// Version: 1.0.0
import 'package:flutter/material.dart';
import '../services/database_helper.dart';
import '../models/product.dart';

/// 見積入力画面（Material Design テンプレート）
class EstimateScreen extends StatefulWidget {
  const EstimateScreen({super.key});

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

class _EstimateScreenState extends State<EstimateScreen> {
  Customer? _selectedCustomer;
  final DatabaseHelper _db = DatabaseHelper.instance;
  List<Product> _products = [];
  List<Customer> _customers = [];
  List<LineItem> _items = [];

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

  Future<void> _loadProducts() async {
    try {
      final products = await _db.getProducts();
      setState(() => _products = products);
    } catch (e) {
      debugPrint('Product loading failed: $e');
    }
  }

  Future<void> _loadCustomers() async {
    try {
      final customers = await _db.getCustomers();
      setState(() => _customers = customers.where((c) => c.isDeleted == 0).toList());
    } catch (e) {
      debugPrint('Customer loading failed: $e');
    }
  }

  Future<void> _showCustomerPicker() async {
    if (_customers.isEmpty) await _loadCustomers();

    final selected = await showModalBottomSheet<Customer>(
      context: context,
      builder: (ctx) => SizedBox(
        height: MediaQuery.of(context).size.height * 0.4,
        child: ListView.builder(
          padding: const EdgeInsets.all(8),
          itemCount: _customers.length,
          itemBuilder: (ctx, index) => ListTile(
            title: Text(_customers[index].name),
            subtitle: Text('コード：${_customers[index].customerCode}'),
            onTap: () => Navigator.pop(ctx, _customers[index]),
          ),
        ),
      ),
    );

    if (selected is Customer && selected.id != _selectedCustomer?.id) {
      setState(() => _selectedCustomer = selected);
    }
  }

  void _addSelectedProducts() async {
    for (final product in _products) {
      setState(() => _items.add(LineItem(
        productId: product.id,
        productName: product.name,
        unitPrice: product.price,
        quantity: 1,
        total: product.price,
      )));
    }
    _showAddDialog();
  }

  void _removeLineItem(int index) {
    setState(() => _items.removeAt(index));
  }

  void _updateLineItemQuantity(int index, int quantity) {
    setState(() {
      _items[index].quantity = quantity;
      _items[index].total = quantity * _items[index].unitPrice;
    });
  }

  void _showSaveDialog() {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('見積確定'),
        content: SingleChildScrollView(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              if (_selectedCustomer != null) ...[
                Padding(
                  padding: const EdgeInsets.symmetric(vertical: 8),
                  child: Text('得意先：${_selectedCustomer!.name}'),
                ),
              ],
              Text('合計：¥${_calculateTotal()}'),
              if (_items.isNotEmpty) ...[
                Divider(),
                ..._items.map((item) => Padding(
                  padding: const EdgeInsets.symmetric(vertical: 4),
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: [
                      Text(item.productName),
                      Text('¥${item.unitPrice} × ${item.quantity} = ¥${item.total}'),
                    ],
                  ),
                )),
              ],
            ],
          ),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: const Text('キャンセル'),
          ),
          ElevatedButton(
            onPressed: () async {
              if (_items.isEmpty) {
                ScaffoldMessenger.of(context).showSnackBar(
                  const SnackBar(content: Text('商品を追加してください')),
                );
                return;
              }
              Navigator.pop(ctx);
              ScaffoldMessenger.of(context).showSnackBar(
                const SnackBar(content: Text('見積保存しました'))..behavior: SnackBarBehavior.floating,
              );
            },
            child: const Text('確定'),
          ),
        ],
      ),
    );
  }

  int _calculateTotal() {
    return _items.fold(0, (sum, item) => sum + item.total);
  }

  Widget _buildEmptyState() {
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Icon(Icons.receipt_long, size: 64, color: Colors.grey.shade400),
          const SizedBox(height: 16),
          Text('見積商品を追加してください', style: TextStyle(color: Colors.grey.shade600)),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('見積入力')),
      body: ListView(
        padding: const EdgeInsets.all(16),
        children: [
          _buildCustomerField(),
          const SizedBox(height: 16),
          Card(
            margin: EdgeInsets.zero,
            child: ExpansionTile(
              title: const Text('見積商品'),
              children: [
                if (_items.isEmpty) ...[
                  Padding(
                    padding: const EdgeInsets.all(16),
                    child: _buildEmptyState(),
                  ),
                ] else ...[
                  ListView.builder(
                    shrinkWrap: true,
                    padding: EdgeInsets.zero,
                    itemCount: _items.length,
                    itemBuilder: (context, index) => Card(
                      margin: const EdgeInsets.symmetric(vertical: 4),
                      child: ListTile(
                        leading: CircleAvatar(
                          backgroundColor: Colors.blue.shade100,
                          child: Icon(Icons.receipt, color: Colors.blue),
                        ),
                        title: Text(_items[index].productName),
                        subtitle: Text('単価：¥${_items[index].unitPrice}'),
                        trailing: IconButton(icon: const Icon(Icons.delete, color: Colors.red), onPressed: () => _removeLineItem(index)),
                      ),
                    ),
                  ),
                ],
              ],
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildCustomerField() {
    return TextField(
      decoration: InputDecoration(
        labelText: '得意先',
        hintText: _selectedCustomer != null ? _selectedCustomer.name : '得意先マスタから選択',
        prefixIcon: Icon(Icons.person_search),
        isReadOnly: true,
      ),
      onTap: () => _showCustomerPicker(),
    );
  }

  void _showAddDialog() async {
    final selected = await showModalBottomSheet<Product>(
      context: context,
      builder: (ctx) => ListView.builder(
        padding: EdgeInsets.zero,
        itemCount: _products.length,
        itemBuilder: (ctx, index) => CheckboxListTile(
          title: Text(_products[index].name),
          subtitle: Text('¥${_products[index].price} / 在庫：${_products[index].stock}${_products[index].unit ?? ''}'),
          value: _items.any((i) => i.productId == _products[index].id),
          onChanged: (value) {
            if (value) _addSelectedProducts();
          },
        ),
      ),
    );

    if (selected != null && selected.id != null && !_items.any((i) => i.productId == selected.id)) {
      setState(() => _items.add(LineItem(
        productId: selected.id,
        productName: selected.name,
        unitPrice: selected.price,
        quantity: 1,
        total: selected.price,
      )));
    }
  }
}

/// 見積行モデル
class LineItem {
  final int? productId;
  final String productName;
  final int unitPrice;
  int quantity = 1;
  int get total => quantity * unitPrice;

  LineItem({required this.productId, required this.productName, required this.unitPrice, this.quantity = 1});
}