From 746ef00eba20d9d106a354d5bf4e559b4230920d Mon Sep 17 00:00:00 2001
From: eti <eti@eti.tf>
Date: Tue, 2 Jun 2026 17:26:34 +0200
Subject: [PATCH] appview/pages: use proper html parsing in
 splitCodeBlockSegments
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

replace hand-rolled string scanning with golang.org/x/net/html
ParseFragment, fixing three infinite-loop paths that triggered on
malformed/unclosed <pre> tags and an off-by-one in line counting
(chroma always emits a trailing newline, so the old +1 overcounted
every code block by one line)

also remove the unused "markdown" template func — all prose rendering
goes through markdownSegments, readme, or description

Signed-off-by: eti <eti@eti.tf>
---
 appview/pages/funcmap.go | 113 +++++++++++++++++----------------------
 1 file changed, 48 insertions(+), 65 deletions(-)

diff --git a/appview/pages/funcmap.go b/appview/pages/funcmap.go
index 4997d0bb..58f2560c 100644
--- a/appview/pages/funcmap.go
+++ b/appview/pages/funcmap.go
@@ -29,6 +29,8 @@ import (
 	"github.com/go-enry/go-enry/v2"
 	"github.com/yuin/goldmark"
 	emoji "github.com/yuin/goldmark-emoji"
+	htmlparse "golang.org/x/net/html"
+	"golang.org/x/net/html/atom"
 	"tangled.org/core/appview/cache"
 	"tangled.org/core/appview/db"
 	"tangled.org/core/appview/models"
@@ -305,13 +307,6 @@ func (p *Pages) funcMap() template.FuncMap {
 			}
 			return v.Slice(0, min(n, v.Len())).Interface()
 		},
-		"markdown": func(text string) template.HTML {
-			rctx := p.rctx.Clone()
-			rctx.RendererType = markup.RendererTypeDefault
-			htmlString := rctx.RenderMarkdown(text)
-			sanitized := rctx.SanitizeDefault(htmlString)
-			return template.HTML(sanitized)
-		},
 		"markdownSegments": func(text string) []MarkdownSegment {
 			rctx := p.rctx.Clone()
 			rctx.RendererType = markup.RendererTypeDefault
@@ -638,71 +633,59 @@ func (p *Pages) AvatarUrl(actor, size string) string {
 	return baseUrl
 }
 
-func splitCodeBlockSegments(html string) []MarkdownSegment {
-	var segments []MarkdownSegment
-	remaining := html
-	closeTag := `</pre>`
-
-	for {
-		idx := strings.Index(remaining, `<pre`)
-		if idx == -1 {
-			if remaining != "" {
-				segments = append(segments, MarkdownSegment{HTML: template.HTML(remaining)})
-			}
-			break
-		}
-		openEnd := strings.Index(remaining[idx:], `>`)
-		if openEnd == -1 {
-			remaining = remaining[idx:]
-			continue
-		}
-		openEnd += idx
-		openTag := remaining[idx : openEnd+1]
+func splitCodeBlockSegments(rawHTML string) []MarkdownSegment {
+	nodes, err := htmlparse.ParseFragment(strings.NewReader(rawHTML), &htmlparse.Node{
+		Type:     htmlparse.ElementNode,
+		Data:     "body",
+		DataAtom: atom.Body,
+	})
+	if err != nil {
+		return []MarkdownSegment{{HTML: template.HTML(rawHTML)}}
+	}
 
-		if strings.Contains(openTag, `mermaid`) {
-			closeIdx := strings.Index(remaining[openEnd+1:], closeTag)
-			if closeIdx == -1 {
-				remaining = remaining[idx:]
-				continue
+	var segments []MarkdownSegment
+	var buf strings.Builder
+	for _, n := range nodes {
+		if n.Type == htmlparse.ElementNode && n.Data == "pre" {
+			if buf.Len() > 0 {
+				segments = append(segments, MarkdownSegment{HTML: template.HTML(buf.String())})
+				buf.Reset()
+			}
+			_ = htmlparse.Render(&buf, n)
+			isMermaid := false
+			for _, attr := range n.Attr {
+				if attr.Key == "class" && strings.Contains(attr.Val, "mermaid") {
+					isMermaid = true
+					break
+				}
 			}
-			closeIdx += openEnd + 1
-
-			if idx > 0 {
-				segments = append(segments, MarkdownSegment{HTML: template.HTML(remaining[:idx])})
+			seg := MarkdownSegment{HTML: template.HTML(buf.String())}
+			if !isMermaid {
+				seg.IsCode = true
+				seg.Lines = countTextNewlines(n)
 			}
-
-			preEnd := closeIdx + len(closeTag)
-			preHTML := remaining[idx:preEnd]
-			segments = append(segments, MarkdownSegment{
-				HTML: template.HTML(preHTML),
-			})
-			remaining = remaining[preEnd:]
-			continue
-		}
-
-		closeIdx := strings.Index(remaining[openEnd+1:], closeTag)
-		if closeIdx == -1 {
-			remaining = remaining[idx:]
-			continue
+			segments = append(segments, seg)
+			buf.Reset()
+		} else {
+			_ = htmlparse.Render(&buf, n)
 		}
-		closeIdx += openEnd + 1
+	}
+	if buf.Len() > 0 {
+		segments = append(segments, MarkdownSegment{HTML: template.HTML(buf.String())})
+	}
+	return segments
+}
 
-		if idx > 0 {
-			segments = append(segments, MarkdownSegment{HTML: template.HTML(remaining[:idx])})
+func countTextNewlines(n *htmlparse.Node) int {
+	count := 0
+	for c := n.FirstChild; c != nil; c = c.NextSibling {
+		if c.Type == htmlparse.TextNode {
+			count += strings.Count(c.Data, "\n")
+		} else {
+			count += countTextNewlines(c)
 		}
-
-		preEnd := closeIdx + len(closeTag)
-		preHTML := remaining[idx:preEnd]
-		content := remaining[openEnd+1 : closeIdx]
-		lines := strings.Count(content, "\n") + 1
-		segments = append(segments, MarkdownSegment{
-			HTML:   template.HTML(preHTML),
-			IsCode: true,
-			Lines:  lines,
-		})
-		remaining = remaining[preEnd:]
 	}
-	return segments
+	return count
 }
 
 func (p *Pages) icon(name string, classes []string) (template.HTML, error) {
-- 
2.51.2