Added core data models, repositories, and utilities

lifetimer/lib/data/repositories/user_repository.dart

@@ -0,0 +1,83 @@
+import 'package:supabase_flutter/supabase_flutter.dart' as supabase;
+import '../models/user_model.dart' as app;
+import '../../core/errors/failure.dart';
+
+class UserRepository {
+  final supabase.SupabaseClient _client;
+
+  UserRepository(this._client);
+
+  Future<app.User> getProfile(String userId) async {
+    try {
+      final response = await _client
+          .from('users')
+          .select()
+          .eq('id', userId)
+          .single();
+
+      return app.User.fromJson(response);
+    } catch (e) {
+      throw _handleError(e);
+    }
+  }
+
+  Future<app.User> updateProfile({
+    required String userId,
+    String? username,
+    String? avatarUrl,
+    String? bio,
+    bool? isPublicProfile,
+  }) async {
+    try {
+      final updates = <String, dynamic>{};
+      if (username != null) updates['username'] = username;
+      if (avatarUrl != null) updates['avatar_url'] = avatarUrl;
+      if (bio != null) updates['bio'] = bio;
+      if (isPublicProfile != null) updates['is_public_profile'] = isPublicProfile;
+      updates['updated_at'] = DateTime.now().toIso8601String();
+
+      final response = await _client
+          .from('users')
+          .update(updates)
+          .eq('id', userId)
+          .select()
+          .single();
+
+      return app.User.fromJson(response);
+    } catch (e) {
+      throw _handleError(e);
+    }
+  }
+
+  Future<bool> isUsernameAvailable(String username) async {
+    try {
+      final response = await _client
+          .from('users')
+          .select('id')
+          .eq('username', username)
+          .maybeSingle();
+
+      return response == null;
+    } catch (e) {
+      throw _handleError(e);
+    }
+  }
+
+  Future<void> deleteAccount(String userId) async {
+    try {
+      await _client.from('users').delete().eq('id', userId);
+    } catch (e) {
+      throw _handleError(e);
+    }
+  }
+
+  Failure _handleError(dynamic error) {
+    if (error is supabase.PostgrestException) {
+      if (error.code == '23505') {
+        return const ValidationFailure('Username already taken');
+      }
+      return ServerFailure(error.message);
+    }
+    return UnknownFailure(error.toString());
+  }
+}