feat(data-connect): Implement DataConnectService for centralized data operations and refactor ShiftsRepositoryImpl to utilize the new service

apps/mobile/packages/data_connect/lib/krow_data_connect.dart

@@ -13,6 +13,7 @@ export 'src/session/client_session_store.dart';
 
 // Export the generated Data Connect SDK
 export 'src/dataconnect_generated/generated.dart';
+export 'src/services/data_connect_service.dart';
 
 export 'src/session/staff_session_store.dart';
 export 'src/mixins/data_error_handler.dart';

apps/mobile/packages/data_connect/lib/src/services/data_connect_service.dart

@@ -0,0 +1,104 @@
+import 'dart:async';
+
+import 'package:firebase_auth/firebase_auth.dart' as firebase_auth;
+import 'package:firebase_data_connect/firebase_data_connect.dart' as fdc;
+import 'package:krow_core/core.dart';
+
+import '../../krow_data_connect.dart' as dc;
+import '../mixins/data_error_handler.dart';
+
+/// A centralized service for interacting with Firebase Data Connect.
+///
+/// This service provides common utilities and context management for all repositories.
+class DataConnectService with DataErrorHandler {
+  DataConnectService._();
+
+  /// The singleton instance of the [DataConnectService].
+  static final DataConnectService instance = DataConnectService._();
+
+  /// The Data Connect connector used for data operations.
+  final dc.ExampleConnector connector = dc.ExampleConnector.instance;
+
+  /// The Firebase Auth instance.
+  final firebase_auth.FirebaseAuth _auth = firebase_auth.FirebaseAuth.instance;
+
+  /// Cache for the current staff ID to avoid redundant lookups.
+  String? _cachedStaffId;
+
+  /// Gets the current staff ID from session store or persistent storage.
+  Future<String> getStaffId() async {
+    // 1. Check Session Store
+    final dc.StaffSession? session = dc.StaffSessionStore.instance.session;
+    if (session?.staff?.id != null) {
+      return session!.staff!.id;
+    }
+
+    // 2. Check Cache
+    if (_cachedStaffId != null) return _cachedStaffId!;
+
+    // 3. Fetch from Data Connect using Firebase UID
+    final firebase_auth.User? user = _auth.currentUser;
+    if (user == null) {
+      throw Exception('User is not authenticated');
+    }
+
+    try {
+      final fdc.QueryResult<
+        dc.GetStaffByUserIdData,
+        dc.GetStaffByUserIdVariables
+      >
+      response = await executeProtected(
+        () => connector.getStaffByUserId(userId: user.uid).execute(),
+      );
+
+      if (response.data.staffs.isNotEmpty) {
+        _cachedStaffId = response.data.staffs.first.id;
+        return _cachedStaffId!;
+      }
+    } catch (e) {
+      throw Exception('Failed to fetch staff ID from Data Connect: $e');
+    }
+
+    // 4. Fallback (should ideally not happen if DB is seeded)
+    return user.uid;
+  }
+
+  /// Converts a Data Connect timestamp/string/json to a [DateTime].
+  DateTime? toDateTime(dynamic t) {
+    if (t == null) return null;
+    DateTime? dt;
+    if (t is fdc.Timestamp) {
+      dt = t.toDateTime();
+    } else if (t is String) {
+      dt = DateTime.tryParse(t);
+    } else {
+      try {
+        dt = DateTime.tryParse(t.toJson() as String);
+      } catch (_) {
+        try {
+          dt = DateTime.tryParse(t.toString());
+        } catch (e) {
+          dt = null;
+        }
+      }
+    }
+
+    if (dt != null) {
+      return DateTimeUtils.toDeviceTime(dt);
+    }
+    return null;
+  }
+
+  /// Converts a [DateTime] to a Firebase Data Connect [Timestamp].
+  fdc.Timestamp toTimestamp(DateTime dateTime) {
+    final DateTime utc = dateTime.toUtc();
+    final int seconds = utc.millisecondsSinceEpoch ~/ 1000;
+    final int nanoseconds = (utc.microsecondsSinceEpoch % 1000000) * 1000;
+    return fdc.Timestamp(nanoseconds, seconds);
+  }
+
+  /// Clears the internal cache (e.g., on logout).
+  void clearCache() {
+    _cachedStaffId = null;
+  }
+}

apps/mobile/packages/data_connect/pubspec.yaml

@@ -16,3 +16,5 @@ dependencies:
   flutter_modular: ^6.3.0
   firebase_data_connect: ^0.2.2+2
   firebase_core: ^4.4.0
+  firebase_auth: ^6.1.4
+  krow_core: ^0.0.1