from django.contrib.contenttypes.models import ContentType

from rest_framework.serializers import (
    ValidationError
)

def create_comment_serializer(model_type='post', slug=None, parent_id=None):
    class CommentCreateSerializer(ModelSerializer):
        class Meta:
            model = Comment
            fields = [
                'id',
                'parent',
                'content',
                'timestamp',
            ]
        def __init__(self, *args, **kwargs):
            self.model_type = model_type
            self.slug = slug
            self.parent_obj = None
            if parent_id:
                parent_qs = Comment.objects.filter(id=parent_id)
                if parent_qs.exists() and parent_qs.count() ==1:
                    self.parent_obj = parent_qs.first()
            return super(CommentCreateSerializer, self).__init__(*args, **kwargs)
        def validate(self, data):
            model_type = self.model_type
            model_qs = ContentType.objects.filter(model=model_type)
            if not model_qs.exists() or model_qs.count() != 1:
                raise ValidationError("This is not a valid content type")
            SomeModel = model_qs.first().model_class()
            obj_qs = SomeModel.objects.filter(slug=self.slug)
            if not obj_qs.exists() or obj_qs.count() != 1:
                raise ValidationError("This is not a slug for this content type")
            return data
    return CommentCreateSerializer