from rest_framework.authtoken.serializers import AuthTokenSerializer
from rest_framework import serializers

from django.utils.translation import ugettext_lazy as _


class FunAuthTokenSerializer(AuthTokenSerializer):
    '''
    Adds specific authentication validation for FUN API.
    '''

    def validate(self, attrs):
        super(FunAuthTokenSerializer, self).validate(attrs)
        user = attrs['user']
        if user.is_staff or user.is_superuser:
            return attrs
        raise serializers.ValidationError(_('User is not staff member.'))


class UpdateSerializerMixin(object):
    '''
    Helpers and common functionalities for update serializers,
    for instance for Course and University validation on update.
    '''

    def validate(self, data):
        if self.instance.prevent_auto_update:
            raise serializers.ValidationError(
                'Updating "{}" is not allowed'.format(self.instance)
            )
        return data