import logging
from django.db.models.signals import pre_save, post_save
from django.dispatch import receiver
from apps.certificate.models import Certificate
from apps.account.notification_service import create_and_send_notification
from apps.course.models.course import extract_text_from_json, get_localized_field

logger = logging.getLogger(__name__)

@receiver(pre_save, sender=Certificate)
def store_certificate_previous_status(sender, instance, **kwargs):
    if instance.pk:
        try:
            old = Certificate.objects.get(pk=instance.pk)
            instance._previous_status = old.status
        except Certificate.DoesNotExist:
            instance._previous_status = None
    else:
        instance._previous_status = None


@receiver(post_save, sender=Certificate)
def notify_certificate_issued(sender, instance, created, **kwargs):
    # Trigger when status becomes approved
    if instance.status == 'approved':
        was_approved = False
        if created:
            was_approved = True
        elif hasattr(instance, '_previous_status') and instance._previous_status != 'approved':
            was_approved = True
            
        if was_approved:
            course_title_en = get_localized_field('en', instance.course.title)
            course_title_fa = get_localized_field('fa', instance.course.title)
            create_and_send_notification(
                user=instance.student,
                title_en="Certificate Issued",
                body_en=f"Your certificate for '{course_title_en}' has been issued.",
                title_fa="گواهی صادر شد",
                body_fa=f"گواهی پایان دوره شما برای «{course_title_fa}» صادر شد.",
                service='imam-javad',
                data={'type': 'certificate_issued', 'certificate_id': instance.id}
            )