bin/*
releases/*
parser/pikchr/*.out

Copyright (c) 2020-present Detlef Stern
Copyright (c) 2020-2023 Detlef Stern

                          Licensed under the EUPL

Zettelstore is licensed under the European Union Public License, version 1.2 or
later (EUPL v. 1.2). The license is available in the official languages of the
EU. The English version is included here. Please see
https://joinup.ec.europa.eu/community/eupl/og_page/eupl for official

## Copyright (c) 2020-present Detlef Stern
## Copyright (c) 2020-2022 Detlef Stern
##
## This file is part of Zettelstore.
##
## Zettelstore is licensed under the latest version of the EUPL (European Union
## Public License). Please see file LICENSE.txt for your rights and obligations
## under this license.

.PHONY:  check relcheck api version build release clean
.PHONY:  check relcheck api build release clean

check:
	go run tools/check/check.go
	go run tools/build.go check

relcheck:
	go run tools/check/check.go -r
	go run tools/build.go relcheck

api:
	go run tools/testapi/testapi.go
	go run tools/build.go testapi

version:
	@echo $(shell go run tools/build/build.go version)
	@echo $(shell go run tools/build.go version)

build:
	go run tools/build/build.go build
	go run tools/build.go build

release:
	go run tools/build/build.go release
	go run tools/build.go release

clean:
	go run tools/clean/clean.go
	go run tools/build.go clean

gradually, one major focus is a long-term store of these notes, hence the name
“Zettelstore”.

To get an initial impression, take a look at the
[manual](https://zettelstore.de/manual/). It is a live example of the
zettelstore software, running in read-only mode.

[Zettelstore Client](https://t73f.de/r/zsc) provides client software to access
Zettelstore via its API more easily, [Zettelstore
[Zettelstore Client](https://zettelstore.de/client) provides client
software to access Zettelstore via its API more easily, [Zettelstore
Contrib](https://zettelstore.de/contrib) contains contributed software, which
often connects to Zettelstore via its API. Some of the software packages may be
experimental.

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

[Stay](https://twitter.com/zettelstore)
[Stay tuned](https://mastodon.social/tags/Zettelstore) …
<a rel="me" href="https://nerdculture.de/@zettelstore">tuned</a>&nbsp;&hellip;

0.21.0-dev
0.10.1

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

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

import (
	"net/url"

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

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

// Node is the interface, all nodes must implement.
type Node interface {
	WalkChildren(v Visitor)
}

// BlockNode is the interface that all block nodes must implement.
type BlockNode interface {
	Node
	blockNode()
}

// ItemNode is a node that can occur as a list item.
type ItemNode interface {
	BlockNode
	itemNode()
}

// ItemSlice is a slice of ItemNodes.
type ItemSlice []ItemNode

// DescriptionNode is a node that contains just textual description.
type DescriptionNode interface {
	ItemNode
	descriptionNode()
}

// DescriptionSlice is a slice of DescriptionNodes.
type DescriptionSlice []DescriptionNode

// InlineNode is the interface that all inline nodes must implement.
type InlineNode interface {
	Node
	inlineNode()
}

// Reference is a reference to external or internal material.
type Reference struct {
	URL   *url.URL
	Value string
	State RefState
}

// RefState indicates the state of the reference.
type RefState int

// Constants for RefState
const (
	RefStateInvalid  RefState = iota // Invalid Reference
	RefStateZettel                   // Reference to an internal zettel
	RefStateSelf                     // Reference to same zettel with a fragment
	RefStateFound                    // Reference to an existing internal zettel, URL is ajusted
	RefStateBroken                   // Reference to a non-existing internal zettel
	RefStateHosted                   // Reference to local hosted non-Zettel, without URL change
	RefStateBased                    // Reference to local non-Zettel, to be prefixed
	RefStateQuery                    // Reference to a zettel query
	RefStateExternal                 // Reference to external material
)

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2023 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package ast

import "zettelstore.de/c/attrs"

// Definition of Block nodes.

// BlockSlice is a slice of BlockNodes.
type BlockSlice []BlockNode

func (*BlockSlice) blockNode() { /* Just a marker */ }

// WalkChildren walks down to the descriptions.
func (bs *BlockSlice) WalkChildren(v Visitor) {
	if bs != nil {
		for _, bn := range *bs {
			Walk(v, bn)
		}
	}
}

// FirstParagraphInlines returns the inline list of the first paragraph that
// contains a inline list.
func (bs BlockSlice) FirstParagraphInlines() InlineSlice {
	for _, bn := range bs {
		pn, ok := bn.(*ParaNode)
		if !ok {
			continue
		}
		if inl := pn.Inlines; len(inl) > 0 {
			return inl
		}
	}
	return nil
}

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

// ParaNode contains just a sequence of inline elements.
// Another name is "paragraph".
type ParaNode struct {
	Inlines InlineSlice
}

func (*ParaNode) blockNode()       { /* Just a marker */ }
func (*ParaNode) itemNode()        { /* Just a marker */ }
func (*ParaNode) descriptionNode() { /* Just a marker */ }

// CreateParaNode creates a parameter block from inline nodes.
func CreateParaNode(nodes ...InlineNode) *ParaNode { return &ParaNode{Inlines: nodes} }

// WalkChildren walks down the inline elements.
func (pn *ParaNode) WalkChildren(v Visitor) { Walk(v, &pn.Inlines) }

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

// VerbatimNode contains uninterpreted text
type VerbatimNode struct {
	Kind    VerbatimKind
	Attrs   attrs.Attributes
	Content []byte
}

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

// Constants for VerbatimCode
const (
	_               VerbatimKind = iota
	VerbatimZettel               // Zettel content
	VerbatimProg                 // Program code
	VerbatimEval                 // Code to be externally interpreted. Syntax is stored in default attribute.
	VerbatimComment              // Block comment
	VerbatimHTML                 // Block HTML, e.g. for Markdown
	VerbatimMath                 // Block math mode
)

func (*VerbatimNode) blockNode() { /* Just a marker */ }
func (*VerbatimNode) itemNode()  { /* Just a marker */ }

// WalkChildren does nothing.
func (*VerbatimNode) WalkChildren(Visitor) { /* No children*/ }

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

// RegionNode encapsulates a region of block nodes.
type RegionNode struct {
	Kind    RegionKind
	Attrs   attrs.Attributes
	Blocks  BlockSlice
	Inlines InlineSlice // Optional text at the end of the region
}

// RegionKind specifies the actual region type.
type RegionKind int

// Values for RegionCode
const (
	_           RegionKind = iota
	RegionSpan             // Just a span of blocks
	RegionQuote            // A longer quotation
	RegionVerse            // Line breaks matter
)

func (*RegionNode) blockNode() { /* Just a marker */ }
func (*RegionNode) itemNode()  { /* Just a marker */ }

// WalkChildren walks down the blocks and the text.
func (rn *RegionNode) WalkChildren(v Visitor) {
	Walk(v, &rn.Blocks)
	Walk(v, &rn.Inlines)
}

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

// HeadingNode stores the heading text and level.
type HeadingNode struct {
	Level    int
	Attrs    attrs.Attributes
	Slug     string      // Heading text, normalized
	Fragment string      // Heading text, suitable to be used as an unique URL fragment
	Inlines  InlineSlice // Heading text, possibly formatted
}

func (*HeadingNode) blockNode() { /* Just a marker */ }
func (*HeadingNode) itemNode()  { /* Just a marker */ }

// WalkChildren walks the heading text.
func (hn *HeadingNode) WalkChildren(v Visitor) { Walk(v, &hn.Inlines) }

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

// HRuleNode specifies a horizontal rule.
type HRuleNode struct {
	Attrs attrs.Attributes
}

func (*HRuleNode) blockNode() { /* Just a marker */ }
func (*HRuleNode) itemNode()  { /* Just a marker */ }

// WalkChildren does nothing.
func (*HRuleNode) WalkChildren(Visitor) { /* No children*/ }

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

// NestedListNode specifies a nestable list, either ordered or unordered.
type NestedListNode struct {
	Kind  NestedListKind
	Items []ItemSlice
	Attrs attrs.Attributes
}

// NestedListKind specifies the actual list type.
type NestedListKind uint8

// Values for ListCode
const (
	_                   NestedListKind = iota
	NestedListOrdered                  // Ordered list.
	NestedListUnordered                // Unordered list.
	NestedListQuote                    // Quote list.
)

func (*NestedListNode) blockNode() { /* Just a marker */ }
func (*NestedListNode) itemNode()  { /* Just a marker */ }

// WalkChildren walks down the items.
func (ln *NestedListNode) WalkChildren(v Visitor) {
	if items := ln.Items; items != nil {
		for _, item := range items {
			WalkItemSlice(v, item)
		}
	}
}

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

// DescriptionListNode specifies a description list.
type DescriptionListNode struct {
	Descriptions []Description
}

// Description is one element of a description list.
type Description struct {
	Term         InlineSlice
	Descriptions []DescriptionSlice
}

func (*DescriptionListNode) blockNode() { /* Just a marker */ }

// WalkChildren walks down to the descriptions.
func (dn *DescriptionListNode) WalkChildren(v Visitor) {
	if descrs := dn.Descriptions; descrs != nil {
		for i, desc := range descrs {
			if len(desc.Term) > 0 {
				Walk(v, &descrs[i].Term) // Otherwise, changes in desc.Term will not go back into AST
			}
			if dss := desc.Descriptions; dss != nil {
				for _, dns := range dss {
					WalkDescriptionSlice(v, dns)
				}
			}
		}
	}
}

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

// TableNode specifies a full table
type TableNode struct {
	Header TableRow    // The header row
	Align  []Alignment // Default column alignment
	Rows   []TableRow  // The slice of cell rows
}

// TableCell contains the data for one table cell
type TableCell struct {
	Align   Alignment   // Cell alignment
	Inlines InlineSlice // Cell content
}

// TableRow is a slice of cells.
type TableRow []*TableCell

// Alignment specifies text alignment.
// Currently only for tables.
type Alignment int

// Constants for Alignment.
const (
	_            Alignment = iota
	AlignDefault           // Default alignment, inherited
	AlignLeft              // Left alignment
	AlignCenter            // Center the content
	AlignRight             // Right alignment
)

func (*TableNode) blockNode() { /* Just a marker */ }

// WalkChildren walks down to the cells.
func (tn *TableNode) WalkChildren(v Visitor) {
	if header := tn.Header; header != nil {
		for i := range header {
			Walk(v, &header[i].Inlines) // Otherwise changes will not go back
		}
	}
	if rows := tn.Rows; rows != nil {
		for _, row := range rows {
			for i := range row {
				Walk(v, &row[i].Inlines) // Otherwise changes will not go back
			}
		}
	}
}

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

// TranscludeNode specifies block content from other zettel to embedded in
// current zettel
type TranscludeNode struct {
	Attrs attrs.Attributes
	Ref   *Reference
}

func (*TranscludeNode) blockNode() { /* Just a marker */ }

// WalkChildren does nothing.
func (*TranscludeNode) WalkChildren(Visitor) { /* No children*/ }

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

// BLOBNode contains just binary data that must be interpreted according to
// a syntax.
type BLOBNode struct {
	Description InlineSlice
	Syntax      string
	Blob        []byte
}

func (*BLOBNode) blockNode() { /* Just a marker */ }

// WalkChildren does nothing.
func (*BLOBNode) WalkChildren(Visitor) { /* No children*/ }

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package ast

import (
	"unicode/utf8"

	"zettelstore.de/c/attrs"
)

// Definitions of inline nodes.

// InlineSlice is a list of BlockNodes.
type InlineSlice []InlineNode

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

// CreateInlineSliceFromWords makes a new inline list from words,
// that will be space-separated.
func CreateInlineSliceFromWords(words ...string) InlineSlice {
	inl := make(InlineSlice, 0, 2*len(words)-1)
	for i, word := range words {
		if i > 0 {
			inl = append(inl, &SpaceNode{Lexeme: " "})
		}
		inl = append(inl, &TextNode{Text: word})
	}
	return inl
}

// WalkChildren walks down to the list.
func (is *InlineSlice) WalkChildren(v Visitor) {
	for _, in := range *is {
		Walk(v, in)
	}
}

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

// TextNode just contains some text.
type TextNode struct {
	Text string // The text itself.
}

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

// WalkChildren does nothing.
func (*TextNode) WalkChildren(Visitor) { /* No children*/ }

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

// SpaceNode tracks inter-word space characters.
type SpaceNode struct {
	Lexeme string
}

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

// WalkChildren does nothing.
func (*SpaceNode) WalkChildren(Visitor) { /* No children*/ }

// Count returns the number of space runes.
func (sn *SpaceNode) Count() int {
	return utf8.RuneCountInString(sn.Lexeme)
}

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

// BreakNode signals a new line that must / should be interpreted as a new line break.
type BreakNode struct {
	Hard bool // Hard line break?
}

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

// WalkChildren does nothing.
func (*BreakNode) WalkChildren(Visitor) { /* No children*/ }

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

// LinkNode contains the specified link.
type LinkNode struct {
	Attrs   attrs.Attributes // Optional attributes
	Ref     *Reference
	Inlines InlineSlice // The text associated with the link.
}

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

// WalkChildren walks to the link text.
func (ln *LinkNode) WalkChildren(v Visitor) {
	if len(ln.Inlines) > 0 {
		Walk(v, &ln.Inlines)
	}
}

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

// EmbedRefNode contains the specified embedded reference material.
type EmbedRefNode struct {
	Attrs   attrs.Attributes // Optional attributes
	Ref     *Reference       // The reference to be embedded.
	Syntax  string           // Syntax of referenced material, if known
	Inlines InlineSlice      // Optional text associated with the image.
}

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

// WalkChildren walks to the text that describes the embedded material.
func (en *EmbedRefNode) WalkChildren(v Visitor) { Walk(v, &en.Inlines) }

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

// EmbedBLOBNode contains the specified embedded BLOB material.
type EmbedBLOBNode struct {
	Attrs   attrs.Attributes // Optional attributes
	Syntax  string           // Syntax of Blob
	Blob    []byte           // BLOB data itself.
	Inlines InlineSlice      // Optional text associated with the image.
}

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

// WalkChildren walks to the text that describes the embedded material.
func (en *EmbedBLOBNode) WalkChildren(v Visitor) { Walk(v, &en.Inlines) }

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

// CiteNode contains the specified citation.
type CiteNode struct {
	Attrs   attrs.Attributes // Optional attributes
	Key     string           // The citation key
	Inlines InlineSlice      // Optional text associated with the citation.
}

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

// WalkChildren walks to the cite text.
func (cn *CiteNode) WalkChildren(v Visitor) { Walk(v, &cn.Inlines) }

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

// MarkNode contains the specified merked position.
// It is a BlockNode too, because although it is typically parsed during inline
// mode, it is moved into block mode afterwards.
type MarkNode struct {
	Mark     string      // The mark text itself
	Slug     string      // Slugified form of Mark
	Fragment string      // Unique form of Slug
	Inlines  InlineSlice // Marked inline content
}

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

// WalkChildren does nothing.
func (mn *MarkNode) WalkChildren(v Visitor) {
	if len(mn.Inlines) > 0 {
		Walk(v, &mn.Inlines)
	}
}

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

// FootnoteNode contains the specified footnote.
type FootnoteNode struct {
	Attrs   attrs.Attributes // Optional attributes
	Inlines InlineSlice      // The footnote text.
}

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

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

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

// FormatNode specifies some inline formatting.
type FormatNode struct {
	Kind    FormatKind
	Attrs   attrs.Attributes // Optional attributes.
	Inlines InlineSlice
}

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

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

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

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

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

// LiteralNode specifies some uninterpreted text.
type LiteralNode struct {
	Kind    LiteralKind
	Attrs   attrs.Attributes // Optional attributes.
	Content []byte
}

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

// Constants for LiteralCode
const (
	_              LiteralKind = iota
	LiteralZettel              // Zettel content
	LiteralProg                // Inline program code
	LiteralInput               // Computer input, e.g. Keyboard strokes
	LiteralOutput              // Computer output
	LiteralComment             // Inline comment
	LiteralHTML                // Inline HTML, e.g. for Markdown
	LiteralMath                // Inline math mode
)

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

// WalkChildren does nothing.
func (*LiteralNode) WalkChildren(Visitor) { /* No children*/ }

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package ast

import (
	"net/url"
	"strings"

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

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

// ParseReference parses a string and returns a reference.
func ParseReference(s string) *Reference {
	if invalidReference(s) {
		return &Reference{URL: nil, Value: s, State: RefStateInvalid}
	}
	if strings.HasPrefix(s, QueryPrefix) {
		return &Reference{URL: nil, Value: s[len(QueryPrefix):], State: RefStateQuery}
	}
	if state, ok := localState(s); ok {
		if state == RefStateBased {
			s = s[1:]
		}
		u, err := url.Parse(s)
		if err == nil {
			return &Reference{URL: u, Value: s, State: state}
		}
	}
	u, err := url.Parse(s)
	if err != nil {
		return &Reference{URL: nil, Value: s, State: RefStateInvalid}
	}
	if !externalURL(u) {
		if _, err = id.Parse(u.Path); err == nil {
			return &Reference{URL: u, Value: s, State: RefStateZettel}
		}
		if u.Path == "" && u.Fragment != "" {
			return &Reference{URL: u, Value: s, State: RefStateSelf}
		}
	}
	return &Reference{URL: u, Value: s, State: RefStateExternal}
}

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) (RefState, bool) {
	if len(path) > 0 && path[0] == '/' {
		if len(path) > 1 && path[1] == '/' {
			return RefStateBased, true
		}
		return RefStateHosted, true
	}
	if len(path) > 1 && path[0] == '.' {
		if len(path) > 2 && path[1] == '.' && path[2] == '/' {
			return RefStateHosted, true
		}
		return RefStateHosted, path[1] == '/'
	}
	return RefStateInvalid, false
}

// String returns the string representation of a reference.
func (r Reference) String() string {
	if r.URL != nil {
		return r.URL.String()
	}
	if r.State == RefStateQuery {
		return QueryPrefix + r.Value
	}
	return r.Value
}

// IsValid returns true if reference is valid
func (r *Reference) IsValid() bool { return r.State != RefStateInvalid }

// IsZettel returns true if it is a referencen to a local zettel.
func (r *Reference) IsZettel() bool {
	switch r.State {
	case RefStateZettel, RefStateSelf, RefStateFound, RefStateBroken:
		return true
	}
	return false
}

// IsLocal returns true if reference is local
func (r *Reference) IsLocal() bool {
	return r.State == RefStateHosted || r.State == RefStateBased
}

// IsExternal returns true if it is a referencen to external material.
func (r *Reference) IsExternal() bool { return r.State == RefStateExternal }

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package ast_test

import (
	"testing"

	"zettelstore.de/z/ast"
)

func TestParseReference(t *testing.T) {
	t.Parallel()
	testcases := []struct {
		link string
		err  bool
		exp  string
	}{
		{"", true, ""},
		{"123", false, "123"},
		{",://", true, ""},
	}

	for i, tc := range testcases {
		got := ast.ParseReference(tc.link)
		if got.IsValid() == tc.err {
			t.Errorf(
				"TC=%d, expected parse error of %q: %v, but got %q", i, tc.link, tc.err, got)
		}
		if got.IsValid() && got.String() != tc.exp {
			t.Errorf("TC=%d, Reference of %q is %q, but got %q", i, tc.link, tc.exp, got)
		}
	}
}

func TestReferenceIsZettelMaterial(t *testing.T) {
	t.Parallel()
	testcases := []struct {
		link       string
		isZettel   bool
		isExternal bool
		isLocal    bool
	}{
		{"", false, false, false},
		{"00000000000000", false, false, false},
		{"http://zettelstore.de/z/ast", false, true, false},
		{"12345678901234", true, false, false},
		{"12345678901234#local", true, false, false},
		{"http://12345678901234", false, true, false},
		{"http://zettelstore.de/z/12345678901234", false, true, false},
		{"http://zettelstore.de/12345678901234", false, true, false},
		{"/12345678901234", false, false, true},
		{"//12345678901234", false, false, true},
		{"./12345678901234", false, false, true},
		{"../12345678901234", false, false, true},
		{".../12345678901234", false, true, false},
	}

	for i, tc := range testcases {
		ref := ast.ParseReference(tc.link)
		isZettel := ref.IsZettel()
		if isZettel != tc.isZettel {
			t.Errorf(
				"TC=%d, Reference %q isZettel=%v expected, but got %v",
				i,
				tc.link,
				tc.isZettel,
				isZettel)
		}
		isLocal := ref.IsLocal()
		if isLocal != tc.isLocal {
			t.Errorf(
				"TC=%d, Reference %q isLocal=%v expected, but got %v",
				i,
				tc.link,
				tc.isLocal, isLocal)
		}
		isExternal := ref.IsExternal()
		if isExternal != tc.isExternal {
			t.Errorf(
				"TC=%d, Reference %q isExternal=%v expected, but got %v",
				i,
				tc.link,
				tc.isExternal,
				isExternal)
		}
	}
}

//-----------------------------------------------------------------------------
// Copyright (c) 2021-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package ast

// Visitor is a visitor for walking the AST.
type Visitor interface {
	Visit(node Node) Visitor
}

// Walk traverses the AST.
func Walk(v Visitor, node Node) {
	if v = v.Visit(node); v == nil {
		return
	}

	// Implementation note:
	// It is much faster to use interface dispatching than to use a switch statement.
	// On my "cpu: Intel(R) Core(TM) i7-6820HQ CPU @ 2.70GHz", a switch statement
	// implementation tooks approx 940-980 ns/op. Interface dispatching is in the
	// range of 900-930 ns/op.
	node.WalkChildren(v)
	v.Visit(nil)
}

// WalkItemSlice traverses an item slice.
func WalkItemSlice(v Visitor, ins ItemSlice) {
	for _, in := range ins {
		Walk(v, in)
	}
}

// WalkDescriptionSlice traverses an item slice.
func WalkDescriptionSlice(v Visitor, dns DescriptionSlice) {
	for _, dn := range dns {
		Walk(v, dn)
	}
}

//-----------------------------------------------------------------------------
// Copyright (c) 2021-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package ast_test

import (
	"testing"

	"zettelstore.de/c/attrs"
	"zettelstore.de/z/ast"
)

func BenchmarkWalk(b *testing.B) {
	root := ast.BlockSlice{
		&ast.HeadingNode{
			Inlines: ast.CreateInlineSliceFromWords("A", "Simple", "Heading"),
		},
		&ast.ParaNode{
			Inlines: ast.CreateInlineSliceFromWords("This", "is", "the", "introduction."),
		},
		&ast.NestedListNode{
			Kind: ast.NestedListUnordered,
			Items: []ast.ItemSlice{
				[]ast.ItemNode{
					&ast.ParaNode{
						Inlines: ast.CreateInlineSliceFromWords("Item", "1"),
					},
				},
				[]ast.ItemNode{
					&ast.ParaNode{
						Inlines: ast.CreateInlineSliceFromWords("Item", "2"),
					},
				},
			},
		},
		&ast.ParaNode{
			Inlines: ast.CreateInlineSliceFromWords("This", "is", "some", "intermediate", "text."),
		},
		ast.CreateParaNode(
			&ast.FormatNode{
				Kind: ast.FormatEmph,
				Attrs: attrs.Attributes(map[string]string{
					"":      "class",
					"color": "green",
				}),
				Inlines: ast.CreateInlineSliceFromWords("This", "is", "some", "emphasized", "text."),
			},
			&ast.SpaceNode{Lexeme: " "},
			&ast.LinkNode{
				Ref:     &ast.Reference{Value: "http://zettelstore.de"},
				Inlines: ast.CreateInlineSliceFromWords("URL", "text."),
			},
		),
	}
	v := benchVisitor{}
	b.ResetTimer()
	for n := 0; n < b.N; n++ {
		ast.Walk(&v, &root)
	}
}

type benchVisitor struct{}

func (bv *benchVisitor) Visit(ast.Node) ast.Visitor { return bv }

//-----------------------------------------------------------------------------
// Copyright (c) 2021-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

// Package auth provides services for authentification / authorization.
package auth

import (
	"time"

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

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

// TokenManager provides methods to create authentication
type TokenManager interface {

	// GetToken produces a authentication token.
	GetToken(ident *meta.Meta, d time.Duration, kind TokenKind) ([]byte, error)

	// CheckToken checks the validity of the token and returns relevant data.
	CheckToken(token []byte, k TokenKind) (TokenData, error)
}

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

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

// TokenData contains some important elements from a token.
type TokenData struct {
	Token   []byte
	Now     time.Time
	Issued  time.Time
	Expires time.Time
	Ident   string
	Zid     id.Zid
}

// AuthzManager provides methods for authorization.
type AuthzManager interface {
	BaseManager

	// Owner returns the zettel identifier of the owner.
	Owner() id.Zid

	// IsOwner returns true, if the given zettel identifier is that of the owner.
	IsOwner(zid id.Zid) bool

	// Returns true if authentication is enabled.
	WithAuth() bool

	// GetUserRole role returns the user role of the given user zettel.
	GetUserRole(user *meta.Meta) meta.UserRole
}

// Manager is the main interface for providing the service.
type Manager interface {
	TokenManager
	AuthzManager

	BoxWithPolicy(unprotectedBox box.Box, rtConfig config.Config) (box.Box, Policy)
}

// Policy is an interface for checking access authorization.
type Policy interface {
	// User is allowed to create a new zettel.
	CanCreate(user, newMeta *meta.Meta) bool

	// User is allowed to read zettel
	CanRead(user, m *meta.Meta) bool

	// User is allowed to write zettel.
	CanWrite(user, oldMeta, newMeta *meta.Meta) bool

	// User is allowed to rename zettel
	CanRename(user, m *meta.Meta) bool

	// User is allowed to delete zettel.
	CanDelete(user, m *meta.Meta) bool

	// User is allowed to refresh box data.
	CanRefresh(user *meta.Meta) bool
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

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

import (
	"bytes"

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

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

// CompareHashAndCredential checks, whether the hashed credential is a possible
// value when hashing the credential.
func CompareHashAndCredential(hashed string, zid id.Zid, ident, credential string) (bool, error) {
	fullCredential := createFullCredential(zid, ident, credential)
	err := bcrypt.CompareHashAndPassword([]byte(hashed), fullCredential)
	if err == nil {
		return true, nil
	}
	if err == bcrypt.ErrMismatchedHashAndPassword {
		return false, nil
	}
	return false, err
}

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

//-----------------------------------------------------------------------------
// Copyright (c) 2021-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

// Package impl provides services for authentification / authorization.
package impl

import (
	"errors"
	"hash/fnv"
	"io"
	"time"

	"github.com/pascaldekloe/jwt"

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

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

// New creates a new auth object.
func New(readonly bool, owner id.Zid, extSecret string) auth.Manager {
	return &myAuth{
		readonly: readonly,
		owner:    owner,
		secret:   calcSecret(extSecret),
	}
}

var configKeys = []string{
	kernel.CoreProgname,
	kernel.CoreGoVersion,
	kernel.CoreHostname,
	kernel.CoreGoOS,
	kernel.CoreGoArch,
	kernel.CoreVersion,
}

func calcSecret(extSecret string) []byte {
	h := fnv.New128()
	if extSecret != "" {
		io.WriteString(h, extSecret)
	}
	for _, key := range configKeys {
		io.WriteString(h, kernel.Main.GetConfig(kernel.CoreService, key).(string))
	}
	return h.Sum(nil)
}

// IsReadonly returns true, if the systems is configured to run in read-only-mode.
func (a *myAuth) IsReadonly() bool { return a.readonly }

const reqHash = jwt.HS512

// ErrNoIdent signals that the 'ident' key is missing.
var ErrNoIdent = errors.New("auth: missing ident")

// ErrOtherKind signals that the token was defined for another token kind.
var ErrOtherKind = errors.New("auth: wrong token kind")

// ErrNoZid signals that the 'zid' key is missing.
var ErrNoZid = errors.New("auth: missing zettel id")

// GetToken returns a token to be used for authentification.
func (a *myAuth) GetToken(ident *meta.Meta, d time.Duration, kind auth.TokenKind) ([]byte, error) {
	subject, ok := ident.Get(api.KeyUserID)
	if !ok || subject == "" {
		return nil, ErrNoIdent
	}

	now := time.Now().Round(time.Second)
	claims := jwt.Claims{
		Registered: jwt.Registered{
			Subject: subject,
			Expires: jwt.NewNumericTime(now.Add(d)),
			Issued:  jwt.NewNumericTime(now),
		},
		Set: map[string]interface{}{
			"zid": ident.Zid.String(),
			"_tk": int(kind),
		},
	}
	token, err := claims.HMACSign(reqHash, a.secret)
	if err != nil {
		return nil, err
	}
	return token, nil
}

// ErrTokenExpired signals an exired token
var ErrTokenExpired = errors.New("auth: token expired")

// CheckToken checks the validity of the token and returns relevant data.
func (a *myAuth) CheckToken(token []byte, k auth.TokenKind) (auth.TokenData, error) {
	h, err := jwt.NewHMAC(reqHash, a.secret)
	if err != nil {
		return auth.TokenData{}, err
	}
	claims, err := h.Check(token)
	if err != nil {
		return auth.TokenData{}, err
	}
	now := time.Now().Round(time.Second)
	expires := claims.Expires.Time()
	if expires.Before(now) {
		return auth.TokenData{}, ErrTokenExpired
	}
	ident := claims.Subject
	if ident == "" {
		return auth.TokenData{}, ErrNoIdent
	}
	if zidS, ok := claims.Set["zid"].(string); ok {
		if zid, err2 := id.Parse(zidS); err2 == nil {
			if kind, ok2 := claims.Set["_tk"].(float64); ok2 {
				if auth.TokenKind(kind) == k {
					return auth.TokenData{
						Token:   token,
						Now:     now,
						Issued:  claims.Issued.Time(),
						Expires: expires,
						Ident:   ident,
						Zid:     zid,
					}, nil
				}
			}
			return auth.TokenData{}, ErrOtherKind
		}
	}
	return auth.TokenData{}, ErrNoZid
}

func (a *myAuth) Owner() id.Zid { return a.owner }

func (a *myAuth) IsOwner(zid id.Zid) bool {
	return zid.IsValid() && zid == a.owner
}

func (a *myAuth) WithAuth() bool { return a.owner != id.Invalid }

// GetUserRole role returns the user role of the given user zettel.
func (a *myAuth) GetUserRole(user *meta.Meta) meta.UserRole {
	if user == nil {
		if a.WithAuth() {
			return meta.UserRoleUnknown
		}
		return meta.UserRoleOwner
	}
	if a.IsOwner(user.Zid) {
		return meta.UserRoleOwner
	}
	if val, ok := user.Get(api.KeyUserRole); ok {
		if ur := meta.GetUserRole(val); ur != meta.UserRoleUnknown {
			return ur
		}
	}
	return meta.UserRoleReader
}

func (a *myAuth) BoxWithPolicy(unprotectedBox box.Box, rtConfig config.Config) (box.Box, auth.Policy) {
	return policy.BoxWithPolicy(a, unprotectedBox, rtConfig)
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package policy

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

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

func (ap *anonPolicy) CanCreate(user, newMeta *meta.Meta) bool {
	return ap.pre.CanCreate(user, newMeta)
}

func (ap *anonPolicy) CanRead(user, m *meta.Meta) bool {
	return ap.pre.CanRead(user, m) && ap.checkVisibility(m)
}

func (ap *anonPolicy) CanWrite(user, oldMeta, newMeta *meta.Meta) bool {
	return ap.pre.CanWrite(user, oldMeta, newMeta) && ap.checkVisibility(oldMeta)
}

func (ap *anonPolicy) CanRename(user, m *meta.Meta) bool {
	return ap.pre.CanRename(user, m) && ap.checkVisibility(m)
}

func (ap *anonPolicy) CanDelete(user, m *meta.Meta) bool {
	return ap.pre.CanDelete(user, m) && ap.checkVisibility(m)
}

func (ap *anonPolicy) CanRefresh(user *meta.Meta) bool {
	if ap.authConfig.GetExpertMode() || ap.authConfig.GetSimpleMode() {
		return true
	}
	return ap.pre.CanRefresh(user)
}

func (ap *anonPolicy) checkVisibility(m *meta.Meta) bool {
	if ap.authConfig.GetVisibility(m) == meta.VisibilityExpert {
		return ap.authConfig.GetExpertMode()
	}
	return true
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package policy

import (
	"context"

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

// BoxWithPolicy wraps the given box inside a policy box.
func BoxWithPolicy(
	manager auth.AuthzManager,
	box box.Box,
	authConfig config.AuthConfig,
) (box.Box, auth.Policy) {
	pol := newPolicy(manager, authConfig)
	return newBox(box, pol), pol
}

// polBox implements a policy box.
type polBox struct {
	box    box.Box
	policy auth.Policy
}

// newBox creates a new policy box.
func newBox(box box.Box, policy auth.Policy) box.Box {
	return &polBox{
		box:    box,
		policy: policy,
	}
}

func (pp *polBox) Location() string {
	return pp.box.Location()
}

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

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

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

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

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

func (pp *polBox) GetAllMeta(ctx context.Context, zid id.Zid) ([]*meta.Meta, error) {
	return pp.box.GetAllMeta(ctx, zid)
}

func (pp *polBox) FetchZids(ctx context.Context) (id.Set, error) {
	return nil, box.NewErrNotAllowed("fetch-zids", server.GetUser(ctx), id.Invalid)
}

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

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

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

func (pp *polBox) AllowRenameZettel(ctx context.Context, zid id.Zid) bool {
	return pp.box.AllowRenameZettel(ctx, zid)
}

func (pp *polBox) RenameZettel(ctx context.Context, curZid, newZid id.Zid) error {
	meta, err := pp.box.GetMeta(ctx, curZid)
	if err != nil {
		return err
	}
	user := server.GetUser(ctx)
	if pp.policy.CanRename(user, meta) {
		return pp.box.RenameZettel(ctx, curZid, newZid)
	}
	return box.NewErrNotAllowed("Rename", user, curZid)
}

func (pp *polBox) CanDeleteZettel(ctx context.Context, zid id.Zid) bool {
	return pp.box.CanDeleteZettel(ctx, zid)
}

func (pp *polBox) DeleteZettel(ctx context.Context, zid id.Zid) error {
	meta, err := pp.box.GetMeta(ctx, zid)
	if err != nil {
		return err
	}
	user := server.GetUser(ctx)
	if pp.policy.CanDelete(user, meta) {
		return pp.box.DeleteZettel(ctx, zid)
	}
	return box.NewErrNotAllowed("Delete", user, zid)
}

func (pp *polBox) Refresh(ctx context.Context) error {
	user := server.GetUser(ctx)
	if pp.policy.CanRefresh(user) {
		return pp.box.Refresh(ctx)
	}
	return box.NewErrNotAllowed("Refresh", user, id.Invalid)
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package policy

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

type defaultPolicy struct {
	manager auth.AuthzManager
}

func (*defaultPolicy) CanCreate(_, _ *meta.Meta) bool { return true }
func (*defaultPolicy) CanRead(_, _ *meta.Meta) bool   { return true }
func (d *defaultPolicy) CanWrite(user, oldMeta, _ *meta.Meta) bool {
	return d.canChange(user, oldMeta)
}
func (d *defaultPolicy) CanRename(user, m *meta.Meta) bool { return d.canChange(user, m) }
func (d *defaultPolicy) CanDelete(user, m *meta.Meta) bool { return d.canChange(user, m) }

func (*defaultPolicy) CanRefresh(user *meta.Meta) bool { return user != nil }

func (d *defaultPolicy) canChange(user, m *meta.Meta) bool {
	metaRo, ok := m.Get(api.KeyReadOnly)
	if !ok {
		return true
	}
	if user == nil {
		// If we are here, there is no authentication.
		// See owner.go:CanWrite.

		// No authentication: check for owner-like restriction, because the user
		// acts as an owner
		return metaRo != api.ValueUserRoleOwner && !meta.BoolValue(metaRo)
	}

	userRole := d.manager.GetUserRole(user)
	switch metaRo {
	case api.ValueUserRoleReader:
		return userRole > meta.UserRoleReader
	case api.ValueUserRoleWriter:
		return userRole > meta.UserRoleWriter
	case api.ValueUserRoleOwner:
		return userRole > meta.UserRoleOwner
	}
	return !meta.BoolValue(metaRo)
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

package policy

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

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

func (o *ownerPolicy) CanCreate(user, newMeta *meta.Meta) bool {
	if user == nil || !o.pre.CanCreate(user, newMeta) {
		return false
	}
	return o.userIsOwner(user) || o.userCanCreate(user, newMeta)
}

func (o *ownerPolicy) userCanCreate(user, newMeta *meta.Meta) bool {
	if o.manager.GetUserRole(user) == meta.UserRoleReader {
		return false
	}
	if _, ok := newMeta.Get(api.KeyUserID); ok {
		return false
	}
	return true
}

func (o *ownerPolicy) CanRead(user, m *meta.Meta) bool {
	// No need to call o.pre.CanRead(user, meta), because it will always return true.
	// Both the default and the readonly policy allow to read a zettel.
	vis := o.authConfig.GetVisibility(m)
	if res, ok := o.checkVisibility(user, vis); ok {
		return res
	}
	return o.userIsOwner(user) || o.userCanRead(user, m, vis)
}

func (o *ownerPolicy) userCanRead(user, m *meta.Meta, vis meta.Visibility) bool {
	switch vis {
	case meta.VisibilityOwner, meta.VisibilityExpert:
		return false
	case meta.VisibilityPublic:
		return true
	}
	if user == nil {
		return false
	}
	if _, ok := m.Get(api.KeyUserID); ok {
		// Only the user can read its own zettel
		return user.Zid == m.Zid
	}
	switch o.manager.GetUserRole(user) {
	case meta.UserRoleReader, meta.UserRoleWriter, meta.UserRoleOwner:
		return true
	case meta.UserRoleCreator:
		return vis == meta.VisibilityCreator
	default:
		return false
	}
}

var noChangeUser = []string{
	api.KeyID,
	api.KeyRole,
	api.KeyUserID,
	api.KeyUserRole,
}

func (o *ownerPolicy) CanWrite(user, oldMeta, newMeta *meta.Meta) bool {
	if user == nil || !o.pre.CanWrite(user, oldMeta, newMeta) {
		return false
	}
	vis := o.authConfig.GetVisibility(oldMeta)
	if res, ok := o.checkVisibility(user, vis); ok {
		return res
	}
	if o.userIsOwner(user) {
		return true
	}
	if !o.userCanRead(user, oldMeta, vis) {
		return false
	}
	if _, ok := oldMeta.Get(api.KeyUserID); ok {
		// Here we know, that user.Zid == newMeta.Zid (because of userCanRead) and
		// user.Zid == newMeta.Zid (because oldMeta.Zid == newMeta.Zid)
		for _, key := range noChangeUser {
			if oldMeta.GetDefault(key, "") != newMeta.GetDefault(key, "") {
				return false
			}
		}
		return true
	}
	switch userRole := o.manager.GetUserRole(user); userRole {
	case meta.UserRoleReader, meta.UserRoleCreator:
		return false
	}
	return o.userCanCreate(user, newMeta)
}

func (o *ownerPolicy) CanRename(user, m *meta.Meta) bool {
	if user == nil || !o.pre.CanRename(user, m) {
		return false
	}
	if res, ok := o.checkVisibility(user, o.authConfig.GetVisibility(m)); ok {
		return res
	}
	return o.userIsOwner(user)
}

func (o *ownerPolicy) CanDelete(user, m *meta.Meta) bool {
	if user == nil || !o.pre.CanDelete(user, m) {
		return false
	}
	if res, ok := o.checkVisibility(user, o.authConfig.GetVisibility(m)); ok {
		return res
	}
	return o.userIsOwner(user)
}

func (o *ownerPolicy) CanRefresh(user *meta.Meta) bool {
	switch userRole := o.manager.GetUserRole(user); userRole {
	case meta.UserRoleUnknown:
		return o.authConfig.GetSimpleMode()
	case meta.UserRoleCreator:
		return o.authConfig.GetExpertMode() || o.authConfig.GetSimpleMode()
	}
	return true
}

func (o *ownerPolicy) checkVisibility(user *meta.Meta, vis meta.Visibility) (bool, bool) {
	if vis == meta.VisibilityExpert {
		return o.userIsOwner(user) && o.authConfig.GetExpertMode(), true
	}
	return false, false
}

func (o *ownerPolicy) userIsOwner(user *meta.Meta) bool {
	if user == nil {
		return false
	}
	if o.manager.IsOwner(user.Zid) {
		return true
	}
	if val, ok := user.Get(api.KeyUserRole); ok && val == api.ValueUserRoleOwner {
		return true
	}
	return false
}

//-----------------------------------------------------------------------------
// Copyright (c) 2020-2022 Detlef Stern
//
// This file is part of Zettelstore.
//
// Zettelstore is licensed under the latest version of the EUPL (European Union
// Public License). Please see file LICENSE.txt for your rights and obligations
// under this license.
//-----------------------------------------------------------------------------

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

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

// newPolicy creates a policy based on given constraints.
func newPolicy(manager auth.AuthzManager, authConfig config.AuthConfig) auth.Policy {
	var pol auth.Policy
	if manager.IsReadonly() {
		pol = &roPolicy{}
	} else {
		pol = &defaultPolicy{manager}
	}
	if manager.WithAuth() {
		pol = &ownerPolicy{
			manager:    manager,
			authConfig: authConfig,
			pre:        pol,
		}
	} else {
		pol = &anonPolicy{
			authConfig: authConfig,
			pre:        pol,
		}
	}
	return &prePolicy{pol}
}

type prePolicy struct {
	post auth.Policy
}

func (p *prePolicy) CanCreate(user, newMeta *meta.Meta) bool {
	return newMeta != nil && p.post.CanCreate(user, newMeta)
}

func (p *prePolicy) CanRead(user, m *meta.Meta) bool {
	return m != nil && p.post.CanRead(user, m)
}

func (p *prePolicy) CanWrite(user, oldMeta, newMeta *meta.Meta) bool {
	return oldMeta != nil && newMeta != nil && oldMeta.Zid == newMeta.Zid &&
		p.post.CanWrite(user, oldMeta, newMeta)
}

func (p *prePolicy) CanRename(user, m *meta.Meta) bool {
	return m != nil && p.post.CanRename(user, m)
}

func (p *prePolicy) CanDelete(user, m *meta.Meta) bool {
	return m != nil && p.post.CanDelete(user, m)
}

func (p *prePolicy) CanRefresh(user *meta.Meta) bool {
	return p.post.CanRefresh(user)
}