Dovodi_Backend/apps/course/signals.py

import logging
from django.utils import timezone
from apps.course.models import Course
from apps.chat.models import RoomMessage
from apps.course.models.course import Course, extract_text_from_json
from apps.course.models.lesson import CourseLesson
from apps.course.models.live_session import LiveSessionRecording
from django.db.models import Q

logger = logging.getLogger(__name__)

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):
    title_str = extract_text_from_json(instance.title)
    if created:  # فقط برای موارد جدید اجرا شود
        RoomMessage.objects.create(
            name=f"{title_str} - Group",
            description=f"Group chat for course: {title_str}",
            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"{title_str} - Group",
            description=f"Group chat for course: {title_str}",
            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)


@receiver(post_save, sender=LiveSessionRecording)
def create_course_lesson_from_recording(sender, instance, **kwargs):
    """
    Automatically creates a CourseChapter (if not exists) and CourseLesson
    whenever a LiveSessionRecording is saved with a valid file.
    """
    if not instance.file:
        return

    # To avoid duplicate creation if save is called multiple times
    from apps.course.models.lesson import Lesson, CourseChapter, CourseLesson
    if Lesson.objects.filter(content_file=instance.file.name).exists():
        return

    session = instance.session
    course = session.course
    
    # 1. Determine chapter title as recording date (YYYY-MM-DD)
    date_val = instance.created_at or timezone.now()
    recording_date_str = date_val.strftime('%Y-%m-%d')
    
    # 2. Get or create CourseChapter for this date
    from apps.course.models.course import extract_text_from_json
    chapter = None
    for ch in CourseChapter.objects.filter(course=course):
        if extract_text_from_json(ch.title) == recording_date_str:
            chapter = ch
            break
            
    if not chapter:
        chapter = CourseChapter.objects.create(
            course=course,
            title=recording_date_str,
            is_active=True
        )
        
    # 3. Determine lesson title: use custom title or subject (with parts if multiple recordings exist)
    base_title = session.recording_title or session.subject
    
    # Get all recordings for this session, ordered by creation
    recordings = list(LiveSessionRecording.objects.filter(session=session).order_by('created_at', 'id'))
    recordings_count = len(recordings)
    
    if recordings_count <= 1:
        lesson_title = base_title
    else:
        try:
            current_index = recordings.index(instance) + 1
        except ValueError:
            current_index = recordings_count
            
        lesson_title = f"{base_title} part {current_index}"
        
        # Retroactively rename the first lesson if this is a subsequent recording
        if current_index > 1:
            first_recording = recordings[0]
            if first_recording.file:
                first_lesson = Lesson.objects.filter(content_file=first_recording.file.name).first()
                if first_lesson:
                    first_lesson_title = f"{base_title} part 1"
                    first_lesson.title = first_lesson_title
                    first_lesson.save(update_fields=['title'])
                    
                    # Also update corresponding CourseLesson
                    CourseLesson.objects.filter(lesson=first_lesson).update(title=first_lesson_title)
    
    # 4. Calculate duration in minutes
    duration_minutes = 0
    if instance.file_time:
        duration_minutes = int(instance.file_time.total_seconds() / 60)
        if duration_minutes == 0 and instance.file_time.total_seconds() > 0:
            duration_minutes = 1

    # 5. Create the Lesson object
    lesson = Lesson.objects.create(
        title=lesson_title,
        content_type="video_file",
        content_file=instance.file,
        duration=duration_minutes
    )
    
    # 6. Create the CourseLesson object linking it to the chapter
    course_lesson = CourseLesson.objects.create(
        course=course,
        chapter=chapter,
        lesson=lesson,
        title=lesson_title,
        is_active=True
    )
    
    logger.info(f"✨ [Signal] Automatically created CourseLesson {course_lesson.id} ({lesson_title}) for course {course.id} from recording {instance.id}")