feat: stock module

stock/services.py

@@ -0,0 +1,104 @@
+from . import models
+from django.utils import timezone
+import logging
+
+
+logger = logging.getLogger(__name__)
+
+
+def find_inventory(product_id: int, warehouse_id: int) -> models.Inventory | None:
+    """根据产品ID和仓库ID查找库存记录"""
+
+    try:
+        inventory = models.Inventory.objects.get(
+            product_id=product_id,
+            warehouse_id=warehouse_id,
+        )
+        return inventory
+    except models.Inventory.DoesNotExist:
+        return None
+
+
+def create_stock_snapshot(stock_change_record: models.StockChangeRecord, inventory: models.Inventory) -> models.StockSnapshot:
+    """创建库存快照记录"""
+
+    if not stock_change_record or stock_change_record.id is None:
+        raise ValueError("无效的库存变动记录")
+
+    delta = stock_change_record.delta
+
+    # 必须在库存变动发生后创建快照
+    snapshot = models.StockSnapshot(
+        product_id=inventory.product_id,
+        warehouse_id=inventory.warehouse_id,
+        delta=delta,
+        quantity_before=inventory.quantity - delta,
+        quantity_after=inventory.quantity,
+        stock_change_record_id=stock_change_record.id,
+        unit=stock_change_record.unit,
+        num_of_rolls=stock_change_record.num_of_rolls or 1,
+    )
+    snapshot.save()
+    logger.info(
+        f'创建库存快照，库存ID: {inventory.id}, 数量: {inventory.quantity}, '
+        f'匹数: {inventory.num_of_rolls}'
+    )
+    return snapshot
+
+
+def make_stock_change_completed(stock_change_record: models.StockChangeRecord) -> bool:
+    """处理库存变动完成后的逻辑"""
+    # TODO: 这里可以添加事务处理以确保数据一致性
+
+    if not stock_change_record or stock_change_record.id is None:
+        # 无效的库存变动记录
+        return False
+
+    if stock_change_record.is_finished:
+        return True
+
+    inventory_record = find_inventory(
+        product_id=stock_change_record.product_id,
+        warehouse_id=stock_change_record.warehouse_id,
+    )
+
+    if not inventory_record:
+        logger.info(
+            f'库存记录未找到，产品ID: {stock_change_record.product_id}, '
+            f'仓库ID: {stock_change_record.warehouse_id}，正在创建新的库存记录。'
+        )
+
+        # 如果没有找到库存记录且为入库，则创建一个新的库存记录
+
+        inventory_record = models.Inventory(
+            product_id=stock_change_record.product_id,
+            warehouse_id=stock_change_record.warehouse_id,
+            quantity=stock_change_record.delta,
+            num_of_rolls=stock_change_record.num_of_rolls or 0,
+            minimum_quantity=0,
+        )
+        logger.info(
+            f'创建新的库存记录，产品ID: {inventory_record.product_id}, '
+            f'仓库ID: {inventory_record.warehouse_id}, 数量: {inventory_record.quantity},'
+            f'匹数: {inventory_record.num_of_rolls}'
+        )
+    else:
+        # 更新现有库存记录
+        inventory_record.quantity += stock_change_record.delta
+        if stock_change_record.num_of_rolls:
+            inventory_record.num_of_rolls += stock_change_record.num_of_rolls
+        
+        logger.info(
+            f'更新库存记录 {inventory_record.id}，新数量: {inventory_record.quantity}, '
+            f'新匹数: {inventory_record.num_of_rolls}'
+        )
+
+    inventory_record.save()
+    create_stock_snapshot(stock_change_record, inventory_record)
+    stock_change_record.is_finished = True
+    stock_change_record.finished_at = timezone.now()
+    stock_change_record.save()
+    logger.info(
+        f'库存变动记录 {stock_change_record.id} 标记为已完成。'
+    )
+    return True