// Version: 1.10 - 売上入力画面（簡易実装）
import 'package:flutter/material.dart';
import '../services/database_helper.dart';
import '../models/product.dart';
import '../models/customer.dart';

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

  @override
  State<SalesScreen> createState() => _SalesScreenState();
}

class _SalesScreenState extends State<SalesScreen> with WidgetsBindingObserver {
  List<Product> products = <Product>[];
  List<_SaleItem> saleItems = <_SaleItem>[];
  double totalAmount = 0.0;
  Customer? selectedCustomer;

  Future<void> loadProducts() async {
    try {
      final ps = await DatabaseHelper.instance.getProducts();
      if (mounted) setState(() => products = ps ?? const <Product>[]);
    } catch (e) {}
  }

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => loadProducts());
  }

  Future<void> searchProduct(String keyword) async {
    if (!mounted || keyword.isEmpty) return;
    
    final keywordLower = keyword.toLowerCase();
    final matchedProducts = products.where((p) =>
        (p.name?.toLowerCase() ?? '').contains(keywordLower) ||
        (p.productCode ?? '').contains(keyword)).toList();

    setState(() {
      for (final product in matchedProducts) {
        final existingItemIndex = saleItems.indexWhere((item) => item.productId == product.id);
        if (existingItemIndex == -1 || saleItems[existingItemIndex].quantity < 1) {
          saleItems.add(_SaleItem(
            productId: product.id ?? 0,
            productName: product.name ?? '',
            productCode: product.productCode ?? '',
            unitPrice: product.unitPrice ?? 0.0,
            quantity: 1,
            totalAmount: (product.unitPrice ?? 0.0),
          ));
        } else {
          saleItems[existingItemIndex].quantity += 1;
          saleItems[existingItemIndex].totalAmount = 
              saleItems[existingItemIndex].unitPrice * saleItems[existingItemIndex].quantity;
        }
      }
      calculateTotal();
    });
  }

  void removeItem(int index) {
    if (index >= 0 && index < saleItems.length) {
      saleItems.removeAt(index);
      calculateTotal();
    }
  }

  void calculateTotal() {
    final items = saleItems.map((item) => item.totalAmount).toList();
    setState(() => totalAmount = items.fold(0, (sum, val) => sum + val));
  }

  Future<void> saveSale() async {
    if (saleItems.isEmpty || !mounted) return;

    try {
      showDialog(
        context: context,
        builder: (context) => AlertDialog(
          title: const Text('売上データ保存'),
          content: Text('入力した商品情報を販売アシストに保存します。'),
          actions: [
            TextButton(onPressed: () => Navigator.pop(context), child: const Text('キャンセル')),
            ElevatedButton(
              onPressed: () async {
                await DatabaseHelper.instance.insertSales({
                  'id': DateTime.now().millisecondsSinceEpoch,
                  'customer_id': selectedCustomer?.id ?? 1,
                  'sale_date': DateTime.now().toIso8601String(),
                  'total_amount': (totalAmount * 1.1).round(),
                  'tax_rate': 8,
                });

                if (mounted) ScaffoldMessenger.of(context).showSnackBar(
                  const SnackBar(content: Text('売上データ保存完了'), duration: Duration(seconds: 2)),
                );
              },
              child: const Text('保存'),
            ),
          ],
        ),
      );
    } catch (e) {
      WidgetsBinding.instance.addPostFrameCallback((_) => ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('保存エラー：$e'), backgroundColor: Colors.red),
      ));
    }
  }

  void showInvoiceDialog() {
    if (saleItems.isEmpty || !mounted) return;

    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('売上伝票'),
        content: Padding(
          padding: const EdgeInsets.all(16),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text('得意先：${selectedCustomer?.name ?? '未指定'}', style: Theme.of(context).textTheme.titleMedium),
              const SizedBox(height: 8),
              Text('商品数：${saleItems.length}'),
              const SizedBox(height: 4),
              Text('合計：¥${totalAmount.toStringAsFixed(0)}', style: const TextStyle(fontWeight: FontWeight.bold, color: Colors.teal)),
            ],
          ),
        ),
        actions: [
          TextButton(onPressed: () => Navigator.pop(context), child: const Text('キャンセル')),
          ElevatedButton(child: const Text('閉じる'), onPressed: () => Navigator.pop(context),),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('売上入力'), actions: [
        IconButton(icon: const Icon(Icons.save), onPressed: saveSale,),
        IconButton(icon: const Icon(Icons.print, color: Colors.blue), onPressed: () => showInvoiceDialog(),),
      ]),
      body: Column(
        children: <Widget>[
          Padding(
            padding: const EdgeInsets.all(16),
            child: Card(
              elevation: 4,
              child: Padding(
                padding: const EdgeInsets.all(16),
                child: Column(crossAxisAlignment: CrossAxisAlignment.stretch, children: [
                  Text('レジモード', style: Theme.of(context).textTheme.titleLarge?.copyWith(fontWeight: FontWeight.bold)),
                  const SizedBox(height: 8),
                  Row(children: <Widget>[Text('合計'), const Icon(Icons.payments, size: 32)]),
                  const SizedBox(height: 4),
                  Text('¥${totalAmount.toStringAsFixed(0)}', style: const TextStyle(fontSize: 48, fontWeight: FontWeight.bold, color: Colors.teal)),
                ],),
              ),
            ),
          ),
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 16),
            child: TextField(
              decoration: InputDecoration(labelText: '商品検索', hintText: 'JAN コードまたは商品名を入力して選択', prefixIcon: const Icon(Icons.search)),
              onChanged: searchProduct,
            ),
          ),
          Expanded(
            child: saleItems.isEmpty 
                ? const Center(child: Text('商品を登録')) 
                : ListView.separated(
                    itemCount: saleItems.length,
                    itemBuilder: (context, index) {
                      final item = saleItems[index];
                      return Padding(
                        padding: const EdgeInsets.symmetric(vertical: 4),
                        child: Card(
                          child: ListTile(
                            leading: CircleAvatar(child: Icon(Icons.store)),
                            title: Text(item.productName ?? ''),
                            subtitle: Text('コード：${item.productCode} / ¥${item.totalAmount.toStringAsFixed(0)}'),
                            trailing: IconButton(icon: const Icon(Icons.remove_circle_outline), onPressed: () => removeItem(index),),
                          ),
                        ),
                      );
                    },
                    separatorBuilder: (_, __) => const Divider(),
                  ),
          ),
        ],
      ),
    );
  }
}

class _SaleItem {
  final int productId;
  final String productName;
  final String productCode;
  final double unitPrice;
  int quantity;
  double totalAmount;

  _SaleItem({
    required this.productId,
    required this.productName,
    required this.productCode,
    required this.unitPrice,
    required this.quantity,
    required this.totalAmount,
  });
}