From 0d6d889dfe32f793f63027e1d773aebe65c38c6f Mon Sep 17 00:00:00 2001
From: A Farzat <a@farzat.xyz>
Date: Sun, 7 Jun 2026 19:57:48 +0300
Subject: Start adding shebang filetype detection

---
 src/renderer.rs | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)

(limited to 'src/renderer.rs')

diff --git a/src/renderer.rs b/src/renderer.rs
index 14d30d6..164012e 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -64,7 +64,7 @@ impl<W: Write> Renderer<W> {
     fn write_file(&mut self, filename: &Path, contents: &str) -> std::io::Result<()> {
         let name = display_path(filename);
         let fence = outer_backticks(contents);
-        let language = detect_language(filename);
+        let language = detect_language(filename, contents);
         self.log_file_render(filename);
         writeln!(self.output)?;
         writeln!(self.output, "## File: {}", name)?;
@@ -142,7 +142,7 @@ fn human_readable_size(bytes: u64) -> String {
     }
 }
 
-fn detect_language(filename: &Path) -> &'static str {
+fn detect_language(filename: &Path, contents: &str) -> &'static str {
     let ext = filename
         .extension()
         .and_then(|e| e.to_str())
@@ -152,7 +152,14 @@ fn detect_language(filename: &Path) -> &'static str {
         Some("rs") => "rust",
         Some("py") => "python",
         Some("json") => "json",
-        _ => "",
+        _ => {
+            if let Some(first_line) = contents.lines().next()
+                && first_line.contains("python")
+            {
+                return "python";
+            }
+            ""
+        }
     }
 }
 
@@ -245,6 +252,18 @@ mod tests {
         assert_eq!(String::from_utf8(output).unwrap(), expected);
     }
 
+    #[test]
+    fn txt_file_has_no_language_fence() {
+        let mut output = Vec::new();
+        let mut renderer = Renderer::new(&mut output);
+
+        let input = Cursor::new("hello world");
+        renderer.render_file(Path::new("hello.txt"), input).unwrap();
+        let expected = "\n## File: hello.txt\n```\nhello world\n```\n";
+
+        assert_eq!(String::from_utf8(output).unwrap(), expected);
+    }
+
     #[test]
     fn python_file_has_python_language_fence() {
         let mut output = Vec::new();
@@ -281,6 +300,18 @@ mod tests {
         assert_eq!(String::from_utf8(output).unwrap(), expected);
     }
 
+    #[test]
+    fn python_file_detected_from_shebang() {
+        let mut output = Vec::new();
+        let mut renderer = Renderer::new(&mut output);
+
+        let input = Cursor::new("#! /bin/python3\nprint('hello')");
+        renderer.render_file(Path::new("hello"), input).unwrap();
+        let expected = "\n## File: hello\n```python\n#! /bin/python3\nprint('hello')\n```\n";
+
+        assert_eq!(String::from_utf8(output).unwrap(), expected);
+    }
+
     #[test]
     fn renderer_places_placeholder_for_large_files_by_default() {
         let mut output = Vec::new();
-- 
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