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package markup
import (
"bytes"
"fmt"
"io"
"net/url"
"path/filepath"
"strings"
"golang.org/x/net/html"
"go.jolheiser.com/ugit/internal/git"
chromahtml "github.com/alecthomas/chroma/v2/formatters/html"
"github.com/yuin/goldmark"
emoji "github.com/yuin/goldmark-emoji"
highlighting "github.com/yuin/goldmark-highlighting/v2"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/extension"
"github.com/yuin/goldmark/parser"
goldmarkhtml "github.com/yuin/goldmark/renderer/html"
"github.com/yuin/goldmark/text"
"github.com/yuin/goldmark/util"
)
var markdown = goldmark.New(
goldmark.WithRendererOptions(
goldmarkhtml.WithUnsafe(),
),
goldmark.WithParserOptions(
parser.WithAutoHeadingID(),
parser.WithASTTransformers(
util.Prioritized(astTransformer{}, 100),
),
),
goldmark.WithExtensions(
extension.GFM,
emoji.Emoji,
highlighting.NewHighlighting(
highlighting.WithStyle("catppuccin-mocha"),
highlighting.WithFormatOptions(
chromahtml.WithClasses(true),
),
),
),
)
// Readme transforms a readme, potentially from markdown, into HTML
func Readme(repo *git.Repo, ref, path string) (string, error) {
var readme string
var err error
for _, md := range []string{"README.md", "readme.md"} {
readme, err = repo.FileContent(ref, filepath.Join(path, md))
if err == nil {
break
}
}
if readme != "" {
ctx := parser.NewContext()
mdCtx := markdownContext{
repo: repo.Name(),
ref: ref,
path: path,
}
ctx.Set(renderContextKey, mdCtx)
var buf bytes.Buffer
if err := markdown.Convert([]byte(readme), &buf, parser.WithContext(ctx)); err != nil {
return "", err
}
var out bytes.Buffer
if err := postProcess(buf.String(), mdCtx, &out); err != nil {
return "", err
}
return out.String(), nil
}
for _, md := range []string{"README.txt", "README", "readme.txt", "readme"} {
readme, err = repo.FileContent(ref, filepath.Join(path, md))
if err == nil {
return readme, nil
}
}
return "", nil
}
var renderContextKey = parser.NewContextKey()
type markdownContext struct {
repo string
ref string
path string
}
type astTransformer struct{}
// Transform does two main things
// 1. Changes images to work relative to the source and wraps them in links
// 2. Changes links to work relative to the source
func (a astTransformer) Transform(node *ast.Document, _ text.Reader, pc parser.Context) {
_ = ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
ctx := pc.Get(renderContextKey).(markdownContext)
switch v := n.(type) {
case *ast.Image:
link := v.Destination
if len(link) > 0 && !bytes.HasPrefix(link, []byte("http")) {
v.Destination = []byte(resolveLink(ctx.repo, ctx.ref, ctx.path, string(link)) + "?raw&pretty")
}
parent := n.Parent()
if _, ok := parent.(*ast.Link); !ok && parent != nil {
next := n.NextSibling()
wrapper := ast.NewLink()
wrapper.Destination = v.Destination
wrapper.Title = v.Title
wrapper.SetAttributeString("target", []byte("_blank"))
img := ast.NewImage(ast.NewLink())
img.Destination = link
img.Title = v.Title
for _, attr := range v.Attributes() {
img.SetAttribute(attr.Name, attr.Value)
}
for child := v.FirstChild(); child != nil; {
nextChild := child.NextSibling()
img.AppendChild(img, child)
child = nextChild
}
wrapper.AppendChild(wrapper, img)
wrapper.SetNextSibling(next)
parent.ReplaceChild(parent, n, wrapper)
v.SetNextSibling(next)
}
case *ast.Link:
link := v.Destination
if len(link) > 0 && !bytes.HasPrefix(link, []byte("http")) && link[0] != '#' && !bytes.HasPrefix(link, []byte("mailto")) {
v.Destination = []byte(resolveLink(ctx.repo, ctx.ref, ctx.path, string(link)))
}
}
return ast.WalkContinue, nil
})
}
func postProcess(in string, ctx markdownContext, out io.Writer) error {
node, err := html.Parse(strings.NewReader("<html><body>" + in + "</body></html"))
if err != nil {
return err
}
if node.Type == html.DocumentNode {
node = node.FirstChild
}
process(ctx, node)
renderNodes := make([]*html.Node, 0)
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 {
renderNodes = append(renderNodes, child)
child = child.NextSibling
}
} else {
renderNodes = append(renderNodes, node)
}
}
for _, node := range renderNodes {
if err := html.Render(out, node); err != nil {
return err
}
}
return nil
}
func process(ctx markdownContext, node *html.Node) {
if node.Type == html.ElementNode && node.Data == "img" {
for i, attr := range node.Attr {
if attr.Key != "src" {
continue
}
if len(attr.Val) > 0 && !strings.HasPrefix(attr.Val, "http") && !strings.HasPrefix(attr.Val, "data:image/") {
attr.Val = resolveLink(ctx.repo, ctx.ref, ctx.path, attr.Val) + "?raw&pretty"
}
node.Attr[i] = attr
}
}
for n := node.FirstChild; n != nil; n = n.NextSibling {
process(ctx, n)
}
}
func resolveLink(repo, ref, path, link string) string {
baseURL, err := url.Parse(fmt.Sprintf("/%s/tree/%s/%s", repo, ref, path))
if err != nil {
return ""
}
linkURL, err := url.Parse(link)
if err != nil {
return ""
}
return baseURL.ResolveReference(linkURL).String()
}
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