import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import '../app/app_state.dart';
import '../models/cart.dart';
import '../models/menu_item.dart';
import '../services/api.dart';
import '../services/order_polling_service.dart';

class CartViewScreen extends StatefulWidget {
  const CartViewScreen({super.key});

  @override
  State<CartViewScreen> createState() => _CartViewScreenState();
}

class _CartViewScreenState extends State<CartViewScreen> {
  Cart? _cart;
  bool _isLoading = true;
  String? _error;
  Map<int, MenuItem> _menuItemsById = {};

  @override
  void initState() {
    super.initState();
    _loadCart();
  }

  Future<void> _loadCart() async {
    setState(() {
      _isLoading = true;
      _error = null;
    });

    try {
      final appState = context.read<AppState>();
      final cartOrderId = appState.cartOrderId;

      if (cartOrderId == null) {
        setState(() {
          _isLoading = false;
          _cart = null;
        });
        return;
      }

      // Load cart
      final cart = await Api.getCart(orderId: cartOrderId);

      // Load menu items to get names and prices
      final businessId = appState.selectedBusinessId;
      if (businessId != null) {
        final menuItems = await Api.listMenuItems(businessId: businessId);
        _menuItemsById = {for (var item in menuItems) item.itemId: item};
      }

      setState(() {
        _cart = cart;
        _isLoading = false;
      });

      // Update item count in app state
      appState.updateCartItemCount(cart.itemCount);
    } catch (e) {
      setState(() {
        _error = e.toString();
        _isLoading = false;
      });
    }
  }

  Future<void> _removeLineItem(OrderLineItem lineItem) async {
    try {
      final appState = context.read<AppState>();
      final cartOrderId = appState.cartOrderId;
      if (cartOrderId == null) return;

      setState(() => _isLoading = true);

      // Set IsSelected=false to remove the item
      await Api.setLineItem(
        orderId: cartOrderId,
        parentOrderLineItemId: lineItem.parentOrderLineItemId,
        itemId: lineItem.itemId,
        isSelected: false,
      );

      // Reload cart
      await _loadCart();
    } catch (e) {
      setState(() {
        _error = e.toString();
        _isLoading = false;
      });
    }
  }

  Future<void> _updateQuantity(OrderLineItem lineItem, int newQuantity) async {
    if (newQuantity < 1) return;

    try {
      final appState = context.read<AppState>();
      final cartOrderId = appState.cartOrderId;
      if (cartOrderId == null) return;

      setState(() => _isLoading = true);

      await Api.setLineItem(
        orderId: cartOrderId,
        parentOrderLineItemId: lineItem.parentOrderLineItemId,
        itemId: lineItem.itemId,
        isSelected: true,
        quantity: newQuantity,
        remark: lineItem.remark,
      );

      // Reload cart
      await _loadCart();
    } catch (e) {
      setState(() {
        _error = e.toString();
        _isLoading = false;
      });
    }
  }

  Future<void> _submitOrder() async {
    try {
      final appState = context.read<AppState>();
      final cartOrderId = appState.cartOrderId;
      if (cartOrderId == null) return;

      setState(() => _isLoading = true);

      await Api.submitOrder(orderId: cartOrderId);

      // Set active order for polling (status 1 = submitted)
      appState.setActiveOrder(orderId: cartOrderId, statusId: 1);

      // Start polling for status updates
      OrderPollingService.startPolling(
        orderId: cartOrderId,
        initialStatusId: 1,
        onStatusUpdate: (update) {
          // Update app state
          appState.updateActiveOrderStatus(update.statusId);

          // Show notification
          if (mounted) {
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(
                content: Text(update.message),
                backgroundColor: _getStatusColor(update.statusId),
                duration: const Duration(seconds: 5),
                behavior: SnackBarBehavior.floating,
              ),
            );
          }
        },
      );

      // Clear cart state
      appState.clearCart();

      if (!mounted) return;

      // Show success message
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(
          content: Text("Order submitted successfully! You'll receive notifications as your order is prepared."),
          backgroundColor: Colors.green,
          duration: Duration(seconds: 5),
        ),
      );

      // Navigate back
      Navigator.of(context).pop();
    } catch (e) {
      setState(() {
        _error = e.toString();
        _isLoading = false;
      });
    }
  }

  Color _getStatusColor(int statusId) {
    switch (statusId) {
      case 1: // Submitted
        return Colors.blue;
      case 2: // Preparing
        return Colors.orange;
      case 3: // Ready
        return Colors.green;
      case 4: // Completed
        return Colors.purple;
      default:
        return Colors.grey;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Cart"),
        backgroundColor: Colors.black,
        foregroundColor: Colors.white,
      ),
      body: _isLoading
          ? const Center(child: CircularProgressIndicator())
          : _error != null
              ? Center(
                  child: Padding(
                    padding: const EdgeInsets.all(16),
                    child: Column(
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: [
                        const Icon(Icons.error, color: Colors.red, size: 48),
                        const SizedBox(height: 16),
                        Text(
                          "Error loading cart",
                          style: Theme.of(context).textTheme.titleLarge,
                        ),
                        const SizedBox(height: 8),
                        Text(_error!, textAlign: TextAlign.center),
                        const SizedBox(height: 16),
                        ElevatedButton(
                          onPressed: _loadCart,
                          child: const Text("Retry"),
                        ),
                      ],
                    ),
                  ),
                )
              : _cart == null || _cart!.itemCount == 0
                  ? Center(
                      child: Column(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: [
                          const Icon(
                            Icons.shopping_cart_outlined,
                            size: 80,
                            color: Colors.grey,
                          ),
                          const SizedBox(height: 16),
                          Text(
                            "Your cart is empty",
                            style: Theme.of(context).textTheme.titleLarge,
                          ),
                        ],
                      ),
                    )
                  : Column(
                      children: [
                        Expanded(
                          child: ListView(
                            padding: const EdgeInsets.all(16),
                            children: _buildCartItems(),
                          ),
                        ),
                        _buildCartSummary(),
                      ],
                    ),
    );
  }

  List<Widget> _buildCartItems() {
    if (_cart == null) return [];

    // Group line items by root items
    final rootItems = _cart!.lineItems
        .where((item) => item.parentOrderLineItemId == 0 && !item.isDeleted)
        .toList();

    final widgets = <Widget>[];

    for (final rootItem in rootItems) {
      widgets.add(_buildRootItemCard(rootItem));
      widgets.add(const SizedBox(height: 12));
    }

    return widgets;
  }

  Widget _buildRootItemCard(OrderLineItem rootItem) {
    final menuItem = _menuItemsById[rootItem.itemId];
    final itemName = menuItem?.name ?? "Item #${rootItem.itemId}";

    // Find all modifiers for this root item
    final modifiers = _cart!.lineItems
        .where((item) =>
            item.parentOrderLineItemId == rootItem.orderLineItemId &&
            !item.isDeleted)
        .toList();

    return Card(
      child: Padding(
        padding: const EdgeInsets.all(12),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Expanded(
                  child: Text(
                    itemName,
                    style: const TextStyle(
                      fontSize: 16,
                      fontWeight: FontWeight.bold,
                    ),
                  ),
                ),
                IconButton(
                  icon: const Icon(Icons.delete, color: Colors.red),
                  onPressed: () => _confirmRemoveItem(rootItem, itemName),
                ),
              ],
            ),
            if (modifiers.isNotEmpty) ...[
              const SizedBox(height: 8),
              ...modifiers.map((mod) => _buildModifierRow(mod)),
            ],
            const SizedBox(height: 8),
            Row(
              children: [
                IconButton(
                  icon: const Icon(Icons.remove_circle_outline),
                  onPressed: rootItem.quantity > 1
                      ? () => _updateQuantity(rootItem, rootItem.quantity - 1)
                      : null,
                ),
                Text(
                  "${rootItem.quantity}",
                  style: const TextStyle(
                    fontSize: 16,
                    fontWeight: FontWeight.bold,
                  ),
                ),
                IconButton(
                  icon: const Icon(Icons.add_circle_outline),
                  onPressed: () =>
                      _updateQuantity(rootItem, rootItem.quantity + 1),
                ),
                const Spacer(),
                Text(
                  "\$${rootItem.price.toStringAsFixed(2)}",
                  style: const TextStyle(
                    fontSize: 16,
                    fontWeight: FontWeight.bold,
                  ),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildModifierRow(OrderLineItem modifier) {
    final menuItem = _menuItemsById[modifier.itemId];
    final modName = menuItem?.name ?? "Modifier #${modifier.itemId}";

    return Padding(
      padding: const EdgeInsets.only(left: 16, top: 4),
      child: Row(
        children: [
          const Icon(Icons.add, size: 12, color: Colors.grey),
          const SizedBox(width: 4),
          Expanded(
            child: Text(
              modName,
              style: const TextStyle(
                fontSize: 14,
                color: Colors.grey,
              ),
            ),
          ),
          if (modifier.price > 0)
            Text(
              "+\$${modifier.price.toStringAsFixed(2)}",
              style: const TextStyle(
                fontSize: 14,
                color: Colors.grey,
              ),
            ),
        ],
      ),
    );
  }

  Widget _buildCartSummary() {
    if (_cart == null) return const SizedBox.shrink();

    return Container(
      decoration: BoxDecoration(
        color: Colors.grey[100],
        boxShadow: [
          BoxShadow(
            color: Colors.black.withOpacity(0.1),
            blurRadius: 4,
            offset: const Offset(0, -2),
          ),
        ],
      ),
      padding: const EdgeInsets.all(16),
      child: SafeArea(
        child: Column(
          children: [
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                const Text(
                  "Subtotal",
                  style: TextStyle(fontSize: 16),
                ),
                Text(
                  "\$${_cart!.subtotal.toStringAsFixed(2)}",
                  style: const TextStyle(fontSize: 16),
                ),
              ],
            ),
            if (_cart!.deliveryFee > 0) ...[
              const SizedBox(height: 8),
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: [
                  const Text(
                    "Delivery Fee",
                    style: TextStyle(fontSize: 16),
                  ),
                  Text(
                    "\$${_cart!.deliveryFee.toStringAsFixed(2)}",
                    style: const TextStyle(fontSize: 16),
                  ),
                ],
              ),
            ],
            const Divider(height: 24),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                const Text(
                  "Total",
                  style: TextStyle(
                    fontSize: 18,
                    fontWeight: FontWeight.bold,
                  ),
                ),
                Text(
                  "\$${_cart!.total.toStringAsFixed(2)}",
                  style: const TextStyle(
                    fontSize: 18,
                    fontWeight: FontWeight.bold,
                  ),
                ),
              ],
            ),
            const SizedBox(height: 16),
            SizedBox(
              width: double.infinity,
              child: ElevatedButton(
                onPressed: _cart!.itemCount > 0 ? _submitOrder : null,
                style: ElevatedButton.styleFrom(
                  backgroundColor: Colors.black,
                  foregroundColor: Colors.white,
                  padding: const EdgeInsets.symmetric(vertical: 16),
                ),
                child: const Text(
                  "Submit Order",
                  style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  void _confirmRemoveItem(OrderLineItem item, String itemName) {
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text("Remove Item"),
        content: Text("Remove $itemName from cart?"),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(context).pop(),
            child: const Text("Cancel"),
          ),
          TextButton(
            onPressed: () {
              Navigator.of(context).pop();
              _removeLineItem(item);
            },
            style: TextButton.styleFrom(foregroundColor: Colors.red),
            child: const Text("Remove"),
          ),
        ],
      ),
    );
  }
}