Use markdown frontmatter to provide Table of contents, language and f…

…rontmatter rendering (go-gitea#11047)

* Add control for the rendering of the frontmatter
* Add control to include a TOC
* Add control to set language - allows control of ToC header and CJK glyph choice.

Signed-off-by: Andrew Thornton art27@cantab.net

go.mod

@@ -124,6 +124,7 @@ require (
 	gopkg.in/ini.v1 v1.52.0
 	gopkg.in/ldap.v3 v3.0.2
 	gopkg.in/testfixtures.v2 v2.5.0
+	gopkg.in/yaml.v2 v2.2.8
 	mvdan.cc/xurls/v2 v2.1.0
 	strk.kbt.io/projects/go/libravatar v0.0.0-20191008002943-06d1c002b251
 	xorm.io/builder v0.3.7

modules/markup/html.go

@@ -351,6 +351,27 @@ func (ctx *postProcessCtx) visitNode(node *html.Node, visitText bool) {
 			visitText = false
 		} else if node.Data == "code" || node.Data == "pre" {
 			return
+		} else if node.Data == "i" {
+			for _, attr := range node.Attr {
+				if attr.Key != "class" {
+					continue
+				}
+				classes := strings.Split(attr.Val, " ")
+				for i, class := range classes {
+					if class == "icon" {
+						classes[0], classes[i] = classes[i], classes[0]
+						attr.Val = strings.Join(classes, " ")
+
+						// Remove all children of icons
+						child := node.FirstChild
+						for child != nil {
+							node.RemoveChild(child)
+							child = node.FirstChild
+						}
+						break
+					}
+				}
+			}
 		}
 		for n := node.FirstChild; n != nil; n = n.NextSibling {
 			ctx.visitNode(n, visitText)

modules/markup/markdown/ast.go

@@ -0,0 +1,107 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package markdown
+
+import "github.com/yuin/goldmark/ast"
+
+// Details is a block that contains Summary and details
+type Details struct {
+	ast.BaseBlock
+}
+
+// Dump implements Node.Dump .
+func (n *Details) Dump(source []byte, level int) {
+	ast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindDetails is the NodeKind for Details
+var KindDetails = ast.NewNodeKind("Details")
+
+// Kind implements Node.Kind.
+func (n *Details) Kind() ast.NodeKind {
+	return KindDetails
+}
+
+// NewDetails returns a new Paragraph node.
+func NewDetails() *Details {
+	return &Details{
+		BaseBlock: ast.BaseBlock{},
+	}
+}
+
+// IsDetails returns true if the given node implements the Details interface,
+// otherwise false.
+func IsDetails(node ast.Node) bool {
+	_, ok := node.(*Details)
+	return ok
+}
+
+// Summary is a block that contains the summary of details block
+type Summary struct {
+	ast.BaseBlock
+}
+
+// Dump implements Node.Dump .
+func (n *Summary) Dump(source []byte, level int) {
+	ast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindSummary is the NodeKind for Summary
+var KindSummary = ast.NewNodeKind("Summary")
+
+// Kind implements Node.Kind.
+func (n *Summary) Kind() ast.NodeKind {
+	return KindSummary
+}
+
+// NewSummary returns a new Summary node.
+func NewSummary() *Summary {
+	return &Summary{
+		BaseBlock: ast.BaseBlock{},
+	}
+}
+
+// IsSummary returns true if the given node implements the Summary interface,
+// otherwise false.
+func IsSummary(node ast.Node) bool {
+	_, ok := node.(*Summary)
+	return ok
+}
+
+// Icon is an inline for a fomantic icon
+type Icon struct {
+	ast.BaseInline
+	Name []byte
+}
+
+// Dump implements Node.Dump .
+func (n *Icon) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Name"] = string(n.Name)
+	ast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindIcon is the NodeKind for Icon
+var KindIcon = ast.NewNodeKind("Icon")
+
+// Kind implements Node.Kind.
+func (n *Icon) Kind() ast.NodeKind {
+	return KindIcon
+}
+
+// NewIcon returns a new Paragraph node.
+func NewIcon(name string) *Icon {
+	return &Icon{
+		BaseInline: ast.BaseInline{},
+		Name:       []byte(name),
+	}
+}
+
+// IsIcon returns true if the given node implements the Icon interface,
+// otherwise false.
+func IsIcon(node ast.Node) bool {
+	_, ok := node.(*Icon)
+	return ok
+}

modules/markup/markdown/goldmark.go

@@ -7,12 +7,16 @@ package markdown
 import (
 	"bytes"
 	"fmt"
+	"regexp"
 	"strings"
 
+	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/markup/common"
+	"code.gitea.io/gitea/modules/setting"
 	giteautil "code.gitea.io/gitea/modules/util"
 
+	meta "github.com/yuin/goldmark-meta"
 	"github.com/yuin/goldmark/ast"
 	east "github.com/yuin/goldmark/extension/ast"
 	"github.com/yuin/goldmark/parser"
@@ -24,17 +28,56 @@ import (
 
 var byteMailto = []byte("mailto:")
 
-// GiteaASTTransformer is a default transformer of the goldmark tree.
-type GiteaASTTransformer struct{}
+// Header holds the data about a header.
+type Header struct {
+	Level int
+	Text  string
+	ID    string
+}
+
+// ASTTransformer is a default transformer of the goldmark tree.
+type ASTTransformer struct{}
 
 // Transform transforms the given AST tree.
-func (g *GiteaASTTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) {
+func (g *ASTTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) {
+	metaData := meta.GetItems(pc)
+	firstChild := node.FirstChild()
+	createTOC := false
+	var toc = []Header{}
+	rc := &RenderConfig{
+		Meta: "table",
+		Icon: "table",
+		Lang: "",
+	}
+	if metaData != nil {
+		rc.ToRenderConfig(metaData)
+
+		metaNode := rc.toMetaNode(metaData)
+		if metaNode != nil {
+			node.InsertBefore(node, firstChild, metaNode)
+		}
+		createTOC = rc.TOC
+		toc = make([]Header, 0, 100)
+	}
+
 	_ = ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
 		if !entering {
 			return ast.WalkContinue, nil
 		}
 
 		switch v := n.(type) {
+		case *ast.Heading:
+			if createTOC {
+				text := n.Text(reader.Source())
+				header := Header{
+					Text:  util.BytesToReadOnlyString(text),
+					Level: v.Level,
+				}
+				if id, found := v.AttributeString("id"); found {
+					header.ID = util.BytesToReadOnlyString(id.([]byte))
+				}
+				toc = append(toc, header)
+			}
 		case *ast.Image:
 			// Images need two things:
 			//
@@ -91,6 +134,21 @@ func (g *GiteaASTTransformer) Transform(node *ast.Document, reader text.Reader,
 		}
 		return ast.WalkContinue, nil
 	})
+
+	if createTOC && len(toc) > 0 {
+		lang := rc.Lang
+		if len(lang) == 0 {
+			lang = setting.Langs[0]
+		}
+		tocNode := createTOCNode(toc, lang)
+		if tocNode != nil {
+			node.InsertBefore(node, firstChild, tocNode)
+		}
+	}
+
+	if len(rc.Lang) > 0 {
+		node.SetAttributeString("lang", []byte(rc.Lang))
+	}
 }
 
 type prefixedIDs struct {
@@ -139,10 +197,10 @@ func newPrefixedIDs() *prefixedIDs {
 	}
 }
 
-// NewTaskCheckBoxHTMLRenderer creates a TaskCheckBoxHTMLRenderer to render tasklists
+// NewHTMLRenderer creates a HTMLRenderer to render
 // in the gitea form.
-func NewTaskCheckBoxHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
-	r := &TaskCheckBoxHTMLRenderer{
+func NewHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
+	r := &HTMLRenderer{
 		Config: html.NewConfig(),
 	}
 	for _, opt := range opts {
@@ -151,19 +209,109 @@ func NewTaskCheckBoxHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
 	return r
 }
 
-// TaskCheckBoxHTMLRenderer is a renderer.NodeRenderer implementation that
-// renders checkboxes in list items.
-// Overrides the default goldmark one to present the gitea format
-type TaskCheckBoxHTMLRenderer struct {
+// HTMLRenderer is a renderer.NodeRenderer implementation that
+// renders gitea specific features.
+type HTMLRenderer struct {
 	html.Config
 }
 
 // RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
-func (r *TaskCheckBoxHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+func (r *HTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindDocument, r.renderDocument)
+	reg.Register(KindDetails, r.renderDetails)
+	reg.Register(KindSummary, r.renderSummary)
+	reg.Register(KindIcon, r.renderIcon)
 	reg.Register(east.KindTaskCheckBox, r.renderTaskCheckBox)
 }
 
-func (r *TaskCheckBoxHTMLRenderer) renderTaskCheckBox(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+func (r *HTMLRenderer) renderDocument(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	log.Info("renderDocument %v", node)
+	n := node.(*ast.Document)
+
+	if val, has := n.AttributeString("lang"); has {
+		var err error
+		if entering {
+			_, err = w.WriteString("<div")
+			if err == nil {
+				_, err = w.WriteString(fmt.Sprintf(` lang=%q`, val))
+			}
+			if err == nil {
+				_, err = w.WriteRune('>')
+			}
+		} else {
+			_, err = w.WriteString("</div>")
+		}
+
+		if err != nil {
+			return ast.WalkStop, err
+		}
+	}
+
+	return ast.WalkContinue, nil
+}
+
+func (r *HTMLRenderer) renderDetails(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	var err error
+	if entering {
+		_, err = w.WriteString("<details>")
+	} else {
+		_, err = w.WriteString("</details>")
+	}
+
+	if err != nil {
+		return ast.WalkStop, err
+	}
+
+	return ast.WalkContinue, nil
+}
+
+func (r *HTMLRenderer) renderSummary(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	var err error
+	if entering {
+		_, err = w.WriteString("<summary>")
+	} else {
+		_, err = w.WriteString("</summary>")
+	}
+
+	if err != nil {
+		return ast.WalkStop, err
+	}
+
+	return ast.WalkContinue, nil
+}
+
+var validNameRE = regexp.MustCompile("^[a-z ]+$")
+
+func (r *HTMLRenderer) renderIcon(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+
+	n := node.(*Icon)
+
+	name := strings.TrimSpace(strings.ToLower(string(n.Name)))
+
+	if len(name) == 0 {
+		// skip this
+		return ast.WalkContinue, nil
+	}
+
+	if !validNameRE.MatchString(name) {
+		// skip this
+		return ast.WalkContinue, nil
+	}
+
+	var err error
+	_, err = w.WriteString(fmt.Sprintf(`<i class="icon %s"></i>`, name))
+
+	if err != nil {
+		return ast.WalkStop, err
+	}
+
+	return ast.WalkContinue, nil
+}
+
+func (r *HTMLRenderer) renderTaskCheckBox(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
 	if !entering {
 		return ast.WalkContinue, nil
 	}