mugit @ 6e228d9192b98e484881b8e702734ae920511538

M internal/handlers/repo.go

@@ -19,6 +19,7 @@ "github.com/yuin/goldmark"
 	"github.com/yuin/goldmark/extension"
 	"github.com/yuin/goldmark/renderer/html"
 	"olexsmir.xyz/mugit/internal/git"
+	"olexsmir.xyz/mugit/internal/mdx"
 )
 
 func (h *handlers) indexHandler(w http.ResponseWriter, r *http.Request) {
@@ -408,10 +409,12 @@ goldmark.WithRendererOptions(html.WithUnsafe()),
 	goldmark.WithExtensions(
 		extension.GFM,
 		extension.Linkify,
+		mdx.RelativeLink,
 	))
 
 func (h *handlers) renderReadme(r *git.Repo) (template.HTML, error) {
-	if v, found := h.readmeCache.Get(r.Name()); found {
+	name := r.Name()
+	if v, found := h.readmeCache.Get(name); found {
 		return v, nil
 	}
 
@@ -432,7 +435,8 @@ if len(content) > 0 {
 			switch ext {
 			case ".md", ".markdown", ".mkd":
 				var buf bytes.Buffer
-				if cerr := markdown.Convert([]byte(content), &buf); cerr != nil {
+				if cerr := markdown.Convert([]byte(content), &buf,
+					mdx.NewRelativeLinkCtx(name, readme)); cerr != nil {
 					return "", cerr
 				}
 				readmeContents = template.HTML(buf.String())
@@ -443,6 +447,6 @@ break
 		}
 	}
 
-	h.readmeCache.Set(r.Name(), readmeContents)
+	h.readmeCache.Set(name, readmeContents)
 	return readmeContents, nil
 }

A internal/mdx/relative_link.go

@@ -0,0 +1,101 @@
+package mdx
+
+import (
+	"fmt"
+	"net/url"
+	"path"
+	"path/filepath"
+	"strings"
+
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var (
+	repoNameKey = parser.NewContextKey()
+	baseDirKey  = parser.NewContextKey()
+)
+
+func NewRelativeLinkCtx(repoName, readmePath string) parser.ParseOption {
+	ctx := parser.NewContext()
+	ctx.Set(repoNameKey, repoName)
+	ctx.Set(baseDirKey, filepath.Dir(readmePath))
+	return parser.WithContext(ctx)
+}
+
+var RelativeLink = &relativeLink{}
+
+type relativeLink struct{}
+
+func (e *relativeLink) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(
+		parser.WithASTTransformers(
+			util.Prioritized(&relinkTransformer{}, 100),
+		),
+	)
+}
+
+type relinkTransformer struct{}
+
+func (t *relinkTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) {
+	repoName, _ := pc.Get(repoNameKey).(string)
+	baseDir, _ := pc.Get(baseDirKey).(string)
+
+	if repoName == "" {
+		return
+	}
+
+	_ = ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
+		if !entering {
+			return ast.WalkContinue, nil
+		}
+
+		var dest *[]byte
+		switch v := n.(type) {
+		case *ast.Image:
+			dest = &v.Destination
+		case *ast.Link:
+			dest = &v.Destination
+		default:
+			return ast.WalkContinue, nil
+		}
+
+		urlStr := string(*dest)
+
+		// skip absolute URLs
+		if strings.HasPrefix(urlStr, "http://") ||
+			strings.HasPrefix(urlStr, "https://") ||
+			strings.HasPrefix(urlStr, "//") ||
+			strings.HasPrefix(urlStr, "#") ||
+			strings.HasPrefix(urlStr, "mailto:") ||
+			strings.HasPrefix(urlStr, "data:") {
+			return ast.WalkContinue, nil
+		}
+
+		urlStr = strings.TrimPrefix(urlStr, "./")
+
+		var absPath string
+		if after, ok := strings.CutPrefix(urlStr, "/"); ok {
+			absPath = after // abs from repo root
+		} else {
+			// relative to repo location
+			if baseDir == "" || baseDir == "." {
+				absPath = urlStr
+			} else {
+				absPath = path.Join(baseDir, urlStr)
+			}
+		}
+
+		absPath = path.Clean(absPath)
+		absPath = strings.TrimPrefix(absPath, "/")
+
+		// FIXME:hardcoded link
+		*dest = fmt.Appendf(nil, "/%s/blob/HEAD/%s?raw=true",
+			url.PathEscape(repoName), absPath)
+
+		return ast.WalkContinue, nil
+	})
+}