GoBlog/markdown.go

150 lines
4.1 KiB
Go

package main
import (
"bytes"
"strings"
kemoji "github.com/kyokomi/emoji/v2"
"github.com/yuin/goldmark"
emoji "github.com/yuin/goldmark-emoji"
"github.com/yuin/goldmark-emoji/definition"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/extension"
"github.com/yuin/goldmark/parser"
"github.com/yuin/goldmark/renderer"
"github.com/yuin/goldmark/renderer/html"
"github.com/yuin/goldmark/util"
)
var emojilib definition.Emojis
var defaultMarkdown, absoluteMarkdown goldmark.Markdown
func initMarkdown() {
defaultGoldmarkOptions := []goldmark.Option{
goldmark.WithRendererOptions(
html.WithUnsafe(),
),
goldmark.WithParserOptions(
parser.WithAutoHeadingID(),
),
goldmark.WithExtensions(
extension.Table,
extension.Strikethrough,
extension.Footnote,
extension.Typographer,
extension.Linkify,
// Emojis
emoji.New(
emoji.WithEmojis(emojiGoLib()),
),
),
}
defaultMarkdown = goldmark.New(append(defaultGoldmarkOptions, goldmark.WithExtensions(&customExtension{absoluteLinks: false}))...)
absoluteMarkdown = goldmark.New(append(defaultGoldmarkOptions, goldmark.WithExtensions(&customExtension{absoluteLinks: true}))...)
}
func renderMarkdown(source string, absoluteLinks bool) (rendered []byte, err error) {
var buffer bytes.Buffer
if absoluteLinks {
err = absoluteMarkdown.Convert([]byte(source), &buffer)
} else {
err = defaultMarkdown.Convert([]byte(source), &buffer)
}
return buffer.Bytes(), err
}
// Extensions etc...
// All emojis from emoji lib
func emojiGoLib() definition.Emojis {
if emojilib == nil {
var emojis []definition.Emoji
for shotcode, e := range kemoji.CodeMap() {
emojis = append(emojis, definition.NewEmoji(e, []rune(e), strings.ReplaceAll(shotcode, ":", "")))
}
emojilib = definition.NewEmojis(emojis...)
}
return emojilib
}
// Links
type customExtension struct {
absoluteLinks bool
}
func (l *customExtension) Extend(m goldmark.Markdown) {
m.Renderer().AddOptions(renderer.WithNodeRenderers(
util.Prioritized(&customRenderer{
absoluteLinks: l.absoluteLinks,
}, 500),
))
}
type customRenderer struct {
absoluteLinks bool
}
func (c *customRenderer) RegisterFuncs(r renderer.NodeRendererFuncRegisterer) {
r.Register(ast.KindLink, c.renderLink)
r.Register(ast.KindImage, c.renderImage)
}
func (c *customRenderer) renderLink(w util.BufWriter, _ []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
if entering {
n := node.(*ast.Link)
_, _ = w.WriteString("<a href=\"")
// Make URL absolute if it's relative
newDestination := util.URLEscape(n.Destination, true)
if c.absoluteLinks && bytes.HasPrefix(newDestination, []byte("/")) {
_, _ = w.Write(util.EscapeHTML([]byte(appConfig.Server.PublicAddress)))
}
_, _ = w.Write(util.EscapeHTML(newDestination))
_, _ = w.WriteRune('"')
// Open external links (links that start with "http") in new tab
if bytes.HasPrefix(n.Destination, []byte("http")) {
_, _ = w.WriteString(` target="_blank" rel="noopener"`)
}
// Title
if n.Title != nil {
_, _ = w.WriteString(" title=\"")
_, _ = w.Write(n.Title)
_, _ = w.WriteRune('"')
}
_, _ = w.WriteRune('>')
} else {
_, _ = w.WriteString("</a>")
}
return ast.WalkContinue, nil
}
func (c *customRenderer) renderImage(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
n := node.(*ast.Image)
// Make URL absolute if it's relative
destination := util.URLEscape(n.Destination, true)
if bytes.HasPrefix(destination, []byte("/")) {
destination = util.EscapeHTML(append([]byte(appConfig.Server.PublicAddress), destination...))
} else {
destination = util.EscapeHTML(destination)
}
_, _ = w.WriteString("<a href=\"")
_, _ = w.Write(destination)
_, _ = w.WriteString("\">")
_, _ = w.WriteString("<img src=\"")
_, _ = w.Write(destination)
_, _ = w.WriteString("\" alt=\"")
_, _ = w.Write(util.EscapeHTML(n.Text(source)))
_ = w.WriteByte('"')
_, _ = w.WriteString(" loading=\"lazy\"")
if n.Title != nil {
_, _ = w.WriteString(" title=\"")
_, _ = w.Write(n.Title)
_ = w.WriteByte('"')
}
_, _ = w.WriteString("></a>")
return ast.WalkSkipChildren, nil
}