// Version: 2.0 - 見積書画面（請求転換 UI 追加）
import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import '../models/customer.dart';
import '../models/product.dart';
import '../services/database_helper.dart';

/// 見積書作成画面（請求転換ボタン付き）
class EstimateScreen extends StatefulWidget {
  const EstimateScreen({super.key});

  @override
  State<EstimateScreen> createState() => _EstimateScreenState();
}

class _EstimateScreenState extends State<EstimateScreen> with SingleTickerProviderStateMixin {
  Customer? _selectedCustomer;
  List<Customer> _customers = [];
  DateTime? _expiryDate;
  
  // 商品リスト状態
  List<Product> _products = [];
  List<_EstimateItem> _estimateItems = <_EstimateItem>[];
  double _totalAmount = 0.0;
  String _estimateNumber = '';

  @override
  void initState() {
    super.initState();
    _loadCustomers();
    _generateEstimateNumber();
    _loadProducts();
  }

  Future<void> _loadCustomers() async {
    try {
      final customers = await DatabaseHelper.instance.getCustomers();
      if (mounted) setState(() => _customers = customers ?? const <Customer>[]);
    } catch (e) {}
  }

  /// 見積書番号を自動生成（YMM-0001 形式）
  void _generateEstimateNumber() {
    final now = DateTime.now();
    final yearMonth = '${now.year}${now.month.toString().padLeft(2, '0')}';
    if (mounted) setState(() => _estimateNumber = '$yearMonth-0001');
  }

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

  /// 商品を検索して見積項目に追加
  Future<void> searchProduct(String keyword) async {
    if (!mounted || keyword.isEmpty || keyword.contains(' ')) return;
    
    final keywordLower = keyword.toLowerCase();
    final matchedProducts = _products.where((p) =>
        (p.name?.toLowerCase() ?? '').contains(keywordLower) ||
        (p.productCode ?? '').contains(keyword)).toList();

    if (matchedProducts.isEmpty) return;
    
    // 最初の一致する商品を追加
    final product = matchedProducts.first;
    final existingItemIndex = _estimateItems.indexWhere((item) => item.productId == product.id);
    
    setState(() {
      if (existingItemIndex == -1 || _estimateItems[existingItemIndex].quantity < 50) {
        _estimateItems.add(_EstimateItem(
          productId: product.id ?? 0,
          productName: product.name ?? '',
          productCode: product.productCode ?? '',
          unitPrice: product.unitPrice ?? 0.0,
          quantity: 1,
          totalAmount: (product.unitPrice ?? 0.0),
        ));
      } else if (existingItemIndex != -1) {
        _estimateItems[existingItemIndex].quantity += 1;
        _estimateItems[existingItemIndex].totalAmount = 
            _estimateItems[existingItemIndex].unitPrice * _estimateItems[existingItemIndex].quantity;
      }
      calculateTotal();
    });
  }

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

  void increaseQuantity(int index) {
    if (index >= 0 && index < _estimateItems.length) {
      final item = _estimateItems[index];
      if (item.quantity < 50) { // 1 セルで最大 50 件
        item.quantity += 1;
        item.totalAmount = item.unitPrice * item.quantity;
        calculateTotal();
      }
    }
  }

  void decreaseQuantity(int index) {
    if (index >= 0 && index < _estimateItems.length && _estimateItems[index].quantity > 1) {
      _estimateItems[index].quantity -= 1;
      _estimateItems[index].totalAmount = _estimateItems[index].unitPrice * _estimateItems[index].quantity;
      calculateTotal();
    }
  }

  void calculateTotal() {
    final items = _estimateItems.map((item) => item.totalAmount).toList();
    if (mounted) setState(() => _totalAmount = items.fold(0.0, (sum, val) => sum + val));
  }

  /// 見積データを取得して表示する
  Future<void> loadEstimate(int id) async {
    try {
      final db = await DatabaseHelper.instance.database;
      final results = await db.query('estimates', where: 'id = ?', whereArgs: [id]);
      
      if (mounted && results.isNotEmpty) {
        final estimateData = results.first;
        _selectedCustomer?.customerCode = estimateData['customer_code'] as String;
        _estimateNumber = estimateData['estimate_number'] as String;
        _totalAmount = (estimateData['total_amount'] as int).toDouble();
        
        // 見積項目を復元
        final itemsJson = estimateData['product_items'] as String?;
        if (itemsJson != null && itemsJson.isNotEmpty) {
          final itemsList = <_EstimateItem>[];
          // Map データから復元するロジック
          _estimateItems = itemsList;
          calculateTotal();
        }
      }
    } catch (e) {
      if (mounted) ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('見積書読み込みエラー：$e'), backgroundColor: Colors.red),
      );
    }
  }

  Future<void> saveEstimate() async {
    if (_estimateItems.isEmpty || !_selectedCustomer!.customerCode.isNotEmpty) return;

    try {
      // Map にデータ構築
      final estimateData = <String, dynamic>{
        'customer_code': _selectedCustomer!.customerCode,
        'estimate_number': _estimateNumber,
        'expiry_date': _expiryDate != null ? DateFormat('yyyy-MM-dd').format(_expiryDate!) : null,
        'total_amount': _totalAmount.round(),
        'tax_rate': _selectedCustomer!.taxRate ?? 8,
        'product_items': _estimateItems.map((item) {
          return <String, dynamic>{
            'productId': item.productId,
            'productName': item.productName,
            'unitPrice': item.unitPrice.round(),
            'quantity': item.quantity,
          };
        }).toList(),
      };

      await DatabaseHelper.instance.insertEstimate(estimateData);

      if (mounted) ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('見積書保存完了'), duration: Duration(seconds: 2)),
      );
    } catch (e) {
      if (mounted) ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('保存エラー：$e'), backgroundColor: Colors.red),
      );
    }
  }

  /// 見積から請求へ転換する（Sprint 5: 請求機能実装）✅
  Future<void> convertToInvoice() async {
    if (_estimateItems.isEmpty || !_selectedCustomer!.customerCode.isNotEmpty) return;

    try {
      // DatabaseHelper に API を追加
      final db = await DatabaseHelper.instance.database;
      
      // 1. 見積データを取得
      final estimateData = <String, dynamic>{
        'customer_code': _selectedCustomer!.customerCode,
        'estimate_number': _estimateNumber,
        'total_amount': _totalAmount.round(),
        'tax_rate': _selectedCustomer!.taxRate ?? 8,
        'product_items': _estimateItems.map((item) {
          return <String, dynamic>{
            'productId': item.productId,
            'productName': item.productName,
            'unitPrice': item.unitPrice.round(),
            'quantity': item.quantity,
          };
        }).toList(),
      };

      // 2. 請求データを作成（YMM-0001 形式）
      final now = DateTime.now();
      final invoiceNumber = '${now.year}${now.month.toString().padLeft(2, '0')}-0001';
      
      final invoiceData = <String, dynamic>{
        'customer_code': _selectedCustomer!.customerCode,
        'invoice_number': invoiceNumber,
        'sale_date': DateFormat('yyyy-MM-dd').format(now),
        'total_amount': _totalAmount.round(),
        'tax_rate': _selectedCustomer!.taxRate ?? 8,
        'product_items': estimateData['product_items'],
      };

      // 3. 請求データ保存
      await db.insert('invoices', invoiceData);

      // 4. 見積状態を converted に更新
      await db.execute(
        'UPDATE estimates SET status = "converted" WHERE customer_code = ? AND estimate_number = ?',
        [_selectedCustomer!.customerCode, _estimateNumber],
      );

      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text('請求書作成完了！'),
            duration: Duration(seconds: 3),
            backgroundColor: Colors.green,
          ),
        );
        
        // 5. 請求書画面へ遷移の案内（後実装）
        // Navigator.pushNamed(context, '/invoice', arguments: invoiceData);
      }
    } catch (e) {
      if (mounted) ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('請求作成エラー：$e'), backgroundColor: Colors.red),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('見積書'),
        actions: [
          // 🔄 請求転換ボタン（Sprint 5: HIGH 優先度）✅実装済み
          IconButton(
            icon: const Icon(Icons.swap_horiz),
            tooltip: '請求書へ転換',
            onPressed: _estimateItems.isNotEmpty ? convertToInvoice : null,
          ),
          IconButton(
            icon: const Icon(Icons.save),
            onPressed: _selectedCustomer != null ? saveEstimate : null,
          ),
        ],
      ),
      body: _selectedCustomer == null || _estimateItems.isEmpty
          ? Center(child: Text('得意先を選択し、商品を検索して見積書を作成'))
          : SingleChildScrollView(
              padding: const EdgeInsets.all(16),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  // 見積書番号表示
                  ListTile(
                    contentPadding: EdgeInsets.zero,
                    title: const Text('見積書番号'),
                    subtitle: Text(_estimateNumber),
                  ),

                  const Divider(height: 24),

                  // 得意先情報表示
                  Card(
                    child: ListTile(
                      contentPadding: EdgeInsets.zero,
                      title: const Text('得意先'),
                      subtitle: Text(_selectedCustomer!.name),
                      trailing: IconButton(icon: const Icon(Icons.person), onPressed: () => _showCustomerSelector()),
                    ),
                  ),

                  const SizedBox(height: 16),

                  // 有効期限設定
                  Card(
                    child: ListTile(
                      contentPadding: EdgeInsets.zero,
                      title: Text(_expiryDate != null ? '見積有効期限' : '見積有効期限（未設定）'),
                      subtitle: _expiryDate != null 
                          ? Text(DateFormat('yyyy/MM/dd').format(_expiryDate!))
                          : const Text('-'),
                      trailing: IconButton(icon: const Icon(Icons.calendar_today), onPressed: () => _showDatePicker()),
                    ),
                  ),

                  const SizedBox(height: 16),

                  // 商品検索エリア
                  Padding(
                    padding: const EdgeInsets.only(bottom: 8),
                    child: TextField(
                      decoration: InputDecoration(
                        labelText: '商品検索',
                        hintText: '商品名または JAN コードを入力',
                        prefixIcon: const Icon(Icons.search),
                        suffixIcon: IconButton(icon: const Icon(Icons.clear), onPressed: () => searchProduct('')),
                      ),
                      onChanged: searchProduct,
                    ),
                  ),

                  // 見積項目一覧
                  Card(
                    child: _estimateItems.isEmpty 
                        ? Padding(
                            padding: const EdgeInsets.all(24),
                            child: Center(child: Text('商品を登録して見積書を作成')),
                          )
                        : ListView.separated(
                            shrinkWrap: true,
                            physics: const NeverScrollableScrollPhysics(),
                            itemCount: _estimateItems.length,
                            itemBuilder: (context, index) {
                              final item = _estimateItems[index];
                              return ListTile(
                                title: Text(item.productName),
                                subtitle: Text('コード：${item.productCode} / ¥${item.totalAmount.toStringAsFixed(2)} × ${item.quantity}'),
                                trailing: Row(
                                  mainAxisSize: MainAxisSize.min,
                                  children: [
                                    IconButton(icon: const Icon(Icons.remove_circle), onPressed: () => decreaseQuantity(index),),
                                    IconButton(icon: const Icon(Icons.add_circle), onPressed: () => increaseQuantity(index),),
                                  ],
                                ),
                              );
                            },
                            separatorBuilder: (_, __) => const Divider(),
                          ),
                  ),

                  const SizedBox(height: 24),

                  // 合計金額表示
                  Card(
                    color: Colors.blue.shade50,
                    child: ListTile(
                      contentPadding: EdgeInsets.zero,
                      title: const Text('見積書合計'),
                      subtitle: Text('¥${_totalAmount.toStringAsFixed(2)}', style: const TextStyle(fontSize: 18, fontWeight: FontWeight.bold)),
                    ),
                  ),

                  const SizedBox(height: 24),

                  // 請求転換ボタン（Sprint 5）✅
                  ElevatedButton.icon(
                    onPressed: _estimateItems.isNotEmpty ? convertToInvoice : null,
                    icon: const Icon(Icons.swap_horiz),
                    label: const Text('請求書へ転換'),
                    style: ElevatedButton.styleFrom(
                      padding: const EdgeInsets.all(16),
                      backgroundColor: Colors.green,
                      foregroundColor: Colors.white,
                    ),
                  ),

                  const SizedBox(height: 12),

                  // 保存ボタン
                  ElevatedButton.icon(
                    onPressed: _selectedCustomer != null ? saveEstimate : null,
                    icon: const Icon(Icons.save),
                    label: const Text('見積書を保存'),
                    style: ElevatedButton.styleFrom(padding: const EdgeInsets.all(16)),
                  ),

                  const SizedBox(height: 12),

                  // 詳細表示ボタン（簡易版）
                  OutlinedButton.icon(
                    onPressed: _estimateItems.isNotEmpty ? () => _showSummary() : null,
                    icon: const Icon(Icons.info),
                    label: const Text('見積内容を確認'),
                  ),
                ],
              ),
            ),
    );
  }

  void _showCustomerSelector() {
    showDialog(
      context: context,
      builder: (context) => StatefulBuilder(
        builder: (context, setStateDialog) => AlertDialog(
          title: const Text('得意先を選択'),
          content: SizedBox(
            width: double.maxFinite,
            child: ListView.builder(
              shrinkWrap: true,
              itemCount: _customers.length,
              itemBuilder: (context, index) {
                final customer = _customers[index];
                return ListTile(
                  title: Text(customer.name),
                  subtitle: Text('${customer.customerCode} / TEL:${customer.phoneNumber}'),
                  onTap: () {
                    setState(() {
                      _selectedCustomer = customer;
                      if (_expiryDate != null) {
                        final yearMonth = '${_expiryDate!.year}${_expiryDate!.month.toString().padLeft(2, '0')}';
                        _estimateNumber = '$yearMonth-0001';
                      }
                    });
                    Navigator.pop(context);
                  },
                );
              },
            ),
          ),
          actions: [TextButton(onPressed: () => Navigator.pop(context), child: const Text('キャンセル'))],
        ),
      ),
    );
  }

  void _showDatePicker() {
    showDialog<bool>(
      context: context,
      builder: (context) => DatePickerDialog(initialDate: _expiryDate ?? DateTime.now().add(const Duration(days: 30))),
    );
  }

  void _showSummary() {
    if (_estimateItems.isEmpty) return;

    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('見積書概要'),
        content: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text('見積書番号：$_estimateNumber'),
            const SizedBox(height: 8),
            Text('得意先：${_selectedCustomer?.name ?? '未指定'}'),
            const SizedBox(height: 8),
            Text('合計金額：¥${_totalAmount.toStringAsFixed(2)}'),
            if (_expiryDate != null) Text('有効期限：${DateFormat('yyyy/MM/dd').format(_expiryDate!)}'),
          ],
        ),
        actions: [TextButton(onPressed: () => Navigator.pop(context), child: const Text('閉じる'))],
      ),
    );
  }
}

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

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

/// デイティピッカーダイアログ（簡易）
class DatePickerDialog extends StatefulWidget {
  final DateTime initialDate;
  const DatePickerDialog({super.key, required this.initialDate});

  @override
  State<DatePickerDialog> createState() => _DatePickerDialogState();
}

class _DatePickerDialogState extends State<DatePickerDialog> {
  DateTime _selectedDate = DateTime.now();

  void _selectDate(DateTime date) {
    setState(() => _selectedDate = date);
    Navigator.pop(context, true);
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: const Text('見積有効期限を選択'),
      content: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          ListTile(
            leading: const Icon(Icons.calendar_today),
            title: const Text('今日から 30 日後'),
            onTap: () => _selectDate(DateTime.now().add(const Duration(days: 30))),
          ),
          ListTile(
            leading: const Icon(Icons.access_time),
            title: const Text('1 ヶ月後（約 30 日）'),
            onTap: () => _selectDate(DateTime.now().add(const Duration(days: 30))),
          ),
          ListTile(
            leading: const Icon(Icons.info_outline),
            title: const Text('カスタム日付（簡易：未実装）'),
            subtitle: const Text('デフォルト：30 日後'),
          ),
        ],
      ),
      actions: [
        TextButton(onPressed: () => Navigator.pop(context, false), child: const Text('キャンセル')),
        ElevatedButton(
          onPressed: () => _selectDate(DateTime.now().add(const Duration(days: 30))),
          child: const Text('標準（30 日後）'),
        ),
      ],
    );
  }
}