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import ( "bytes" "fmt" "io" "net/url" "path" "strings"
"github.com/microcosm-cc/bluemonday" "github.com/yuin/goldmark" "github.com/yuin/goldmark/ast" "github.com/yuin/goldmark/extension" "github.com/yuin/goldmark/parser" "github.com/yuin/goldmark/renderer/html" "github.com/yuin/goldmark/text" "github.com/yuin/goldmark/util" htmlparse "golang.org/x/net/html"
"tangled.sh/tangled.sh/core/appview/pages/repoinfo")
// RendererType defines the type of renderer to use based on contexttype RendererType int
const ( // RendererTypeRepoMarkdown is for repository documentation markdown files RendererTypeRepoMarkdown RendererType = iota // RendererTypeDefault is non-repo markdown, like issues/pulls/comments. RendererTypeDefault)
// RenderContext holds the contextual data for rendering markdown.// It can be initialized empty, and that'll skip any transformations.type RenderContext struct { CamoUrl string CamoSecret string repoinfo.RepoInfo IsDev bool RendererType RendererType}
func (rctx *RenderContext) RenderMarkdown(source string) string { md := goldmark.New( goldmark.WithExtensions(extension.GFM), goldmark.WithParserOptions( parser.WithAutoHeadingID(), ), goldmark.WithRendererOptions(html.WithUnsafe()), )
if rctx != nil { var transformers []util.PrioritizedValue
transformers = append(transformers, util.Prioritized(&MarkdownTransformer{rctx: rctx}, 10000))
md.Parser().AddOptions( parser.WithASTTransformers(transformers...), ) }
var buf bytes.Buffer if err := md.Convert([]byte(source), &buf); err != nil { return source }
var processed strings.Builder if err := postProcess(rctx, strings.NewReader(buf.String()), &processed); err != nil { return source }
return processed.String()}
func postProcess(ctx *RenderContext, input io.Reader, output io.Writer) error { node, err := htmlparse.Parse(io.MultiReader( strings.NewReader("<html><body>"), input, strings.NewReader("</body></html>"), )) if err != nil { return fmt.Errorf("failed to parse html: %w", err) }
if node.Type == htmlparse.DocumentNode { node = node.FirstChild }
visitNode(ctx, node)
newNodes := make([]*htmlparse.Node, 0, 5)
if node.Data == "html" { node = node.FirstChild for node != nil && node.Data != "body" { node = node.NextSibling } } if node != nil { if node.Data == "body" { child := node.FirstChild for child != nil { newNodes = append(newNodes, child) child = child.NextSibling } } else { newNodes = append(newNodes, node) } }
for _, node := range newNodes { if err := htmlparse.Render(output, node); err != nil { return fmt.Errorf("failed to render processed html: %w", err) } }
return nil}
func visitNode(ctx *RenderContext, node *htmlparse.Node) { switch node.Type { case htmlparse.ElementNode: if node.Data == "img" || node.Data == "source" { for i, attr := range node.Attr { if attr.Key != "src" { continue }
camoUrl, _ := url.Parse(ctx.CamoUrl) dstUrl, _ := url.Parse(attr.Val) if dstUrl.Host != camoUrl.Host { attr.Val = ctx.imageFromKnotTransformer(attr.Val) attr.Val = ctx.camoImageLinkTransformer(attr.Val) node.Attr[i] = attr } } }
for n := node.FirstChild; n != nil; n = n.NextSibling { visitNode(ctx, n) } default: }}
func (rctx *RenderContext) Sanitize(html string) string { policy := bluemonday.UGCPolicy()
// video policy.AllowElements("video") policy.AllowAttrs("controls").OnElements("video") policy.AllowElements("source") policy.AllowAttrs("src", "type").OnElements("source")
// centering content policy.AllowElements("center")
policy.AllowAttrs("align", "style", "width", "height").Globally() policy.AllowStyles( "margin", "padding", "text-align", "font-weight", "text-decoration", "padding-left", "padding-right", "padding-top", "padding-bottom", "margin-left", "margin-right", "margin-top", "margin-bottom", ) return policy.Sanitize(html)}
type MarkdownTransformer struct { rctx *RenderContext}
func (a *MarkdownTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) { _ = ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) { if !entering { return ast.WalkContinue, nil }
switch a.rctx.RendererType { case RendererTypeRepoMarkdown: switch n := n.(type) { case *ast.Link: a.rctx.relativeLinkTransformer(n) case *ast.Image: a.rctx.imageFromKnotAstTransformer(n) a.rctx.camoImageLinkAstTransformer(n) } case RendererTypeDefault: switch n := n.(type) { case *ast.Image: a.rctx.imageFromKnotAstTransformer(n) a.rctx.camoImageLinkAstTransformer(n) } }
return ast.WalkContinue, nil })}
func (rctx *RenderContext) relativeLinkTransformer(link *ast.Link) {
dst := string(link.Destination)
if isAbsoluteUrl(dst) { return }
actualPath := rctx.actualPath(dst)
newPath := path.Join("/", rctx.RepoInfo.FullName(), "tree", rctx.RepoInfo.Ref, actualPath) link.Destination = []byte(newPath)}
func (rctx *RenderContext) imageFromKnotTransformer(dst string) string { if isAbsoluteUrl(dst) { return dst }
scheme := "https" if rctx.IsDev { scheme = "http" }
actualPath := rctx.actualPath(dst)
parsedURL := &url.URL{ Scheme: scheme, Host: rctx.Knot, Path: path.Join("/", rctx.RepoInfo.OwnerDid, rctx.RepoInfo.Name, "raw", url.PathEscape(rctx.RepoInfo.Ref), actualPath), } newPath := parsedURL.String() return newPath}
func (rctx *RenderContext) imageFromKnotAstTransformer(img *ast.Image) { dst := string(img.Destination) img.Destination = []byte(rctx.imageFromKnotTransformer(dst))}
// actualPath decides when to join the file path with the// current repository directory (essentially only when the link// destination is relative. if it's absolute then we assume the// user knows what they're doing.)func (rctx *RenderContext) actualPath(dst string) string { if path.IsAbs(dst) { return dst }
return path.Join(rctx.CurrentDir, dst)}
func isAbsoluteUrl(link string) bool { parsed, err := url.Parse(link) if err != nil { return false } return parsed.IsAbs()}