rancher service & quota usage service

apps/herd/services/rancher_service.py

@@ -0,0 +1,13 @@
+from django.db.models import Sum, functions, Value
+
+
+class RancherService:
+
+    @staticmethod
+    def get_total_used_weight(rancher, sale_item):
+        return sale_item.objects.filter(
+            transaction__rancher=rancher,
+            transaction__transaction_status='success'
+        ).aggregate(
+            total_weight=functions.Coalesce(Sum('weight'), Value(0))
+        )['total_weight']

apps/herd/services/services.py

@@ -1,8 +1,13 @@
 from decimal import Decimal
 from apps.herd.models import Rancher
 from apps.livestock.models import LiveStock
-from apps.warehouse.models import InventoryEntry
+from apps.warehouse.models import (
+    InventoryEntry,
+    InventoryQuotaSaleItem
+)
+from django.db.models import Sum
 from apps.product.models import Quota, QuotaDistribution
+from apps.herd.services.rancher_service import RancherService
 from django.db.models import Count, Q
 import typing
 
@@ -89,11 +94,13 @@ def rancher_quota_weight(rancher, inventory_entry: InventoryEntry = None, distri
             # incentive plan quantity by this livestock type
             rancher_plan_weight = rancher_plans.first().allowed_quantity * item.quantity_kg
             total_weight += rancher_plan_weight
-    print(total_weight)
+
+    # get rancher remaining usage of quota for purchase
+    rancher_remaining_usage = RancherService.get_total_used_weight(rancher, InventoryQuotaSaleItem)
 
     return {
         "total_weight": total_weight,
-        "remaining_weight": 20,
+        "remaining_weight": total_weight - rancher_remaining_usage,
         "by_type": [{
             "name": key,
             "name_fa": value['name_fa'],