from djoser.serializers import UserSerializer as BaseUserSerializer
from rest_framework.serializers import ModelSerializer
from rest_framework import serializers
from accounts.models import CustomUser
from drf_extra_fields.fields import Base64ImageField
from user_groups.serializers import SimpleUserGroupSerializer
from django.core.cache import cache
from django.core import exceptions as django_exceptions
from rest_framework.settings import api_settings
from django.contrib.auth.password_validation import validate_password
# There can be multiple subject instances with the same name, only differing in course, year level, and semester. We filter them here


class SimpleCustomUserSerializer(ModelSerializer):
    class Meta(BaseUserSerializer.Meta):
        model = CustomUser
        fields = ('id', 'username', 'email', 'full_name')


class CustomUserSerializer(BaseUserSerializer):
    avatar = Base64ImageField()

    class Meta(BaseUserSerializer.Meta):
        model = CustomUser
        fields = ('id', 'username', 'email', 'avatar', 'first_name',
                  'last_name', 'user_group', 'group_member', 'group_owner')
        read_only_fields = ('id', 'username', 'email', 'user_group',
                            'group_member', 'group_owner')

    def to_representation(self, instance):
        representation = super().to_representation(instance)
        representation['user_group'] = SimpleUserGroupSerializer(
            instance.user_group, many=False).data
        return representation

    def update(self, instance, validated_data):
        cache.delete(f'user:{instance.id}')
        return super().update(instance, validated_data)


class UserRegistrationSerializer(serializers.ModelSerializer):
    email = serializers.EmailField(required=True)
    username = serializers.CharField(required=True)
    password = serializers.CharField(
        write_only=True, style={'input_type': 'password', 'placeholder': 'Password'})
    first_name = serializers.CharField(
        required=True, allow_blank=False, allow_null=False)
    last_name = serializers.CharField(
        required=True, allow_blank=False, allow_null=False)

    class Meta:
        model = CustomUser
        fields = ['email', 'username', 'password',
                  'first_name', 'last_name']

    def validate(self, attrs):
        user_attrs = attrs.copy()
        user = self.Meta.model(**user_attrs)
        password = attrs.get("password")

        try:
            validate_password(password, user)
        except django_exceptions.ValidationError as e:
            serializer_error = serializers.as_serializer_error(e)
            errors = serializer_error[api_settings.NON_FIELD_ERRORS_KEY]
            if len(errors) > 1:
                raise serializers.ValidationError({"password": errors[0]})
            else:
                raise serializers.ValidationError({"password": errors})
        if self.Meta.model.objects.filter(username=attrs.get("username")).exists():
            raise serializers.ValidationError(
                "A user with that username already exists.")
        return super().validate(attrs)

    def create(self, validated_data):
        user = self.Meta.model(**validated_data)
        user.username = validated_data['username']
        user.is_active = False
        user.set_password(validated_data['password'])
        user.save()

        return user