mugit/internal/mdx/relative_link.go (view raw)
| 1 | package mdx |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "fmt" |
| 6 | "net/url" |
| 7 | "path" |
| 8 | "path/filepath" |
| 9 | "regexp" |
| 10 | "strings" |
| 11 | |
| 12 | "github.com/yuin/goldmark" |
| 13 | "github.com/yuin/goldmark/ast" |
| 14 | "github.com/yuin/goldmark/parser" |
| 15 | "github.com/yuin/goldmark/renderer" |
| 16 | "github.com/yuin/goldmark/text" |
| 17 | "github.com/yuin/goldmark/util" |
| 18 | ) |
| 19 | |
| 20 | var ( |
| 21 | repoNameKey = parser.NewContextKey() |
| 22 | baseDirKey = parser.NewContextKey() |
| 23 | ) |
| 24 | |
| 25 | func NewRelativeLinkCtx(repoName, readmePath string) parser.ParseOption { |
| 26 | ctx := parser.NewContext() |
| 27 | ctx.Set(repoNameKey, repoName) |
| 28 | ctx.Set(baseDirKey, filepath.Dir(readmePath)) |
| 29 | return parser.WithContext(ctx) |
| 30 | } |
| 31 | |
| 32 | var RelativeLink = &relativeLink{} |
| 33 | |
| 34 | type relativeLink struct{} |
| 35 | |
| 36 | func (e *relativeLink) Extend(m goldmark.Markdown) { |
| 37 | m.Parser().AddOptions( |
| 38 | parser.WithASTTransformers(util.Prioritized(&relinkTransformer{}, 100)), |
| 39 | ) |
| 40 | m.Renderer().AddOptions( |
| 41 | renderer.WithNodeRenderers(util.Prioritized(&rawBlockRenderer{}, 100)), |
| 42 | ) |
| 43 | } |
| 44 | |
| 45 | type rawBlock struct { |
| 46 | ast.BaseBlock |
| 47 | data []byte |
| 48 | } |
| 49 | |
| 50 | var rawBlockKind = ast.NewNodeKind("RawBlock") |
| 51 | |
| 52 | func (r *rawBlock) Kind() ast.NodeKind { return rawBlockKind } |
| 53 | func (r *rawBlock) Dump(_ []byte, _ int) {} |
| 54 | |
| 55 | type rawBlockRenderer struct{} |
| 56 | |
| 57 | func (r *rawBlockRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) { |
| 58 | reg.Register(rawBlockKind, func(w util.BufWriter, _ []byte, node ast.Node, entering bool) (ast.WalkStatus, error) { |
| 59 | if entering { |
| 60 | w.Write(node.(*rawBlock).data) |
| 61 | } |
| 62 | return ast.WalkContinue, nil |
| 63 | }) |
| 64 | } |
| 65 | |
| 66 | type relinkTransformer struct{} |
| 67 | |
| 68 | func (t *relinkTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) { |
| 69 | repoName, _ := pc.Get(repoNameKey).(string) |
| 70 | baseDir, _ := pc.Get(baseDirKey).(string) |
| 71 | |
| 72 | _ = ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) { |
| 73 | if !entering { |
| 74 | return ast.WalkContinue, nil |
| 75 | } |
| 76 | |
| 77 | switch v := n.(type) { |
| 78 | case *ast.Image: |
| 79 | if rewritten := t.rewriteDest(v.Destination, repoName, baseDir); rewritten != nil { |
| 80 | v.Destination = rewritten |
| 81 | } |
| 82 | case *ast.Link: |
| 83 | if rewritten := t.rewriteDest(v.Destination, repoName, baseDir); rewritten != nil { |
| 84 | v.Destination = rewritten |
| 85 | } |
| 86 | case *ast.RawHTML: |
| 87 | var buf []byte |
| 88 | for i := 0; i < v.Segments.Len(); i++ { |
| 89 | buf = append(buf, reader.Value(v.Segments.At(i))...) |
| 90 | } |
| 91 | updated := t.rewriteSrc(buf, repoName, baseDir) |
| 92 | if !bytes.Equal(updated, buf) { |
| 93 | str := ast.NewString(updated) |
| 94 | str.SetRaw(true) |
| 95 | n.Parent().ReplaceChild(n.Parent(), n, str) |
| 96 | } |
| 97 | case *ast.HTMLBlock: |
| 98 | var buf []byte |
| 99 | for i := 0; i < v.Lines().Len(); i++ { |
| 100 | buf = append(buf, reader.Value(v.Lines().At(i))...) |
| 101 | } |
| 102 | updated := t.rewriteSrc(buf, repoName, baseDir) |
| 103 | if !bytes.Equal(updated, buf) { |
| 104 | n.Parent().ReplaceChild(n.Parent(), n, &rawBlock{data: updated}) |
| 105 | } |
| 106 | } |
| 107 | |
| 108 | return ast.WalkContinue, nil |
| 109 | }) |
| 110 | } |
| 111 | |
| 112 | func (t *relinkTransformer) rewriteDest(dest []byte, repoName, baseDir string) []byte { |
| 113 | urlStr := string(dest) |
| 114 | if strings.HasPrefix(urlStr, "http://") || |
| 115 | strings.HasPrefix(urlStr, "https://") || |
| 116 | strings.HasPrefix(urlStr, "//") || |
| 117 | strings.HasPrefix(urlStr, "#") || |
| 118 | strings.HasPrefix(urlStr, "mailto:") || |
| 119 | strings.HasPrefix(urlStr, "data:") { |
| 120 | return nil |
| 121 | } |
| 122 | urlStr = strings.TrimPrefix(urlStr, "./") |
| 123 | |
| 124 | var absPath string |
| 125 | if after, ok := strings.CutPrefix(urlStr, "/"); ok { |
| 126 | absPath = after |
| 127 | } else { |
| 128 | if baseDir == "" || baseDir == "." { |
| 129 | absPath = urlStr |
| 130 | } else { |
| 131 | absPath = path.Join(baseDir, urlStr) |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | absPath = strings.TrimPrefix(path.Clean(absPath), "/") |
| 136 | |
| 137 | // FIXME: hardcoded ref and link |
| 138 | return fmt.Appendf(nil, "/%s/blob/HEAD/%s?raw=true", url.PathEscape(repoName), absPath) |
| 139 | } |
| 140 | |
| 141 | var imgSrcRe = regexp.MustCompile(`src="([^"]*)"`) |
| 142 | |
| 143 | func (t *relinkTransformer) rewriteSrc(buf []byte, repoName, baseDir string) []byte { |
| 144 | return imgSrcRe.ReplaceAllFunc(buf, func(match []byte) []byte { |
| 145 | src := imgSrcRe.FindSubmatch(match)[1] |
| 146 | rewritten := t.rewriteDest(src, repoName, baseDir) |
| 147 | if rewritten == nil { |
| 148 | return match |
| 149 | } |
| 150 | return append([]byte(`src="`), append(rewritten, '"')...) |
| 151 | }) |
| 152 | } |