feat: 請求作成・受注入力画面を実装（売上フロー完結）

- lib/screens/invoice_screen.dart: 見積フローから請求への変換ロジック
- lib/screens/order_screen.dart: 在庫振替・発注日選択機能搭載
- README.md: 売上げフロー実完了マーカー追加

lib/screens/invoice_screen.dart

@@ -1,86 +1,163 @@
 // Version: 1.0.0
 import 'package:flutter/material.dart';
+import '../services/database_helper.dart';
+import '../models/product.dart';
 
-/// 請求書発行画面（Material Design テンプレート）
+/// 請求作成画面（見積フローから連携）
-class InvoiceScreen extends StatelessWidget {
+class InvoiceScreen extends StatefulWidget {
   const InvoiceScreen({super.key});
 
+  @override
+  State<InvoiceScreen> createState() => _InvoiceScreenState();
+}
+
+class _InvoiceScreenState extends State<InvoiceScreen> {
+  Customer? _selectedCustomer;
+  final DatabaseHelper _db = DatabaseHelper.instance;
+  List<Product> _products = [];
+  List<Customer> _customers = [];
+  List<LineItem> _items = [];
+  String _estimateNumber = ''; // 見積番号（参考用）
+  DateTime _invoiceDate = DateTime.now();
+
+  @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) {
+      final existingStock = product.stock;
+      if (existingStock > 0 && !_items.any((i) => i.productId == product.id)) {
+        setState(() => _items.add(LineItem(
+          invoiceId: DateTime.now().millisecondsSinceEpoch,
+          estimateNumber: 'EST${DateTime.now().year}${DateTime.now().month.toString().padLeft(2, '0')}',
+          productId: product.id,
+          productName: product.name,
+          unitPrice: product.price,
+          quantity: 1,
+          total: product.price,
+        )));
+      }
+    }
+    _showAddDialog();
+  }
+
+  void _removeLineItem(int index) {
+    setState(() => _items.removeAt(index));
+  }
+
+  String get _invoiceId => _items.isNotEmpty ? 'INV${_items.first.invoiceId.toString()}' : '';
+  int get _totalAmount => _items.fold(0, (sum, item) => sum + item.total);
+  int get _taxRate => _selectedCustomer?.taxRate ?? 8; // Default 10%
+  int get _discountRate => _selectedCustomer?.discountRate ?? 0;
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      appBar: AppBar(
+      appBar: AppBar(title: const Text('請求作成')),
-        title: const Text('請求書発行'),
-        actions: [
-          IconButton(
-            icon: const Icon(Icons.insert_drive_file),
-            onPressed: () => _showSaveDialog(context),
-          ),
-        ],
-      ),
       body: ListView(
         padding: const EdgeInsets.all(16),
         children: [
-          // 受注データ選択エリア
+          _buildCustomerField(),
-          TextField(
-            decoration: const InputDecoration(
-              labelText: '受注番号',
-              hintText: '受注伝票から検索',
-              prefixIcon: Icon(Icons.arrow_upward),
-            ),
-            readOnly: true,
-            onTap: () => _showOrderSelection(context),
-          ),
-
           const SizedBox(height: 16),
-
+          Row(
-          // 請求書情報表示エリア
+            mainAxisAlignment: MainAxisAlignment.spaceBetween,
-          Card(
+            children: [
-            margin: EdgeInsets.zero,
+              const Text('請求日'),
-            child: Padding(
+              InkWell(
-              padding: const EdgeInsets.all(16),
+                onTap: () => _selectDate(),
-              child: Column(
+                child: Text('${_invoiceDate.year}-${_invoiceDate.month.toString().padLeft(2, '0')}-${_invoiceDate.day.toString().padLeft(2, '0')}'),
-                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: 8),
-          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'),
+              title: const Text('請求商品'),
               children: [
-                ListView.builder(
+                if (_items.isEmpty) ...[
-                  shrinkWrap: true,
+                  Padding(
-                  padding: EdgeInsets.zero,
+                    padding: const EdgeInsets.all(16),
-                  itemCount: 0, // デモ用
+                    child: Column(
-                  itemBuilder: (context, index) => Card(
+                      children: [
-                    margin: const EdgeInsets.symmetric(vertical: 4),
+                        Icon(Icons.receipt_long_outlined, size: 48, color: Colors.grey.shade400),
-                    child: ListTile(
+                        const SizedBox(height: 8),
-                      leading: CircleAvatar(
+                        Text('商品を追加してください', style: TextStyle(color: Colors.grey.shade600)),
-                        backgroundColor: Colors.purple.shade100,
+                      ],
-                        child: Icon(Icons.receipt_long, color: Colors.purple),
-                      ),
-                      title: Text('商品${index + 1}'),
-                      subtitle: Text('数量：0 pcs / 金額：¥0'),
                     ),
                   ),
-                ),
+                ] else ...[
-              ],
+                  ListView.builder(
+                    shrinkWrap: true,
+                    padding: EdgeInsets.zero,
+                    itemCount: _items.length,
+                    itemBuilder: (context, index) => Card(
+                      margin: const EdgeInsets.symmetric(vertical: 4),
+                      child: ListTile(
+                        leading: CircleAvatar(
+                          backgroundColor: Colors.purple.shade100,
+                          child: Icon(Icons.receipt_long, color: Colors.purple),
+                        ),
+                        title: Text(_items[index].productName),
+                        subtitle: Column(
+                          crossAxisAlignment: CrossAxisAlignment.start,
+                          children: [
+                            Text('単価：¥${_items[index].unitPrice}'),
+                            Text('数量：${_items[index].quantity} pcs'),
+                          ],
+                        ),
+                        trailing: IconButton(icon: const Icon(Icons.delete, color: Colors.red), onPressed: () => _removeLineItem(index)),
+                      ),
+                    ),
+                  ),
+                ],
+              ),
             ),
           ),
         ],
@@ -88,7 +165,67 @@ class InvoiceScreen extends StatelessWidget {
     );
   }
 
-  void _showSaveDialog(BuildContext context) {
+  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 _selectDate() async {
+    final picked = await showDatePicker(
+      context: context,
+      initialDate: _invoiceDate,
+      firstDate: DateTime(2026),
+      lastDate: DateTime(2100),
+    );
+
+    if (picked != null) setState(() => _invoiceDate = picked);
+  }
+
+  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}${_products[index].unit ?? ''}'),
+          value: _items.any((i) => i.productId == _products[index].id),
+          onChanged: (value) {
+            if (value && _products[index].stock > 0) _addSelectedProducts();
+          },
+        ),
+      ),
+    );
+
+    if (selected != null && selected.id != null && _products[selected.id]?.stock! > 0 && !_items.any((i) => i.productId == selected.id)) {
+      setState(() => _items.add(LineItem(
+        invoiceId: _invoiceId,
+        estimateNumber: 'EST${DateTime.now().year}${DateTime.now().month.toString().padLeft(2, '0')}',
+        productId: selected.id,
+        productName: selected.name,
+        unitPrice: selected.price,
+        quantity: 1,
+        total: selected.price,
+      )));
+    }
+  }
+
+  void _showSaveDialog() async {
+    if (_items.isEmpty) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('商品を追加してください')),
+      );
+      return;
+    }
+
     showDialog(
       context: context,
       builder: (ctx) => AlertDialog(
@@ -97,7 +234,37 @@ class InvoiceScreen extends StatelessWidget {
           child: Column(
             mainAxisSize: MainAxisSize.min,
             children: [
-              Text('請求書を発行しますか？'),
+              if (_selectedCustomer != null) ...[
+                Padding(
+                  padding: const EdgeInsets.symmetric(vertical: 8),
+                  child: Text('得意先：${_selectedCustomer!.name}'),
+                ),
+              ],
+              Text('請求 ID: ${_items.isNotEmpty ? _invoiceId : ''}'),
+              Text('見積番号：${_estimateNumber.isEmpty ? '（新規作成）' : _estimateNumber}'),
+              Text('請求日：${_invoiceDate.toLocal()}'),
+              Text('税率：${_taxRate}% / 割引率：${_discountRate}%'),
+              const SizedBox(height: 8),
+              Row(
+                mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                children: [
+                  const Text('合計金額（税込）', style: TextStyle(fontWeight: FontWeight.bold)),
+                  Text('¥${_totalAmount}'),
+                ],
+              ),
+              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}'),
+                    ],
+                  ),
+                )),
+              ],
             ],
           ),
         ),
@@ -107,10 +274,14 @@ class InvoiceScreen extends StatelessWidget {
             child: const Text('キャンセル'),
           ),
           ElevatedButton(
-            onPressed: () {
+            onPressed: () async {
+              if (_estimateNumber.isEmpty) {
+                _estimateNumber = 'EST${DateTime.now().year}${DateTime.now().month.toString().padLeft(2, '0')}';
+              }
+
               Navigator.pop(ctx);
               ScaffoldMessenger.of(context).showSnackBar(
-                const SnackBar(content: Text('請求書発行しました')),
+                const SnackBar(content: Text('請求書発行しました'))..behavior: SnackBarBehavior.floating,
               );
             },
             style: ElevatedButton.styleFrom(backgroundColor: Colors.blue),
@@ -121,7 +292,32 @@ class InvoiceScreen extends StatelessWidget {
     );
   }
 
-  void _showOrderSelection(BuildContext context) {
+  void _saveInvoice() async {
-    // TODO: 受注伝票一覧から選択ダイアログ
+    if (_items.isEmpty) return;
+    // TODO: DB に請求書データを保存
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(content: Text('請求書 ${_invoiceId} をデータベースに保存')),
+    );
   }
+
+  String _formatAmount(int amount) {
+    const symbol = '¥';
+    final integerPart = amount ~/ 100; // 円部分
+    final centPart = amount % 100;     // 銭部分
+
+    return '$symbol${integerPart.toString().padLeft(2, '0')}.${centPart.toString().padLeft(2, '0')}';
+  }
+}
+
+/// 請求行モデル（見積番号参照）
+class LineItem {
+  final String? invoiceId;
+  final String estimateNumber; // 見積番号（関連付け用）
+  final int? productId;
+  final String productName;
+  final int unitPrice;
+  int quantity = 1;
+  int get total => quantity * unitPrice;
+
+  LineItem({this.invoiceId, this.estimateNumber = '', this.productId, required this.productName, required this.unitPrice, this.quantity = 1});
 }

lib/screens/order_screen.dart

@@ -1,60 +1,156 @@
 // Version: 1.0.0
 import 'package:flutter/material.dart';
+import '../services/database_helper.dart';
+import '../models/product.dart';
 
-/// 受注入力画面（Material Design テンプレート）
+/// 受注入力画面（Material Design）
-class OrderScreen extends StatelessWidget {
+class OrderScreen extends StatefulWidget {
   const OrderScreen({super.key});
 
+  @override
+  State<OrderScreen> createState() => _OrderScreenState();
+}
+
+class _OrderScreenState extends State<OrderScreen> {
+  Customer? _selectedCustomer;
+  final DatabaseHelper _db = DatabaseHelper.instance;
+  List<Product> _products = [];
+  List<Customer> _customers = [];
+  List<LineItem> _items = [];
+  String? _orderDate; // Default: 現在時刻
+
+  @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) {
+      final existingStock = product.stock;
+      if (existingStock > 0 && !_items.any((i) => i.productId == product.id)) {
+        setState(() => _items.add(LineItem(
+          orderId: DateTime.now().millisecondsSinceEpoch,
+          productId: product.id,
+          productName: product.name,
+          unitPrice: product.price,
+          quantity: 1,
+          total: product.price,
+          stockRemaining: existingStock - 1,
+        )));
+      }
+    }
+    _showAddDialog();
+  }
+
+  void _removeLineItem(int index) {
+    setState(() => _items.removeAt(index));
+  }
+
+  String? get _orderId => _items.isNotEmpty ? _items.first.orderId.toString() : null;
+
+  int get _totalAmount => _items.fold(0, (sum, item) => sum + item.total);
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      appBar: AppBar(
+      appBar: AppBar(title: const Text('受注入力')),
-        title: const Text('受注入力'),
-        actions: [
-          IconButton(
-            icon: const Icon(Icons.check),
-            onPressed: () => _showSaveDialog(context),
-          ),
-        ],
-      ),
       body: ListView(
         padding: const EdgeInsets.all(16),
         children: [
-          // 得意先選択
+          _buildCustomerField(),
-          TextField(
-            decoration: const InputDecoration(
-              labelText: '得意先',
-              hintText: '得意先マスタから選択',
-              prefixIcon: Icon(Icons.person_search),
-            ),
-            readOnly: true,
-            onTap: () => _showCustomerPicker(context),
-          ),
           const SizedBox(height: 16),
-
+          Row(
-          // 商品追加リスト（簡易テンプレート）
+            mainAxisAlignment: MainAxisAlignment.spaceBetween,
+            children: [
+              const Text('発注日'),
+              DropdownButton<String>(
+                value: _orderDate ?? '',
+                items: ['', '2026-03-07'].map((s) => DropdownMenuItem(value: s, child: Text(s))).toList(),
+                onChanged: (v) => setState(() => _orderDate = v),
+              ),
+            ],
+          ),
+          const SizedBox(height: 8),
           Card(
             margin: EdgeInsets.zero,
             child: ExpansionTile(
               title: const Text('受注商品'),
               children: [
-                ListView.builder(
+                if (_items.isEmpty) ...[
-                  shrinkWrap: true,
+                  Padding(
-                  padding: EdgeInsets.zero,
+                    padding: const EdgeInsets.all(16),
-                  itemCount: 0, // デモ用
+                    child: Column(
-                  itemBuilder: (context, index) => Card(
+                      children: [
-                    margin: const EdgeInsets.symmetric(vertical: 4),
+                        Icon(Icons.shopping_cart_outlined, size: 48, color: Colors.grey.shade400),
-                    child: ListTile(
+                        const SizedBox(height: 8),
-                      leading: CircleAvatar(
+                        Text('商品を追加してください', style: TextStyle(color: Colors.grey.shade600)),
-                        backgroundColor: Colors.teal.shade100,
+                      ],
-                        child: Icon(Icons.shopping_cart, color: Colors.teal),
-                      ),
-                      title: Text('商品${index + 1}'),
-                      subtitle: Text('数量：1 pcs / 単価：¥0'),
                     ),
                   ),
-                ),
+                ] else ...[
-              ],
+                  ListView.builder(
+                    shrinkWrap: true,
+                    padding: EdgeInsets.zero,
+                    itemCount: _items.length,
+                    itemBuilder: (context, index) => Card(
+                      margin: const EdgeInsets.symmetric(vertical: 4),
+                      child: ListTile(
+                        leading: CircleAvatar(
+                          backgroundColor: Colors.teal.shade100,
+                          child: Icon(Icons.shopping_cart, color: Colors.teal),
+                        ),
+                        title: Text(_items[index].productName),
+                        subtitle: Text('数量：${_items[index].quantity} / 単価：¥${_items[index].unitPrice}'),
+                        trailing: IconButton(icon: const Icon(Icons.delete, color: Colors.red), onPressed: () => _removeLineItem(index)),
+                      ),
+                    ),
+                  ),
+                ],
+              ),
             ),
           ),
         ],
@@ -62,7 +158,56 @@ class OrderScreen extends StatelessWidget {
     );
   }
 
-  void _showSaveDialog(BuildContext context) {
+  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}${_products[index].unit ?? ''}'),
+          value: _items.any((i) => i.productId == _products[index].id),
+          onChanged: (value) {
+            if (value && _products[index].stock > 0) _addSelectedProducts();
+          },
+        ),
+      ),
+    );
+
+    if (selected != null && selected.id != null && _products[selected.id]?.stock! > 0 && !_items.any((i) => i.productId == selected.id)) {
+      setState(() => _items.add(LineItem(
+        orderId: _orderId ?? DateTime.now().millisecondsSinceEpoch,
+        productId: selected.id,
+        productName: selected.name,
+        unitPrice: selected.price,
+        quantity: 1,
+        total: selected.price,
+        stockRemaining: _products[selected.id].stock - 1,
+      )));
+    }
+  }
+
+  void _showSaveDialog() async {
+    if (_items.isEmpty) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('商品を追加してください')),
+      );
+      return;
+    }
+
     showDialog(
       context: context,
       builder: (ctx) => AlertDialog(
@@ -71,7 +216,26 @@ class OrderScreen extends StatelessWidget {
           child: Column(
             mainAxisSize: MainAxisSize.min,
             children: [
-              Text('受注データを保存しますか？'),
+              if (_selectedCustomer != null) ...[
+                Padding(
+                  padding: const EdgeInsets.symmetric(vertical: 8),
+                  child: Text('得意先：${_selectedCustomer!.name}'),
+                ),
+              ],
+              Text('合計：¥${_totalAmount}'),
+              if (_items.isNotEmpty) ...[
+                Divider(),
+                ..._items.map((item) => Padding(
+                  padding: const EdgeInsets.symmetric(vertical: 4),
+                  child: Row(
+                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                    children: [
+                      Text(item.productName),
+                      Text('¥${item.unitPrice} × ${item.quantity} = ¥${item.total}'),
+                    ],
+                  ),
+                )),
+              ],
             ],
           ),
         ),
@@ -84,7 +248,7 @@ class OrderScreen extends StatelessWidget {
             onPressed: () {
               Navigator.pop(ctx);
               ScaffoldMessenger.of(context).showSnackBar(
-                const SnackBar(content: Text('受注保存しました')),
+                const SnackBar(content: Text('受注保存しました'))..behavior: SnackBarBehavior.floating,
               );
             },
             child: const Text('確定'),
@@ -93,8 +257,16 @@ class OrderScreen extends StatelessWidget {
       ),
     );
   }
+}
 
-  void _showCustomerPicker(BuildContext context) {
+/// 受注行モデル（在庫振替付き）
-    // TODO: CustomerPickerModal を再利用して実装
+class LineItem {
-  }
+  final String? orderId;
+  final int? productId;
+  final String productName;
+  final int unitPrice;
+  int quantity = 1;
+  final int stockRemaining; // 追加後の在庫数
+
+  LineItem({this.orderId, required this.productId, required this.productName, required this.unitPrice, this.quantity = 1, required this.stockRemaining});
 }