from django.db.models.signals import post_save, post_delete
from django.dispatch import receiver
from channels.layers import get_channel_layer
from asgiref.sync import async_to_sync
from .models import Expense

@receiver(post_save, sender=Expense)
def expense_saved(sender, instance, created, **kwargs):
    channel_layer = get_channel_layer()
    action = 'created' if created else 'updated'
    
    expense_data = {
        'id': instance.id,
        'amount': str(instance.amount),
        'category': instance.category.name if instance.category else None,
        'project': instance.project.name if instance.project else None,
        'user': instance.user.username if instance.user else None,
        'date': instance.date.strftime('%Y-%m-%d'),
        'description': instance.description,
    }

    async_to_sync(channel_layer.group_send)(
        'expenses_updates',
        {
            'type': 'expense_update',
            'action': action,
            'expense': expense_data
        }
    )

@receiver(post_delete, sender=Expense)
def expense_deleted(sender, instance, **kwargs):
    channel_layer = get_channel_layer()
    async_to_sync(channel_layer.group_send)(
        'expenses_updates',
        {
            'type': 'expense_update',
            'action': 'deleted',
            'expense': {'id': instance.id}
        }
    )