diff --git a/app.py b/app.py
index 75b5cd2..568cad1 100644
--- a/app.py
+++ b/app.py
@@ -5,6 +5,13 @@
 import sentry_sdk
 from sentry_sdk.integrations.flask import FlaskIntegration
 
+class InsufficientInventoryError(Exception):
+    def __init__(self, item_id, requested, available):
+        self.item_id = item_id
+        self.requested = requested
+        self.available = available
+        super().__init__(f"Not enough inventory for item ID {item_id}. Requested: {requested}, Available: {available}")
+
 sentry_sdk.init(
     dsn="https://2ba68720d38e42079b243c9c5774e05c@sentry.io/1316515",
     integrations=[FlaskIntegration()],
@@ -35,15 +42,25 @@ def unhandled_exception():
     'hammer': 1
 }
 
-def process_order(cart):
+def process_order(cart_items_with_quantity):
     global Inventory
-    tempInventory = Inventory
-    for item in cart:
-        if Inventory[item['id']] <= 0:
-            raise Exception("Not enough inventory for " + item['id'])
-        else:
-            tempInventory[item['id']] -= 1
-            print 'Success: ' + item['id'] + ' was purchased, remaining stock is ' + str(tempInventory[item['id']])
+    tempInventory = Inventory.copy()
+    for item in cart_items_with_quantity:
+        item_id_str = str(item['id'])
+        quantity_requested = item['quantity']
+        
+        # Check if item exists in inventory
+        if item_id_str not in tempInventory:
+            raise Exception(f"Item {item_id_str} not found in inventory")
+        
+        # Check if we have enough inventory
+        if tempInventory[item_id_str] < quantity_requested:
+            raise InsufficientInventoryError(item_id_str, quantity_requested, tempInventory[item_id_str])
+        
+        # Decrement inventory by requested quantity
+        tempInventory[item_id_str] -= quantity_requested
+        print('Success: ' + item_id_str + ' was purchased, remaining stock is ' + str(tempInventory[item_id_str]))
+    
     Inventory = tempInventory 
 
 @app.before_request
@@ -65,11 +82,36 @@ def sentry_event_context():
 
 @app.route('/checkout', methods=['POST'])
 def checkout():
-
-    order = json.loads(request.data)
-    print "Processing order for: " + order["email"]
-    cart = order["cart"]
+    try:
+        order_data = json.loads(request.data)
+        print("Processing order for: " + order_data.get("form", {}).get("email", "unknown"))
+        
+        cart = order_data.get("cart", {})
+        cart_items = cart.get("items", [])
+        
+        # Process the cart items for the order
+        processed_cart_for_order = []
+        for item in cart_items:
+            processed_cart_for_order.append({
+                'id': item['id'],
+                'quantity': item['quantity']
+            })
+        
+        process_order(processed_cart_for_order)
+        
+        return json.dumps({"message": "Checkout successful"}), 200, {'ContentType':'application/json'}
     
-    process_order(cart)
-
-    return 'Success'
+    except InsufficientInventoryError as e:
+        sentry_sdk.capture_exception(e)
+        response_data = {
+            "error": "Insufficient inventory", 
+            "itemId": str(e.item_id), 
+            "requested": e.requested, 
+            "available": e.available, 
+            "message": str(e)
+        }
+        return json.dumps(response_data), 409, {'ContentType':'application/json'}
+    
+    except Exception as e:
+        sentry_sdk.capture_exception(e)
+        return json.dumps({"error": "An unexpected error occurred during checkout."}), 500, {'ContentType':'application/json'}