from django.conf import settings
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


from apps.course.serializers import (
    CourseListSerializer, CourseCategorySerializer, CourseDetailSerializer,
    CourseAttachmentSerializer, CourseGlossarySerializer, MyCourseListSerializer,
    OnlineClassTokenCreateSerializer, OnlineClassTokenVerifySerializer
)
from apps.course.models import Course, CourseCategory, CourseAttachment, CourseGlossary, Participant
from apps.course.doc import *
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(),
    )
    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(
    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 super().get(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"

    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(),
    )
    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",

    )
    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(
        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']
    
    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(
        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": "<temporary-token>",
                        "url": "https://frontend.example.com?token=<temporary-token>",
                        "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,
            'extra': {
                'professor_in_class': False,
            },
        })

        redirect_path = serializer.validated_data.get('redirect_path')
        base_url = self._build_base_url(redirect_path)
        entry_url = manager.build_entry_url(token, base_url=base_url)

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

    def _build_base_url(self, redirect_path=None) -> str:
        domain = getattr(settings, 'ONLINE_CLASS_FRONTEND_DOMAIN', getattr(settings, 'SITE_DOMAIN', '')).rstrip('/')
        if redirect_path:
            sanitized = redirect_path.strip('/')
            return f"{domain}/{sanitized}" if domain else f"/{sanitized}"
        return domain

    @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

    @swagger_auto_schema(
        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):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        token_value = serializer.validated_data['token']
        manager = OnlineClassTokenManager()
        payload = manager.get_payload(token_value)

        course_id = payload.get('course_id')
        user_id = payload.get('user_id')
        if not course_id or not user_id:
            raise AppAPIException({'message': 'Token payload is invalid.'}, status_code=status.HTTP_400_BAD_REQUEST)

        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)

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

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

    def _build_metadata(self, course: Course, payload: dict) -> 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 {}
        return {
            'status': status_value,
            'is_online': course.is_online,
            'has_started': has_started,
            'has_finished': status_value == Course.StatusChoices.FINISHED,
            'professor_in_class': payload.get('extra', {}).get('professor_in_class', False),
            'scheduled_times': timing_data,
            'generated_at': payload.get('generated_at'),
            'validated_at': timezone.now().isoformat(),
        }