from django.contrib.auth import get_user_model
from django.contrib.auth.tokens import default_token_generator
from django.contrib.contenttypes.models import ContentType
from django.db import models
from django.utils.http import urlsafe_base64_decode
from rest_framework import serializers, status
from rest_framework.response import Response
from rest_framework.views import APIView

from djeveric.signals import user_confirmed, AlreadyConfirmed


class ConfirmationSerializer(serializers.Serializer):
    uid = serializers.CharField()
    token = serializers.CharField()
    type_id = serializers.CharField()
    obj_id = serializers.CharField()


class ConfirmationView(APIView):
    def post(self, request, format=None):
        serializer = ConfirmationSerializer(data=request.data)
        if serializer.is_valid():
            user = self.get_user(serializer.validated_data["uid"])
            token = serializer.validated_data["token"]
            if user is not None and default_token_generator.check_token(user, token):
                obj = self.get_obj(serializer.validated_data["type_id"], serializer.validated_data["obj_id"])
                if obj is not None:
                    try:
                        user_confirmed.send(sender=self.__class__, user=user, instance=obj, key=None)
                    except AlreadyConfirmed as e:
                        return Response({"message": str(e)}, status=status.HTTP_400_BAD_REQUEST)
                    return Response(serializer.data, status=status.HTTP_204_NO_CONTENT)

        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    def get_obj(self, type_id, obj_id):
        try:
            # urlsafe_base64_decode() decodes to bytestring
            type_pk = urlsafe_base64_decode(type_id).decode()
            obj_pk = urlsafe_base64_decode(obj_id).decode()
            obj = ContentType.objects.get_for_id(type_pk).get_object_for_this_type(pk=obj_pk)
        except (TypeError, ValueError, OverflowError, models.Model.DoesNotExist):
            obj = None
        return obj

    def get_user(self, uid):
        try:
            # urlsafe_base64_decode() decodes to bytestring
            uid = urlsafe_base64_decode(uid).decode()
            user = get_user_model().objects.get(pk=uid)
        except (TypeError, ValueError, OverflowError, models.Model.DoesNotExist):
            user = None
        return user