from django.conf import settings
import logging

from django.contrib.auth import get_user_model
from django.db.models import Count, Q, F
from django.shortcuts import get_object_or_404
from django.utils import timezone

from drf_yasg import openapi
from drf_yasg.utils import swagger_auto_schema
from rest_framework import status
from rest_framework.authtoken.models import Token
from rest_framework.exceptions import NotFound
from rest_framework.filters import SearchFilter
from rest_framework.generics import GenericAPIView, ListAPIView, RetrieveAPIView
from rest_framework.permissions import AllowAny, IsAuthenticated
from rest_framework.response import Response

logger = logging.getLogger(__name__)


from apps.course.serializers import (
    CourseListSerializer, CourseCategorySerializer, CourseDetailSerializer,
    CourseAttachmentSerializer, CourseGlossarySerializer, MyCourseListSerializer,
    OnlineClassTokenCreateSerializer, OnlineClassTokenVerifySerializer
)
from apps.course.models import (
    Course,
    CourseAttachment,
    CourseCategory,
    CourseGlossary,
    CourseLiveSession,
    LiveSessionUser,
    Participant,
)
from apps.course.doc import *
from apps.course.services.plugnmeet import PlugNMeetClient, PlugNMeetError
from apps.account.serializers import UserProfileSerializer
from utils.exceptions import AppAPIException
from utils.redis import OnlineClassTokenManager


UserModel = get_user_model()


class CourseCategoryAPIView(ListAPIView):
    queryset = CourseCategory.objects.all()
    serializer_class = CourseCategorySerializer
    
    @swagger_auto_schema(
        operation_description=doc_course_category(),
        tags=["Imam-Javad - Course"]
    )
    def get(self, request, *args, **kwargs):
        return super().get(request, *args, **kwargs)        
    
        
    

class CourseListAPIView(ListAPIView):
    serializer_class = CourseListSerializer
    filter_backends = [SearchFilter]
    search_fields = ['title', 'category__name', 'professor__fullname']

    @swagger_auto_schema(
        tags=['Imam-Javad - Course'],
    operation_description=doc_course_list(),
    manual_parameters=[
        openapi.Parameter(
            'search', openapi.IN_QUERY,
            description="Search by course title, category name, or professor's full name",
            type=openapi.TYPE_STRING,
        ),
        openapi.Parameter(
            'category_slug', openapi.IN_QUERY,
            description="Category of the Course",
            type=openapi.TYPE_STRING,
            # enum=[category.slug for category in CourseCategory.objects.all()]
        ),
        openapi.Parameter(
            'status', openapi.IN_QUERY,
            type=openapi.TYPE_STRING,
            description="""Status =>
            Upcoming (visible but registration not allowed)---Предстоящие
            Registering (registration is open)---регистрация
            Ongoing (course has started, registration closed)---Впроцессе
            Finished (course has ended)---закончился
            """,
            enum=[status for status in ['upcoming', 'registering', 'ongoing', 'finished']]
        ),
        openapi.Parameter(
            'is_free', openapi.IN_QUERY,
            description="Ценообразование is_free <bool>",
            type=openapi.TYPE_BOOLEAN,
        ),
        openapi.Parameter(
            'is_online', openapi.IN_QUERY,
            description="Статус участия is_online <bool>",
            type=openapi.TYPE_BOOLEAN,
        ),
    ])
    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)

    def get_queryset(self):
        """
        Optimized queryset with select_related for ForeignKey relationships and filtering
        """
        queryset = Course.objects.select_related(
            'category',
            'professor'
        ).exclude(status=Course.StatusChoices.INACTIVE)

        request = self.request
        filters = request.query_params

        # Handle category_slug with multiple values separated by commas
        if category_slugs := filters.get('category_slug'):
            category_slugs_list = category_slugs.split(',')
            queryset = queryset.filter(category__slug__in=category_slugs_list)

        # Handle status with multiple values separated by commas
        if statuses := filters.get('status'):
            statuses_list = statuses.split(',')
            queryset = queryset.filter(status__in=statuses_list)

        if is_free := filters.get('is_free'):
            is_free = is_free.lower() == 'true'
            queryset = queryset.filter(
                Q(is_free=is_free) | Q(price=0) if is_free else Q(is_free=False, price__gt=0)
            )
        if is_online := filters.get('is_online'):
            is_online = is_online.lower() == 'true'
            queryset = queryset.filter(is_online=is_online)

        return queryset
    
    
    
    
    
class CourseDetailAPIView(RetrieveAPIView):
    serializer_class = CourseDetailSerializer
    lookup_field = "slug"

    @swagger_auto_schema(
        tags=["Imam-Javad - Course"],
        operation_description="Get detailed information about a specific course",
        responses={
            200: openapi.Response(
                description="Course details",
                schema=CourseDetailSerializer()
            )
        }
    )
    def get(self, request, *args, **kwargs):
        return super().get(request, *args, **kwargs)

    def get_queryset(self):
        """
        Optimized queryset with select_related and prefetch_related for all relationships
        """
        return Course.objects.select_related(
            'category',
            'professor'
        ).prefetch_related(
            'lessons__lesson',
            'lessons__completions',
            'attachments__attachment',
            'glossaries__glossary',
            'participants__student',
            'room_messages'
        )

    @swagger_auto_schema(
        operation_description=doc_course_detail(),
        tags=['Imam-Javad - Course'],
    )
    def get(self, request, *args, **kwargs):
        return super().get(request, *args, **kwargs)        
        

class MyCourseListAPIView(ListAPIView):
    serializer_class = MyCourseListSerializer
    permission_classes = [IsAuthenticated]  

    @swagger_auto_schema(manual_parameters=[
        openapi.Parameter(
            'completed', openapi.IN_QUERY,
            description="мои курсы completed <bool> true",
            type=openapi.TYPE_BOOLEAN,
        ),
        openapi.Parameter(
            'certificate', openapi.IN_QUERY,
            type=openapi.TYPE_BOOLEAN,
        ),
    ],
    operation_description=doc_courses_my_courses(),
    operation_summary="Home",
    tags=['Imam-Javad - Course']

    )
    def get(self, request, *args, **kwargs):
        print(f'--> my-course-> {request}/ {kwargs}')
        return super().get(request, *args, **kwargs)        
        
    def get_queryset(self):
        """
        Optimized queryset for user's courses with select_related and prefetch_related
        """
        queryset = Course.objects.select_related(
            'category',
            'professor'
        ).prefetch_related(
            'lessons__lesson',
            'lessons__completions',
            'participants__student'
        ).exclude(status=Course.StatusChoices.INACTIVE)

        request = self.request
        filters = request.query_params
        student = self.request.user
        qs = queryset.filter(participants__student=student)
        completed_only = filters.get('completed', '').lower() == 'true'
        if completed_only == True:
            # نمایش دوره‌هایی که همه درس‌هایشان توسط کاربر تکمیل شده‌اند
            qs = qs.annotate(
                total_lessons=Count('lessons', distinct=True),
                completed_lessons=Count(
                    'lessons__completions',
                    filter=Q(lessons__completions__student=student),
                    distinct=True
                )
            ).filter(total_lessons=F('completed_lessons'))
        elif completed_only == False:
            # نمایش دوره‌هایی که همه درس‌هایشان تکمیل نشده‌اند
            qs = qs.annotate(
                total_lessons=Count('lessons', distinct=True),
                completed_lessons=Count(
                    'lessons__completions',
                    filter=Q(lessons__completions__student=student),
                    distinct=True
                )
            ).filter(total_lessons__gt=F('completed_lessons'))

        if 'completed' not in filters:
            certificate = filters.get('certificate', '').lower() == 'true'
            if certificate:
                qs = qs.exclude(
                    course_certificates__student=student,
                    course_certificates__status__in=['pending', 'approved']
                )
            
        return qs

    


class AttachmentListAPIView(ListAPIView):
    serializer_class = CourseAttachmentSerializer
    
    @swagger_auto_schema(
        tags=['Imam-Javad - Course'],
        manual_parameters=[
            openapi.Parameter(
                'slug', openapi.IN_PATH,
                description="Slug of the Course",
                type=openapi.TYPE_STRING,
                required=True  
            )
        ],
        operation_description="Retrieve a list of attachments for a given course by its slug."
    )
    def get(self, request, *args, **kwargs):
        return super().get(request, *args, **kwargs)

    def get_queryset(self):
        """
        Optimized queryset with select_related for attachment relationship
        """
        course_slug = self.kwargs.get('slug')
        try:
            course = Course.objects.get(slug=course_slug)
        except Course.DoesNotExist:
            raise NotFound("Course not found")
        return CourseAttachment.objects.select_related(
            'course',
            'attachment'
        ).filter(course=course)
    
    


class GlossaryListAPIView(ListAPIView):
    serializer_class = CourseGlossarySerializer
    filter_backends = [SearchFilter]
    search_fields = ['glossary__title', 'glossary__description']

    @swagger_auto_schema(
        operation_description="Get glossary terms for a specific course",
        tags=["Imam-Javad - Course"],
        manual_parameters=[
            openapi.Parameter(
                'slug', openapi.IN_PATH,
                description="Course slug",
                type=openapi.TYPE_STRING,
                required=True
            ),
            openapi.Parameter(
                'search', openapi.IN_QUERY,
                description="Search in glossary title or description",
                type=openapi.TYPE_STRING,
                required=False
            )
        ],
        responses={
            200: openapi.Response(
                description="List of glossary terms",
                schema=CourseGlossarySerializer(many=True)
            )
        }
    )
    def get(self, request, *args, **kwargs):
        return super().get(request, *args, **kwargs)

    def get_queryset(self):
        """
        Optimized queryset with select_related for glossary relationship
        """
        course_slug = self.kwargs.get('slug')
        try:
            course = Course.objects.get(slug=course_slug)
        except Course.DoesNotExist:
            raise NotFound("Course not found")

        return CourseGlossary.objects.select_related(
            'course',
            'glossary'
        ).filter(course=course)
    
    

class CourseOnlineClassTokenAPIView(GenericAPIView):
    permission_classes = [IsAuthenticated]
    serializer_class = OnlineClassTokenCreateSerializer

    @swagger_auto_schema(
        tags=['Imam-Javad - Course'],
        operation_description="Generate a temporary entry token for an online class.",
        request_body=OnlineClassTokenCreateSerializer,
        responses={
            status.HTTP_201_CREATED: openapi.Response(
                description="Token generated successfully.",
                examples={
                    "application/json": {
                        "token": "abc123xyz789...",
                        "url": "https://imamjavad.newhorizonco.uk/join-class?token=abc123xyz789...&slug=python-basics",
                        "expires_in": 300,
                    }
                }
            )
        }
    )
    def post(self, request, pk, *args, **kwargs):
        serializer = self.get_serializer(data=request.data or {})
        serializer.is_valid(raise_exception=True)

        course = get_object_or_404(Course, pk=pk)
        if not course.is_online:
            raise AppAPIException({'message': "Course is not marked as online."}, status_code=status.HTTP_400_BAD_REQUEST)

        if not self._user_has_access(request.user, course):
            raise AppAPIException({'message': "You do not have access to this course."}, status_code=status.HTTP_403_FORBIDDEN)

        manager = OnlineClassTokenManager()
        user_token, _ = Token.objects.get_or_create(user=request.user)
        identifier = f"{request.user.id}:{user_token.key[:8]}"
        token = manager.generate_token(course_id=course.id, user_identifier=identifier)

        manager.store_token(token, {
            'course_id': course.id,
            'user_id': request.user.id,
            'user_token': user_token.key,
            'course_slug': course.slug,
            'extra': {
                'professor_in_class': False,
            },
        })

        # ساخت URL ثابت با token و course slug
        entry_url = f"https://imamjavad.newhorizonco.uk/join-class?token={token}&slug={course.slug}"

        return Response({
            'token': token,
            'url': entry_url,
            'expires_in': getattr(settings, 'ONLINE_CLASS_TOKEN_TTL', 300),
        }, status=status.HTTP_201_CREATED)

    @staticmethod
    def _user_has_access(user, course: Course) -> bool:
        if user.is_staff or course.professor_id == user.id:
            return True
        return Participant.objects.filter(course=course, student=user).exists()


class CourseOnlineClassTokenValidateAPIView(GenericAPIView):
    permission_classes = [AllowAny]
    serializer_class = OnlineClassTokenVerifySerializer

    def get_permissions(self):
        if self.request.method == 'GET':
            return [IsAuthenticated()]
        return [AllowAny()]

    @swagger_auto_schema(
        tags=['Imam-Javad - Course'],
        operation_description="Get course and user data for authenticated user.",
        manual_parameters=[
            openapi.Parameter(
                'slug', openapi.IN_PATH,
                description="Course Slug",
                type=openapi.TYPE_STRING,
                required=True
            )
        ],
        responses={
            status.HTTP_200_OK: openapi.Response(
                description="Course data retrieved.",
                examples={
                    "application/json": {
                        "course": {"id": 1, "title": "Sample Course"},
                        "user": {"id": 10, "fullname": "John Doe"},
                        "metadata": {
                            "status": "ongoing",
                            "has_started": True,
                            "professor_in_class": False,
                            "validated_at": "2024-01-01T10:00:00Z"
                        }
                    }
                }
            )
        }
    )
    def get(self, request, slug, *args, **kwargs):
        detail_view = CourseDetailAPIView()
        queryset = detail_view.get_queryset()
        course = get_object_or_404(queryset, slug=slug)
        user = request.user

        # DEPRECATED: Polling approach replaced by webhook integration
        # Room status is now updated automatically via PlugNMeet webhooks
        # self._sync_room_status_with_plugnmeet(course)

        course_data = CourseDetailSerializer(course, context={'request': request}).data
        user_data = UserProfileSerializer(user, context={'request': request}).data
        metadata = self._build_metadata(
            course,
            {'user_id': user.id, 'extra': {}, 'generated_at': timezone.now().isoformat()},
            user=user,
        )

        return Response({
            'course': course_data,
            'user': user_data,
            'metadata': metadata,
        }, status=status.HTTP_200_OK)

    @swagger_auto_schema(
        tags=['Imam-Javad - Course'],
        operation_description="Validate an online class entry token and return course/user data.",
        request_body=OnlineClassTokenVerifySerializer,
        responses={
            status.HTTP_200_OK: openapi.Response(
                description="Token validated.",
                examples={
                    "application/json": {
                        "course": {"id": 1, "title": "Sample Course"},
                        "user": {"id": 10, "fullname": "John Doe"},
                        "metadata": {
                            "status": "ongoing",
                            "has_started": True,
                            "professor_in_class": False,
                            "validated_at": "2024-01-01T10:00:00Z"
                        }
                    }
                }
            )
        }
    )
    def post(self, request, *args, **kwargs):
        logger.info(f"[Online Validate] Request received")
        
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        token_value = serializer.validated_data['token']
        manager = OnlineClassTokenManager()
        
        try:
            payload = manager.get_payload(token_value)
            logger.info(f"[Online Validate] Token decoded successfully")
        except Exception as e:
            logger.error(f"[Online Validate] Token decode failed - error={str(e)}")
            raise

        course_id = payload.get('course_id')
        user_id = payload.get('user_id')
        if not course_id or not user_id:
            logger.warning(f"[Online Validate] Invalid token payload - course_id={course_id} user_id={user_id}")
            raise AppAPIException({'message': 'Token payload is invalid.'}, status_code=status.HTTP_400_BAD_REQUEST)
        
        logger.info(f"[Online Validate] Processing for user_id={user_id} course_id={course_id}")

        detail_view = CourseDetailAPIView()
        queryset = detail_view.get_queryset()
        course = get_object_or_404(queryset, pk=course_id)
        user = get_object_or_404(UserModel.objects.all(), pk=user_id)

        logger.info(f"[Online Validate] Course found - slug={course.slug} is_online={course.is_online}")

        course_data = CourseDetailSerializer(course, context={'request': request}).data
        user_data = UserProfileSerializer(user, context={'request': request}).data
        metadata = self._build_metadata(course, payload, user=user)

        logger.info(f"[Online Validate] Success - user_id={user_id} course={course.slug} can_create={metadata.get('can_create_live_session')} can_join={metadata.get('can_join_live_session')}")

        return Response({
            'course': course_data,
            'user': user_data,
            'metadata': metadata,
        }, status=status.HTTP_200_OK)

    def _build_metadata(self, course: Course, payload: dict, user=None) -> dict:
        status_value = course.status
        has_started = status_value in [Course.StatusChoices.ONGOING, Course.StatusChoices.FINISHED]
        timing_data = course.timing if isinstance(course.timing, dict) else {}

        user = user or UserModel.objects.filter(pk=payload.get('user_id')).first()
        user_id = getattr(user, 'id', None)
        can_manage = bool(user and user.can_manage_course(course))

        live_context = self._build_live_session_context(course)
        can_join_live_session = live_context['is_online'] and self._user_can_join_live_session(user, course)
        
        logger.debug(f"[Online Validate Metadata] user_id={user_id} course={course.slug} can_manage={can_manage} is_online={live_context['is_online']} can_join={can_join_live_session}")

        metadata = {
            'status': status_value,
            'has_started': has_started,
            'has_finished': status_value == Course.StatusChoices.FINISHED,
            'professor_in_class': payload.get('extra', {}).get('professor_in_class', False),
            'can_create_live_session': can_manage and not live_context['is_online'],
            'can_join_live_session': can_join_live_session,
            'scheduled_times': timing_data,
            'generated_at': payload.get('generated_at'),
            'validated_at': timezone.now().isoformat(),
            'redirect_path': payload.get('redirect_path'),
        }

        metadata.update(live_context)
        return metadata

    def _build_live_session_context(self, course: Course) -> dict:
        latest_session = (
            CourseLiveSession.objects.filter(course=course)
            .order_by('-started_at', '-id')
            .first()
        )

        if not latest_session:
            return {
                'is_online': False,
                'live_session': None,
                'active_room_id': None,
                'livesession_started_at': None,
                'livesession_ended_at': None,
            }

        started_at = latest_session.started_at
        ended_at = latest_session.ended_at
        is_online = bool(started_at and not ended_at)

        live_session_data = {
            'id': latest_session.id,
            'room_id': latest_session.room_id,
            'subject': latest_session.subject,
            'started_at': self._format_datetime(started_at),
            'ended_at': self._format_datetime(ended_at),
        }

        return {
            'is_online': is_online,
            'live_session': live_session_data,
            'active_room_id': live_session_data['room_id'] if is_online and live_session_data['room_id'] else None,
            'livesession_started_at': live_session_data['started_at'],
            'livesession_ended_at': live_session_data['ended_at'],
        }

    @staticmethod
    def _user_can_join_live_session(user, course: Course) -> bool:
        if not user:
            return False
        if user.can_manage_course(course):
            return True
        return Participant.objects.filter(course=course, student_id=user.id, is_active=True).exists()

    @staticmethod
    def _format_datetime(value):
        if not value:
            return None
        if isinstance(value, str):
            return value
        if timezone.is_naive(value):
            value = timezone.make_aware(value, timezone.get_current_timezone())
        return timezone.localtime(value).isoformat()

    # DEPRECATED: This polling approach is inefficient and has been replaced by webhook integration
    # def _sync_room_status_with_plugnmeet(self, course: Course):
    #     """
    #     Check if active live session's room is still active in PlugNMeet.
    #     If room is inactive, close the session and all related user entries.
    #     
    #     DEPRECATED: This should be replaced by webhook integration.
    #     PlugNMeet now sends webhooks when rooms end, eliminating the need for polling.
    #     """
    #     active_session = CourseLiveSession.objects.filter(
    #         course=course,
    #         ended_at__isnull=True
    #     ).first()
    #
    #     if not active_session or not active_session.room_id:
    #         return
    #
    #     try:
    #         client = PlugNMeetClient()
    #         response = client.is_room_active(active_session.room_id)
    #         is_active = response.get('isActive', False)
    #
    #         if not is_active:
    #             logger.info(f"[Room Sync] Room inactive in PlugNMeet - room_id={active_session.room_id} session_id={active_session.id}")
    #             self._close_live_session(active_session)
    #         else:
    #             logger.debug(f"[Room Sync] Room still active - room_id={active_session.room_id} session_id={active_session.id}")
    #     
    #     except (PlugNMeetError, Exception) as e:
    #         logger.warning(f"[Room Sync] Failed to check room status - room_id={active_session.room_id} error={str(e)}")

    @staticmethod
    def _close_live_session(session: CourseLiveSession):
        """
        Close a live session and all related user entries.
        Sets ended_at for session and exited_at/is_online for users.
        """
        now = timezone.now()
        
        session.ended_at = now
        session.save(update_fields=['ended_at', 'updated_at'])
        logger.info(f"[Room Sync] Session closed - session_id={session.id} room_id={session.room_id} ended_at={now}")

        updated_count = LiveSessionUser.objects.filter(
            session=session,
            is_online=True,
            exited_at__isnull=True
        ).update(
            is_online=False,
            exited_at=now,
            updated_at=now
        )
        
        if updated_count > 0:
            logger.info(f"[Room Sync] User sessions closed - session_id={session.id} count={updated_count}")