Add clickable Markdown checkboxes (#182)

internal/render/markdown.go

@@ -1,15 +1,24 @@
 package render
 
 import (
+	"bufio"
 	"bytes"
+	"github.com/Kunde21/markdownfmt/v3"
 	"github.com/alecthomas/chroma/v2/formatters/html"
+	"github.com/rs/zerolog/log"
 	"github.com/thomiceli/opengist/internal/db"
 	"github.com/thomiceli/opengist/internal/git"
 	"github.com/yuin/goldmark"
 	emoji "github.com/yuin/goldmark-emoji"
 	highlighting "github.com/yuin/goldmark-highlighting/v2"
+	"github.com/yuin/goldmark/ast"
 	"github.com/yuin/goldmark/extension"
+	astex "github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
 	"go.abhg.dev/goldmark/mermaid"
+	"strconv"
 )
 
 func MarkdownGistPreview(gist *db.Gist) (RenderedGist, error) {
@@ -43,5 +52,62 @@ func newMarkdown() goldmark.Markdown {
 			emoji.Emoji,
 			&mermaid.Extender{},
 		),
+		goldmark.WithParserOptions(
+			parser.WithASTTransformers(
+				util.Prioritized(&CheckboxTransformer{}, 10000),
+			),
+		),
 	)
 }
+
+type CheckboxTransformer struct{}
+
+func (t *CheckboxTransformer) Transform(node *ast.Document, _ text.Reader, _ parser.Context) {
+	i := 1
+	err := ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
+		if entering {
+			if _, ok := n.(*astex.TaskCheckBox); ok {
+				listitem := n.Parent().Parent()
+				listitem.SetAttribute([]byte("data-checkbox-nb"), []byte(strconv.Itoa(i)))
+				i += 1
+			}
+		}
+		return ast.WalkContinue, nil
+	})
+	if err != nil {
+		log.Err(err)
+	}
+}
+
+func Checkbox(content string, checkboxNb int) (string, error) {
+	buf := bytes.Buffer{}
+	w := bufio.NewWriter(&buf)
+
+	source := []byte(content)
+	markdown := markdownfmt.NewGoldmark()
+	reader := text.NewReader(source)
+	document := markdown.Parser().Parse(reader)
+
+	i := 1
+	err := ast.Walk(document, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
+		if entering {
+			if listItem, ok := n.(*astex.TaskCheckBox); ok {
+				if i == checkboxNb {
+					listItem.IsChecked = !listItem.IsChecked
+				}
+				i += 1
+			}
+		}
+		return ast.WalkContinue, nil
+	})
+	if err != nil {
+		return "", err
+	}
+
+	if err = markdown.Renderer().Render(w, source, document); err != nil {
+		return "", err
+	}
+	_ = w.Flush()
+
+	return buf.String(), nil
+}