import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:cached_network_image/cached_network_image.dart';
import '../providers/cart_provider.dart';
import '../services/coupon_service.dart';
import '../models/coupon.dart';
import 'product_detail_screen.dart';
import 'checkout_screen.dart';

class _CartScreenState extends State<CartScreen> {
  final CouponService _couponService = CouponService();
  final TextEditingController _couponController = TextEditingController();
  Coupon? _appliedCoupon;
  bool _isValidatingCoupon = false;

  @override
  void dispose() {
    _couponController.dispose();
    super.dispose();
  }

  Future<void> _applyCoupon() async {
    if (_couponController.text.trim().isEmpty) return;

    setState(() {
      _isValidatingCoupon = true;
    });

    final coupon = await _couponService.validateCoupon(_couponController.text.trim());
    
    setState(() {
      _appliedCoupon = coupon.isValid ? coupon : null;
      _isValidatingCoupon = false;
    });

    if (!coupon.isValid) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(coupon.errorMessage ?? 'Ungültiger Gutschein-Code'),
            backgroundColor: Colors.red,
          ),
        );
      }
    }
  }

  void _removeCoupon() {
    setState(() {
      _appliedCoupon = null;
      _couponController.clear();
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Warenkorb'),
      ),
      body: Consumer<CartProvider>(
        builder: (context, cart, child) {
          if (cart.items.isEmpty) {
            return Center(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Icon(
                    Icons.shopping_cart_outlined,
                    size: 64,
                    color: Colors.grey[400],
                  ),
                  const SizedBox(height: 16),
                  Text(
                    'Dein Warenkorb ist leer',
                    style: Theme.of(context).textTheme.titleLarge?.copyWith(
                          color: Colors.grey[600],
                        ),
                  ),
                  const SizedBox(height: 8),
                  Text(
                    'Füge Produkte hinzu, um zu beginnen',
                    style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                          color: Colors.grey[500],
                        ),
                  ),
                ],
              ),
            );
          }

          return Column(
            children: [
              Expanded(
                child: ListView.builder(
                  padding: const EdgeInsets.all(16),
                  itemCount: cart.items.length,
                  itemBuilder: (context, index) {
                    final item = cart.items[index];
                    return Card(
                      margin: const EdgeInsets.only(bottom: 12),
                      child: InkWell(
                        onTap: () {
                          Navigator.push(
                            context,
                            MaterialPageRoute(
                              builder: (context) => ProductDetailScreen(
                                product: item.product,
                              ),
                            ),
                          );
                        },
                        child: Padding(
                          padding: const EdgeInsets.all(12),
                          child: Row(
                            children: [
                              // Produktbild
                              if (item.product.imageUrl != null)
                                ClipRRect(
                                  borderRadius: BorderRadius.circular(8),
                                  child: CachedNetworkImage(
                                    imageUrl: item.product.imageUrl!,
                                    width: 80,
                                    height: 80,
                                    fit: BoxFit.cover,
                                    placeholder: (context, url) => Container(
                                      width: 80,
                                      height: 80,
                                      color: Colors.grey[300],
                                      child: const Center(
                                        child: CircularProgressIndicator(),
                                      ),
                                    ),
                                    errorWidget: (context, url, error) =>
                                        Container(
                                      width: 80,
                                      height: 80,
                                      color: Colors.grey[300],
                                      child: const Icon(Icons.image_not_supported),
                                    ),
                                  ),
                                )
                              else
                                Container(
                                  width: 80,
                                  height: 80,
                                  color: Colors.grey[300],
                                  child: const Icon(Icons.image_not_supported),
                                ),
                              const SizedBox(width: 12),
                              
                              // Produktinfo
                              Expanded(
                                child: Column(
                                  crossAxisAlignment: CrossAxisAlignment.start,
                                  children: [
                                    Text(
                                      item.product.name,
                                      style: Theme.of(context)
                                          .textTheme
                                          .titleMedium
                                          ?.copyWith(
                                            fontWeight: FontWeight.bold,
                                          ),
                                      maxLines: 2,
                                      overflow: TextOverflow.ellipsis,
                                    ),
                                    const SizedBox(height: 4),
                                    Text(
                                      '${item.product.price} €',
                                      style: Theme.of(context)
                                          .textTheme
                                          .bodyLarge
                                          ?.copyWith(
                                            color: const Color(0xFF8B6F47),
                                            fontWeight: FontWeight.bold,
                                          ),
                                    ),
                                  ],
                                ),
                              ),
                              
                              // Mengensteuerung
                              Column(
                                children: [
                                  Row(
                                    mainAxisSize: MainAxisSize.min,
                                    children: [
                                      IconButton(
                                        icon: const Icon(Icons.remove_circle_outline),
                                        onPressed: () => cart.removeItem(item.product),
                                      ),
                                      Text(
                                        '${item.quantity}',
                                        style: Theme.of(context).textTheme.titleMedium,
                                      ),
                                      IconButton(
                                        icon: const Icon(Icons.add_circle_outline),
                                        onPressed: () => cart.addItem(item.product),
                                      ),
                                    ],
                                  ),
                                  Text(
                                    '${item.totalPrice.toStringAsFixed(2)} €',
                                    style: Theme.of(context)
                                        .textTheme
                                        .bodyMedium
                                        ?.copyWith(
                                          fontWeight: FontWeight.bold,
                                        ),
                                  ),
                                ],
                              ),
                              
                              // Entfernen
                              IconButton(
                                icon: const Icon(Icons.delete_outline),
                                color: Colors.red,
                                onPressed: () {
                                  cart.removeItemCompletely(item.product);
                                  ScaffoldMessenger.of(context).showSnackBar(
                                    SnackBar(
                                      content: Text('${item.product.name} entfernt'),
                                    ),
                                  );
                                },
                              ),
                            ],
                          ),
                        ),
                      ),
                    );
                  },
                ),
              ),
              
              // Gesamtsumme und Checkout
              Container(
                padding: const EdgeInsets.all(16),
                decoration: BoxDecoration(
                  color: Colors.white,
                  boxShadow: [
                    BoxShadow(
                      color: Colors.black.withOpacity(0.1),
                      blurRadius: 4,
                      offset: const Offset(0, -2),
                    ),
                  ],
                ),
                child: Column(
                  children: [
                    // Gutschein-Eingabe
                    Container(
                      padding: const EdgeInsets.all(12),
                      decoration: BoxDecoration(
                        color: Colors.grey[100],
                        borderRadius: BorderRadius.circular(8),
                      ),
                      child: Row(
                        children: [
                          Expanded(
                            child: TextField(
                              controller: _couponController,
                              decoration: InputDecoration(
                                hintText: 'Gutschein-Code',
                                border: InputBorder.none,
                                isDense: true,
                              ),
                              enabled: !_isValidatingCoupon && _appliedCoupon == null,
                            ),
                          ),
                          if (_appliedCoupon != null)
                            IconButton(
                              icon: const Icon(Icons.check_circle, color: Colors.green),
                              onPressed: _removeCoupon,
                            )
                          else
                            IconButton(
                              icon: _isValidatingCoupon
                                  ? const SizedBox(
                                      width: 20,
                                      height: 20,
                                      child: CircularProgressIndicator(strokeWidth: 2),
                                    )
                                  : const Icon(Icons.add),
                              onPressed: _isValidatingCoupon ? null : _applyCoupon,
                            ),
                        ],
                      ),
                    ),
                    if (_appliedCoupon != null) ...[
                      const SizedBox(height: 8),
                      Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        children: [
                          Text(
                            'Rabatt (${_appliedCoupon!.code}):',
                            style: Theme.of(context).textTheme.bodyMedium,
                          ),
                          Text(
                            '-${_couponService.calculateDiscount(_appliedCoupon!, cart.totalPrice).toStringAsFixed(2)} €',
                            style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                                  color: Colors.green,
                                  fontWeight: FontWeight.bold,
                                ),
                          ),
                        ],
                      ),
                    ],
                    const SizedBox(height: 12),
                    Row(
                      mainAxisAlignment: MainAxisAlignment.spaceBetween,
                      children: [
                        Text(
                          'Gesamtsumme:',
                          style: Theme.of(context).textTheme.titleLarge?.copyWith(
                                fontWeight: FontWeight.bold,
                              ),
                        ),
                        Text(
                          '${(cart.totalPrice - (_appliedCoupon != null ? _couponService.calculateDiscount(_appliedCoupon!, cart.totalPrice) : 0)).toStringAsFixed(2)} €',
                          style: Theme.of(context).textTheme.headlineSmall?.copyWith(
                                color: const Color(0xFF8B6F47),
                                fontWeight: FontWeight.bold,
                              ),
                        ),
                      ],
                    ),
                    const SizedBox(height: 16),
                    SizedBox(
                      width: double.infinity,
                      child: ElevatedButton(
                        onPressed: () {
                          Navigator.push(
                            context,
                            MaterialPageRoute(
                              builder: (context) => const CheckoutScreen(),
                            ),
                          );
                        },
                        style: ElevatedButton.styleFrom(
                          backgroundColor: const Color(0xFF8B6F47),
                          foregroundColor: Colors.white,
                          padding: const EdgeInsets.symmetric(vertical: 16),
                          shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(8),
                          ),
                        ),
                        child: const Text(
                          'Zur Kasse',
                          style: TextStyle(fontSize: 16),
                        ),
                      ),
                    ),
                  ],
                ),
              ),
            ],
          );
        },
      ),
    );
  }
}

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

  @override
  State<CartScreen> createState() => _CartScreenState();
}