from django.db import models
from simple_history.models import HistoricalRecords
from django.contrib.contenttypes.fields import GenericRelation
from django.utils.timezone import now

class CustomHistoricalRecords(HistoricalRecords):
    """Custom historical records that properly handle generic relations."""
    
    def copy_fields(self, model):
        """
        Copy fields from the model to the historical record model,
        excluding GenericRelation fields.
        """
        fields = {}
        for field in model._meta.concrete_fields:
            if not isinstance(field, GenericRelation) and field.name not in [
                'comments', 'comment_threads', 'photos', 'reviews'
            ]:
                fields[field.name] = field.clone()
        return fields

    def create_history_model(self, model, inherited):
        """
        Override to ensure we don't create duplicate auto fields.
        """
        attrs = {
            '__module__': model.__module__,
            '_history_excluded_fields': ['comments', 'comment_threads', 'photos', 'reviews'],
        }

        app_module = '%s.models' % model._meta.app_label

        if inherited:
            # inherited use models.AutoField instead of models.IntegerField
            attrs.update({
                'id': models.AutoField(primary_key=True),
                'history_id': models.AutoField(primary_key=True),
                'history_date': models.DateTimeField(default=now),
                'history_change_reason': models.CharField(max_length=100, null=True),
                'history_type': models.CharField(max_length=1, choices=(
                    ('+', 'Created'),
                    ('~', 'Changed'),
                    ('-', 'Deleted'),
                )),
                'history_user': models.ForeignKey(
                    'accounts.User',
                    null=True,
                    on_delete=models.SET_NULL,
                    related_name='+'
                ),
            })

        # Convert field to point to historical model
        fields = self.copy_fields(model)
        attrs.update(fields)
        
        return type(
            str('Historical%s' % model._meta.object_name),
            (models.Model,),
            attrs
        )