Add GitHub Repository Validation to Leaderboard Submission Dialog (#5539)

frontend/lib/utils/uri_utility.dart

@@ -1,3 +1,6 @@
+import 'package:http/http.dart' as http;
+import 'dart:convert';
+
 class UriUtility {
   static bool isURL(String url) {
     // Validate if the URL string is empty, or contains spaces or invalid characters
@@ -44,4 +47,29 @@ class UriUtility {
     print('URL is valid.');
     return true;
   }
+
+  Future<bool> isValidGitHubRepo(String repoUrl) async {
+    var uri = Uri.parse(repoUrl);
+    if (uri.host != 'github.com') {
+      return false;
+    }
+
+    var segments = uri.pathSegments;
+    if (segments.length < 2) {
+      return false;
+    }
+
+    var user = segments[0];
+    var repo = segments[1];
+
+    var apiUri = Uri.https('api.github.com', '/repos/$user/$repo');
+
+    var response = await http.get(apiUri);
+    if (response.statusCode != 200) {
+      return false;
+    }
+
+    var data = json.decode(response.body);
+    return data is Map && data['full_name'] == '$user/$repo';
+  }
 }

frontend/lib/views/task_queue/leaderboard_submission_dialog.dart

@@ -44,14 +44,18 @@ class _LeaderboardSubmissionDialogState
     });
   }
 
-  void _validateAndSubmit() {
+  void _validateAndSubmit() async {
+    setState(() {
+      _teamNameError = null;
+      _repoUrlError = null;
+      _commitShaError = null;
+    });
+
     bool isValid = true;
 
     if (_teamNameController.text.isEmpty) {
       isValid = false;
       _teamNameError = 'Team Name is required';
-    } else {
-      _teamNameError = null;
     }
 
     if (_repoUrlController.text.isEmpty) {
@@ -60,20 +64,20 @@ class _LeaderboardSubmissionDialogState
     } else if (!UriUtility.isURL(_repoUrlController.text)) {
       isValid = false;
       _repoUrlError = 'Invalid URL format';
-    } else {
-      _repoUrlError = null;
+    } else if (!(await UriUtility()
+        .isValidGitHubRepo(_repoUrlController.text))) {
+      isValid = false;
+      _repoUrlError = 'Not a valid GitHub repository';
     }
 
     if (_commitShaController.text.isEmpty) {
       isValid = false;
       _commitShaError = 'Commit SHA is required';
-    } else {
-      _commitShaError = null;
     }
 
     if (isValid) {
       print('Valid leaderboard submission parameters!');
-      _saveToSharedPreferences();
+      await _saveToSharedPreferences();
       widget.onSubmit?.call(_teamNameController.text, _repoUrlController.text,
           _commitShaController.text);
       Navigator.of(context).pop();