Zettelstore Client

//-----------------------------------------------------------------------------
// 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 api contains common definitions used for client and server.
package api

// ZettelID contains the identifier of a zettel. It is a string with 14 digits.
type ZettelID string

// InvalidZID is an invalif zettel identifier
const InvalidZID = ""

// IsValid returns true, if the idenfifier contains 14 digits.
func (zid ZettelID) IsValid() bool {
	if len(zid) != 14 {
		return false
	}
	for i := range 14 {
		ch := zid[i]
		if ch < '0' || '9' < ch {
			return false
		}
	}
	return true
}

//-----------------------------------------------------------------------------
// 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 api

import "fmt"

// Predefined Zettel Identifier

	MetaIDSet        = "IdentifierSet"
	MetaNumber       = "Number"
	MetaString       = "String"
	MetaTagSet       = "TagSet"
	MetaTimestamp    = "Timestamp"
	MetaURL          = "URL"
	MetaWord         = "Word"

	MetaZettelmarkup = "Zettelmarkup"
)

// Predefined general Metadata keys
const (
	KeyID           = "id"
	KeyTitle        = "title"

// 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"

	ActionSeparator = "|"

	AtomAction     = "ATOM"
	KeysAction     = "KEYS"
	MinAction      = "MIN"
	MaxAction      = "MAX"
	NumberedAction = "NUMBERED"
	RedirectAction = "REDIRECT"
	ReIndexAction  = "REINDEX"
	RSSAction      = "RSS"
	TitleAction    = "TITLE"

	ExistOperator    = "?"
	ExistNotOperator = "!?"

	SearchOperatorNot        = "!"
	SearchOperatorEqual      = "="
	SearchOperatorNotEqual   = "!="
	SearchOperatorHas        = ":"
	SearchOperatorHasNot     = "!:"
	SearchOperatorPrefix     = "["
	SearchOperatorNoPrefix   = "!["
	SearchOperatorSuffix     = "]"
	SearchOperatorNoSuffix   = "!]"
	SearchOperatorMatch      = "~"
	SearchOperatorNoMatch    = "!~"
	SearchOperatorLess       = "<"
	SearchOperatorNotLess    = "!<"
	SearchOperatorGreater    = ">"
	SearchOperatorNotGreater = "!>"
)

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

//-----------------------------------------------------------------------------
// 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 api

import (
	"net/url"
	"strings"

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

import (
	"strings"

//-----------------------------------------------------------------------------
// 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 attrs_test

import (
	"testing"

//-----------------------------------------------------------------------------
// 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 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"

	"zettelstore.de/client.fossil/api"
	"zettelstore.de/client.fossil/sexp"
	"zettelstore.de/client.fossil/sz"
	"zettelstore.de/sx.fossil"
	"zettelstore.de/sx.fossil/sxreader"
)

// Client contains all data to execute requests.
type Client struct {
	base      string

	return &Error{
		StatusCode: resp.StatusCode,
		Message:    resp.Status[4:],
		Body:       body,
	}
}

// NewURLBuilder creates a new URL builder for the client with the given key.
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 err != nil {
		return err
	}
	vals, err := sexp.ParseList(obj, "ssi")
	if err != nil {
		return err
	}
	token := string(vals[1].(sx.String))
	if len(token) < 4 {
		return fmt.Errorf("no valid token found: %q", token)
	}
	c.token = token
	c.tokenType = string(vals[0].(sx.String))
	c.expires = time.Now().Add(time.Duration(vals[2].(sx.Int64)*9/10) * time.Second)
	return nil
}

func (c *Client) updateToken(ctx context.Context) error {
	if c.username == "" {
		return nil
	}
	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.
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
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.
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)
	if err != nil {
		return api.InvalidZID, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusCreated {
		return api.InvalidZID, statusToError(resp)

// CreateZettelData creates a new zettel and returns its URL.
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)
	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 {

		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()

		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 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

	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, nil)
	if err != nil {
		return api.InvalidZID, err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	if err != 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
	}

		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)

// 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()

		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)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusNoContent {
		return statusToError(resp)
	}
	return nil
}

// UpdateZettelData updates an existing zettel.
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)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusNoContent {
		return statusToError(resp)
	}
	return nil
}

// RenameZettel renames a zettel.
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)
	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.
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)
	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:  string(vals[3].(sx.String)),
				Hash:  string(vals[4].(sx.String)),
			}, nil
		}
	}
	return VersionInfo{}, err
}

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

// 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) 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 client_test

import (
	"context"
	"flag"
	"net/http"
	"net/url"
	"testing"

	"zettelstore.de/client.fossil/api"
	"zettelstore.de/client.fossil/client"


)

func TestZettelList(t *testing.T) {
	c := getClient()
	_, err := c.QueryZettel(context.Background(), "")
	if err != nil {
		t.Error(err)

		}
		return
	}
}

func TestGetSzZettel(t *testing.T) {
	c := getClient()



	value, err := c.GetEvaluatedSz(context.Background(), api.ZidDefaultHome, api.PartContent)
	if err != nil {
		t.Error(err)
		return
	}
	if value.IsNil() {
		t.Error("No data")
	}

module zettelstore.de/client.fossil

go 1.22

require zettelstore.de/sx.fossil v0.0.0-20240304124557-67e0a1799d1d

zettelstore.de/sx.fossil v0.0.0-20240304124557-67e0a1799d1d h1:Gl5ZmdNV5wJsNMIQYjAd/sWLq2ng4NP+eglWU7lQP+I=
zettelstore.de/sx.fossil v0.0.0-20240304124557-67e0a1799d1d/go.mod h1:/iGHxFXoo6GSV04PUkwaLuFrrCa5LMorxD73iLMAruI=

//-----------------------------------------------------------------------------
// 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 input

import (
	"html"
	"unicode"
)

// ScanEntity scans either a named or a numbered entity and returns it as a string.
//
// For numbered entities (like { or ģ) html.UnescapeString returns
// sometimes other values as expected, if the number is not well-formed. This
// may happen because of some strange HTML parsing rules. But these do not
// apply to Zettelmarkup. Therefore, I parse the number here in the code.
func (inp *Input) ScanEntity() (res string, success bool) {
	if inp.Ch != '&' {
		return "", false
	}
	pos := inp.Pos
	inp.Next()
	if inp.Ch == '#' {
		inp.Next()
		if inp.Ch == 'x' || inp.Ch == 'X' {
			return inp.scanEntityBase16()
		}
		return inp.scanEntityBase10()
	}
	return inp.scanEntityNamed(pos)
}

func (inp *Input) scanEntityBase16() (string, bool) {
	inp.Next()
	if inp.Ch == ';' {
		return "", false
	}
	code := 0
	for {
		switch ch := inp.Ch; ch {
		case ';':
			inp.Next()
			if r := rune(code); isValidEntity(r) {
				return string(r), true
			}
			return "", false
		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
			code = 16*code + int(ch-'0')
		case 'a', 'b', 'c', 'd', 'e', 'f':
			code = 16*code + int(ch-'a'+10)
		case 'A', 'B', 'C', 'D', 'E', 'F':
			code = 16*code + int(ch-'A'+10)
		default:
			return "", false
		}
		if code > unicode.MaxRune {
			return "", false
		}
		inp.Next()
	}
}

func (inp *Input) scanEntityBase10() (string, bool) {
	// Base 10 code
	if inp.Ch == ';' {
		return "", false
	}
	code := 0
	for {
		switch ch := inp.Ch; ch {
		case ';':
			inp.Next()
			if r := rune(code); isValidEntity(r) {
				return string(r), true
			}
			return "", false
		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
			code = 10*code + int(ch-'0')
		default:
			return "", false
		}
		if code > unicode.MaxRune {
			return "", false
		}
		inp.Next()
	}
}
func (inp *Input) scanEntityNamed(pos int) (string, bool) {
	for {
		switch inp.Ch {
		case EOS, '\n', '\r', '&':
			return "", false
		case ';':
			inp.Next()
			es := string(inp.Src[pos:inp.Pos])
			ues := html.UnescapeString(es)
			if es == ues {
				return "", false
			}
			return ues, true
		default:
			inp.Next()
		}
	}
}

// isValidEntity checks if the given code is valid for an entity.
//
// According to https://html.spec.whatwg.org/multipage/syntax.html#character-references
// ""The numeric character reference forms described above are allowed to reference any code point
// excluding U+000D CR, noncharacters, and controls other than ASCII whitespace.""
func isValidEntity(r rune) bool {
	// No C0 control and no "code point in the range U+007F DELETE to U+009F APPLICATION PROGRAM COMMAND, inclusive."
	if r < ' ' || ('\u007f' <= r && r <= '\u009f') {
		return false
	}

	// If below any noncharacter code point, return true
	//
	// See: https://infra.spec.whatwg.org/#noncharacter
	if r < '\ufdd0' {
		return true
	}

	// First range of noncharacter code points: "(...) in the range U+FDD0 to U+FDEF, inclusive"
	if r <= '\ufdef' {
		return false
	}

	// Other noncharacter code points:
	switch r {
	case '\uFFFE', '\uFFFF',
		'\U0001FFFE', '\U0001FFFF',
		'\U0002FFFE', '\U0002FFFF',
		'\U0003FFFE', '\U0003FFFF',
		'\U0004FFFE', '\U0004FFFF',
		'\U0005FFFE', '\U0005FFFF',
		'\U0006FFFE', '\U0006FFFF',
		'\U0007FFFE', '\U0007FFFF',
		'\U0008FFFE', '\U0008FFFF',
		'\U0009FFFE', '\U0009FFFF',
		'\U000AFFFE', '\U000AFFFF',
		'\U000BFFFE', '\U000BFFFF',
		'\U000CFFFE', '\U000CFFFF',
		'\U000DFFFE', '\U000DFFFF',
		'\U000EFFFE', '\U000EFFFF',
		'\U000FFFFE', '\U000FFFFF',
		'\U0010FFFE', '\U0010FFFF':
		return false
	}
	return true
}

//-----------------------------------------------------------------------------
// 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 input_test

import (
	"testing"

	"zettelstore.de/client.fossil/input"
)

func TestScanEntity(t *testing.T) {
	t.Parallel()
	var testcases = []struct {
		text string
		exp  string
	}{
		{"", ""},
		{"a", ""},
		{"&", "&"},
		{"!", "!"},
		{"3", "3"},
		{""", "\""},
	}
	for id, tc := range testcases {
		inp := input.NewInput([]byte(tc.text))
		got, ok := inp.ScanEntity()
		if !ok {
			if tc.exp != "" {
				t.Errorf("ID=%d, text=%q: expected error, but got %q", id, tc.text, got)
			}
			if inp.Pos != 0 {
				t.Errorf("ID=%d, text=%q: input position advances to %d", id, tc.text, inp.Pos)
			}
			continue
		}
		if tc.exp != got {
			t.Errorf("ID=%d, text=%q: expected %q, but got %q", id, tc.text, tc.exp, got)
		}
	}
}

func TestScanIllegalEntity(t *testing.T) {
	t.Parallel()
	testcases := []string{"", "a", "& Input →", "	", ""}
	for i, tc := range testcases {
		inp := input.NewInput([]byte(tc))
		got, ok := inp.ScanEntity()
		if ok {
			t.Errorf("%d: scanning %q was unexpected successful, got %q", i, tc, got)
			continue
		}
	}
}

//-----------------------------------------------------------------------------
// 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 input provides an abstraction for data to be read.
package input

import "unicode/utf8"

// Input is an abstract input source
type Input struct {
	// Read-only, will never change
	Src []byte // The source string

	// Read-only, will change
	Ch      rune // current character
	Pos     int  // character position in src
	readPos int  // reading position (position after current character)
}

// NewInput creates a new input source.
func NewInput(src []byte) *Input {
	inp := &Input{Src: src}
	inp.Next()
	return inp
}

// EOS = End of source
const EOS = rune(-1)

// Next reads the next rune into inp.Ch and returns it too.
func (inp *Input) Next() rune {
	if inp.readPos >= len(inp.Src) {
		inp.Pos = len(inp.Src)
		inp.Ch = EOS
		return EOS
	}
	inp.Pos = inp.readPos
	r, w := rune(inp.Src[inp.readPos]), 1
	if r >= utf8.RuneSelf {
		r, w = utf8.DecodeRune(inp.Src[inp.readPos:])
	}
	inp.readPos += w
	inp.Ch = r
	return r
}

// Peek returns the rune following the most recently read rune without
// advancing. If end-of-source was already found peek returns EOS.
func (inp *Input) Peek() rune {
	return inp.PeekN(0)
}

// PeekN returns the n-th rune after the most recently read rune without
// advancing. If end-of-source was already found peek returns EOS.
func (inp *Input) PeekN(n int) rune {
	pos := inp.readPos + n
	if pos < len(inp.Src) {
		r := rune(inp.Src[pos])
		if r >= utf8.RuneSelf {
			r, _ = utf8.DecodeRune(inp.Src[pos:])
		}
		if r == '\t' {
			return ' '
		}
		return r
	}
	return EOS
}

// Accept checks if the given string is a prefix of the text to be parsed.
// If successful, advance position and current character.
// String must only contain bytes < 128.
// If not successful, everything remains as it is.
func (inp *Input) Accept(s string) bool {
	pos := inp.Pos
	remaining := len(inp.Src) - pos
	if s == "" || len(s) > remaining {
		return false
	}
	// According to internal documentation of bytes.Equal, the string() will not allocate any memory.
	if readPos := pos + len(s); s == string(inp.Src[pos:readPos]) {
		inp.readPos = readPos
		inp.Next()
		return true
	}
	return false
}

// IsEOLEOS returns true if char is either EOS or EOL.
func IsEOLEOS(ch rune) bool {
	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()
		}
		inp.Ch = '\n'
		inp.Next()
	case '\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()
	}
}

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

// ScanLineContent reads the reaining input stream and interprets it as lines of text.
func (inp *Input) ScanLineContent() []byte {
	result := make([]byte, 0, len(inp.Src)-inp.Pos+1)
	for {
		inp.EatEOL()
		posL := inp.Pos
		if inp.Ch == EOS {
			return result
		}
		inp.SkipToEOL()
		if len(result) > 0 {
			result = append(result, '\n')
		}
		result = append(result, inp.Src[posL:inp.Pos]...)
	}
}

//-----------------------------------------------------------------------------
// 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 input_test provides some unit-tests for reading data.
package input_test

import (
	"testing"

	"zettelstore.de/client.fossil/input"
)

func TestEatEOL(t *testing.T) {
	t.Parallel()
	inp := input.NewInput(nil)
	inp.EatEOL()
	if inp.Ch != input.EOS {
		t.Errorf("No EOS found: %q", inp.Ch)
	}
	if inp.Pos != 0 {
		t.Errorf("Pos != 0: %d", inp.Pos)
	}

	inp = input.NewInput([]byte("ABC"))
	if inp.Ch != 'A' {
		t.Errorf("First ch != 'A', got %q", inp.Ch)
	}
	inp.EatEOL()
	if inp.Ch != 'A' {
		t.Errorf("First ch != 'A', got %q", inp.Ch)
	}
}

func TestAccept(t *testing.T) {
	t.Parallel()
	testcases := []struct {
		accept string
		src    string
		acc    bool
		exp    rune
	}{
		{"", "", false, input.EOS},
		{"AB", "abc", false, 'a'},
		{"AB", "ABC", true, 'C'},
		{"AB", "AB", true, input.EOS},
		{"AB", "A", false, 'A'},
	}
	for i, tc := range testcases {
		inp := input.NewInput([]byte(tc.src))
		acc := inp.Accept(tc.accept)
		if acc != tc.acc {
			t.Errorf("%d: %q.Accept(%q) == %v, but got %v", i, tc.src, tc.accept, tc.acc, acc)
		}
		if got := inp.Ch; tc.exp != got {
			t.Errorf("%d: %q.Accept(%q) should result in run %v, but got %v", i, tc.src, tc.accept, tc.exp, got)
		}
	}
}

//-----------------------------------------------------------------------------
// 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 input

import "unicode"

// IsSpace returns true if rune is a whitespace.
func IsSpace(ch rune) bool {
	switch ch {
	case ' ', '\t':
		return true
	case '\n', '\r', EOS:
		return false
	}
	return unicode.IsSpace(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

import "sort"

func Keys[T any](m map[string]T) []string {

//-----------------------------------------------------------------------------
// 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_test

import (
	"testing"

//-----------------------------------------------------------------------------
// 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 sexp contains helper function to work with s-expression in an alien
// environment.
package sexp

import (
	"errors"
	"fmt"
	"sort"

	"zettelstore.de/client.fossil/api"
	"zettelstore.de/sx.fossil"
)

// EncodeZettel transforms zettel data into a sx object.
func EncodeZettel(zettel api.ZettelData) sx.Object {

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

func ParseZettel(obj sx.Object) (api.ZettelData, error) {
	vals, err := ParseList(obj, "ypppp")
	if err != nil {
		return api.ZettelData{}, err

	if errSym := CheckSymbol(contentVals[0], "content"); errSym != nil {
		return api.ZettelData{}, errSym
	}

	return api.ZettelData{
		Meta:     meta,
		Rights:   rights,
		Encoding: string(encVals[1].(sx.String)),
		Content:  string(contentVals[1].(sx.String)),
	}, nil
}

// EncodeMetaRights translates metadata/rights into a sx object.
func EncodeMetaRights(mr api.MetaRights) *sx.Pair {

	return sx.MakeList(
		sx.SymbolList,
		meta2sz(mr.Meta),
		sx.MakeList(sx.MakeSymbol("rights"), sx.Int64(int64(mr.Rights))),
	)
}

func meta2sz(m api.ZettelMeta) sx.Object {
	var result sx.ListBuilder
	result.Add(sx.MakeSymbol("meta"))
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	for _, k := range keys {
		val := sx.MakeList(sx.MakeSymbol(k), sx.String(m[k]))
		result.Add(val)
	}
	return result.List()
}

// ParseMeta translates the given list to metadata.
func ParseMeta(pair *sx.Pair) (api.ZettelMeta, error) {
	if err := CheckSymbol(pair.Car(), "meta"); err != nil {
		return nil, err
	}
	res := api.ZettelMeta{}
	for node := pair.Tail(); node != nil; node = node.Tail() {
		mVals, err := ParseList(node.Car(), "ys")
		if err != nil {
			return nil, err
		}
		res[(mVals[0].(*sx.Symbol)).GetValue()] = string(mVals[1].(sx.String))
	}
	return res, nil
}

// ParseRights returns the rights values of the given object.
func ParseRights(obj sx.Object) (api.ZettelRights, error) {
	rVals, err := ParseList(obj, "yi")

	if i64 < 0 && i64 >= int64(api.ZettelMaxRight) {
		return api.ZettelMaxRight, fmt.Errorf("invalid zettel right value: %v", i64)
	}
	return api.ZettelRights(i64), nil
}

// ParseList parses the given object as a proper list, based on a type specification.
func ParseList(obj sx.Object, spec string) (sx.Vector, error) {
	pair, isPair := sx.GetPair(obj)
	if !isPair {
		return nil, fmt.Errorf("not a list: %T/%v", obj, obj)
	}
	if pair == nil {
		if spec == "" {
			return nil, nil
		}
		return nil, ErrElementsMissing
	}

	result := make(sx.Vector, 0, len(spec))
	node, i := pair, 0
	for ; node != nil; i++ {
		if i >= len(spec) {
			return nil, ErrNoSpec
		}
		var val sx.Object
		var ok bool

// 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
}

//-----------------------------------------------------------------------------
// 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 sexp_test

import (
	"testing"

//-----------------------------------------------------------------------------
// Copyright (c) 2024-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: 2024-present Detlef Stern
//-----------------------------------------------------------------------------

package shtml

import "zettelstore.de/sx.fossil"

// Symbols for HTML header tags
var (
	SymBody   = sx.MakeSymbol("body")
	SymHead   = sx.MakeSymbol("head")
	SymHtml   = sx.MakeSymbol("html")
	SymMeta   = sx.MakeSymbol("meta")
	SymScript = sx.MakeSymbol("script")
	SymTitle  = sx.MakeSymbol("title")
)

// Symbols for HTML body tags
var (
	SymA          = sx.MakeSymbol("a")
	SymASIDE      = sx.MakeSymbol("aside")
	symBLOCKQUOTE = sx.MakeSymbol("blockquote")
	symBR         = sx.MakeSymbol("br")
	symCITE       = sx.MakeSymbol("cite")
	symCODE       = sx.MakeSymbol("code")
	symDD         = sx.MakeSymbol("dd")
	symDEL        = sx.MakeSymbol("del")
	SymDIV        = sx.MakeSymbol("div")
	symDL         = sx.MakeSymbol("dl")
	symDT         = sx.MakeSymbol("dt")
	symEM         = sx.MakeSymbol("em")
	SymEMBED      = sx.MakeSymbol("embed")
	SymFIGURE     = sx.MakeSymbol("figure")
	SymH1         = sx.MakeSymbol("h1")
	SymH2         = sx.MakeSymbol("h2")
	SymHR         = sx.MakeSymbol("hr")
	SymIMG        = sx.MakeSymbol("img")
	symINS        = sx.MakeSymbol("ins")
	symKBD        = sx.MakeSymbol("kbd")
	SymLI         = sx.MakeSymbol("li")
	symMARK       = sx.MakeSymbol("mark")
	SymOL         = sx.MakeSymbol("ol")
	SymP          = sx.MakeSymbol("p")
	symPRE        = sx.MakeSymbol("pre")
	symSAMP       = sx.MakeSymbol("samp")
	SymSPAN       = sx.MakeSymbol("span")
	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")
	symTR         = sx.MakeSymbol("tr")
	SymUL         = sx.MakeSymbol("ul")
)

// Symbols for HTML attribute keys
var (
	symAttrAlt    = sx.MakeSymbol("alt")
	SymAttrClass  = sx.MakeSymbol("class")
	SymAttrHref   = sx.MakeSymbol("href")
	SymAttrId     = sx.MakeSymbol("id")
	SymAttrLang   = sx.MakeSymbol("lang")
	SymAttrOpen   = sx.MakeSymbol("open")
	SymAttrRel    = sx.MakeSymbol("rel")
	SymAttrRole   = sx.MakeSymbol("role")
	SymAttrSrc    = sx.MakeSymbol("src")
	SymAttrTarget = sx.MakeSymbol("target")
	SymAttrTitle  = sx.MakeSymbol("title")
	SymAttrType   = sx.MakeSymbol("type")
	SymAttrValue  = sx.MakeSymbol("value")
)

//-----------------------------------------------------------------------------
// 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 transforms a s-expr encoded zettel AST into a s-expr representation of HTML.
package shtml

import (
	"fmt"

	"zettelstore.de/sx.fossil"
	"zettelstore.de/sx.fossil/sxhtml"
)

// Evaluator will transform a s-expression that encodes the zettel AST into an s-expression
// that represents HTML.
type Evaluator struct {

	headingOffset int64
	unique        string
	noLinks       bool // true iff output must not include links












	fns     map[string]EvalFn
	minArgs map[string]int
}

// NewEvaluator creates a new Evaluator object.
func NewEvaluator(headingOffset int) *Evaluator {



	ev := &Evaluator{

		headingOffset: int64(headingOffset),











		fns:     make(map[string]EvalFn, 128),
		minArgs: make(map[string]int, 128),
	}

	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 }




// IsValidName returns true, if name is a valid symbol name.
func (tr *Evaluator) 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 {
	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) {
			plist = plist.Cons(sx.Cons(sx.MakeSymbol(key), sx.String(a[key])))
		}
	}
	if plist == nil {
		return nil
	}
	return plist.Cons(sxhtml.SymAttr)
}

// Evaluate a metadata s-expression into a list of HTML s-expressions.
func (ev *Evaluator) Evaluate(lst *sx.Pair, env *Environment) (*sx.Pair, error) {
	result := ev.Eval(lst, env)
	if err := env.err; err != nil {
		return nil, err
	}
	pair, isPair := sx.GetPair(result)
	if !isPair {
		return nil, fmt.Errorf("evaluation does not result in a pair, but %T/%v", result, result)
	}

	for i := 0; i < len(env.endnotes); i++ {
		// May extend tr.endnotes -> do not use for i := range len(...)!!!

		if env.endnotes[i].noteHx != nil {
			continue
		}

		noteHx, _ := ev.EvaluateList(env.endnotes[i].noteAST, env)







		env.endnotes[i].noteHx = noteHx
	}

	return pair, nil
}

// EvaluateList will evaluate all list elements separately and returns them as a sx.Pair list
func (ev *Evaluator) EvaluateList(lst sx.Vector, env *Environment) (*sx.Pair, error) {
	var result sx.ListBuilder
	for _, elem := range lst {
		p := ev.Eval(elem, env)
		result.Add(p)
	}
	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 {
	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.String("zs-endnotes"))).Cons(sxhtml.SymAttr))
	for i, fni := range env.endnotes {
		noteNum := strconv.Itoa(i + 1)
		attrs := fni.attrs.Cons(sx.Cons(SymAttrClass, sx.String("zs-endnote"))).
			Cons(sx.Cons(SymAttrValue, sx.String(noteNum))).
			Cons(sx.Cons(SymAttrId, sx.String("fn:"+fni.noteID))).
			Cons(sx.Cons(SymAttrRole, sx.String("doc-endnote"))).
			Cons(sxhtml.SymAttr)

		backref := sx.Nil().Cons(sx.String("\u21a9\ufe0e")).
			Cons(sx.Nil().
				Cons(sx.Cons(SymAttrClass, sx.String("zs-endnote-backref"))).
				Cons(sx.Cons(SymAttrHref, sx.String("#fnref:"+fni.noteID))).
				Cons(sx.Cons(SymAttrRole, sx.String("doc-backlink"))).
				Cons(sxhtml.SymAttr)).
			Cons(SymA)

		var li sx.ListBuilder
		li.Add(SymLI)
		li.Add(attrs)
		li.ExtendBang(fni.noteHx)
		li.Add(sx.String(" "))
		li.Add(backref)
		result.Add(li.List())
	}
	return result.List()
}

// Environment where sz objects are evaluated to shtml objects
type Environment struct {
	err          error
	langStack    []string
	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)

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

// 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
	if minArgs > 0 {
		ev.minArgs[symVal] = minArgs
	}
}

// ResolveBinding returns the function bound to the given name.
func (ev *Evaluator) ResolveBinding(sym *sx.Symbol) EvalFn {
	if fn, found := ev.fns[sym.GetValue()]; found {
		return fn
	}
	return nil
}

// Rebind overwrites a binding, but leaves the minimum number of arguments intact.
func (ev *Evaluator) Rebind(sym *sx.Symbol, fn EvalFn) {
	symVal := sym.GetValue()
	if _, found := ev.fns[symVal]; !found {
		panic(sym)
	}
	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("content", string(getString(args[1], env)))
		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)
	ev.bind(sz.SymTypeString, 2, evalMetaString)
	ev.bind(sz.SymTypeTimestamp, 2, evalMetaString)
	ev.bind(sz.SymTypeURL, 2, evalMetaString)
	ev.bind(sz.SymTypeWord, 2, evalMetaString)

	evalMetaSet := func(args sx.Vector, env *Environment) sx.Object {
		var sb strings.Builder

		for elem := getList(args[1], env); elem != nil; elem = elem.Tail() {
			sb.WriteByte(' ')
			sb.WriteString(string(getString(elem.Car(), env)))
		}
		s := sb.String()
		if len(s) > 0 {
			s = s[1:]
		}
		a := make(attrs.Attributes, 2).
			Set("name", ev.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("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)
}

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)
			return sx.Nil()
		}
		level := strconv.FormatInt(nLevel+ev.headingOffset, 10)
		headingSymbol := sx.MakeSymbol("h" + level)

		a := ev.GetAttributes(args[1], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		if fragment := string(getString(args[3], env)); 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))
			}
			return result.Cons(headingSymbol)
		}
		return sx.MakeList(headingSymbol, sx.String("<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)))
			}
		}
		return result.Cons(SymHR)
	})

	ev.bind(sz.SymListOrdered, 0, ev.makeListFn(SymOL))
	ev.bind(sz.SymListUnordered, 0, ev.makeListFn(SymUL))
	ev.bind(sz.SymDescription, 0, func(args sx.Vector, env *Environment) sx.Object {
		if len(args) == 0 {
			return sx.Nil()
		}
		var items sx.ListBuilder
		items.Add(symDL)
		for pos := 0; pos < len(args); pos++ {
			term := ev.evalDescriptionTerm(getList(args[pos], env), env)
			items.Add(term.Cons(symDT))
			pos++
			if pos >= len(args) {
				break
			}
			ddBlock := getList(ev.Eval(args[pos], env), env)
			if ddBlock == nil {
				continue
			}
			for ddlst := ddBlock; ddlst != nil; ddlst = ddlst.Tail() {
				dditem := getList(ddlst.Car(), env)
				items.Add(dditem.Cons(symDD))
			}
		}
		return items.List()
	})
	ev.bind(sz.SymListQuote, 0, func(args sx.Vector, env *Environment) sx.Object {
		if args == nil {
			return sx.Nil()
		}
		var result sx.ListBuilder
		result.Add(symBLOCKQUOTE)
		for _, elem := range args {
			if quote, isPair := sx.GetPair(ev.Eval(elem, env)); isPair {
				result.Add(quote.Cons(sxhtml.SymListSplice))
			}
		}
		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)
		}

		var tbody sx.ListBuilder
		if len(args) > 1 {

			tbody.Add(symTBODY)
			for _, row := range args[1:] {
				tbody.Add(ev.evalTableRow(getList(row, env), env))
			}
		}

		table := sx.Nil()
		if !tbody.IsEmpty() {
			table = table.Cons(tbody.List())
		}
		if thead != nil {
			table = table.Cons(thead)
		}
		if table == nil {
			return sx.Nil()
		}
		return table.Cons(symTABLE)
	})
	ev.bind(sz.SymCell, 0, ev.makeCellFn(""))
	ev.bind(sz.SymCellCenter, 0, ev.makeCellFn("center"))
	ev.bind(sz.SymCellLeft, 0, ev.makeCellFn("left"))
	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 len(args) > 1 {
				if s := getString(args[1], env); s != "" {

					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))
	})
	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))
	})
	ev.bind(sz.SymVerbatimProg, 2, func(args sx.Vector, env *Environment) sx.Object {
		a := ev.GetAttributes(args[0], env)
		content := getString(args[1], env)
		if a.HasDefault() {
			content = sx.String(visibleReplacer.Replace(string(content)))
		}
		return ev.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))
	})
	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 != "" {
			if refSym, isRefSym := sx.GetSymbol(refKind); isRefSym && refSym.IsEqual(sz.SymRefStateExternal) {
				a := ev.GetAttributes(args[0], env).Set("src", string(refValue)).AddClass("external")
				return sx.Nil().Cons(sx.Nil().Cons(ev.EvaluateAttrbute(a)).Cons(SymIMG)).Cons(SymP)
			}
			return sx.MakeList(
				sxhtml.SymInlineComment,
				sx.String("transclude"),
				refKind,
				sx.String("->"),
				refValue,
			)
		}
		return ev.evalSlice(args, env)
	})
}

func (ev *Evaluator) makeListFn(sym *sx.Symbol) EvalFn {

	return func(args sx.Vector, env *Environment) sx.Object {
		var result sx.ListBuilder
		result.Add(sym)
		for _, elem := range args {
			item := sx.Nil().Cons(SymLI)
			if res, isPair := sx.GetPair(ev.Eval(elem, env)); isPair {
				item.ExtendBang(res)
			}
			result.Add(item)
		}
		return result.List()
	}
}

func (ev *Evaluator) evalDescriptionTerm(term *sx.Pair, env *Environment) *sx.Pair {
	var result sx.ListBuilder
	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 {

	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))
	}
	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}))
		}
		return tdata.Cons(symTD)
	}
}

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)
		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))
		}


		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 {
	a = setProgLang(a)
	code := sx.Nil().Cons(s)
	if al := ev.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.SymSpace, 0, func(args sx.Vector, env *Environment) sx.Object {
		if len(args) == 0 {
			return sx.String(" ")
		}
		return getString(args[0], env)
	})
	ev.bind(sz.SymSoft, 0, func(sx.Vector, *Environment) sx.Object { return sx.String(" ") })

	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)
		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)
		env.pushAttributes(a)
		defer env.popAttributes()
		refValue := getString(args[1], env)
		return ev.evalLink(a.Set("href", string(refValue)), 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)
		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)
		env.pushAttributes(a)
		defer env.popAttributes()
		refValue := getString(args[1], env)
		query := "?" + api.QueryKeyQuery + "=" + url.QueryEscape(string(refValue))
		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)
		env.pushAttributes(a)
		defer env.popAttributes()
		refValue := getString(args[1], env)
		return ev.evalLink(a.Set("href", string(refValue)).AddClass("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)
		if syntax == api.ValueSyntaxSVG {
			embedAttr := sx.MakeList(
				sxhtml.SymAttr,
				sx.Cons(SymAttrType, sx.String("image/svg+xml")),
				sx.Cons(SymAttrSrc, sx.String("/"+string(getString(ref.Tail(), env))+".svg")),
			)
			return sx.MakeList(

				SymFIGURE,
				sx.MakeList(
					SymEMBED,
					embedAttr,
				),
			)
		}
		a := ev.GetAttributes(args[0], env)
		a = a.Set("src", string(getString(ref.Tail().Car(), env)))
		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))
	})
	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)
		summary, hasSummary := a.Get(api.KeySummary)
		if !hasSummary {
			summary = ""
		}
		return ev.evalBLOB(
			sx.MakeList(sxhtml.SymListSplice, sx.String(summary)),
			syntax,
			data,
		)
	})

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





		noteNum := strconv.Itoa(len(env.endnotes) + 1)
		noteID := ev.unique + noteNum
		env.endnotes = append(env.endnotes, endnoteInfo{
			noteID: noteID, noteAST: args[1:], noteHx: nil, attrs: attrPlist})
		hrefAttr := sx.Nil().Cons(sx.Cons(SymAttrRole, sx.String("doc-noteref"))).
			Cons(sx.Cons(SymAttrHref, sx.String("#fn:"+noteID))).
			Cons(sx.Cons(SymAttrClass, sx.String("zs-noteref"))).
			Cons(sxhtml.SymAttr)
		href := sx.Nil().Cons(sx.String(noteNum)).Cons(hrefAttr).Cons(SymA)
		supAttr := sx.Nil().Cons(sx.Cons(SymAttrId, sx.String("fnref:"+noteID))).Cons(sxhtml.SymAttr)
		return sx.Nil().Cons(href).Cons(supAttr).Cons(symSUP)
	})

	ev.bind(sz.SymFormatDelete, 1, ev.makeFormatFn(symDEL))
	ev.bind(sz.SymFormatEmph, 1, ev.makeFormatFn(symEM))
	ev.bind(sz.SymFormatInsert, 1, ev.makeFormatFn(symINS))
	ev.bind(sz.SymFormatMark, 1, ev.makeFormatFn(symMARK))
	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 len(args) > 1 {
				if s := getString(ev.Eval(args[1], env), env); s != "" {
					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)
	})

	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)
	})

	ev.bind(sz.SymLiteralOutput, 2, func(args sx.Vector, env *Environment) sx.Object {
		return ev.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)
	})

	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)
		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 {

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)
	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)

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

	lastPair := res.LastPair()
	if lastPair.IsNil() {
		res = sx.Cons(sx.MakeList(sxhtml.SymNoEscape, sx.String(leftQ), sx.String(rightQ)), sx.Nil())
	} else {
		if quotes.nbsp {
			lastPair.AppendBang(sx.MakeList(sxhtml.SymNoEscape, sx.String(" "), sx.String(rightQ)))
			res = res.Cons(sx.MakeList(sxhtml.SymNoEscape, sx.String(leftQ), sx.String(" ")))
		} else {
			lastPair.AppendBang(sx.MakeList(sxhtml.SymNoEscape, sx.String(rightQ)))
			res = res.Cons(sx.MakeList(sxhtml.SymNoEscape, sx.String(leftQ)))
		}
	}
	if len(a) > 0 {
		res = res.Cons(ev.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 {
	if a == nil {
		a = ev.GetAttributes(args[0], env)
	}
	a = setProgLang(a)
	literal := string(getString(args[1], env))
	if a.HasDefault() {
		a = a.RemoveDefault()
		literal = visibleReplacer.Replace(literal)
	}
	res := sx.Nil().Cons(sx.String(literal))
	if len(a) > 0 {
		res = res.Cons(ev.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 != "" && IsSafe(string(s)) {
		return sx.Nil().Cons(s).Cons(sxhtml.SymNoEscape)
	}
	return nil
}

func (ev *Evaluator) evalBLOB(description *sx.Pair, syntax, data sx.String) sx.Object {
	if data == "" {
		return sx.Nil()
	}
	switch syntax {
	case "":
		return sx.Nil()
	case api.ValueSyntaxSVG:
		return sx.Nil().Cons(sx.Nil().Cons(data).Cons(sxhtml.SymNoEscape)).Cons(SymP)
	default:
		imgAttr := sx.Nil().Cons(sx.Cons(SymAttrSrc, sx.String("data:image/"+string(syntax)+";base64,"+string(data))))
		var sb strings.Builder
		flattenText(&sb, description)
		if d := sb.String(); d != "" {
			imgAttr = imgAttr.Cons(sx.Cons(symAttrAlt, sx.String(d)))
		}
		return sx.Nil().Cons(sx.Nil().Cons(imgAttr.Cons(sxhtml.SymAttr)).Cons(SymIMG)).Cons(SymP)
	}
}

func flattenText(sb *strings.Builder, lst *sx.Pair) {
	for elem := lst; elem != nil; elem = elem.Tail() {
		switch obj := elem.Car().(type) {
		case sx.String:
			sb.WriteString(string(obj))
		case *sx.Symbol:
			if obj.IsEqual(sz.SymSpace) {
				sb.WriteByte(' ')
				break
			}
		case *sx.Pair:
			flattenText(sb, obj)
		}
	}
}

func (ev *Evaluator) evalList(args sx.Vector, env *Environment) sx.Object {
	return ev.evalSlice(args, env)
}
func nilFn(sx.Vector, *Environment) sx.Object { return sx.Nil() }

// Eval evaluates an object in an environment.
func (ev *Evaluator) Eval(obj sx.Object, env *Environment) sx.Object {
	if env.err != nil {
		return sx.Nil()
	}
	if sx.IsNil(obj) {
		return obj
	}
	lst, isLst := sx.GetPair(obj)
	if !isLst {
		return obj
	}
	sym, found := sx.GetSymbol(lst.Car())
	if !found {
		env.err = fmt.Errorf("symbol expected, but got %T/%v", lst.Car(), lst.Car())
		return sx.Nil()
	}
	symVal := sym.GetValue()
	fn, found := ev.fns[symVal]
	if !found {
		env.err = fmt.Errorf("symbol %q not bound", sym)
		return sx.Nil()
	}
	var args sx.Vector
	for cdr := lst.Cdr(); !sx.IsNil(cdr); {
		pair, isPair := sx.GetPair(cdr)
		if !isPair {
			break
		}
		args = append(args, pair.Car())
		cdr = pair.Cdr()
	}
	if minArgs, hasMinArgs := ev.minArgs[symVal]; hasMinArgs {
		if minArgs > len(args) {
			env.err = fmt.Errorf("%v needs at least %d arguments, but got only %d", sym, minArgs, len(args))
			return sx.Nil()
		}
	}
	result := fn(args, env)
	if env.err != nil {
		return sx.Nil()
	}
	return result
}

func (ev *Evaluator) evalSlice(args sx.Vector, env *Environment) *sx.Pair {

	var result sx.ListBuilder
	for _, arg := range args {
		elem := ev.Eval(arg, env)
		result.Add(elem)
	}
	if env.err == nil {
		return result.List()
	}
	return nil
}

// EvaluatePairList 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)
}

func (ev *Evaluator) 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("???")
}
func getString(val sx.Object, env *Environment) sx.String {
	if env.err != nil {
		return ""
	}
	if s, ok := sx.GetString(val); ok {
		return s

	}
	if num, ok := sx.GetNumber(val); ok {
		return int64(num.(sx.Int64))
	}
	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 {
	return sz.GetAttributes(getList(arg, env))
}

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

//-----------------------------------------------------------------------------
// 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 sz

import "zettelstore.de/sx.fossil"

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

const (
	// Symbols for Metanodes
	NameBlock  = "BLOCK"
	NameInline = "INLINE"
	NameMeta   = "META"

	// Symbols for Zettel noMakede types.
	NameBLOB            = "BLOB"
	NameCell            = "CELL"
	NameCellCenter      = "CELL-CENTER"
	NameCellLeft        = "CELL-LEFT"
	NameCellRight       = "CELL-RIGHT"
	NameCite            = "CITE"
	NameDescription     = "DESCRIPTION"
	NameEmbed           = "EMBED"
	NameEmbedBLOB       = "EMBED-BLOB"
	NameEndnote         = "ENDNOTE"
	NameFormatEmph      = "FORMAT-EMPH"
	NameFormatDelete    = "FORMAT-DELETE"
	NameFormatInsert    = "FORMAT-INSERT"
	NameFormatMark      = "FORMAT-MARK"
	NameFormatQuote     = "FORMAT-QUOTE"
	NameFormatSpan      = "FORMAT-SPAN"
	NameFormatSub       = "FORMAT-SUB"
	NameFormatSuper     = "FORMAT-SUPER"
	NameFormatStrong    = "FORMAT-STRONG"
	NameHard            = "HARD"
	NameHeading         = "HEADING"
	NameLinkInvalid     = "LINK-INVALID"
	NameLinkZettel      = "LINK-ZETTEL"
	NameLinkSelf        = "LINK-SELF"
	NameLinkFound       = "LINK-FOUND"
	NameLinkBroken      = "LINK-BROKEN"
	NameLinkHosted      = "LINK-HOSTED"
	NameLinkBased       = "LINK-BASED"
	NameLinkQuery       = "LINK-QUERY"
	NameLinkExternal    = "LINK-EXTERNAL"
	NameListOrdered     = "ORDERED"
	NameListUnordered   = "UNORDERED"
	NameListQuote       = "QUOTATION"
	NameLiteralProg     = "LITERAL-CODE"
	NameLiteralComment  = "LITERAL-COMMENT"
	NameLiteralHTML     = "LITERAL-HTML"
	NameLiteralInput    = "LITERAL-INPUT"
	NameLiteralMath     = "LITERAL-MATH"
	NameLiteralOutput   = "LITERAL-OUTPUT"
	NameLiteralZettel   = "LITERAL-ZETTEL"
	NameMark            = "MARK"
	NamePara            = "PARA"
	NameRegionBlock     = "REGION-BLOCK"
	NameRegionQuote     = "REGION-QUOTE"
	NameRegionVerse     = "REGION-VERSE"
	NameSoft            = "SOFT"
	NameSpace           = "SPACE"
	NameTable           = "TABLE"
	NameText            = "TEXT"
	NameThematic        = "THEMATIC"
	NameTransclude      = "TRANSCLUDE"
	NameUnknown         = "UNKNOWN-NODE"
	NameVerbatimComment = "VERBATIM-COMMENT"
	NameVerbatimEval    = "VERBATIM-EVAL"
	NameVerbatimHTML    = "VERBATIM-HTML"
	NameVerbatimMath    = "VERBATIM-MATH"
	NameVerbatimProg    = "VERBATIM-CODE"
	NameVerbatimZettel  = "VERBATIM-ZETTEL"

	// Constant symbols for reference states.
	NameRefStateInvalid  = "INVALID"
	NameRefStateZettel   = "ZETTEL"
	NameRefStateSelf     = "SELF"
	NameRefStateFound    = "FOUND"
	NameRefStateBroken   = "BROKEN"
	NameRefStateHosted   = "HOSTED"
	NameRefStateBased    = "BASED"
	NameRefStateQuery    = "QUERY"
	NameRefStateExternal = "EXTERNAL"

	// Symbols for metadata types.
	NameTypeCredential   = "CREDENTIAL"
	NameTypeEmpty        = "EMPTY-STRING"



























	NameTypeID           = "ZID"

	NameTypeIDSet        = "ZID-SET"
	NameTypeNumber       = "NUMBER"
	NameTypeString       = "STRING"






	NameTypeTagSet       = "TAG-SET"
	NameTypeTimestamp    = "TIMESTAMP"

	NameTypeURL          = "URL"
	NameTypeWord         = "WORD"

	NameTypeZettelmarkup = "ZETTELMARKUP"

















)

var (
	// Symbols for Metanodes
	SymBlock  = sx.MakeSymbol(NameBlock)
	SymInline = sx.MakeSymbol(NameInline)
	SymMeta   = sx.MakeSymbol(NameMeta)

	// Symbols for Zettel noMakede types.
	SymBLOB            = sx.MakeSymbol(NameBLOB)
	SymCell            = sx.MakeSymbol(NameCell)
	SymCellCenter      = sx.MakeSymbol(NameCellCenter)
	SymCellLeft        = sx.MakeSymbol(NameCellLeft)
	SymCellRight       = sx.MakeSymbol(NameCellRight)
	SymCite            = sx.MakeSymbol(NameCite)
	SymDescription     = sx.MakeSymbol(NameDescription)




	SymEmbed           = sx.MakeSymbol(NameEmbed)
	SymEmbedBLOB       = sx.MakeSymbol(NameEmbedBLOB)
	SymEndnote         = sx.MakeSymbol(NameEndnote)
	SymFormatEmph      = sx.MakeSymbol(NameFormatEmph)
	SymFormatDelete    = sx.MakeSymbol(NameFormatDelete)
	SymFormatInsert    = sx.MakeSymbol(NameFormatInsert)


	SymFormatMark      = sx.MakeSymbol(NameFormatMark)
	SymFormatQuote     = sx.MakeSymbol(NameFormatQuote)
	SymFormatSpan      = sx.MakeSymbol(NameFormatSpan)
	SymFormatSub       = sx.MakeSymbol(NameFormatSub)

	SymFormatSuper     = sx.MakeSymbol(NameFormatSuper)

	SymFormatStrong    = sx.MakeSymbol(NameFormatStrong)


	SymHard            = sx.MakeSymbol(NameHard)
	SymHeading         = sx.MakeSymbol(NameHeading)
	SymLinkInvalid     = sx.MakeSymbol(NameLinkInvalid)
	SymLinkZettel      = sx.MakeSymbol(NameLinkZettel)


	SymLinkSelf        = sx.MakeSymbol(NameLinkSelf)
	SymLinkFound       = sx.MakeSymbol(NameLinkFound)
	SymLinkBroken      = sx.MakeSymbol(NameLinkBroken)
	SymLinkHosted      = sx.MakeSymbol(NameLinkHosted)

	SymLinkBased       = sx.MakeSymbol(NameLinkBased)

	SymLinkQuery       = sx.MakeSymbol(NameLinkQuery)
	SymLinkExternal    = sx.MakeSymbol(NameLinkExternal)

	SymListOrdered     = sx.MakeSymbol(NameListOrdered)
	SymListUnordered   = sx.MakeSymbol(NameListUnordered)
	SymListQuote       = sx.MakeSymbol(NameListQuote)
	SymLiteralProg     = sx.MakeSymbol(NameLiteralProg)
	SymLiteralComment  = sx.MakeSymbol(NameLiteralComment)
	SymLiteralHTML     = sx.MakeSymbol(NameLiteralHTML)
	SymLiteralInput    = sx.MakeSymbol(NameLiteralInput)



































	SymLiteralMath     = sx.MakeSymbol(NameLiteralMath)
	SymLiteralOutput   = sx.MakeSymbol(NameLiteralOutput)
	SymLiteralZettel   = sx.MakeSymbol(NameLiteralZettel)
	SymMark            = sx.MakeSymbol(NameMark)
	SymPara            = sx.MakeSymbol(NamePara)
	SymRegionBlock     = sx.MakeSymbol(NameRegionBlock)
	SymRegionQuote     = sx.MakeSymbol(NameRegionQuote)
	SymRegionVerse     = sx.MakeSymbol(NameRegionVerse)
	SymSoft            = sx.MakeSymbol(NameSoft)
	SymSpace           = sx.MakeSymbol(NameSpace)
	SymTable           = sx.MakeSymbol(NameTable)
	SymText            = sx.MakeSymbol(NameText)
	SymThematic        = sx.MakeSymbol(NameThematic)
	SymTransclude      = sx.MakeSymbol(NameTransclude)
	SymUnknown         = sx.MakeSymbol(NameUnknown)
	SymVerbatimComment = sx.MakeSymbol(NameVerbatimComment)
	SymVerbatimEval    = sx.MakeSymbol(NameVerbatimEval)
	SymVerbatimHTML    = sx.MakeSymbol(NameVerbatimHTML)
	SymVerbatimMath    = sx.MakeSymbol(NameVerbatimMath)
	SymVerbatimProg    = sx.MakeSymbol(NameVerbatimProg)
	SymVerbatimZettel  = sx.MakeSymbol(NameVerbatimZettel)










	// Constant symbols for reference states.
	SymRefStateInvalid  = sx.MakeSymbol(NameRefStateInvalid)
	SymRefStateZettel   = sx.MakeSymbol(NameRefStateZettel)
	SymRefStateSelf     = sx.MakeSymbol(NameRefStateSelf)
	SymRefStateFound    = sx.MakeSymbol(NameRefStateFound)
	SymRefStateBroken   = sx.MakeSymbol(NameRefStateBroken)
	SymRefStateHosted   = sx.MakeSymbol(NameRefStateHosted)
	SymRefStateBased    = sx.MakeSymbol(NameRefStateBased)
	SymRefStateQuery    = sx.MakeSymbol(NameRefStateQuery)
	SymRefStateExternal = sx.MakeSymbol(NameRefStateExternal)

	// Symbols for metadata types.
	SymTypeCredential   = sx.MakeSymbol(NameTypeCredential)
	SymTypeEmpty        = sx.MakeSymbol(NameTypeEmpty)
	SymTypeID           = sx.MakeSymbol(NameTypeID)
	SymTypeIDSet        = sx.MakeSymbol(NameTypeIDSet)
	SymTypeNumber       = sx.MakeSymbol(NameTypeNumber)
	SymTypeString       = sx.MakeSymbol(NameTypeString)
	SymTypeTagSet       = sx.MakeSymbol(NameTypeTagSet)
	SymTypeTimestamp    = sx.MakeSymbol(NameTypeTimestamp)
	SymTypeURL          = sx.MakeSymbol(NameTypeURL)
	SymTypeWord         = sx.MakeSymbol(NameTypeWord)

	SymTypeZettelmarkup = sx.MakeSymbol(NameTypeZettelmarkup)

)

//-----------------------------------------------------------------------------
// 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 sz

import (
	"zettelstore.de/client.fossil/attrs"
	"zettelstore.de/sx.fossil"

		val := pair.Cdr()
		if tail, isTailPair := sx.GetPair(val); isTailPair {
			val = tail.Car()
		}
		if !val.IsAtom() {
			continue
		}
		result = result.Set(GoValue(key), GoValue(val))
	}
	return result
}

// GoValue returns the string value of the sx.Object suitable for Go processing.
func GoValue(obj sx.Object) string {
	switch o := obj.(type) {
	case sx.String:
		return string(o)
	case *sx.Symbol:
		return o.GoString()
	}
	return obj.String()
}

// GetMetaContent returns the metadata and the content of a sz encoded zettel.
func GetMetaContent(zettel sx.Object) (Meta, *sx.Pair) {
	if pair, isPair := sx.GetPair(zettel); isPair {
		m := pair.Car()
		if s := pair.Tail(); s != nil {
			if content, isContentPair := sx.GetPair(s.Car()); isContentPair {

func MakeMeta(obj sx.Object) Meta {
	if result := doMakeMeta(obj); len(result) > 0 {
		return result
	}
	return nil
}
func doMakeMeta(obj sx.Object) Meta {





	lst, isList := sx.GetPair(obj)
	if !isList || !lst.Car().IsEqual(SymMeta) {
		return nil
	}
	result := make(map[string]MetaValue)
	for node := lst.Tail(); node != nil; node = node.Tail() {
		if mv, found := makeMetaValue(node.Head()); found {
			result[mv.Key] = mv
		}

	}





	return result




}

func makeMetaValue(mnode *sx.Pair) (MetaValue, bool) {
	var result MetaValue





	typeSym, isSymbol := sx.GetSymbol(mnode.Car())
	if !isSymbol {
		return result, false
	}
	next := mnode.Tail()
	keySym, isSymbol := sx.GetSymbol(next.Car())
	if !isSymbol {
		return result, false
	}

	next = next.Tail()


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

func (m Meta) GetString(key string) string {
	if v, found := m[key]; found {
		return GoValue(v.Value)
	}
	return ""
}

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
}

//-----------------------------------------------------------------------------
// 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 text provides types, constants and function to work with text output.
package text

import (
	"strings"

	"zettelstore.de/client.fossil/sz"
	"zettelstore.de/sx.fossil"
)

// Encoder is the structure to hold relevant data to execute the encoding.
type Encoder struct {

	sb strings.Builder
}







func NewEncoder() *Encoder {



	enc := &Encoder{

		sb: strings.Builder{},





	}
	return enc
}

func (enc *Encoder) Encode(lst *sx.Pair) string {
	enc.executeList(lst)
	result := enc.sb.String()
	enc.sb.Reset()
	return result
}

// EvaluateInlineString returns the text content of the given inline list as a string.
func EvaluateInlineString(lst *sx.Pair) string {

	return NewEncoder().Encode(lst)


}

func (enc *Encoder) executeList(lst *sx.Pair) {
	for elem := lst; elem != nil; elem = elem.Tail() {
		enc.execute(elem.Car())
	}
}
func (enc *Encoder) execute(obj sx.Object) {
	cmd, isPair := sx.GetPair(obj)
	if !isPair {
		return
	}
	sym := cmd.Car()
	if sx.IsNil(sym) {
		return
	}
	if sym.IsEqual(sz.SymText) {
		args := cmd.Tail()
		if args == nil {
			return
		}
		if val, isString := sx.GetString(args.Car()); isString {
			enc.sb.WriteString(string(val))
		}
	} else if sym.IsEqual(sz.SymSpace) || sym.IsEqual(sz.SymSoft) {
		enc.sb.WriteByte(' ')
	} else if sym.IsEqual(sz.SymHard) {
		enc.sb.WriteByte('\n')
	} else if !sym.IsEqual(sx.SymbolQuote) {
		enc.executeList(cmd.Tail())
	}
}

//-----------------------------------------------------------------------------
// 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 text_test

import (
	"strings"
	"testing"

<title>Change Log</title>

<a name="0_18"></a>
<h2>Changes for Version 0.18.0 (pending)</h2>

<a name="0_17"></a>
<h2>Changes for Version 0.17.0 (2024-03-04)</h2>
  *  Generic GET method for HTTP client.
  *  Adapt to sz changes; see manual for current syntax.
  *  Got some packages from Zettelstore, for general use.

<a name="0_16"></a>
<h2>Changes for Version 0.16.0 (2023-11-30)</h2>
  *  Refactor shtml transformator to support evaluating the language tree of a
     zettel AST. Its API has been changes, since evaluation is now top-down,
     where previous transformation was bottom.up.
  *  Add API call to retrieve role zettel.

<title>Home</title>

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

<h3>Latest Release: 0.17.0 (2024-03-04)</h3>
  *  [./changes.wiki#0_17|Change summary]
  *  [/timeline?p=v0.17.0&bt=v0.16.0&y=ci|Check-ins for version 0.17.0],
     [/vdiff?to=v0.17.0&from=v0.16.0|content diff]
  *  [/timeline?df=v0.17.0&y=ci|Check-ins derived from the 0.17.0 release],
     [/vdiff?from=v0.17.0&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