import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../providers/cart_provider.dart';
import '../models/product.dart';
import '../services/woocommerce_service.dart';
import '../widgets/product_card.dart';
import 'product_detail_screen.dart';

class ProductsScreen extends StatefulWidget {
  final String? categoryId;
  final String? categoryName;

  const ProductsScreen({
    super.key,
    this.categoryId,
    this.categoryName,
  });

  @override
  State<ProductsScreen> createState() => _ProductsScreenState();
}

class _ProductsScreenState extends State<ProductsScreen> {
  final WooCommerceService _wooCommerceService = WooCommerceService();
  List<Product> _products = [];
  bool _isLoading = true;
  bool _isLoadingMore = false;
  String? _error;
  int _currentPage = 1;
  final int _perPage = 20;
  bool _hasMore = true;
  final ScrollController _scrollController = ScrollController();

  @override
  void initState() {
    super.initState();
    _loadProducts();
    _scrollController.addListener(_onScroll);
  }

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

  void _onScroll() {
    if (_scrollController.position.pixels >=
        _scrollController.position.maxScrollExtent * 0.9) {
      if (!_isLoadingMore && _hasMore) {
        _loadMoreProducts();
      }
    }
  }

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

      final products = await _wooCommerceService.getProducts(
        perPage: _perPage,
        page: 1,
        category: widget.categoryId,
      );

      setState(() {
        _products = products;
        _isLoading = false;
        _currentPage = 1;
        _hasMore = products.length == _perPage;
      });
    } catch (e) {
      setState(() {
        _error = e.toString();
        _isLoading = false;
      });
    }
  }

  Future<void> _loadMoreProducts() async {
    if (_isLoadingMore || !_hasMore) return;

    try {
      setState(() {
        _isLoadingMore = true;
      });

      final nextPage = _currentPage + 1;
      final products = await _wooCommerceService.getProducts(
        perPage: _perPage,
        page: nextPage,
      );

      setState(() {
        if (products.isEmpty) {
          _hasMore = false;
        } else {
          _products.addAll(products);
          _currentPage = nextPage;
          _hasMore = products.length == _perPage;
        }
        _isLoadingMore = false;
      });
    } catch (e) {
      setState(() {
        _isLoadingMore = false;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.categoryName ?? 'Alle Produkte'),
      ),
      body: _buildBody(),
    );
  }

  Widget _buildBody() {
    if (_isLoading) {
      return const Center(child: CircularProgressIndicator());
    }

    if (_error != null) {
      return Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Icon(Icons.error_outline, size: 64, color: Colors.red),
            const SizedBox(height: 16),
            Text(
              'Fehler beim Laden der Produkte',
              style: Theme.of(context).textTheme.titleLarge,
            ),
            const SizedBox(height: 8),
            Padding(
              padding: const EdgeInsets.symmetric(horizontal: 32),
              child: Text(
                _error!,
                style: Theme.of(context).textTheme.bodyMedium,
                textAlign: TextAlign.center,
              ),
            ),
            const SizedBox(height: 16),
            ElevatedButton(
              onPressed: _loadProducts,
              child: const Text('Erneut versuchen'),
            ),
          ],
        ),
      );
    }

    if (_products.isEmpty) {
      return const Center(
        child: Text('Keine Produkte verfügbar'),
      );
    }

    return RefreshIndicator(
      onRefresh: _loadProducts,
      child: GridView.builder(
        controller: _scrollController,
        padding: const EdgeInsets.all(16),
        gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 2,
          crossAxisSpacing: 16,
          mainAxisSpacing: 16,
          childAspectRatio: 0.75,
        ),
        itemCount: _products.length + (_isLoadingMore ? 1 : 0),
        itemBuilder: (context, index) {
          if (index == _products.length) {
            return const Center(child: CircularProgressIndicator());
          }

          return ProductCard(
            product: _products[index],
            onTap: () {
              Navigator.push(
                context,
                MaterialPageRoute(
                  builder: (context) => ProductDetailScreen(
                    product: _products[index],
                  ),
                ),
              );
            },
          );
        },
      ),
    );
  }
}