mugit/internal/markdown/relink.go(view raw)
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package markdown
import (
"bytes"
"net/url"
"path"
"regexp"
"strings"
"github.com/yuin/goldmark"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/parser"
"github.com/yuin/goldmark/renderer"
"github.com/yuin/goldmark/text"
"github.com/yuin/goldmark/util"
)
type relativeLink struct{}
func (e *relativeLink) Extend(m goldmark.Markdown) {
m.Parser().AddOptions(parser.WithASTTransformers(util.Prioritized(&relLinkTransformer{}, 99)))
m.Renderer().AddOptions(renderer.WithNodeRenderers(util.Prioritized(&rawBlockRenderer{}, 100)))
}
type relLinkTransformer struct {
repoName string
repoRef string
baseDir string
}
func (m *relLinkTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) {
m.repoName, _ = pc.Get(repoNameKey).(string)
m.repoRef, _ = pc.Get(repoRefKey).(string)
m.baseDir, _ = pc.Get(baseDirKey).(string)
_ = ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
switch n := n.(type) {
case *ast.Link:
m.relativeLinkTransformer(n)
case *ast.Image:
m.imageFromRepoTransformer(n)
case *ast.RawHTML:
buf := m.segmentsToBytes(n.Segments, reader)
updated := m.rewriteSrc(buf)
if !bytes.Equal(updated, buf) {
s := ast.NewString(updated)
s.SetRaw(true)
n.Parent().ReplaceChild(n.Parent(), n, s)
}
case *ast.HTMLBlock:
buf := m.segmentsToBytes(n.Lines(), reader)
updated := m.rewriteSrc(buf)
if !bytes.Equal(updated, buf) {
n.Parent().ReplaceChild(n.Parent(), n, &rawBlock{data: updated})
}
}
return ast.WalkContinue, nil
})
}
func (m *relLinkTransformer) relativeLinkTransformer(link *ast.Link) {
dst := string(link.Destination)
if isAbsoluteURL(dst) {
return
}
act := m.path(dst)
link.Destination = []byte(path.Join("/", m.repoName, "tree", m.repoRef, act))
}
func (m *relLinkTransformer) imageFromRepoTransformer(img *ast.Image) {
img.Destination = []byte(m.imageFromRepo(
string(img.Destination)))
}
func (m *relLinkTransformer) imageFromRepo(dst string) string {
if isAbsoluteURL(dst) {
return dst
}
absPath := m.path(dst)
return path.Join("/", url.PathEscape(m.repoName), "blob", m.repoRef, absPath) +
"?raw=true"
}
func (m *relLinkTransformer) path(dst string) string {
if path.IsAbs(dst) {
return dst
}
return path.Join(m.baseDir, dst)
}
var imgSrcRe = regexp.MustCompile(`src="([^"]*)"`)
func (m *relLinkTransformer) rewriteSrc(buf []byte) []byte {
return imgSrcRe.ReplaceAllFunc(buf, func(match []byte) []byte {
start := bytes.IndexByte(match, '"') + 1
end := bytes.LastIndexByte(match, '"')
src := string(match[start:end])
return []byte(`src="` + m.imageFromRepo(src) + `"`)
})
}
func (m *relLinkTransformer) segmentsToBytes(segs *text.Segments, reader text.Reader) []byte {
var buf []byte
for i := 0; i < segs.Len(); i++ {
buf = append(buf, reader.Value(segs.At(i))...)
}
return buf
}
func isAbsoluteURL(link string) bool {
if strings.HasPrefix(link, "#") {
return true
}
u, err := url.Parse(link)
return err == nil && (u.Scheme != "" || strings.HasPrefix(link, "//"))
}
// row block
type rawBlock struct {
ast.BaseBlock
data []byte
}
var rawBlockKind = ast.NewNodeKind("RawBlock")
func (r *rawBlock) Kind() ast.NodeKind { return rawBlockKind }
func (r *rawBlock) Dump(_ []byte, _ int) {}
type rawBlockRenderer struct{}
func (r *rawBlockRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
reg.Register(rawBlockKind, func(w util.BufWriter, _ []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
if entering {
w.Write(node.(*rawBlock).data)
}
return ast.WalkContinue, nil
})
}
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