feat: implement pagination, add activity types and stats views; update category management and localization

backend/server/adventures/views/category_view.py

@@ -0,0 +1,42 @@
+from rest_framework import viewsets
+from rest_framework.decorators import action
+from rest_framework.permissions import IsAuthenticated
+from rest_framework.response import Response
+from adventures.models import Category, Adventure
+from adventures.serializers import CategorySerializer
+
+class CategoryViewSet(viewsets.ModelViewSet):
+    queryset = Category.objects.all()
+    serializer_class = CategorySerializer
+    permission_classes = [IsAuthenticated]
+
+    def get_queryset(self):
+        return Category.objects.filter(user_id=self.request.user)
+
+    @action(detail=False, methods=['get'])
+    def categories(self, request):
+        """
+        Retrieve a list of distinct categories for adventures associated with the current user.
+        """
+        categories = self.get_queryset().distinct()
+        serializer = self.get_serializer(categories, many=True)
+        return Response(serializer.data)
+    
+    def destroy(self, request, *args, **kwargs):
+        instance = self.get_object()
+        if instance.user_id != request.user:
+            return Response({"error": "User does not own this category"}, status
+            =400)
+        
+        if instance.name == 'general':
+            return Response({"error": "Cannot delete the general category"}, status=400)
+        
+        # set any adventures with this category to a default category called general before deleting the category, if general does not exist create it for the user
+        general_category = Category.objects.filter(user_id=request.user, name='general').first()
+
+        if not general_category:
+            general_category = Category.objects.create(user_id=request.user, name='general', icon='🌍', display_name='General')
+        
+        Adventure.objects.filter(category=instance).update(category=general_category)
+
+        return super().destroy(request, *args, **kwargs)