Cart rendering, bug fixes with cart adding/rming

services/orders.py

@@ -1,6 +1,8 @@
 import logging
 from sqlalchemy.ext.asyncio import AsyncSession
+from config import PAGE_SIZE
 from db.models.orders import OrderStatus
+from dto.cart import CartDTO, CartItemDTO
 from repositories.order_items import OrderItemRepository
 from repositories.orders import OrderRepository
 
@@ -44,6 +46,7 @@ class OrderService:
             order_item = await self.order_items_repo.create_order_item(
                 session, order_id=order.id, product_id=product_id, quantity=quantity
             )
+            return quantity
         else:
             await self.order_items_repo.update_order_item_quantity(
                 session, order_item.id, quantity=order_item.quantity + quantity
@@ -75,13 +78,37 @@ class OrderService:
                 "attempt of decreasing quantity of non-existing order_item, potential callback_query exploit, ignoring..."
             )
 
-        new_quantity = max(0, order_item.quantity - quantity)
-        await self.order_items_repo.update_order_item_quantity(
-            session, order_item_id=order_item.id, quantity=new_quantity
-        )
+        new_quantity = order_item.quantity - quantity
+        if new_quantity > 0:
+            await self.order_items_repo.update_order_item_quantity(
+                session, order_item_id=order_item.id, quantity=new_quantity
+            )
+        else:
+            await self.order_items_repo.delete_item(session, order_item.id)
 
         return new_quantity
 
+    async def clear_from_cart(
+        self, session: AsyncSession, *, customer: int, product_id: int
+    ):
+        order = await self.order_repo.get_draft_order_by_user(session, customer)
+
+        if not order:
+            raise OrderServiceException(
+                "attempt of removing product from non-existing cart, potential callback_query exploit, ignoring..."
+            )
+
+        order_item = await self.order_items_repo.get_item_by_order_and_product(
+            session, order_id=order.id, product_id=product_id
+        )
+
+        if not order_item:
+            raise OrderServiceException(
+                "attempt of decreasing quantity of non-existing order_item, potential callback_query exploit, ignoring..."
+            )
+
+        await self.order_items_repo.delete_item(session, item_id=order_item.id)
+
     async def get_cart_product_amount(
         self, session: AsyncSession, *, customer: int, product_id: int
     ) -> int:
@@ -127,7 +154,40 @@ class OrderService:
         if not order:
             return 0
 
-        order_item = await self.order_items_repo.get_items_by_order(
-            session, order_id=order.id
+        return await self.order_items_repo.get_items_count(session, order_id=order.id)
+
+    async def build_cart_dto(
+        self,
+        session: AsyncSession,
+        *,
+        customer: int,
+        limit: int = PAGE_SIZE + 1,
+        offset: int = 0,
+    ) -> CartDTO:
+        order = await self.order_repo.get_draft_order_by_user(session, customer)
+        cart_items = []
+
+        if not order:
+            return CartDTO(items=cart_items, total=0)
+
+        order_items = await self.order_items_repo.get_items_by_order(
+            session, order_id=order.id, limit=limit, offset=offset
         )
-        return len(order_item)
+
+        total = 0
+
+        for item in order_items:
+            if item.quantity <= 0:
+                await self.order_items_repo.delete_item(session, item_id=item.id)
+                continue
+
+            cart_item = CartItemDTO(
+                product_id=item.product_id,
+                name=item.product.name,
+                quantity=item.quantity,
+                price=item.product.price,
+            )
+            cart_items.append(cart_item)
+            total += cart_item.total
+
+        return CartDTO(items=cart_items, total=total)