tool: add diff program

tool/git_diff.dart

@@ -0,0 +1,67 @@
+// ignore_for_file: avoid_print
+
+import 'dart:io';
+
+import 'package:args/args.dart';
+
+void main(List<String> args) async {
+  // Parse args
+  final parser = ArgParser();
+
+  parser.addOption(
+    'dir',
+    abbr: 'd',
+    help: 'Directory to search for files with git diffs',
+  );
+
+  parser.addOption(
+    'file',
+    abbr: 'f',
+    help: 'File to check for git diff',
+  );
+
+  final results = parser.parse(args);
+
+  final dir = results['dir'] as String?;
+  final file = results['file'] as String?;
+
+  if (dir == null && file == null) {
+    print('Please provide a directory or file to check for git diff');
+    exit(1);
+  }
+
+  if (dir != null && file != null) {
+    print('Please provide only a directory or file to check for git diff');
+    exit(1);
+  }
+
+  if (dir != null) {
+    var result = await Process.run(
+      'git',
+      ['diff', '--name-only', '--relative', dir],
+    );
+
+    if (result.stdout.toString().isEmpty) {
+      print('No diff found in $dir');
+    } else {
+      print('Diff found in $dir');
+      print(result.stdout);
+      exit(1);
+    }
+  }
+
+  if (file != null) {
+    var result = await Process.run(
+      'git',
+      ['diff', '--name-only', file],
+    );
+
+    if (result.stdout.toString().isEmpty) {
+      print('No diff found in $file');
+    } else {
+      print('Diff found in $file');
+      print(result.stdout);
+      exit(1);
+    }
+  }
+}