from rest_framework import generics, permissions, viewsets
from rest_framework.exceptions import PermissionDenied
from rest_framework.response import Response
from rest_framework.views import APIView

from .models import Follow, User
from .serializers import FollowSerializer, ProfileSerializer, RegisterSerializer, UserSerializer


class RegisterView(generics.CreateAPIView):
    queryset = User.objects.all()
    serializer_class = RegisterSerializer
    permission_classes = [permissions.AllowAny]


class MeView(APIView):
    def get(self, request):
        return Response(ProfileSerializer(request.user, context={"request": request}).data)

    def patch(self, request):
        serializer = UserSerializer(request.user, data=request.data, partial=True, context={"request": request})
        serializer.is_valid(raise_exception=True)
        serializer.save()
        return Response(serializer.data)


class UserViewSet(viewsets.ReadOnlyModelViewSet):
    queryset = User.objects.all()
    serializer_class = ProfileSerializer
    lookup_field = "username"


class FollowViewSet(viewsets.ModelViewSet):
    serializer_class = FollowSerializer
    http_method_names = ["get", "post", "delete", "head", "options"]

    def get_queryset(self):
        user = self.request.user
        qs = Follow.objects.select_related("follower", "following")
        direction = self.request.query_params.get("direction", "following")
        if direction == "followers":
            return qs.filter(following=user)
        return qs.filter(follower=user)

    def perform_destroy(self, instance):
        if instance.follower_id != self.request.user.id:
            raise PermissionDenied("Cannot delete another user's follow edge.")
        instance.delete()