1 files changed, 41 insertions, 0 deletions
diff --git a/forged/internal/render/chroma.go b/forged/internal/render/chroma.go
new file mode 100644
index 0000000..64bfde0
--- /dev/null
+++ b/forged/internal/render/chroma.go
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+package render
+
+import (
+	"bytes"
+	"html/template"
+
+	chromaHTML "github.com/alecthomas/chroma/v2/formatters/html"
+	chromaLexers "github.com/alecthomas/chroma/v2/lexers"
+	chromaStyles "github.com/alecthomas/chroma/v2/styles"
+)
+
+// Highlight returns HTML with syntax highlighting for the given file content,
+// using Chroma. The lexer is selected based on the filename.
+// If tokenization or formatting fails, a fallback <pre> block is returned with the error.
+func Highlight(filename, content string) template.HTML {
+	lexer := chromaLexers.Match(filename)
+	if lexer == nil {
+		lexer = chromaLexers.Fallback
+	}
+
+	iterator, err := lexer.Tokenise(nil, content)
+	if err != nil {
+		return template.HTML("<pre>Error tokenizing file: " + err.Error() + "</pre>") //#nosec G203`
+	}
+
+	var buf bytes.Buffer
+	style := chromaStyles.Get("autumn")
+	formatter := chromaHTML.New(
+		chromaHTML.WithClasses(true),
+		chromaHTML.TabWidth(8),
+	)
+
+	if err := formatter.Format(&buf, style, iterator); err != nil {
+		return template.HTML("<pre>Error formatting file: " + err.Error() + "</pre>") //#nosec G203
+	}
+
+	return template.HTML(buf.Bytes()) //#nosec G203
+}