encoder.EvalMetaFunc) *sx.Pair {
	pairs := m.ComputedPairs()
	objs := make([]sx.Object, 0, len(pairs))
	for _, p := range pairs {
		key := p.Key
		ty := m.Type(key)
		symType := mapGetS(t, t.mapMetaTypeS, ty)
		var obj sx.Object
		if ty.IsSet {
			setList := meta.ListFromValue(p.Value)
			setObjs := make([]sx.Object, len(setList))
			for i, val := range setList {
				setObjs[i] = sx.String(val)
			}
			obj = sx.MakeList(setObjs...).Cons(t.zetSyms.SymList)
		} else if ty == meta.TypeZettelmarkup {
			is := evalMeta(p.Value)
			obj = t.GetSz(&is)
		} else {
			obj = sx.String(p.Value)
		}
		symKey := sx.MakeList(t.zetSyms.SymQuote, t.sf.MustMake(key))
		objs = append(objs, sx.Nil().Cons(obj).Cons(symKey).Cons(symType))
	}
	return sx.MakeList(objs...).Cons(t.zetSyms.SymMeta)
}

	var sb strings.Builder
	encoder := base64.NewEncoder(base64.StdEncoding, &sb)
	_, err := encoder.Write(data)
	if err == nil {
		err = encoder.Close()
	}
	if err == nil {
		return sx.String(sb.String())
	}
	return sx.String("")
}

	"zettelstore.de/client.fossil/api"
	"zettelstore.de/z/ast"
	"zettelstore.de/z/encoder"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	encoder.Register(api.EncoderText, func(*encoder.CreateParameter) encoder.Encoder { return Create() })
}

// Create an encoder.
func Create() *Encoder { return &myTE }

type Encoder struct{}

	"zettelstore.de/z/encoder"
	"zettelstore.de/z/encoder/textenc"
	"zettelstore.de/z/strfun"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	encoder.Register(api.EncoderZmk, func(*encoder.CreateParameter) encoder.Encoder { return Create() })
}

// Create an encoder.
func Create() *Encoder { return &myZE }

type Encoder struct{}

	}
	var sb strings.Builder
	v.textEnc.WriteInlines(&sb, &bn.Description)
	v.b.WriteStrings("%% Unable to display BLOB with description '", sb.String(), "' and syntax '", bn.Syntax, "'.")
}

var escapeSeqs = strfun.NewSet(
	"\\", "__", "**", "~~", "^^", ",,", ">>", `""`, "::", "''", "``", "++", "==", "##",
)

func (v *visitor) visitText(tn *ast.TextNode) {
	last := 0
	for i := 0; i < len(tn.Text); i++ {
		if b := tn.Text[i]; b == '\\' {
			v.b.WriteString(tn.Text[last:i])

	ast.FormatEmph:   []byte("__"),
	ast.FormatStrong: []byte("**"),
	ast.FormatInsert: []byte(">>"),
	ast.FormatDelete: []byte("~~"),
	ast.FormatSuper:  []byte("^^"),
	ast.FormatSub:    []byte(",,"),
	ast.FormatQuote:  []byte(`""`),
	ast.FormatMark:   []byte("##"),
	ast.FormatSpan:   []byte("::"),
}

func (v *visitor) visitFormat(fn *ast.FormatNode) {
	kind, ok := mapFormatKind[fn.Kind]
	if !ok {
		panic(fmt.Sprintf("Unknown format kind %d", fn.Kind))

	buf.WriteString("</feed>")
	return buf.Bytes()
}

func (c *Configuration) marshalMeta(buf *bytes.Buffer, m *meta.Meta) {
	entryUpdated := ""
	if val, found := m.Get(api.KeyPublished); found {
		if published, err := time.ParseInLocation(id.TimestampLayout, val, time.Local); err == nil {
			entryUpdated = published.UTC().Format(time.RFC3339)
		}
	}

	link := c.NewURLBuilderAbs().SetZid(api.ZettelID(m.Zid.String())).String()

	buf.WriteString("  <entry>\n")

)

// LastUpdated returns the formated time of the zettel which was updated at the latest time.
func LastUpdated(ml []*meta.Meta, timeFormat string) string {
	maxPublished := time.Date(1, time.January, 1, 0, 0, 0, 0, time.Local)
	for _, m := range ml {
		if val, found := m.Get(api.KeyPublished); found {
			if published, err := time.ParseInLocation(id.TimestampLayout, val, time.Local); err == nil {
				if maxPublished.Before(published) {
					maxPublished = published
				}
			}
		}
	}
	if maxPublished.Year() > 1 {

	buf.WriteString("</channel>\n</rss>")
	return buf.Bytes()
}

func (c *Configuration) marshalMeta(buf *bytes.Buffer, m *meta.Meta) {
	itemPublished := ""
	if val, found := m.Get(api.KeyPublished); found {
		if published, err := time.ParseInLocation(id.TimestampLayout, val, time.Local); err == nil {
			itemPublished = published.UTC().Format(time.RFC1123Z)
		}
	}

	link := c.NewURLBuilderAbs().SetZid(api.ZettelID(m.Zid.String())).String()

	buf.WriteString("  <item>\n")

				ap.max = num
				continue
			}
		}
		if act == "TITLE" && i+1 < len(actions) {
			ap.title = strings.Join(actions[i+1:], " ")
			break
		}
		if act == "REINDEX" {
			continue
		}
		acts = append(acts, act)
	}
	var firstUnknownKey string
	for _, act := range acts {
		switch act {
		case "ATOM":

		sliceData = meta.ListFromValue(value)
		if len(sliceData) == 0 {
			return nil
		}
	} else {
		sliceData = []string{value}
	}



	makeLink := dt == meta.TypeID || dt == meta.TypeIDSet


	result := make(ast.InlineSlice, 0, 2*len(sliceData)-1)
	for i, val := range sliceData {
		if i > 0 {
			result = append(result, &ast.SpaceNode{Lexeme: " "})
		}
		tn := &ast.TextNode{Text: val}

module zettelstore.de/z

go 1.21

require (
	github.com/fsnotify/fsnotify v1.7.0
	github.com/yuin/goldmark v1.6.0
	golang.org/x/crypto v0.16.0
	golang.org/x/term v0.15.0
	golang.org/x/text v0.14.0
	zettelstore.de/client.fossil v0.0.0-20231130151508-751754d40c73
	zettelstore.de/sx.fossil v0.0.0-20231130150648-05ef116ba207
)

require golang.org/x/sys v0.15.0 // indirect

github.com/fsnotify/fsnotify v1.7.0 h1:8JEhPFa5W2WU7YfeZzPNqzMP6Lwt7L2715Ggo0nosvA=
github.com/fsnotify/fsnotify v1.7.0/go.mod h1:40Bi/Hjc2AVfZrqy+aj+yEI+/bRxZnMJyTJwOpGvigM=
github.com/yuin/goldmark v1.6.0 h1:boZcn2GTjpsynOsC0iJHnBWa4Bi0qzfJjthwauItG68=
github.com/yuin/goldmark v1.6.0/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
golang.org/x/crypto v0.16.0 h1:mMMrFzRSCF0GvB7Ne27XVtVAaXLrPmgPC7/v0tkwHaY=
golang.org/x/crypto v0.16.0/go.mod h1:gCAAfMLgwOJRpTjQ2zCCt2OcSfYMTeZVSRtQlPC7Nq4=

golang.org/x/sys v0.15.0 h1:h48lPFYpsTvQJZF4EKyI4aLHaev3CxivZmv7yZig9pc=
golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
golang.org/x/term v0.15.0 h1:y/Oo/a/q3IXu26lQgl04j/gjuBDOBlx7X6Om1j2CPW4=
golang.org/x/term v0.15.0/go.mod h1:BDl952bC7+uMoWR75FIrCDx79TPU9oHkTZ9yRbYOrX0=
golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
zettelstore.de/client.fossil v0.0.0-20231130151508-751754d40c73 h1:LPF8QWip3GRLBzgPdnsJnrvk1sGiMOSpqOwURiax9gg=
zettelstore.de/client.fossil v0.0.0-20231130151508-751754d40c73/go.mod h1:fN+1WxRorSbHduS0T0B4GI8o82EgFuUWBv6fwsAZF6o=
zettelstore.de/sx.fossil v0.0.0-20231130150648-05ef116ba207 h1:8ch54z0w53bps6a00NDofEqo3AJ1l7ITXyC3XyLmlY4=
zettelstore.de/sx.fossil v0.0.0-20231130150648-05ef116ba207/go.mod h1:Uw3OLM1ufOM4Xe0G51mvkTDUv2okd+HyDBMx+0ZG7ME=

	"zettelstore.de/z/zettel/meta"
)

type configService struct {
	srvConfig
	mxService sync.RWMutex
	orig      *meta.Meta
	manager   box.Manager
}

// Predefined Metadata keys for runtime configuration
// See: https://zettelstore.de/manual/h/00001004020000
const (
	keyDefaultCopyright  = "default-copyright"
	keyDefaultLicense    = "default-license"

		keySiteName:         {"Site name", parseString, true},
		keyYAMLHeader:       {"YAML header", parseBool, true},
		keyZettelFileSyntax: {
			"Zettel file syntax",
			func(val string) (any, error) { return strings.Fields(val), nil },
			true,
		},
		kernel.ConfigSimpleMode:        {"Simple mode", cs.noFrozen(parseBool), true},
		config.KeyShowBackLinks:        {"Show back links", parseString, true},
		config.KeyShowFolgeLinks:       {"Show folge links", parseString, true},
		config.KeyShowSubordinateLinks: {"Show subordinate links", parseString, true},
		config.KeyShowSuccessorLinks:   {"Show successor links", parseString, true},
	}
	cs.next = interfaceMap{
		keyDefaultCopyright:            "",
		keyDefaultLicense:              "",
		keyDefaultVisibility:           meta.VisibilityLogin,
		keyExpertMode:                  false,
		config.KeyFooterZettel:         id.Invalid,
		config.KeyHomeZettel:           id.DefaultHomeZid,
		kernel.ConfigInsecureHTML:      config.NoHTML,
		api.KeyLang:                    api.ValueLangEN,
		keyMaxTransclusions:            int64(1024),
		keySiteName:                    "Zettelstore",
		keyYAMLHeader:                  false,
		keyZettelFileSyntax:            nil,
		kernel.ConfigSimpleMode:        false,
		config.KeyShowBackLinks:        "",
		config.KeyShowFolgeLinks:       "",
		config.KeyShowSubordinateLinks: "",
		config.KeyShowSuccessorLinks:   "",
	}
}
func (cs *configService) GetLogger() *logger.Logger { return cs.logger }

func (cs *configService) Start(*myKernel) error {
	cs.logger.Info().Msg("Start Service")
	data := meta.New(id.ConfigurationZid)

	return cs.orig != nil
}

func (cs *configService) Stop(*myKernel) {
	cs.logger.Info().Msg("Stop Service")
	cs.mxService.Lock()
	cs.orig = nil
	cs.manager = nil
	cs.mxService.Unlock()
}

func (*configService) GetStatistics() []kernel.KeyValue {
	return nil
}

func (cs *configService) setBox(mgr box.Manager) {
	cs.mxService.Lock()
	cs.manager = mgr
	cs.mxService.Unlock()
	mgr.RegisterObserver(cs.observe)
	cs.observe(box.UpdateInfo{Box: mgr, Reason: box.OnZettel, Zid: id.ConfigurationZid})
}

func (cs *configService) doUpdate(p box.BaseBox) error {
	z, err := p.GetZettel(context.Background(), id.ConfigurationZid)
	cs.logger.Trace().Err(err).Msg("got config meta")
	if err != nil {
		return err
	}
	m := z.Meta
	cs.mxService.Lock()
	for _, pair := range cs.orig.Pairs() {

	cs.SwitchNextToCur() // Poor man's restart
	return nil
}

func (cs *configService) observe(ci box.UpdateInfo) {
	if ci.Reason != box.OnZettel || ci.Zid == id.ConfigurationZid {
		cs.logger.Debug().Uint("reason", uint64(ci.Reason)).Zid(ci.Zid).Msg("observe")
		go func() {
			cs.mxService.RLock()
			mgr := cs.manager
			cs.mxService.RUnlock()
			if mgr != nil {
				cs.doUpdate(mgr)
			} else {
				cs.doUpdate(ci.Box)
			}
		}()
	}
}

// --- config.Config

func (cs *configService) Get(ctx context.Context, m *meta.Meta, key string) string {
	if m != nil {

	cs.next = interfaceMap{
		kernel.CoreDebug:     false,
		kernel.CoreGoArch:    runtime.GOARCH,
		kernel.CoreGoOS:      runtime.GOOS,
		kernel.CoreGoVersion: runtime.Version(),
		kernel.CoreHostname:  "*unknown host*",
		kernel.CorePort:      0,
		kernel.CoreStarted:   time.Now().Local().Format(id.TimestampLayout),
		kernel.CoreVerbose:   false,
	}
	if hn, err := os.Hostname(); err == nil {
		cs.next[kernel.CoreHostname] = hn
	}
}

	}
	return kern
}

func (kern *myKernel) Setup(progname, version string, versionTime time.Time) {
	kern.SetConfig(kernel.CoreService, kernel.CoreProgname, progname)
	kern.SetConfig(kernel.CoreService, kernel.CoreVersion, version)
	kern.SetConfig(kernel.CoreService, kernel.CoreVTime, versionTime.Local().Format(id.TimestampLayout))
}

func (kern *myKernel) Start(headline, lineServer bool, configFilename string) {
	for _, srvD := range kern.srvs {
		srvD.srv.Freeze()
	}
	if kern.cfg.GetCurConfig(kernel.ConfigSimpleMode).(bool) {

	go func() { lineServer(ln, kern) }()
	return nil
}

func lineServer(ln net.Listener, kern *myKernel) {
	// Something may panic. Ensure a running line service.
	defer func() {
		if ri := recover(); ri != nil {
			kern.doLogRecover("Line", ri)
			go lineServer(ln, kern)
		}
	}()

	for {
		conn, err := ln.Accept()
		if err != nil {
			// handle error
			kern.logger.Error().Err(err).Msg("Unable to accept connection")
			break
		}
		go handleLineConnection(conn, kern)
	}
	ln.Close()
}

func handleLineConnection(conn net.Conn, kern *myKernel) {
	// Something may panic. Ensure a running connection.
	defer func() {
		if ri := recover(); ri != nil {
			kern.doLogRecover("LineConn", ri)
			go handleLineConnection(conn, kern)
		}
	}()

	kern.logger.Mandatory().Str("from", conn.RemoteAddr().String()).Msg("Start session on administration console")
	cmds := cmdSession{}
	cmds.initialize(conn, kern)

// Warn creates a message suitable for warning the user.
func (l *Logger) Warn() *Message { return newMessage(l, WarnLevel) }

// Error creates a message suitable for errors.
func (l *Logger) Error() *Message { return newMessage(l, ErrorLevel) }









// Fatal creates a message suitable for fatal errors.
func (l *Logger) Fatal() *Message { return newMessage(l, FatalLevel) }

// Panic creates a message suitable for panicing.
func (l *Logger) Panic() *Message { return newMessage(l, PanicLevel) }

// Mandatory creates a message that will always logged, except when logging

	return ast.CreateInlineSliceFromWords(meta.ListFromValue(s)...)
}

// NormalizedSpacedText returns the given string, but normalize multiple spaces to one space.
func NormalizedSpacedText(s string) string { return strings.Join(meta.ListFromValue(s), " ") }

// ParseDescription returns a suitable description stored in the metadata as an inline slice.
// This is done for an image in most cases.
func ParseDescription(m *meta.Meta) ast.InlineSlice {
	if m == nil {
		return nil
	}
	if descr, found := m.Get(api.KeySummary); found {
		in := ParseMetadata(descr)
		cleaner.CleanInlineLinks(&in)
		return in
	}
	if title, found := m.Get(api.KeyTitle); found {
		return ParseSpacedText(title)
	}
	return ast.CreateInlineSliceFromWords("Zettel", "without", "title:", m.Zid.String())
}

// ParseZettel parses the zettel based on the syntax.
func ParseZettel(ctx context.Context, zettel zettel.Zettel, syntax string, rtConfig config.Config) *ast.ZettelNode {
	m := zettel.Meta
	inhMeta := m
	if rtConfig != nil {

package plain

import (
	"bytes"
	"strings"

	"zettelstore.de/client.fossil/attrs"
	"zettelstore.de/sx.fossil/sxbuiltins"

	"zettelstore.de/sx.fossil/sxreader"
	"zettelstore.de/z/ast"
	"zettelstore.de/z/input"
	"zettelstore.de/z/parser"
	"zettelstore.de/z/zettel/meta"
)

	}
	// TODO: check proper end </svg>
	return svgSrc
}

func parseSxnBlocks(inp *input.Input, _ *meta.Meta, syntax string) ast.BlockSlice {
	rd := sxreader.MakeReader(bytes.NewReader(inp.Src))






	objs, err := rd.ReadAll()
	if err != nil {
		return ast.BlockSlice{
			&ast.VerbatimNode{
				Kind:    ast.VerbatimProg,
				Attrs:   attrs.Attributes{"": syntax},
				Content: inp.ScanLineContent(),
			},
			ast.CreateParaNode(&ast.TextNode{
				Text: err.Error(),
			}),
		}
	}
	result := make(ast.BlockSlice, len(objs))
	for i, obj := range objs {
		var buf bytes.Buffer
		sxbuiltins.Print(&buf, obj)
		result[i] = &ast.VerbatimNode{
			Kind:    ast.VerbatimProg,
			Attrs:   attrs.Attributes{"": syntax},
			Content: buf.Bytes(),
		}
	}
	return result

		case '{':
			inp.Next()
			if inp.Ch == '{' {
				in, success = cp.parseEmbed()
			}
		case '%':
			in, success = cp.parseComment()
		case '_', '*', '>', '~', '^', ',', '"', '#', ':':
			in, success = cp.parseFormat()
		case '@', '\'', '`', '=', runeModGrave:
			in, success = cp.parseLiteral()
		case '$':
			in, success = cp.parseLiteralMath()
		case '\\':
			return cp.parseBackslash()

		return cp.parseBackslashRest()
	}
	for {
		inp.Next()
		switch inp.Ch {
		// The following case must contain all runes that occur in parseInline!
		// Plus the closing brackets ] and } and ) and the middle |
		case input.EOS, '\n', '\r', ' ', '\t', '[', ']', '{', '}', '(', ')', '|', '%', '_', '*', '>', '~', '^', ',', '"', '#', ':', '\'', '@', '`', runeModGrave, '$', '=', '\\', '-', '&':
			return &ast.TextNode{Text: string(inp.Src[pos:inp.Pos])}
		}
	}
}

func (cp *zmkP) parseBackslash() ast.InlineNode {
	inp := cp.inp

	'_': ast.FormatEmph,
	'*': ast.FormatStrong,
	'>': ast.FormatInsert,
	'~': ast.FormatDelete,
	'^': ast.FormatSuper,
	',': ast.FormatSub,
	'"': ast.FormatQuote,
	'#': ast.FormatMark,
	':': ast.FormatSpan,
}

func (cp *zmkP) parseFormat() (res ast.InlineNode, success bool) {
	inp := cp.inp
	fch := inp.Ch
	kind, ok := mapRuneFormat[fch]

		{"100%", "(PARA 100%)"},
	})
}

func TestFormat(t *testing.T) {
	t.Parallel()
	// Not for Insert / '>', because collision with quoted list
	for _, ch := range []string{"_", "*", "~", "^", ",", "\"", "#", ":"} {
		checkTcs(t, replace(ch, TestCases{
			{"$", "(PARA $)"},
			{"$$", "(PARA $$)"},
			{"$$$", "(PARA $$$)"},
			{"$$$$", "(PARA {$})"},
		}))
	}
	for _, ch := range []string{"_", "*", ">", "~", "^", ",", "\"", "#", ":"} {
		checkTcs(t, replace(ch, TestCases{
			{"$$a$$", "(PARA {$ a})"},
			{"$$a$$$", "(PARA {$ a} $)"},
			{"$$$a$$", "(PARA {$ $a})"},
			{"$$$a$$$", "(PARA {$ $a} $)"},
			{"$\\$", "(PARA $$)"},
			{"$\\$$", "(PARA $$$)"},

	ast.FormatEmph:   '_',
	ast.FormatStrong: '*',
	ast.FormatInsert: '>',
	ast.FormatDelete: '~',
	ast.FormatSuper:  '^',
	ast.FormatSub:    ',',
	ast.FormatQuote:  '"',
	ast.FormatMark:   '#',
	ast.FormatSpan:   ':',
}

var mapLiteralKind = map[ast.LiteralKind]rune{
	ast.LiteralZettel:  '@',
	ast.LiteralProg:    '`',
	ast.LiteralInput:   '\'',

type CompiledTerm struct {
	Match    MetaMatchFunc     // Match on metadata
	Retrieve RetrievePredicate // Retrieve from full-text search
}

// RetrievePredicate returns true, if the given Zid is contained in the (full-text) search.
type RetrievePredicate func(id.Zid) bool

// AlwaysIncluded is a RetrievePredicate that always returns true.
func AlwaysIncluded(id.Zid) bool { return true }
func neverIncluded(id.Zid) bool  { return false }

func (c *Compiled) isDeterministic() bool { return c.seed > 0 }

// Result returns a result of the compiled search, that is achievable without iterating through a box.
func (c *Compiled) Result() []*meta.Meta {
	if len(c.startMeta) == 0 {
		// nil -> no directive

//-----------------------------------------------------------------------------
// Copyright (c) 2023-present Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package query

import (
	"container/heap"
	"context"

	"zettelstore.de/client.fossil/api"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

				tasks.addSameTag(ctx, tag, cost)
			}
		}
	}
	return result
}

type ztlCtxItem struct {
	cost int

	meta *meta.Meta
}
type ztlCtxQueue []ztlCtxItem

func (q ztlCtxQueue) Len() int           { return len(q) }
func (q ztlCtxQueue) Less(i, j int) bool { return q[i].cost < q[j].cost }
func (q ztlCtxQueue) Swap(i, j int)      { q[i], q[j] = q[j], q[i] }
func (q *ztlCtxQueue) Push(x any)        { *q = append(*q, x.(ztlCtxItem)) }
func (q *ztlCtxQueue) Pop() any {
	old := *q
	n := len(old)
	item := old[n-1]
	old[n-1].meta = nil // avoid memory leak
	*q = old[0 : n-1]
	return item
}

type contextTask struct {
	port    ContextPort
	seen    id.Set
	queue   ztlCtxQueue

	maxCost int
	limit   int
	tagCost map[string][]*meta.Meta
}

func newQueue(startSeq []*meta.Meta, maxCost, limit int, port ContextPort) *contextTask {
	result := &contextTask{
		port:    port,
		seen:    id.NewSet(),


		maxCost: maxCost,
		limit:   limit,
		tagCost: make(map[string][]*meta.Meta, 1024),
	}

	queue := make(ztlCtxQueue, 0, len(startSeq))
	for _, m := range startSeq {
		queue = append(queue, ztlCtxItem{cost: 1, meta: m})




	}
	heap.Init(&queue)
	result.queue = queue


	return result
}

func (ct *contextTask) addPair(ctx context.Context, key, value string, curCost int, isBackward, isForward bool) {
	if key == api.KeyBack {
		return
	}
	newCost := curCost + contextCost(key)
	if key == api.KeyBackward {
		if isBackward {
			ct.addIDSet(ctx, newCost, value)
		}
		return
	}
	if key == api.KeyForward {
		if isForward {
			ct.addIDSet(ctx, newCost, value)
		}
		return
	}
	hasInverse := meta.Inverse(key) != ""
	if (!hasInverse || !isBackward) && (hasInverse || !isForward) {
		return
	}
	if t := meta.Type(key); t == meta.TypeID {
		ct.addID(ctx, newCost, value)
	} else if t == meta.TypeIDSet {
		ct.addIDSet(ctx, newCost, value)
	}
}

func contextCost(key string) int {
	switch key {
	case api.KeyFolge, api.KeyPrecursor:
		return 1
	case api.KeySuccessors, api.KeyPredecessor,
		api.KeySubordinates, api.KeySuperior:
		return 2
	}
	return 3
}

func (ct *contextTask) addID(ctx context.Context, newCost int, value string) {
	if ct.costMaxed(newCost) {
		return
	}
	if zid, errParse := id.Parse(value); errParse == nil {
		if m, errGetMeta := ct.port.GetMeta(ctx, zid); errGetMeta == nil {
			ct.addMeta(m, newCost)
		}
	}
}
func (ct *contextTask) addMeta(m *meta.Meta, newCost int) {
	if _, found := ct.seen[m.Zid]; !found {
		heap.Push(&ct.queue, ztlCtxItem{cost: newCost, meta: m})




	}
}























func (ct *contextTask) costMaxed(newCost int) bool {
	// If len(zc.seen) <= 1, the initial zettel is processed. In this case allow all
	// other zettel that are directly reachable, without taking the cost into account.
	// Of course, the limit ist still relevant.
	return (len(ct.seen) > 1 && ct.maxCost > 0 && newCost > ct.maxCost) || ct.hasLimit()
}

func (ct *contextTask) addIDSet(ctx context.Context, newCost int, value string) {
	elems := meta.ListFromValue(value)
	refCost := referenceCost(newCost, len(elems))
	for _, val := range elems {
		ct.addID(ctx, refCost, val)
	}
}

func referenceCost(baseCost int, numReferences int) int {
	switch {
	case numReferences < 5:
		return baseCost + 1

	case numReferences < 9:
		return baseCost * 2

	case numReferences < 17:
		return baseCost * 3

	case numReferences < 33:
		return baseCost * 4

	case numReferences < 65:
		return baseCost * 5
	}
	return baseCost * numReferences / 8
}

func (ct *contextTask) addSameTag(ctx context.Context, tag string, baseCost int) {
	tagMetas, found := ct.tagCost[tag]
	if !found {
		q := Parse(api.KeyTags + api.SearchOperatorHas + tag + " ORDER REVERSE " + api.KeyID)
		ml, err := ct.port.SelectMeta(ctx, nil, q)
		if err != nil {
			return
		}
		tagMetas = ml
		ct.tagCost[tag] = ml
	}
	cost := tagCost(baseCost, len(tagMetas))
	if ct.costMaxed(cost) {
		return
	}
	for _, m := range tagMetas {
		ct.addMeta(m, cost)
	}
}

func tagCost(baseCost, numTags int) int {
	if numTags < 8 {
		return baseCost + numTags/2
	}
	return (baseCost + 2) * (numTags / 4)
}

func (ct *contextTask) next() (*meta.Meta, int) {
	if ct.hasLimit() {
		return nil, -1
	}
	for len(ct.queue) > 0 {
		item := heap.Pop(&ct.queue).(ztlCtxItem)






		m := item.meta
		zid := m.Zid
		if _, found := ct.seen[zid]; found {

			continue
		}
		ct.seen.Add(zid)
		return m, item.cost
	}
	return nil, -1
}

func (ct *contextTask) hasLimit() bool {
	limit := ct.limit
	return limit > 0 && len(ct.seen) >= limit
}

type parserState struct {
	inp *input.Input
}

func (ps *parserState) mustStop() bool { return ps.inp.Ch == input.EOS }
func (ps *parserState) acceptSingleKw(s string) bool {
	if ps.inp.Accept(s) && (ps.isSpace() || ps.isActionSep() || ps.mustStop()) {
		return true
	}
	return false
}
func (ps *parserState) acceptKwArgs(s string) bool {
	if ps.inp.Accept(s) && ps.isSpace() {
		ps.skipSpace()

	for {
		pos := inp.Pos
		zid, found := ps.scanZid()
		if !found {
			inp.SetPos(pos)
			break
		}
		if !zidSet.ContainsOrNil(zid) {
			zidSet.Add(zid)
			q = createIfNeeded(q)
			q.zids = append(q.zids, zid)
		}
		ps.skipSpace()
		if ps.mustStop() {
			q.zids = nil
			break

		}
		pos := inp.Pos
		if ps.acceptSingleKw(api.ContextDirective) {
			if hasContext {
				inp.SetPos(pos)
				break
			}
			q = ps.parseContext(q)
			hasContext = true
			continue
		}
		inp.SetPos(pos)
		if q == nil || len(q.zids) == 0 {
			break
		}