// Version: 1.5 - 請求画面（簡易実装）
import 'package:flutter/material.dart';
import '../models/customer.dart';
import '../models/product.dart';
import '../services/database_helper.dart';

/// 請求書作成・管理画面（簡易実装）
class InvoiceScreen extends StatefulWidget {
  const InvoiceScreen({super.key});

  @override
  State<InvoiceScreen> createState() => _InvoiceScreenState();
}

class _InvoiceScreenState extends State<InvoiceScreen> {
  final _db = DatabaseHelper.instance;

  // UI ステート
  Customer? _selectedCustomer;
  List<Customer> _customers = [];
  String _invoiceNumber = '';

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

  /// 得意先一覧をロード
  Future<void> _loadCustomers() async {
    final customers = await DatabaseHelper.instance.getCustomers();
    setState(() => _customers = customers);
  }

  /// 請求書番号を自動生成（YMM-0001 形式）
  void _generateInvoiceNumber() {
    final now = DateTime.now();
    final yearMonth = '${now.year}${now.month.toString().padLeft(2, '0')}';
    final nextNumber = '0001';
    setState(() => _invoiceNumber = '$yearMonth-$nextNumber');
  }

  /// 請求書保存処理（簡易）
  Future<void> _saveInvoice(Map<String, dynamic> invoiceData) async {
    if (mounted) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('請求書保存しました')),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('請求書')),
      body: _selectedCustomer == null
          ? const Center(child: Text('得意先を選択してください'))
          : SingleChildScrollView(
              child: Padding(
                padding: const EdgeInsets.all(16),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    // 請求書番号表示
                    ListTile(
                      contentPadding: EdgeInsets.zero,
                      title: const Text('請求書番号'),
                      subtitle: Text(_invoiceNumber),
                    ),

                    const Divider(),

                    // 合計金額表示
                    Card(
                      child: ListTile(
                        contentPadding: EdgeInsets.zero,
                        title: const Text('請求書合計'),
                        subtitle: const Text('¥0.00'),
                        trailing: IconButton(icon: const Icon(Icons.edit), onPressed: () {}),
                      ),
                    ),

                    const SizedBox(height: 16),

                    // PDF 帳票出力ボタン（簡易）
                    TextButton.icon(
                      onPressed: () {
                        ScaffoldMessenger.of(context).showSnackBar(
                          const SnackBar(content: Text('PDF 帳票生成中...')),
                        );
                      },
                      icon: const Icon(Icons.download),
                      label: const Text('PDF をダウンロード'),
                    ),
                  ],
                ),
              ),
            ),
    );
  }

}