from django.db import models
from django.conf import settings
from django.contrib.contenttypes.fields import GenericRelation, GenericForeignKey
from typing import List, Type

def get_trackable_fields(model_class: Type[models.Model]) -> List[models.Field]:
    """Get fields that should be tracked in history."""
    if getattr(model_class, '_is_historical_model', False):
        # For historical models, only return core history fields
        return [
            models.BigAutoField(name='id', primary_key=True),
            models.DateTimeField(name='history_date'),
            models.CharField(name='history_change_reason', max_length=100, null=True),
            models.CharField(name='history_type', max_length=1),
            models.ForeignKey(
                to=settings.AUTH_USER_MODEL,
                name='history_user',
                null=True,
                on_delete=models.SET_NULL
            )
        ]
    
    trackable_fields = []
    excluded_fields = {
        'comment_threads', 'comments', 'photos', 'reviews',
        'thread', 'content_type', 'object_id', 'content_object'
    }
    
    for field in model_class._meta.get_fields():
        # Skip fields we don't want to track
        if any([
            isinstance(field, (GenericRelation, GenericForeignKey)),
            field.name in excluded_fields,
            field.is_relation and hasattr(field.remote_field.model, '_meta') and
            'commentthread' in field.remote_field.model._meta.model_name.lower()
        ]):
            continue
            
        trackable_fields.append(field)
    
    return trackable_fields

class HistoricalFieldsMixin:
    """Mixin that controls which fields are copied to historical models."""
    
    @classmethod
    def get_fields_to_track(cls) -> List[models.Field]:
        """Get fields that should be tracked in history."""
        return get_trackable_fields(cls)