h-1.flutter.4/lib/screens/invoice_screen.dart

// Version: 1.0.0
import 'package:flutter/material.dart';

/// 請求書発行画面（Material Design テンプレート）
class InvoiceScreen extends StatelessWidget {
  const InvoiceScreen({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('請求書発行'),
        actions: [
          IconButton(
            icon: const Icon(Icons.insert_drive_file),
            onPressed: () => _showSaveDialog(context),
          ),
        ],
      ),
      body: ListView(
        padding: const EdgeInsets.all(16),
        children: [
          // 受注データ選択エリア
          TextField(
            decoration: const InputDecoration(
              labelText: '受注番号',
              hintText: '受注伝票から検索',
              prefixIcon: Icon(Icons.arrow_upward),
            ),
            readOnly: true,
            onTap: () => _showOrderSelection(context),
          ),

          const SizedBox(height: 16),

          // 請求書情報表示エリア
          Card(
            margin: EdgeInsets.zero,
            child: Padding(
              padding: const EdgeInsets.all(16),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  Text('請求書総額', style: const TextStyle(fontWeight: FontWeight.bold)),
                  Text('¥0', style: const TextStyle(fontSize: 24, color: Colors.green)),
                  const SizedBox(height: 8),
                  Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: [
                      Text('請求元：'),
                      Text('株式会社サンプル'),
                    ],
                  ),
                ],
              ),
            ),
          ),

          const SizedBox(height: 16),

          // 商品リスト（簡易テンプレート）
          Card(
            margin: EdgeInsets.zero,
            child: ExpansionTile(
              title: const Text('請求書商品'),
              children: [
                ListView.builder(
                  shrinkWrap: true,
                  padding: EdgeInsets.zero,
                  itemCount: 0, // デモ用
                  itemBuilder: (context, index) => Card(
                    margin: const EdgeInsets.symmetric(vertical: 4),
                    child: ListTile(
                      leading: CircleAvatar(
                        backgroundColor: Colors.purple.shade100,
                        child: Icon(Icons.receipt_long, color: Colors.purple),
                      ),
                      title: Text('商品${index + 1}'),
                      subtitle: Text('数量：0 pcs / 金額：¥0'),
                    ),
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  void _showSaveDialog(BuildContext context) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('請求書発行'),
        content: SingleChildScrollView(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text('請求書を発行しますか？'),
            ],
          ),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: const Text('キャンセル'),
          ),
          ElevatedButton(
            onPressed: () {
              Navigator.pop(ctx);
              ScaffoldMessenger.of(context).showSnackBar(
                const SnackBar(content: Text('請求書発行しました')),
              );
            },
            style: ElevatedButton.styleFrom(backgroundColor: Colors.blue),
            child: const Text('発行'),
          ),
        ],
      ),
    );
  }

  void _showOrderSelection(BuildContext context) {
    // TODO: 受注伝票一覧から選択ダイアログ
  }
}