Hotfix/refactoring

apps/products/serializers.py

@@ -1,3 +1,5 @@
+from datetime import date
+
 from rest_framework import serializers
 from rest_framework.relations import PrimaryKeyRelatedField
 
@@ -15,6 +17,16 @@ class Meta:
         model = PriceInterval
         fields = '__all__'
 
+    def validate(self, data):
+        if data['start_date'] > data['end_date']:
+            raise serializers.ValidationError("start_date can not be bigger than end_date.")
+        return data
+
+    def validate_end_date(self, value):
+        if not value:
+            return date.max
+        return value
+
 
 class ProductStatsSerializer(serializers.Serializer):
     product = PrimaryKeyRelatedField(queryset=Product.objects.all(), required=True)

apps/products/utils/price_counter.py

@@ -0,0 +1,39 @@
+from typing import Dict
+from datetime import timedelta
+
+from apps.products.models import PriceInterval
+
+
+class Prices:
+    def __init__(self, data: dict):
+        self.data: dict = data
+        self.price = 0
+        self.days = 0
+
+    def query_records(self):
+        return PriceInterval.objects.filter(
+            product=self.data.get('product'),
+            end_date__gte=self.data.get('start_date'),
+            start_date__lte=self.data.get('end_date')
+        )
+
+    def get_average(self) -> Dict:
+        for record in self.query_records():
+            if record.start_date > self.data.get('start_date'):
+                start_date = record.start_date
+            else:
+                start_date = self.data.get('start_date')
+
+            if record.end_date < self.data.get('end_date'):
+                end_date = record.end_date
+            else:
+                end_date = self.data.get('end_date')
+
+            days = end_date - start_date + timedelta(days=1)
+
+            self.price += record.price * days.days
+            self.days += days.days
+        return {
+            "price": self.price / self.days,
+            "days": (self.data.get('end_date') - self.data.get('start_date') + timedelta(days=1)).days
+        }

apps/products/utils/price_validator.py

@@ -0,0 +1,47 @@
+from datetime import timedelta
+
+
+class PriceValidator:
+    def __init__(self, serializer, queryset):
+        self.serializer = serializer
+        self.validated_data = serializer.validated_data
+        self.queryset = queryset
+
+    def get_existing_price_query(self, process_date):
+        """Get already existing prices for submitted dates."""
+        prices = self.queryset.filter(
+            start_date__lt=process_date,
+            end_date__gt=process_date).first()
+        return prices
+
+    def update_date_intervals(self, start_date_query, end_date_query):
+        """Update date intervals for dates that persist within current dates."""
+        if start_date_query:
+            start_date_query.end_date = self.validated_data.get('start_date') - timedelta(days=1)
+            start_date_query.save()
+        if end_date_query:
+            end_date_query.start_date = self.validated_data.get('end_date') + timedelta(days=1)
+            end_date_query.save()
+
+    def clear_existing_range(self):
+        """Clears outdated prices within submitted dates."""
+        self.queryset.filter(
+            start_date__gte=self.validated_data.get('start_date'),
+            end_date__lte=self.validated_data.get('end_date')
+        ).delete()
+
+    def validate_save_data(self):
+        if self.queryset:
+            self.update_date_intervals(
+                start_date_query=self.get_existing_price_query(self.validated_data.get('start_date')),
+                end_date_query=self.get_existing_price_query(self.validated_data.get('end_date'))
+            )
+        self.serializer.save()
+
+    def insert_price(self):
+        self.queryset = self.queryset.filter(product=self.validated_data.get('product')).order_by('start_date')
+        if not self.queryset:
+            self.serializer.save()
+        else:
+            self.clear_existing_range()
+            self.validate_save_data()

apps/products/views.py

@@ -1,8 +1,13 @@
 from drf_util.views import BaseViewSet, BaseCreateModelMixin, BaseListModelMixin
+from rest_framework import status
+from rest_framework.decorators import action
 from rest_framework.permissions import AllowAny
+from rest_framework.response import Response
 
 from apps.products.models import Product, PriceInterval
-from apps.products.serializers import ProductSerializer, PriceIntervalSerializer
+from apps.products.serializers import ProductSerializer, PriceIntervalSerializer, ProductStatsSerializer
+from apps.products.utils.price_counter import Prices
+from apps.products.utils.price_validator import PriceValidator
 
 
 class ProductViewSet(BaseListModelMixin, BaseCreateModelMixin, BaseViewSet):
@@ -11,7 +16,16 @@ class ProductViewSet(BaseListModelMixin, BaseCreateModelMixin, BaseViewSet):
     serializer_class = ProductSerializer
     queryset = Product.objects.all()
 
-    # TODO create here a new endpoint for stats
+    @action(detail=False, methods=['GET'])
+    def stats(self, request, *args, **kwargs):
+        serializer = ProductStatsSerializer(data=request.query_params)
+
+        if not serializer.is_valid():
+            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
+
+        average_prices = Prices(serializer.validated_data)
+        average_prices.get_average()
+        return Response(average_prices, status=status.HTTP_200_OK)
 
 
 class ProductPriceViewSet(BaseListModelMixin, BaseCreateModelMixin, BaseViewSet):
@@ -20,4 +34,13 @@ class ProductPriceViewSet(BaseListModelMixin, BaseCreateModelMixin, BaseViewSet)
     serializer_class = PriceIntervalSerializer
     queryset = PriceInterval.objects.all()
 
-    # TODO create interval here
+    def create(self, request, *args, **kwargs):
+        serializer = self.serializer_class(data=request.data)
+
+        if not serializer.is_valid():
+            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
+
+        interval_inserter = PriceValidator(serializer, self.queryset)
+        interval_inserter.insert_price()
+        return Response(serializer.data, status=status.HTTP_201_CREATED)
+

requirements.txt

@@ -14,4 +14,5 @@ django-nose==1.4.7
 django-extensions==3.2.1
 jsonschema==3.2.0
 PyJWT==1.7.1
-django-filter==22.1
+django-filter==22.1
+psycopg2-binary==2.9.5