Dovodi_Backend/apps/course/signals.py

from apps.course.models import Course
from apps.chat.models import RoomMessage
from apps.course.models.course import Course
from apps.course.models.lesson import CourseLesson
from django.db.models import Q

from django.db.models.signals import post_save, post_delete, pre_save
from django.dispatch import receiver
from django.core.cache import cache
from django.contrib.auth import get_user_model

UserModel = get_user_model()


@receiver(post_save, sender=Course)
def handle_room_message_for_course(sender, instance, created, **kwargs):
    if created:  # فقط برای موارد جدید اجرا شود
        RoomMessage.objects.create(
            name=f"{instance.title} - Group",
            description=f"Group chat for course: {instance.title}",
            initiator=instance.professor,  # استاد به‌عنوان سازنده اتاق
            course=instance,
            room_type=RoomMessage.RoomTypeChoices.GROUP
        )
    else:  # این بخش در زمان آپدیت دوره اجرا می‌شود
        # Find the existing group room for this course and update its details
        RoomMessage.objects.filter(
            course=instance, 
            room_type=RoomMessage.RoomTypeChoices.GROUP
        ).update(
            name=f"{instance.title} - Group",
            description=f"Group chat for course: {instance.title}",
            initiator=instance.professor
        )


@receiver(post_save, sender=Course)
def ensure_professor_role(sender, instance, **kwargs):
    professor = getattr(instance, 'professor', None)
    if professor:
        professor.ensure_professor_profile()

@receiver([post_save, post_delete], sender=Course)
def invalidate_professor_course_cache(sender, instance, **kwargs):
    """
    Clears the cached professor detail page AND their course list 
    whenever a course assigned to them is created, updated, or deleted.
    """
    if instance.professor:
        detail_cache_key = f"professor_detail_{instance.professor.slug}"
        
        cache.delete(detail_cache_key)

# Optional: If you update a Professor's profile in the admin directly
@receiver([post_save, post_delete], sender=UserModel)
def invalidate_professor_profile_cache(sender, instance, **kwargs):
    if instance.user_type == UserModel.UserType.PROFESSOR:
        cache_key = f"professor_detail_{instance.slug}"
        cache.delete(cache_key)

@receiver(post_save, sender=Course)
def sync_course_chat_locks(sender, instance, **kwargs):
    """
    Automatically locks/unlocks the related chat rooms when the admin 
    toggles the chat locks on the Course page.
    """
    # 1. Update the Group Chat
    RoomMessage.objects.filter(
        course=instance,
        room_type=RoomMessage.RoomTypeChoices.GROUP
    ).update(is_locked=instance.is_group_chat_locked)

    # 2. Update the Private Chats between the Professor and Students of this course
    # Get all student IDs enrolled in this course
    student_ids = instance.participants.values_list('student_id', flat=True)
    
    if student_ids:
        RoomMessage.objects.filter(
            room_type=RoomMessage.RoomTypeChoices.PRIVATE
        ).filter(
            # Find rooms where initiator is prof and recipient is student, OR vice versa
            Q(initiator_id=instance.professor_id, recipient_id__in=student_ids) | 
            Q(initiator_id__in=student_ids, recipient_id=instance.professor_id)
        ).update(is_locked=instance.is_professor_chat_locked)


def _recalculate_course_lessons_count(course_id):
    Course.recalculate_lessons_count_for_course(course_id)


@receiver(pre_save, sender=CourseLesson)
def capture_previous_course_lesson_state(sender, instance, **kwargs):
    if not instance.pk:
        instance._previous_course_id = None
        instance._previous_is_active = None
        return

    previous = sender.objects.filter(pk=instance.pk).values('course_id', 'is_active').first()
    if previous:
        instance._previous_course_id = previous['course_id']
        instance._previous_is_active = previous['is_active']
    else:
        instance._previous_course_id = None
        instance._previous_is_active = None


@receiver(post_save, sender=CourseLesson)
def sync_lessons_count_on_course_lesson_save(sender, instance, **kwargs):
    affected_course_ids = {instance.course_id}

    previous_course_id = getattr(instance, '_previous_course_id', None)
    previous_is_active = getattr(instance, '_previous_is_active', None)
    if previous_course_id and previous_course_id != instance.course_id:
        affected_course_ids.add(previous_course_id)

    if previous_is_active is not None and previous_is_active != instance.is_active and previous_course_id:
        affected_course_ids.add(previous_course_id)

    for course_id in affected_course_ids:
        _recalculate_course_lessons_count(course_id)


@receiver(post_delete, sender=CourseLesson)
def sync_lessons_count_on_course_lesson_delete(sender, instance, **kwargs):
    _recalculate_course_lessons_count(instance.course_id)