Add ShellCheck autofix

Author: overflowy

index.html

@@ -58,6 +58,13 @@ <h1 class="text-3xl font-semibold mb-2">Bash Script Tools</h1>
           >
             <span>Lint</span>
           </button>
+
+          <button
+            onclick="autofixCode()"
+            class="inline-flex items-center px-4 py-2 bg-zinc-900 text-zinc-100 rounded-md hover:bg-zinc-800 focus:outline-none focus:ring-2 focus:ring-zinc-700 transition-colors font-medium text-sm border border-zinc-800"
+          >
+            <span>Autofix</span>
+          </button>
         </div>
 
         <!-- Output Box -->
@@ -146,6 +153,28 @@ <h1 class="text-3xl font-semibold mb-2">Bash Script Tools</h1>
             '<div class="text-xs text-red-600 font-mono">Error running ShellCheck</div>';
         }
       }
+
+      async function autofixCode() {
+        const code = editor.getValue();
+
+        try {
+          const response = await fetch("/autofix", {
+            method: "POST",
+            headers: { "Content-Type": "application/x-www-form-urlencoded" },
+            body: "code=" + encodeURIComponent(code),
+          });
+
+          const fixedCode = await response.text();
+          const cursor = editor.getCursorPosition();
+          editor.setValue(fixedCode, -1);
+          editor.moveCursorToPosition(cursor);
+
+          // Run shellcheck again to update annotations
+          await checkCode();
+        } catch (error) {
+          console.error("Autofix error:", error);
+        }
+      }
     </script>
   </body>
 </html>

main.go

@@ -54,6 +54,7 @@ func main() {
 	http.HandleFunc("/", handleIndex)
 	http.HandleFunc("/format", handleFormat)
 	http.HandleFunc("/shellcheck", handleShellcheck)
+	http.HandleFunc("/autofix", handleAutofix)
 
 	port := getEnvOrDefault("PORT", "8080")
 	log.Printf("Server starting on http://localhost:%s", port)
@@ -221,6 +222,64 @@ func parseShellcheckOutput(output string) []Annotation {
 	return annotations
 }
 
+func handleAutofix(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	code := r.FormValue("code")
+	if code == "" {
+		w.Write([]byte(code))
+		return
+	}
+
+	// Create temporary file for shellcheck
+	tmpFile := filepath.Join(os.TempDir(), "script.sh")
+	if err := os.WriteFile(tmpFile, []byte(code), 0644); err != nil {
+		log.Printf("autofix error: %v", err)
+		w.Write([]byte(code))
+		return
+	}
+	defer os.Remove(tmpFile)
+
+	// Run shellcheck with --format=diff to get fixes
+	cmd := exec.Command(shellcheckPath, "-f", "diff", tmpFile)
+	var out, stderr bytes.Buffer
+	cmd.Stdout = &out
+	cmd.Stderr = &stderr
+	cmd.Run()
+
+	diff := out.String()
+	if diff == "" {
+		// No fixes available, return original code
+		w.Write([]byte(code))
+		return
+	}
+
+	// Apply the diff using patch
+	patchCmd := exec.Command("patch", tmpFile)
+	patchCmd.Stdin = bytes.NewBufferString(diff)
+	var patchStderr bytes.Buffer
+	patchCmd.Stderr = &patchStderr
+
+	if err := patchCmd.Run(); err != nil {
+		log.Printf("patch error: %v - %s", err, patchStderr.String())
+		w.Write([]byte(code))
+		return
+	}
+
+	// Read the fixed file
+	fixed, err := os.ReadFile(tmpFile)
+	if err != nil {
+		log.Printf("read error: %v", err)
+		w.Write([]byte(code))
+		return
+	}
+
+	w.Write(fixed)
+}
+
 func formatShellcheckHTML(output string) string {
 	if output == "" {
 		return `<div class="text-sm text-green-600">✓ No issues found</div>`