// Version: 1.9 - 商品マスタ画面（汎用フォーム実装）
import 'package:flutter/material.dart';
import '../../models/product.dart';
import '../../services/database_helper.dart';
import '../../widgets/master_edit_fields.dart';

/// 商品マスタ管理画面（CRUD 機能付き・汎用フォーム実装）
class ProductMasterScreen extends StatefulWidget {
  const ProductMasterScreen({super.key});

  @override
  State<ProductMasterScreen> createState() => _ProductMasterScreenState();
}

class _ProductMasterScreenState extends State<ProductMasterScreen> {
  List<Product> _products = [];
  bool _loading = true;

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

  Future<void> _loadProducts() async {
    setState(() => _loading = true);
    try {
      final products = await DatabaseHelper.instance.getProducts();
      if (mounted) setState(() => _products = products ?? const <Product>[]);
    } catch (e) {
      if (mounted) ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('読み込みエラー：$e'), backgroundColor: Colors.red),
      );
    } finally {
      setState(() => _loading = false);
    }
  }

  Future<Product?> _showProductDialog({Product? initialProduct}) async {
    final titleText = initialProduct == null ? '新規商品登録' : '商品編集';

    return await showDialog<Product>(
      context: context,
      builder: (context) => AlertDialog(
        title: Text(titleText),
        content: SingleChildScrollView(child: ProductForm(initialProduct: initialProduct)),
        actions: [
          TextButton(onPressed: () => Navigator.pop(context), child: const Text('キャンセル')),
          ElevatedButton(
            onPressed: () => Navigator.pop(context, initialProduct ?? null),
            style: ElevatedButton.styleFrom(backgroundColor: Colors.teal),
            child: initialProduct == null ? const Text('登録') : const Text('更新'),
          ),
        ],
      ),
    );
  }

  void _onAddPressed() async {
    final result = await _showProductDialog();

    if (result != null && mounted) {
      try {
        await DatabaseHelper.instance.insertProduct(result);
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('商品登録完了'), backgroundColor: Colors.green),
        );
        _loadProducts();
      } catch (e) {
        if (mounted) ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('保存エラー：$e'), backgroundColor: Colors.red),
        );
      }
    }
  }

  Future<void> _onEditPressed(int id) async {
    final product = await DatabaseHelper.instance.getProduct(id);
    if (product == null || !mounted) return;

    final result = await _showProductDialog(initialProduct: product);

    if (result != null && mounted) {
      try {
        await DatabaseHelper.instance.updateProduct(result);
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('商品更新完了'), backgroundColor: Colors.green),
        );
        _loadProducts();
      } catch (e) {
        if (mounted) ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('保存エラー：$e'), backgroundColor: Colors.red),
        );
      }
    }
  }

  Future<void> _onDeletePressed(int id) async {
    final product = await DatabaseHelper.instance.getProduct(id);
    if (!mounted) return;

    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('商品削除'),
        content: Text('"${product?.name ?? 'この商品'}"を削除しますか？'),
        actions: [
          TextButton(onPressed: () => Navigator.pop(context), child: const Text('キャンセル')),
          ElevatedButton(
            onPressed: () {
              if (mounted) Navigator.pop(context, true);
            },
            style: ElevatedButton.styleFrom(backgroundColor: Colors.red),
            child: const Text('削除'),
          ),
        ],
      ),
    );

    if (confirmed == true && mounted) {
      try {
        await DatabaseHelper.instance.deleteProduct(id);
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('商品削除完了'), backgroundColor: Colors.green),
        );
        _loadProducts();
      } catch (e) {
        if (mounted) ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('削除エラー：$e'), backgroundColor: Colors.red),
        );
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('/M1. 商品マスタ'),
        actions: [
          IconButton(icon: const Icon(Icons.refresh), onPressed: _loadProducts,),
          IconButton(icon: const Icon(Icons.add), onPressed: _onAddPressed,),
        ],
      ),
      body: _loading ? const Center(child: CircularProgressIndicator()) :
            _products.isEmpty ? Center(child: Text('商品データがありません')) :
            ListView.builder(
              padding: const EdgeInsets.all(8),
              itemCount: _products.length,
              itemBuilder: (context, index) {
                final product = _products[index];
                return Card(
                  margin: const EdgeInsets.only(bottom: 8),
                  child: ListTile(
                    leading: CircleAvatar(backgroundColor: Colors.blue.shade50, child: Icon(Icons.shopping_basket)),
                    title: Text(product.name.isEmpty ? '商品（未入力）' : product.name),
                    subtitle: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
                      Text('コード：${product.productCode}'),
                      Text('単価：¥${(product.unitPrice ?? 0).toStringAsFixed(2)}'),
                    ]),
                    trailing: Row(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        IconButton(icon: const Icon(Icons.edit), onPressed: () => _onEditPressed(product.id ?? 0)),
                        IconButton(icon: const Icon(Icons.delete), onPressed: () => _onDeletePressed(product.id ?? 0)),
                      ],
                    ),
                  ),
                );
              },
            ),
    );
  }
}

/// 商品フォーム部品（汎用フォーム実装）
class ProductForm extends StatefulWidget {
  final Product? initialProduct;

  const ProductForm({super.key, this.initialProduct});

  @override
  State<ProductForm> createState() => _ProductFormState();
}

class _ProductFormState extends State<ProductForm> {
  late TextEditingController _productCodeController;
  late TextEditingController _nameController;
  late TextEditingController _unitPriceController;

  @override
  void initState() {
    super.initState();

    final initialProduct = widget.initialProduct;
    _productCodeController = TextEditingController(text: initialProduct?.productCode ?? '');
    _nameController = TextEditingController(text: initialProduct?.name ?? '');
    _unitPriceController = TextEditingController(text: (initialProduct?.unitPrice ?? 0.0).toString());

    if (_productCodeController.text.isEmpty) {
      _productCodeController = TextEditingController();
    }
    if (_nameController.text.isEmpty) {
      _nameController = TextEditingController();
    }
    if (_unitPriceController.text.isEmpty) {
      _unitPriceController = TextEditingController(text: '0');
    }
  }

  @override
  void dispose() {
    _productCodeController.dispose();
    _nameController.dispose();
    _unitPriceController.dispose();
    super.dispose();
  }

  String? _validateProductCode(String? value) {
    if (value == null || value.isEmpty) {
      return '商品コードは必須です';
    }

    final regex = RegExp(r'^[0-9]+$');
    if (!regex.hasMatch(value)) {
      return '商品コードは数字のみを入力してください（例：9000）';
    }

    return null;
  }

  String? _validateName(String? value) {
    if (value == null || value.isEmpty) {
      return '品名は必須です';
    }
    return null;
  }

  String? _validateUnitPrice(String? value) {
    final price = double.tryParse(value ?? '');
    if (price == null) {
      return '単価は数値を入力してください';
    }

    if (price < 0) {
      return '単価は 0 以上の値です';
    }

    return null;
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        // セクションヘッダー：基本情報
        Padding(
          padding: const EdgeInsets.only(bottom: 8),
          child: Text(
            '基本情報',
            style: Theme.of(context).textTheme.titleMedium?.copyWith(fontWeight: FontWeight.bold),
          ),
        ),

        MasterTextField(
          label: '商品コード',
          hint: '例：9000',
          controller: _productCodeController,
          validator: _validateProductCode,
        ),

        const SizedBox(height: 16),

        MasterTextField(
          label: '品名',
          hint: '商品の名称',
          controller: _nameController,
        ),

        const SizedBox(height: 16),

        MasterNumberField(
          label: '単価（円）',
          hint: '0',
          controller: _unitPriceController,
          validator: _validateUnitPrice,
        ),
      ],
    );
  }
}