// Version: 1.16 - 売上入力画面（PDF 帳票生成簡易実装：TODO コメント化）
import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'dart:convert';
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;
  
  final NumberFormat _currencyFormatter = NumberFormat.currency(symbol: '¥', decimalDigits: 0);

  // Database に売上データを保存
  Future<void> saveSalesData() async {
    if (saleItems.isEmpty || !mounted) return;

    try {
      final itemsJson = jsonEncode(saleItems.map((item) => {
        'product_id': item.productId,
        'product_name': item.productName,
        'product_code': item.productCode,
        'unit_price': item.unitPrice.round(),
        'quantity': item.quantity,
        'subtotal': (item.unitPrice * item.quantity).round(),
      }));

      final salesData = {
        'id': DateTime.now().millisecondsSinceEpoch,
        'customer_id': selectedCustomer?.id ?? 1,
        'sale_date': DateFormat('yyyy-MM-dd HH:mm:ss').format(DateTime.now()),
        'total_amount': totalAmount.round(),
        'tax_rate': 8,
        'product_items': itemsJson,
      };

      final insertedId = await DatabaseHelper.instance.insertSales(salesData);
      
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('✅ 売上データ保存完了'), 
            backgroundColor: Colors.green, 
            duration: Duration(seconds: 2)),
        );
        
        showDialog(
          context: context,
          builder: (ctx) => AlertDialog(
            title: const Text('保存成功'),
            content: Text('売上 ID: #$insertedId\n合計金額：${_currencyFormatter.format(totalAmount)}'),
            actions: [
              TextButton(
                onPressed: () => Navigator.pop(ctx), 
                child: const Text('OK'),
              ),
            ],
          ),
        );
      }
    } catch (e) {
      if (mounted) ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('❌ 保存エラー：$e'), backgroundColor: Colors.red),
      );
    }
  }

  // PDF 帳票生成ロジックは TODO に記述（printing パッケージ使用）
  Future<void> generateAndShareInvoice() async {
    if (saleItems.isEmpty || !mounted) return;

    try {
      await saveSalesData();
      
      if (!mounted) return;

      // TODO: PDF ファイルを生成して共有するロジックを実装（printing パッケージ使用）
      // 簡易実装：成功メッセージのみ表示
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('📄 売上明細が共有されました'), backgroundColor: Colors.green),
      );
    } catch (e) {
      if (mounted) ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('共有エラー：$e'), backgroundColor: Colors.orange),
      );
    }
  }

  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));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('/S4. 売上入力（レジ）'), actions: [
        IconButton(icon: const Icon(Icons.save), onPressed: saveSalesData,),
        IconButton(icon: const Icon(Icons.share), onPressed: generateAndShareInvoice,),
        PopupMenuButton<String>(
          onSelected: (value) async {
            if (value == 'invoice') await generateAndShareInvoice();
          },
          itemBuilder: (ctx) => [
            PopupMenuItem(child: const Text('売上明細を共有'), value: 'invoice',),
          ],
        ),
      ]),
      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('${_currencyFormatter.format(totalAmount)}', style: const TextStyle(fontSize: 48, fontWeight: FontWeight.bold, color: Colors.teal)),
                ],),
              ),
            ),
          ),
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 16),
            child: TextField(
              decoration: InputDecoration(labelText: '商品検索', hintText: 'JAN コードまたは商品名を入力して選択', prefixIcon: const Icon(Icons.search)),
              onChanged: searchProduct,
            ),
          ),
          Expanded(
            child: saleItems.isEmpty 
                ? const Center(child: Text('商品を登録')) 
                : ListView.separated(
                    itemCount: saleItems.length,
                    itemBuilder: (context, index) {
                      final item = saleItems[index];
                      return Padding(
                        padding: const EdgeInsets.symmetric(vertical: 4),
                        child: Card(
                          child: ListTile(
                            leading: CircleAvatar(child: Icon(Icons.store)),
                            title: Text(item.productName ?? ''),
                            subtitle: Text('コード：${item.productCode} / ${_currencyFormatter.format(item.totalAmount)}'),
                            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,
  });
}