hicli/html: fix extra newlines when copying code blocks

pkg/hicli/html.go

@@ -625,6 +625,20 @@ var CodeBlockFormatter = chromahtml.New(
 	chromahtml.WithLineNumbers(true),
 )
 
+type lineRewriter struct {
+	w *strings.Builder
+}
+
+var lineNumberRewriter = regexp.MustCompile(`<span class="ln">(\s*\d+)</span>`)
+var lineNumberReplacement = []byte(`<span class="ln" data-linenum="$1"></span>`)
+
+func (lr *lineRewriter) Write(p []byte) (n int, err error) {
+	n = len(p)
+	p = lineNumberRewriter.ReplaceAll(p, lineNumberReplacement)
+	lr.w.Write(p)
+	return
+}
+
 func writeCodeBlock(w *strings.Builder, language string, block *strings.Builder) {
 	lexer := lexers.Get(language)
 	if lexer == nil {
@@ -642,7 +656,7 @@ func writeCodeBlock(w *strings.Builder, language string, block *strings.Builder)
 		w.WriteString("</code></pre>")
 		return
 	}
-	err = CodeBlockFormatter.Format(w, styles.Fallback, iter)
+	err = CodeBlockFormatter.Format(&lineRewriter{w}, styles.Fallback, iter)
 	if err != nil {
 		// This should never fail
 		panic(err)

pkg/hicli/sync.go

@@ -430,7 +430,7 @@ func (h *HiClient) calculateLocalContent(ctx context.Context, dbEvt *database.Ev
 	return nil, nil
 }
 
-const CurrentHTMLSanitizerVersion = 6
+const CurrentHTMLSanitizerVersion = 7
 
 func (h *HiClient) ReprocessExistingEvent(ctx context.Context, evt *database.Event) {
 	if (evt.Type != event.EventMessage.Type && evt.DecryptedType != event.EventMessage.Type) ||

web/src/ui/timeline/content/index.css

@@ -113,6 +113,15 @@ div.html-body {
 
 		&.chroma {
 			background-color: var(--codeblock-background-color);
+
+			span.line > span.ln {
+				-webkit-user-select: initial;
+				user-select: initial;
+
+				&::before {
+					content: attr(data-linenum);
+				}
+			}
 		}
 	}