Zettelstore

often connects to Zettelstore via its API. Some of the software packages may be
experimental.

The software, including the manual, is licensed
under the [European Union Public License 1.2 (or
later)](https://zettelstore.de/home/file?name=LICENSE.txt&ci=trunk).

[Stay](https://twitter.com/zettelstore)
[Stay tuned](https://twitter.com/search?q=%40t73fde%20zettelstore&f=live) …
<a rel="me" href="https://nerdculture.de/@zettelstore">tuned</a>&nbsp;&hellip;

0.11.0
0.12-dev

// Package ast provides the abstract syntax tree for parsed zettel content.
package ast

import (
	"net/url"

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

// ZettelNode is the root node of the abstract syntax tree.
// It is *not* part of the visitor pattern.
type ZettelNode struct {
	Meta    *meta.Meta     // Original metadata
	Content domain.Content // Original content
	Content zettel.Content // Original content
	Zid     id.Zid         // Zettel identification.
	InhMeta *meta.Meta     // Metadata of the zettel, with inherited values.
	Ast     BlockSlice     // Zettel abstract syntax tree is a sequence of block nodes.
	Syntax  string         // Syntax / parser that produced the Ast
}

// Node is the interface, all nodes must implement.

package ast

import (
	"net/url"
	"strings"

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

// QueryPrefix is the prefix that denotes a query expression.
const QueryPrefix = "query:"

// ParseReference parses a string and returns a reference.
func ParseReference(s string) *Reference {

package auth

import (
	"time"

	"zettelstore.de/z/box"
	"zettelstore.de/z/config"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

// BaseManager allows to check some base auth modes.
type BaseManager interface {
	// IsReadonly returns true, if the systems is configured to run in read-only-mode.
	IsReadonly() bool
}

// TokenKind specifies for which application / usage a token is/was requested.
type TokenKind int

// Allowed values of token kind
const (
	_ TokenKind = iota
	KindJSON
	KindHTML
	KindAPI
	KindwebUI
)

// TokenData contains some important elements from a token.
type TokenData struct {
	Token   []byte
	Now     time.Time
	Issued  time.Time

// Package cred provides some function for handling credentials.
package cred

import (
	"bytes"

	"golang.org/x/crypto/bcrypt"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/zettel/id"
)

// HashCredential returns a hashed vesion of the given credential
func HashCredential(zid id.Zid, ident, credential string) (string, error) {
	fullCredential := createFullCredential(zid, ident, credential)
	res, err := bcrypt.GenerateFromPassword(fullCredential, bcrypt.DefaultCost)
	if err != nil {

	"github.com/pascaldekloe/jwt"

	"zettelstore.de/c/api"
	"zettelstore.de/z/auth"
	"zettelstore.de/z/auth/policy"
	"zettelstore.de/z/box"
	"zettelstore.de/z/config"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

type myAuth struct {
	readonly bool
	owner    id.Zid
	secret   []byte
}

//-----------------------------------------------------------------------------

package policy

import (
	"zettelstore.de/z/auth"
	"zettelstore.de/z/config"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/zettel/meta"
)

type anonPolicy struct {
	authConfig config.AuthConfig
	pre        auth.Policy
}

import (
	"context"

	"zettelstore.de/z/auth"
	"zettelstore.de/z/box"
	"zettelstore.de/z/config"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/query"
	"zettelstore.de/z/web/server"
	"zettelstore.de/z/query"
	"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,

	return pp.box.Location()
}

func (pp *polBox) CanCreateZettel(ctx context.Context) bool {
	return pp.box.CanCreateZettel(ctx)
}

func (pp *polBox) CreateZettel(ctx context.Context, zettel domain.Zettel) (id.Zid, error) {
func (pp *polBox) CreateZettel(ctx context.Context, zettel zettel.Zettel) (id.Zid, error) {
	user := server.GetUser(ctx)
	if pp.policy.CanCreate(user, zettel.Meta) {
		return pp.box.CreateZettel(ctx, zettel)
	}
	return id.Invalid, box.NewErrNotAllowed("Create", user, id.Invalid)
}

func (pp *polBox) GetZettel(ctx context.Context, zid id.Zid) (domain.Zettel, error) {
	zettel, err := pp.box.GetZettel(ctx, zid)
func (pp *polBox) GetZettel(ctx context.Context, zid id.Zid) (zettel.Zettel, error) {
	z, err := pp.box.GetZettel(ctx, zid)
	if err != nil {
		return domain.Zettel{}, err
		return zettel.Zettel{}, err
	}
	user := server.GetUser(ctx)
	if pp.policy.CanRead(user, zettel.Meta) {
		return zettel, nil
	if pp.policy.CanRead(user, z.Meta) {
		return z, nil
	}
	return domain.Zettel{}, box.NewErrNotAllowed("GetZettel", user, zid)
	return zettel.Zettel{}, box.NewErrNotAllowed("GetZettel", user, zid)
}

func (pp *polBox) GetAllZettel(ctx context.Context, zid id.Zid) ([]domain.Zettel, error) {
func (pp *polBox) GetAllZettel(ctx context.Context, zid id.Zid) ([]zettel.Zettel, error) {
	return pp.box.GetAllZettel(ctx, zid)
}

func (pp *polBox) GetMeta(ctx context.Context, zid id.Zid) (*meta.Meta, error) {
	m, err := pp.box.GetMeta(ctx, zid)
	if err != nil {
		return nil, err

func (pp *polBox) SelectMeta(ctx context.Context, q *query.Query) ([]*meta.Meta, error) {
	user := server.GetUser(ctx)
	canRead := pp.policy.CanRead
	q = q.SetPreMatch(func(m *meta.Meta) bool { return canRead(user, m) })
	return pp.box.SelectMeta(ctx, q)
}

func (pp *polBox) CanUpdateZettel(ctx context.Context, zettel domain.Zettel) bool {
func (pp *polBox) CanUpdateZettel(ctx context.Context, zettel zettel.Zettel) bool {
	return pp.box.CanUpdateZettel(ctx, zettel)
}

func (pp *polBox) UpdateZettel(ctx context.Context, zettel domain.Zettel) error {
func (pp *polBox) UpdateZettel(ctx context.Context, zettel zettel.Zettel) error {
	zid := zettel.Meta.Zid
	user := server.GetUser(ctx)
	if !zid.IsValid() {
		return &box.ErrInvalidID{Zid: zid}
	}
	// Write existing zettel
	oldMeta, err := pp.box.GetMeta(ctx, zid)

//-----------------------------------------------------------------------------

package policy

import (
	"zettelstore.de/c/api"
	"zettelstore.de/z/auth"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/zettel/meta"
)

type defaultPolicy struct {
	manager auth.AuthzManager
}

func (*defaultPolicy) CanCreate(_, _ *meta.Meta) bool { return true }

package policy

import (
	"zettelstore.de/c/api"
	"zettelstore.de/z/auth"
	"zettelstore.de/z/config"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/zettel/meta"
)

type ownerPolicy struct {
	manager    auth.AuthzManager
	authConfig config.AuthConfig
	pre        auth.Policy
}

// Package policy provides some interfaces and implementation for authorizsation policies.
package policy

import (
	"zettelstore.de/z/auth"
	"zettelstore.de/z/config"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/zettel/meta"
)

// newPolicy creates a policy based on given constraints.
func newPolicy(manager auth.AuthzManager, authConfig config.AuthConfig) auth.Policy {
	var pol auth.Policy
	if manager.IsReadonly() {
		pol = &roPolicy{}

import (
	"fmt"
	"testing"

	"zettelstore.de/c/api"
	"zettelstore.de/z/auth"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func TestPolicies(t *testing.T) {
	t.Parallel()
	testScene := []struct {
		readonly bool
		withAuth bool

//-----------------------------------------------------------------------------
// Copyright (c) 2020-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 policy

import "zettelstore.de/z/domain/meta"
import "zettelstore.de/z/zettel/meta"

type roPolicy struct{}

func (*roPolicy) CanCreate(_, _ *meta.Meta) bool   { return false }
func (*roPolicy) CanRead(_, _ *meta.Meta) bool     { return true }
func (*roPolicy) CanWrite(_, _, _ *meta.Meta) bool { return false }
func (*roPolicy) CanRename(_, _ *meta.Meta) bool   { return false }
func (*roPolicy) CanDelete(_, _ *meta.Meta) bool   { return false }
func (*roPolicy) CanRefresh(user *meta.Meta) bool  { return user != nil }

	"context"
	"errors"
	"fmt"
	"io"
	"time"

	"zettelstore.de/c/api"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/query"
	"zettelstore.de/z/query"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

// 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

	// 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 domain.Zettel) (id.Zid, error)
	CreateZettel(ctx context.Context, zettel zettel.Zettel) (id.Zid, error)

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

	// GetMeta retrieves just the meta data of a specific zettel.
	GetMeta(ctx context.Context, zid id.Zid) (*meta.Meta, error)

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

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

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

	// SelectMeta returns a list of metadata that comply to the given selection criteria.
	SelectMeta(ctx context.Context, q *query.Query) ([]*meta.Meta, error)

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

	// GetAllMeta retrieves the meta data of a specific zettel from all managed boxes.
	GetAllMeta(ctx context.Context, zid id.Zid) ([]*meta.Meta, error)

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

import (
	"context"
	"net/url"

	"zettelstore.de/c/api"
	"zettelstore.de/z/box"
	"zettelstore.de/z/box/manager"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/logger"
	"zettelstore.de/z/query"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	manager.Register(
		" comp",
		func(u *url.URL, cdata *manager.ConnectData) (box.ManagedBox, error) {
			return getCompBox(cdata.Number, cdata.Enricher), nil

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

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

func (*compBox) CanCreateZettel(context.Context) bool { return false }

func (cb *compBox) CreateZettel(context.Context, domain.Zettel) (id.Zid, error) {
func (cb *compBox) CreateZettel(context.Context, zettel.Zettel) (id.Zid, error) {
	cb.log.Trace().Err(box.ErrReadOnly).Msg("CreateZettel")
	return id.Invalid, box.ErrReadOnly
}

func (cb *compBox) GetZettel(_ context.Context, zid id.Zid) (domain.Zettel, error) {
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("GetMeta/Content")
				return domain.Zettel{
				return zettel.Zettel{
					Meta:    m,
					Content: domain.NewContent(genContent(m)),
					Content: zettel.NewContent(genContent(m)),
				}, nil
			}
			cb.log.Trace().Msg("GetMeta/NoContent")
			return domain.Zettel{Meta: m}, nil
			return zettel.Zettel{Meta: m}, nil
		}
	}
	cb.log.Trace().Err(box.ErrNotFound).Msg("GetZettel/Err")
	return domain.Zettel{}, box.ErrNotFound
	return zettel.Zettel{}, box.ErrNotFound
}

func (cb *compBox) GetMeta(_ context.Context, zid id.Zid) (*meta.Meta, error) {
	if gen, ok := myZettel[zid]; ok {
		if genMeta := gen.meta; genMeta != nil {
			if m := genMeta(zid); m != nil {
				updateMeta(m)

				handle(m)
			}
		}
	}
	return nil
}

func (*compBox) CanUpdateZettel(context.Context, domain.Zettel) bool { return false }
func (*compBox) CanUpdateZettel(context.Context, zettel.Zettel) bool { return false }

func (cb *compBox) UpdateZettel(context.Context, domain.Zettel) error {
func (cb *compBox) UpdateZettel(context.Context, zettel.Zettel) error {
	cb.log.Trace().Err(box.ErrReadOnly).Msg("UpdateZettel")
	return box.ErrReadOnly
}

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

package compbox

import (
	"bytes"

	"zettelstore.de/c/api"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func genConfigZettelM(zid id.Zid) *meta.Meta {
	if myConfig == nil {
		return nil
	}
	m := meta.New(zid)

package compbox

import (
	"bytes"
	"fmt"

	"zettelstore.de/c/api"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func genKeysM(zid id.Zid) *meta.Meta {
	m := meta.New(zid)
	m.Set(api.KeyTitle, "Zettelstore Supported Metadata Keys")
	m.Set(api.KeyCreated, kernel.Main.GetConfig(kernel.CoreService, kernel.CoreVTime).(string))
	m.Set(api.KeyVisibility, api.ValueVisibilityLogin)

package compbox

import (
	"bytes"

	"zettelstore.de/c/api"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

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))

package compbox

import (
	"bytes"
	"fmt"

	"zettelstore.de/c/api"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func genManagerM(zid id.Zid) *meta.Meta {
	m := meta.New(zid)
	m.Set(api.KeyTitle, "Zettelstore Box Manager")
	m.Set(api.KeyCreated, kernel.Main.GetConfig(kernel.CoreService, kernel.CoreStarted).(string))
	return m

import (
	"bytes"
	"fmt"
	"sort"
	"strings"

	"zettelstore.de/c/api"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/parser"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/parser"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func genParserM(zid id.Zid) *meta.Meta {
	m := meta.New(zid)
	m.Set(api.KeyTitle, "Zettelstore Supported Parser")
	m.Set(api.KeyCreated, kernel.Main.GetConfig(kernel.CoreService, kernel.CoreVTime).(string))
	m.Set(api.KeyVisibility, api.ValueVisibilityLogin)

// under this license.
//-----------------------------------------------------------------------------

package compbox

import (
	"zettelstore.de/c/api"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func getVersionMeta(zid id.Zid, title string) *meta.Meta {
	m := meta.New(zid)
	m.Set(api.KeyTitle, title)
	m.Set(api.KeyVisibility, api.ValueVisibilityExpert)
	return m

<link rel="stylesheet" href="{{{CSSUserURL}}}">
{{#CSSRoleURL}}<link rel="stylesheet" href="{{{CSSRoleURL}}}">{{/CSSRoleURL}}
<title>{{Title}}</title>
</head>
<body>
<nav class="zs-menu">
<a href="{{{HomeURL}}}">Home</a>
{{#WithUser}}
{{#WithAuth}}
<div class="zs-dropdown">
<button>User</button>
<nav class="zs-dropdown-content">
{{#WithAuth}}
{{#UserIsValid}}
<a href="{{{UserZettelURL}}}">{{UserIdent}}</a>
<a href="{{{LogoutURL}}}">Logout</a>
{{/UserIsValid}}
{{^UserIsValid}}
<a href="{{{LoginURL}}}">Login</a>
{{/UserIsValid}}
{{#UserIsValid}}
<a href="{{{LogoutURL}}}">Logout</a>
{{/UserIsValid}}
{{/WithAuth}}
</nav>
</div>
{{/WithUser}}
{{/WithAuth}}
<div class="zs-dropdown">
<button>Lists</button>
<nav class="zs-dropdown-content">
<a href="{{{ListZettelURL}}}">List Zettel</a>
<a href="{{{ListRolesURL}}}">List Roles</a>
<a href="{{{ListTagsURL}}}">List Tags</a>
{{#CanRefresh}}

(@@@@
(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)))
  ,@(if css-role-url `((link (@ (rel "stylesheet") (href ,css-role-url)))))
  (title ,title))
(body
  (nav (@ (class "zs-menu"))
    (a (@ (href ,home-url)) "Home")
    ,@(if with-auth
      `((div (@ (class "zs-dropdown"))
        (button "User")
        (nav (@ (class "zs-dropdown-content"))
          ,@(if user-is-valid
            `((a (@ (href ,user-zettel-url)) ,user-ident)
              (a (@ (href ,logout-url)) "Logout"))
            `((a (@ (href ,login-url)) "Login"))
          )
      )))
    )
    (div (@ (class "zs-dropdown"))
      (button "Lists")
      (nav (@ (class "zs-dropdown-content"))
        (a (@ (href ,list-zettel-url)) "List Zettel")
        (a (@ (href ,list-roles-url)) "List Roles")
        (a (@ (href ,list-tags-url)) "List Tags")
        ,@(if can-refresh `((a (@ (href ,refresh-url)) "Refresh")))
    ))
    ,@(if new-zettel-links
      `((div (@ (class "zs-dropdown"))
        (button "New")
        (nav (@ (class "zs-dropdown-content"))
          ,@(map pair-to-href new-zettel-links)
       )))
    )
    (form (@ (action ,search-url))
      (input (@ (type "text") (placeholder "Search..") (name ,query-key-query))))
  )
  (main (@ (class "content")) ,DETAIL)
  ,@(if FOOTER `((footer (hr) ,@FOOTER)))
  ,@(if debug-mode '((div (b "WARNING: Debug mode is enabled. DO NOT USE IN PRODUCTION!"))))
)))

	"context"
	_ "embed" // Allow to embed file content
	"net/url"

	"zettelstore.de/c/api"
	"zettelstore.de/z/box"
	"zettelstore.de/z/box/manager"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/logger"
	"zettelstore.de/z/query"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	manager.Register(
		" const",
		func(u *url.URL, cdata *manager.ConnectData) (box.ManagedBox, error) {
			return &constBox{
				log: kernel.Main.GetLogger(kernel.BoxService).Clone().
					Str("box", "const").Int("boxnum", int64(cdata.Number)).Child(),
				number:   cdata.Number,
				zettel:   constZettelMap,
				enricher: cdata.Enricher,
			}, nil
		})
}

type constHeader map[string]string

type constZettel struct {
	header  constHeader
	content domain.Content
	content zettel.Content
}

type constBox struct {
	log      *logger.Logger
	number   int
	zettel   map[id.Zid]constZettel
	enricher box.Enricher
}

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

func (*constBox) CanCreateZettel(context.Context) bool { return false }

func (cb *constBox) CreateZettel(context.Context, domain.Zettel) (id.Zid, error) {
func (cb *constBox) CreateZettel(context.Context, zettel.Zettel) (id.Zid, error) {
	cb.log.Trace().Err(box.ErrReadOnly).Msg("CreateZettel")
	return id.Invalid, box.ErrReadOnly
}

func (cb *constBox) GetZettel(_ context.Context, zid id.Zid) (domain.Zettel, error) {
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 domain.Zettel{Meta: meta.NewWithData(zid, z.header), Content: z.content}, nil
		return zettel.Zettel{Meta: meta.NewWithData(zid, z.header), Content: z.content}, nil
	}
	cb.log.Trace().Err(box.ErrNotFound).Msg("GetZettel")
	return domain.Zettel{}, box.ErrNotFound
	return zettel.Zettel{}, box.ErrNotFound
}

func (cb *constBox) GetMeta(_ context.Context, zid id.Zid) (*meta.Meta, error) {
	if z, ok := cb.zettel[zid]; ok {
		cb.log.Trace().Msg("GetMeta")
		return meta.NewWithData(zid, z.header), nil
	}

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

func (*constBox) CanUpdateZettel(context.Context, domain.Zettel) bool { return false }
func (*constBox) CanUpdateZettel(context.Context, zettel.Zettel) bool { return false }

func (cb *constBox) UpdateZettel(context.Context, domain.Zettel) error {
func (cb *constBox) UpdateZettel(context.Context, zettel.Zettel) error {
	cb.log.Trace().Err(box.ErrReadOnly).Msg("UpdateZettel")
	return box.ErrReadOnly
}

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

		constHeader{
			api.KeyTitle:      "Zettelstore Runtime Configuration",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxNone,
			api.KeyCreated:    "20200804111624",
			api.KeyVisibility: api.ValueVisibilityOwner,
		},
		domain.NewContent(nil)},
		zettel.NewContent(nil)},
	id.MustParse(api.ZidLicense): {
		constHeader{
			api.KeyTitle:      "Zettelstore License",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxText,
			api.KeyCreated:    "20210504135842",
			api.KeyLang:       api.ValueLangEN,
			api.KeyModified:   "20220131153422",
			api.KeyReadOnly:   api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityPublic,
		},
		domain.NewContent(contentLicense)},
		zettel.NewContent(contentLicense)},
	id.MustParse(api.ZidAuthors): {
		constHeader{
			api.KeyTitle:      "Zettelstore Contributors",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxZmk,
			api.KeyCreated:    "20210504135842",
			api.KeyLang:       api.ValueLangEN,
			api.KeyReadOnly:   api.ValueTrue,
			api.KeyVisibility: api.ValueVisibilityLogin,
		},
		domain.NewContent(contentContributors)},
		zettel.NewContent(contentContributors)},
	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.ValueVisibilityLogin,
			api.KeyCreated:    "20210504135842",
			api.KeyModified:   "20221013105100",
		},
		domain.NewContent(contentDependencies)},
		zettel.NewContent(contentDependencies)},
	id.BaseTemplateZid + 30000: {
		constHeader{
			api.KeyTitle:      "Zettelstore Base HTML Template (Mustache)",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeyCreated:    "20210504135842",
			api.KeyModified:   "20230523142249",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		zettel.NewContent(contentBaseMustache)},
	id.BaseTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Base HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeyCreated:    "20210504135842",
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20230510155100",
			api.KeyModified:   "20230523144403",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentBaseMustache)},
		zettel.NewContent(contentBaseSxn)},
	id.LoginTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Login Form HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20200804111624",
			api.KeyModified:   "20230527144100",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentLoginMustache)},
		zettel.NewContent(contentLoginSxn)},
	id.ZettelTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Zettel HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeyCreated:    "20200804111624",
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20230510155300",
			api.KeyModified:   "20230523212800",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentZettelMustache)},
		zettel.NewContent(contentZettelSxn)},
	id.InfoTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Info HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeyCreated:    "20200804111624",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentInfoMustache)},
		zettel.NewContent(contentInfoMustache)},
	id.ContextTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Context HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeyCreated:    "20210218181140",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentContextMustache)},
	id.FormTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Form HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20200804111624",
			api.KeyModified:   "20230528210200",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentFormMustache)},
		zettel.NewContent(contentFormSxn)},
	id.RenameTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Rename Form HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20200804111624",
			api.KeyModified:   "20230528174800",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentRenameMustache)},
		zettel.NewContent(contentRenameSxn)},
	id.DeleteTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Delete HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20200804111624",
			api.KeyModified:   "20230528154900",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentDeleteMustache)},
		zettel.NewContent(contentDeleteSxn)},
	id.ListTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore List Zettel HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeyCreated:    "20200804111624",
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20230526221600",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentListZettelMustache)},
		zettel.NewContent(contentListZettelSxn)},
	id.ErrorTemplateZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Error HTML Template",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxMustache,
			api.KeySyntax:     meta.SyntaxSxn,
			api.KeyCreated:    "20210305133215",
			api.KeyModified:   "20230527224800",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(contentErrorMustache)},
		zettel.NewContent(contentErrorSxn)},
	id.MustParse(api.ZidBaseCSS): {
		constHeader{
			api.KeyTitle:      "Zettelstore Base CSS",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxCSS,
			api.KeyCreated:    "20200804111624",
			api.KeyVisibility: api.ValueVisibilityPublic,
		},
		domain.NewContent(contentBaseCSS)},
		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,
		},
		domain.NewContent([]byte("/* User-defined CSS */"))},
		zettel.NewContent([]byte("/* User-defined CSS */"))},
	id.RoleCSSMapZid: {
		constHeader{
			api.KeyTitle:      "Zettelstore Role to CSS Map",
			api.KeyRole:       api.ValueRoleConfiguration,
			api.KeySyntax:     meta.SyntaxNone,
			api.KeyCreated:    "20220321183214",
			api.KeyVisibility: api.ValueVisibilityExpert,
		},
		domain.NewContent(nil)},
		zettel.NewContent(nil)},
	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,
		},
		domain.NewContent(contentEmoji)},
		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.KeyVisibility: api.ValueVisibilityCreator,
		},
		domain.NewContent(contentNewTOCZettel)},
		zettel.NewContent(contentNewTOCZettel)},
	id.MustParse(api.ZidTemplateNewZettel): {
		constHeader{
			api.KeyTitle:      "New Zettel",
			api.KeyRole:       api.ValueRoleZettel,
			api.KeySyntax:     meta.SyntaxZmk,
			api.KeyCreated:    "20201028185209",
			api.KeyVisibility: api.ValueVisibilityCreator,
		},
		domain.NewContent(nil)},
		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,
		},
		domain.NewContent(nil)},
		zettel.NewContent(nil)},
	id.DefaultHomeZid: {
		constHeader{
			api.KeyTitle:   "Home",
			api.KeyRole:    api.ValueRoleZettel,
			api.KeySyntax:  meta.SyntaxZmk,
			api.KeyLang:    api.ValueLangEN,
			api.KeyCreated: "20210210190757",
		},
		domain.NewContent(contentHomeZettel)},
		zettel.NewContent(contentHomeZettel)},
}

//go:embed license.txt
var contentLicense []byte

//go:embed contributors.zettel
var contentContributors []byte

//go:embed dependencies.zettel
var contentDependencies []byte

//go:embed base.mustache
var contentBaseMustache []byte

//go:embed base.sxn
var contentBaseSxn []byte

//go:embed login.mustache
var contentLoginMustache []byte
//go:embed login.sxn
var contentLoginSxn []byte

//go:embed zettel.mustache
var contentZettelMustache []byte
//go:embed zettel.sxn
var contentZettelSxn []byte

//go:embed info.mustache
var contentInfoMustache []byte

//go:embed context.mustache
var contentContextMustache []byte

//go:embed form.mustache
var contentFormMustache []byte
//go:embed form.sxn
var contentFormSxn []byte

//go:embed rename.mustache
var contentRenameMustache []byte
//go:embed rename.sxn
var contentRenameSxn []byte

//go:embed delete.mustache
var contentDeleteMustache []byte
//go:embed delete.sxn
var contentDeleteSxn []byte

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

//go:embed error.mustache
var contentErrorMustache []byte
//go:embed error.sxn
var contentErrorSxn []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 home.zettel
var contentHomeZettel []byte

<article>
<header>
<h1>{{Title}}</h1>
<div class="zs-meta">
<a href="{{{InfoURL}}}">Info</a>
&#183; <a href="?dir=backward">Backward</a>
&#183; <a href="?dir=both">Both</a>
&#183; <a href="?dir=forward">Forward</a>
&#183; Cost:{{#Costs}}&#x2000;<a href="{{{URL}}}">{{{Text}}}</a>{{/Costs}}
</div>
</header>
{{{Content}}}
</article>

<article>
<header>
<h1>Delete Zettel {{Zid}}</h1>
</header>
<p>Do you really want to delete this zettel?</p>
{{#HasShadows}}
<div class="zs-info">
<h2>Infomation</h2>
<p>If you delete this zettel, the previoulsy shadowed zettel from overlayed box {{ShadowedBox}} becomes available.</p>
</div>
{{/HasShadows}}
{{#Incoming.Has}}
<div class="zs-warning">
<h2>Warning!</h2>
<p>If you delete this zettel, incoming references from the following zettel will become invalid.</p>
<ul>
{{#Incoming.Links}}
<li><a href="{{{URL}}}">{{Text}}</a></li>
{{/Incoming.Links}}
</ul>
</div>
{{/Incoming.Has}}
{{#HasUselessFiles}}
<div class="zs-warning">
<h2>Warning!</h2>
<p>Deleting this zettel will also delete the following files, so that they will not be interpreted as content for this zettel.</p>
<ul>
{{#UselessFiles}}
<li>{{{.}}}</li>
{{/UselessFiles}}
</ul>
</div>
{{/HasUselessFiles}}
<dl>
{{#MetaPairs}}
<dt>{{Key}}:</dt><dd>{{Value}}</dd>
{{/MetaPairs}}
</dl>
<form method="POST">
<input class="zs-primary" type="submit" value="Delete">
</form>
</article>

(article
  (header (h1 "Delete Zettel " ,zid))
  (p "Do you really want to delete this zettel?")
  ,@(if shadowed-box
    `((div (@ (class "zs-info"))
      (h2 "Information")
      (p "If you delete this zettel, the previously shadowed zettel from overlayed box " ,shadowed-box " becomes available.")
    ))
  )
  ,@(if incoming
    `((div (@ (class "zs-warning"))
      (h2 "Warning!")
      (p "If you delete this zettel, incoming references from the following zettel will become invalid.")
      (ul ,@(map pair-to-href-li incoming))
    ))
  )
  ,@(if useless
    `((div (@ (class "zs-warning"))
      (h2 "Warning!")
      (p "Deleting this zettel will also delete the following files, so that they will not be interpreted as content for this zettel.")
      (ul ,@(map (lambda (s) `(li ,s)) useless))
    ))
  )
  ,(pairs-to-dl meta-pairs)
  (form (@ (method "POST")) (input (@ (class "zs-primary") (type "submit") (value "Delete"))))
)

<article>
<header>
<h1>{{ErrorTitle}}</h1>
</header>
{{ErrorText}}
</article>

(article
  (header (h1 ,heading))
  ,message
)

<article>
<header>
<h1>{{Heading}}</h1>
</header>
<form action="{{FormActionURL}}" method="POST" enctype="multipart/form-data">
<div>
<label for="zs-title">Title <a title="Main heading of this zettel. You can use inline zettelmarkup.">&#9432;</a></label>
<input class="zs-input" type="text" id="zs-title" name="title" placeholder="Title.." value="{{MetaTitle}}" autofocus>
</div>
<div>
<div>
<label for="zs-role">Role <a title="One word, without spaces, to set the main role of this zettel.">&#9432;</a></label>
<input class="zs-input" type="text" id="zs-role" {{#HasRoleData}}list="zs-role-data"{{/HasRoleData}} name="role" placeholder="role.." value="{{MetaRole}}">
{{#HasRoleData}}
<datalist id="zs-role-data">
{{#RoleData}}
<option value="{{.}}">
{{/RoleData}}
</datalist>
{{/HasRoleData}}
</div>
<label for="zs-tags">Tags <a title="Tags must begin with an '#' sign. They are separated by spaces.">&#9432;</a></label>
<input class="zs-input" type="text" id="zs-tags" name="tags" placeholder="#tag" value="{{MetaTags}}">
</div>
<div>
<label for="zs-meta">Metadata <a title="Other metadata for this zettel. Each line contains a key/value pair, separated by a colon ':'.">&#9432;</a></label>
<textarea class="zs-input" id="zs-meta" name="meta" rows="4" placeholder="metakey: metavalue">
{{#MetaPairsRest}}
{{Key}}: {{Value}}
{{/MetaPairsRest}}
</textarea>
</div>
<div>
<label for="zs-syntax">Syntax <a title="Syntax of zettel content below, one word. Typically 'zmk' (for zettelmarkup).">&#9432;</a></label>
<input class="zs-input" type="text" id="zs-syntax" {{#HasSyntaxData}}list="zs-syntax-data"{{/HasSyntaxData}} name="syntax" placeholder="syntax.." value="{{MetaSyntax}}">
{{#HasSyntaxData}}
<datalist id="zs-syntax-data">
{{#SyntaxData}}
<option value="{{.}}">
{{/SyntaxData}}
</datalist>
{{/HasSyntaxData}}</div>
<div>
{{#IsTextContent}}
<label for="zs-content">Content <a title="Content for this zettel, according to above syntax.">&#9432;</a></label>
<textarea class="zs-input zs-content" id="zs-content" name="content" rows="20" placeholder="Your content..">{{Content}}</textarea>
{{/IsTextContent}}
</div>
<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">
</div>
</form>
</article>

(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) (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)
      ,@(if role-data '((list "zs-role-data")))
    ))
    ,@(if role-data
      `((datalist (@ (id "zs-role-data"))
        ,@(map (lambda (v) `(option (@ (value ,v)))) 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))))
  (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")) ,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)
      ,@(if syntax-data '((list "zs-syntax-data")))
    ))
    ,@(if syntax-data
      `((datalist (@ (id "zs-syntax-data"))
        ,@(map (lambda (v) `(option (@ (value ,v)))) 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..")) ,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")))
  ))
)

</tr>
{{/ParseMatrix}}
</table>
{{#HasShadowLinks}}
<h2>Shadowed Boxes</h2>
<ul>{{#ShadowLinks}}<li>{{.}}</li>{{/ShadowLinks}}</ul>
{{/HasShadowLinks}}
{{#Endnotes}}{{{Endnotes}}}{{/Endnotes}}
</article>

<article>
<header>
<h1>{{Title}}</h1>
</header>
<form action="{{{SearchURL}}}">
<input class="zs-input" type="text" placeholder="Search.." name="{{QueryKeyQuery}}" value="{{QueryValue}}">
</form>
{{{Content}}}
{{#CanCreate}}<form action="{{{CreateURL}}}">
<input type="hidden" name="{{QueryKeyQuery}}" value="{{QueryValue}}">
<input type="hidden" name="{{QueryKeySeed}}" value="{{Seed}}">
<input class="zs-primary" type="submit" value="Save As Zettel">
</form>{{/CanCreate}}
</article>

(article
  (header (h1 ,heading))
  (form (@ (action ,search-url))
    (input (@ (class "zs-input") (type "text") (placeholder "Search..") (name ,query-key-query) (value ,query-value))))
  ,@content
  ,@endnotes
  ,@(if can-create
    `((form (@ (action ,create-url))
      (input (@ (type "hidden") (name ,query-key-query) (value ,query-value)))
      (input (@ (type "hidden") (name ,query-key-seed) (value ,seed)))
      (input (@ (class "zs-primary") (type "submit") (value "Save As Zettel")))
    ))
  )
)

<article>
<header>
<h1>{{Title}}</h1>
</header>
{{#Retry}}
<div class="zs-indication zs-error">Wrong user name / password. Try again.</div>
{{/Retry}}
<form method="POST" action="">
<div>
<label for="username">User name:</label>
<input class="zs-input" type="text" id="username" name="username" placeholder="Your user name.." autofocus>
</div>
<div>
<label for="password">Password:</label>
<input class="zs-input" type="password" id="password" name="password" placeholder="Your password..">
</div>
<div><input class="zs-primary" type="submit" value="Login"></div>
</form>
</article>

(article
  (header (h1 ,heading))
  ,@(if retry '((div (@ (class "zs-indication zs-error")) "Wrong user name / password. Try again.")))
  (form (@ (method "POST") (action ""))
    (div
      (label (@ (for "username")) "User name:")
      (input (@ (class "zs-input") (type "text") (id "username") (name "username") (placeholder "Your user name..") (autofocus))))
    (div
      (label (@ (for "password")) "Password:")
      (input (@ (class "zs-input") (type "password") (id "password") (name "password") (placeholder "Your password.."))))
    (div
      (input (@ (class "zs-primary") (type "submit") (value "Login"))))
  )
)

<article>
<header>
<h1>Rename Zettel {{Zid}}</h1>
</header>
<p>Do you really want to rename this zettel?</p>
{{#Incoming.Has}}
<div class="zs-warning">
<h2>Warning!</h2>
<p>If you rename this zettel, incoming references from the following zettel will become invalid.</p>
<ul>
{{#Incoming.Links}}
<li><a href="{{{URL}}}">{{Text}}</a></li>
{{/Incoming.Links}}
</ul>
</div>
{{/Incoming.Has}}
{{#HasUselessFiles}}
<div class="zs-warning">
<h2>Warning!</h2>
<p>Renaming this zettel will also delete the following files, so that they will not be interpreted as content for a zettel with identifier {{Zid}}.</p>
<ul>
{{#UselessFiles}}
<li>{{{.}}}</li>
{{/UselessFiles}}
</ul>
</div>
{{/HasUselessFiles}}
<form method="POST">
<div>
<label for="newid">New zettel id</label>
<input class="zs-input" type="text" id="newzid" name="newzid" placeholder="ZID.." value="{{Zid}}" autofocus>
</div>
<input type="hidden" id="curzid" name="curzid" value="{{Zid}}">
<div><input class="zs-primary" type="submit" value="Rename"></div>
</form>
<dl>
{{#MetaPairs}}
<dt>{{Key}}:</dt><dd>{{Value}}</dd>
{{/MetaPairs}}
</dl>
</article>

(article
  (header (h1 "Rename Zettel " ,zid))
  (p "Do you really want to rename this zettel?")
  ,@(if incoming
    `((div (@ (class "zs-warning"))
      (h2 "Warning!")
      (p "If you rename this zettel, incoming references from the following zettel will become invalid.")
      (ul ,@(map pair-to-href-li incoming))
    ))
  )
  ,@(if useless
    `((div (@ (class "zs-warning"))
      (h2 "Warning!")
      (p "Renaming this zettel will also delete the following files, so that they will not be interpreted as content for this zettel.")
      (ul ,@(map (lambda (s) `(li ,s)) useless))
    ))
  )
  (form (@ (method "POST"))
    (input (@ (type "hidden" (id "curzid") (name "curzid") (value ,zid))))
    (div
      (label (@ (for "newid") "New zettel id"))
      (input (@ (class "zs-input") (type "text") (id "newid") (name "newid") (placeholder "ZID..") (value ,zid) (autofocus))))
    (div (input (@ (class "zs-primary") (type "submit") (value "Rename"))))
  )
  ,(pairs-to-dl meta-pairs)
)

<article>
<header>
<h1>{{Heading}}</h1>
<div class="zs-meta">
{{#CanWrite}}<a href="{{{EditURL}}}">Edit</a> &#183;{{/CanWrite}}
{{Zid}} &#183;
<a href="{{{InfoURL}}}">Info</a> &#183;
(<a href="{{{RoleURL}}}">{{RoleText}}</a>)
{{#Tags.Has}}&#183; {{#Tags.Links}} <a href="{{{URL}}}">{{Text}}</a>{{/Tags.Links}}{{/Tags.Has}}
{{#CanCopy}}&#183; <a href="{{{CopyURL}}}">Copy</a>{{/CanCopy}}
{{#CanVersion}}&#183; <a href="{{{VersionURL}}}">Version</a>{{/CanVersion}}
{{#CanFolge}}&#183; <a href="{{{FolgeURL}}}">Folge</a>{{/CanFolge}}
{{#PredecessorRefs}}<br>Predecessor: {{{PredecessorRefs}}}{{/PredecessorRefs}}
{{#PrecursorRefs}}<br>Precursor: {{{PrecursorRefs}}}{{/PrecursorRefs}}
{{#HasExtURL}}<br>URL: {{{ExtURL}}}{{/HasExtURL}}
{{#Author}}<br>By {{Author}}{{/Author}}
</div>
</header>
{{{Content}}}
</article>
{{#NeedBottomNav}}<nav>{{/NeedBottomNav}}
{{#FolgeLinks.Has}}
<details open>
<summary>Folgezettel</summary>
<ul>
{{#FolgeLinks.Links}}
<li><a href="{{{URL}}}">{{Text}}</a></li>
{{/FolgeLinks.Links}}
</ul>
</details>
{{/FolgeLinks.Has}}
{{#BackLinks.Has}}
<details open>
<summary>Incoming</summary>
<ul>
{{#BackLinks.Links}}
<li><a href="{{{URL}}}">{{Text}}</a></li>
{{/BackLinks.Links}}
</ul>
</details>
{{/BackLinks.Has}}
{{#SuccessorLinks.Has}}
<details open>
<summary>Successors</summary>
<ul>
{{#SuccessorLinks.Links}}
<li><a href="{{{URL}}}">{{Text}}</a></li>
{{/SuccessorLinks.Links}}
</ul>
</details>
{{/SuccessorLinks.Has}}
{{#NeedBottomNav}}</nav>{{/NeedBottomNav}}

(article
  (header
    (h1 ,heading)
    (div (@ (class "zs-meta"))
      ,@(if can-write `((a (@ (href ,edit-url)) "Edit") (@H " · ")))
      ,zid (@H " · ")
      (a (@ (href ,info-url)) "Info") (@H " · ")
      "(" (a (@ (href ,role-url)) ,meta-role) ")"
      ,@(if tag-refs `((@H " · ") ,@tag-refs))
      ,@(if can-copy `((@H " · ") (a (@ (href ,copy-url)) "Copy")))
      ,@(if can-version `((@H " · ") (a (@ (href ,version-url)) "Version")))
      ,@(if can-folge `((@H " · ") (a (@ (href ,folge-url)) "Folge")))
      ,@(if predecessor-refs `((br) "Predecessor: " ,predecessor-refs))
      ,@(if precursor-refs `((br) "Precursor: " ,precursor-refs))
      ,@(if superior-refs `((br) "Superior: " ,superior-refs))
      ,@(if ext-url `((br) "URL: " ,ext-url))
      ,@(let (author (and (bound? 'meta-author) meta-author)) (if author `((br) "By " ,author)))
    )
  )
  ,@content
  ,endnotes
  ,@(if (or folge-links subordinate-links back-links successor-links)
    `((nav
      ,@(if folge-links `((details (@ (open)) (summary "Folgezettel") (ul ,@(map pair-to-href-li folge-links)))))
      ,@(if subordinate-links `((details (@ (open)) (summary "Subordinates") (ul ,@(map pair-to-href-li subordinate-links)))))
      ,@(if back-links `((details (@ (open)) (summary "Incoming") (ul ,@(map pair-to-href-li back-links)))))
      ,@(if successor-links `((details (@ (open)) (summary "Successors") (ul ,@(map pair-to-href-li successor-links)))))
     ))
  )
)

	"os"
	"path/filepath"
	"sync"

	"zettelstore.de/z/box"
	"zettelstore.de/z/box/manager"
	"zettelstore.de/z/box/notify"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/logger"
	"zettelstore.de/z/query"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	manager.Register("dir", func(u *url.URL, cdata *manager.ConnectData) (box.ManagedBox, error) {
		var log *logger.Logger
		if krnl := kernel.Main; krnl != nil {
			log = krnl.GetLogger(kernel.BoxService).Clone().Str("box", "dir").Int("boxnum", int64(cdata.Number)).Child()

	return dp.fCmds[sum%dp.fSrvs]
}

func (dp *dirBox) CanCreateZettel(_ context.Context) bool {
	return !dp.readonly
}

func (dp *dirBox) CreateZettel(ctx context.Context, zettel domain.Zettel) (id.Zid, error) {
func (dp *dirBox) CreateZettel(ctx context.Context, zettel zettel.Zettel) (id.Zid, error) {
	if dp.readonly {
		return id.Invalid, box.ErrReadOnly
	}

	newZid, err := dp.dirSrv.SetNewDirEntry()
	if err != nil {
		return id.Invalid, err

		err = dp.dirSrv.UpdateDirEntry(&entry)
	}
	dp.notifyChanged(meta.Zid)
	dp.log.Trace().Err(err).Zid(meta.Zid).Msg("CreateZettel")
	return meta.Zid, err
}

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

func (dp *dirBox) GetMeta(ctx context.Context, zid id.Zid) (*meta.Meta, error) {
	m, err := dp.doGetMeta(ctx, zid)
	dp.log.Trace().Zid(zid).Err(err).Msg("GetMeta")

		}
		dp.cdata.Enricher.Enrich(ctx, m, dp.number)
		handle(m)
	}
	return nil
}

func (dp *dirBox) CanUpdateZettel(context.Context, domain.Zettel) bool {
func (dp *dirBox) CanUpdateZettel(context.Context, zettel.Zettel) bool {
	return !dp.readonly
}

func (dp *dirBox) UpdateZettel(ctx context.Context, zettel domain.Zettel) error {
func (dp *dirBox) UpdateZettel(ctx context.Context, zettel zettel.Zettel) error {
	if dp.readonly {
		return box.ErrReadOnly
	}

	meta := zettel.Meta
	zid := meta.Zid
	if !zid.IsValid() {

	if err == nil {
		dp.notifyChanged(zid)
	}
	dp.log.Trace().Zid(zid).Err(err).Msg("UpdateZettel")
	return err
}

func (dp *dirBox) updateEntryFromMetaContent(entry *notify.DirEntry, m *meta.Meta, content domain.Content) {
func (dp *dirBox) updateEntryFromMetaContent(entry *notify.DirEntry, m *meta.Meta, content zettel.Content) {
	entry.SetupFromMetaContent(m, content, dp.cdata.Config.GetZettelFileSyntax)
}

func (dp *dirBox) AllowRenameZettel(context.Context, id.Zid) bool {
	return !dp.readonly
}

	}

	newEntry, err := dp.dirSrv.RenameDirEntry(curEntry, newZid)
	if err != nil {
		return err
	}
	oldMeta.Zid = newZid
	newZettel := domain.Zettel{Meta: oldMeta, Content: domain.NewContent(oldContent)}
	newZettel := zettel.Zettel{Meta: oldMeta, Content: zettel.NewContent(oldContent)}
	if err = dp.srvSetZettel(ctx, &newEntry, newZettel); err != nil {
		// "Rollback" rename. No error checking...
		dp.dirSrv.RenameDirEntry(&newEntry, curZid)
		return err
	}
	err = dp.srvDeleteZettel(ctx, curEntry, curZid)
	if err == nil {

	"io"
	"os"
	"path/filepath"
	"time"

	"zettelstore.de/z/box/filebox"
	"zettelstore.de/z/box/notify"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/input"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/logger"
	"zettelstore.de/z/zettel"
	"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 r := recover(); r != nil {
			kernel.Main.LogRecover("FileService", r)

	cmd.rc <- resGetMetaContent{m, content, err}
}

// COMMAND: srvSetZettel ----------------------------------------
//
// Writes a new or exsting zettel.

func (dp *dirBox) srvSetZettel(ctx context.Context, entry *notify.DirEntry, zettel domain.Zettel) error {
func (dp *dirBox) srvSetZettel(ctx context.Context, entry *notify.DirEntry, zettel zettel.Zettel) error {
	rc := make(chan resSetZettel, 1)
	dp.getFileChan(zettel.Meta.Zid) <- &fileSetZettel{entry, zettel, rc}
	ctx, cancel := context.WithTimeout(ctx, serviceTimeout)
	defer cancel()
	select {
	case err := <-rc:
		return err
	case <-ctx.Done():
		return ctx.Err()
	}
}

type fileSetZettel struct {
	entry  *notify.DirEntry
	zettel domain.Zettel
	zettel zettel.Zettel
	rc     chan<- resSetZettel
}
type resSetZettel = error

func (cmd *fileSetZettel) run(log *logger.Logger, dirPath string) {
	entry := cmd.entry
	zid := entry.Zid

	"net/url"
	"path/filepath"
	"strings"

	"zettelstore.de/c/api"
	"zettelstore.de/z/box"
	"zettelstore.de/z/box/manager"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	manager.Register("file", func(u *url.URL, cdata *manager.ConnectData) (box.ManagedBox, error) {
		path := getFilepathFromURL(u)
		ext := strings.ToLower(filepath.Ext(path))
		if ext != ".zip" {

	"archive/zip"
	"context"
	"io"
	"strings"

	"zettelstore.de/z/box"
	"zettelstore.de/z/box/notify"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/input"
	"zettelstore.de/z/logger"
	"zettelstore.de/z/query"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

type zipBox struct {
	log      *logger.Logger
	number   int
	name     string
	enricher box.Enricher

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

func (*zipBox) CanCreateZettel(context.Context) bool { return false }

func (zb *zipBox) CreateZettel(context.Context, domain.Zettel) (id.Zid, error) {
func (zb *zipBox) CreateZettel(context.Context, zettel.Zettel) (id.Zid, error) {
	err := box.ErrReadOnly
	zb.log.Trace().Err(err).Msg("CreateZettel")
	return id.Invalid, err
}

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

	var m *meta.Meta
	var src []byte
	var inMeta bool

	contentName := entry.ContentName
	if metaName := entry.MetaName; metaName == "" {
		if contentName == "" {
			zb.log.Panic().Zid(zid).Msg("No meta, no content in zipBox.GetZettel")
		}
		src, err = readZipFileContent(reader, entry.ContentName)
		if err != nil {
			return domain.Zettel{}, err
			return zettel.Zettel{}, err
		}
		if entry.HasMetaInContent() {
			inp := input.NewInput(src)
			m = meta.NewFromInput(zid, inp)
			src = src[inp.Pos:]
		} else {
			m = CalcDefaultMeta(zid, entry.ContentExt)
		}
	} else {
		m, err = readZipMetaFile(reader, zid, metaName)
		if err != nil {
			return domain.Zettel{}, err
			return zettel.Zettel{}, err
		}
		inMeta = true
		if contentName != "" {
			src, err = readZipFileContent(reader, entry.ContentName)
			if err != nil {
				return domain.Zettel{}, err
				return zettel.Zettel{}, err
			}
		}
	}

	CleanupMeta(m, zid, entry.ContentExt, inMeta, entry.UselessFiles)
	zb.log.Trace().Zid(zid).Msg("GetZettel")
	return domain.Zettel{Meta: m, Content: domain.NewContent(src)}, nil
	return zettel.Zettel{Meta: m, Content: zettel.NewContent(src)}, nil
}

func (zb *zipBox) GetMeta(_ context.Context, zid id.Zid) (*meta.Meta, error) {
	entry := zb.dirSrv.GetDirEntry(zid)
	if !entry.IsValid() {
		return nil, box.ErrNotFound
	}

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

func (*zipBox) CanUpdateZettel(context.Context, domain.Zettel) bool { return false }
func (*zipBox) CanUpdateZettel(context.Context, zettel.Zettel) bool { return false }

func (zb *zipBox) UpdateZettel(context.Context, domain.Zettel) error {
func (zb *zipBox) UpdateZettel(context.Context, zettel.Zettel) error {
	err := box.ErrReadOnly
	zb.log.Trace().Err(err).Msg("UpdateZettel")
	return err
}

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

package box

import (
	"net/url"
	"strconv"
	"time"

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

// GetNewZid calculates a new and unused zettel identifier, based on the current date and time.
func GetNewZid(testZid func(id.Zid) (bool, error)) (id.Zid, error) {
	withSeconds := false
	for i := 0; i < 90; i++ { // Must be completed within 9 seconds (less than web/server.writeTimeout)
		zid := id.New(withSeconds)

//-----------------------------------------------------------------------------

package manager

import (
	"sync"

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

type arAction int

const (
	arNothing arAction = iota
	arReload

//-----------------------------------------------------------------------------

package manager

import (
	"testing"

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

func TestSimple(t *testing.T) {
	t.Parallel()
	ar := newAnterooms(2)
	ar.EnqueueZettel(id.Zid(1))
	action, zid, rno := ar.Dequeue()

import (
	"context"
	"errors"
	"strings"

	"zettelstore.de/z/box"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/query"
	"zettelstore.de/z/query"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

// Conatains all box.Box related functions

// Location returns some information where the box is located.
func (mgr *Manager) Location() string {
	if len(mgr.boxes) <= 2 {

func (mgr *Manager) CanCreateZettel(ctx context.Context) bool {
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	return mgr.State() == box.StartStateStarted && mgr.boxes[0].CanCreateZettel(ctx)
}

// CreateZettel creates a new zettel.
func (mgr *Manager) CreateZettel(ctx context.Context, zettel domain.Zettel) (id.Zid, error) {
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()
	return mgr.boxes[0].CreateZettel(ctx, zettel)
}

// GetZettel retrieves a specific zettel.
func (mgr *Manager) GetZettel(ctx context.Context, zid id.Zid) (domain.Zettel, error) {
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 domain.Zettel{}, box.ErrStopped
		return zettel.Zettel{}, box.ErrStopped
	}
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	for i, p := range mgr.boxes {
		if z, err := p.GetZettel(ctx, zid); err != box.ErrNotFound {
			if err == nil {
				mgr.Enrich(ctx, z.Meta, i+1)
			}
			return z, err
		}
	}
	return domain.Zettel{}, box.ErrNotFound
	return zettel.Zettel{}, box.ErrNotFound
}

// GetAllZettel retrieves a specific zettel from all managed boxes.
func (mgr *Manager) GetAllZettel(ctx context.Context, zid id.Zid) ([]domain.Zettel, error) {
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
	}
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	var result []domain.Zettel
	var result []zettel.Zettel
	for i, p := range mgr.boxes {
		if z, err := p.GetZettel(ctx, zid); err == nil {
			mgr.Enrich(ctx, z.Meta, i+1)
			result = append(result, z)
		}
	}
	return result, nil

		msg.Str("query", q.String()).Msg("SelectMeta")
	}
	if mgr.State() != box.StartStateStarted {
		return nil, box.ErrStopped
	}
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	return mgr.doSelectMeta(ctx, q)

	compSearch := q.RetrieveAndCompile(mgr)
}
func (mgr *Manager) doSelectMeta(ctx context.Context, q *query.Query) ([]*meta.Meta, error) {
	compSearch, err := q.RetrieveAndCompile(ctx, mgr, mgr.doGetMeta, mgr.doSelectMeta)
	if err != nil {
		return nil, err
	}
	if result := compSearch.Result(); result != nil {
		mgr.mgrLog.Trace().Int("count", int64(len(result))).Msg("found without ApplyMeta")
		return result, nil
	}
	selected := metaMap{}
	for _, term := range compSearch.Terms {
		rejected := id.Set{}
		handleMeta := func(m *meta.Meta) {
			zid := m.Zid
			if rejected.Contains(zid) {
				mgr.mgrLog.Trace().Zid(zid).Msg("SelectMeta/alreadyRejected")

				mgr.mgrLog.Trace().Zid(zid).Msg("SelectMeta/match")
			} else {
				rejected.Zid(zid)
				mgr.mgrLog.Trace().Zid(zid).Msg("SelectMeta/reject")
			}
		}
		for _, p := range mgr.boxes {
			if err := p.ApplyMeta(ctx, handleMeta, term.Retrieve); err != nil {
				return nil, err
			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)
	}
	return q.AfterSearch(result), nil
	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 domain.Zettel) bool {
func (mgr *Manager) CanUpdateZettel(ctx context.Context, zettel zettel.Zettel) bool {
	mgr.mgrMx.RLock()
	defer mgr.mgrMx.RUnlock()
	return mgr.State() == box.StartStateStarted && mgr.boxes[0].CanUpdateZettel(ctx, zettel)
}

// UpdateZettel updates an existing zettel.
func (mgr *Manager) UpdateZettel(ctx context.Context, zettel domain.Zettel) error {
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
	}
	// Remove all (computed) properties from metadata before storing the zettel.
	zettel.Meta = zettel.Meta.Clone()
	for _, p := range zettel.Meta.ComputedPairsRest() {

package manager

import (
	"strings"

	"zettelstore.de/z/ast"
	"zettelstore.de/z/box/manager/store"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/strfun"
	"zettelstore.de/z/strfun"
	"zettelstore.de/z/zettel/id"
)

type collectData struct {
	refs  id.Set
	words store.WordSet
	urls  store.WordSet
}

import (
	"context"
	"strconv"

	"zettelstore.de/c/api"
	"zettelstore.de/z/box"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

// Enrich computes additional properties and updates the given metadata.
func (mgr *Manager) Enrich(ctx context.Context, m *meta.Meta, boxNumber int) {

	// Calculate computed, but stored values.
	if _, ok := m.Get(api.KeyCreated); !ok {

	"context"
	"fmt"
	"net/url"
	"time"

	"zettelstore.de/z/box"
	"zettelstore.de/z/box/manager/store"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/parser"
	"zettelstore.de/z/strfun"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

// SearchEqual returns all zettel that contains the given exact word.
// The word must be normalized through Unicode NKFD, trimmed and not empty.
func (mgr *Manager) SearchEqual(word string) id.Set {
	found := mgr.idxStore.SearchEqual(word)
	mgr.idxLog.Debug().Str("word", word).Int("found", int64(len(found))).Msg("SearchEqual")

			<-timer.C
		}
		return false
	}
	return true
}

func (mgr *Manager) idxUpdateZettel(ctx context.Context, zettel domain.Zettel) {
func (mgr *Manager) idxUpdateZettel(ctx context.Context, zettel zettel.Zettel) {
	var cData collectData
	cData.initialize()
	collectZettelIndexData(parser.ParseZettel(ctx, zettel, "", mgr.rtConfig), &cData)

	m := zettel.Meta
	zi := store.NewZettelIndex(m.Zid)
	mgr.idxCollectFromMeta(ctx, m, zi, &cData)

	"zettelstore.de/c/maps"
	"zettelstore.de/z/auth"
	"zettelstore.de/z/box"
	"zettelstore.de/z/box/manager/memstore"
	"zettelstore.de/z/box/manager/store"
	"zettelstore.de/z/config"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/logger"
	"zettelstore.de/z/strfun"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

// ConnectData contains all administration related values.
type ConnectData struct {
	Number   int // number of the box, starting with 1.
	Config   config.Config
	Enricher box.Enricher

		mgr.setState(box.StartStateStopped)
		return err
	}
	mgr.idxAr.Reset() // Ensure an initial index run
	mgr.done = make(chan struct{})
	go mgr.notifier()

	for !mgr.allBoxesStarted() {
	mgr.waitBoxesAreStarted()
		mgr.mgrLog.Trace().Msg("Wait for boxes to start")
		time.Sleep(time.Second)
	}
	mgr.setState(box.StartStateStarted)
	mgr.notifyObserver(&box.UpdateInfo{Box: mgr, Reason: box.OnReady})

	go mgr.idxIndexer()
	return nil
}

func (mgr *Manager) waitBoxesAreStarted() {
	const waitTime = 10 * time.Millisecond
	const waitLoop = int(1 * time.Second / waitTime)
	for i := 1; !mgr.allBoxesStarted(); i++ {
		if i%waitLoop == 0 {
			if time.Duration(i)*waitTime > time.Minute {
				mgr.mgrLog.Warn().Msg("Waiting for more than one minute to start")
			} else {
				mgr.mgrLog.Trace().Msg("Wait for boxes to start")
			}
		}
		time.Sleep(waitTime)
	}
}

func (mgr *Manager) allBoxesStarted() bool {
	for _, bx := range mgr.boxes {
		if b, ok := bx.(box.StartStopper); ok && b.State() != box.StartStateStarted {
			return false
		}
	}

	"sort"
	"strings"
	"sync"

	"zettelstore.de/c/api"
	"zettelstore.de/c/maps"
	"zettelstore.de/z/box/manager/store"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

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

//-----------------------------------------------------------------------------
// 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 "zettelstore.de/z/domain/id"
import "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++

//-----------------------------------------------------------------------------

package memstore

import (
	"testing"

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

func assertRefs(t *testing.T, i int, got, exp id.Slice) {
	t.Helper()
	if got == nil && exp != nil {
		t.Errorf("%d: got nil, but expected %v", i, exp)
		return

// Package store contains general index data for storing a zettel index.
package store

import (
	"context"
	"io"

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

// Stats records statistics about the store.
type Stats struct {
	// Zettel is the number of zettel managed by the indexer.
	Zettel int

//-----------------------------------------------------------------------------
// 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 store

import "zettelstore.de/z/domain/id"
import "zettelstore.de/z/zettel/id"

// ZettelIndex contains all index data of a zettel.
type ZettelIndex struct {
	Zid      id.Zid            // zid of the indexed zettel
	backrefs id.Set            // set of back references
	metarefs map[string]id.Set // references to inverse keys
	deadrefs id.Set            // set of dead references

import (
	"context"
	"net/url"
	"sync"

	"zettelstore.de/z/box"
	"zettelstore.de/z/box/manager"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/logger"
	"zettelstore.de/z/query"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func init() {
	manager.Register(
		"mem",
		func(u *url.URL, cdata *manager.ConnectData) (box.ManagedBox, error) {
			return &memBox{

type memBox struct {
	log       *logger.Logger
	u         *url.URL
	cdata     manager.ConnectData
	maxZettel int
	maxBytes  int
	mx        sync.RWMutex // Protects the following fields
	zettel    map[id.Zid]domain.Zettel
	zettel    map[id.Zid]zettel.Zettel
	curBytes  int
}

func (mb *memBox) notifyChanged(zid id.Zid) {
	if chci := mb.cdata.Notify; chci != nil {
		chci <- box.UpdateInfo{Box: mb, Reason: box.OnZettel, Zid: zid}
	}

		return box.StartStateStopped
	}
	return box.StartStateStarted
}

func (mb *memBox) Start(context.Context) error {
	mb.mx.Lock()
	mb.zettel = make(map[id.Zid]domain.Zettel)
	mb.zettel = make(map[id.Zid]zettel.Zettel)
	mb.curBytes = 0
	mb.mx.Unlock()
	mb.log.Trace().Int("max-zettel", int64(mb.maxZettel)).Int("max-bytes", int64(mb.maxBytes)).Msg("Start Box")
	return nil
}

func (mb *memBox) Stop(context.Context) {
	mb.mx.Lock()
	mb.zettel = nil
	mb.mx.Unlock()
}

func (mb *memBox) CanCreateZettel(context.Context) bool {
	mb.mx.RLock()
	defer mb.mx.RUnlock()
	return len(mb.zettel) < mb.maxZettel
}

func (mb *memBox) CreateZettel(_ context.Context, zettel domain.Zettel) (id.Zid, error) {
func (mb *memBox) CreateZettel(_ context.Context, zettel zettel.Zettel) (id.Zid, error) {
	mb.mx.Lock()
	newBytes := mb.curBytes + zettel.Length()
	if mb.maxZettel < len(mb.zettel) || mb.maxBytes < newBytes {
		mb.mx.Unlock()
		return id.Invalid, box.ErrCapacity
	}
	zid, err := box.GetNewZid(func(zid id.Zid) (bool, error) {

	mb.curBytes = newBytes
	mb.mx.Unlock()
	mb.notifyChanged(zid)
	mb.log.Trace().Zid(zid).Msg("CreateZettel")
	return zid, nil
}

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

func (mb *memBox) GetMeta(_ context.Context, zid id.Zid) (*meta.Meta, error) {
	mb.mx.RLock()
	zettel, ok := mb.zettel[zid]
	mb.mx.RUnlock()
	if !ok {

			mb.cdata.Enricher.Enrich(ctx, m, mb.cdata.Number)
			handle(m)
		}
	}
	return nil
}

func (mb *memBox) CanUpdateZettel(_ context.Context, zettel domain.Zettel) bool {
func (mb *memBox) CanUpdateZettel(_ context.Context, zettel zettel.Zettel) bool {
	mb.mx.RLock()
	defer mb.mx.RUnlock()
	zid := zettel.Meta.Zid
	if !zid.IsValid() {
		return false
	}

	newBytes := mb.curBytes + zettel.Length()
	if prevZettel, found := mb.zettel[zid]; found {
		newBytes -= prevZettel.Length()
	}
	return newBytes < mb.maxBytes
}

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

	mb.mx.Lock()
	newBytes := mb.curBytes + zettel.Length()

	"fmt"
	"path/filepath"
	"regexp"
	"strings"
	"sync"

	"zettelstore.de/z/box"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/logger"
	"zettelstore.de/z/parser"
	"zettelstore.de/z/query"
	"zettelstore.de/z/strfun"
	"zettelstore.de/z/zettel/id"
)

type entrySet map[id.Zid]*DirEntry

// DirServiceState signal the internal state of the service.
//
// The following state transitions are possible:

//-----------------------------------------------------------------------------

package notify

import (
	"testing"

	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	_ "zettelstore.de/z/parser/blob"       // Allow to use BLOB parser.
	_ "zettelstore.de/z/parser/draw"       // Allow to use draw parser.
	_ "zettelstore.de/z/parser/markdown"   // Allow to use markdown parser.
	_ "zettelstore.de/z/parser/none"       // Allow to use none parser.
	_ "zettelstore.de/z/parser/plain"      // Allow to use plain parser.
	_ "zettelstore.de/z/parser/zettelmark" // Allow to use zettelmark parser.
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

func TestSeekZid(t *testing.T) {
	testcases := []struct {
		name string
		zid  id.Zid
	}{

package notify

import (
	"path/filepath"

	"zettelstore.de/c/api"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/parser"
	"zettelstore.de/z/parser"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

const (
	extZettel = "zettel" // file contains metadata and content
	extBin    = "bin"    // file contains binary content
	extTxt    = "txt"    // file contains non-binary content
)

// HasMetaInContent returns true, if metadata will be stored in the content file.
func (e *DirEntry) HasMetaInContent() bool {
	return e.IsValid() && extIsMetaAndContent(e.ContentExt)
}

// SetupFromMetaContent fills entry data based on metadata and zettel content.
func (e *DirEntry) SetupFromMetaContent(m *meta.Meta, content domain.Content, getZettelFileSyntax func() []string) {
func (e *DirEntry) SetupFromMetaContent(m *meta.Meta, content zettel.Content, getZettelFileSyntax func() []string) {
	if e.Zid != m.Zid {
		panic("Zid differ")
	}
	if contentName := e.ContentName; contentName != "" {
		if !extIsMetaAndContent(e.ContentExt) && e.MetaName == "" {
			e.MetaName = e.calcBaseName(contentName)
		}

		}
		if metaName == "" {
			e.MetaName = e.calcBaseName(e.ContentName)
		}
	}
}

func contentExtWithMeta(syntax string, content domain.Content) string {
func contentExtWithMeta(syntax string, content zettel.Content) string {
	p := parser.Get(syntax)
	if content.IsBinary() {
		if p.IsImageFormat {
			return syntax
		}
		return extBin
	}

	"context"
	"flag"
	"fmt"
	"io"
	"os"

	"zettelstore.de/c/api"
	"zettelstore.de/z/domain"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/encoder"
	"zettelstore.de/z/input"
	"zettelstore.de/z/parser"
	"zettelstore.de/z/zettel"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

// ---------- Subcommand: file -----------------------------------------------

func cmdFile(fs *flag.FlagSet) (int, error) {
	enc := fs.Lookup("t").Value.String()
	m, inp, err := getInput(fs.Args())
	if m == nil {
		return 2, err
	}
	z := parser.ParseZettel(
		context.Background(),
		domain.Zettel{
		zettel.Zettel{
			Meta:    m,
			Content: domain.NewContent(inp.Src[inp.Pos:]),
			Content: zettel.NewContent(inp.Src[inp.Pos:]),
		},
		m.GetDefault(api.KeySyntax, meta.SyntaxZmk),
		nil,
	)
	encdr := encoder.Create(api.Encoder(enc))
	if encdr == nil {
		fmt.Fprintf(os.Stderr, "Unknown format %q\n", enc)

	"fmt"
	"os"

	"golang.org/x/term"

	"zettelstore.de/c/api"
	"zettelstore.de/z/auth/cred"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/zettel/id"
)

// ---------- Subcommand: password -------------------------------------------

func cmdPassword(fs *flag.FlagSet) (int, error) {
	if fs.NArg() == 0 {
		fmt.Fprintln(os.Stderr, "User name and user zettel identification missing")

	"context"
	"flag"
	"net/http"

	"zettelstore.de/z/auth"
	"zettelstore.de/z/box"
	"zettelstore.de/z/config"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/usecase"
	"zettelstore.de/z/web/adapter/api"
	"zettelstore.de/z/web/adapter/webui"
	"zettelstore.de/z/web/server"
	"zettelstore.de/z/zettel/meta"
)

// ---------- Subcommand: run ------------------------------------------------

func flgRun(fs *flag.FlagSet) {
	fs.String("c", "", "configuration file")
	fs.Uint("a", 0, "port number kernel service (0=disable)")

	ucGetAllMeta := usecase.NewGetAllMeta(protectedBoxManager)
	ucGetZettel := usecase.NewGetZettel(protectedBoxManager)
	ucParseZettel := usecase.NewParseZettel(rtConfig, ucGetZettel)
	ucListMeta := usecase.NewListMeta(protectedBoxManager)
	ucEvaluate := usecase.NewEvaluate(rtConfig, ucGetZettel, ucGetMeta, ucListMeta)
	ucListSyntax := usecase.NewListSyntax(protectedBoxManager)
	ucListRoles := usecase.NewListRoles(protectedBoxManager)
	ucZettelContext := usecase.NewZettelContext(protectedBoxManager, rtConfig)
	ucDelete := usecase.NewDeleteZettel(logUc, protectedBoxManager)
	ucUpdate := usecase.NewUpdateZettel(logUc, protectedBoxManager)
	ucRename := usecase.NewRenameZettel(logUc, protectedBoxManager)
	ucUnlinkedRefs := usecase.NewUnlinkedReferences(protectedBoxManager, rtConfig)
	ucRefresh := usecase.NewRefresh(logUc, protectedBoxManager)
	ucVersion := usecase.NewVersion(kernel.Main.GetConfig(kernel.CoreService, kernel.CoreVersion).(string))

		webSrv.AddZettelRoute('c', server.MethodPost, wui.MakePostCreateZettelHandler(&ucCreateZettel))
		webSrv.AddZettelRoute('d', server.MethodGet, wui.MakeGetDeleteZettelHandler(ucGetMeta, ucGetAllMeta))
		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(ucListMeta, &ucEvaluate))
	webSrv.AddListRoute('h', server.MethodGet, wui.MakeListHTMLMetaHandler(ucListMeta))
	webSrv.AddZettelRoute('h', server.MethodGet, wui.MakeGetHTMLZettelHandler(&ucEvaluate, ucGetMeta))
	webSrv.AddListRoute('i', server.MethodGet, wui.MakeGetLoginOutHandler())
	webSrv.AddListRoute('i', server.MethodPost, wui.MakePostLoginHandler(&ucAuthenticate))
	webSrv.AddZettelRoute('i', server.MethodGet, wui.MakeGetInfoHandler(
		ucParseZettel, &ucEvaluate, ucGetMeta, ucGetAllMeta, ucUnlinkedRefs))
	webSrv.AddZettelRoute('k', server.MethodGet, wui.MakeZettelContextHandler(
		ucZettelContext, &ucEvaluate))

	// API
	webSrv.AddListRoute('a', server.MethodPost, a.MakePostLoginHandler(&ucAuthenticate))
	webSrv.AddListRoute('a', server.MethodPut, a.MakeRenewAuthHandler())
	webSrv.AddZettelRoute('o', server.MethodGet, a.MakeGetOrderHandler(
		usecase.NewZettelOrder(protectedBoxManager, ucEvaluate)))
	webSrv.AddZettelRoute('u', server.MethodGet, a.MakeListUnlinkedMetaHandler(ucGetMeta, ucUnlinkedRefs))
	webSrv.AddListRoute('x', server.MethodGet, a.MakeGetDataHandler(ucVersion))
	webSrv.AddListRoute('x', server.MethodPost, a.MakePostCommandHandler(&ucIsAuth, &ucRefresh))
	webSrv.AddZettelRoute('x', server.MethodGet, a.MakeZettelContextHandler(ucZettelContext))
	webSrv.AddListRoute('z', server.MethodGet, a.MakeQueryHandler(ucListMeta))
	webSrv.AddZettelRoute('z', server.MethodGet, a.MakeGetZettelHandler(ucGetMeta, 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))

	"zettelstore.de/c/api"
	"zettelstore.de/z/auth"
	"zettelstore.de/z/auth/impl"
	"zettelstore.de/z/box"
	"zettelstore.de/z/box/compbox"
	"zettelstore.de/z/box/manager"
	"zettelstore.de/z/config"
	"zettelstore.de/z/domain/id"
	"zettelstore.de/z/domain/meta"
	"zettelstore.de/z/input"
	"zettelstore.de/z/kernel"
	"zettelstore.de/z/logger"
	"zettelstore.de/z/web/server"
	"zettelstore.de/z/zettel/id"
	"zettelstore.de/z/zettel/meta"
)

const strRunSimple = "run-simple"

func init() {
	RegisterCommand(Command{
		Name: "help",

	_ "zettelstore.de/z/box/compbox"       // Allow to use computed box.
	_ "zettelstore.de/z/box/constbox"      // Allow to use global internal box.
	_ "zettelstore.de/z/box/dirbox"        // Allow to use directory box.
	_ "zettelstore.de/z/box/filebox"       // Allow to use file box.
	_ "zettelstore.de/z/box/membox"        // Allow to use in-memory box.
	_ "zettelstore.de/z/encoder/htmlenc"   // Allow to use HTML encoder.
	_ "zettelstore.de/z/encoder/mdenc"     // Allow to use markdown encoder.
	_ "zettelstore.de/z/encoder/sexprenc"  // Allow to use sexpr encoder.
	_ "zettelstore.de/z/encoder/shtmlenc"  // Allow to use SHTML encoder.
	_ "zettelstore.de/z/encoder/szenc"     // Allow to use Sz encoder.
	_ "zettelstore.de/z/encoder/textenc"   // Allow to use text encoder.
	_ "zettelstore.de/z/encoder/zmkenc"    // Allow to use zmk encoder.
	_ "zettelstore.de/z/kernel/impl"       // Allow kernel implementation to create itself
	_ "zettelstore.de/z/parser/blob"       // Allow to use BLOB parser.
	_ "zettelstore.de/z/parser/draw"       // Allow to use draw parser.
	_ "zettelstore.de/z/parser/markdown"   // Allow to use markdown parser.
	_ "zettelstore.de/z/parser/none"       // Allow to use none parser.
	_ "zettelstore.de/z/parser/plain"      // Allow to use plain parser.
	_ "zettelstore.de/z/parser/zettelmark" // Allow to use zettelmark parser.
)

// Package config provides functions to retrieve runtime configuration data.
package config

import (
	"context"

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

// Key values that are supported by Config.Get
const (
	KeyFooterZettel = "footer-zettel"
	KeyHomeZettel   = "home-zettel"
	// api.KeyLang

id: 20210916193200
title: Required Software
role: zettel
syntax: zmk
created: 20210916193200
modified: 20230327165135
modified: 20230405150541

The following software must be installed:

* A current, supported [[release of Go|https://go.dev/doc/devel/release]],
* [[shadow|https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/shadow]] via ``go install golang.org/x/tools/go/analysis/passes/shadow/cmd/shadow@latest``,
* [[staticcheck|https://staticcheck.io/]] via ``go install honnef.co/go/tools/cmd/staticcheck@latest``,
* [[unparam|https://mvdan.cc/unparam]][^[[GitHub|https://github.com/mvdan/unparam]]] via ``go install mvdan.cc/unparam@latest``,
* [[govulncheck|https://golang.org/x/vuln/cmd/govulncheck]] via ``go install golang.org/x/vuln/cmd/govulncheck@latest``,
* [[Fossil|https://fossil-scm.org/]],
* [[Git|https://git-scm.org/]] (most dependencies are accessible via Git only).

Make sure that the software is in your path, e.g. via:

```sh
export PATH=$PATH:/usr/local/go/bin
export PATH=$PATH:$(go env GOPATH)/bin
```

The internal build tool need the following software.
It can be installed / updated via the build tool itself: ``go run tools/build.go tools``.

Otherwise you can install the software by hand:

* [[shadow|https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/shadow]] via ``go install golang.org/x/tools/go/analysis/passes/shadow/cmd/shadow@latest``,
* [[staticcheck|https://staticcheck.io/]] via ``go install honnef.co/go/tools/cmd/staticcheck@latest``,
* [[unparam|https://mvdan.cc/unparam]][^[[GitHub|https://github.com/mvdan/unparam]]] via ``go install mvdan.cc/unparam@latest``,
* [[govulncheck|https://golang.org/x/vuln/cmd/govulncheck]] via ``go install golang.org/x/vuln/cmd/govulncheck@latest``,

id: 20210916194900
title: Checklist for Release
role: zettel
syntax: zmk
created: 20210916194900
modified: 20220309105459
modified: 20230402181229

# Sync with the official repository
#* ``fossil sync -u``
# Make sure that there is no workspace defined.
#* ``ls ..`` must not have a file ''go.work'', in no parent folder.
# Make sure that all dependencies are up-to-date.
#* ``cat go.mod``

# Clean up your Go workspace:
#* ``go run tools/build.go clean`` (alternatively: ``make clean``).
# Create the release:
#* ``go run tools/build.go release`` (alternatively: ``make release``).
# Remove previous executables:
#* ``fossil uv remove --glob '*-PREVVERSION*'``
# Add executables for release:
#* ``cd release``
#* ``cd releases``
#* ``fossil uv add *.zip``
#* ``cd ..``
#* Synchronize with main repository:
#* ``fossil sync -u``
# Enable autosync:
#* ``fossil setting autosync on``

```

; ''-t FORMAT''
: Specifies the output format.
  Supported values are:
  [[''html''|00001012920510]] (default),
  [[''md''|00001012920513]],
  [[''sexpr''|00001012920516]],
  [[''shtml''|00001012920525]],
  [[''sz''|00001012920516]],
  [[''text''|00001012920519]],
  and [[''zmk''|00001012920522]].
; ''file-1''
: Specifies the file name, where at least metadata is read.
  If ''file-2'' is not given, the zettel content is also read from here.
; ''file-2''
: File name where the zettel content is stored.

If neither ''file-1'' nor ''file-2'' are given, metadata and zettel content are read from standard input / stdin.

id: 00001006000000
title: Layout of a Zettel
role: manual
tags: #design #manual #zettelstore
syntax: zmk
created: 20210126175322
modified: 20221219162703
modified: 20230403123541

A zettel consists of two parts: the metadata and the zettel content.
Metadata gives some information mostly about the zettel content, how it should be interpreted, how it is sorted within Zettelstore.
The zettel content is, well, the actual content.
In many cases, the content is in plain text form.
Plain text is long-lasting.
However, content in binary format is also possible.

Other character encodings are not supported and will never be[^This is not a real problem, since every modern software should support UTF-8 as an encoding.].
There is support for a graphical format with a text representation: SVG.
And there is support for some binary image formats, like GIF, PNG, and JPEG.

=== Plain, parsed, and evaluated zettel
Zettelstore may present your zettel in various forms, typically retrieved with the [[endpoint|00001012920000]] ''/z/{ID}''.
One way is to present the zettel as it was read by Zettelstore.
This is called ""[[plain zettel|00001003000000]]"".
This is called ""[[plain zettel|00001012053300]]"".

The second way is to present the zettel as it was recognized by Zettelstore.
This is called ""[[parsed zettel|00001012053600]]"", also retrieved with the [[endpoint|00001012920000]] ''/z/{ID}'', but with additional query parameter.
This is called ""[[parsed zettel|00001012053600]]"", also retrieved with the [[endpoint|00001012920000]] ''/z/{ID}'', but with the additional query parameter ''parseonly''.
Such a zettel was read and analyzed.
It can be presented in various [[encodings|00001012920500]].[^The [[zmk encoding|00001012920522]] allows you to compare the plain, the parsed, and the evaluated form of a zettel.]

However, a zettel such as this one you are currently reading, is a ""[[evaluated zettel|00001012053500]]"", also retrieved with the [[endpoint|00001012920000]] ''/z/{ID}'' and specifying an encoding.
The biggest difference to a parsed zettel is the inclusion of [[block transclusions|00001007031100]] or [[inline transclusions|00001007040324]] for an evaluated zettel.
It can also be presented in various encoding, including the ""zmk"" encoding.
Evaluations also applies to metadata of a zettel, if appropriate.

Please note, that searching for content is based on parsed zettel.
Transcluded content will only be found in transcluded zettel, but not in the zettel that transcluded the content.
However, you will easily pick up that zettel by follow the [[backward|00001006020000#backward]] metadata key of the transcluded zettel.

id: 00001006020000
title: Supported Metadata Keys
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210126175322
modified: 20230320150950
modified: 20230421155051

Although you are free to define your own metadata, by using any key (according to the [[syntax|00001006010000]]), some keys have a special meaning that is enforced by Zettelstore.
See the [[computed list of supported metadata keys|00000000000090]] for details.

Most keys conform to a [[type|00001006030000]].

; [!author|''author'']

; [!credential|''credential'']
: Contains the hashed password, as it was emitted by [[``zettelstore password``|00001004051400]].
  It is internally created by hashing the password, the [[zettel identifier|00001006050000]], and the value of the ''ident'' key.

  It is only used for zettel with a ''role'' value of ""user"".
; [!dead|''dead'']
: Property that contains all references that does __not__ identify a zettel.
; [!expire|''expire'']
: A user-entered time stamp that document the point in time when the zettel should expire.
  When a zettel is expires, Zettelstore does nothing.
  It is up to you to define required actions.
  ''expire'' is just a documentation.
  You could define a query and execute it regularly, for example [[query:expire? ORDER expire]].
  Alternatively, a Zettelstore client software could define some actions when it detects expired zettel.
; [!folge|''folge'']
: Is a property that contains identifier of all zettel that reference this zettel through the [[''precursor''|#precursor]] value.
; [!forward|''forward'']
: Property that contains all references that identify another zettel within the content of the zettel.
; [!id|''id'']
: Contains the [[zettel identifier|00001006050000]], as given by the Zettelstore.
  It cannot be set manually, because it is a computed value.

: Marks a zettel as read-only.
  The interpretation of [[supported values|00001006020400]] for this key depends, whether authentication is [[enabled|00001010040100]] or not.
; [!role|''role'']
: Defines the role of the zettel.
  Can be used for selecting zettel.
  See [[supported zettel roles|00001006020100]].
  If not given, it is ignored.
; [!subordinates|''subordinates'']
: Is a property that contains identifier of all zettel that reference this zettel through the [[''superior''|#superior]] value.
; [!successors|''successors'']
: Is a property that contains identifier of all zettel that reference this zettel through the [[''predecessor''|#predecessor]] value.
  Therefore, it references all zettel that contain a new version of the content and/or metadata.
  In contrast to [[''folge''|#folge]], these are references because of technical reasons, not because of content-related reasons.
  In most cases, zettel referencing the current zettel should be updated to reference a successor zettel.
  The [[query reference|00001007040310]] [[query:backward? successors?]] lists all such zettel.
; [!summary|''summary'']
: Summarizes the content of the zettel.
  You may use all [[inline-structued elements|00001007040000]] of Zettelmarkup.
; [!superior|''superior'']
: Specifies a zettel that is conceptually a superior zettel.
  This might be a more abstract zettel, or a zettel that should be higher in a hierarchy.
; [!syntax|''syntax'']
: Specifies the syntax that should be used for interpreting the zettel.
  The zettel about [[other markup languages|00001008000000]] defines supported values.
  If it is not given, it defaults to ''plain''.
; [!tags|''tags'']
: Contains a space separated list of tags to describe the zettel further.
  Each Tag must begin with the number sign character (""''#''"", U+0023).

id: 00001006030000
title: Supported Key Types
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210126175322
modified: 20220304114106
modified: 20230402183536

All [[supported metadata keys|00001006020000]] conform to a type.

User-defined metadata keys conform also to a type, based on the suffix of the key.

|=Suffix|Type
| ''-date'' | [[Timestamp|00001006034500]]
| ''-number'' | [[Number|00001006033000]]
| ''-role'' | [[Word|00001006035500]]
| ''-set'' | [[WordSet|00001006036000]]
| ''-time'' | [[Timestamp|00001006034500]]
| ''-title'' | [[Zettelmarkup|00001006036500]]
| ''-url'' | [[URL|00001006035000]]
| ''-zettel''  | [[Identifier|00001006032000]]
| ''-zid''  | [[Identifier|00001006032000]]
| ''-zids''  | [[IdentifierSet|00001006032500]]
| any other suffix | [[EString|00001006031500]]

id: 00001006031000
title: Credential Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914130324
modified: 20230419175515

Values of this type denote a credential value, e.g. an encrypted password.

=== Allowed values
All printable characters are allowed.
Since a credential contains some kind of secret, the sequence of characters might have some hidden syntax to be interpreted by other parts of Zettelstore.

=== Query operators
=== Query comparison
A credential never compares to any other value.
A comparison will never match in any way.

=== Sorting
If a list of zettel should be sorted based on a credential value, the identifier of the respective zettel is used instead.

id: 00001006031500
title: EString Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914130448
modified: 20230419175525

Values of this type are just a sequence of character, possibly an empty sequence.

An EString is the most general metadata key type, as it places no restrictions to the character sequence.[^Well, there are some minor restrictions that follow from the [[metadata syntax|00001006010000]].]

=== Allowed values
All printable characters are allowed.

=== Query operator
=== Query comparison
All comparisons are done case-insensitive, i.e. ""hell"" will be the prefix of ""Hello"".

=== Sorting
To sort two values, the underlying encoding is used to determine which value is less than the other.

Uppercase letters are typically interpreted as less than their corresponding lowercase letters, i.e. ``A < a``.

Comparison is done character-wise by finding the first difference in the respective character sequence.
For example, ``abc > aBc``.

id: 00001006032000
title: Identifier Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914134914
modified: 20230419175535

Values of this type denote a [[zettel identifier|00001006050000]].

=== Allowed values
Must be a sequence of 14 digits (""0""--""9"").

=== Query operator
=== Query comparison
Comparison is done with the string representation of the identifiers.
For example, ""000010"" matches ""[[00001006032000]]"".

=== Sorting
Sorting is done by comparing the [[String|00001006033500]] values.

If both values are identifiers, this works well because both have the same length.

id: 00001006032500
title: IdentifierSet Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914131354
modified: 20230419175551

Values of this type denote a (sorted) set of [[zettel identifier|00001006050000]].

A set is different to a list, as no duplicate values are allowed.

=== Allowed values
Must be at least one sequence of 14 digits (""0""--""9""), separated by space characters.

=== Query operator
=== Query comparison
A value matches an identifier set value, if the value matches any of the identifier set values.

For example, ""000010060325"" is a prefix ""[[00001006032000]] [[00001006032500]]"".

=== Sorting
Sorting is done by comparing the [[String|00001006033500]] values.

id: 00001006033000
title: Number Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914131211
modified: 20230419175623

Values of this type denote a numeric integer value.

=== Allowed values
Must be a sequence of digits (""0""--""9""), optionally prefixed with a ""-"" or a ""+"" character.

=== Query operator
All comparisons are done on the given string representation of the number, ""+12"" will be treated as a different number of ""12"".
=== Query comparison
All comparisons are done on the given string representation of the number, ""+12"" will be treated as a different number ""12"".

=== Sorting
Sorting is done by comparing the numeric values.

id: 00001006033500
title: String Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914130505
modified: 20230419175633

Values of this type are just a sequence of character, but not an empty sequence.

=== Allowed values
All printable characters are allowed.
There must be at least one such character.

=== Query operator
=== Query comparison
All comparisons are done case-insensitive, i.e. ""hell"" will be the prefix of ""Hello"".

=== Sorting
To sort two values, the underlying encoding is used to determine which value is less than the other.

Uppercase letters are typically interpreted as less than their corresponding lowercase letters, i.e. ``A < a``.

Comparison is done character-wise by finding the first difference in the respective character sequence.
For example, ``abc > aBc``.

id: 00001006034000
title: TagSet Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914131048
modified: 20230419175642

Values of this type denote a (sorted) set of tags.

A set is different to a list, as no duplicate values are allowed.

=== Allowed values
Every tag must must begin with the number sign character (""''#''"", U+0023), followed by at least one printable character.
Tags are separated by space characters.

All characters are mapped to their lower case values.

=== Query operator
=== Query comparison
All comparisons are done case-sensitive, i.e. ""#hell"" will not be the prefix of ""#Hello"".

=== Sorting
Sorting is done by comparing the [[String|00001006033500]] values.

id: 00001006034500
title: Timestamp Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914130919
modified: 20230419175713

Values of this type denote a point in time.

=== Allowed values
Must be a sequence of 14 digits (""0""--""9"") (same as an [[Identifier|00001006032000]]), with the restriction that is conforms 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.

=== Query operator
=== Query comparison
All comparisons assume that up to 14 digits are given.
Comparison is done through the string representation.

=== Sorting
Sorting is done by comparing the [[String|00001006033500]] values.

If both values are timestamp values, this works well because both have the same length.

id: 00001006035000
title: URL Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914130809
modified: 20230419175725

Values of this type denote an URL.

=== Allowed values
All characters of an URL / URI are allowed.

=== Query operator
=== Query comparison
All comparisons are done case-insensitive.
For example, ""hello"" is the suffix of ""http://example.com/Hello"".

=== Sorting
Sorting is done by comparing the [[String|00001006033500]] values.

id: 00001006035500
title: Word Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914130655
modified: 20230419175735

Values of this type denote a single word.

=== Allowed values
Must be a non-empty sequence of characters, but without the space character.

All characters are mapped to their lower case values.

=== Query operator
=== Query comparison
All comparisons are done case-insensitive, i.e. ""hell"" will be the prefix of ""Hello"".

=== Sorting
Sorting is done by comparing the [[String|00001006033500]] values.

id: 00001006036000
title: WordSet Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914130725
modified: 20230419175745

Values of this type denote a (sorted) set of [[words|00001006035500]].

A set is different to a list, as no duplicate values are allowed.

=== Allowed values
Must be a sequence of at least one word, separated by space characters.

=== Query operator
=== Query comparison
All comparisons are done case-insensitive, i.e. ""hell"" will be the prefix of ""World, Hello"".

=== Sorting
Sorting is done by comparing the [[String|00001006033500]] values.

id: 00001006036500
title: Zettelmarkup Key Type
role: manual
tags: #manual #meta #reference #zettel #zettelstore
syntax: zmk
created: 20210212135017
modified: 20220914135405
modified: 20230419175441

Values of this type are [[String|00001006033500]] values, interpreted as [[Zettelmarkup|00001007000000]].

=== Allowed values
All printable characters are allowed.
There must be at least one such character.

=== Query operator
=== Query comparison
Comparison is done similar to the full-text search: both the value to compare and the metadata value are normalized according to Unicode NKFD, ignoring everything except letters and numbers.
Letters are mapped to the corresponding lower-case value.

For example, ""Brücke"" will be the prefix of ""(Bruckenpfeiler,"".

=== Sorting
To sort two values, the underlying encoding is used to determine which value is less than the other.

Uppercase letters are typically interpreted as less than their corresponding lowercase letters, i.e. ``A < a``.

Comparison is done character-wise by finding the first difference in the respective character sequence.
For example, ``abc > aBc``.

They begin with at least three tilde characters (""''~''"", U+007E) at the first position of a line.

You can add some [[attributes|00001007050000]] on the beginning line of a verbatim block, following the initiating characters.
The evaluation block supports the default attribute[^Depending on the syntax value.]: when given, all spaces in the text are rendered in HTML as open box characters (U+2423).
If you want to give only one attribute and this attribute is the generic attribute, you can omit the most of the attribute syntax and just specify the value.
It will be interpreted as a [[syntax|00001008000000]] value to evaluate its content.
Not all syntax values are supported by Zettelstore.[^Currently just ""[[draw|00001008050000]]"".]
The main reason for an evaluation block is to be used with external software via the [[Sexpr encoding|00001012920516]].
The main reason for an evaluation block is to be used with external software via the [[sz encoding|00001012920516]].

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 tilde characters in the text that should not be interpreted.

For example:

You can add some [[attributes|00001007050000]] on the beginning line of a verbatim block, following the initiating characters.
A math-mode block supports the default attribute[^Depending on the syntax value.]: when given, all spaces in the text are rendered in HTML as open box characters (U+2423).
If you want to give only one attribute and this attribute is the generic attribute, you can omit the most of the attribute syntax and just specify the value.
It will be interpreted as a [[syntax|00001008000000]] value to evaluate its content.
Alternatively, you could provide an attribute with the key ""syntax"" and use the value to specify the syntax.
Not all syntax values are supported by Zettelstore.[^Currently: none.]
External software might support several values via the [[Sexpr encoding|00001012920516]].
External software might support several values via the [[sz encoding|00001012920516]].

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 dollar-sign characters in the text that should not be interpreted.

For example:

id: 00001007700000
title: Query expression
role: manual
tags: #manual #search #zettelstore
syntax: zmk
created: 20220805150154
modified: 20220913135434
modified: 20230420190257

A query expression allows you to search for specific zettel and to perform some actions on them.
You may select zettel based on a full-text search, based on specific metadata values, or both.

A query expression consists of a __search expression__ and of an optional __action list__.
Both are separated by a vertical bar character (""''|''"", U+007C).
A query expression consists of an optional __context expression__, a __search expression__ and an optional __action list__.
The latter two are separated by a vertical bar character (""''|''"", U+007C).

A query expression follows a [[formal syntax|00001007780000]].

=== Context expression

An context expression starts with the keyword ''CONTEXT'', one or more space characters, and a [[zettel identifier|00001006050000]].

Optionally you may specify some context details, separated by space character. These are:
* ''BACKWARD'': search for context only though backward links,
* ''FORWARD'': search for context only through forward links,
* ''COST'', one or more space characters, and a positive integer: set the maximum __cost__ (default: 17),
* ''MAX'', one or more space characters, and a positive integer: set the maximum number of context zettel (default: 200).

If no ''BACKWARD'' and ''FORWARD'' is specified, a search for context zettel will be done though backward and forward links.

The cost of a context zettel is calculated iteratively:
* The specified zettel hast a cost of one.
* A zettel found as a single folge zettel or single precursor zettel has the cost of the originating zettel, plus one.
* A zettel found as a single successor zettel or single predecessor zettel has the cost of the originating zettel, plus two.
* A zettel found via another link without being part of a [[set of zettel identifier|00001006032500]], has the cost of the originating zettel, plus three.
* A zettel which is part of a set of zettel identifier, has the cost of the originating zettel, plus one of the three choices above and multiplied with roughly a logarithmic value based on the size of the set.
* A zettel with the same tag, has the cost of the originating zettel, plus the number of zettel with the same tag (if it is less than eight), or the cost of the originating zettel plus two, multiplied by number of zettel with the same tag divided by four.

Despite its possibly complicated structure, this algorithm ensures in practice that the zettel context is a list of zettel, where the first elements are ""near"" to the specified zettel and the last elements are more ""distant"" to the specified zettel.
It also penalties a zettel that acts as a ""hub"" to other zettel, to make it more likely that only relevant zettel appear on the context list.

=== Search expression

In its simplest form, a search expression just contains a string to be search for with the help of a full-text search.
For example, the string ''syntax'' will search for all zettel containing the word ""syntax"".

If you want to search for all zettel with a title containing the word ""syntax"", you must specify ''title:syntax''.
""title"" names the [[metadata key|00001006010000]], in this case the [[supported metadata key ""title""|00001006020000#title]].
The colon character (""'':''"") is a [[search operator|00001007705000]], in this example to specify a match.
""syntax"" is the [[search value|00001007706000]] that must match to the value of the given metadata key, here ""title"".

A search expression may contain more than one search term, such as ''title:syntax''.
Search terms must be separated by one or more space characters, for example ''title:syntax title:search''.
All terms of a select expression must be true so that a zettel is selected.

* [[Search terms|00001007702000]]
* [[Search operator|00001007705000]]
* [[Search value|00001007706000]]

Here are [[some examples|00001007790000]] of search expressions, which can be used to manage a Zettelstore:
Here are [[some examples|00001007790000]] of search / context expressions, which can be used to manage a Zettelstore:
{{{00001007790000}}}

=== Action List

With a search expression, a list of zettel is selected.
Actions allow to modify this list to a certain degree.

id: 00001007702000
title: Search term
role: manual
tags: #manual #search #zettelstore
syntax: zmk
created: 20220805150154
modified: 20230327123724
modified: 20230420153154

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]].

  Since search literals may be negated, it is possible to form any boolean search expression.
  Any search expression will be in a [[disjunctive normal form|https://en.wikipedia.org/wiki/Disjunctive_normal_form]].

  It has no effect on the following search terms initiated with a special uppercase word.
* The string ''PICK'', followed by a non-empty sequence of spaces and a number greater zero (called ""N"").

  This will pick randomly N elements of the result list.
  This will pick randomly N elements of the result list, preserving the order of that list.
  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 id ORDER created`` will be interpreted as ``ORDER id``.
* The string ''RANDOM'' will provide a random order of the resulting list.

  Currently, only the first term specifying the order of the resulting list will be used.
  Other ordering terms will be ignored.

  A random order specification will be ignored, if there is an explicit ordering given or if the specification contains a valid ''PICK''.
  A random order specification will be ignored, if there is an explicit ordering given.

  Example: ''RANDOM ORDER published'' will be interpreted as ''ORDER published'', ''PICK 3 RANDOM'' will be interpreted as ''PICK 3''.
  Example: ''RANDOM ORDER published'' will be interpreted as ''ORDER published''.
* The string ''OFFSET'', followed by a non-empty sequence of spaces and a number greater zero (called ""N"").

  This will ignore the first N elements of the result list, based on the specified sort order.
  A zero value of N will produce the same result as if nothing was specified.
  If specified multiple times, the higher value takes precedence.

  Example: ''OFFSET 4 OFFSET 8'' will be interpreted as ''OFFSET 8''.

This is resolved by the following rule:
* A search term containing no [[search operator character|00001007705000]] is treated as a full-text search.
* The first search operator character found in a search term divides the term into two pieces.
  If the first piece, from the beginning of the search term to the search operator character, is syntactically a metadata key, the search term is treated as a metadata-based search.
* Otherwise, the search term is treated as a full-text search.

If a term like ''PICK'', ''ORDER'', ''ORDER REVERSE'', ''OFFSET'', or ''LIMIT'' is not followed by an appropriate value, it is interpreted as a search value for a full-text search.
For example, ''ORDER 123'' will search for a zettel conatining the strings ""ORDER"" (case-insensitive) and ""123"".
For example, ''ORDER 123'' will search for a zettel containing the strings ""ORDER"" (case-insensitive) and ""123"".

A specification ''RANDOM LIMIT n'' (with some valid value of ''n'') will be interpreted as ''PICK n''.
Similar, a specification ''PICK n'', where ''n'' is greater or equal to the length of the result list, will be interpreted as ''RANDOM''.
A specification ''LIMIT n'', where ''n'' is greater or equal to the length of the result list, will be ignored effectively.

id: 00001007705000
title: Search operator
role: manual
tags: #manual #search #zettelstore
syntax: zmk
created: 20220805150154
modified: 20220819194709
modified: 20230419163812

A search operator specifies how the comparison of a search value and a zettel should be executed.
Every comparison is done case-insensitive, treating all uppercase letters the same as lowercase letters.

The following are allowed search operator characters:
* The exclamation mark character (""!"", U+0021) negates the meaning
* The exclamation mark character (""''!''"", U+0021) negates the meaning
* The equal sign character (""'' ''"", U+003D) compares on equal content (""equals operator"")
* The tilde character (""''~''"", U+007E) compares on matching (""match operator"")
* The greater-than sign character (""''>''"", U+003E) matches if there is some prefix (""prefix operator"")
* The less-than sign character (""''<''"", U+003C) compares a suffix relationship (""suffix operator"")
* The colon character (""'':''"", U+003A) compares on equal words (""has operator"")
* The colon character (""'':''"", U+003A) compares depending on the on the actual [[key type|00001006030000]] (""has operator"").
  In most cases, it acts as a equals operator, but for some type it acts as the match operator.
* The question mark (""''?''"", U+003F) checks for an existing metadata key (""exist operator"")

Since the exclamation mark character can be combined with the other, there are 10 possible combinations:
Since the exclamation mark character can be combined with the other, there are 14 possible combinations:
# ""''!''"": is an abbreviation of the ""''!~''"" operator.
# ""''~''"": is successful if the search value matched the value to be compared.
# ""''!~''"": is successful if the search value does not match the value to be compared.
# ""'':''"": is successful if the search value is equal to one word of the value to be compared.
# ""''!:''"": is successful if the search value is not equal to any word of the value to be compared.
# ""''=''"": is successful if the search value is equal to one word of the value to be compared.
# ""''!=''"": is successful if the search value is not equal to any word of the value to be compared.
# ""''>''"": is successful if the search value is a prefix of the value to be compared.
# ""''!>''"": is successful if the search value is not a prefix of the value to be compared.
# ""''<''"": is successful if the search value is a suffix of the value to be compared.
# ""''!<''"": is successful if the search value is not a suffix of the value to be compared.
# ""'':''"": is successful if the search value is has/match one word of the value to be compared.
# ""''!:''"": is successful if the search value is not match/has to any word of the value to be compared.
# ""''?''"": is successful if the metadata contains the given key.
# ""''!?''"": is successful if the metadata does not contain the given key.
# ""''''"": a missing search operator can only occur for a full-text search.
  It is equal to the ""''~''"" operator.

id: 00001007780000
title: Formal syntax of query expressions
role: manual
tags: #manual #reference #search #zettelstore
syntax: zmk
created: 20220810144539
modified: 20230327122634
modified: 20230411162000

```
QueryExpression  := SearchExpression ActionExpression?
SearchExpression := SearchTerm (SPACE+ SearchTerm)*.
SearchTerm       := SearchOperator? SearchValue
                  | SearchKey SearchOperator SearchValue?
                  | SearchKey ExistOperator
                  | "OR"
                  | "RANDOM"
                  | "PICK" SPACE+ PosInt
                  | "ORDER" SPACE+ ("REVERSE" SPACE+)? SearchKey
                  | "OFFSET" SPACE+ PosInt
                  | "LIMIT" SPACE+ PosInt.
SearchValue      := Word.
SearchKey        := MetadataKey.
SearchOperator   := '!'
                  | ('!')? ('~' | ':' | '<' | '>').
ExistOperator    := '?'
                  | '!' '?'.
PosInt           := '0'
                  | ('1' .. '9') DIGIT*.
ActionExpression := '|' (Word (SPACE+ Word)*)?
Word             := NO-SPACE NO-SPACE*
QueryExpression   := ContextExpression? SearchExpression ActionExpression?
ContextExpression := "CONTEXT" SPACE+ ZID (SPACE+ ContextDetail)*.
ContextDetail     := "BACKWARD"
                   | "FORWARD"
                   | "COST" SPACE+ PosInt
                   | "MAX" SPACE+ PosInt.
SearchExpression  := SearchTerm (SPACE+ SearchTerm)*.
SearchTerm        := SearchOperator? SearchValue
                   | SearchKey SearchOperator SearchValue?
                   | SearchKey ExistOperator
                   | "OR"
                   | "RANDOM"
                   | "PICK" SPACE+ PosInt
                   | "ORDER" SPACE+ ("REVERSE" SPACE+)? SearchKey
                   | "OFFSET" SPACE+ PosInt
                   | "LIMIT" SPACE+ PosInt.
SearchValue       := Word.
SearchKey         := MetadataKey.
SearchOperator    := '!'
                   | ('!')? ('~' | ':' | '<' | '>').
ExistOperator     := '?'
                   | '!' '?'.
PosInt            := '0'
                   | ('1' .. '9') DIGIT*.
ActionExpression  := '|' (Word (SPACE+ Word)*)?
Word              := NO-SPACE NO-SPACE*
```

id: 00001007790000
title: Useful query expressions
role: manual
tags: #example #manual #search #zettelstore
syntax: zmk
created: 20220810144539
modified: 20230327122547
modified: 20230420153334

|= Query Expression |= Meaning
| [[query:role:configuration]] | Zettel that contains some configuration data for the Zettelstore
| [[query:ORDER REVERSE created LIMIT 40]] | 40 recently created zettel
| [[query:ORDER REVERSE published LIMIT 40]] | 40 recently updated zettel
| [[query:PICK 40]] | 40 random zettel
| [[query:PICK 40]] | 40 random zettel, ordered by zettel identifier
| [[query:dead?]] | Zettel with invalid / dead links
| [[query:backward!? precursor!?]] | Zettel that are not referenced by other zettel
| [[query:tags!?]] | Zettel without tags
| [[query:expire? ORDER expire]] | Zettel with an expire date, ordered from the nearest to the latest
| [[query:CONTEXT 00001007700000]] | Zettel within the context of the [[given zettel|00001007700000]]

id: 00001008050000
title: The ""draw"" language
title: The "draw" language
role: manual
tags: #graphic #manual #zettelstore
syntax: zmk
created: 20220131142036
modified: 20220311120439
modified: 20230403123738

Sometimes, ""a picture is worth a thousand words"".
To create some graphical representations, Zettelmarkup provides a simple mechanism.
Characters like ""''|''"" or ""''-''"" already provide some visual feedback.
For example, to create a picture containing two boxes that are connected via an arrow, the following representation is possible:
```
~~~draw

id: 00001012000000
title: API
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210126175322
modified: 20221219150243
modified: 20230411164103

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 JSON as its main encoding format for exchanging messages between a Zettelstore and its client software.

=== 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]]
* [[Retrieve context of an existing zettel|00001012053800]]
* [[Retrieve unlinked references to an existing zettel|00001012053900]]
* [[Retrieve zettel order within an existing zettel|00001012054000]]
* [[Update metadata and content of a zettel|00001012054200]]
* [[Rename a zettel|00001012054400]]
* [[Delete a zettel|00001012054600]]

=== Various helper methods
* [[Retrieve administrative data|00001012070500]]
* [[Execute some commands|00001012080100]]
** [[Check for authentication|00001012080200]]
** [[Refresh internal data|00001012080500]]

id: 00001012050200
title: API: Authenticate a client
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210126175322
modified: 20220107215844
modified: 20230412150544

Authentication for future API calls is done by sending a [[user identification|00001010040200]] and a password to the Zettelstore to obtain an [[access token|00001010040700]].
This token has to be used for other API calls.
It is valid for a relatively short amount of time, as configured with the key ''token-lifetime-api'' of the [[startup configuration|00001004010000#token-lifetime-api]] (typically 10 minutes).

The simplest way is to send user identification (''IDENT'') and password (''PASSWORD'') via [[HTTP Basic Authentication|https://tools.ietf.org/html/rfc7617]] and send them to the [[endpoint|00001012920000]] ''/a'' with a POST request:
```sh
# curl -X POST -u IDENT:PASSWORD http://127.0.0.1:23123/a
{"access_token":"eyJhbGciOiJIUzUxMiJ9.eyJfdGsiOjEsImV4cCI6MTYwMTczMTI3NSwiaWF0IjoxNjAxNzMwNjc1LCJzdWIiOiJhYmMiLCJ6aWQiOiIyMDIwMTAwMzE1MDEwMCJ9.ekhXkvn146P2bMKFQcU-bNlvgbeO6sS39hs6U5EKfjIqnSInkuHYjYAIfUqf_clYRfr6YBlX5izii8XfxV8jhg","token_type":"Bearer","expires_in":600}
("Bearer" "eyJhbGciOiJIUzUxMiJ9.eyJfdGsiOjEsImV4cCI6MTY4MTMwNDA2MiwiaWF0IjoxNjgxMzA0MDAyLCJzdWIiOiJvd25lciIsInppZCI6IjIwMjEwNjI5MTYzMzAwIn0.kdF8PdiL50gIPkRD3ovgR6nUXR0-80EKAXcY2zVYgYvryF09iXnNR3zrvYnGzdrArMcnvAYqVvuXtqhQj2jG9g" 600)
```

Some tools, like [[curl|https://curl.haxx.se/]], also allow to specify user identification and password as part of the URL:
```sh
# curl -X POST http://IDENT:PASSWORD@127.0.0.1:23123/a
{"access_token":"eyJhbGciOiJIUzUxMiJ9.eyJfdGsiOjEsImV4cCI6MTYwMTczMTI3NSwiaWF0IjoxNjAxNzMwNjc1LCJzdWIiOiJhYmMiLCJ6aWQiOiIyMDIwMTAwMzE1MDEwMCJ9.ekhXkvn146P2bMKFQcU-bNlvgbeO6sS39hs6U5EKfjIqnSInkuHYjYAIfUqf_clYRfr6YBlX5izii8XfxV8jhg","token_type":"Bearer","expires_in":600}
("Bearer" "eyJhbGciOiJIUzUxMiJ9.eyJfdGsiOjEsImV4cCI6MTY4MTMwNDA4NiwiaWF0IjoxNjgxMzA0MDI2LCJzdWIiOiJvd25lciIsInppZCI6IjIwMjEwNjI5MTYzMzAwIn0.kZd3prYc79dt9efDsrYVHtKrjWyOWvfByjeeUB3hf_vs43V3SNJqmb8k-zTHVNWOK0-5orVPrg2tIAqbXqmkhg" 600)
```

If you do not want to use Basic Authentication, you can also send user identification and password as HTML form data:
```sh
# curl -X POST -d 'username=IDENT&password=PASSWORD' http://127.0.0.1:23123/a
{"access_token":"eyJhbGciOiJIUzUxMiJ9.eyJfdGsiOjEsImV4cCI6MTYwMTczMTI3NSwiaWF0IjoxNjAxNzMwNjc1LCJzdWIiOiJhYmMiLCJ6aWQiOiIyMDIwMTAwMzE1MDEwMCJ9.ekhXkvn146P2bMKFQcU-bNlvgbeO6sS39hs6U5EKfjIqnSInkuHYjYAIfUqf_clYRfr6YBlX5izii8XfxV8jhg","token_type":"Bearer","expires_in":600}
("Bearer" "eyJhbGciOiJIUzUxMiJ9.eyJfdGsiOjEsImV4cCI6MTY4MTMwNDA4OCwiaWF0IjoxNjgxMzA0MDI4LCJzdWIiOiJvd25lciIsInppZCI6IjIwMjEwNjI5MTYzMzAwIn0.qIEyOMFXykCApWtBaqbSESwTL96stWl2LRICiRNAXUjcY-mwx_SSl9L5Fj2FvmrI1K1RBvWehjoq8KZUNjhJ9Q" 600)
```

In all cases, you will receive an JSON object will all [[relevant data|00001012921000]] to be used for further API calls.
In all cases, you will receive a list with three elements that will contain all [[relevant data|00001012921000]] to be used for further API calls.

**Important:** obtaining a token is a time-intensive process.
Zettelstore will delay every request to obtain a token for a certain amount of time.
Please take into account that this request will take approximately 500 milliseconds, under certain circumstances more.

However, if [[authentication is not enabled|00001010040100]] and you send an authentication request, no user identification/password checking is done and you receive an artificial token immediate, without any delay:

```sh
# curl -X POST -u IDENT:PASSWORD http://127.0.0.1:23123/a
{"token":"freeaccess","token_type":"Bearer","expires_in":316224000}
("Bearer" "freeaccess" 316224000)
```

In this case, it is even possible to omit the user identification/password.

=== HTTP Status codes
In all cases of successful authentication, a JSON object is returned, which contains the token under the key ''"token"''.
In all cases of successful authentication, a list is returned, which contains the token as the second element.
A successful authentication is signaled with the HTTP status code 200, as usual.

Other status codes possibly send by the Zettelstore:
; ''400''
: Unable to process the request.
  In most cases the form data was invalid.
; ''401''
: Authentication failed.
  Either the user identification is invalid or you provided the wrong password.
; ''403''
: Authentication is not active.

id: 00001012050400
title: API: Renew an access token
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210126175322
modified: 20220107215751
modified: 20230412160219

An access token is only valid for a certain duration.
Since the [[authentication process|00001012050200]] will need some processing time, there is a way to renew the token without providing full authentication data.

Send a HTTP PUT request to the [[endpoint|00001012920000]] ''/a'' and include the current access token in the ''Authorization'' header:

```sh
# curl -X PUT -H 'Authorization: Bearer TOKEN' http://127.0.0.1:23123/a
{"access_token":"eyJhbGciOiJIUzUxMiJ9.eyJfdGsiOjEsImV4cCI6MTYwMTczMTI3NSwiaWF0IjoxNjAxNzMwNjc1LCJzdWIiOiJhYmMiLCJ6aWQiOiIyMDIwMTAwMzE1MDEwMCJ9.ekhXkvn146P2bMKFQcU-bNlvgbeO6sS39hs6U5EKfjIqnSInkuHYjYAIfUqf_clYRfr6YBlX5izii8XfxV8jhg","token_type":"Bearer","expires_in":456}
("Bearer" "eyJhbGciOiJIUzUxMiJ9.eyJfdGsiOjEsImV4cCI6MTY4MTMwNDA4NiwiaWF0IjoxNjgxMzA0MDI2LCJzdWIiOiJvd25lciIsInppZCI6IjIwMjEwNjI5MTYzMzAwIn0.kZd3prYc79dt9efDsrYVHtKrjWyOWvfByjeeUB3hf_vs43V3SNJqmb8k-zTHVNWOK0-5orVPrg2tIAqbXqmkhg" 456)
```
You may receive a new access token, or the current one if it was obtained not a long time ago.
However, the lifetime of the returned [[access token|00001012921000]] is accurate.

If [[authentication is not enabled|00001010040100]] and you send a renew request, no checking is done and you receive an artificial token immediate, without any delay:

```sh
# curl -X PUT -H 'Authorization: Bearer freeaccess' http://127.0.0.1:23123/a
{"token":"freeaccess","token_type":"Bearer","expires_in":316224000}
("Bearer" "freeaccess" 316224000)
```

In this case, it is even possible to omit the access token.

=== HTTP Status codes
; ''200''
: Renew process was successful, the body contains an [[appropriate JSON object|00001012921000]].
: Renew process was successful, the body contains a [[list|00001012921000]] with the relevant data.
; ''400''
: The renew process was not successful.
  There are several reasons for this.
  Maybe access bearer token was not valid.

  Probably you should [[authenticate|00001012050200]] again with user identification and password.

id: 00001012051200
title: API: List all zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210126175322
modified: 20221219154400
modified: 20230420160640

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:

```sh
# curl http://127.0.0.1:23123/z
...
00001012051200 API: List all zettel
00001012050600 API: Provide an access token
00001012050400 API: Renew an access token
00001012050200 API: Authenticate a client
...
```

The list is **not** sorted, even in the these examples where it appears to be sorted.
If you want to have it ordered, you must specify it with the help of a [[query expression|00001007700000]] / [[search term|00001007702000]].
See [[Query the list of all zettel|00001012051400]] how to do it.

Alternatively, you may retrieve the list of all zettel as a JSON object by specifying the encoding with the query parameter ''enc=json'':

```sh
# curl 'http://127.0.0.1:23123/z?enc=json'
{"query":"","human":"","list":[{"id":"00001012051200","meta":{"back":"00001012000000","backward":"00001012000000 00001012920000","box-number":"1","created":"20210126175322","forward":"00001006020000 00001006050000 00001007700000 00001010040100 00001012050200 00001012051400 00001012920000 00001012921000 00001014000000","modified":"20221219150626","published":"20221219150626","role":"manual","syntax":"zmk","tags":"#api #manual #zettelstore","title":"API: List all zettel"},"rights":62},{"id":"00001012050600","meta":{"back":"00001012000000 00001012080500","backward":"00001012000000 00001012080500","box-number":"1","created":"00010101000000","forward":"00001012050200 00001012921000","modified":"20220218130020","published":"20220218130020","role":"manual","syntax":"zmk","tags":"#api #manual #zettelstore","title":"API: Provide an access token"},"rights":62},{"id":"00001012050400","meta":{"back":"00001010040700 00001012000000","backward":"00001010040700 00001012000000 00001012920000 00001012921000","box-number":"1","created":"00010101000000","forward":"00001010040100 00001012050200 00001012920000 00001012921000","modified":"20220107215751","published":"20220107215751","role":"manual","syntax":"zmk","tags":"#api #manual #zettelstore","title":"API: Renew an access token"},"rights":62},{"id":"00001012050200","meta":{"back":"00001012000000 00001012050400 00001012050600 00001012051200 00001012051400 00001012053300 00001012053400 00001012053500 00001012053600 00001012080200","backward":"00001010040700 00001012000000 00001012050400 00001012050600 00001012051200 00001012051400 00001012053300 00001012053400 00001012053500 00001012053600 00001012080200 00001012920000 00001012921000","box-number":"1","created":"00010101000000","forward":"00001004010000 00001010040100 00001010040200 00001010040700 00001012920000 00001012921000","modified":"20220107215844","published":"20220107215844","role":"manual","syntax":"zmk","tags":"#api #manual #zettelstore","title":"API: Authenticate a client"},"rights":62}, ...]}
```

        "title": "API: Authenticate a client"
      },
      "rights": 62
    }
  ]
}
```

Again, the list is typically **not** sorted, for example by the zettel identifier.

The JSON object contains a key ''"list"'' where its value is a list of zettel JSON objects.
These zettel JSON objects themselves contains the keys ''"id"'' (value is a string containing the [[zettel identifier|00001006050000]]), ''"meta"'' (value as a JSON object), and ''"rights"'' (encodes the [[access rights|00001012921200]] for the given zettel).
The value of key ''"meta"'' effectively contains all metadata of the identified zettel, where metadata keys are encoded as JSON object keys and metadata values encoded as JSON strings.

The JSON objects keys ''"query"'' and ''"human"'' will be explained later in this manual.

id: 00001012051400
title: API: Query the list of all zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20220912111111
modified: 20230320151117
modified: 20230420160857

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'
# curl 'http://127.0.0.1:23123/z?q=title%3AAPI+ORDER+REVERSE+id+OFFSET+1'
00001012921000 API: JSON structure of an access token
00001012920500 Formats available by the API
00001012920000 Endpoints used by the API
...
```

If you want to retrieve a JSON document:

```sh
# curl 'http://127.0.0.1:23123/z?q=title%3AAPI&enc=json'
{"query":"title:API","human":"title HAS API","list":[{"id":"00001012921200","meta":{"back":"00001012051200 00001012051400 00001012053300 00001012053400 00001012053800 00001012053900 00001012054000","backward":"00001012051200 00001012051400 00001012053300 00001012053400 00001012053800 00001012053900 00001012054000","box-number":"1","created":"00010101000000","forward":"00001003000000 00001006020400 00001010000000 00001010040100 00001010040200 00001010070200 00001010070300","modified":"20220201171959","published":"20220201171959","role":"manual","syntax":"zmk","tags":"#api #manual #reference #zettelstore","title":"API: Encoding of Zettel Access Rights"},"rights":62},{"id":"00001012921000","meta":{"back":"00001012050600 00001012051200","backward":"00001012050200 00001012050400 00001012050600 00001012051200","box-number":"1","created":"00010101000000","forward":"00001012050200 00001012050400","published":"00010101000000","role":"manual","syntax":"zmk","tags":"#api #manual #reference #zettelstore","title":"API: JSON structure of an access token"},"rights":62}, ...]
# curl 'http://127.0.0.1:23123/z?q=title%3AAPI+ORDER+REVERSE+id+OFFSET+1&enc=json'
{"query":"title:API ORDER REVERSE id OFFSET 1","human":"title HAS API ORDER REVERSE id OFFSET 1","list":[{"id":"00001012921200","meta":{"back":"00001012051200 00001012051400 00001012053300 00001012053400 00001012053800 00001012053900 00001012054000","backward":"00001012051200 00001012051400 00001012053300 00001012053400 00001012053800 00001012053900 00001012054000","box-number":"1","created":"00010101000000","forward":"00001003000000 00001006020400 00001010000000 00001010040100 00001010040200 00001010070200 00001010070300","modified":"20220201171959","published":"20220201171959","role":"manual","syntax":"zmk","tags":"#api #manual #reference #zettelstore","title":"API: Encoding of Zettel Access Rights"},"rights":62},{"id":"00001012921000","meta":{"back":"00001012050600 00001012051200","backward":"00001012050200 00001012050400 00001012050600 00001012051200","box-number":"1","created":"00010101000000","forward":"00001012050200 00001012050400","published":"00010101000000","role":"manual","syntax":"zmk","tags":"#api #manual #reference #zettelstore","title":"API: JSON structure of an access token"},"rights":62}, ...]
```

The JSON object contains a key ''"list"'' where its value is a list of zettel JSON objects.
These zettel JSON objects themselves contains the keys ''"id"'' (value is a string containing the [[zettel identifier|00001006050000]]), ''"meta"'' (value as a JSON object), and ''"rights"'' (encodes the [[access rights|00001012921200]] for the given zettel).
The value of key ''"meta"'' effectively contains all metadata of the identified zettel, where metadata keys are encoded as JSON object keys and metadata values encoded as JSON strings.

Additionally, the JSON object contains the keys ''"query"'' and ''"human"'' with a string value.

```

The result is a text file.
The first word, separated by a horizontal tab (U+0009) contains the role name.
The rest of the line consists of zettel identifier, where the corresponding zettel have this role.
Zettel identifier are separated by a space character (U+0020).

Please note that the list is **not** sorted by the role name, so the same request might result in a different order.
If you want a sorted list, you could sort it on the command line (``curl 'http://127.0.0.1:23123/z?q=|role' | sort``) or within the software that made the call to the Zettelstore.

Of course, this list can be returned as a JSON object:
Of course, this list can also be returned as a JSON object:

```sh
# curl 'http://127.0.0.1:23123/z?q=|role?enc=json'
{"map":{"configuration":["00000000090002","00000000090000", ... ,"00000000000001"],"manual":["00001014000000", ... ,"00001000000000"],"zettel":["00010000000000", ... ,"00001012070500","00000000090001"]}}
```

The JSON object only contains the key ''"map"'' with the value of another object.

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: 20230109105303

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 [[Sexpr 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=sexpr''.
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 JSON object:
```sh
# curl 'http://127.0.0.1:23123/z/00001012053500?enc=sexpr'
# 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]].
In addition, you may provide a query parameter ''part=PART'' to select the relevant [[part|00001012920800]] of a zettel.
```sh

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=sexpr&parseonly'
# 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

id: 00001012053800
title: API: Retrieve context of an existing zettel
role: manual
tags: #api #manual #zettelstore
syntax: zmk
created: 20210222151131
modified: 20221208165112

The context of an origin zettel consists of those zettel that are somehow connected to the origin zettel.
Direct connections of an origin zettel to other zettel are visible via [[metadata values|00001006020000]], such as ''backward'', ''forward'' or other values with type [[identifier|00001006032000]] or [[set of identifier|00001006032500]].

The context is defined by a __direction__, a __cost__, and a __limit__:
* Direction: connections are directed.
  For example, the metadata value of ''backward'' lists all zettel that link to the current zettel, while ''forward'' list all zettel to which the current zettel links to.
  When you are only interested in one direction, set the parameter ''dir'' either to the value ""backward"" or ""forward"".
  All other values, including a missing value, is interpreted as ""both"".
* Cost: a normal direct connection has cost 5, an indirect connection is the length of the shortest path between two zettel.
  The cost of a folgezettel or a precursor zettel is just 1, the cost of successor zettel and predecessor zettel are 2.
  You should limit the cost by using the parameter ''cost''.
  Its default value is ""17"".
  A value of ""0"" does disable any cost check.
* Limit: to set an upper bound for the returned context, you should use the parameter ''limit''.
  Its default value is ""200"".
  A value of ""0"" disables does not limit the number of elements returned.

The search for the context of a zettel stops at the [[home zettel|00001004020000#home-zettel]].
This zettel is connected to all other zettel.
If it is included, the context would become too big and therefore unusable.

To retrieve the context of an existing zettel, use the [[endpoint|00001012920000]] ''/x/{ID}''[^Mnemonic: conte**X**t].

````
# curl 'http://127.0.0.1:23123/x/00001012053800?limit=3&dir=forward&cost=5'
{"id": "00001012053800","meta": {...},"rights":62,"list":[{"id": "00001012921000","meta": {...},"rights":62},{"id": "00001012920800","meta": {...},"rights":62},{"id": "00010000000000","meta": {...},"rights":62}]}
````
Formatted, this translates into:[^Metadata (key ''meta'') are hidden to make the overall structure easier to read.]
````json
{
  "id": "00001012053800",
  "meta": {...},
  "rights": 62,
  "list": [
    {
      "id": "00001012921000",
      "meta": {...},
      "rights":62
    },
    {
      "id": "00001012920800",
      "meta": {...},
      "rights":62
    },
    {
      "id": "00010000000000",
      "meta": {...},
      "rights":62
    }
  ]
}
````
=== Keys
The following top-level JSON keys are returned:
; ''id''
: The [[zettel identifier|00001006050000]] for which the context was requested.
; ''meta'':
: The metadata of the zettel, encoded as a JSON object.
; ''rights''
: An integer number that describes the [[access rights|00001012921200]] for the given zettel.
; ''list''
: A list of JSON objects with keys ''id'', ''meta'', and ''rights'' that contains the zettel of the context.

=== HTTP Status codes
; ''200''
: Retrieval was successful, the body contains an appropriate JSON object.
; ''400''
: Request was not valid.
; ''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: 00001012920000
title: Endpoints used by the API
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
created: 20210126175322
modified: 20221219162335
modified: 20230407125812

All API endpoints conform to the pattern ''[PREFIX]LETTER[/ZETTEL-ID]'', where:
; ''PREFIX''
: is the URL prefix (default: ""/""), configured via the ''url-prefix'' [[startup configuration|00001004010000]],
; ''LETTER''
: is a single letter that specifies the resource type,
; ''ZETTEL-ID''
: is an optional 14 digits string that uniquely [[identify a zettel|00001006050000]].

The following letters are currently in use:

|= Letter:| Without zettel identifier | With [[zettel identifier|00001006050000]] | Mnemonic
| ''a'' | POST: [[client authentication|00001012050200]] | | **A**uthenticate
|       | PUT: [[renew access token|00001012050400]] |
| ''o'' |  | GET: [[list zettel order|00001012054000]] | **O**rder
| ''u'' |  | GET [[unlinked references|00001012053900]] | **U**nlinked
| ''x'' | GET: [[retrieve administrative data|00001012070500]] | GET: [[list zettel context|00001012053800]] | Conte**x**t
| ''x'' | GET: [[retrieve administrative data|00001012070500]] | | E**x**ecute
|       | POST: [[execute command|00001012080100]]
| ''z'' | GET: [[list zettel|00001012051200]] | GET: [[retrieve zettel|00001012053300]] | **Z**ettel
|       | POST: [[create new zettel|00001012053200]] | PUT: [[update a zettel|00001012054200]]
|       |  | DELETE: [[delete zettel|00001012054600]]
|       |  | MOVE: [[rename zettel|00001012054400]]

The full URL will contain either the ""http"" oder ""https"" scheme, a host name, and an optional port number.

The API examples will assume the ""http"" schema, the local host ""127.0.0.1"", the default port ""23123"", and the default empty ''PREFIX'' ""/"".
Therefore, all URLs in the API documentation will begin with ""http://127.0.0.1:23123/"".

id: 00001012920500
title: Encodings available via the [[API|00001012000000]]
title: Encodings available via the API
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
created: 20210126175322
modified: 20230316180859
modified: 20230403123653

A zettel representation can be encoded in various formats for further processing.
These will be retrieved via the [[API|00001012000000]].

* [[html|00001012920510]]
* [[md|00001012920513]]
* [[sexpr|00001012920516]]
* [[shtml|00001012920525]]
* [[sz|00001012920516]]
* [[text|00001012920519]]
* [[zmk|00001012920522]]

id: 00001012920516
title: Sexpr Encoding
title: Sz Encoding
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
created: 20220422181104
modified: 20230316182622
modified: 20230403161458

A zettel representation that is a [[s-expression|https://en.wikipedia.org/wiki/S-expression]] (also known as symbolic expression).
A zettel representation that is a [[s-expression|00001012930000]] (also known as symbolic expression).

It is (relatively) easy to parse and contain all relevant information of a zettel, metadata and content.
For example, take a look at the Sexpr encoding of this page, which is available via the ""Info"" sub-page of this zettel: 
For example, take a look at the Sz encoding of this page, which is available via the ""Info"" sub-page of this zettel: 

* [[//z/00001012920516?enc=sexpr&part=zettel]],
* [[//z/00001012920516?enc=sexpr&part=meta]],
* [[//z/00001012920516?enc=sexpr&part=content]].
* [[//z/00001012920516?enc=sz&part=zettel]],
* [[//z/00001012920516?enc=sz&part=meta]],
* [[//z/00001012920516?enc=sz&part=content]].

If transferred via HTTP, the content type will be ''text/plain''.

Some zettel describe the [[Sz encoding|00001012931000]] in a more detailed way.
=== Syntax of s-expressions
There are only two types of elements: atoms and lists.

A list always starts with the left parenthesis (""''(''"", U+0028) and ends with a right parenthesis (""'')''"", U+0029).
A list may contain a possibly empty sequence of elements, i.e. lists and / or atoms.
Before the last element of a list of at least to elements, a full stop character (""''.''"", U+002E) signal a pair as the last two elements.
This allows a more space economic storage of data.

If transferred via HTTP, the content type will be ''text/plain''.
There are three syntactic forms for an atom: numbers, symbols and strings.

A number is a non-empty sequence of digits (""0"" ... ""9"").
The smallest number is ``0``, there are no negative numbers.

A symbol is a non-empty sequence of printable characters, except left or right parenthesis.
Unicode characters of the following categories contains printable characters in the above sense: letter (L), number (N), punctuation (P), symbol (S).
Symbols are case-insensitive, i.e. ""''ZETTEL''"" and ""''zettel''"" denote the same symbol.

A string starts with a quotation mark (""''"''"", U+0022), contains a possibly empty sequence of Unicode characters, and ends with a quotation mark.
To allow a string to contain a quotations mark, it must be prefixed by one backslash (""''\\''"", U+005C).
To allow a string to contain a backslash, it also must be prefixed by one backslash.
Unicode characters with a code less than U+FF are encoded by by the sequence ""''\\xNM''"", where ''NM'' is the hex encoding of the character.
Unicode characters with a code less than U+FFFF are encoded by by the sequence ""''\\uNMOP''"", where ''NMOP'' is the hex encoding of the character.
Unicode characters with a code less than U+FFFFFF are encoded by by the sequence ""''\\UNMOPQR''"", where ''NMOPQR'' is the hex encoding of the character.
In addition, the sequence ""''\\t''"" encodes a horizontal tab (U+0009), the sequence ""''\\n''"" encodes a line feed (U+000A).

Atoms are separated by Unicode characters of category separator (Z).

id: 00001012920525
title: SHTML Encoding
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
created: 20230316181044
modified: 20230316182614
modified: 20230403150657

A zettel representation that is a [[s-expression|https://en.wikipedia.org/wiki/S-expression]], syntactically similar to the [[Sexpr encoding|00001012920516]], but denotes [[HTML|00001012920510]] semantics.
A zettel representation that is a [[s-expression|00001012930000]], syntactically similar to the [[Sz encoding|00001012920516]], but denotes [[HTML|00001012920510]] semantics.
It is derived from a XML encoding in s-expressions, called [[SXML|https://en.wikipedia.org/wiki/SXML]].

It is (relatively) easy to parse and contains everything to transform it into real HTML.
In contrast to HTML, SHTML is easier to parse and to manipulate.
For example, take a look at the SHTML encoding of this page, which is available via the ""Info"" sub-page of this zettel: 

* [[//z/00001012920525?enc=shtml&part=zettel]],
* [[//z/00001012920525?enc=shtml&part=meta]],
* [[//z/00001012920525?enc=shtml&part=content]].

If transferred via HTTP, the content type will be ''text/plain''.

Internally, if a zettel should be transformed into HTML, the zettel is translated into the [[Sexpr encoding|00001012920516]], which is transformed into this SHTML encoding to produce the [[HTML encoding|00001012920510]].
Internally, if a zettel should be transformed into HTML, the zettel is translated into the [[Sz encoding|00001012920516]], which is transformed into this SHTML encoding to produce the [[HTML encoding|00001012920510]].

=== Syntax of SHTML
There are only two types of elements: atoms and lists, similar to the Sexpr encoding.
There are only two types of elements: atoms and lists, similar to the Sz encoding.

A list always starts with the left parenthesis (""''(''"", U+0028) and ends with a right parenthesis (""'')''"", U+0029).
A list may contain a possibly empty sequence of elements, i.e. lists and / or atoms.
Before the last element of a list of at least to elements, a full stop character (""''.''"", U+002E) signal a pair as the last two elements.
This allows a more space economic storage of data.

An HTML tag like ``< a href="link">Text</a>`` is encoded in SHTML with a list, where the first element is a symbol named a the tag.
The second element is an optional encoding of the tag's attributes.
Further elements are either other tag encodings or a string.
The above tag is encoded as ``(a (@ (href . "link")) "Text")``.
Also possible is to encode the attribute without pairs: ``(a (@ (href "link")) "Text")`` (note the missing full stop character).

id: 00001012921000
title: API: JSON structure of an access token
title: API: Structure of an access token
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
role: manual
created: 20210126175322
modified: 20230412155303

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 an JSON object, with the following named values:
The response is structured as a [[symbolic expression|00001012930000]] list, with the following elements:

|=Name|Description
|''access_token''|The access token itself, as string value, which is a [[JSON Web Token|https://tools.ietf.org/html/rfc7519]] (JWT, RFC 7915)
|''token_type''|The type of the token, always set to ''"Bearer"'', as described in [[RFC 6750|https://tools.ietf.org/html/rfc6750]]
|''expires_in''|An integer that gives a hint about the lifetime / endurance of the token, measured in seconds
# The type of the token, always set to ''"Bearer"'', as described in [[RFC 6750|https://tools.ietf.org/html/rfc6750]]
# The token itself, as string value, which is technically a [[JSON Web Token|https://tools.ietf.org/html/rfc7519]] (JWT, RFC 7915)
# An integer that gives a hint about the lifetime / endurance of the token, measured in seconds

id: 00001012930000
title: Symbolic Expression
role: manual
tags: #manual #reference #zettelstore
syntax: zmk
created: 20230403145644
modified: 20230403154010

A symbolic expression (also called __s-expression__) is a notation of a list-based tree.
Inner nodes are lists of arbitrary length, outer nodes are primitive values (also called __atoms__) or the empty list.

A symbolic expression is either
* a primitive value (__atom__), or
* a list of the form __(E,,1,, E,,2,, … E,,n,,)__, where __E,,i,,__ is itself a symbolic expression, separated by space characters.

An atom is a number, a string, or a symbol.

Symbolic expressions are used in programming languages like LISP or Scheme, where they denote both data structures and the program itself.
This allows a LISP or Scheme program to process LISP or Scheme programs.
That property is also used within Zettelstore.

Symbolic expressions are relatively easy to read, to parse, and to process.

=== See also
* [[Syntax|00001012930500]] of symbolic expressions in the Zettelstore
* [[S-expression @ Wikipedia|https://en.wikipedia.org/wiki/S-expression]]

id: 00001012930500
title: Syntax of Symbolic Expressions
role: manual
tags: #manual #reference #zettelstore
syntax: zmk
created: 20230403151127
modified: 20230403153609

=== Syntax of lists
A list always starts with the left parenthesis (""''(''"", U+0028) and ends with a right parenthesis (""'')''"", U+0029).
A list may contain a possibly empty sequence of elements, i.e. lists and / or atoms.

Internally, lists are composed of __cells__.
A cell allows to store two values.
The first value references the first element of a list.
The second value references the rest of the list, or is the special value __nil__ if there is no rest of the list.

However, it is possible to store an atom as the second value of the last cell.
In this case, before the last element of a list of at least two elements, a full stop character (""''.''"", U+002E) signals such a cell as the last two elements.
This allows a more space economic storage of data.

A __proper__ list, which contains __nil__ as the second value of the last element might be pictured as follows:

~~~draw
+---+---+   +---+---+         +---+---+
| V | N +-->| V | N +-->   -->| V |   |
+-+-+---+   +-+-+---+         +-+-+---+
  |           |                 |
  v           v                 v
+-------+   +-------+    +-------+
| Elem1 |   | Elem2 |    | ElemN |
+-------+   +-------+    +-------+
~~~

''V'' is a placeholder for a value, ''N'' is the reference to the next cell (also known as the rest / tail of the list).
Above list will be represented as an symbolic expression as ''(Elem1 Elem2 ... ElemN)''

An improper list will have a non-__nil__ reference to an atom as the very last element

~~~draw
+---+---+   +---+---+         +---+---+
| V | N +-->| V | N +-->   -->| V | V |
+-+-+---+   +-+-+---+         +-+-+-+-+
  |           |                 |   |
  v           v                 v   v
+-------+   +-------+    +-------+ +------+
| Elem1 |   | Elem2 |    | ElemN | | Atom |
+-------+   +-------+    +-------+ +------+
~~~

Above improper list will be represented as an symbolic expression as ''(Elem1 Elem2 ... ElemN . Atom)''


=== Syntax of numbers (atom)
A number is a non-empty sequence of digits (""0"" ... ""9"").
The smallest number is ``0``, there are no negative numbers.

=== Syntax of symbols (atom)
A symbol is a non-empty sequence of printable characters, except left or right parenthesis.
Unicode characters of the following categories contains printable characters in the above sense: letter (L), number (N), punctuation (P), symbol (S).
Symbols are case-sensitive, i.e. ""''ZETTEL''"" and ""''zettel''"" denote different symbols.

=== Syntax of string (atom)

A string starts with a quotation mark (""''"''"", U+0022), contains a possibly empty sequence of Unicode characters, and ends with a quotation mark.
To allow a string to contain a quotations mark, it must be prefixed by one backslash (""''\\''"", U+005C).
To allow a string to contain a backslash, it also must be prefixed by one backslash.
Unicode characters with a code less than U+FF are encoded by by the sequence ""''\\xNM''"", where ''NM'' is the hex encoding of the character.
Unicode characters with a code less than U+FFFF are encoded by by the sequence ""''\\uNMOP''"", where ''NMOP'' is the hex encoding of the character.
Unicode characters with a code less than U+FFFFFF are encoded by by the sequence ""''\\UNMOPQR''"", where ''NMOPQR'' is the hex encoding of the character.
In addition, the sequence ""''\\t''"" encodes a horizontal tab (U+0009), the sequence ""''\\n''"" encodes a line feed (U+000A).

=== See also
* Currently, Zettelstore uses [[Sxpf|https://codeberg.org/t73fde/sxpf]] (""Symbolic eXRression Framework"") to implement symbolic expression.
  The project page might contain additional information about the full syntax.

  Zettelstore only uses lists, numbers, string, and symbols to represent zettel.

id: 00001012931000
title: Encoding of Sz
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
created: 20230403153903
modified: 20230405133249

Zettel in a [[Sz encoding|00001012920516]] are represented as a [[symbolic expression|00001012930000]].
To process these symbolic expressions, you need to know, how a specific part of a zettel is represented by a symbolic expression.

Basically, each part of a zettel is represented as a list, often a nested list.
The first element of that list is always an unique symbol, which denotes that part.
The meaning / semantic of all other elements depend on that symbol.

=== Zettel
A full zettel is represented by a list of two elements.
The first elements represents the metadata, the second element represents the zettel content.

:::syntax
__Zettel__ **=** ''('' [[__Metadata__|#metadata]] [[__Content__|#content]] '')''.
:::

=== Metadata

Metadata is represented by a list, where the first element is the symbol ''META''.
Following elements represent each metadatum[^""Metadatum"" is used as the singular form of metadata.] of a zettel in standard order.

Standard order is: [[Title|00001006020000#title]], [[Role|00001006020000#role]], [[Tags|00001006020000#tags]], [[Syntax|00001006020000#syntax]], all other [[keys|00001006020000]] in alphabetic order.

:::syntax
__Metadata__ **=** ''(META'' [[__Metadatum__|00001012931200]] __Metadatum__ … __Metadatum__ '')''.
:::
=== Content

Zettel content is represented by a block.
:::syntax
__Content__ **=** [[__Block__|#block]].
:::

==== Block
A block is represented by a list with the symbol ''BLOCK'' as the first element.
All following elements represent a nested [[block-structured element|00001007030000]].

:::syntax
[!block|__Block__] **=** ''(BLOCK'' [[__BlockElement__|00001012931400]] __BlockElement__ … __BlockElement__ '')''.
:::

==== Inline
Both block-structured elements and some metadata values may contain [[inline-structured elements|00001007040000]].
Similar, inline-structured elements are represented as follows:

:::syntax
__Inline__ **=** ''(INLINE'' [[__InlineElement__|00001012931600]] __InlineElement__ … __InlineElement__ '')''.
:::

==== Attribute
[[Attributes|00001007050000]] may be specified for both block- and inline- structured elements.
Attributes are represented by the following schema.
Please note, the the symbol ''quote'' is lower-case by intention.

:::syntax
__Attribute__ **=** ''('' **[** ''quote'' ''('' [[__AttributeKeyValue__|00001012931800]] __AttributeKeyValue__ … __AttributeKeyValue__ '')'' **]** ')'.
:::

Either, there are no attributes.
These are specified by the empty list ''()''.
Or there are attributes.
In this case, the first element of the list must be the symbol ''quote'': ''(quote'' ''('' A,,1,, A,,2,, … A,,n,, '')'''')''.

=== Other
A list with ''UNKNOWN'' as its first element signals an internal error during transforming a zettel into the Sz encoding.
It may be ignored, or it may produce an error.

:::syntax
__Unknown__ **=** ''(UNKNOWN'' Object … '')''.
:::

The list may only contain the symbol ''UNKNOWN'', or additionally an unlimited amount of other objects.

Similar, any symbol with the pattern ''**xyz:NOT-FOUND**'', where ''xyz'' is any string, signals an internal error.

id: 00001012931200
title: Encoding of Sz Metadata
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
created: 20230403161618
modified: 20230405121932

A single metadata (""metadatum"") is represented by a triple: a symbol representing the type, a symbol representing the key, and either a string or a list that represent the value.

The key symbol must be ""quoted"", i.e. for the key ""title"": ''(quote title)''.
This property may be relaxed in future versions of the Zettelstore.

The symbol depends on the [[metadata key type|00001006030000]].
The value also depends somehow on the key type: a set of values is represented as a list, all other values are represented by a string, even if it is a number.

The following table maps key types to symbols and to the type of the value representation.

|=Key Type<| Symbol<| Value<
| [[Credential|00001006031000]] | ''CREDENTIAL'' | string
| [[EString|00001006031500]] | ''EMPTY-STRING'' | string
| [[Identifier|00001006032000]] | ''ZID'' | string
| [[IdentifierSet|00001006032500]] | ''ZID-SET'' | list
| [[Number|00001006033000]] | ''NUMBER'' | string
| [[String|00001006033500]] | ''STRING'' | string
| [[TagSet|00001006034000]] | ''TAG-SET'' | list
| [[Timestamp|00001006034500]] | ''TIMESTAMP'' | string
| [[URL|00001006035000]] | ''URL'' | string
| [[Word|00001006035500]] | ''WORD'' | string
| [[WordSet|00001006036000]] | ''WORD-SET'' | list
| [[Zettelmarkup|00001006036500]] | ''ZETTELMARKUP'' | string

If the value is represented as a list, its first element is the symbol ''list'', and all other elements are strings with the appropriate values.

:::syntax
__ListValue__ **=** ''(list'' String,,1,, String,,2,, &hellip; String,,n,, '')''.
:::

Examples:
* The title of this zettel is represented as: ''(EMPTY-STRING (quote title) "Encoding of Sz Metadata")''
* The tags of this zettel are represented as: ''(TAG-SET (quote tags) (list "#api" "#manual" "#reference" "#zettelstore"))''

id: 00001012931400
title: Encoding of Sz Block Elements
role: manual
tags: #api #manual #reference #zettelstore
syntax: zmk
created: 20230403161803
modified: 20230405132916

=== ''PARA''
:::syntax
__Paragraph__ **=** ''(PARA'' [[__InlineElement__|00001012931600]] … '')''.
:::
A paragraph is just a list of inline elements.

=== ''HEADING''
:::syntax
__Heading__ **=** ''(HEADING'' Number [[__Attributes__|00001012931000#attribute]] String,,1,, String,,2,, [[__InlineElement__|00001012931600]] … '')''.
:::
A heading consists of a number, which specifies its level (1 -- 5), its optional attributes.
The first string is a ""slug"" of the heading text, i.e. transformed it to lower case, replaced space character with minus sign, and some more.
The second string is the slug, but made unique for the whole zettel.
Then the heading text follows as a sequence of inline elements.

=== ''THEMATIC''
:::syntax
__Thematic__ **=** ''(THEMATIC'' [[__Attributes__|00001012931000#attribute]] '')''.
:::

=== ''ORDERED'', ''UNORDERED'', ''QUOTATION''
These three symbols are specifying different kinds of lists / enumerations: an ordered list, an unordered list, and a quotation list.
Their structure is the same.

:::syntax
__OrderedList__ **=** ''(ORDERED'' __ListElement__ … '')''.

__UnorderedList__ **=** ''(UNORDERED'' __ListElement__ … '')''.

__QuotationList__ **=** ''(QUOTATION'' __ListElement__ … '')''.
:::

:::syntax
__ListElement__ **=** [[__Block__|00001012931000#block]] **|** [[__Inline__|00001012931000#inline]].
:::
A list element is either a block or an inline.
If it is a block, it may contain a nested list.
=== ''DESCRIPTION''
:::syntax
__Description__ **=** ''(DESCRIPTION'' __DescriptionTerm__ __DescriptionValues__ __DescriptionTerm__ __DescriptionValues__ … '')''.
:::
A description is a sequence of one ore more terms and values.

:::syntax
__DescriptionTerm__ **=** [[__Inline__|00001012931000#inline]].
:::
A description term is just an inline-structured value.

:::syntax
__DescriptionValues__ **=** ''(BLOCK'' [[__Block__|00001012931000#block]] … '')''.
:::
Description values are sequences of blocks.

=== ''TABLE''
:::syntax
__Table__ **=** ''(TABLE'' __TableHeader__ __TableRow__ … '')''.
:::
A table is a table header and a sequence of table rows.

:::syntax
__TableHeader__ **=** ''()'' **|** ''(list'' __TableCell__ … '')''.
:::
A table header is either the empty list or a list of table cells stating with the ''list'' symbol.

:::syntax
__TableRow__ **=** ''(list'' __TableCell__ … '')''.
:::
A table row is a list with the initial symbol ''list'', followed by table cells.

=== ''CELL'', ''CELL-*''
There are four kinds of table cells, one for each possible cell alignment.
The structure is the same for all kind.

:::syntax
__TableCell__ **=** __DefaultCell__ **|** __CenterCell__ **|** __LeftCell__ **|** __RightCell__.
:::

:::syntax
__DefaultCell__ **=** ''(CELL'' [[__InlineElement__|00001012931600]] … '')''.
:::
The cell content, specified by the sequence of inline elements, used the default alignment.

:::syntax
__CenterCell__ **=** ''(CELL-CENTER'' [[__InlineElement__|00001012931600]] … '')''.
:::
The cell content, specified by the sequence of inline elements, is centered aligned.

:::syntax
__LeftCell__ **=** ''(CELL-LEFT'' [[__InlineElement__|00001012931600]] … '')''.
:::
The cell content, specified by the sequence of inline elements, is left aligned.

:::syntax
__RightCell__ **=** ''(CELL-RIGHT'' [[__InlineElement__|00001012931600]] … '')''.
:::
The cell content, specified by the sequence of inline elements, is right aligned.

=== ''REGION-*''
The following lists specifies different kinds of regions.
A region treat a sequence of block elements to be belonging together in certain ways.
The have a similar structure.

:::syntax
__BlockRegion__ **=** ''(REGION-BLOCK'' [[__Attributes__|00001012931000#attribute]] [[__Block__|00001012931000#block]] [[__Inline__|00001012931000#inline]] '')''.
:::
A block region just treats the block to belong in an unspecified way.
Typically, the reason is given in the attributes.
The inline describes the block.

:::syntax
__QuoteRegion__ **=** ''(REGION-QUOTE'' [[__Attributes__|00001012931000#attribute]] [[__Block__|00001012931000#block]] [[__Inline__|00001012931000#inline]] '')''.
:::
A block region just treats the block to contain a longer quotation.
Attributes may further specify the quotation.
The inline typically describes author / source of the quotation.

:::syntax
__VerseRegion__ **=** ''(REGION-VERSE'' [[__Attributes__|00001012931000#attribute]] [[__Block__|00001012931000#block]] [[__Inline__|00001012931000#inline]] '')''.
:::
A block region just treats the block to contain a verse.
Soft line break are transformed into hard line breaks to save the structure of the verse / poem.
Attributes may further specify something.
The inline typically describes author / source of the verse.

=== ''VERBATIM-*''
The following lists specifies some literal text of more than one line.
The structure is always the same, the initial symbol denotes the actual usage.
The content is encoded as a string, most likely to contain control characters that signals the end of a line.

:::syntax
__CommentVerbatim__ **=** ''(VERBATIM-COMMENT'' [[__Attributes__|00001012931000#attribute]] String '')''.
:::
The string contains text that should be treated as an internal comment not to be interpreted further.

:::syntax
__EvalVerbatim__ **=** ''(VERBATIM-EVAL'' [[__Attributes__|00001012931000#attribute]] String '')''.
:::
The string contains text that should be evaluated by an (external) software to produce some derived content.

:::syntax
__HTMLVerbatim__ **=** ''(VERBATIM-HTML'' [[__Attributes__|00001012931000#attribute]] String '')''.
:::
The string contains HTML code.

:::syntax
__MathVerbatim__ **=** ''(VERBATIM-MATH'' [[__Attributes__|00001012931000#attribute]] String '')''.
:::
The string contains text that should be treated as special code to be interpreted as mathematical formulas.

:::syntax
__CodeVerbatim__ **=** ''(VERBATIM-CODE'' [[__Attributes__|00001012931000#attribute]] String '')''.
:::
The string contains text that should be treated as (executable) code.

:::syntax
__ZettelVerbatim__ **=** ''(VERBATIM-ZETTEL'' [[__Attributes__|00001012931000#attribute]] String '')''.
:::
The string contains text that should be treated as (nested) zettel content.

=== ''BLOB''
:::syntax
__BLOB__ **=** ''(BLOB'' [[__Inline__|00001012931000#inline]] String,,1,, String,,2,, '')''.
:::
A BLOB contains an image in block mode.
The inline states some description.
The first string contains the syntax of the image.
The second string contains the actual image.
If the syntax is ""SVG"", then the second string contains the SVG code.
Otherwise the (binary) image data is encoded with base64.

=== ''TRANSCLUDE''
:::syntax
__Transclude__ **=** ''(TRANSCLUDE'' [[__Attributes__|00001012931000#attribute]] [[__Reference__|00001012931900]] '')''.
:::
A transclude list only occurs for a parsed zettel, but not for a evaluated zettel.
Evaluating a zettel also means that all transclusions are resolved.

__Reference__ denotes the zettel to be transcluded.