feat: Phase 1 critical gaps — gamification API, Razorpay checkout, Google OAuth, notifications

- Fix gamification endpoints to use Node.js server (app.eventifyplus.com)
- Replace 6 mock gamification methods with real API calls (dashboard, leaderboard, shop, redeem, submit)
- Add booking models, service, payment service (Razorpay), checkout provider
- Add 3-step CheckoutScreen with Razorpay native modal integration
- Add Google OAuth login (Flutter + Django backend)
- Add full notifications system (Django model + 3 endpoints + Flutter UI)
- Register CheckoutProvider, NotificationProvider in main.dart MultiProvider
- Wire notification bell in HomeScreen app bar
- Add razorpay_flutter ^1.3.7 and google_sign_in ^6.2.2 packages

lib/features/booking/models/booking_models.dart

@@ -0,0 +1,87 @@
+// lib/features/booking/models/booking_models.dart
+
+class TicketMetaModel {
+  final int id;
+  final int eventId;
+  final String ticketType;
+  final double price;
+  final int availableQuantity;
+  final String? description;
+
+  const TicketMetaModel({
+    required this.id,
+    required this.eventId,
+    required this.ticketType,
+    required this.price,
+    this.availableQuantity = 0,
+    this.description,
+  });
+
+  factory TicketMetaModel.fromJson(Map<String, dynamic> json) {
+    return TicketMetaModel(
+      id: (json['id'] as num?)?.toInt() ?? 0,
+      eventId: (json['event_id'] as num?)?.toInt() ?? (json['event'] as num?)?.toInt() ?? 0,
+      ticketType: json['ticket_type'] as String? ?? json['name'] as String? ?? '',
+      price: (json['price'] as num?)?.toDouble() ?? 0.0,
+      availableQuantity: (json['available_quantity'] as num?)?.toInt() ?? 0,
+      description: json['description'] as String?,
+    );
+  }
+}
+
+class CartItemModel {
+  final TicketMetaModel ticket;
+  int quantity;
+
+  CartItemModel({required this.ticket, this.quantity = 1});
+
+  double get subtotal => ticket.price * quantity;
+}
+
+class ShippingDetails {
+  final String name;
+  final String email;
+  final String phone;
+  final String? address;
+  final String? city;
+  final String? state;
+  final String? zipCode;
+
+  const ShippingDetails({
+    required this.name,
+    required this.email,
+    required this.phone,
+    this.address,
+    this.city,
+    this.state,
+    this.zipCode,
+  });
+
+  Map<String, dynamic> toJson() => {
+    'name': name,
+    'email': email,
+    'phone': phone,
+    if (address != null) 'address': address,
+    if (city != null) 'city': city,
+    if (state != null) 'state': state,
+    if (zipCode != null) 'zip_code': zipCode,
+  };
+}
+
+class OrderSummary {
+  final List<CartItemModel> items;
+  final double subtotal;
+  final double discount;
+  final double tax;
+  final double total;
+  final String? couponCode;
+
+  const OrderSummary({
+    required this.items,
+    required this.subtotal,
+    this.discount = 0,
+    this.tax = 0,
+    required this.total,
+    this.couponCode,
+  });
+}

lib/features/booking/providers/checkout_provider.dart

@@ -0,0 +1,147 @@
+// lib/features/booking/providers/checkout_provider.dart
+
+import 'package:flutter/foundation.dart';
+import '../../../core/utils/error_utils.dart';
+import '../models/booking_models.dart';
+import '../services/booking_service.dart';
+
+enum CheckoutStep { tickets, details, payment, confirmation }
+
+class CheckoutProvider extends ChangeNotifier {
+  final BookingService _service = BookingService();
+
+  // Event being booked
+  int? eventId;
+  String eventName = '';
+
+  // Step tracking
+  CheckoutStep currentStep = CheckoutStep.tickets;
+
+  // Ticket selection
+  List<TicketMetaModel> availableTickets = [];
+  List<CartItemModel> cart = [];
+
+  // Shipping
+  ShippingDetails? shippingDetails;
+
+  // Coupon
+  String? couponCode;
+
+  // Status
+  bool loading = false;
+  String? error;
+  String? paymentId;
+
+  /// Initialize checkout for an event.
+  Future<void> initForEvent(int eventId, String eventName) async {
+    this.eventId = eventId;
+    this.eventName = eventName;
+    currentStep = CheckoutStep.tickets;
+    cart = [];
+    shippingDetails = null;
+    couponCode = null;
+    paymentId = null;
+    error = null;
+    loading = true;
+    notifyListeners();
+
+    try {
+      availableTickets = await _service.getTicketMeta(eventId);
+    } catch (e) {
+      error = userFriendlyError(e);
+    } finally {
+      loading = false;
+      notifyListeners();
+    }
+  }
+
+  /// Add or update cart item.
+  void setTicketQuantity(TicketMetaModel ticket, int qty) {
+    cart.removeWhere((c) => c.ticket.id == ticket.id);
+    if (qty > 0) {
+      cart.add(CartItemModel(ticket: ticket, quantity: qty));
+    }
+    notifyListeners();
+  }
+
+  double get subtotal => cart.fold(0, (sum, item) => sum + item.subtotal);
+  double get total => subtotal; // expand with discount/tax later
+
+  bool get hasItems => cart.isNotEmpty;
+
+  /// Move to next step.
+  void nextStep() {
+    if (currentStep == CheckoutStep.tickets && hasItems) {
+      currentStep = CheckoutStep.details;
+    } else if (currentStep == CheckoutStep.details && shippingDetails != null) {
+      currentStep = CheckoutStep.payment;
+    }
+    notifyListeners();
+  }
+
+  /// Move to previous step.
+  void previousStep() {
+    if (currentStep == CheckoutStep.payment) {
+      currentStep = CheckoutStep.details;
+    } else if (currentStep == CheckoutStep.details) {
+      currentStep = CheckoutStep.tickets;
+    }
+    notifyListeners();
+  }
+
+  /// Set shipping details from form.
+  void setShipping(ShippingDetails details) {
+    shippingDetails = details;
+    notifyListeners();
+  }
+
+  /// Process checkout on backend.
+  Future<Map<String, dynamic>> processCheckout() async {
+    loading = true;
+    error = null;
+    notifyListeners();
+
+    try {
+      final tickets = cart.map((c) => {
+        'ticket_meta_id': c.ticket.id,
+        'quantity': c.quantity,
+      }).toList();
+
+      final res = await _service.processCheckout(
+        eventId: eventId!,
+        tickets: tickets,
+        shippingDetails: shippingDetails?.toJson() ?? {},
+        couponCode: couponCode,
+      );
+      return res;
+    } catch (e) {
+      error = userFriendlyError(e);
+      rethrow;
+    } finally {
+      loading = false;
+      notifyListeners();
+    }
+  }
+
+  /// Mark payment as complete.
+  void markPaymentSuccess(String id) {
+    paymentId = id;
+    currentStep = CheckoutStep.confirmation;
+    notifyListeners();
+  }
+
+  /// Reset checkout state.
+  void reset() {
+    eventId = null;
+    eventName = '';
+    currentStep = CheckoutStep.tickets;
+    availableTickets = [];
+    cart = [];
+    shippingDetails = null;
+    couponCode = null;
+    paymentId = null;
+    error = null;
+    loading = false;
+    notifyListeners();
+  }
+}

lib/features/booking/services/booking_service.dart

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+// lib/features/booking/services/booking_service.dart
+
+import '../../../core/api/api_client.dart';
+import '../../../core/api/api_endpoints.dart';
+import '../models/booking_models.dart';
+
+class BookingService {
+  final ApiClient _api = ApiClient();
+
+  /// Fetch available ticket types for an event.
+  Future<List<TicketMetaModel>> getTicketMeta(int eventId) async {
+    final res = await _api.post(
+      ApiEndpoints.ticketMetaList,
+      body: {'event_id': eventId},
+    );
+    final rawList = res['ticket_metas'] ?? res['tickets'] ?? res['data'] ?? [];
+    if (rawList is List) {
+      return rawList
+          .map((e) => TicketMetaModel.fromJson(Map<String, dynamic>.from(e as Map)))
+          .toList();
+    }
+    return [];
+  }
+
+  /// Add item to cart.
+  Future<Map<String, dynamic>> addToCart({
+    required int ticketMetaId,
+    required int quantity,
+  }) async {
+    return await _api.post(
+      ApiEndpoints.cartAdd,
+      body: {'ticket_meta_id': ticketMetaId, 'quantity': quantity},
+    );
+  }
+
+  /// Process checkout — creates booking + returns order ID for payment.
+  Future<Map<String, dynamic>> processCheckout({
+    required int eventId,
+    required List<Map<String, dynamic>> tickets,
+    required Map<String, dynamic> shippingDetails,
+    String? couponCode,
+  }) async {
+    return await _api.post(
+      ApiEndpoints.checkout,
+      body: {
+        'event_id': eventId,
+        'tickets': tickets,
+        'shipping': shippingDetails,
+        if (couponCode != null) 'coupon_code': couponCode,
+      },
+    );
+  }
+}

lib/features/booking/services/payment_service.dart

@@ -0,0 +1,67 @@
+// lib/features/booking/services/payment_service.dart
+
+import 'package:razorpay_flutter/razorpay_flutter.dart';
+import 'package:flutter/foundation.dart';
+
+typedef PaymentSuccessCallback = void Function(PaymentSuccessResponse response);
+typedef PaymentErrorCallback = void Function(PaymentFailureResponse response);
+typedef ExternalWalletCallback = void Function(ExternalWalletResponse response);
+
+class PaymentService {
+  late Razorpay _razorpay;
+
+  // Razorpay test key — matches web app
+  static const String _testKey = 'rzp_test_S49PVZmqAVoWSH';
+
+  PaymentSuccessCallback? onSuccess;
+  PaymentErrorCallback? onError;
+  ExternalWalletCallback? onExternalWallet;
+
+  void initialize({
+    required PaymentSuccessCallback onSuccess,
+    required PaymentErrorCallback onError,
+    ExternalWalletCallback? onExternalWallet,
+  }) {
+    _razorpay = Razorpay();
+    this.onSuccess = onSuccess;
+    this.onError = onError;
+    this.onExternalWallet = onExternalWallet;
+
+    _razorpay.on(Razorpay.EVENT_PAYMENT_SUCCESS, _handleSuccess);
+    _razorpay.on(Razorpay.EVENT_PAYMENT_ERROR, _handleError);
+    _razorpay.on(Razorpay.EVENT_EXTERNAL_WALLET, _handleExternalWallet);
+  }
+
+  void openPayment({
+    required double amount,
+    required String email,
+    required String phone,
+    required String eventName,
+    String? orderId,
+  }) {
+    final options = <String, dynamic>{
+      'key': _testKey,
+      'amount': (amount * 100).toInt(), // paise
+      'currency': 'INR',
+      'name': 'Eventify',
+      'description': 'Ticket: $eventName',
+      'prefill': {
+        'email': email,
+        'contact': phone,
+      },
+      'theme': {'color': '#0B63D6'},
+    };
+    if (orderId != null) options['order_id'] = orderId;
+
+    if (kDebugMode) debugPrint('PaymentService: opening Razorpay with amount=${amount * 100} paise');
+    _razorpay.open(options);
+  }
+
+  void _handleSuccess(PaymentSuccessResponse res) => onSuccess?.call(res);
+  void _handleError(PaymentFailureResponse res) => onError?.call(res);
+  void _handleExternalWallet(ExternalWalletResponse res) => onExternalWallet?.call(res);
+
+  void dispose() {
+    _razorpay.clear();
+  }
+}