if ch < '0' || '9' < ch {
			return false
		}
	}
	return true
}

// ZettelMeta is a map containg the metadata of a zettel.
// ZettelMeta is a map containg the normalized metadata of a zettel.
type ZettelMeta map[string]string

// ZettelRights is an integer that encode access rights for a zettel.
type ZettelRights uint8

// Values for ZettelRights, can be or-ed
const (
	ZettelCanNone   ZettelRights = 1 << iota
	ZettelCanCreate              // Current user is allowed to create a new zettel
	ZettelCanRead                // Requesting user is allowed to read the zettel
	ZettelCanWrite               // Requesting user is allowed to update the zettel
	ZettelCanRename              // Requesting user is allowed to provide the zettel with a new identifier
	placeholdergo1               // Was assigned to rename right, which is now removed
	ZettelCanDelete              // Requesting user is allowed to delete the zettel
	ZettelMaxRight               // Sentinel value
)

// MetaRights contains the metadata of a zettel, and its rights.
type MetaRights struct {
	Meta   ZettelMeta
	Rights ZettelRights
}

// ZidMetaRights contains the identifier, the metadata of a zettel, and its rights.
type ZidMetaRights struct {
	ID     ZettelID
	Meta   ZettelMeta
	Rights ZettelRights
}

// ZettelData contains all data for a zettel.
//
//   - Meta is a map containing the metadata of the zettel.
//   - Rights is an integer specifying the access rights.
//   - Encoding is a string specifying the encoding of the zettel content.
//   - Content is the zettel content itself.
type ZettelData struct {
	Meta     ZettelMeta
	Rights   ZettelRights
	Encoding string
	Content  string
	Content  string // raw, uninterpreted zettel content
}

// Aggregate maps metadata keys to list of zettel identifier.
type Aggregate map[string][]ZettelID

// SPDX-FileCopyrightText: 2021-present Detlef Stern
//-----------------------------------------------------------------------------

package api

import "fmt"

// Predefined Zettel Identifier
// Predefined zettel identifier.
//
// See [List of predefined zettel].
//
// [List of predefined zettel]: https://zettelstore.de/manual/h/00001005090000
const (
	// System zettel
	ZidVersion              = ZettelID("00000000000001") // -> 0001
	ZidHost                 = ZettelID("00000000000002") // -> 0002
	ZidOperatingSystem      = ZettelID("00000000000003") // -> 0003
	ZidLicense              = ZettelID("00000000000004") // -> 0004
	ZidAuthors              = ZettelID("00000000000005") // -> 0005
	ZidDependencies         = ZettelID("00000000000006") // -> 0006
	ZidLog                  = ZettelID("00000000000007") // -> 0007
	ZidMemory               = ZettelID("00000000000008") // -> 0008
	ZidSx                   = ZettelID("00000000000009") // -> 0009
	ZidHTTP                 = ZettelID("00000000000010") // -> 000a
	ZidAPI                  = ZettelID("00000000000011") // -> 000b
	ZidWebUI                = ZettelID("00000000000012") // -> 000c
	ZidConsole              = ZettelID("00000000000013") // -> 000d
	ZidBoxManager           = ZettelID("00000000000020") // -> 000e
	ZidZettel               = ZettelID("00000000000021") // -> 000f
	ZidIndex                = ZettelID("00000000000022") // -> 000g
	ZidQuery                = ZettelID("00000000000023") // -> 000h
	ZidMetadataKey          = ZettelID("00000000000090") // -> 000i
	ZidParser               = ZettelID("00000000000092") // -> 000j
	ZidStartupConfiguration = ZettelID("00000000000096") // -> 000k
	ZidConfiguration        = ZettelID("00000000000100") // -> 000l
	ZidDirectory            = ZettelID("00000000000101") // -> 000m
	ZidVersion              = ZettelID("00000000000001")
	ZidHost                 = ZettelID("00000000000002")
	ZidOperatingSystem      = ZettelID("00000000000003")
	ZidLicense              = ZettelID("00000000000004")
	ZidAuthors              = ZettelID("00000000000005")
	ZidDependencies         = ZettelID("00000000000006")
	ZidLog                  = ZettelID("00000000000007")
	ZidMemory               = ZettelID("00000000000008")
	ZidSx                   = ZettelID("00000000000009")
	ZidHTTP                 = ZettelID("00000000000010")
	ZidAPI                  = ZettelID("00000000000011")
	ZidWebUI                = ZettelID("00000000000012")
	ZidConsole              = ZettelID("00000000000013")
	ZidBoxManager           = ZettelID("00000000000020")
	ZidZettel               = ZettelID("00000000000021")
	ZidIndex                = ZettelID("00000000000022")
	ZidQuery                = ZettelID("00000000000023")
	ZidMetadataKey          = ZettelID("00000000000090")
	ZidParser               = ZettelID("00000000000092")
	ZidStartupConfiguration = ZettelID("00000000000096")
	ZidConfiguration        = ZettelID("00000000000100")
	ZidDirectory            = ZettelID("00000000000101")
	ZidWarnings             = ZettelID("00000000000102") // -> 000n

	// WebUI HTML templates are in the range 10000..19999
	ZidBaseTemplate   = ZettelID("00000000010100") // -> 000s
	ZidLoginTemplate  = ZettelID("00000000010200") // -> 000t
	ZidListTemplate   = ZettelID("00000000010300") // -> 000u
	ZidZettelTemplate = ZettelID("00000000010401") // -> 000v
	ZidInfoTemplate   = ZettelID("00000000010402") // -> 000w
	ZidFormTemplate   = ZettelID("00000000010403") // -> 000x
	ZidBaseTemplate   = ZettelID("00000000010100")
	ZidLoginTemplate  = ZettelID("00000000010200")
	ZidListTemplate   = ZettelID("00000000010300")
	ZidZettelTemplate = ZettelID("00000000010401")
	ZidInfoTemplate   = ZettelID("00000000010402")
	ZidFormTemplate   = ZettelID("00000000010403")
	ZidRenameTemplate = ZettelID("00000000010404") // -> 001z
	ZidDeleteTemplate = ZettelID("00000000010405") // -> 000y
	ZidErrorTemplate  = ZettelID("00000000010700") // -> 000z
	ZidDeleteTemplate = ZettelID("00000000010405")
	ZidErrorTemplate  = ZettelID("00000000010700")

	// WebUI sxn code zettel are in the range 19000..19999
	ZidSxnStart = ZettelID("00000000019000") // -> 000q
	ZidSxnBase  = ZettelID("00000000019990") // -> 000r
	ZidSxnStart = ZettelID("00000000019000")
	ZidSxnBase  = ZettelID("00000000019990")

	// CSS-related zettel are in the range 20000..29999
	ZidBaseCSS = ZettelID("00000000020001") // -> 0010
	ZidUserCSS = ZettelID("00000000025001") // -> 0011
	ZidBaseCSS = ZettelID("00000000020001")
	ZidUserCSS = ZettelID("00000000025001")

	// WebUI JS zettel are in the range 30000..39999

	// WebUI image zettel are in the range 40000..49999
	ZidEmoji = ZettelID("00000000040001") // -> 000o
	ZidEmoji = ZettelID("00000000040001")

	// Other sxn code zettel are in the range 50000..59999
	ZidSxnPrelude = ZettelID("00000000059900") // -> 000p
	ZidSxnPrelude = ZettelID("00000000059900")

	// Predefined Zettelmarkup zettel are in the range 60000..69999
	ZidRoleZettelZettel        = ZettelID("00000000060010") // -> 0012
	ZidRoleConfigurationZettel = ZettelID("00000000060020") // -> 0013
	ZidRoleRoleZettel          = ZettelID("00000000060030") // -> 0014
	ZidRoleTagZettel           = ZettelID("00000000060040") // -> 0015
	ZidRoleZettelZettel        = ZettelID("00000000060010")
	ZidRoleConfigurationZettel = ZettelID("00000000060020")
	ZidRoleRoleZettel          = ZettelID("00000000060030")
	ZidRoleTagZettel           = ZettelID("00000000060040")

	// Range 90000...99999 is reserved for zettel templates
	ZidTOCNewTemplate    = ZettelID("00000000090000") // -> 0016
	ZidTemplateNewZettel = ZettelID("00000000090001") // -> 0017
	ZidTemplateNewRole   = ZettelID("00000000090004") // -> 001a
	ZidTemplateNewTag    = ZettelID("00000000090003") // -> 0019
	ZidTemplateNewUser   = ZettelID("00000000090002") // -> 0018
	ZidTOCNewTemplate    = ZettelID("00000000090000")
	ZidTemplateNewZettel = ZettelID("00000000090001")
	ZidTemplateNewRole   = ZettelID("00000000090004")
	ZidTemplateNewTag    = ZettelID("00000000090003")
	ZidTemplateNewUser   = ZettelID("00000000090002")

	ZidSession      = ZettelID("00009999999997") // -> 00zx
	ZidAppDirectory = ZettelID("00009999999998") // -> 00zy
	ZidMapping      = ZettelID("00009999999999") // -> 00zz
	ZidDefaultHome  = ZettelID("00010000000000") // -> 0100
	// Range 00000999999900...00000999999999 are predefined zettel to be searched by content.
	ZidAppDirectory = ZettelID("00000999999999")

	// Default Home Zettel
	ZidDefaultHome = ZettelID("00010000000000")
)

// LengthZid factors the constant length of a zettel identifier
const LengthZid = len(ZidDefaultHome)

// Values of the metadata key/value type.
// Values of the metadata key/value types.
//
// See [Supported Key Types].
//
// [Supported Key Types]: https://zettelstore.de/manual/h/00001006030000
const (
	MetaCredential   = "Credential"
	MetaEmpty        = "EString"
	MetaID           = "Identifier"
	MetaIDSet        = "IdentifierSet"
	MetaNumber       = "Number"
	MetaString       = "String"
	MetaTagSet       = "TagSet"
	MetaTimestamp    = "Timestamp"
	MetaURL          = "URL"
	MetaWord         = "Word"
	MetaZettelmarkup = "Zettelmarkup"
)

// Predefined general Metadata keys
// Predefined / supported metadata keys.
//
// See [Supported Metadata Keys].
//
// [Supported Metadata Keys]: https://zettelstore.de/manual/h/00001006020000
const (
	KeyID           = "id"
	KeyTitle        = "title"
	KeyRole         = "role"
	KeyTags         = "tags"
	KeySyntax       = "syntax"
	KeyAuthor       = "author"

	KeyFolgeRole    = "folge-role"
	KeyForward      = "forward"
	KeyLang         = "lang"
	KeyLicense      = "license"
	KeyModified     = "modified"
	KeyPrecursor    = "precursor"
	KeyPredecessor  = "predecessor"
	KeyPrequel      = "prequel"
	KeyPublished    = "published"
	KeyQuery        = "query"
	KeyReadOnly     = "read-only"
	KeySequel       = "sequel"
	KeySubordinates = "subordinates"
	KeySuccessors   = "successors"
	KeySuperior     = "superior"
	KeySummary      = "summary"
	KeySuperior     = "superior"
	KeyURL          = "url"
	KeyUselessFiles = "useless-files"
	KeyUserID       = "user-id"
	KeyUserRole     = "user-role"
	KeyVisibility   = "visibility"
)

// Predefined Metadata values
// Predefined metadata values.
const (
	ValueFalse             = "false"
	ValueTrue              = "true"
	ValueLangEN            = "en"
	ValueRoleConfiguration = "configuration"
	ValueRoleTag           = "tag"
	ValueRoleRole          = "role"
	ValueRoleZettel        = "zettel"
	ValueSyntaxCSS         = "css"
	ValueSyntaxDraw        = "draw"
	ValueSyntaxGif         = "gif"
	ValueSyntaxHTML        = "html"
	ValueSyntaxMarkdown    = "markdown"
	ValueSyntaxMD          = "md"
	ValueSyntaxNone        = "none"
	ValueSyntaxSVG         = "svg"
	ValueSyntaxSxn         = "sxn"
	ValueSyntaxText        = "text"
	ValueSyntaxZmk         = "zmk"
	ValueLangEN            = "en"            // Default for "lang"
	ValueRoleConfiguration = "configuration" // A role for internal zettel
	ValueRoleTag           = "tag"           // A role for tag zettel
	ValueRoleRole          = "role"          // A role for role zettel
	ValueRoleZettel        = "zettel"        // A role for zettel
	ValueSyntaxCSS         = "css"           // Syntax: CSS
	ValueSyntaxDraw        = "draw"          // Syntax: Drawing
	ValueSyntaxGif         = "gif"           // Syntax GIF image
	ValueSyntaxHTML        = "html"          // Syntax: HTML
	ValueSyntaxMarkdown    = "markdown"      // Syntax: Markdown / CommonMark
	ValueSyntaxMD          = "md"            // Syntax: Markdown / CommonMark
	ValueSyntaxNone        = "none"          // Syntax: no syntax / content, just metadata
	ValueSyntaxSVG         = "svg"           // Syntax: SVG
	ValueSyntaxSxn         = "sxn"           // Syntax: S-Expression
	ValueSyntaxText        = "text"          // Syntax: plain text
	ValueSyntaxZmk         = "zmk"           // Syntax: Zettelmarkup
	ValueUserRoleCreator   = "creator"
	ValueUserRoleOwner     = "owner"
	ValueUserRoleReader    = "reader"
	ValueUserRoleWriter    = "writer"
	ValueVisibilityCreator = "creator"
	ValueVisibilityExpert  = "expert"
	ValueVisibilityLogin   = "login"
	ValueVisibilityOwner   = "owner"
	ValueVisibilityPublic  = "public"
)

// Additional HTTP constants.
const (
	MethodMove = "MOVE" // HTTP method for renaming a zettel

	HeaderAccept      = "Accept"
	HeaderContentType = "Content-Type"
	HeaderDestination = "Destination"
	HeaderLocation    = "Location"
)

// Values for HTTP query parameter.

	QueryKeyRole      = "role"
	QueryKeySeed      = "_seed"
	QueryKeyTag       = "tag"
)

// Supported encoding values.
const (
	EncodingHTML  = "html"
	EncodingMD    = "md"
	EncodingSHTML = "shtml"
	EncodingSz    = "sz"
	EncodingText  = "text"
	EncodingZMK   = "zmk"
	EncodingHTML  = "html"  // Plain HTML
	EncodingMD    = "md"    // Markdown
	EncodingSHTML = "shtml" // SxHTML
	EncodingSz    = "sz"    // Structure of zettel, encoded a an S-expression
	EncodingText  = "text"  // plain text content
	EncodingZMK   = "zmk"   // Zettelmarkup

	EncodingPlain = "plain"
	EncodingData  = "data"
	EncodingPlain = "plain" // Plain zettel, no processing
	EncodingData  = "data"  // Plain zettel, metadata as S-Expression
)

var mapEncodingEnum = map[string]EncodingEnum{
	EncodingHTML:  EncoderHTML,
	EncodingMD:    EncoderMD,
	EncodingSHTML: EncoderSHTML,
	EncodingSz:    EncoderSz,

	PartContent = "content"
	PartZettel  = "zettel"
)

// Command to be executed atthe Zettelstore
type Command string

// Supported command values
// Supported command values.
const (
	CommandAuthenticated = Command("authenticated")
	CommandRefresh       = Command("refresh")
)

// Supported search operator representations
// Supported search operator representations.
const (
	BackwardDirective = "BACKWARD"
	ContextDirective  = "CONTEXT"
	CostDirective     = "COST"
	ForwardDirective  = "FORWARD"
	FullDirective     = "FULL"
	IdentDirective    = "IDENT"
	ItemsDirective    = "ITEMS"
	MaxDirective      = "MAX"
	LimitDirective    = "LIMIT"
	OffsetDirective   = "OFFSET"
	OrDirective       = "OR"
	OrderDirective    = "ORDER"
	PhraseDirective   = "PHRASE"
	PickDirective     = "PICK"
	RandomDirective   = "RANDOM"
	ReverseDirective  = "REVERSE"
	UnlinkedDirective = "UNLINKED"
	BackwardDirective = "BACKWARD" // Backward-only context
	ContextDirective  = "CONTEXT"  // Context directive
	CostDirective     = "COST"     // Maximum cost of a context operation
	ForwardDirective  = "FORWARD"  // Forward-only context
	FullDirective     = "FULL"     // Include tags in context
	IdentDirective    = "IDENT"    // Use only specified zettel
	ItemsDirective    = "ITEMS"    // Select list elements in a zettel
	MaxDirective      = "MAX"      // Maximum number of context results
	LimitDirective    = "LIMIT"    // Maximum number of zettel
	OffsetDirective   = "OFFSET"   // Offset to start returned zettel list
	OrDirective       = "OR"       // Combine several search expression with an "or"
	OrderDirective    = "ORDER"    // Specify metadata keys for the order of returned list
	PhraseDirective   = "PHRASE"   // Only unlinked zettel with given phrase
	PickDirective     = "PICK"     // Pick some random zettel
	RandomDirective   = "RANDOM"   // Order zettel list randomly
	ReverseDirective  = "REVERSE"  // Reverse the order of a zettel list
	UnlinkedDirective = "UNLINKED" // Search for zettel that contain a phase(s) but do not link

	ActionSeparator = "|"
	ActionSeparator = "|" // Separates action list of previous elements of query expression

	AtomAction     = "ATOM"
	KeysAction     = "KEYS"
	MinAction      = "MIN"
	MaxAction      = "MAX"
	NumberedAction = "NUMBERED"
	RedirectAction = "REDIRECT"
	ReIndexAction  = "REINDEX"
	RSSAction      = "RSS"
	TitleAction    = "TITLE"
	AtomAction     = "ATOM"     // Return an Atom web feed
	KeysAction     = "KEYS"     // Provide metadata key used
	MinAction      = "MIN"      // Return only those values with a minimum amount of zettel
	MaxAction      = "MAX"      // Return only those values with a maximum amount of zettel
	NumberedAction = "NUMBERED" // Return a numbered list
	RedirectAction = "REDIRECT" // Return the first zettel in list
	ReIndexAction  = "REINDEX"  // Ensure that zettel is/are indexed.
	RSSAction      = "RSS"      // Return a RSS web feed
	TitleAction    = "TITLE"    // Set a title for Atom or RSS web feed

	ExistOperator    = "?"
	ExistNotOperator = "!?"
	ExistOperator    = "?"  // Does zettel have metadata with given key?
	ExistNotOperator = "!?" // True id zettel does not have metadata with given key.

	SearchOperatorNot        = "!"
	SearchOperatorEqual      = "="
	SearchOperatorNotEqual   = "!="
	SearchOperatorHas        = ":"
	SearchOperatorHasNot     = "!:"
	SearchOperatorPrefix     = "["
	SearchOperatorNoPrefix   = "!["
	SearchOperatorSuffix     = "]"
	SearchOperatorNoSuffix   = "!]"
	SearchOperatorMatch      = "~"
	SearchOperatorNoMatch    = "!~"
	SearchOperatorLess       = "<"
	SearchOperatorNotLess    = "!<"
	SearchOperatorGreater    = ">"
	SearchOperatorNotGreater = "!>"
	SearchOperatorEqual      = "="  // True if values are equal
	SearchOperatorNotEqual   = "!=" // False if values are equal
	SearchOperatorHas        = ":"  // True if values are equal/included
	SearchOperatorHasNot     = "!:" // False if values are equal/included
	SearchOperatorPrefix     = "["  // True if value is prefix of the other
	SearchOperatorNoPrefix   = "![" // False if value is prefix of the other
	SearchOperatorSuffix     = "]"  // True if value is suffix of other
	SearchOperatorNoSuffix   = "!]" // False if value is suffix of other
	SearchOperatorMatch      = "~"  // True if value is included in other
	SearchOperatorNoMatch    = "!~" // False if value is included in other
	SearchOperatorLess       = "<"  // True if value is smaller than other
	SearchOperatorNotLess    = "!<" // False if value is smaller than other
	SearchOperatorGreater    = ">"  // True if value is greater than other
	SearchOperatorNotGreater = "!>" // False if value is greater than other
)

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

	result := URLBuilder{prefix: prefix}
	if key != '/' {
		result.base.AddPath(string([]byte{key}))
	}
	return &result
}

// Clone an URLBuilder
// Clone an URLBuilder.
func (ub *URLBuilder) Clone() *URLBuilder {
	cpy := new(URLBuilder)
	ub.base.Copy(&cpy.base)
	cpy.prefix = ub.prefix
	return cpy
}

// SetZid sets the zettel identifier.
func (ub *URLBuilder) SetZid(zid ZettelID) *URLBuilder {
	ub.base.AddPath(string(zid))
	return ub
}

// AppendPath adds a new path element
// AppendPath adds a new path element.
func (ub *URLBuilder) AppendPath(p string) *URLBuilder {
	ub.base.AddPath(p)
	return ub
}

// AppendKVQuery adds a new key/value query parameter
// AppendKVQuery adds a new key/value query parameter.
func (ub *URLBuilder) AppendKVQuery(key, value string) *URLBuilder {
	ub.base.AddQuery(key, value)
	return ub
}

// AppendQuery adds a new query
// AppendQuery adds a new query.
//
// Basically the same as [URLBuilder.AppendKVQuery]([api.QueryKeyQuery], value)
func (ub *URLBuilder) AppendQuery(value string) *URLBuilder {
	if value != "" {
		ub.base.AddQuery(QueryKeyQuery, value)
	}
	return ub
}

// ClearQuery removes all query parameters.
func (ub *URLBuilder) ClearQuery() *URLBuilder {
	ub.base.RemoveQueries()
	return ub
}

// SetFragment stores the fragment
// SetFragment sets the fragment.
func (ub *URLBuilder) SetFragment(s string) *URLBuilder {
	ub.base.SetFragment(s)
	return ub
}

// String produces a string value.
func (ub *URLBuilder) String() string {

// SPDX-FileCopyrightText: 2020-present Detlef Stern
//-----------------------------------------------------------------------------

// Package attrs stores attributes of zettel parts.
package attrs

import (
	"slices"
	"strings"

	"t73f.de/r/zsc/maps"
)

// Attributes store additional information about some node types.
type Attributes map[string]string

func (a Attributes) Remove(key string) Attributes {
	if a != nil {
		delete(a, key)
	}
	return a
}

// AddClass adds a value to the class attribute.
func (a Attributes) AddClass(class string) Attributes {
// Add a value to an attribute key.
func (a Attributes) Add(key, value string) Attributes {
	if a == nil {
		return map[string]string{"class": class}
		return map[string]string{key: value}
	}
	classes := a.GetClasses()
	for _, cls := range classes {
		if cls == class {
			return a
		}
	}
	values := a.Values(key)
	if !slices.Contains(values, value) {
		values = append(values, value)
		a[key] = strings.Join(values, " ")
	}
	return a
}

	classes = append(classes, class)
	a["class"] = strings.Join(classes, " ")
	return a
}

// Values are the space separated values of an attribute.
func (a Attributes) Values(key string) []string {
	if a != nil {
		if value, ok := a[key]; ok {
			return strings.Fields(value)
		}
	}
// GetClasses returns the class values as a string slice
func (a Attributes) GetClasses() []string {
	if a == nil {
		return nil
	}
	return nil
}
	classes, ok := a["class"]
	if !ok {
		return nil
	}
	return strings.Fields(classes)

// Has the attribute key a value?
func (a Attributes) Has(key, value string) bool {
	return slices.Contains(a.Values(key), value)
}

// HasClass returns true, if attributes contains the given class.
func (a Attributes) HasClass(s string) bool {
// AddClass adds a value to the class attribute.
func (a Attributes) AddClass(class string) Attributes { return a.Add("class", class) }
	if a == nil {
		return false
	}
	classes, found := a["class"]

// GetClasses returns the class values as a string slice
	if !found {
		return false
	}
	return strings.Contains(" "+classes+" ", " "+s+" ")
func (a Attributes) GetClasses() []string { return a.Values("class") }

// HasClass returns true, if attributes contains the given class.
}
func (a Attributes) HasClass(s string) bool { return a.Has("class", s) }

func TestHasClass(t *testing.T) {
	t.Parallel()
	testcases := []struct {
		classes string
		class   string
		exp     bool
	}{
		{"", "", true},
		{"", "", false},
		{"x", "", false},
		{"x", "x", true},
		{"x", "y", false},
		{"abc def ghi", "abc", true},
		{"abc def ghi", "def", true},
		{"abc def ghi", "ghi", true},
		{"ab de gi", "b", false},

// SPDX-FileCopyrightText: 2021-present Detlef Stern
//-----------------------------------------------------------------------------

// Package client provides a client for accessing the Zettelstore via its API.
package client

import (
	"bufio"
	"bytes"
	"context"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"t73f.de/r/sx"
	"t73f.de/r/sx/sxreader"
	"t73f.de/r/zsc/api"
	"t73f.de/r/zsc/sexp"
	"t73f.de/r/zsc/sz"
)

// Client contains all data to execute requests.
type Client struct {
	base      string
	username  string
	password  string
	token     string
	tokenType string
	expires   time.Time
	client    http.Client
}

// Base returns the base part of the URLs that are used to communicate with a Zettelstore.
func (c *Client) Base() string { return c.base }

// NewClient create a new client.
// NewClient creates a new client with a given base URL to a Zettelstore.
func NewClient(u *url.URL) *Client {
	myURL := *u
	myURL.User = nil
	myURL.ForceQuery = false
	myURL.RawQuery = ""
	myURL.Fragment = ""
	myURL.RawFragment = ""

			},
		},
	}
	return &c
}

// AllowRedirect will modify the client to not follow redirect status code when
// using the Zettelstore. The original behaviour can be restored by settinh
// "allow" to false.
// using the Zettelstore. The original behaviour can be restored by setting
// allow to false.
func (c *Client) AllowRedirect(allow bool) {
	if allow {
		c.client.CheckRedirect = func(req *http.Request, via []*http.Request) error {
		c.client.CheckRedirect = func(*http.Request, []*http.Request) error {
			return http.ErrUseLastResponse
		}
	} else {
		c.client.CheckRedirect = nil
	}
}

// Error encapsulates the possible client call errors.
//
//   - StatusCode is the HTTP status code, e.g. 200
//   - Message is the HTTP message, e.g. "OK"
//   - Body is the HTTP body returned by a request.
type Error struct {
	StatusCode int
	Message    string
	Body       []byte
}

// Error returns the error as a string.
func (err *Error) Error() string {
	var body string
	if err.Body == nil {
		body = "nil"
	} else if bl := len(err.Body); bl == 0 {
		body = "empty"
	} else {

		StatusCode: resp.StatusCode,
		Message:    resp.Status[4:],
		Body:       body,
	}
}

// NewURLBuilder creates a new URL builder for the client with the given key.
//
// key is one of the defined lower case letters to specify an endpoint.
// See [Endpoints used by the API] for details.
//
// [Endpoints used by the API]: https://zettelstore.de/manual/h/00001012920000
func (c *Client) NewURLBuilder(key byte) *api.URLBuilder {
	return api.NewURLBuilder(c.base, key)
}
func (*Client) newRequest(ctx context.Context, method string, ub *api.URLBuilder, body io.Reader) (*http.Request, error) {
	return http.NewRequestWithContext(ctx, method, ub.String(), body)
}

func (c *Client) executeRequest(req *http.Request) (*http.Response, error) {
	if c.token != "" {
		req.Header.Add("Authorization", c.tokenType+" "+c.token)
	}
	resp, err := c.client.Do(req)
	if err != nil {
		if resp != nil && resp.Body != nil {
			resp.Body.Close()
			_ = resp.Body.Close()
		}
		return nil, err
	}
	return resp, err
}

func (c *Client) buildAndExecuteRequest(
	ctx context.Context, method string, ub *api.URLBuilder, body io.Reader, h http.Header) (*http.Response, error) {
	ctx context.Context,
	method string,
	ub *api.URLBuilder,
	body io.Reader,
) (*http.Response, error) {
	req, err := c.newRequest(ctx, method, ub, body)
	if err != nil {
		return nil, err
	}
	err = c.updateToken(ctx)
	if err != nil {
		return nil, err
	}
	for key, val := range h {
		req.Header[key] = append(req.Header[key], val...)
	}
	return c.executeRequest(req)
}

// SetAuth sets authentication data.
//
// username and password are the same values that are used to authenticate via the Web-UI.
func (c *Client) SetAuth(username, password string) {
	c.username = username
	c.password = password
	c.token = ""
	c.tokenType = ""
	c.expires = time.Time{}
}

	if time.Now().After(c.expires) {
		return c.Authenticate(ctx)
	}
	return c.RefreshToken(ctx)
}

// Authenticate sets a new token by sending user name and password.
//
// [Client.SetAuth] should be called before.
func (c *Client) Authenticate(ctx context.Context) error {
	authData := url.Values{"username": {c.username}, "password": {c.password}}
	req, err := c.newRequest(ctx, http.MethodPost, c.NewURLBuilder('a'), strings.NewReader(authData.Encode()))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	return c.executeAuthRequest(req)
}

// RefreshToken updates the access token
//
// [Client.SetAuth] should be called before.
func (c *Client) RefreshToken(ctx context.Context) error {
	req, err := c.newRequest(ctx, http.MethodPut, c.NewURLBuilder('a'), nil)
	if err != nil {
		return err
	}
	return c.executeAuthRequest(req)
}

// CreateZettel creates a new zettel and returns its URL.
//
// data contains the zettel metadata and content, as it is stored in a file in a zettel box,
// or as returned by [Client.GetZettel].
// Metadata is separated from zettel content by an empty line.
func (c *Client) CreateZettel(ctx context.Context, data []byte) (api.ZettelID, error) {
	ub := c.NewURLBuilder('z')
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodPost, ub, bytes.NewBuffer(data), nil)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodPost, ub, bytes.NewBuffer(data))
	if err != nil {
		return api.InvalidZID, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusCreated {
		return api.InvalidZID, statusToError(resp)
	}
	b, err := io.ReadAll(resp.Body)
	if err != nil {
		return api.InvalidZID, err
	}
	if zid := api.ZettelID(b); zid.IsValid() {
		return zid, nil
	}
	return api.InvalidZID, err
}

// CreateZettelData creates a new zettel and returns its URL.
//
// data contains the zettel date, encoded as explicit struct.
func (c *Client) CreateZettelData(ctx context.Context, data api.ZettelData) (api.ZettelID, error) {
	var buf bytes.Buffer
	if _, err := sx.Print(&buf, sexp.EncodeZettel(data)); err != nil {
		return api.InvalidZID, err
	}
	ub := c.NewURLBuilder('z').AppendKVQuery(api.QueryKeyEncoding, api.EncodingData)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodPost, ub, &buf, nil)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodPost, ub, &buf)
	if err != nil {
		return api.InvalidZID, err
	}
	defer resp.Body.Close()
	rdr := sxreader.MakeReader(resp.Body)
	obj, err := rdr.Read()
	if resp.StatusCode != http.StatusCreated {
		return api.InvalidZID, statusToError(resp)
	}
	if err != nil {
		return api.InvalidZID, err
	}
	return makeZettelID(obj)
}

var bsLF = []byte{'\n'}

// QueryZettel returns a list of all Zettel.
func (c *Client) QueryZettel(ctx context.Context, query string) ([][]byte, error) {
	ub := c.NewURLBuilder('z').AppendQuery(query)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	switch resp.StatusCode {
	case http.StatusOK:
	case http.StatusNoContent:
		return nil, nil
	default:
		return nil, statusToError(resp)
	}
	if err != nil {
		return nil, err
	}
	lines := bytes.Split(data, bsLF)
	if len(lines[len(lines)-1]) == 0 {
		lines = lines[:len(lines)-1]
	}
	return lines, nil
}

// QueryZettelData returns a list of zettel metadata.
func (c *Client) QueryZettelData(ctx context.Context, query string) (string, string, []api.ZidMetaRights, error) {
	ub := c.NewURLBuilder('z').AppendKVQuery(api.QueryKeyEncoding, api.EncodingData).AppendQuery(query)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil, nil)
	if err != nil {
		return "", "", nil, err
	}
	defer resp.Body.Close()
	rdr := sxreader.MakeReader(resp.Body)
	obj, err := rdr.Read()
	switch resp.StatusCode {
	case http.StatusOK:
	case http.StatusNoContent:
		return "", "", nil, nil
	default:
		return "", "", nil, statusToError(resp)
	}
	if err != nil {
		return "", "", nil, err
	}
	vals, err := sexp.ParseList(obj, "yppp")
	if err != nil {
		return "", "", nil, err
	}
	qVals, err := sexp.ParseList(vals[1], "ys")
	if err != nil {
		return "", "", nil, err
	}
	hVals, err := sexp.ParseList(vals[2], "ys")
	if err != nil {
		return "", "", nil, err
	}
	metaList, err := parseMetaList(vals[3].(*sx.Pair))
	return sz.GoValue(qVals[1]), sz.GoValue(hVals[1]), metaList, err
}

func parseMetaList(metaPair *sx.Pair) ([]api.ZidMetaRights, error) {
	if metaPair == nil {
		return nil, fmt.Errorf("no zettel list")
	}
	if errSym := sexp.CheckSymbol(metaPair.Car(), "list"); errSym != nil {
		return nil, errSym
	}
	var result []api.ZidMetaRights
	for node := metaPair.Cdr(); !sx.IsNil(node); {
		elem, isPair := sx.GetPair(node)
		if !isPair {
			return nil, fmt.Errorf("meta-list not a proper list: %v", metaPair.String())
		}
		node = elem.Cdr()
		vals, err := sexp.ParseList(elem.Car(), "yppp")
		if err != nil {
			return nil, err
		}

		if errSym := sexp.CheckSymbol(vals[0], "zettel"); errSym != nil {
			return nil, errSym
		}

		idVals, err := sexp.ParseList(vals[1], "yi")
		if err != nil {
			return nil, err
		}
		if errSym := sexp.CheckSymbol(idVals[0], "id"); errSym != nil {
			return nil, errSym
		}
		zid, err := makeZettelID(idVals[1])
		if err != nil {
			return nil, err
		}

		meta, err := sexp.ParseMeta(vals[2].(*sx.Pair))
		if err != nil {
			return nil, err
		}

		rights, err := sexp.ParseRights(vals[3])
		if err != nil {
			return nil, err
		}

		result = append(result, api.ZidMetaRights{
			ID:     zid,
			Meta:   meta,
			Rights: rights,
		})
	}
	return result, nil
}
func makeZettelID(obj sx.Object) (api.ZettelID, error) {
	val, isInt64 := obj.(sx.Int64)
	if !isInt64 || val <= 0 {
		return api.InvalidZID, fmt.Errorf("invalid zettel ID: %v", val)
	}
	sVal := strconv.FormatInt(int64(val), 10)
	if len(sVal) < 14 {
		sVal = "00000000000000"[0:14-len(sVal)] + sVal
	}
	zid := api.ZettelID(sVal)
	if !zid.IsValid() {
		return api.InvalidZID, fmt.Errorf("invalid zettel ID: %v", val)
	}
	return zid, nil
}

// QueryAggregate returns a aggregate as a result of a query.
// It is most often used in a query with an action, where the action is either
// a metadata key of type Word or of type TagSet.
func (c *Client) QueryAggregate(ctx context.Context, query string) (api.Aggregate, error) {
	lines, err := c.QueryZettel(ctx, query)
	if err != nil {
		return nil, err
	}
	if len(lines) == 0 {
		return nil, nil
	}
	agg := make(api.Aggregate, len(lines))
	for _, line := range lines {
		if fields := bytes.Fields(line); len(fields) > 1 {
			key := string(fields[0])
			for _, field := range fields[1:] {
				if zid := api.ZettelID(string(field)); zid.IsValid() {
					agg[key] = append(agg[key], zid)
				}
			}
		}
	}
	return agg, nil
}

// UpdateZettel updates an existing zettel, specified by its zettel identifier.
// TagZettel returns the tag zettel of a given tag.
//
// This method only works if c.AllowRedirect(true) was called.
func (c *Client) TagZettel(ctx context.Context, tag string) (api.ZettelID, error) {
	return c.fetchTagOrRoleZettel(ctx, api.QueryKeyTag, tag)
}

// data contains the zettel metadata and content, as it is stored in a file in a zettel box,
// RoleZettel returns the tag zettel of a given tag.
//
// This method only works if c.AllowRedirect(true) was called.
func (c *Client) RoleZettel(ctx context.Context, role string) (api.ZettelID, error) {
	return c.fetchTagOrRoleZettel(ctx, api.QueryKeyRole, role)
}

// or as returned by [Client.GetZettel].
func (c *Client) fetchTagOrRoleZettel(ctx context.Context, key, val string) (api.ZettelID, error) {
	if c.client.CheckRedirect == nil {
		panic("client does not allow to track redirect")
	}
	ub := c.NewURLBuilder('z').AppendKVQuery(key, val)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil, nil)
	if err != nil {
		return api.InvalidZID, err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return api.InvalidZID, err
	}

// Metadata is separated from zettel content by an empty line.
	switch resp.StatusCode {
	case http.StatusNotFound:
		return "", nil
	case http.StatusFound:
		zid := api.ZettelID(data)
		if zid.IsValid() {
			return zid, nil
		}
		return api.InvalidZID, nil
	default:
		return api.InvalidZID, statusToError(resp)
	}
}

// GetZettel returns a zettel as a string.
func (c *Client) GetZettel(ctx context.Context, zid api.ZettelID, part string) ([]byte, error) {
	ub := c.NewURLBuilder('z').SetZid(zid)
	if part != "" && part != api.PartContent {
		ub.AppendKVQuery(api.QueryKeyPart, part)
	}
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	switch resp.StatusCode {
	case http.StatusOK:
	case http.StatusNoContent:
		return nil, nil
	default:
		return nil, statusToError(resp)
	}
	return data, err
}

// GetZettelData returns a zettel as a struct of its parts.
func (c *Client) GetZettelData(ctx context.Context, zid api.ZettelID) (api.ZettelData, error) {
	ub := c.NewURLBuilder('z').SetZid(zid)
	ub.AppendKVQuery(api.QueryKeyEncoding, api.EncodingData)
	ub.AppendKVQuery(api.QueryKeyPart, api.PartZettel)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil, nil)
	if err == nil {
		defer resp.Body.Close()
		if resp.StatusCode != http.StatusOK {
			return api.ZettelData{}, statusToError(resp)
		}
		rdr := sxreader.MakeReader(resp.Body)
		obj, err2 := rdr.Read()
		if err2 == nil {
			return sexp.ParseZettel(obj)
		}
	}
	return api.ZettelData{}, err
}

// GetParsedZettel return a parsed zettel in a defined encoding.
func (c *Client) GetParsedZettel(ctx context.Context, zid api.ZettelID, enc api.EncodingEnum) ([]byte, error) {
	return c.getZettelString(ctx, zid, enc, true)
}

// GetEvaluatedZettel return an evaluated zettel in a defined encoding.
func (c *Client) GetEvaluatedZettel(ctx context.Context, zid api.ZettelID, enc api.EncodingEnum) ([]byte, error) {
	return c.getZettelString(ctx, zid, enc, false)
}

func (c *Client) getZettelString(ctx context.Context, zid api.ZettelID, enc api.EncodingEnum, parseOnly bool) ([]byte, error) {
	ub := c.NewURLBuilder('z').SetZid(zid)
	ub.AppendKVQuery(api.QueryKeyEncoding, enc.String())
	ub.AppendKVQuery(api.QueryKeyPart, api.PartContent)
	if parseOnly {
		ub.AppendKVQuery(api.QueryKeyParseOnly, "")
	}
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	switch resp.StatusCode {
	case http.StatusOK:
	case http.StatusNoContent:
	default:
		return nil, statusToError(resp)
	}
	return io.ReadAll(resp.Body)
}

// GetParsedSz returns an parsed zettel as a Sexpr-decoded data structure.
func (c *Client) GetParsedSz(ctx context.Context, zid api.ZettelID, part string) (sx.Object, error) {
	return c.getSz(ctx, zid, part, true)
}

// GetEvaluatedSz returns an evaluated zettel as a Sexpr-decoded data structure.
func (c *Client) GetEvaluatedSz(ctx context.Context, zid api.ZettelID, part string) (sx.Object, error) {
	return c.getSz(ctx, zid, part, false)
}

func (c *Client) getSz(ctx context.Context, zid api.ZettelID, part string, parseOnly bool) (sx.Object, error) {
	ub := c.NewURLBuilder('z').SetZid(zid)
	ub.AppendKVQuery(api.QueryKeyEncoding, api.EncodingSz)
	if part != "" {
		ub.AppendKVQuery(api.QueryKeyPart, part)
	}
	if parseOnly {
		ub.AppendKVQuery(api.QueryKeyParseOnly, "")
	}
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return nil, statusToError(resp)
	}
	return sxreader.MakeReader(bufio.NewReaderSize(resp.Body, 8)).Read()
}

// GetMetaData returns the metadata of a zettel.
func (c *Client) GetMetaData(ctx context.Context, zid api.ZettelID) (api.MetaRights, error) {
	ub := c.NewURLBuilder('z').SetZid(zid)
	ub.AppendKVQuery(api.QueryKeyEncoding, api.EncodingData)
	ub.AppendKVQuery(api.QueryKeyPart, api.PartMeta)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil, nil)
	if err != nil {
		return api.MetaRights{}, err
	}
	defer resp.Body.Close()
	rdr := sxreader.MakeReader(resp.Body)
	obj, err := rdr.Read()
	if resp.StatusCode != http.StatusOK {
		return api.MetaRights{}, statusToError(resp)
	}
	if err != nil {
		return api.MetaRights{}, err
	}
	vals, err := sexp.ParseList(obj, "ypp")
	if err != nil {
		return api.MetaRights{}, err
	}
	if errSym := sexp.CheckSymbol(vals[0], "list"); errSym != nil {
		return api.MetaRights{}, err
	}

	meta, err := sexp.ParseMeta(vals[1].(*sx.Pair))
	if err != nil {
		return api.MetaRights{}, err
	}

	rights, err := sexp.ParseRights(vals[2])
	if err != nil {
		return api.MetaRights{}, err
	}

	return api.MetaRights{
		Meta:   meta,
		Rights: rights,
	}, nil
}

// UpdateZettel updates an existing zettel.
func (c *Client) UpdateZettel(ctx context.Context, zid api.ZettelID, data []byte) error {
	ub := c.NewURLBuilder('z').SetZid(zid)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodPut, ub, bytes.NewBuffer(data), nil)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodPut, ub, bytes.NewBuffer(data))
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusNoContent {
		return statusToError(resp)
	}
	return nil
}

// UpdateZettelData updates an existing zettel.
// UpdateZettelData updates an existing zettel, specified by its zettel identifier.
func (c *Client) UpdateZettelData(ctx context.Context, zid api.ZettelID, data api.ZettelData) error {
	var buf bytes.Buffer
	if _, err := sx.Print(&buf, sexp.EncodeZettel(data)); err != nil {
		return err
	}
	ub := c.NewURLBuilder('z').SetZid(zid).AppendKVQuery(api.QueryKeyEncoding, api.EncodingData)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodPut, ub, &buf, nil)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodPut, ub, &buf)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusNoContent {
		return statusToError(resp)
	}
	return nil
}

// RenameZettel renames a zettel.
//
// This function is deprecated and will be removed in v0.19 (or later).
func (c *Client) RenameZettel(ctx context.Context, oldZid, newZid api.ZettelID) error {
	ub := c.NewURLBuilder('z').SetZid(oldZid)
	h := http.Header{
		api.HeaderDestination: {c.NewURLBuilder('z').SetZid(newZid).String()},
	}
	resp, err := c.buildAndExecuteRequest(ctx, api.MethodMove, ub, nil, h)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusNoContent {
		return statusToError(resp)
	}
	return nil
}

// DeleteZettel deletes a zettel with the given identifier.
func (c *Client) DeleteZettel(ctx context.Context, zid api.ZettelID) error {
	ub := c.NewURLBuilder('z').SetZid(zid)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodDelete, ub, nil, nil)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodDelete, ub, nil)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusNoContent {
		return statusToError(resp)
	}
	return nil
}

// ExecuteCommand will execute a given command at the Zettelstore.
//
// See [API commands] for a list of valid commands.
//
// [API commands]: https://zettelstore.de/manual/h/00001012080100
func (c *Client) ExecuteCommand(ctx context.Context, command api.Command) error {
	ub := c.NewURLBuilder('x').AppendKVQuery(api.QueryKeyCommand, string(command))
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodPost, ub, nil, nil)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodPost, ub, nil)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusNoContent {
		return statusToError(resp)
	}
	return nil
}

// GetVersionInfo returns version information.
func (c *Client) GetVersionInfo(ctx context.Context) (VersionInfo, error) {
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, c.NewURLBuilder('x'), nil, nil)
	if err != nil {
		return VersionInfo{}, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return VersionInfo{}, statusToError(resp)
	}
	rdr := sxreader.MakeReader(resp.Body)
	obj, err := rdr.Read()
	if err == nil {
		if vals, errVals := sexp.ParseList(obj, "iiiss"); errVals == nil {
			return VersionInfo{
				Major: int(vals[0].(sx.Int64)),
				Minor: int(vals[1].(sx.Int64)),
				Patch: int(vals[2].(sx.Int64)),
				Info:  vals[3].(sx.String).GetValue(),
				Hash:  vals[4].(sx.String).GetValue(),
			}, nil
		}
	}
	return VersionInfo{}, err
}

// VersionInfo contains version information.
type VersionInfo struct {
	Major int
	Minor int
	Patch int
	Info  string
	Hash  string
}

// GetApplicationZid returns the zettel identifier used to configure client
// application with the given name.
func (c *Client) GetApplicationZid(ctx context.Context, appname string) (api.ZettelID, error) {
	mr, err := c.GetMetaData(ctx, api.ZidAppDirectory)
	if err != nil {
		return api.InvalidZID, err
	}
	key := appname + "-zid"
	val, found := mr.Meta[key]
	if !found {
		return api.InvalidZID, fmt.Errorf("no application registered: %v", appname)
	}
	if zid := api.ZettelID(val); zid.IsValid() {
		return zid, nil
	}
	return api.InvalidZID, fmt.Errorf("invalid identifier for application %v: %v", appname, val)
}

// Get executes a GET request to the given URL and returns the read data.
func (c *Client) Get(ctx context.Context, ub *api.URLBuilder) ([]byte, error) {
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	switch resp.StatusCode {
	case http.StatusOK:
	case http.StatusNoContent:
		return nil, nil
	default:
		return nil, statusToError(resp)
	}
	data, err := io.ReadAll(resp.Body)
	return data, err
}

//-----------------------------------------------------------------------------
// Copyright (c) 2021-present Detlef Stern
//
// This file is part of zettelstore-client.
//
// Zettelstore client 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.
//
// SPDX-License-Identifier: EUPL-1.2
// SPDX-FileCopyrightText: 2021-present Detlef Stern
//-----------------------------------------------------------------------------

package client

import (
	"bufio"
	"bytes"
	"context"
	"fmt"
	"io"
	"net/http"

	"t73f.de/r/sx"
	"t73f.de/r/sx/sxreader"
	"t73f.de/r/zsc/api"
	"t73f.de/r/zsc/sexp"
	"t73f.de/r/zsc/sz"
)

var bsLF = []byte{'\n'}

// QueryZettel returns a list of all Zettel based on the given query.
//
// query is a search expression, as described in [Query the list of all zettel].
//
// The functions returns a slice of bytes slices, where each byte slice contains the
// zettel identifier within its first 14 bytes. The next byte is a space character,
// followed by the title of the zettel.
//
// [Query the list of all zettel]: https://zettelstore.de/manual/h/00001012051400
func (c *Client) QueryZettel(ctx context.Context, query string) ([][]byte, error) {
	ub := c.NewURLBuilder('z').AppendQuery(query)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	switch resp.StatusCode {
	case http.StatusOK:
	case http.StatusNoContent:
		return nil, nil
	default:
		return nil, statusToError(resp)
	}
	if err != nil {
		return nil, err
	}
	lines := bytes.Split(data, bsLF)
	if len(lines[len(lines)-1]) == 0 {
		lines = lines[:len(lines)-1]
	}
	return lines, nil
}

// QueryZettelData returns a list of zettel metadata.
//
// query is a search expression, as described in [Query the list of all zettel].
//
// The functions returns the normalized query and its human-readable representation as
// its first two result values.
//
// [Query the list of all zettel]: https://zettelstore.de/manual/h/00001012051400
func (c *Client) QueryZettelData(ctx context.Context, query string) (string, string, []api.ZidMetaRights, error) {
	ub := c.NewURLBuilder('z').AppendKVQuery(api.QueryKeyEncoding, api.EncodingData).AppendQuery(query)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil)
	if err != nil {
		return "", "", nil, err
	}
	defer resp.Body.Close()
	rdr := sxreader.MakeReader(resp.Body)
	obj, err := rdr.Read()
	switch resp.StatusCode {
	case http.StatusOK:
	case http.StatusNoContent:
		return "", "", nil, nil
	default:
		return "", "", nil, statusToError(resp)
	}
	if err != nil {
		return "", "", nil, err
	}
	vals, err := sexp.ParseList(obj, "yppp")
	if err != nil {
		return "", "", nil, err
	}
	qVals, err := sexp.ParseList(vals[1], "ys")
	if err != nil {
		return "", "", nil, err
	}
	hVals, err := sexp.ParseList(vals[2], "ys")
	if err != nil {
		return "", "", nil, err
	}
	metaList, err := parseMetaList(vals[3].(*sx.Pair))
	return sz.GoValue(qVals[1]), sz.GoValue(hVals[1]), metaList, err
}

func parseMetaList(metaPair *sx.Pair) ([]api.ZidMetaRights, error) {
	if metaPair == nil {
		return nil, fmt.Errorf("no zettel list")
	}
	if errSym := sexp.CheckSymbol(metaPair.Car(), "list"); errSym != nil {
		return nil, errSym
	}
	var result []api.ZidMetaRights
	for node := metaPair.Cdr(); !sx.IsNil(node); {
		elem, isPair := sx.GetPair(node)
		if !isPair {
			return nil, fmt.Errorf("meta-list not a proper list: %v", metaPair.String())
		}
		node = elem.Cdr()
		vals, err := sexp.ParseList(elem.Car(), "yppp")
		if err != nil {
			return nil, err
		}

		if errSym := sexp.CheckSymbol(vals[0], "zettel"); errSym != nil {
			return nil, errSym
		}

		idVals, err := sexp.ParseList(vals[1], "yi")
		if err != nil {
			return nil, err
		}
		if errSym := sexp.CheckSymbol(idVals[0], "id"); errSym != nil {
			return nil, errSym
		}
		zid, err := makeZettelID(idVals[1])
		if err != nil {
			return nil, err
		}

		meta, err := sexp.ParseMeta(vals[2].(*sx.Pair))
		if err != nil {
			return nil, err
		}

		rights, err := sexp.ParseRights(vals[3])
		if err != nil {
			return nil, err
		}

		result = append(result, api.ZidMetaRights{
			ID:     zid,
			Meta:   meta,
			Rights: rights,
		})
	}
	return result, nil
}

// QueryAggregate returns a aggregate as a result of a query.
// It is most often used in a query with an action, where the action is either
// a metadata key of type Word or of type TagSet.
//
// query is a search expression, as described in [Query the list of all zettel].
// It must contain an aggregate action.
//
// [Query the list of all zettel]: https://zettelstore.de/manual/h/00001012051400
func (c *Client) QueryAggregate(ctx context.Context, query string) (api.Aggregate, error) {
	lines, err := c.QueryZettel(ctx, query)
	if err != nil {
		return nil, err
	}
	if len(lines) == 0 {
		return nil, nil
	}
	agg := make(api.Aggregate, len(lines))
	for _, line := range lines {
		if fields := bytes.Fields(line); len(fields) > 1 {
			key := string(fields[0])
			for _, field := range fields[1:] {
				if zid := api.ZettelID(string(field)); zid.IsValid() {
					agg[key] = append(agg[key], zid)
				}
			}
		}
	}
	return agg, nil
}

// TagZettel returns the identifier of the tag zettel for a given tag.
//
// This method only works if c.AllowRedirect(true) was called.
func (c *Client) TagZettel(ctx context.Context, tag string) (api.ZettelID, error) {
	return c.fetchTagOrRoleZettel(ctx, api.QueryKeyTag, tag)
}

// RoleZettel returns the identifier of the tag zettel for a given role.
//
// This method only works if c.AllowRedirect(true) was called.
func (c *Client) RoleZettel(ctx context.Context, role string) (api.ZettelID, error) {
	return c.fetchTagOrRoleZettel(ctx, api.QueryKeyRole, role)
}

func (c *Client) fetchTagOrRoleZettel(ctx context.Context, key, val string) (api.ZettelID, error) {
	if c.client.CheckRedirect == nil {
		panic("client does not allow to track redirect")
	}
	ub := c.NewURLBuilder('z').AppendKVQuery(key, val)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil)
	if err != nil {
		return api.InvalidZID, err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return api.InvalidZID, err
	}

	switch resp.StatusCode {
	case http.StatusNotFound:
		return "", nil
	case http.StatusFound:
		zid := api.ZettelID(data)
		if zid.IsValid() {
			return zid, nil
		}
		return api.InvalidZID, nil
	default:
		return api.InvalidZID, statusToError(resp)
	}
}

// GetZettel returns a zettel as a byte slice.
//
// part must be one of "meta", "content", or "zettel".
//
// The format of the byte slice is described in [Layout of a zettel].
//
// [Layout of a zettel]: https://zettelstore.de/manual/h/00001006000000
func (c *Client) GetZettel(ctx context.Context, zid api.ZettelID, part string) ([]byte, error) {
	ub := c.NewURLBuilder('z').SetZid(zid)
	if part != "" && part != api.PartContent {
		ub.AppendKVQuery(api.QueryKeyPart, part)
	}
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	switch resp.StatusCode {
	case http.StatusOK:
	case http.StatusNoContent:
		return nil, nil
	default:
		return nil, statusToError(resp)
	}
	return data, err
}

// GetZettelData returns a zettel as a struct of its parts.
func (c *Client) GetZettelData(ctx context.Context, zid api.ZettelID) (api.ZettelData, error) {
	ub := c.NewURLBuilder('z').SetZid(zid)
	ub.AppendKVQuery(api.QueryKeyEncoding, api.EncodingData)
	ub.AppendKVQuery(api.QueryKeyPart, api.PartZettel)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil)
	if err == nil {
		defer resp.Body.Close()
		if resp.StatusCode != http.StatusOK {
			return api.ZettelData{}, statusToError(resp)
		}
		rdr := sxreader.MakeReader(resp.Body)
		obj, err2 := rdr.Read()
		if err2 == nil {
			return sexp.ParseZettel(obj)
		}
	}
	return api.ZettelData{}, err
}

// GetParsedZettel return a parsed zettel in a specified text-based encoding.
//
// A parsed zettel is just read from its box and is not processed any further.
//
// Valid encoding values are given as constants. They are described in more
// detail in [Encodings available via the API].
//
// [Encodings available via the API]: https://zettelstore.de/manual/h/00001012920500
func (c *Client) GetParsedZettel(ctx context.Context, zid api.ZettelID, enc api.EncodingEnum) ([]byte, error) {
	return c.getZettelString(ctx, zid, enc, true)
}

// GetEvaluatedZettel return an evaluated zettel in a specified text-based encoding.
//
// An evaluated zettel was parsed, and any transclusions etc. are resolved.
// This is the zettel representation you typically see on the Web UI.
//
// Valid encoding values are given as constants. They are described in more
// detail in [Encodings available via the API].
//
// [Encodings available via the API]: https://zettelstore.de/manual/h/00001012920500
func (c *Client) GetEvaluatedZettel(ctx context.Context, zid api.ZettelID, enc api.EncodingEnum) ([]byte, error) {
	return c.getZettelString(ctx, zid, enc, false)
}

func (c *Client) getZettelString(ctx context.Context, zid api.ZettelID, enc api.EncodingEnum, parseOnly bool) ([]byte, error) {
	ub := c.NewURLBuilder('z').SetZid(zid)
	ub.AppendKVQuery(api.QueryKeyEncoding, enc.String())
	ub.AppendKVQuery(api.QueryKeyPart, api.PartContent)
	if parseOnly {
		ub.AppendKVQuery(api.QueryKeyParseOnly, "")
	}
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	switch resp.StatusCode {
	case http.StatusOK:
	case http.StatusNoContent:
	default:
		return nil, statusToError(resp)
	}
	return io.ReadAll(resp.Body)
}

// GetParsedSz returns a part of an parsed zettel as a Sexpr-decoded data structure.
//
// A parsed zettel is just read from its box and is not processed any further.
//
// part must be one of "meta", "content", or "zettel".
//
// Basically, this function returns the sz encoding of a part of a zettel.
func (c *Client) GetParsedSz(ctx context.Context, zid api.ZettelID, part string) (sx.Object, error) {
	return c.getSz(ctx, zid, part, true)
}

// GetEvaluatedSz returns an evaluated zettel as a Sexpr-decoded data structure.
//
// An evaluated zettel was parsed, and any transclusions etc. are resolved.
// This is the zettel representation you typically see on the Web UI.
//
// part must be one of "meta", "content", or "zettel".
//
// Basically, this function returns the sz encoding of a part of a zettel.
func (c *Client) GetEvaluatedSz(ctx context.Context, zid api.ZettelID, part string) (sx.Object, error) {
	return c.getSz(ctx, zid, part, false)
}

func (c *Client) getSz(ctx context.Context, zid api.ZettelID, part string, parseOnly bool) (sx.Object, error) {
	ub := c.NewURLBuilder('z').SetZid(zid)
	ub.AppendKVQuery(api.QueryKeyEncoding, api.EncodingSz)
	if part != "" {
		ub.AppendKVQuery(api.QueryKeyPart, part)
	}
	if parseOnly {
		ub.AppendKVQuery(api.QueryKeyParseOnly, "")
	}
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return nil, statusToError(resp)
	}
	return sxreader.MakeReader(bufio.NewReaderSize(resp.Body, 8)).Read()
}

// GetMetaData returns the metadata of a zettel.
func (c *Client) GetMetaData(ctx context.Context, zid api.ZettelID) (api.MetaRights, error) {
	ub := c.NewURLBuilder('z').SetZid(zid)
	ub.AppendKVQuery(api.QueryKeyEncoding, api.EncodingData)
	ub.AppendKVQuery(api.QueryKeyPart, api.PartMeta)
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil)
	if err != nil {
		return api.MetaRights{}, err
	}
	defer resp.Body.Close()
	rdr := sxreader.MakeReader(resp.Body)
	obj, err := rdr.Read()
	if resp.StatusCode != http.StatusOK {
		return api.MetaRights{}, statusToError(resp)
	}
	if err != nil {
		return api.MetaRights{}, err
	}
	vals, err := sexp.ParseList(obj, "ypp")
	if err != nil {
		return api.MetaRights{}, err
	}
	if errSym := sexp.CheckSymbol(vals[0], "list"); errSym != nil {
		return api.MetaRights{}, err
	}

	meta, err := sexp.ParseMeta(vals[1].(*sx.Pair))
	if err != nil {
		return api.MetaRights{}, err
	}

	rights, err := sexp.ParseRights(vals[2])
	if err != nil {
		return api.MetaRights{}, err
	}

	return api.MetaRights{
		Meta:   meta,
		Rights: rights,
	}, nil
}

// GetVersionInfo returns version information of the Zettelstore that is used.
func (c *Client) GetVersionInfo(ctx context.Context) (VersionInfo, error) {
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, c.NewURLBuilder('x'), nil)
	if err != nil {
		return VersionInfo{}, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return VersionInfo{}, statusToError(resp)
	}
	rdr := sxreader.MakeReader(resp.Body)
	obj, err := rdr.Read()
	if err == nil {
		if vals, errVals := sexp.ParseList(obj, "iiiss"); errVals == nil {
			return VersionInfo{
				Major: int(vals[0].(sx.Int64)),
				Minor: int(vals[1].(sx.Int64)),
				Patch: int(vals[2].(sx.Int64)),
				Info:  vals[3].(sx.String).GetValue(),
				Hash:  vals[4].(sx.String).GetValue(),
			}, nil
		}
	}
	return VersionInfo{}, err
}

// VersionInfo contains version information of the associated Zettelstore.
//
//   - Major is an integer containing the major software version of Zettelstore.
//     If its value is greater than zero, different major versions are not compatible.
//   - Minor is an integer specifying the minor software version for the given major version.
//     If the major version is greater than zero, minor versions are backward compatible.
//   - Patch is an integer that specifies a change within a minor version.
//     A version that have equal major and minor versions and differ in patch version are
//     always compatible, even if the major version equals zero.
//   - Info contains some optional text, i.e. it may be the empty string. Typically, Info
//     specifies a developer version by containing the string "dev".
//   - Hash contains the value of the source code version stored in the Zettelstore repository.
//     You can use it to reproduce bugs that occured, when source code was changed since
//     its introduction.
type VersionInfo struct {
	Major int
	Minor int
	Patch int
	Info  string
	Hash  string
}

// GetApplicationZid returns the zettel identifier used to configure a client
// application with the given name.
func (c *Client) GetApplicationZid(ctx context.Context, appname string) (api.ZettelID, error) {
	mr, err := c.GetMetaData(ctx, api.ZidAppDirectory)
	if err != nil {
		return api.InvalidZID, err
	}
	key := appname + "-zid"
	val, found := mr.Meta[key]
	if !found {
		return api.InvalidZID, fmt.Errorf("no application registered: %v", appname)
	}
	if zid := api.ZettelID(val); zid.IsValid() {
		return zid, nil
	}
	return api.InvalidZID, fmt.Errorf("invalid identifier for application %v: %v", appname, val)
}

// Get executes a GET request to the given URL and returns the read data.
func (c *Client) Get(ctx context.Context, ub *api.URLBuilder) ([]byte, error) {
	resp, err := c.buildAndExecuteRequest(ctx, http.MethodGet, ub, nil)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	switch resp.StatusCode {
	case http.StatusOK:
	case http.StatusNoContent:
		return nil, nil
	default:
		return nil, statusToError(resp)
	}
	data, err := io.ReadAll(resp.Body)
	return data, err
}

module t73f.de/r/zsc

go 1.22
go 1.23

require (
	t73f.de/r/sx v0.0.0-20240513163553-ec4fcc6539ca
	t73f.de/r/sxwebs v0.0.0-20240613142113-66fc5a284245
	t73f.de/r/webs v0.0.0-20240617100047-8730e9917915
	t73f.de/r/sx v0.0.0-20240814083626-4df0ec6454b5
	t73f.de/r/sxwebs v0.0.0-20241031144449-53c3b2ed1a6f
	t73f.de/r/webs v0.0.0-20241031141359-cd4f76a622cd
)

t73f.de/r/sx v0.0.0-20240513163553-ec4fcc6539ca h1:vvDqiuUfBLf+t/gpiSyqIFAdvZ7FLigOH38bqMY+v8k=
t73f.de/r/sx v0.0.0-20240513163553-ec4fcc6539ca/go.mod h1:G9pD1j2R6y9ZkPBb81mSnmwaAvTOg7r6jKp/OF7WeFA=
t73f.de/r/sxwebs v0.0.0-20240613142113-66fc5a284245 h1:raE7KUgoGsp2DzXOko9dDXEsSJ/VvoXCDYeICx7i6uo=
t73f.de/r/sxwebs v0.0.0-20240613142113-66fc5a284245/go.mod h1:ErPBVUyE2fOktL/8M7lp/PR93wP/o9RawMajB1uSqj8=
t73f.de/r/webs v0.0.0-20240617100047-8730e9917915 h1:rwUaPBIH3shrUIkmw51f4RyCplsCU+ISZHailsLiHTE=
t73f.de/r/webs v0.0.0-20240617100047-8730e9917915/go.mod h1:UGAAtul0TK5ACeZ6zTS3SX6GqwMFXxlUpHiV8oqNq5w=
t73f.de/r/sx v0.0.0-20240814083626-4df0ec6454b5 h1:ug4hohM6pK28M8Uo0o3+XvjBure2wfEtuCnHVIdqBZY=
t73f.de/r/sx v0.0.0-20240814083626-4df0ec6454b5/go.mod h1:VRvsWoBErPKvMieDMMk1hsh1tb9sA4ijEQWGw/TbtQ0=
t73f.de/r/sxwebs v0.0.0-20241031144449-53c3b2ed1a6f h1:VJ4S7YWy9tCJuFz5MckqUjjktPaf0kpnTkNBVRVXpo4=
t73f.de/r/sxwebs v0.0.0-20241031144449-53c3b2ed1a6f/go.mod h1:IaM+U+LvYTYeuiIS5cwZW6kcEpdwoKBYVCU7LZr4Sgk=
t73f.de/r/webs v0.0.0-20241031141359-cd4f76a622cd h1:+7cqJonXKDso+uPvsvOPl7BiLkhj8VQT/Has8qC5VIQ=
t73f.de/r/webs v0.0.0-20241031141359-cd4f76a622cd/go.mod h1:NSoOON8be62MfQZzlCApK27Jt2zhIa6Vrmo9RJ4tOnQ=

		inp.Next()
		return true
	}
	return false
}

// IsEOLEOS returns true if char is either EOS or EOL.
func IsEOLEOS(ch rune) bool {
func IsEOLEOS(ch rune) bool { return ch == EOS || ch == '\n' || ch == '\r' }
	switch ch {
	case EOS, '\n', '\r':
		return true
	}
	return false
}

// EatEOL transforms both "\r" and "\r\n" into "\n".
func (inp *Input) EatEOL() {
	switch inp.Ch {
	case '\r':
		if inp.Peek() == '\n' {
			inp.Next()

// SetPos allows to reset the read position.
func (inp *Input) SetPos(pos int) {
	if inp.Pos != pos {
		inp.readPos = pos
		inp.Next()
	}
}

// SkipSpace reads while the current character is not a space character.
func (inp *Input) SkipSpace() {
	for ch := inp.Ch; IsSpace(ch); {
		ch = inp.Next()
	}
}

// SkipToEOL reads until the next end-of-line.
func (inp *Input) SkipToEOL() {
	for {
		switch inp.Ch {
		case EOS, '\n', '\r':
			return

	case ' ', '\t':
		return true
	case '\n', '\r', EOS:
		return false
	}
	return unicode.IsSpace(ch)
}

// IsSpace returns true if current character is a whitespace.
func (inp *Input) IsSpace() bool { return IsSpace(inp.Ch) }

//-----------------------------------------------------------------------------
// Copyright (c) 2022-present Detlef Stern
//
// This file is part of zettelstore-client.
//
// Zettelstore client 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.
//
// SPDX-License-Identifier: EUPL-1.2
// SPDX-FileCopyrightText: 2022-present Detlef Stern
//-----------------------------------------------------------------------------

// Package maps provides utility functions to work with maps.
package maps

import "sort"

// Keys returns the sorted list of string keys of the given map.
func Keys[T any](m map[string]T) []string {
	if len(m) == 0 {
		return nil
	}
	result := make([]string, 0, len(m))
	for k := range m {
		result = append(result, k)

		meta2sz(zettel.Meta),
		sx.MakeList(sx.MakeSymbol("rights"), sx.Int64(int64(zettel.Rights))),
		sx.MakeList(sx.MakeSymbol("encoding"), sx.MakeString(zettel.Encoding)),
		sx.MakeList(sx.MakeSymbol("content"), sx.MakeString(zettel.Content)),
	)
}

// ParseZettel parses an object to contain all needed data for a zettel.
func ParseZettel(obj sx.Object) (api.ZettelData, error) {
	vals, err := ParseList(obj, "ypppp")
	if err != nil {
		return api.ZettelData{}, err
	}
	if errSym := CheckSymbol(vals[0], "zettel"); errSym != nil {
		return api.ZettelData{}, errSym

	}
	if i < len(spec) {
		return nil, ErrElementsMissing
	}
	return result, nil
}

// ErrElementsMissing is returned,
// if ParseList is called with a list smaller than the number of type specifications.
var ErrElementsMissing = errors.New("spec contains more data")

// ErrNoSpec is returned,
// if ParseList if called with a list greater than the number of type specifications.
var ErrNoSpec = errors.New("no spec for elements")

// CheckSymbol ensures that the given object is a symbol with the given name.
func CheckSymbol(obj sx.Object, name string) error {
	sym, isSymbol := sx.GetSymbol(obj)
	if !isSymbol {
		return fmt.Errorf("object %v/%T is not a symbol", obj, obj)
	}
	if got := sym.GetValue(); got != name {
		return fmt.Errorf("symbol %q expected, but got: %q", name, got)
	}
	return nil
}

	SymSTRONG     = sx.MakeSymbol("strong")
	symSUB        = sx.MakeSymbol("sub")
	symSUP        = sx.MakeSymbol("sup")
	symTABLE      = sx.MakeSymbol("table")
	symTBODY      = sx.MakeSymbol("tbody")
	symTHEAD      = sx.MakeSymbol("thead")
	symTD         = sx.MakeSymbol("td")
	symTH         = sx.MakeSymbol("th")
	symTR         = sx.MakeSymbol("tr")
	SymUL         = sx.MakeSymbol("ul")
)

// Symbols for HTML attribute keys
var (
	symAttrAlt    = sx.MakeSymbol("alt")

//-----------------------------------------------------------------------------
// Copyright (c) 2023-present Detlef Stern
//
// This file is part of zettelstore-client.
//
// Zettelstore client 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.
//
// SPDX-License-Identifier: EUPL-1.2
// SPDX-FileCopyrightText: 2023-present Detlef Stern
//-----------------------------------------------------------------------------

package shtml

import (
	"strings"

	"t73f.de/r/zsc/api"
)

// LangStack is a stack to store the nesting of "lang" attribute values.
// It is used to generate typographically correct quotes.
type LangStack []string

// NewLangStack creates a new language stack.
func NewLangStack(lang string) LangStack {
	ls := make([]string, 1, 16)
	ls[0] = lang
	return ls
}

// Reset restores the language stack to its initial value.
func (ls *LangStack) Reset() {
	*ls = (*ls)[0:1]
}

// Push adds a new language value.
func (ls *LangStack) Push(lang string) {
	*ls = append(*ls, lang)
}

// Pop removes the topmost language value.
func (ls *LangStack) Pop() {
	*ls = (*ls)[0 : len(*ls)-1]
}

// Top returns the topmost language value.
func (ls *LangStack) Top() string {
	return (*ls)[len(*ls)-1]
}

// Dup duplicates the topmost language value.
func (ls *LangStack) Dup() {
	*ls = append(*ls, (*ls)[len(*ls)-1])
}

// QuoteInfo contains language specific data about quotes.
type QuoteInfo struct {
	primLeft, primRight string
	secLeft, secRight   string
	nbsp                bool
}

// GetPrimary returns the primary left and right quote entity.
func (qi *QuoteInfo) GetPrimary() (string, string) {
	return qi.primLeft, qi.primRight
}

// GetSecondary returns the secondary left and right quote entity.
func (qi *QuoteInfo) GetSecondary() (string, string) {
	return qi.secLeft, qi.secRight
}

// GetQuotes returns quotes based on a nesting level.
func (qi *QuoteInfo) GetQuotes(level uint) (string, string) {
	if level%2 == 0 {
		return qi.GetPrimary()
	}
	return qi.GetSecondary()
}

// GetNBSp returns true, if there must be a non-breaking space between the
// quote entities and the quoted text.
func (qi *QuoteInfo) GetNBSp() bool { return qi.nbsp }

var langQuotes = map[string]*QuoteInfo{
	"":              {""", """, """, """, false},
	api.ValueLangEN: {"“", "”", "‘", "’", false},
	"de":            {"„", "“", "‚", "‘", false},
	"fr":            {"«", "»", "‹", "›", true},
}

// GetQuoteInfo returns language specific data about quotes.
func GetQuoteInfo(lang string) *QuoteInfo {
	langFields := strings.FieldsFunc(lang, func(r rune) bool { return r == '-' || r == '_' })
	for len(langFields) > 0 {
		langSup := strings.Join(langFields, "-")
		quotes, ok := langQuotes[langSup]
		if ok {
			return quotes
		}
		langFields = langFields[0 : len(langFields)-1]
	}
	return langQuotes[""]
}

	ev.bindMetadata()
	ev.bindBlocks()
	ev.bindInlines()
	return ev
}

// SetUnique sets a prefix to make several HTML ids unique.
func (tr *Evaluator) SetUnique(s string) { tr.unique = s }
func (ev *Evaluator) SetUnique(s string) { ev.unique = s }

// IsValidName returns true, if name is a valid symbol name.
func (tr *Evaluator) IsValidName(s string) bool { return s != "" }
func isValidName(s string) bool { return s != "" }

// EvaluateAttrbute transforms the given attributes into a HTML s-expression.
func (tr *Evaluator) EvaluateAttrbute(a attrs.Attributes) *sx.Pair {
func EvaluateAttrbute(a attrs.Attributes) *sx.Pair {
	if len(a) == 0 {
		return nil
	}
	plist := sx.Nil()
	keys := a.Keys()
	for i := len(keys) - 1; i >= 0; i-- {
		key := keys[i]
		if key != attrs.DefaultAttribute && tr.IsValidName(key) {
		if key != attrs.DefaultAttribute && isValidName(key) {
			plist = plist.Cons(sx.Cons(sx.MakeSymbol(key), sx.MakeString(a[key])))
		}
	}
	if plist == nil {
		return nil
	}
	return plist.Cons(sxhtml.SymAttr)

	if err := env.err; err != nil {
		return nil, err
	}
	return result.List(), nil
}

// Endnotes returns a SHTML object with all collected endnotes.
func (ev *Evaluator) Endnotes(env *Environment) *sx.Pair {
func Endnotes(env *Environment) *sx.Pair {
	if env.err != nil || len(env.endnotes) == 0 {
		return nil
	}

	var result sx.ListBuilder
	result.Add(SymOL)
	result.Add(sx.Nil().Cons(sx.Cons(SymAttrClass, sx.MakeString("zs-endnotes"))).Cons(sxhtml.SymAttr))

	}
	return result.List()
}

// Environment where sz objects are evaluated to shtml objects
type Environment struct {
	err          error
	langStack    []string
	langStack    LangStack
	endnotes     []endnoteInfo
	quoteNesting uint
}
type endnoteInfo struct {
	noteID  string    // link id
	noteAST sx.Vector // Endnote as list of AST inline elements
	attrs   *sx.Pair  // attrs a-list
	noteHx  *sx.Pair  // Endnote as SxHTML
}

// MakeEnvironment builds a new evaluation environment.
func MakeEnvironment(lang string) Environment {
	langStack := make([]string, 1, 16)
	langStack[0] = lang
	return Environment{
		err:          nil,
		langStack:    langStack,
		langStack:    NewLangStack(lang),
		endnotes:     nil,
		quoteNesting: 0,
	}
}

// GetError returns the last error found.
func (env *Environment) GetError() error { return env.err }

// Reset the environment.
func (env *Environment) Reset() {
	env.langStack = env.langStack[0:1]
	env.langStack.Reset()
	env.endnotes = nil
	env.quoteNesting = 0
}

// PushAttribute adds the current attributes to the environment.
// pushAttribute adds the current attributes to the environment.
func (env *Environment) pushAttributes(a attrs.Attributes) {
	if value, ok := a.Get("lang"); ok {
		env.langStack = append(env.langStack, value)
		env.langStack.Push(value)
	} else {
		env.langStack = append(env.langStack, env.getLanguage())
		env.langStack.Dup()
	}
}

// popAttributes removes the current attributes from the envrionment
func (env *Environment) popAttributes() {
// popAttributes removes the current attributes from the envrionment.
func (env *Environment) popAttributes() { env.langStack.Pop() }
	env.langStack = env.langStack[0 : len(env.langStack)-1]
}


// getLanguage returns the current language
func (env *Environment) getLanguage() string {
	return env.langStack[len(env.langStack)-1]
// getLanguage returns the current language.
func (env *Environment) getLanguage() string { return env.langStack.Top() }

func (env *Environment) getQuotes() (string, string, bool) {
	qi := GetQuoteInfo(env.getLanguage())
	leftQ, rightQ := qi.GetQuotes(env.quoteNesting)
	return leftQ, rightQ, qi.GetNBSp()
}

// EvalFn is a function to be called for evaluation.
type EvalFn func(sx.Vector, *Environment) sx.Object

func (ev *Evaluator) bind(sym *sx.Symbol, minArgs int, fn EvalFn) {
	symVal := sym.GetValue()

	ev.fns[symVal] = fn
}

func (ev *Evaluator) bindMetadata() {
	ev.bind(sz.SymMeta, 0, ev.evalList)
	evalMetaString := func(args sx.Vector, env *Environment) sx.Object {
		a := make(attrs.Attributes, 2).
			Set("name", ev.getSymbol(args[0], env).GetValue()).
			Set("name", getSymbol(args[0], env).GetValue()).
			Set("content", getString(args[1], env).GetValue())
		return ev.EvaluateMeta(a)
	}
	ev.bind(sz.SymTypeCredential, 2, evalMetaString)
	ev.bind(sz.SymTypeEmpty, 2, evalMetaString)
	ev.bind(sz.SymTypeID, 2, evalMetaString)
	ev.bind(sz.SymTypeNumber, 2, evalMetaString)

			sb.WriteString(getString(elem.Car(), env).GetValue())
		}
		s := sb.String()
		if len(s) > 0 {
			s = s[1:]
		}
		a := make(attrs.Attributes, 2).
			Set("name", ev.getSymbol(args[0], env).GetValue()).
			Set("name", getSymbol(args[0], env).GetValue()).
			Set("content", s)
		return ev.EvaluateMeta(a)
	}
	ev.bind(sz.SymTypeIDSet, 2, evalMetaSet)
	ev.bind(sz.SymTypeTagSet, 2, evalMetaSet)
	ev.bind(sz.SymTypeZettelmarkup, 2, func(args sx.Vector, env *Environment) sx.Object {
		a := make(attrs.Attributes, 2).
			Set("name", ev.getSymbol(args[0], env).GetValue()).
			Set("name", getSymbol(args[0], env).GetValue()).
			Set("content", text.EvaluateInlineString(getList(args[1], env)))
		return ev.EvaluateMeta(a)
	})
}

// EvaluateMeta returns HTML meta object for an attribute.
func (ev *Evaluator) EvaluateMeta(a attrs.Attributes) *sx.Pair {
	return sx.Nil().Cons(ev.EvaluateAttrbute(a)).Cons(SymMeta)
	return sx.Nil().Cons(EvaluateAttrbute(a)).Cons(SymMeta)
}

func (ev *Evaluator) bindBlocks() {
	ev.bind(sz.SymBlock, 0, ev.evalList)
	ev.bind(sz.SymPara, 0, func(args sx.Vector, env *Environment) sx.Object {
		return ev.evalSlice(args, env).Cons(SymP)
	})
	ev.bind(sz.SymHeading, 5, func(args sx.Vector, env *Environment) sx.Object {
		nLevel := getInt64(args[0], env)
		if nLevel <= 0 {
			env.err = fmt.Errorf("%v is a negative level", nLevel)
			env.err = fmt.Errorf("%v is a negative heading level", nLevel)
			return sx.Nil()
		}
		level := strconv.FormatInt(nLevel+ev.headingOffset, 10)
		headingSymbol := sx.MakeSymbol("h" + level)

		a := ev.GetAttributes(args[1], env)
		a := GetAttributes(args[1], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		if fragment := getString(args[3], env).GetValue(); fragment != "" {
			a = a.Set("id", ev.unique+fragment)
		}

		if result, _ := ev.EvaluateList(args[4:], env); result != nil {
			if len(a) > 0 {
				result = result.Cons(ev.EvaluateAttrbute(a))
				result = result.Cons(EvaluateAttrbute(a))
			}
			return result.Cons(headingSymbol)
		}
		return sx.MakeList(headingSymbol, sx.MakeString("<MISSING TEXT>"))
	})
	ev.bind(sz.SymThematic, 0, func(args sx.Vector, env *Environment) sx.Object {
		result := sx.Nil()
		if len(args) > 0 {
			if attrList := getList(args[0], env); attrList != nil {
				result = result.Cons(ev.EvaluateAttrbute(sz.GetAttributes(attrList)))
				result = result.Cons(EvaluateAttrbute(sz.GetAttributes(attrList)))
			}
		}
		return result.Cons(SymHR)
	})

	ev.bind(sz.SymListOrdered, 0, ev.makeListFn(SymOL))
	ev.bind(sz.SymListUnordered, 0, ev.makeListFn(SymUL))

		}
		return result.List()
	})

	ev.bind(sz.SymTable, 1, func(args sx.Vector, env *Environment) sx.Object {
		thead := sx.Nil()
		if header := getList(args[0], env); !sx.IsNil(header) {
			thead = sx.Nil().Cons(ev.evalTableRow(header, env)).Cons(symTHEAD)
			thead = sx.Nil().Cons(ev.evalTableRow(symTH, header, env)).Cons(symTHEAD)
		}

		var tbody sx.ListBuilder
		if len(args) > 1 {
			tbody.Add(symTBODY)
			for _, row := range args[1:] {
				tbody.Add(ev.evalTableRow(getList(row, env), env))
				tbody.Add(ev.evalTableRow(symTD, getList(row, env), env))
			}
		}

		table := sx.Nil()
		if !tbody.IsEmpty() {
			table = table.Cons(tbody.List())
		}

	ev.bind(sz.SymCellRight, 0, ev.makeCellFn("right"))

	ev.bind(sz.SymRegionBlock, 2, ev.makeRegionFn(SymDIV, true))
	ev.bind(sz.SymRegionQuote, 2, ev.makeRegionFn(symBLOCKQUOTE, false))
	ev.bind(sz.SymRegionVerse, 2, ev.makeRegionFn(SymDIV, false))

	ev.bind(sz.SymVerbatimComment, 1, func(args sx.Vector, env *Environment) sx.Object {
		if ev.GetAttributes(args[0], env).HasDefault() {
		if GetAttributes(args[0], env).HasDefault() {
			if len(args) > 1 {
				if s := getString(args[1], env); s.GetValue() != "" {
					return sx.Nil().Cons(s).Cons(sxhtml.SymBlockComment)
				}
			}
		}
		return nil
	})
	ev.bind(sz.SymVerbatimEval, 2, func(args sx.Vector, env *Environment) sx.Object {
		return ev.evalVerbatim(ev.GetAttributes(args[0], env).AddClass("zs-eval"), getString(args[1], env))
		return evalVerbatim(GetAttributes(args[0], env).AddClass("zs-eval"), getString(args[1], env))
	})
	ev.bind(sz.SymVerbatimHTML, 2, ev.evalHTML)
	ev.bind(sz.SymVerbatimMath, 2, func(args sx.Vector, env *Environment) sx.Object {
		return ev.evalVerbatim(ev.GetAttributes(args[0], env).AddClass("zs-math"), getString(args[1], env))
		return evalVerbatim(GetAttributes(args[0], env).AddClass("zs-math"), getString(args[1], env))
	})
	ev.bind(sz.SymVerbatimProg, 2, func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		content := getString(args[1], env)
		if a.HasDefault() {
			content = sx.MakeString(visibleReplacer.Replace(content.GetValue()))
		}
		return ev.evalVerbatim(a, content)
		return evalVerbatim(a, content)
	})
	ev.bind(sz.SymVerbatimZettel, 0, nilFn)
	ev.bind(sz.SymBLOB, 3, func(args sx.Vector, env *Environment) sx.Object {
		return ev.evalBLOB(getList(args[0], env), getString(args[1], env), getString(args[2], env))
		return evalBLOB(getList(args[0], env), getString(args[1], env), getString(args[2], env))
	})
	ev.bind(sz.SymTransclude, 2, func(args sx.Vector, env *Environment) sx.Object {
		ref, isPair := sx.GetPair(args[1])
		if !isPair {
			return sx.Nil()
		}
		refKind := ref.Car()
		if sx.IsNil(refKind) {
			return sx.Nil()
		}
		if refValue := getString(ref.Tail().Car(), env); refValue.GetValue() != "" {
			if refSym, isRefSym := sx.GetSymbol(refKind); isRefSym && refSym.IsEqual(sz.SymRefStateExternal) {
				a := ev.GetAttributes(args[0], env).Set("src", refValue.GetValue()).AddClass("external")
				return sx.Nil().Cons(sx.Nil().Cons(ev.EvaluateAttrbute(a)).Cons(SymIMG)).Cons(SymP)
			if refSym, isRefSym := sx.GetSymbol(refKind); isRefSym && refSym.IsEqualSymbol(sz.SymRefStateExternal) {
				a := GetAttributes(args[0], env).Set("src", refValue.GetValue()).AddClass("external")
				return sx.Nil().Cons(sx.Nil().Cons(EvaluateAttrbute(a)).Cons(SymIMG)).Cons(SymP)
			}
			return sx.MakeList(
				sxhtml.SymInlineComment,
				sx.MakeString("transclude"),
				refKind,
				sx.MakeString("->"),
				refValue,

	for node := term; node != nil; node = node.Tail() {
		elem := ev.Eval(node.Car(), env)
		result.Add(elem)
	}
	return result.List()
}

func (ev *Evaluator) evalTableRow(pairs *sx.Pair, env *Environment) *sx.Pair {
func (ev *Evaluator) evalTableRow(sym *sx.Symbol, pairs *sx.Pair, env *Environment) *sx.Pair {
	if pairs == nil {
		return nil
	}
	var row sx.ListBuilder
	row.Add(symTR)
	for pair := pairs; pair != nil; pair = pair.Tail() {
		row.Add(ev.Eval(pair.Car(), env))
		row.Add(sx.Cons(sym, ev.Eval(pair.Car(), env)))
	}
	return row.List()
}
func (ev *Evaluator) makeCellFn(align string) EvalFn {
	return func(args sx.Vector, env *Environment) sx.Object {
		tdata := ev.evalSlice(args, env)
		if align != "" {
			tdata = tdata.Cons(ev.EvaluateAttrbute(attrs.Attributes{"class": align}))
			tdata = tdata.Cons(EvaluateAttrbute(attrs.Attributes{"class": align}))
		}
		return tdata.Cons(symTD)
		return tdata
	}
}

func (ev *Evaluator) makeRegionFn(sym *sx.Symbol, genericToClass bool) EvalFn {
	return func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		if genericToClass {
			if val, found := a.Get(""); found {
				a = a.Remove("").AddClass(val)
			}
		}
		var result sx.ListBuilder
		result.Add(sym)
		if len(a) > 0 {
			result.Add(ev.EvaluateAttrbute(a))
			result.Add(EvaluateAttrbute(a))
		}
		if region, isPair := sx.GetPair(args[1]); isPair {
			if evalRegion := ev.EvalPairList(region, env); evalRegion != nil {
				result.ExtendBang(evalRegion)
			}
		}
		if len(args) > 2 {
			if cite, _ := ev.EvaluateList(args[2:], env); cite != nil {
				result.Add(cite.Cons(symCITE))
			}
		}
		return result.List()
	}
}

func (ev *Evaluator) evalVerbatim(a attrs.Attributes, s sx.String) sx.Object {
func evalVerbatim(a attrs.Attributes, s sx.String) sx.Object {
	a = setProgLang(a)
	code := sx.Nil().Cons(s)
	if al := ev.EvaluateAttrbute(a); al != nil {
	if al := EvaluateAttrbute(a); al != nil {
		code = code.Cons(al)
	}
	code = code.Cons(symCODE)
	return sx.Nil().Cons(code).Cons(symPRE)
}

func (ev *Evaluator) bindInlines() {
	ev.bind(sz.SymInline, 0, ev.evalList)
	ev.bind(sz.SymText, 1, func(args sx.Vector, env *Environment) sx.Object { return getString(args[0], env) })
	ev.bind(sz.SymSoft, 0, func(sx.Vector, *Environment) sx.Object { return sx.MakeString(" ") })
	ev.bind(sz.SymHard, 0, func(sx.Vector, *Environment) sx.Object { return sx.Nil().Cons(symBR) })

	ev.bind(sz.SymLinkInvalid, 2, func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		var inline *sx.Pair
		if len(args) > 2 {
			inline = ev.evalSlice(args[2:], env)
		}
		if inline == nil {
			inline = sx.Nil().Cons(ev.Eval(args[1], env))
		}
		return inline.Cons(SymSPAN)
	})
	evalHREF := func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		refValue := getString(args[1], env)
		return ev.evalLink(a.Set("href", refValue.GetValue()), refValue, args[2:], env)
	}
	ev.bind(sz.SymLinkZettel, 2, evalHREF)
	ev.bind(sz.SymLinkSelf, 2, evalHREF)
	ev.bind(sz.SymLinkFound, 2, evalHREF)
	ev.bind(sz.SymLinkBroken, 2, func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		refValue := getString(args[1], env)
		return ev.evalLink(a.AddClass("broken"), refValue, args[2:], env)
	})
	ev.bind(sz.SymLinkHosted, 2, evalHREF)
	ev.bind(sz.SymLinkBased, 2, evalHREF)
	ev.bind(sz.SymLinkQuery, 2, func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		refValue := getString(args[1], env)
		query := "?" + api.QueryKeyQuery + "=" + url.QueryEscape(refValue.GetValue())
		return ev.evalLink(a.Set("href", query), refValue, args[2:], env)
	})
	ev.bind(sz.SymLinkExternal, 2, func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		refValue := getString(args[1], env)
		return ev.evalLink(a.Set("href", refValue.GetValue()).AddClass("external"), refValue, args[2:], env)
		return ev.evalLink(a.Set("href", refValue.GetValue()).Add("rel", "external"), refValue, args[2:], env)
	})

	ev.bind(sz.SymEmbed, 3, func(args sx.Vector, env *Environment) sx.Object {
		ref := getList(args[1], env)
		syntax := getString(args[2], env).GetValue()
		if syntax == api.ValueSyntaxSVG {
			embedAttr := sx.MakeList(
				sxhtml.SymAttr,
				sx.Cons(SymAttrType, sx.MakeString("image/svg+xml")),
				sx.Cons(SymAttrSrc, sx.MakeString("/"+getString(ref.Tail(), env).GetValue()+".svg")),
			)
			return sx.MakeList(
				SymFIGURE,
				sx.MakeList(
					SymEMBED,
					embedAttr,
				),
			)
		}
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		a = a.Set("src", getString(ref.Tail().Car(), env).GetValue())
		if len(args) > 3 {
			var sb strings.Builder
			flattenText(&sb, sx.MakeList(args[3:]...))
			if d := sb.String(); d != "" {
				a = a.Set("alt", d)
			}
		}
		return sx.MakeList(SymIMG, ev.EvaluateAttrbute(a))
		return sx.MakeList(SymIMG, EvaluateAttrbute(a))
	})
	ev.bind(sz.SymEmbedBLOB, 3, func(args sx.Vector, env *Environment) sx.Object {
		a, syntax, data := ev.GetAttributes(args[0], env), getString(args[1], env), getString(args[2], env)
		a, syntax, data := GetAttributes(args[0], env), getString(args[1], env), getString(args[2], env)
		summary, hasSummary := a.Get(api.KeySummary)
		if !hasSummary {
			summary = ""
		}
		return ev.evalBLOB(
		return evalBLOB(
			sx.MakeList(sxhtml.SymListSplice, sx.MakeString(summary)),
			syntax,
			data,
		)
	})

	ev.bind(sz.SymCite, 2, func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		result := sx.Nil()
		if key := getString(args[1], env); key.GetValue() != "" {
			if len(args) > 2 {
				result = ev.evalSlice(args[2:], env).Cons(sx.MakeString(", "))
			}
			result = result.Cons(key)
		}
		if len(a) > 0 {
			result = result.Cons(ev.EvaluateAttrbute(a))
			result = result.Cons(EvaluateAttrbute(a))
		}
		if result == nil {
			return nil
		}
		return result.Cons(SymSPAN)
	})
	ev.bind(sz.SymMark, 3, func(args sx.Vector, env *Environment) sx.Object {
		result := ev.evalSlice(args[3:], env)
		if !ev.noLinks {
			if fragment := getString(args[2], env).GetValue(); fragment != "" {
				a := attrs.Attributes{"id": fragment + ev.unique}
				return result.Cons(ev.EvaluateAttrbute(a)).Cons(SymA)
				return result.Cons(EvaluateAttrbute(a)).Cons(SymA)
			}
		}
		return result.Cons(SymSPAN)
	})
	ev.bind(sz.SymEndnote, 1, func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		attrPlist := sx.Nil()
		if len(a) > 0 {
			if attrs := ev.EvaluateAttrbute(a); attrs != nil {
			if attrs := EvaluateAttrbute(a); attrs != nil {
				attrPlist = attrs.Tail()
			}
		}

		noteNum := strconv.Itoa(len(env.endnotes) + 1)
		noteID := ev.unique + noteNum
		env.endnotes = append(env.endnotes, endnoteInfo{

	ev.bind(sz.SymFormatQuote, 1, ev.evalQuote)
	ev.bind(sz.SymFormatSpan, 1, ev.makeFormatFn(SymSPAN))
	ev.bind(sz.SymFormatStrong, 1, ev.makeFormatFn(SymSTRONG))
	ev.bind(sz.SymFormatSub, 1, ev.makeFormatFn(symSUB))
	ev.bind(sz.SymFormatSuper, 1, ev.makeFormatFn(symSUP))

	ev.bind(sz.SymLiteralComment, 1, func(args sx.Vector, env *Environment) sx.Object {
		if ev.GetAttributes(args[0], env).HasDefault() {
		if GetAttributes(args[0], env).HasDefault() {
			if len(args) > 1 {
				if s := getString(ev.Eval(args[1], env), env); s.GetValue() != "" {
					return sx.Nil().Cons(s).Cons(sxhtml.SymInlineComment)
				}
			}
		}
		return sx.Nil()
	})
	ev.bind(sz.SymLiteralHTML, 2, ev.evalHTML)
	ev.bind(sz.SymLiteralInput, 2, func(args sx.Vector, env *Environment) sx.Object {
		return ev.evalLiteral(args, nil, symKBD, env)
		return evalLiteral(args, nil, symKBD, env)
	})
	ev.bind(sz.SymLiteralMath, 2, func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env).AddClass("zs-math")
		return ev.evalLiteral(args, a, symCODE, env)
		a := GetAttributes(args[0], env).AddClass("zs-math")
		return evalLiteral(args, a, symCODE, env)
	})
	ev.bind(sz.SymLiteralOutput, 2, func(args sx.Vector, env *Environment) sx.Object {
		return ev.evalLiteral(args, nil, symSAMP, env)
		return evalLiteral(args, nil, symSAMP, env)
	})
	ev.bind(sz.SymLiteralProg, 2, func(args sx.Vector, env *Environment) sx.Object {
		return ev.evalLiteral(args, nil, symCODE, env)
		return evalLiteral(args, nil, symCODE, env)
	})

	ev.bind(sz.SymLiteralZettel, 0, nilFn)
}

func (ev *Evaluator) makeFormatFn(sym *sx.Symbol) EvalFn {
	return func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		a := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		if val, hasClass := a.Get(""); hasClass {
			a = a.Remove("").AddClass(val)
		}
		res := ev.evalSlice(args[1:], env)
		if len(a) > 0 {
			res = res.Cons(ev.EvaluateAttrbute(a))
			res = res.Cons(EvaluateAttrbute(a))
		}
		return res.Cons(sym)
	}
}

type quoteData struct {
	primLeft, primRight string
	secLeft, secRight   string
	nbsp                bool
}

var langQuotes = map[string]quoteData{
	"":              {""", """, """, """, false},
	api.ValueLangEN: {"“", "”", "‘", "’", false},
	"de":            {"„", "“", "‚", "‘", false},
	"fr":            {"«", "»", "‹", "›", true},
}

func getQuoteData(lang string) quoteData {
	langFields := strings.FieldsFunc(lang, func(r rune) bool { return r == '-' || r == '_' })
	for len(langFields) > 0 {
		langSup := strings.Join(langFields, "-")
		quotes, ok := langQuotes[langSup]
		if ok {
			return quotes
		}
		langFields = langFields[0 : len(langFields)-1]
	}
	return langQuotes[""]
}

func getQuotes(data *quoteData, env *Environment) (string, string) {
	if env.quoteNesting%2 == 0 {
		return data.primLeft, data.primRight
	}
	return data.secLeft, data.secRight
}

func (ev *Evaluator) evalQuote(args sx.Vector, env *Environment) sx.Object {
	a := ev.GetAttributes(args[0], env)
	a := GetAttributes(args[0], env)
	env.pushAttributes(a)
	defer env.popAttributes()

	if val, hasClass := a.Get(""); hasClass {
		a = a.Remove("").AddClass(val)
	}
	quotes := getQuoteData(env.getLanguage())
	leftQ, rightQ := getQuotes(&quotes, env)
	leftQ, rightQ, withNbsp := env.getQuotes()

	env.quoteNesting++
	res := ev.evalSlice(args[1:], env)
	env.quoteNesting--

	lastPair := res.LastPair()
	if lastPair.IsNil() {
		res = sx.Cons(sx.MakeList(sxhtml.SymNoEscape, sx.MakeString(leftQ), sx.MakeString(rightQ)), sx.Nil())
	} else {
		if quotes.nbsp {
		if withNbsp {
			lastPair.AppendBang(sx.MakeList(sxhtml.SymNoEscape, sx.MakeString(" "), sx.MakeString(rightQ)))
			res = res.Cons(sx.MakeList(sxhtml.SymNoEscape, sx.MakeString(leftQ), sx.MakeString(" ")))
		} else {
			lastPair.AppendBang(sx.MakeList(sxhtml.SymNoEscape, sx.MakeString(rightQ)))
			res = res.Cons(sx.MakeList(sxhtml.SymNoEscape, sx.MakeString(leftQ)))
		}
	}
	if len(a) > 0 {
		res = res.Cons(ev.EvaluateAttrbute(a))
		res = res.Cons(EvaluateAttrbute(a))
		return res.Cons(SymSPAN)
	}
	return res.Cons(sxhtml.SymListSplice)
}

var visibleReplacer = strings.NewReplacer(" ", "\u2423")

func (ev *Evaluator) evalLiteral(args sx.Vector, a attrs.Attributes, sym *sx.Symbol, env *Environment) sx.Object {
func evalLiteral(args sx.Vector, a attrs.Attributes, sym *sx.Symbol, env *Environment) sx.Object {
	if a == nil {
		a = ev.GetAttributes(args[0], env)
		a = GetAttributes(args[0], env)
	}
	a = setProgLang(a)
	literal := getString(args[1], env).GetValue()
	if a.HasDefault() {
		a = a.RemoveDefault()
		literal = visibleReplacer.Replace(literal)
	}
	res := sx.Nil().Cons(sx.MakeString(literal))
	if len(a) > 0 {
		res = res.Cons(ev.EvaluateAttrbute(a))
		res = res.Cons(EvaluateAttrbute(a))
	}
	return res.Cons(sym)
}
func setProgLang(a attrs.Attributes) attrs.Attributes {
	if val, found := a.Get(""); found {
		a = a.AddClass("language-" + val).Remove("")
	}
	return a
}

func (ev *Evaluator) evalHTML(args sx.Vector, env *Environment) sx.Object {
	if s := getString(ev.Eval(args[1], env), env); s.GetValue() != "" && IsSafe(s.GetValue()) {
		return sx.Nil().Cons(s).Cons(sxhtml.SymNoEscape)
	}
	return nil
}

func (ev *Evaluator) evalBLOB(description *sx.Pair, syntax, data sx.String) sx.Object {
func evalBLOB(description *sx.Pair, syntax, data sx.String) sx.Object {
	if data.GetValue() == "" {
		return sx.Nil()
	}
	switch syntax.GetValue() {
	case "":
		return sx.Nil()
	case api.ValueSyntaxSVG:

	}
	if env.err == nil {
		return result.List()
	}
	return nil
}

// EvaluatePairList evaluates a list of lists.
// EvalPairList evaluates a list of lists.
func (ev *Evaluator) EvalPairList(pair *sx.Pair, env *Environment) *sx.Pair {
	var result sx.ListBuilder
	for node := pair; node != nil; node = node.Tail() {
		elem := ev.Eval(node.Car(), env)
		result.Add(elem)
	}
	if env.err == nil {
		return result.List()
	}
	return nil
}

func (ev *Evaluator) evalLink(a attrs.Attributes, refValue sx.String, inline sx.Vector, env *Environment) sx.Object {
	result := ev.evalSlice(inline, env)
	if len(inline) == 0 {
		result = sx.Nil().Cons(refValue)
	}
	if ev.noLinks {
		return result.Cons(SymSPAN)
	}
	return result.Cons(ev.EvaluateAttrbute(a)).Cons(SymA)
	return result.Cons(EvaluateAttrbute(a)).Cons(SymA)
}

func (ev *Evaluator) getSymbol(obj sx.Object, env *Environment) *sx.Symbol {
func getSymbol(obj sx.Object, env *Environment) *sx.Symbol {
	if env.err == nil {
		if sym, ok := sx.GetSymbol(obj); ok {
			return sym
		}
		env.err = fmt.Errorf("%v/%T is not a symbol", obj, obj)
	}
	return sx.MakeSymbol("???")

	}
	env.err = fmt.Errorf("%v/%T is not a number", val, val)
	return -1017
}

// GetAttributes evaluates the given arg in the given environment and returns
// the contained attributes.
func (ev *Evaluator) GetAttributes(arg sx.Object, env *Environment) attrs.Attributes {
func GetAttributes(arg sx.Object, env *Environment) attrs.Attributes {
	return sz.GetAttributes(getList(arg, env))
}

var unsafeSnippets = []string{
	"<script", "</script",
	"<iframe", "</iframe",
}

// SPDX-FileCopyrightText: 2022-present Detlef Stern
//-----------------------------------------------------------------------------

package sz

import "t73f.de/r/sx"

// Various constants for Zettel data. Some of them are technically variables.
// Various constants for Zettel data. They are technically variables.

var (
	// Symbols for Metanodes
	SymBlock  = sx.MakeSymbol("BLOCK")
	SymInline = sx.MakeSymbol("INLINE")
	SymMeta   = sx.MakeSymbol("META")

	// Symbols for Zettel noMakede types.

			}
		}
		return MakeMeta(m), nil
	}
	return nil, nil
}

// Meta map metadata keys to MetaValue.
type Meta map[string]MetaValue

// MetaValue is an extended metadata value:
//
//   - Type: the type assiciated with the metata key
//   - Key: the metadata key itself
//   - Value: the metadata value as an (sx-) object.
type MetaValue struct {
	Type  string
	Key   string
	Value sx.Object
}

// MakeMeta build a Meta based on a list of metadata objects.
func MakeMeta(obj sx.Object) Meta {
	if result := doMakeMeta(obj); len(result) > 0 {
		return result
	}
	return nil
}
func doMakeMeta(obj sx.Object) Meta {

	next = next.Tail()
	result.Type = typeSym.GetValue()
	result.Key = keySym.GetValue()
	result.Value = next.Car()
	return result, true
}

// GetString return the metadata string value associated with the given key.
func (m Meta) GetString(key string) string {
	if v, found := m[key]; found {
		return GoValue(v.Value)
	}
	return ""
}

// GetPair return the metadata value associated with the given key,
// as a list of objects.
func (m Meta) GetPair(key string) *sx.Pair {
	if mv, found := m[key]; found {
		if pair, isPair := sx.GetPair(mv.Value); isPair {
			return pair
		}
	}
	return nil

		SymLinkExternal: walkChildrenInlines4,
		SymLinkFound:    walkChildrenInlines4,
		SymLinkHosted:   walkChildrenInlines4,
		SymLinkInvalid:  walkChildrenInlines4,
		SymLinkQuery:    walkChildrenInlines4,
		SymLinkSelf:     walkChildrenInlines4,
		SymLinkZettel:   walkChildrenInlines4,
		SymEmbed:        walkChildrenInlines4,
		SymEmbed:        walkChildrenEmbed,
		SymCite:         walkChildrenInlines4,
		SymFormatDelete: walkChildrenInlines3,
		SymFormatEmph:   walkChildrenInlines3,
		SymFormatInsert: walkChildrenInlines3,
		SymFormatMark:   walkChildrenInlines3,
		SymFormatQuote:  walkChildrenInlines3,
		SymFormatStrong: walkChildrenInlines3,

		}
		n.SetCar(Walk(v, n.Head(), env))
	}
	return dn
}

func walkChildrenTable(v Visitor, tn *sx.Pair, env *sx.Pair) *sx.Pair {
	header := tn.Tail()
	header.SetCar(walkChildrenList(v, header.Tail(), env))
	for row := header.Tail(); row != nil; row = row.Tail() {
	for row := tn.Tail(); row != nil; row = row.Tail() {
		row.SetCar(walkChildrenList(v, row.Head(), env))
	}
	return tn
}

func walkChildrenMark(v Visitor, mn *sx.Pair, env *sx.Pair) *sx.Pair {
	// sym := mn.Car()
	next := mn.Tail()
	// mark := next.Car()
	next = next.Tail()
	// slug := next.Car()
	next = next.Tail()
	// fragment := next.Car()
	next.SetCdr(walkChildrenList(v, next.Tail(), env))
	return mn
}

func walkChildrenEmbed(v Visitor, en *sx.Pair, env *sx.Pair) *sx.Pair {
	// sym := en.Car()
	next := en.Tail()
	// attr := next.Car()
	next = next.Tail()
	// ref := next.Car()
	next = next.Tail()
	// syntax := next.Car()
	next = next.Tail()
	if next != nil {
		// text := next.Car()
		next.SetCar(Walk(v, next.Head(), env))
	}
	return en
}

func walkChildrenInlines4(v Visitor, ln *sx.Pair, env *sx.Pair) *sx.Pair {
	// sym := ln.Car()
	next := ln.Tail()
	// attrs := next.Car()
	next = next.Tail()
	// val3 := next.Car()

			lastPara = bn
		}
	}
}

// parseRegionLastLine parses the last line of a region and returns its inline text.
func (cp *zmkP) parseRegionLastLine() *sx.Pair {
	inp := cp.inp
	cp.clearStacked() // remove any lists defined in the region
	cp.skipSpace()
	inp.SkipSpace()
	var region sx.ListBuilder
	for {
		switch cp.inp.Ch {
		switch inp.Ch {
		case input.EOS, '\n', '\r':
			return region.List()
		}
		in := cp.parseInline()
		if in == nil {
			return region.List()
		}

	if delims < 3 {
		return nil, false
	}
	if inp.Ch != ' ' {
		return nil, false
	}
	inp.Next()
	cp.skipSpace()
	inp.SkipSpace()
	if delims > 7 {
		delims = 7
	}
	level := int64(delims - 2)
	var attrs *sx.Pair
	var text sx.ListBuilder
	for {

// parseNestedList parses a list.
func (cp *zmkP) parseNestedList() (res *sx.Pair, success bool) {
	kinds := cp.parseNestedListKinds()
	if len(kinds) == 0 {
		return nil, false
	}
	inp := cp.inp
	cp.skipSpace()
	if !kinds[len(kinds)-1].IsEqual(sz.SymListQuote) && input.IsEOLEOS(cp.inp.Ch) {
	inp.SkipSpace()
	if !kinds[len(kinds)-1].IsEqual(sz.SymListQuote) && input.IsEOLEOS(inp.Ch) {
		return nil, false
	}

	if len(kinds) < len(cp.lists) {
		cp.lists = cp.lists[:len(kinds)]
	}
	ln, newLnCount := cp.buildNestedList(kinds)

// parseDefTerm parses a term of a definition list.
func (cp *zmkP) parseDefTerm() (res *sx.Pair, success bool) {
	inp := cp.inp
	if inp.Next() != ' ' {
		return nil, false
	}
	inp.Next()
	cp.skipSpace()
	inp.SkipSpace()
	descrl := cp.descrl
	if descrl == nil {
		descrl = sx.Cons(sz.SymDescription, nil)
		cp.descrl = descrl
		res = descrl
	}
	lastPair, pos := lastPairPos(descrl)

// parseDefDescr parses a description of a definition list.
func (cp *zmkP) parseDefDescr() (res *sx.Pair, success bool) {
	inp := cp.inp
	if inp.Next() != ' ' {
		return nil, false
	}
	inp.Next()
	cp.skipSpace()
	inp.SkipSpace()
	descrl := cp.descrl
	lastPair, pos := lastPairPos(descrl)
	if descrl == nil || pos <= 0 {
		// No term given
		return nil, false
	}

func hasQueryPrefix(src []byte) bool {
	return len(src) > len(api.QueryPrefix) && string(src[:len(api.QueryPrefix)]) == api.QueryPrefix
}

func (cp *zmkP) parseReference(openCh, closeCh rune) (ref string, text *sx.Pair, _ bool) {
	inp := cp.inp
	inp.Next()
	cp.skipSpace()
	inp.SkipSpace()
	if inp.Ch == openCh {
		// Additional opening chars result in a fail
		return "", nil, false
	}
	var is sx.Vector
	pos := inp.Pos
	if !hasQueryPrefix(inp.Src[pos:]) {

			if hasSpace {
				return "", nil, false
			}
			inp.SetPos(pos)
		}
	}

	cp.skipSpace()
	inp.SkipSpace()
	pos = inp.Pos
	if !cp.readReferenceToClose(closeCh) {
		return "", nil, false
	}
	ref = strings.TrimSpace(string(inp.Src[pos:inp.Pos]))
	if inp.Next() != closeCh {
		return "", nil, false

		Cons(sz.SymMark)
	return mn, true
	// Problematisch ist, dass hier noch nicht mn.Fragment und mn.Slug gesetzt werden.
	// Evtl. muss es ein PreMark-Symbol geben
}

func (cp *zmkP) parseLinkLikeRest() (*sx.Pair, bool) {
	cp.skipSpace()
	var ins sx.Vector
	inp := cp.inp
	inp.SkipSpace()
	for inp.Ch != ']' {
		in := cp.parseInline()
		if in == nil {
			return nil, false
		}
		ins = append(ins, in)
		if input.IsEOLEOS(inp.Ch) && sz.IsBreakSym(in.Car()) {

	if inp.Next() != '%' {
		return nil, false
	}
	for inp.Ch == '%' {
		inp.Next()
	}
	attrs := cp.parseInlineAttributes()
	cp.skipSpace()
	inp.SkipSpace()
	pos := inp.Pos
	for {
		if input.IsEOLEOS(inp.Ch) {
			return sx.MakeList(
				sz.SymLiteralComment,
				attrs,
				sx.MakeString(string(inp.Src[pos:inp.Pos])),

			s := cp.parseString()
			sb.WriteString(s.GetValue())
		}
	}
}

func createLiteralNode(sym *sx.Symbol, attrs *sx.Pair, content string) *sx.Pair {
	if sym.IsEqual(sz.SymLiteralZettel) {
	if sym.IsEqualSymbol(sz.SymLiteralZettel) {
		if p := attrs.Assoc(sx.MakeString("")); p != nil {
			if val, isString := sx.GetString(p.Cdr()); isString && val.GetValue() == api.ValueSyntaxHTML {
				sym = sz.SymLiteralHTML
				attrs = attrs.RemoveAssoc(sx.MakeString(""))
			}
		}
	}

		}

		elem = cellTail.Head()
		if elem.Car().IsEqual(sz.SymText) {
			if s, isString := sx.GetString(elem.Tail().Car()); isString && s.GetValue() != "" {
				str := s.GetValue()
				cellAlign := getCellAlignment(str[len(str)-1])
				if !cellAlign.IsEqual(sz.SymCell) {
				if !cellAlign.IsEqualSymbol(sz.SymCell) {
					elem.SetCdr(sx.Cons(sx.MakeString(str[0:len(str)-1]), nil))
				}
				align[cellCount-1] = cellAlign
				cell.SetCar(cellAlign)
			}
		}
	}

		// elem is first cell inline element
		elem := cellTail.Head()
		if elem.Car().IsEqual(sz.SymText) {
			if s, isString := sx.GetString(elem.Tail().Car()); isString && s.GetValue() != "" {
				str := s.GetValue()
				cellAlign := getCellAlignment(str[0])
				if !cellAlign.IsEqual(sz.SymCell) {
				if !cellAlign.IsEqualSymbol(sz.SymCell) {
					elem.SetCdr(sx.Cons(sx.MakeString(str[1:]), nil))
					cell.SetCar(cellAlign)
				}
			}
		}
	}

// -----------------------------------------------------------------------------
// Copyright (c) 2020-present Detlef Stern
//
// This file is part of zettelstore-client.
//
// Zettelstore client 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.
//
// SPDX-License-Identifier: EUPL-1.2
// SPDX-FileCopyrightText: 2020-present Detlef Stern
// -----------------------------------------------------------------------------

package zmk

import (
	"net/url"
	"strings"

	"t73f.de/r/sx"
	"t73f.de/r/zsc/api"
	"t73f.de/r/zsc/sz"
)

// ParseReference parses a string and returns a reference.
func ParseReference(s string) *sx.Pair {
	if invalidReference(s) {
		return makePairRef(sz.SymRefStateInvalid, s)
	}
	if strings.HasPrefix(s, api.QueryPrefix) {
		return makePairRef(sz.SymRefStateQuery, s[len(api.QueryPrefix):])
	}
	if state, ok := localState(s); ok {
		if state.IsEqual(sz.SymRefStateBased) {
		if state.IsEqualSymbol(sz.SymRefStateBased) {
			s = s[1:]
		}
		_, err := url.Parse(s)
		if err == nil {
			return makePairRef(state, s)
		}
	}

	"unicode"

	"t73f.de/r/sx"
	"t73f.de/r/zsc/input"
	"t73f.de/r/zsc/sz"
)

// ParseBlocks tries to parse the input as a block element.
func ParseBlocks(inp *input.Input) *sx.Pair {
	parser := zmkP{inp: inp}

	var lastPara *sx.Pair
	var blkBuild sx.ListBuilder
	for inp.Ch != input.EOS {
		bn, cont := parser.parseBlock(lastPara)

	var pp postProcessor
	if bs := pp.visitPairList(bnl, nil); bs != nil {
		return bs.Cons(sz.SymBlock)
	}
	return nil
}

// ParseInlines tries to parse the input as an inline element.
func ParseInlines(inp *input.Input) *sx.Pair {
	parser := zmkP{inp: inp}
	var ins sx.Vector
	for inp.Ch != input.EOS {
		in := parser.parseInline()
		if in == nil {
			break

func (attrs attrMap) asPairAssoc() *sx.Pair {
	names := make([]string, 0, len(attrs))
	for n := range attrs {
		names = append(names, n)
	}
	slices.Sort(names)
	var assoc *sx.Pair = nil
	var assoc *sx.Pair
	for i := len(names) - 1; i >= 0; i-- {
		n := names[i]
		assoc = assoc.Cons(sx.Cons(sx.MakeString(n), sx.MakeString(attrs[n])))
	}
	return assoc
}

		inp.Next()
	}
	if pos < inp.Pos {
		return attrMap{"": string(inp.Src[pos:inp.Pos])}.asPairAssoc()
	}

	// No immediate name: skip spaces
	cp.skipSpace()
	inp.SkipSpace()
	return cp.parseInlineAttributes()
}

func (cp *zmkP) parseInlineAttributes() *sx.Pair {
	inp := cp.inp
	pos := inp.Pos
	if attrs, success := cp.doParseAttributes(); success {

			inp.EatEOL()
		default:
			return
		}
	}
}

func (cp *zmkP) skipSpace() {
	for inp := cp.inp; inp.Ch == ' '; {
		inp.Next()
	}
}

func isNameRune(ch rune) bool {
	return unicode.IsLetter(ch) || unicode.IsDigit(ch) || ch == '-' || ch == '_'
}

func checkTcs(t *testing.T, isBlock bool, tcs TestCases) {
	t.Helper()

	for tcn, tc := range tcs {
		t.Run(fmt.Sprintf("TC=%02d,src=%q", tcn, tc.source), func(st *testing.T) {
			st.Helper()
			ast := parseInput(tc.source, isBlock)
			sz.Walk(astWalker{}, ast, nil)
			got := ast.String()
			if tc.want != got {
				st.Errorf("\nwant=%q\n got=%q", tc.want, got)
			}
		})
	}
}
func parseInput(src string, asBlock bool) sx.Sequence {
func parseInput(src string, asBlock bool) *sx.Pair {
	inp := input.NewInput([]byte(src))
	if asBlock {
		bl := zmk.ParseBlocks(inp)
		return bl
	}
	il := zmk.ParseInlines(inp)
	return il
}

type astWalker struct{}

func (astWalker) Visit(node *sx.Pair, env *sx.Pair) sx.Object { return sx.MakeBoolean(true) }

func TestEOL(t *testing.T) {
	t.Parallel()
	for _, isBlock := range []bool{true, false} {
		checkTcs(t, isBlock, TestCases{
			{"", "()"},
			{"\n", "()"},
			{"\r", "()"},

)

// Encoder is the structure to hold relevant data to execute the encoding.
type Encoder struct {
	sb strings.Builder
}

// NewEncoder returns a new text encoder.
func NewEncoder() *Encoder {
	enc := &Encoder{
		sb: strings.Builder{},
	}
	return enc
}

// Encode the object list as a string.
func (enc *Encoder) Encode(lst *sx.Pair) string {
	enc.executeList(lst)
	result := enc.sb.String()
	enc.sb.Reset()
	return result
}

<title>Change Log</title>

<a name="0_20"></a>
<h2>Changes for Version 0.20.0 (pending)</h2>

<a name="0_19"></a>
<h2>Changes for Version 0.19.0 (pending)</h2>
<h2>Changes for Version 0.19.0 (2024-12-13)</h2>
  *  Remove support for rename operation; removed all associated constants
  *  Make quote handling in shtml public, to be used by other encoders
  *  shtml generates external links with rel attribute
  *  Add some input handling methods
  *  Enhance docs for api/client

<a name="0_18"></a>
<h2>Changes for Version 0.18.0 (2024-07-11)</h2>
  *  Add client method <code>GetApplicationZid</code> to retrieve the zettel
     identifier of an configuration zettel for a specific application.
  *  Rename to be package <code>t73f.de/r/zsc</code>
  *  Reserve some zettel identifier for future use

<title>Home</title>

This repository contains Go client software to
access [https://zettelstore.de|Zettelstore] via its API.

<h3>Latest Release: 0.18.0 (2024-07-11)</h3>
  *  [./changes.wiki#0_18|Change summary]
  *  [/timeline?p=v0.18.0&bt=v0.17.0&y=ci|Check-ins for version 0.18.0],
     [/vdiff?to=v0.18.0&from=v0.17.0|content diff]
  *  [/timeline?df=v0.18.0&y=ci|Check-ins derived from the 0.18.0 release],
     [/vdiff?from=v0.18.0&to=trunk|content diff]
<h3>Latest Release: 0.19.0 (2024-12-13)</h3>
  *  [./changes.wiki#0_19|Change summary]
  *  [/timeline?p=v0.19.0&bt=v0.18.0&y=ci|Check-ins for version 0.19],
     [/vdiff?to=v0.19.0&from=v0.18.0|content diff]
  *  [/timeline?df=v0.19.0&y=ci|Check-ins derived from the 0.19 release],
     [/vdiff?from=v0.19.0&to=trunk|content diff]
  *  [/timeline?t=release|Timeline of all past releases]

<h3>Use instructions</h3>

If you want to import this library into your own [https://go.dev/|Go] software,
you must execute a <code>go get</code> command. Since Go treats non-standard
software and non-standard platforms quite badly, you must use some non-standard
commands.

First, you must install the version control system
[https://fossil-scm.org|Fossil], which is a superior solution compared to Git,
in too many use cases. It is just a single executable, nothing more. Make sure,
it is in your search path for commands.
First, you must install the [https://fossil-scm.org|Fossil] version control
system. In too many use cases it is a superior solution compared to Git, It is
just a single executable, nothing more. Make sure, it is in your search path
for commands.

How you can execute the following Go command to retrieve a given version of
this library:

<code>GOVCS=zettelstore.de:fossil go get -x t73f.de/r/zsc@HASH</code>

where <code>HASH</code> is the hash value of the commit you want to use.