//-----------------------------------------------------------------------------
// 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 invalid 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
}

// ZettelMeta is a map containg the 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
	placeholder_1                // 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

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

	// 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

	ZidDeleteTemplate = ZettelID("00000000010405") // -> 000y
	ZidErrorTemplate  = ZettelID("00000000010700") // -> 000z

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

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

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

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

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

	// 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

	// 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

	ZidSession      = ZettelID("00009999999997") // -> 00zx
	ZidAppDirectory = ZettelID("00009999999998") // -> 00zy
	ZidDefaultHome  = ZettelID("00010000000000") // -> 0100
)

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

// Values of the metadata key/value type.
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
const (
	KeyID           = "id"
	KeyTitle        = "title"

	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"
	KeySummary      = "summary"
	KeySuperior     = "superior"

	KeyURL          = "url"
	KeyUselessFiles = "useless-files"
	KeyUserID       = "user-id"
	KeyUserRole     = "user-role"
	KeyVisibility   = "visibility"
)

	ValueVisibilityLogin   = "login"
	ValueVisibilityOwner   = "owner"
	ValueVisibilityPublic  = "public"
)

// Additional HTTP constants.
const (


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

// Values for HTTP query parameter.

// 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 "t73f.de/r/webs/urlbuilder"






// URLBuilder should be used to create zettelstore URLs.
type URLBuilder struct {
	base   urlbuilder.URLBuilder
	prefix string





}

// NewURLBuilder creates a new URL builder with the given prefix and key.
func NewURLBuilder(prefix string, key byte) *URLBuilder {
	for len(prefix) > 0 && prefix[len(prefix)-1] == '/' {
		prefix = prefix[0 : len(prefix)-1]
	}
	result := URLBuilder{prefix: prefix}
	if key != '/' {
		result.base.AddPath(string([]byte{key}))
	}
	return &result
}

// 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
func (ub *URLBuilder) AppendPath(p string) *URLBuilder {
	ub.base.AddPath(p)






	return ub
}

// 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
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
func (ub *URLBuilder) SetFragment(s string) *URLBuilder {

	ub.base.SetFragment(s)
	return ub
}

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








	return ub.prefix + ub.base.String()
























}

//-----------------------------------------------------------------------------
// 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 (
	"slices"
	"strings"

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

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

// IsEmpty returns true if there are no attributes.
func (a Attributes) IsEmpty() bool { return len(a) == 0 }

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

// Add a value to an attribute key.
func (a Attributes) Add(key, value string) Attributes {
	if a == nil {
		return map[string]string{key: value}
	}
	values := a.Values(key)
	if !slices.Contains(values, value) {
		values = append(values, value)
		a[key] = strings.Join(values, " ")
	}



	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)
		}



	}
	return nil
}

// Has the attribute key a value?
func (a Attributes) Has(key, value string) bool {

	return slices.Contains(a.Values(key), value)
}

// AddClass adds a value to the class attribute.

func (a Attributes) AddClass(class string) Attributes { return a.Add("class", class) }

// GetClasses returns the class values as a string slice
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) }

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

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

func TestHasDefault(t *testing.T) {
	t.Parallel()
	attr := attrs.Attributes{}
	if attr.HasDefault() {
		t.Error("Should not have default attr")

func TestHasClass(t *testing.T) {
	t.Parallel()
	testcases := []struct {
		classes string
		class   string
		exp     bool
	}{
		{"", "", 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},

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

	"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

	myURL := *u
	myURL.User = nil
	myURL.ForceQuery = false
	myURL.RawQuery = ""
	myURL.Fragment = ""
	myURL.RawFragment = ""
	base := myURL.String()



	c := Client{
		base: base,
		client: http.Client{
			Timeout: 10 * time.Second,
			Transport: &http.Transport{
				DialContext: (&net.Dialer{
					Timeout: 5 * time.Second, // TCP connect timeout

	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 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()
		}
		return nil, err
	}
	return resp, err
}

func (c *Client) buildAndExecuteRequest(
	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
	}



	return c.executeRequest(req)
}

// SetAuth sets authentication data.
func (c *Client) SetAuth(username, password string) {
	c.username = username
	c.password = password

	if err != nil {
		return err
	}
	vals, err := sexp.ParseList(obj, "ssi")
	if err != nil {
		return err
	}
	token := vals[1].(sx.String).GetValue()
	if len(token) < 4 {
		return fmt.Errorf("no valid token found: %q", token)
	}
	c.token = token
	c.tokenType = vals[0].(sx.String).GetValue()
	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))
	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)
	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)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	switch resp.StatusCode {
	case http.StatusOK:

		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)
	if err != nil {
		return "", "", nil, err
	}
	defer resp.Body.Close()
	rdr := sxreader.MakeReader(resp.Body)
	obj, err := rdr.Read()
	switch resp.StatusCode {

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

	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)
	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()

// 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)
	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)
	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 {

		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))
	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)

















	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)
	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)
	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)
	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)
	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"

	"t73f.de/r/zsc/api"

	"t73f.de/r/zsc/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 t73f.de/r/zsc

go 1.23

require (
	t73f.de/r/sx v0.0.0-20240814083626-4df0ec6454b5
	t73f.de/r/sxwebs v0.0.0-20240814085618-5b4b5c496c94
	t73f.de/r/webs v0.0.0-20240814085020-19dac746d568
)

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 v0.0.0-20240814085618-5b4b5c496c94 h1:gLneaEyYotvcY/dDznzdcSXK1RqsJVi2AfeYDc1iVwM=
t73f.de/r/sxwebs v0.0.0-20240814085618-5b4b5c496c94/go.mod h1:83W3QFkmrniIKv6R+Xq+imvbSolhoutTnNhW0ErJoco=
t73f.de/r/webs v0.0.0-20240814085020-19dac746d568 h1:Pa+vO2r++qhcShv0p7t/gIrJ1DHPMn4gopEXLxDmoRg=
t73f.de/r/webs v0.0.0-20240814085020-19dac746d568/go.mod h1:NSoOON8be62MfQZzlCApK27Jt2zhIa6Vrmo9RJ4tOnQ=

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

	"t73f.de/r/zsc/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 { return ch == EOS || ch == '\n' || ch == '\r' }

// 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()
	}
}

// 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
		}
		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"

	"t73f.de/r/zsc/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)
}

// 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

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"

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

func isSorted(seq []string) bool {
	for i := 1; i < len(seq); i++ {
		if seq[i] < seq[i-1] {
			return false
		}

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

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

// 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.MakeString(zettel.Encoding)),
		sx.MakeList(sx.MakeSymbol("content"), sx.MakeString(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: encVals[1].(sx.String).GetValue(),
		Content:  contentVals[1].(sx.String).GetValue(),
	}, 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.MakeString(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()] = mVals[1].(sx.String).GetValue()
	}
	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"

	"t73f.de/r/sx"
	"t73f.de/r/zsc/sexp"
)

func TestParseObject(t *testing.T) {
	if elems, err := sexp.ParseList(sx.MakeString("a"), "s"); err == nil {
		t.Error("expected an error, but got: ", elems)
	}
	if elems, err := sexp.ParseList(sx.Nil(), ""); err != nil {
		t.Error(err)
	} else if len(elems) != 0 {
		t.Error("Must be empty, but got:", elems)
	}
	if elems, err := sexp.ParseList(sx.Nil(), "b"); err == nil {
		t.Error("expected error, but got: ", elems)
	}

	if elems, err := sexp.ParseList(sx.MakeList(sx.MakeString("a")), "ss"); err == nil {
		t.Error("expected error, but got: ", elems)
	}
	if elems, err := sexp.ParseList(sx.MakeList(sx.MakeString("a")), ""); err == nil {
		t.Error("expected error, but got: ", elems)
	}
	if _, err := sexp.ParseList(sx.MakeList(sx.MakeString("a")), "b"); err != nil {
		t.Error("expected [1], but got error: ", err)
	}
	if elems, err := sexp.ParseList(sx.Cons(sx.Nil(), sx.MakeString("a")), "ps"); err == nil {
		t.Error("expected error, but got: ", elems)
	}

	if elems, err := sexp.ParseList(sx.MakeList(sx.MakeString("a")), "s"); err != nil {
		t.Error(err)
	} else if len(elems) != 1 {
		t.Error("length == 1, but got: ", elems)
	} else {
		_ = elems[0].(sx.String)
	}

//-----------------------------------------------------------------------------
// 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 "t73f.de/r/sx"

// 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")
	symTH         = sx.MakeSymbol("th")
	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

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[""]
}

//-----------------------------------------------------------------------------
// 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"
	"net/url"
	"strconv"
	"strings"

	"t73f.de/r/sx"
	"t73f.de/r/sxwebs/sxhtml"
	"t73f.de/r/zsc/api"
	"t73f.de/r/zsc/attrs"
	"t73f.de/r/zsc/sz"
	"t73f.de/r/zsc/text"
)

// 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 (ev *Evaluator) SetUnique(s string) { ev.unique = s }




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




// EvaluateAttrbute transforms the given attributes into a HTML s-expression.
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 && isValidName(key) {
			plist = plist.Cons(sx.Cons(sx.MakeSymbol(key), sx.MakeString(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 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))
	for i, fni := range env.endnotes {
		noteNum := strconv.Itoa(i + 1)
		attrs := fni.attrs.Cons(sx.Cons(SymAttrClass, sx.MakeString("zs-endnote"))).
			Cons(sx.Cons(SymAttrValue, sx.MakeString(noteNum))).
			Cons(sx.Cons(SymAttrId, sx.MakeString("fn:"+fni.noteID))).
			Cons(sx.Cons(SymAttrRole, sx.MakeString("doc-endnote"))).
			Cons(sxhtml.SymAttr)

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

		var li sx.ListBuilder
		li.Add(SymLI)
		li.Add(attrs)
		li.ExtendBang(fni.noteHx)
		li.Add(sx.MakeString(" "))
		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    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 {


	return Environment{
		err:          nil,
		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.Reset()
	env.endnotes = nil
	env.quoteNesting = 0
}

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

// popAttributes removes the current attributes from the envrionment.
func (env *Environment) popAttributes() { env.langStack.Pop() }



// 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
	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", 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)
	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(getString(elem.Car(), env).GetValue())
		}
		s := sb.String()
		if len(s) > 0 {
			s = s[1:]
		}
		a := make(attrs.Attributes, 2).
			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", 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(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 heading level", nLevel)
			return sx.Nil()
		}
		level := strconv.FormatInt(nLevel+ev.headingOffset, 10)
		headingSymbol := sx.MakeSymbol("h" + level)

		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(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(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(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(symTD, 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 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 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 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 := GetAttributes(args[0], env)
		content := getString(args[1], env)
		if a.HasDefault() {
			content = sx.MakeString(visibleReplacer.Replace(content.GetValue()))
		}
		return evalVerbatim(a, content)
	})
	ev.bind(sz.SymVerbatimZettel, 0, nilFn)
	ev.bind(sz.SymBLOB, 3, func(args sx.Vector, env *Environment) sx.Object {
		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.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,
			)
		}
		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(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(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(EvaluateAttrbute(attrs.Attributes{"class": align}))
		}
		return tdata
	}
}

func (ev *Evaluator) makeRegionFn(sym *sx.Symbol, genericToClass bool) EvalFn {
	return func(args sx.Vector, env *Environment) sx.Object {
		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(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 evalVerbatim(a attrs.Attributes, s sx.String) sx.Object {
	a = setProgLang(a)
	code := sx.Nil().Cons(s)
	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 := 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 := 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 := 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 := 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 := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		refValue := getString(args[1], 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)















		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, EvaluateAttrbute(a))
	})
	ev.bind(sz.SymEmbedBLOB, 3, func(args sx.Vector, env *Environment) sx.Object {
		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 evalBLOB(
			sx.MakeList(sxhtml.SymListSplice, sx.MakeString(summary)),
			syntax,
			data,
		)
	})

	ev.bind(sz.SymCite, 2, func(args sx.Vector, env *Environment) sx.Object {
		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(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(EvaluateAttrbute(a)).Cons(SymA)
			}
		}
		return result.Cons(SymSPAN)
	})
	ev.bind(sz.SymEndnote, 1, func(args sx.Vector, env *Environment) sx.Object {
		a := GetAttributes(args[0], env)
		env.pushAttributes(a)
		defer env.popAttributes()
		attrPlist := sx.Nil()
		if len(a) > 0 {
			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{
			noteID: noteID, noteAST: args[1:], noteHx: nil, attrs: attrPlist})
		hrefAttr := sx.Nil().Cons(sx.Cons(SymAttrRole, sx.MakeString("doc-noteref"))).
			Cons(sx.Cons(SymAttrHref, sx.MakeString("#fn:"+noteID))).
			Cons(sx.Cons(SymAttrClass, sx.MakeString("zs-noteref"))).
			Cons(sxhtml.SymAttr)
		href := sx.Nil().Cons(sx.MakeString(noteNum)).Cons(hrefAttr).Cons(SymA)
		supAttr := sx.Nil().Cons(sx.Cons(SymAttrId, sx.MakeString("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 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 evalLiteral(args, nil, symKBD, env)
	})

	ev.bind(sz.SymLiteralMath, 2, func(args sx.Vector, env *Environment) sx.Object {
		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 evalLiteral(args, nil, symSAMP, env)
	})
	ev.bind(sz.SymLiteralProg, 2, func(args sx.Vector, env *Environment) sx.Object {
		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 := 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(EvaluateAttrbute(a))
		}
		return res.Cons(sym)
	}
}


































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

	if val, hasClass := a.Get(""); hasClass {
		a = a.Remove("").AddClass(val)
	}

	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 withNbsp {
			lastPair.AppendBang(sx.MakeList(sxhtml.SymNoEscape, sx.MakeString("&nbsp;"), sx.MakeString(rightQ)))
			res = res.Cons(sx.MakeList(sxhtml.SymNoEscape, sx.MakeString(leftQ), sx.MakeString("&nbsp;")))
		} 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(EvaluateAttrbute(a))
		return res.Cons(SymSPAN)
	}
	return res.Cons(sxhtml.SymListSplice)
}

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

func evalLiteral(args sx.Vector, a attrs.Attributes, sym *sx.Symbol, env *Environment) sx.Object {
	if a == nil {
		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(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 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:
		return sx.Nil().Cons(sx.Nil().Cons(data).Cons(sxhtml.SymNoEscape)).Cons(SymP)
	default:
		imgAttr := sx.Nil().Cons(sx.Cons(SymAttrSrc, sx.MakeString("data:image/"+syntax.GetValue()+";base64,"+data.GetValue())))
		var sb strings.Builder
		flattenText(&sb, description)
		if d := sb.String(); d != "" {
			imgAttr = imgAttr.Cons(sx.Cons(symAttrAlt, sx.MakeString(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(obj.GetValue())





		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(EvaluateAttrbute(a)).Cons(SymA)
}

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("???")
}
func getString(val sx.Object, env *Environment) sx.String {
	if env.err != nil {
		return sx.String{}
	}
	if s, ok := sx.GetString(val); ok {
		return s
	}
	env.err = fmt.Errorf("%v/%T is not a string", val, val)
	return sx.String{}
}
func getList(val sx.Object, env *Environment) *sx.Pair {
	if env.err == nil {
		if res, isPair := sx.GetPair(val); isPair {
			return res
		}
		env.err = fmt.Errorf("%v/%T is not a list", val, val)
	}
	return nil
}
func getInt64(val sx.Object, env *Environment) int64 {
	if env.err != nil {
		return -1017
	}
	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 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 "t73f.de/r/sx"

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

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








































































	// Symbols for Zettel noMakede types.

	SymBLOB            = sx.MakeSymbol("BLOB")
	SymCell            = sx.MakeSymbol("CELL")
	SymCellCenter      = sx.MakeSymbol("CELL-CENTER")
	SymCellLeft        = sx.MakeSymbol("CELL-LEFT")
	SymCellRight       = sx.MakeSymbol("CELL-RIGHT")
	SymCite            = sx.MakeSymbol("CITE")
	SymDescription     = sx.MakeSymbol("DESCRIPTION")
	SymEmbed           = sx.MakeSymbol("EMBED")
	SymEmbedBLOB       = sx.MakeSymbol("EMBED-BLOB")
	SymEndnote         = sx.MakeSymbol("ENDNOTE")


	SymFormatEmph      = sx.MakeSymbol("FORMAT-EMPH")



	SymFormatDelete    = sx.MakeSymbol("FORMAT-DELETE")


















	SymFormatInsert    = sx.MakeSymbol("FORMAT-INSERT")
	SymFormatMark      = sx.MakeSymbol("FORMAT-MARK")
	SymFormatQuote     = sx.MakeSymbol("FORMAT-QUOTE")
	SymFormatSpan      = sx.MakeSymbol("FORMAT-SPAN")
	SymFormatSub       = sx.MakeSymbol("FORMAT-SUB")
	SymFormatSuper     = sx.MakeSymbol("FORMAT-SUPER")
	SymFormatStrong    = sx.MakeSymbol("FORMAT-STRONG")
	SymHard            = sx.MakeSymbol("HARD")
	SymHeading         = sx.MakeSymbol("HEADING")
	SymLinkInvalid     = sx.MakeSymbol("LINK-INVALID")
	SymLinkZettel      = sx.MakeSymbol("LINK-ZETTEL")
	SymLinkSelf        = sx.MakeSymbol("LINK-SELF")
	SymLinkFound       = sx.MakeSymbol("LINK-FOUND")
	SymLinkBroken      = sx.MakeSymbol("LINK-BROKEN")
	SymLinkHosted      = sx.MakeSymbol("LINK-HOSTED")
	SymLinkBased       = sx.MakeSymbol("LINK-BASED")
	SymLinkQuery       = sx.MakeSymbol("LINK-QUERY")
	SymLinkExternal    = sx.MakeSymbol("LINK-EXTERNAL")
	SymListOrdered     = sx.MakeSymbol("ORDERED")
	SymListUnordered   = sx.MakeSymbol("UNORDERED")
	SymListQuote       = sx.MakeSymbol("QUOTATION")
	SymLiteralProg     = sx.MakeSymbol("LITERAL-CODE")
	SymLiteralComment  = sx.MakeSymbol("LITERAL-COMMENT")
	SymLiteralHTML     = sx.MakeSymbol("LITERAL-HTML")
	SymLiteralInput    = sx.MakeSymbol("LITERAL-INPUT")
	SymLiteralMath     = sx.MakeSymbol("LITERAL-MATH")
	SymLiteralOutput   = sx.MakeSymbol("LITERAL-OUTPUT")
	SymLiteralZettel   = sx.MakeSymbol("LITERAL-ZETTEL")
	SymMark            = sx.MakeSymbol("MARK")





















































	SymPara            = sx.MakeSymbol("PARA")











































	SymRegionBlock     = sx.MakeSymbol("REGION-BLOCK")
	SymRegionQuote     = sx.MakeSymbol("REGION-QUOTE")
	SymRegionVerse     = sx.MakeSymbol("REGION-VERSE")
	SymSoft            = sx.MakeSymbol("SOFT")

	SymTable           = sx.MakeSymbol("TABLE")
	SymText            = sx.MakeSymbol("TEXT")
	SymThematic        = sx.MakeSymbol("THEMATIC")
	SymTransclude      = sx.MakeSymbol("TRANSCLUDE")
	SymUnknown         = sx.MakeSymbol("UNKNOWN-NODE")
	SymVerbatimComment = sx.MakeSymbol("VERBATIM-COMMENT")
	SymVerbatimEval    = sx.MakeSymbol("VERBATIM-EVAL")
	SymVerbatimHTML    = sx.MakeSymbol("VERBATIM-HTML")
	SymVerbatimMath    = sx.MakeSymbol("VERBATIM-MATH")
	SymVerbatimProg    = sx.MakeSymbol("VERBATIM-CODE")
	SymVerbatimZettel  = sx.MakeSymbol("VERBATIM-ZETTEL")

	// Constant symbols for reference states.
	SymRefStateInvalid  = sx.MakeSymbol("INVALID")
	SymRefStateZettel   = sx.MakeSymbol("ZETTEL")
	SymRefStateSelf     = sx.MakeSymbol("SELF")
	SymRefStateFound    = sx.MakeSymbol("FOUND")
	SymRefStateBroken   = sx.MakeSymbol("BROKEN")
	SymRefStateHosted   = sx.MakeSymbol("HOSTED")
	SymRefStateBased    = sx.MakeSymbol("BASED")
	SymRefStateQuery    = sx.MakeSymbol("QUERY")
	SymRefStateExternal = sx.MakeSymbol("EXTERNAL")

	// Symbols for metadata types.
	SymTypeCredential   = sx.MakeSymbol("CREDENTIAL")
	SymTypeEmpty        = sx.MakeSymbol("EMPTY-STRING")
	SymTypeID           = sx.MakeSymbol("ZID")
	SymTypeIDSet        = sx.MakeSymbol("ZID-SET")
	SymTypeNumber       = sx.MakeSymbol("NUMBER")
	SymTypeString       = sx.MakeSymbol("STRING")
	SymTypeTagSet       = sx.MakeSymbol("TAG-SET")
	SymTypeTimestamp    = sx.MakeSymbol("TIMESTAMP")
	SymTypeURL          = sx.MakeSymbol("URL")
	SymTypeWord         = sx.MakeSymbol("WORD")

	SymTypeZettelmarkup = sx.MakeSymbol("ZETTELMARKUP")
)

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

import (
	"t73f.de/r/sx"
	"t73f.de/r/zsc/api"
	"t73f.de/r/zsc/input"
)

// --- Contains some simple parsers

// ---- Syntax: none

// ParseNoneBlocks parses no block.
func ParseNoneBlocks(*input.Input) *sx.Pair { return nil }

// ParseNoneInlines skips to the end of line and parses no inline.
func ParseNoneInlines(inp *input.Input) *sx.Pair {
	inp.SkipToEOL()
	return nil
}

// ---- Some plain text syntaxes

// ParsePlainBlocks parses the block as plain text with the given syntax.
func ParsePlainBlocks(inp *input.Input, syntax string) *sx.Pair {
	var sym *sx.Symbol
	if syntax == api.ValueSyntaxHTML {
		sym = SymVerbatimHTML
	} else {
		sym = SymVerbatimProg
	}
	return sx.MakeList(
		sym,
		sx.MakeList(sx.Cons(sx.MakeString(""), sx.MakeString(syntax))),
		sx.MakeString(string(inp.ScanLineContent())),
	)
}

// ParsePlainInlines parses the inline as plain text with the given syntax.
func ParsePlainInlines(inp *input.Input, syntax string) *sx.Pair {
	var sym *sx.Symbol
	if syntax == api.ValueSyntaxHTML {
		sym = SymLiteralHTML
	} else {
		sym = SymLiteralProg
	}
	pos := inp.Pos
	inp.SkipToEOL()
	return sx.MakeList(
		sym,
		sx.MakeList(sx.Cons(sx.MakeString(""), sx.MakeString(syntax))),
		sx.MakeString(string(inp.Src[pos:inp.Pos])),
	)
}

//-----------------------------------------------------------------------------
// 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 sz_test

import (
	"testing"

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

func TestParseNone(t *testing.T) {
	if got := sz.ParseNoneBlocks(nil); got != nil {
		t.Error("GOTB", got)
	}

	inp := input.NewInput([]byte("1234\n6789"))
	if got := sz.ParseNoneInlines(inp); got != nil {
		t.Error("GOTI", got)
	}
	if got := inp.Pos; got != 4 {
		t.Errorf("input should be on position 4, but is %d", got)
	}
	if got := inp.Ch; got != '\n' {
		t.Errorf("input character should be 10, but is %d", got)
	}
}

func TestParsePlani(t *testing.T) {
	testcases := []struct {
		src        string
		syntax     string
		expBlocks  string
		expInlines string
	}{
		{"abc", "html",
			"(VERBATIM-HTML ((\"\" . \"html\")) \"abc\")",
			"(LITERAL-HTML ((\"\" . \"html\")) \"abc\")"},
		{"abc\ndef", "html",
			"(VERBATIM-HTML ((\"\" . \"html\")) \"abc\\ndef\")",
			"(LITERAL-HTML ((\"\" . \"html\")) \"abc\")"},
		{"abc", "text",
			"(VERBATIM-CODE ((\"\" . \"text\")) \"abc\")",
			"(LITERAL-CODE ((\"\" . \"text\")) \"abc\")"},
		{"abc\nDEF", "text",
			"(VERBATIM-CODE ((\"\" . \"text\")) \"abc\\nDEF\")",
			"(LITERAL-CODE ((\"\" . \"text\")) \"abc\")"},
	}
	for i, tc := range testcases {
		t.Run(tc.syntax+":"+tc.src, func(t *testing.T) {
			inp := input.NewInput([]byte(tc.src))
			if got := sz.ParsePlainBlocks(inp, tc.syntax).String(); tc.expBlocks != got {
				t.Errorf("%d: %q/%v\nexpected: %q\ngot     : %q", i, tc.src, tc.syntax, tc.expBlocks, got)
			}
			inp.SetPos(0)
			if got := sz.ParsePlainInlines(inp, tc.syntax).String(); tc.expInlines != got {
				t.Errorf("%d: %q/%v\nexpected: %q\ngot     : %q", i, tc.src, tc.syntax, tc.expInlines, got)
			}
		})
	}
}

//-----------------------------------------------------------------------------
// 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 contains zettel data handling as sx expressions.
package sz

import (
	"t73f.de/r/sx"
	"t73f.de/r/zsc/attrs"
)

// GetAttributes traverses a s-expression list and returns an attribute structure.
func GetAttributes(seq *sx.Pair) (result attrs.Attributes) {
	for elem := seq; elem != nil; elem = elem.Tail() {
		pair, isPair := sx.GetPair(elem.Car())
		if !isPair || pair == nil {
			continue
		}
		key := pair.Car()
		if !key.IsAtom() {
			continue
		}
		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 o.GetValue()
	case *sx.Symbol:
		return o.GetValue()
	}
	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 {
				return MakeMeta(m), content

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
}

// MapRefStateToLinkEmbed maps a reference state symbol to a link symbol or to
// an embed symbol, depending on 'forLink'.
func MapRefStateToLinkEmbed(symRefState *sx.Symbol, forLink bool) *sx.Symbol {
	if !forLink {
		return SymEmbed
	}
	if sym, found := mapRefStateLink[symRefState]; found {
		return sym
	}
	return SymLinkInvalid
}

var mapRefStateLink = map[*sx.Symbol]*sx.Symbol{
	SymRefStateInvalid:  SymLinkInvalid,
	SymRefStateZettel:   SymLinkZettel,
	SymRefStateSelf:     SymLinkSelf,
	SymRefStateFound:    SymLinkFound,
	SymRefStateBroken:   SymLinkBroken,
	SymRefStateHosted:   SymLinkHosted,
	SymRefStateBased:    SymLinkBased,
	SymRefStateQuery:    SymLinkQuery,
	SymRefStateExternal: SymLinkExternal,
}

// IsBreakSym return true if the object is either a soft or a hard break symbol.
func IsBreakSym(obj sx.Object) bool {
	return SymSoft.IsEqual(obj) || SymHard.IsEqual(obj)
}

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

import "t73f.de/r/sx"

// Visitor is walking the sx-based AST.
type Visitor interface {
	Visit(node *sx.Pair, env *sx.Pair) sx.Object
}

// Walk a sx-based AST through a Visitor.
func Walk(v Visitor, node *sx.Pair, env *sx.Pair) *sx.Pair {
	if node == nil {
		return nil
	}
	if result, isPair := sx.GetPair(v.Visit(node, env)); isPair {
		return result
	}

	if sym, isSymbol := sx.GetSymbol(node.Car()); isSymbol {
		if fn, found := mapChildrenWalk[sym]; found {
			return fn(v, node, env)
		}
		return node
	}
	panic(node)
}

var mapChildrenWalk map[*sx.Symbol]func(Visitor, *sx.Pair, *sx.Pair) *sx.Pair

func init() {
	mapChildrenWalk = map[*sx.Symbol]func(Visitor, *sx.Pair, *sx.Pair) *sx.Pair{
		SymBlock:         walkChildrenTail,
		SymPara:          walkChildrenTail,
		SymRegionBlock:   walkChildrenRegion,
		SymRegionQuote:   walkChildrenRegion,
		SymRegionVerse:   walkChildrenRegion,
		SymHeading:       walkChildrenHeading,
		SymListOrdered:   walkChildrenTail,
		SymListUnordered: walkChildrenTail,
		SymListQuote:     walkChildrenTail,
		SymDescription:   walkChildrenDescription,
		SymTable:         walkChildrenTable,

		SymInline:       walkChildrenTail,
		SymEndnote:      walkChildrenInlines3,
		SymMark:         walkChildrenMark,
		SymLinkBased:    walkChildrenInlines4,
		SymLinkBroken:   walkChildrenInlines4,
		SymLinkExternal: walkChildrenInlines4,
		SymLinkFound:    walkChildrenInlines4,
		SymLinkHosted:   walkChildrenInlines4,
		SymLinkInvalid:  walkChildrenInlines4,
		SymLinkQuery:    walkChildrenInlines4,
		SymLinkSelf:     walkChildrenInlines4,
		SymLinkZettel:   walkChildrenInlines4,
		SymEmbed:        walkChildrenEmbed,
		SymCite:         walkChildrenInlines4,
		SymFormatDelete: walkChildrenInlines3,
		SymFormatEmph:   walkChildrenInlines3,
		SymFormatInsert: walkChildrenInlines3,
		SymFormatMark:   walkChildrenInlines3,
		SymFormatQuote:  walkChildrenInlines3,
		SymFormatStrong: walkChildrenInlines3,
		SymFormatSpan:   walkChildrenInlines3,
		SymFormatSub:    walkChildrenInlines3,
		SymFormatSuper:  walkChildrenInlines3,
	}
}

func walkChildrenTail(v Visitor, node *sx.Pair, env *sx.Pair) *sx.Pair {
	hasNil := false
	for n := node.Tail(); n != nil; n = n.Tail() {
		obj := Walk(v, n.Head(), env)
		if sx.IsNil(obj) {
			hasNil = true
		}
		n.SetCar(obj)
	}
	if !hasNil {
		return node
	}
	for n := node; ; {
		next := n.Tail()
		if next == nil {
			break
		}
		if sx.IsNil(next.Car()) {
			n.SetCdr(next.Cdr())
			continue
		}
		n = next
	}
	return node
}

func walkChildrenList(v Visitor, lst *sx.Pair, env *sx.Pair) *sx.Pair {
	hasNil := false
	for n := lst; n != nil; n = n.Tail() {
		obj := Walk(v, n.Head(), env)
		if sx.IsNil(obj) {
			hasNil = true
		}
		n.SetCar(obj)
	}
	if !hasNil {
		return lst
	}
	var result sx.ListBuilder
	for n := lst; n != nil; n = n.Tail() {
		obj := n.Car()
		if !sx.IsNil(obj) {
			result.Add(obj)
		}
	}
	return result.List()
}

func walkChildrenRegion(v Visitor, node *sx.Pair, env *sx.Pair) *sx.Pair {
	// sym := node.Car()
	next := node.Tail()
	// attrs := next.Car()
	next = next.Tail()
	next.SetCar(walkChildrenList(v, next.Head(), env))
	next.SetCdr(walkChildrenList(v, next.Tail(), env))
	return node
}

func walkChildrenHeading(v Visitor, node *sx.Pair, env *sx.Pair) *sx.Pair {
	// sym := node.Car()
	next := node.Tail()
	// level := next.Car()
	next = next.Tail()
	// attrs := next.Car()
	next = next.Tail()
	// slug := next.Car()
	next = next.Tail()
	// fragment := next.Car()
	next.SetCdr(walkChildrenList(v, next.Tail(), env))
	return node
}

func walkChildrenDescription(v Visitor, dn *sx.Pair, env *sx.Pair) *sx.Pair {
	for n := dn.Tail(); n != nil; n = n.Tail() {
		n.SetCar(walkChildrenList(v, n.Head(), env))
		n = n.Tail()
		if n == nil {
			break
		}
		n.SetCar(Walk(v, n.Head(), env))
	}
	return dn
}

func walkChildrenTable(v Visitor, tn *sx.Pair, env *sx.Pair) *sx.Pair {
	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()
	next.SetCdr(walkChildrenList(v, next.Tail(), env))
	return ln
}

func walkChildrenInlines3(v Visitor, node *sx.Pair, env *sx.Pair) *sx.Pair {
	// sym := node.Car()
	next := node.Tail() // Attrs
	// attrs := next.Car()
	next.SetCdr(walkChildrenList(v, next.Tail(), env))
	return node
}

//-----------------------------------------------------------------------------
// 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 (
	"fmt"

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

// parseBlock parses one block.
func (cp *zmkP) parseBlock(lastPara *sx.Pair) (res *sx.Pair, cont bool) {
	inp := cp.inp
	pos := inp.Pos
	if cp.nestingLevel <= maxNestingLevel {
		cp.nestingLevel++
		defer func() { cp.nestingLevel-- }()

		var bn *sx.Pair
		success := false

		switch inp.Ch {
		case input.EOS:
			return nil, false
		case '\n', '\r':
			inp.EatEOL()
			cp.cleanupListsAfterEOL()
			return nil, false
		case ':':
			bn, success = cp.parseColon()
		case '@', '`', runeModGrave, '%', '~', '$':
			cp.clearStacked()
			bn, success = cp.parseVerbatim()
		case '"', '<':
			cp.clearStacked()
			bn, success = cp.parseRegion()
		case '=':
			cp.clearStacked()
			bn, success = cp.parseHeading()
		case '-':
			cp.clearStacked()
			bn, success = cp.parseHRule()
		case '*', '#', '>':
			cp.lastRow = nil
			cp.descrl = nil
			bn, success = cp.parseNestedList()
		case ';':
			cp.lists = nil
			cp.lastRow = nil
			bn, success = cp.parseDefTerm()
		case ' ':
			cp.lastRow = nil
			bn, success = nil, cp.parseIndent()
		case '|':
			cp.lists = nil
			cp.descrl = nil
			bn, success = cp.parseRow(), true
		case '{':
			cp.clearStacked()
			bn, success = cp.parseTransclusion()
		}

		if success {
			return bn, false
		}
	}
	inp.SetPos(pos)
	cp.clearStacked()
	ins := cp.parsePara()
	if startsWithSpaceSoftBreak(ins) {
		ins = ins[2:]
	} else if lastPara != nil {
		lastPair := lastPara.LastPair()
		lastPair.ExtendBang(sx.MakeList(ins...))
		return nil, true
	}
	return sx.MakeList(ins...).Cons(sz.SymPara), false
}

func startsWithSpaceSoftBreak(ins sx.Vector) bool {
	if len(ins) < 2 {
		return false
	}
	pair0, isPair0 := sx.GetPair(ins[0])
	pair1, isPair1 := sx.GetPair(ins[0])
	if !isPair0 || !isPair1 {
		return false
	}
	if pair0.Car().IsEqual(sz.SymText) && sz.IsBreakSym(pair1.Car()) {
		if args := pair0.Tail(); args != nil {
			if val, isString := sx.GetString(args.Car()); isString {
				for _, ch := range val.GetValue() {
					if !input.IsSpace(ch) {
						return false
					}
				}
				return true
			}
		}
	}
	return false
}

var symSeparator = sx.MakeSymbol("sEpArAtOr")

func (cp *zmkP) cleanupListsAfterEOL() {
	for _, l := range cp.lists {
		l.LastPair().Head().LastPair().AppendBang(sx.Cons(symSeparator, nil))
	}
	if descrl := cp.descrl; descrl != nil {
		if lastPair, pos := lastPairPos(descrl); pos > 1 && pos%2 == 0 {
			lastPair.Head().LastPair().AppendBang(sx.Cons(symSeparator, nil))
		}
	}
}

// parseColon determines which element should be parsed.
func (cp *zmkP) parseColon() (*sx.Pair, bool) {
	inp := cp.inp
	if inp.PeekN(1) == ':' {
		cp.clearStacked()
		return cp.parseRegion()
	}
	return cp.parseDefDescr()
}

// parsePara parses paragraphed inline material as a sx.Vector.
func (cp *zmkP) parsePara() (result sx.Vector) {
	for {
		in := cp.parseInline()
		if in == nil {
			return result
		}
		result = append(result, in)
		if sz.IsBreakSym(in.Car()) {
			ch := cp.inp.Ch
			switch ch {
			// Must contain all cases from above switch in parseBlock.
			case input.EOS, '\n', '\r', '@', '`', runeModGrave, '%', '~', '$', '"', '<', '=', '-', '*', '#', '>', ';', ':', ' ', '|', '{':
				return result
			}
		}
	}
}

// countDelim read from input until a non-delimiter is found and returns number of delimiter chars.
func (cp *zmkP) countDelim(delim rune) int {
	inp := cp.inp
	cnt := 0
	for inp.Ch == delim {
		cnt++
		inp.Next()
	}
	return cnt
}

// parseVerbatim parses a verbatim block.
func (cp *zmkP) parseVerbatim() (rn *sx.Pair, success bool) {
	inp := cp.inp
	fch := inp.Ch
	cnt := cp.countDelim(fch)
	if cnt < 3 {
		return nil, false
	}
	attrs := cp.parseBlockAttributes()
	inp.SkipToEOL()
	if inp.Ch == input.EOS {
		return nil, false
	}
	var sym *sx.Symbol
	switch fch {
	case '@':
		sym = sz.SymVerbatimZettel
	case '`', runeModGrave:
		sym = sz.SymVerbatimProg
	case '%':
		sym = sz.SymVerbatimComment
	case '~':
		sym = sz.SymVerbatimEval
	case '$':
		sym = sz.SymVerbatimMath
	default:
		panic(fmt.Sprintf("%q is not a verbatim char", fch))
	}
	content := make([]byte, 0, 512)
	for {
		inp.EatEOL()
		posL := inp.Pos
		switch inp.Ch {
		case fch:
			if cp.countDelim(fch) >= cnt {
				inp.SkipToEOL()
				rn = sx.MakeList(sym, attrs, sx.MakeString(string(content)))
				return rn, true
			}
			inp.SetPos(posL)
		case input.EOS:
			return nil, false
		}
		inp.SkipToEOL()
		if len(content) > 0 {
			content = append(content, '\n')
		}
		content = append(content, inp.Src[posL:inp.Pos]...)
	}
}

// parseRegion parses a block region.
func (cp *zmkP) parseRegion() (rn *sx.Pair, success bool) {
	inp := cp.inp
	fch := inp.Ch
	cnt := cp.countDelim(fch)
	if cnt < 3 {
		return nil, false
	}

	var sym *sx.Symbol
	oldInVerse := cp.inVerse
	defer func() { cp.inVerse = oldInVerse }()
	switch fch {
	case ':':
		sym = sz.SymRegionBlock
	case '<':
		sym = sz.SymRegionQuote
	case '"':
		sym = sz.SymRegionVerse
		cp.inVerse = true
	default:
		panic(fmt.Sprintf("%q is not a region char", fch))
	}
	attrs := cp.parseBlockAttributes()
	inp.SkipToEOL()
	if inp.Ch == input.EOS {
		return nil, false
	}
	var blocksBuilder sx.ListBuilder
	var lastPara *sx.Pair
	inp.EatEOL()
	for {
		posL := inp.Pos
		switch inp.Ch {
		case fch:
			if cp.countDelim(fch) >= cnt {
				ins := cp.parseRegionLastLine()
				rn = ins.Cons(blocksBuilder.List()).Cons(attrs).Cons(sym)
				return rn, true
			}
			inp.SetPos(posL)
		case input.EOS:
			return nil, false
		}
		bn, cont := cp.parseBlock(lastPara)
		if bn != nil {
			blocksBuilder.Add(bn)
		}
		if !cont {
			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
	inp.SkipSpace()
	var region sx.ListBuilder
	for {
		switch inp.Ch {
		case input.EOS, '\n', '\r':
			return region.List()
		}
		in := cp.parseInline()
		if in == nil {
			return region.List()
		}
		region.Add(in)
	}
}

// parseHeading parses a head line.
func (cp *zmkP) parseHeading() (hn *sx.Pair, success bool) {
	inp := cp.inp
	delims := cp.countDelim(inp.Ch)
	if delims < 3 {
		return nil, false
	}
	if inp.Ch != ' ' {
		return nil, false
	}
	inp.Next()
	inp.SkipSpace()
	if delims > 7 {
		delims = 7
	}
	level := int64(delims - 2)
	var attrs *sx.Pair
	var text sx.ListBuilder
	for {
		if input.IsEOLEOS(inp.Ch) {
			return createHeading(level, attrs, text.List()), true
		}
		in := cp.parseInline()
		if in == nil {
			return createHeading(level, attrs, text.List()), true
		}
		text.Add(in)
		if inp.Ch == '{' && inp.Peek() != '{' {
			attrs = cp.parseBlockAttributes()
			inp.SkipToEOL()
			return createHeading(level, attrs, text.List()), true
		}
	}
}
func createHeading(level int64, attrs, text *sx.Pair) *sx.Pair {
	return text.
		Cons(sx.MakeString("")). // Fragment
		Cons(sx.MakeString("")). // Slug
		Cons(attrs).
		Cons(sx.Int64(level)).
		Cons(sz.SymHeading)
}

// parseHRule parses a horizontal rule.
func (cp *zmkP) parseHRule() (hn *sx.Pair, success bool) {
	inp := cp.inp
	if cp.countDelim(inp.Ch) < 3 {
		return nil, false
	}

	attrs := cp.parseBlockAttributes()
	inp.SkipToEOL()
	return sx.MakeList(sz.SymThematic, attrs), true
}

// 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
	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)
	pv := cp.parseLinePara()
	bn := sx.Cons(sz.SymBlock, nil)
	if len(pv) != 0 {
		bn.AppendBang(pv.MakeList().Cons(sz.SymPara))
	}
	lastItemPair := ln.LastPair()
	lastItemPair.AppendBang(bn)
	return cp.cleanupParsedNestedList(newLnCount)
}

func (cp *zmkP) parseNestedListKinds() []*sx.Symbol {
	inp := cp.inp
	result := make([]*sx.Symbol, 0, 8)
	for {
		var sym *sx.Symbol
		switch inp.Ch {
		case '*':
			sym = sz.SymListUnordered
		case '#':
			sym = sz.SymListOrdered
		case '>':
			sym = sz.SymListQuote
		default:
			panic(fmt.Sprintf("%q is not a region char", inp.Ch))
		}
		result = append(result, sym)
		switch inp.Next() {
		case '*', '#', '>':
		case ' ', input.EOS, '\n', '\r':
			return result
		default:
			return nil
		}
	}
}

func (cp *zmkP) buildNestedList(kinds []*sx.Symbol) (ln *sx.Pair, newLnCount int) {
	for i, kind := range kinds {
		if i < len(cp.lists) {
			if !cp.lists[i].Car().IsEqual(kind) {
				ln = sx.Cons(kind, nil)
				newLnCount++
				cp.lists[i] = ln
				cp.lists = cp.lists[:i+1]
			} else {
				ln = cp.lists[i]
			}
		} else {
			ln = sx.Cons(kind, nil)
			newLnCount++
			cp.lists = append(cp.lists, ln)
		}
	}
	return ln, newLnCount
}

func (cp *zmkP) cleanupParsedNestedList(newLnCount int) (res *sx.Pair, success bool) {
	childPos := len(cp.lists) - 1
	parentPos := childPos - 1
	for i := 0; i < newLnCount; i++ {
		if parentPos < 0 {
			return cp.lists[0], true
		}
		parentLn := cp.lists[parentPos]
		childLn := cp.lists[childPos]
		if firstParent := parentLn.Tail(); firstParent != nil {
			// Add list to last item of the parent list
			lastParent := firstParent.LastPair()
			lastParent.Head().LastPair().AppendBang(childLn)
		} else {
			// Set list to first child of parent.
			childBlock := sx.MakeList(sz.SymBlock, cp.lists[childPos])
			parentLn.LastPair().AppendBang(childBlock)
		}
		childPos--
		parentPos--
	}
	return nil, true
}

// 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()
	inp.SkipSpace()
	descrl := cp.descrl
	if descrl == nil {
		descrl = sx.Cons(sz.SymDescription, nil)
		cp.descrl = descrl
		res = descrl
	}
	lastPair, pos := lastPairPos(descrl)
	for {
		in := cp.parseInline()
		if in == nil {
			if pos%2 == 0 {
				// lastPair is either the empty description list or the last block of definitions
				return nil, false
			}
			// lastPair is the definition term
			return res, true
		}
		if pos%2 == 0 {
			// lastPair is either the empty description list or the last block of definitions
			lastPair = lastPair.AppendBang(sx.Cons(in, nil))
			pos++
		} else {
			// lastPair is the term part and we need to append the inline list just read
			lastPair.Head().LastPair().AppendBang(in)
		}
		if sz.IsBreakSym(in.Car()) {
			return res, true
		}
	}
}

// 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()
	inp.SkipSpace()
	descrl := cp.descrl
	lastPair, pos := lastPairPos(descrl)
	if descrl == nil || pos <= 0 {
		// No term given
		return nil, false
	}

	pn := cp.parseLinePara()
	if len(pn) == 0 {
		return nil, false
	}

	newDef := sx.MakeList(sz.SymBlock, pn.MakeList().Cons(sz.SymPara))
	if pos%2 == 1 {
		// Just a term, but no definitions
		lastPair.AppendBang(sx.MakeList(sz.SymBlock, newDef))
	} else {
		// lastPara points a the last definition
		lastPair.Head().LastPair().AppendBang(newDef)
	}
	return nil, true
}

func lastPairPos(p *sx.Pair) (*sx.Pair, int) {
	cnt := 0
	for node := p; node != nil; {
		next := node.Tail()
		if next == nil {
			return node, cnt
		}
		node = next
		cnt++
	}
	return nil, -1
}

// parseIndent parses initial spaces to continue a list.
func (cp *zmkP) parseIndent() bool {
	inp := cp.inp
	cnt := 0
	for {
		if inp.Next() != ' ' {
			break
		}
		cnt++
	}
	if cp.lists != nil {
		return cp.parseIndentForList(cnt)
	}
	if cp.descrl != nil {
		return cp.parseIndentForDescription(cnt)
	}
	return false
}

func (cp *zmkP) parseIndentForList(cnt int) bool {
	if len(cp.lists) < cnt {
		cnt = len(cp.lists)
	}
	cp.lists = cp.lists[:cnt]
	if cnt == 0 {
		return false
	}
	pv := cp.parseLinePara()
	if len(pv) == 0 {
		return false
	}
	ln := cp.lists[cnt-1]
	lbn := ln.LastPair().Head()
	lpn := lbn.LastPair().Head()
	pvList := pv.MakeList()
	if lpn.Car().IsEqual(sz.SymPara) {
		lpn.LastPair().SetCdr(pvList)
	} else {
		lbn.LastPair().AppendBang(pvList.Cons(sz.SymPara))
	}
	return true
}

func (cp *zmkP) parseIndentForDescription(cnt int) bool {
	descrl := cp.descrl
	lastPair, pos := lastPairPos(descrl)
	if cnt < 1 || pos < 1 {
		return false
	}
	if pos%2 == 1 {
		// Continuation of a definition term
		for {
			in := cp.parseInline()
			if in == nil {
				return true
			}
			lastPair.Head().LastPair().AppendBang(in)
			if sz.IsBreakSym(in.Car()) {
				return true
			}
		}
	}

	// Continuation of a definition description
	pn := cp.parseLinePara()
	if len(pn) == 0 {
		return false
	}
	bn := lastPair.Head()
	para := bn.LastPair().Head().LastPair().Head()
	pnList := pn.MakeList()
	if para.Car().IsEqual(sz.SymPara) {
		para.LastPair().SetCdr(pnList)
	} else {
		bn.LastPair().AppendBang(pnList.Cons(sz.SymPara))
	}
	return true
}

// parseLinePara parses one paragraph of inline material.
func (cp *zmkP) parseLinePara() sx.Vector {
	var ins sx.Vector
	for {
		in := cp.parseInline()
		if in == nil {
			return ins
		}
		ins = append(ins, in)
		if sz.IsBreakSym(in.Car()) {
			return ins
		}
	}
}

// parseRow parse one table row.
func (cp *zmkP) parseRow() *sx.Pair {
	inp := cp.inp
	if inp.Peek() == '%' {
		inp.SkipToEOL()
		return nil
	}
	//var row, curr *sx.Pair
	var row sx.ListBuilder
	for {
		inp.Next()
		cell := cp.parseCell()
		if cell != nil {
			row.Add(cell)
		}
		switch inp.Ch {
		case '\n', '\r':
			inp.EatEOL()
			fallthrough
		case input.EOS:
			// add to table
			if cp.lastRow == nil {
				if row.IsEmpty() {
					return nil
				}
				cp.lastRow = sx.Cons(row.List(), nil)
				return cp.lastRow.Cons(nil).Cons(sz.SymTable)
			}
			cp.lastRow = cp.lastRow.AppendBang(row.List())
			return nil
		}
		// inp.Ch must be '|'
	}
}

// parseCell parses one single cell of a table row.
func (cp *zmkP) parseCell() *sx.Pair {
	inp := cp.inp
	var cell sx.ListBuilder
	for {
		if input.IsEOLEOS(inp.Ch) {
			if cell.IsEmpty() {
				return nil
			}
			return cell.List().Cons(sz.SymCell)
		}
		if inp.Ch == '|' {
			return cell.List().Cons(sz.SymCell)
		}

		in := cp.parseInline()
		cell.Add(in)
	}
}

// parseTransclusion parses '{' '{' '{' ZID '}' '}' '}'
func (cp *zmkP) parseTransclusion() (*sx.Pair, bool) {
	if cp.countDelim('{') != 3 {
		return nil, false
	}
	inp := cp.inp
	posA, posE := inp.Pos, 0

loop:

	for {
		switch inp.Ch {
		case input.EOS:
			return nil, false
		case '\n', '\r', ' ', '\t':
			if !hasQueryPrefix(inp.Src[posA:]) {
				return nil, false
			}
		case '\\':
			switch inp.Next() {
			case input.EOS, '\n', '\r':
				return nil, false
			}
		case '}':
			posE = inp.Pos
			if posA >= posE {
				return nil, false
			}
			if inp.Next() != '}' {
				continue
			}
			if inp.Next() != '}' {
				continue
			}
			break loop
		}
		inp.Next()
	}
	inp.Next() // consume last '}'
	a := cp.parseBlockAttributes()
	inp.SkipToEOL()
	refText := string(inp.Src[posA:posE])
	ref := ParseReference(refText)
	return sx.MakeList(sz.SymTransclude, a, ref), 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 zmk

import (
	"fmt"
	"strings"

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

func (cp *zmkP) parseInline() *sx.Pair {
	inp := cp.inp
	pos := inp.Pos
	if cp.nestingLevel <= maxNestingLevel {
		cp.nestingLevel++
		defer func() { cp.nestingLevel-- }()

		var in *sx.Pair
		success := false
		switch inp.Ch {
		case input.EOS:
			return nil
		case '\n', '\r':
			return cp.parseSoftBreak()
		case '[':
			switch inp.Next() {
			case '[':
				in, success = cp.parseLinkEmbed('[', ']', true)
			case '@':
				in, success = cp.parseCite()
			case '^':
				in, success = cp.parseEndnote()
			case '!':
				in, success = cp.parseMark()
			}
		case '{':
			if inp.Next() == '{' {
				in, success = cp.parseLinkEmbed('{', '}', false)
			}
		case '%':
			in, success = cp.parseComment()
		case '_', '*', '>', '~', '^', ',', '"', '#', ':':
			in, success = cp.parseFormat()
		case '@', '\'', '`', '=', runeModGrave:
			in, success = cp.parseLiteral()
		case '$':
			in, success = cp.parseLiteralMath()
		case '\\':
			return cp.parseBackslash()
		case '-':
			in, success = cp.parseNdash()
		case '&':
			in, success = cp.parseEntity()
		}
		if success {
			return in
		}
	}
	inp.SetPos(pos)
	return cp.parseText()
}

func (cp *zmkP) parseText() *sx.Pair {
	return sx.MakeList(sz.SymText, cp.parseString())
}

func (cp *zmkP) parseString() sx.String {
	inp := cp.inp
	pos := inp.Pos
	if inp.Ch == '\\' {
		cp.inp.Next()
		return cp.parseBackslashRest()
	}
	for {
		switch inp.Next() {
		// The following case must contain all runes that occur in parseInline!
		// Plus the closing brackets ] and } and ) and the middle |
		case input.EOS, '\n', '\r', '[', ']', '{', '}', '(', ')', '|', '%', '_', '*', '>', '~', '^', ',', '"', '#', ':', '\'', '@', '`', runeModGrave, '$', '=', '\\', '-', '&':
			return sx.MakeString(string(inp.Src[pos:inp.Pos]))
		}
	}
}

func (cp *zmkP) parseBackslash() *sx.Pair {
	inp := cp.inp
	switch inp.Next() {
	case '\n', '\r':
		inp.EatEOL()
		return sx.MakeList(sz.SymHard)
	default:
		return sx.MakeList(sz.SymText, cp.parseBackslashRest())
	}
}

func (cp *zmkP) parseBackslashRest() sx.String {
	inp := cp.inp
	if input.IsEOLEOS(inp.Ch) {
		return sx.MakeString("\\")
	}
	if inp.Ch == ' ' {
		inp.Next()
		return sx.MakeString("\u00a0")
	}
	pos := inp.Pos
	inp.Next()
	return sx.MakeString(string(inp.Src[pos:inp.Pos]))
}

func (cp *zmkP) parseSoftBreak() *sx.Pair {
	cp.inp.EatEOL()
	return sx.MakeList(sz.SymSoft)
}

func (cp *zmkP) parseLinkEmbed(openCh, closeCh rune, forLink bool) (*sx.Pair, bool) {
	if refString, text, ok := cp.parseReference(openCh, closeCh); ok {
		attrs := cp.parseInlineAttributes()
		if len(refString) > 0 {
			ref := ParseReference(refString)
			refSym, _ := sx.GetSymbol(ref.Car())
			sym := sz.MapRefStateToLinkEmbed(refSym, forLink)
			ln := text.
				Cons(ref.Tail().Car()). // reference value
				Cons(attrs).
				Cons(sym)
			return ln, true
		}
	}
	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()
	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:]) {
		hasSpace, ok := cp.readReferenceToSep(closeCh)
		if !ok {
			return "", nil, false
		}
		if inp.Ch == '|' { // First part must be inline text
			if pos == inp.Pos { // [[| or {{|
				return "", nil, false
			}
			cp.inp = input.NewInput(inp.Src[pos:inp.Pos])
			for {
				in := cp.parseInline()
				if in == nil {
					break
				}
				is = append(is, in)
			}
			cp.inp = inp
			inp.Next()
		} else {
			if hasSpace {
				return "", nil, false
			}
			inp.SetPos(pos)
		}
	}

	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
	}
	inp.Next()
	if len(is) == 0 {
		return ref, nil, true
	}
	return ref, sx.MakeList(is...), true
}

func (cp *zmkP) readReferenceToSep(closeCh rune) (bool, bool) {
	hasSpace := false
	inp := cp.inp
	for {
		switch inp.Ch {
		case input.EOS:
			return false, false
		case '\n', '\r', ' ':
			hasSpace = true
		case '|':
			return hasSpace, true
		case '\\':
			switch inp.Next() {
			case input.EOS:
				return false, false
			case '\n', '\r':
				hasSpace = true
			}
		case '%':
			if inp.Next() == '%' {
				inp.SkipToEOL()
			}
			continue
		case closeCh:
			if inp.Next() == closeCh {
				return hasSpace, true
			}
			continue
		}
		inp.Next()
	}
}

func (cp *zmkP) readReferenceToClose(closeCh rune) bool {
	inp := cp.inp
	pos := inp.Pos
	for {
		switch inp.Ch {
		case input.EOS:
			return false
		case '\t', '\r', '\n', ' ':
			if !hasQueryPrefix(inp.Src[pos:]) {
				return false
			}
		case '\\':
			switch inp.Next() {
			case input.EOS, '\n', '\r':
				return false
			}
		case closeCh:
			return true
		}
		inp.Next()
	}
}

func (cp *zmkP) parseCite() (*sx.Pair, bool) {
	inp := cp.inp
	switch inp.Next() {
	case ' ', ',', '|', ']', '\n', '\r':
		return nil, false
	}
	pos := inp.Pos
loop:
	for {
		switch inp.Ch {
		case input.EOS:
			return nil, false
		case ' ', ',', '|', ']', '\n', '\r':
			break loop
		}
		inp.Next()
	}
	posL := inp.Pos
	switch inp.Ch {
	case ' ', ',', '|':
		inp.Next()
	}
	ins, ok := cp.parseLinkLikeRest()
	if !ok {
		return nil, false
	}
	attrs := cp.parseInlineAttributes()
	cn := ins.Cons(sx.MakeString(string(inp.Src[pos:posL]))).Cons(attrs).Cons(sz.SymCite)
	return cn, true
}

func (cp *zmkP) parseEndnote() (*sx.Pair, bool) {
	cp.inp.Next()
	ins, ok := cp.parseLinkLikeRest()
	if !ok {
		return nil, false
	}
	attrs := cp.parseInlineAttributes()
	return ins.Cons(attrs).Cons(sz.SymEndnote), true
}

func (cp *zmkP) parseMark() (*sx.Pair, bool) {
	inp := cp.inp
	inp.Next()
	pos := inp.Pos
	for inp.Ch != '|' && inp.Ch != ']' {
		if !isNameRune(inp.Ch) {
			return nil, false
		}
		inp.Next()
	}
	mark := inp.Src[pos:inp.Pos]
	var ins *sx.Pair
	if inp.Ch == '|' {
		inp.Next()
		var ok bool
		ins, ok = cp.parseLinkLikeRest()
		if !ok {
			return nil, false
		}
	} else {
		inp.Next()
	}
	mn := ins.
		Cons(sx.MakeString("")). // Fragment
		Cons(sx.MakeString("")). // Slug
		Cons(sx.MakeString(string(mark))).
		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) {
	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()) {
			return nil, false
		}
	}
	inp.Next()
	if len(ins) == 0 {
		return nil, true
	}
	return sx.MakeList(ins...), true
}

func (cp *zmkP) parseComment() (res *sx.Pair, success bool) {
	inp := cp.inp
	if inp.Next() != '%' {
		return nil, false
	}
	for inp.Ch == '%' {
		inp.Next()
	}
	attrs := cp.parseInlineAttributes()
	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])),
			), true
		}
		inp.Next()
	}
}

var mapRuneFormat = map[rune]*sx.Symbol{
	'_': sz.SymFormatEmph,
	'*': sz.SymFormatStrong,
	'>': sz.SymFormatInsert,
	'~': sz.SymFormatDelete,
	'^': sz.SymFormatSuper,
	',': sz.SymFormatSub,
	'"': sz.SymFormatQuote,
	'#': sz.SymFormatMark,
	':': sz.SymFormatSpan,
}

func (cp *zmkP) parseFormat() (res *sx.Pair, success bool) {
	inp := cp.inp
	fch := inp.Ch
	symFormat, ok := mapRuneFormat[fch]
	if !ok {
		panic(fmt.Sprintf("%q is not a formatting char", fch))
	}
	// read 2nd formatting character
	if inp.Next() != fch {
		return nil, false
	}
	inp.Next()
	var inlines sx.Vector
	for {
		if inp.Ch == input.EOS {
			return nil, false
		}
		if inp.Ch == fch {
			if inp.Next() == fch {
				inp.Next()
				attrs := cp.parseInlineAttributes()
				fn := sx.MakeList(inlines...).Cons(attrs).Cons(symFormat)
				return fn, true
			}
			inlines = append(inlines, sx.MakeList(sz.SymText, sx.MakeString(string(fch))))
		} else if in := cp.parseInline(); in != nil {
			if input.IsEOLEOS(inp.Ch) && sz.IsBreakSym(in.Car()) {
				return nil, false
			}
			inlines = append(inlines, in)
		}
	}
}

var mapRuneLiteral = map[rune]*sx.Symbol{
	'@':          sz.SymLiteralZettel,
	'`':          sz.SymLiteralProg,
	runeModGrave: sz.SymLiteralProg,
	'\'':         sz.SymLiteralInput,
	'=':          sz.SymLiteralOutput,
	// No '$': sz.SymLiteralMath, because pairing literal math is a little different
}

func (cp *zmkP) parseLiteral() (res *sx.Pair, success bool) {
	inp := cp.inp
	fch := inp.Ch
	symLiteral, ok := mapRuneLiteral[fch]
	if !ok {
		panic(fmt.Sprintf("%q is not a formatting char", fch))
	}
	// read 2nd formatting character
	if inp.Next() != fch {
		return nil, false
	}
	inp.Next()
	var sb strings.Builder
	for {
		if inp.Ch == input.EOS {
			return nil, false
		}
		if inp.Ch == fch {
			if inp.Peek() == fch {
				inp.Next()
				inp.Next()
				return createLiteralNode(symLiteral, cp.parseInlineAttributes(), sb.String()), true
			}
			sb.WriteRune(fch)
			inp.Next()
		} else {
			s := cp.parseString()
			sb.WriteString(s.GetValue())
		}
	}
}

func createLiteralNode(sym *sx.Symbol, attrs *sx.Pair, content string) *sx.Pair {
	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(""))
			}
		}
	}
	return sx.MakeList(sym, attrs, sx.MakeString(content))
}

func (cp *zmkP) parseLiteralMath() (res *sx.Pair, success bool) {
	inp := cp.inp
	// read 2nd formatting character
	if inp.Next() != '$' {
		return nil, false
	}
	inp.Next()
	pos := inp.Pos
	for {
		if inp.Ch == input.EOS {
			return nil, false
		}
		if inp.Ch == '$' && inp.Peek() == '$' {
			content := append([]byte{}, inp.Src[pos:inp.Pos]...)
			inp.Next()
			inp.Next()
			fn := sx.MakeList(sz.SymLiteralMath, cp.parseInlineAttributes(), sx.MakeString(string(content)))
			return fn, true
		}
		inp.Next()
	}
}

func (cp *zmkP) parseNdash() (res *sx.Pair, success bool) {
	inp := cp.inp
	if inp.Peek() != inp.Ch {
		return nil, false
	}
	inp.Next()
	inp.Next()
	return sx.MakeList(sz.SymText, sx.MakeString("\u2013")), true
}

func (cp *zmkP) parseEntity() (res *sx.Pair, success bool) {
	if text, ok := cp.inp.ScanEntity(); ok {
		return sx.MakeList(sz.SymText, sx.MakeString(text)), true
	}
	return nil, false
}

//-----------------------------------------------------------------------------
// 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 (
	"strings"

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

var symInVerse = sx.MakeSymbol("in-verse")
var symNoBlock = sx.MakeSymbol("no-block")

type postProcessor struct{}

func (pp *postProcessor) Visit(lst *sx.Pair, env *sx.Pair) sx.Object {
	if lst == nil {
		return nil
	}
	sym, isSym := sx.GetSymbol(lst.Car())
	if !isSym {
		panic(lst)
	}
	if fn, found := symMap[sym]; found {
		return fn(pp, lst, env)
	}
	return sx.Int64(0)
}

func (pp *postProcessor) visitPairList(lst *sx.Pair, env *sx.Pair) *sx.Pair {
	var pList sx.ListBuilder
	for node := lst; node != nil; node = node.Tail() {
		if elem := sz.Walk(pp, node.Head(), env); elem != nil {
			pList.Add(elem)
		}
	}
	return pList.List()
}

var symMap map[*sx.Symbol]func(*postProcessor, *sx.Pair, *sx.Pair) *sx.Pair

func init() {
	symMap = map[*sx.Symbol]func(*postProcessor, *sx.Pair, *sx.Pair) *sx.Pair{
		sz.SymBlock:           postProcessBlockList,
		sz.SymPara:            postProcessInlineList,
		sz.SymRegionBlock:     postProcessRegion,
		sz.SymRegionQuote:     postProcessRegion,
		sz.SymRegionVerse:     postProcessRegionVerse,
		sz.SymVerbatimComment: postProcessVerbatim,
		sz.SymVerbatimEval:    postProcessVerbatim,
		sz.SymVerbatimMath:    postProcessVerbatim,
		sz.SymVerbatimProg:    postProcessVerbatim,
		sz.SymVerbatimZettel:  postProcessVerbatim,
		sz.SymHeading:         postProcessHeading,
		sz.SymListOrdered:     postProcessItemList,
		sz.SymListUnordered:   postProcessItemList,
		sz.SymListQuote:       postProcessQuoteList,
		sz.SymDescription:     postProcessDescription,
		sz.SymTable:           postProcessTable,

		sz.SymInline:       postProcessInlineList,
		sz.SymText:         postProcessText,
		sz.SymSoft:         postProcessSoft,
		sz.SymEndnote:      postProcessEndnote,
		sz.SymMark:         postProcessMark,
		sz.SymLinkBased:    postProcessInlines4,
		sz.SymLinkBroken:   postProcessInlines4,
		sz.SymLinkExternal: postProcessInlines4,
		sz.SymLinkFound:    postProcessInlines4,
		sz.SymLinkHosted:   postProcessInlines4,
		sz.SymLinkInvalid:  postProcessInlines4,
		sz.SymLinkQuery:    postProcessInlines4,
		sz.SymLinkSelf:     postProcessInlines4,
		sz.SymLinkZettel:   postProcessInlines4,
		sz.SymEmbed:        postProcessInlines4,
		sz.SymCite:         postProcessInlines4,
		sz.SymFormatDelete: postProcessFormat,
		sz.SymFormatEmph:   postProcessFormat,
		sz.SymFormatInsert: postProcessFormat,
		sz.SymFormatMark:   postProcessFormat,
		sz.SymFormatQuote:  postProcessFormat,
		sz.SymFormatStrong: postProcessFormat,
		sz.SymFormatSpan:   postProcessFormat,
		sz.SymFormatSub:    postProcessFormat,
		sz.SymFormatSuper:  postProcessFormat,

		symSeparator: ignoreProcess,
	}
}

func ignoreProcess(*postProcessor, *sx.Pair, *sx.Pair) *sx.Pair { return nil }

func postProcessBlockList(pp *postProcessor, lst *sx.Pair, env *sx.Pair) *sx.Pair {
	result := pp.visitPairList(lst.Tail(), env)
	if result == nil {
		if noBlockPair := env.Assoc(symNoBlock); noBlockPair == nil || sx.IsTrue(noBlockPair.Cdr()) {
			return nil
		}
	}
	return result.Cons(lst.Car())
}

func postProcessInlineList(pp *postProcessor, lst *sx.Pair, env *sx.Pair) *sx.Pair {
	sym := lst.Car()
	if rest := pp.visitInlines(lst.Tail(), env); rest != nil {
		return rest.Cons(sym)
	}
	return nil
}

func postProcessRegion(pp *postProcessor, rn *sx.Pair, env *sx.Pair) *sx.Pair {
	return doPostProcessRegion(pp, rn, env, env)
}

func postProcessRegionVerse(pp *postProcessor, rn *sx.Pair, env *sx.Pair) *sx.Pair {
	return doPostProcessRegion(pp, rn, env.Cons(sx.Cons(symInVerse, nil)), env)
}

func doPostProcessRegion(pp *postProcessor, rn *sx.Pair, envBlock, envInline *sx.Pair) *sx.Pair {

	sym := rn.Car()
	next := rn.Tail()
	attrs := next.Car()
	next = next.Tail()
	blocks := pp.visitPairList(next.Head(), envBlock)
	text := pp.visitInlines(next.Tail(), envInline)
	if blocks == nil && text == nil {
		return nil
	}
	return text.Cons(blocks).Cons(attrs).Cons(sym)
}

func postProcessVerbatim(_ *postProcessor, verb *sx.Pair, _ *sx.Pair) *sx.Pair {
	if content, isString := sx.GetString(verb.Tail().Tail().Car()); isString && content.GetValue() != "" {
		return verb
	}
	return nil
}

func postProcessHeading(pp *postProcessor, hn *sx.Pair, env *sx.Pair) *sx.Pair {
	sym := hn.Car()
	next := hn.Tail()
	level := next.Car()
	next = next.Tail()
	attrs := next.Car()
	next = next.Tail()
	slug := next.Car()
	next = next.Tail()
	fragment := next.Car()
	if text := pp.visitInlines(next.Tail(), env); text != nil {
		return text.Cons(fragment).Cons(slug).Cons(attrs).Cons(level).Cons(sym)
	}
	return nil
}

func postProcessItemList(pp *postProcessor, ln *sx.Pair, env *sx.Pair) *sx.Pair {
	elems := pp.visitListElems(ln, env)
	if elems == nil {
		return nil
	}
	return elems.Cons(ln.Car())
}

func postProcessQuoteList(pp *postProcessor, ln *sx.Pair, env *sx.Pair) *sx.Pair {
	elems := pp.visitListElems(ln, env.Cons(sx.Cons(symNoBlock, nil)))

	// Collect multiple paragraph items into one item.

	var newElems sx.ListBuilder
	var newPara sx.ListBuilder

	addtoParagraph := func() {
		if !newPara.IsEmpty() {
			newElems.Add(sx.MakeList(sz.SymBlock, newPara.List().Cons(sz.SymPara)))
		}
	}
	for node := elems; node != nil; node = node.Tail() {
		item := node.Head()
		if !item.Car().IsEqual(sz.SymBlock) {
			continue
		}
		itemTail := item.Tail()
		if itemTail == nil || itemTail.Tail() != nil {
			addtoParagraph()
			newElems.Add(item)
			continue
		}
		if pn := itemTail.Head(); pn.Car().IsEqual(sz.SymPara) {
			if !newPara.IsEmpty() {
				newPara.Add(sx.Cons(sz.SymSoft, nil))
			}
			newPara.ExtendBang(pn.Tail())
			continue
		}
		addtoParagraph()
		newElems.Add(item)
	}
	addtoParagraph()
	return newElems.List().Cons(ln.Car())
}

func (pp *postProcessor) visitListElems(ln *sx.Pair, env *sx.Pair) *sx.Pair {
	var pList sx.ListBuilder
	for node := ln.Tail(); node != nil; node = node.Tail() {
		if elem := sz.Walk(pp, node.Head(), env); elem != nil {
			pList.Add(elem)
		}
	}
	return pList.List()
}

func postProcessDescription(pp *postProcessor, dl *sx.Pair, env *sx.Pair) *sx.Pair {
	var dList sx.ListBuilder
	isTerm := false
	for node := dl.Tail(); node != nil; node = node.Tail() {
		isTerm = !isTerm
		if isTerm {
			dList.Add(pp.visitInlines(node.Head(), env))
		} else {
			dList.Add(sz.Walk(pp, node.Head(), env))
		}
	}
	return dList.List().Cons(dl.Car())
}

func postProcessTable(pp *postProcessor, tbl *sx.Pair, env *sx.Pair) *sx.Pair {
	sym := tbl.Car()
	next := tbl.Tail()
	header := next.Head()
	if header != nil {
		// Already post-processed
		return tbl
	}
	rows, width := pp.visitRows(next.Tail(), env)
	if rows == nil {
		// Header and row are nil -> no table
		return nil
	}
	header, rows, align := splitTableHeader(rows, width)
	alignRow(header, align)
	for node := rows; node != nil; node = node.Tail() {
		alignRow(node.Head(), align)
	}
	return rows.Cons(header).Cons(sym)
}

func (pp *postProcessor) visitRows(rows *sx.Pair, env *sx.Pair) (*sx.Pair, int) {
	maxWidth := 0
	var pRows sx.ListBuilder
	for node := rows; node != nil; node = node.Tail() {
		row := node.Head()
		row, width := pp.visitCells(row, env)
		if maxWidth < width {
			maxWidth = width
		}
		pRows.Add(row)
	}
	return pRows.List(), maxWidth
}

func (pp *postProcessor) visitCells(cells *sx.Pair, env *sx.Pair) (*sx.Pair, int) {
	width := 0
	var pCells sx.ListBuilder
	for node := cells; node != nil; node = node.Tail() {
		cell := node.Head()
		ins := pp.visitInlines(cell.Tail(), env)
		newCell := ins.Cons(cell.Car())
		pCells.Add(newCell)
		width++
	}
	return pCells.List(), width
}

func splitTableHeader(rows *sx.Pair, width int) (header, realRows *sx.Pair, align []*sx.Symbol) {
	align = make([]*sx.Symbol, width)

	foundHeader := false
	cellCount := 0

	// assert: rows != nil (checked in postProcessTable)
	for node := rows.Head(); node != nil; node = node.Tail() {
		cellCount++
		cell := node.Head()
		cellTail := cell.Tail()
		if cellTail == nil {
			continue
		}

		// 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()
				if str[0] == '=' {
					foundHeader = true
					elem.SetCdr(sx.Cons(sx.MakeString(str[1:]), nil))
				}
			}
		}

		// move to the last cell inline element
		for {
			next := cellTail.Tail()
			if next == nil {
				break
			}
			cellTail = next
		}

		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.IsEqualSymbol(sz.SymCell) {
					elem.SetCdr(sx.Cons(sx.MakeString(str[0:len(str)-1]), nil))
				}
				align[cellCount-1] = cellAlign
				cell.SetCar(cellAlign)
			}
		}
	}

	if !foundHeader {
		for i := 0; i < width; i++ {
			align[i] = sz.SymCell // Default alignment
		}
		return nil, rows, align
	}

	for i := 0; i < width; i++ {
		if align[i] == nil {
			align[i] = sz.SymCell // Default alignment
		}
	}
	return rows.Head(), rows.Tail(), align
}

func alignRow(row *sx.Pair, align []*sx.Symbol) {
	if row == nil {
		return
	}
	var lastCellNode *sx.Pair
	cellCount := 0
	for node := row; node != nil; node = node.Tail() {
		lastCellNode = node
		cell := node.Head()
		cell.SetCar(align[cellCount])
		cellCount++
		cellTail := cell.Tail()
		if cellTail == nil {
			continue
		}

		// 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.IsEqualSymbol(sz.SymCell) {
					elem.SetCdr(sx.Cons(sx.MakeString(str[1:]), nil))
					cell.SetCar(cellAlign)
				}
			}
		}
	}

	for cellCount < len(align) {
		lastCellNode = lastCellNode.AppendBang(sx.Cons(align[cellCount], nil))
		cellCount++
	}
}

func getCellAlignment(ch byte) *sx.Symbol {
	switch ch {
	case ':':
		return sz.SymCellCenter
	case '<':
		return sz.SymCellLeft
	case '>':
		return sz.SymCellRight
	default:
		return sz.SymCell
	}
}

func (pp *postProcessor) visitInlines(lst *sx.Pair, env *sx.Pair) *sx.Pair {
	length := lst.Length()
	if length <= 0 {
		return nil
	}
	inVerse := env.Assoc(symInVerse) != nil
	vector := make([]*sx.Pair, 0, length)
	// 1st phase: process all childs, ignore ' ' / '\t' at start, and merge some elements
	for node := lst; node != nil; node = node.Tail() {
		elem := sz.Walk(pp, node.Head(), env)
		if elem == nil {
			continue
		}
		elemSym := elem.Car()
		if len(vector) == 0 {
			// If the 1st element is a TEXT, remove all ' ', '\t' at the beginning, if outside a verse block.
			if inVerse || !elemSym.IsEqual(sz.SymText) {
				vector = append(vector, elem)
				continue
			}

			elemTail := elem.Tail()
			elemText := elemTail.Car().(sx.String).GetValue()
			if elemText != "" && (elemText[0] == ' ' || elemText[0] == '\t') {
				for elemText != "" {
					if ch := elemText[0]; ch != ' ' && ch != '\t' {
						break
					}
					elemText = elemText[1:]
				}
				elemTail.SetCar(sx.MakeString(elemText))
			}
			if elemText != "" {
				vector = append(vector, elem)
			}
			continue
		}
		last := vector[len(vector)-1]
		lastSym := last.Car()

		if lastSym.IsEqual(sz.SymText) && elemSym.IsEqual(sz.SymText) {
			// Merge two TEXT elements into one
			lastText := last.Tail().Car().(sx.String).GetValue()
			elemText := elem.Tail().Car().(sx.String).GetValue()
			last.SetCdr(sx.Cons(sx.MakeString(lastText+elemText), sx.Nil()))
			continue
		}

		if lastSym.IsEqual(sz.SymText) && elemSym.IsEqual(sz.SymSoft) {
			// Merge (TEXT "... ") (SOFT) to (TEXT "...") (HARD)
			lastTail := last.Tail()
			if lastText := lastTail.Car().(sx.String).GetValue(); strings.HasSuffix(lastText, " ") {
				newText := removeTrailingSpaces(lastText)
				if newText == "" {
					vector[len(vector)-1] = sx.Cons(sz.SymHard, sx.Nil())
					continue
				}
				lastTail.SetCar(sx.MakeString(newText))
				elemSym = sz.SymHard
				elem.SetCar(elemSym)
			}
		}

		vector = append(vector, elem)
	}
	if len(vector) == 0 {
		return nil
	}

	// 2nd phase: remove (SOFT), (HARD) at the end, remove trailing spaces in (TEXT "...")
	lastPos := len(vector) - 1
	for lastPos >= 0 {
		elem := vector[lastPos]
		elemSym := elem.Car()
		if elemSym.IsEqual(sz.SymText) {
			elemTail := elem.Tail()
			elemText := elemTail.Car().(sx.String).GetValue()
			newText := removeTrailingSpaces(elemText)
			if newText != "" {
				elemTail.SetCar(sx.MakeString(newText))
				break
			}
			lastPos--
		} else if sz.IsBreakSym(elemSym) {
			lastPos--
		} else {
			break
		}
	}
	if lastPos < 0 {
		return nil
	}

	result := sx.Cons(vector[0], nil)
	curr := result
	for i := 1; i <= lastPos; i++ {
		curr = curr.AppendBang(vector[i])
	}
	return result
}

func removeTrailingSpaces(s string) string {
	for len(s) > 0 {
		if ch := s[len(s)-1]; ch != ' ' && ch != '\t' {
			return s
		}
		s = s[0 : len(s)-1]
	}
	return ""
}

func postProcessText(_ *postProcessor, txt *sx.Pair, _ *sx.Pair) *sx.Pair {
	if tail := txt.Tail(); tail != nil {
		if content, isString := sx.GetString(tail.Car()); isString && content.GetValue() != "" {
			return txt
		}
	}
	return nil
}

func postProcessSoft(_ *postProcessor, sn *sx.Pair, env *sx.Pair) *sx.Pair {
	if env.Assoc(symInVerse) == nil {
		return sn
	}
	return sx.Cons(sz.SymHard, nil)
}

func postProcessEndnote(pp *postProcessor, en *sx.Pair, env *sx.Pair) *sx.Pair {
	sym := en.Car()
	next := en.Tail()
	attrs := next.Car()
	if text := pp.visitInlines(next.Tail(), env); text != nil {
		return text.Cons(attrs).Cons(sym)
	}
	return sx.MakeList(sym, attrs)
}

func postProcessMark(pp *postProcessor, en *sx.Pair, env *sx.Pair) *sx.Pair {
	sym := en.Car()
	next := en.Tail()
	mark := next.Car()
	next = next.Tail()
	slug := next.Car()
	next = next.Tail()
	fragment := next.Car()
	text := pp.visitInlines(next.Tail(), env)
	return text.Cons(fragment).Cons(slug).Cons(mark).Cons(sym)
}

func postProcessInlines4(pp *postProcessor, ln *sx.Pair, env *sx.Pair) *sx.Pair {
	sym := ln.Car()
	next := ln.Tail()
	attrs := next.Car()
	next = next.Tail()
	val3 := next.Car()
	text := pp.visitInlines(next.Tail(), env)
	return text.Cons(val3).Cons(attrs).Cons(sym)
}

func postProcessFormat(pp *postProcessor, fn *sx.Pair, env *sx.Pair) *sx.Pair {
	symFormat := fn.Car()
	next := fn.Tail() // Attrs
	attrs := next.Car()
	next = next.Tail() // Possible inlines
	if next == nil {
		return fn
	}
	inlines := pp.visitInlines(next, env)
	return inlines.Cons(attrs).Cons(symFormat)
}

// -----------------------------------------------------------------------------
// 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.IsEqualSymbol(sz.SymRefStateBased) {
			s = s[1:]
		}
		_, err := url.Parse(s)
		if err == nil {
			return makePairRef(state, s)
		}
	}
	u, err := url.Parse(s)
	if err != nil {
		return makePairRef(sz.SymRefStateInvalid, s)
	}
	if !externalURL(u) {
		zid := api.ZettelID(u.Path)
		if zid.IsValid() {
			return makePairRef(sz.SymRefStateZettel, s)
		}
		if u.Path == "" && u.Fragment != "" {
			return makePairRef(sz.SymRefStateSelf, s)
		}
	}
	return makePairRef(sz.SymRefStateExternal, s)
}
func makePairRef(sym *sx.Symbol, val string) *sx.Pair {
	return sx.MakeList(sym, sx.MakeString(val))
}

func invalidReference(s string) bool { return s == "" || s == "00000000000000" }

func externalURL(u *url.URL) bool {
	return u.Scheme != "" || u.Opaque != "" || u.Host != "" || u.User != nil
}

func localState(path string) (*sx.Symbol, bool) {
	if len(path) > 0 && path[0] == '/' {
		if len(path) > 1 && path[1] == '/' {
			return sz.SymRefStateBased, true
		}
		return sz.SymRefStateHosted, true
	}
	if len(path) > 1 && path[0] == '.' {
		if len(path) > 2 && path[1] == '.' && path[2] == '/' {
			return sz.SymRefStateHosted, true
		}
		return sz.SymRefStateHosted, path[1] == '/'
	}
	return sz.SymRefStateInvalid, false
}

// ReferenceIsValid returns true if reference is valid
func ReferenceIsValid(ref *sx.Pair) bool {
	return !ref.Car().IsEqual(sz.SymRefStateInvalid)
}

// ReferenceIsZettel returns true if it is a reference to a local zettel.
func ReferenceIsZettel(ref *sx.Pair) bool {
	state := ref.Car()
	return state.IsEqual(sz.SymRefStateZettel) ||
		state.IsEqual(sz.SymRefStateSelf) ||
		state.IsEqual(sz.SymRefStateFound) ||
		state.IsEqual(sz.SymRefStateBroken)
}

// ReferenceIsLocal returns true if reference is local
func ReferenceIsLocal(ref *sx.Pair) bool {
	state := ref.Car()
	return state.IsEqual(sz.SymRefStateHosted) ||
		state.IsEqual(sz.SymRefStateBased)
}

// ReferenceIsExternal returns true if it is a reference to external material.
func ReferenceIsExternal(ref *sx.Pair) bool {
	return ref.Car().IsEqual(sz.SymRefStateExternal)
}