"""
Signals for Insurance Approvals app.
Automatically track status changes and create audit trail.
"""

from django.db.models.signals import pre_save, post_save
from django.dispatch import receiver
from .models import InsuranceApprovalRequest, ApprovalStatusHistory


@receiver(pre_save, sender=InsuranceApprovalRequest)
def track_status_change(sender, instance, **kwargs):
    """
    Track status changes before saving.
    Store the old status for comparison in post_save.
    """
    if instance.pk:
        try:
            old_instance = InsuranceApprovalRequest.objects.get(pk=instance.pk)
            instance._old_status = old_instance.status
        except InsuranceApprovalRequest.DoesNotExist:
            instance._old_status = None
    else:
        instance._old_status = None


@receiver(post_save, sender=InsuranceApprovalRequest)
def create_status_history(sender, instance, created, **kwargs):
    """
    Create status history entry when status changes.
    """
    if created:
        # New approval request created
        ApprovalStatusHistory.objects.create(
            approval_request=instance,
            from_status=None,
            to_status=instance.status,
            reason='Initial creation',
            changed_by=instance.created_by
        )
    else:
        # Check if status changed
        old_status = getattr(instance, '_old_status', None)
        if old_status and old_status != instance.status:
            ApprovalStatusHistory.objects.create(
                approval_request=instance,
                from_status=old_status,
                to_status=instance.status,
                reason=f'Status changed from {old_status} to {instance.status}',
                changed_by=instance.created_by  # This should ideally be the current user
            )