import 'dart:async';
import 'package:flutter/material.dart';
import 'api.dart';

/// Service that polls the backend API for order status updates
/// Uses a simple polling approach (Option 2) with 30-second intervals
class OrderPollingService {
  static Timer? _pollingTimer;
  static int? _currentOrderId;
  static int? _lastKnownStatusId;
  static Function(OrderStatusUpdate)? _onStatusUpdate;

  /// Start polling for order status updates
  static void startPolling({
    required int orderId,
    required int initialStatusId,
    required Function(OrderStatusUpdate) onStatusUpdate,
  }) {
    print('[OrderPolling] 🔄 Starting polling for OrderID=$orderId, Status=$initialStatusId');

    // Stop any existing polling
    stopPolling();

    _currentOrderId = orderId;
    _lastKnownStatusId = initialStatusId;
    _onStatusUpdate = onStatusUpdate;

    // Poll every 30 seconds
    _pollingTimer = Timer.periodic(const Duration(seconds: 30), (_) {
      _checkForUpdate();
    });

    // Also check immediately
    _checkForUpdate();
  }

  /// Stop polling
  static void stopPolling() {
    print('[OrderPolling] ⏹️ Stopping polling');
    _pollingTimer?.cancel();
    _pollingTimer = null;
    _currentOrderId = null;
    _lastKnownStatusId = null;
    _onStatusUpdate = null;
  }

  /// Check if currently polling
  static bool get isPolling => _pollingTimer != null && _pollingTimer!.isActive;

  /// Get current order ID being polled
  static int? get currentOrderId => _currentOrderId;

  /// Internal method to check for updates
  static Future<void> _checkForUpdate() async {
    if (_currentOrderId == null || _lastKnownStatusId == null) {
      print('[OrderPolling] ⚠️ No order to poll, stopping');
      stopPolling();
      return;
    }

    try {
      print('[OrderPolling] 🔍 Checking status for OrderID=$_currentOrderId');

      final data = await Api.checkOrderStatus(
        orderId: _currentOrderId!,
        lastKnownStatusId: _lastKnownStatusId!,
      );

      if (data['OK'] == true && data['HAS_UPDATE'] == true) {
        final orderStatus = data['ORDER_STATUS'];
        final newStatusId = (orderStatus['StatusID'] as num).toInt();
        final statusName = orderStatus['StatusName'] as String;
        final message = orderStatus['Message'] as String;

        print('[OrderPolling] ✅ Status update detected: $statusName (ID=$newStatusId)');

        // Update last known status
        _lastKnownStatusId = newStatusId;

        // Notify listener
        if (_onStatusUpdate != null) {
          _onStatusUpdate!(OrderStatusUpdate(
            orderId: _currentOrderId!,
            statusId: newStatusId,
            statusName: statusName,
            message: message,
          ));
        }
      } else {
        print('[OrderPolling] ℹ️ No status update');
      }
    } catch (e) {
      print('[OrderPolling] ❌ Error checking status: $e');
    }
  }
}

/// Data class representing an order status update
class OrderStatusUpdate {
  final int orderId;
  final int statusId;
  final String statusName;
  final String message;

  const OrderStatusUpdate({
    required this.orderId,
    required this.statusId,
    required this.statusName,
    required this.message,
  });

  @override
  String toString() => 'OrderStatusUpdate(orderId: $orderId, statusId: $statusId, statusName: $statusName, message: $message)';
}