from django.db.models import Q
from rest_framework import viewsets
from rest_framework.permissions import IsAuthenticated, IsAdminUser
from rest_framework.authentication import TokenAuthentication
from apps.course.models import (
    Course,
    CourseChapter,
    CourseLesson,
    CourseAttachment,
    CourseGlossary
)
from apps.course.serializers.admin import (
    AdminCourseListSerializer,
    AdminCourseDetailSerializer,
    AdminCourseChapterSerializer,
    AdminCourseLessonSerializer,
    AdminCourseAttachmentSerializer,
    AdminCourseGlossarySerializer
)

class AdminCourseViewSet(viewsets.ModelViewSet):
    """
    Admin CRUD ViewSet for Course management.
    """
    permission_classes = [IsAuthenticated, IsAdminUser]
    authentication_classes = [TokenAuthentication]

    def get_serializer_class(self):
        if self.action == 'list':
            return AdminCourseListSerializer
        return AdminCourseDetailSerializer

    def get_queryset(self):
        queryset = Course.objects.all().select_related('category', 'professor')

        # Search Query
        search_query = self.request.query_params.get('search', None)
        if search_query:
            queryset = queryset.filter(
                Q(title__icontains=search_query) |
                Q(description__icontains=search_query) |
                Q(short_description__icontains=search_query)
            )

        # Filters
        category_id = self.request.query_params.get('category', None)
        if category_id:
            queryset = queryset.filter(category_id=category_id)

        level = self.request.query_params.get('level', None)
        if level:
            queryset = queryset.filter(level=level)

        status_param = self.request.query_params.get('status', None)
        if status_param:
            queryset = queryset.filter(status=status_param)

        is_free_param = self.request.query_params.get('is_free', None)
        if is_free_param is not None:
            if is_free_param.lower() == 'true':
                queryset = queryset.filter(is_free=True)
            elif is_free_param.lower() == 'false':
                queryset = queryset.filter(is_free=False)

        return queryset.order_by('-id')


class AdminChapterViewSet(viewsets.ModelViewSet):
    """
    Admin CRUD ViewSet for Course Chapters.
    """
    permission_classes = [IsAuthenticated, IsAdminUser]
    authentication_classes = [TokenAuthentication]
    serializer_class = AdminCourseChapterSerializer
    pagination_class = None

    def get_queryset(self):
        queryset = CourseChapter.objects.all()
        course_id = self.request.query_params.get('course', None)
        if course_id:
            queryset = queryset.filter(course_id=course_id)
        return queryset.order_by('priority', 'id')


class AdminCourseLessonViewSet(viewsets.ModelViewSet):
    """
    Admin CRUD ViewSet for Lessons associated with a Course/Chapter.
    """
    permission_classes = [IsAuthenticated, IsAdminUser]
    authentication_classes = [TokenAuthentication]
    serializer_class = AdminCourseLessonSerializer
    pagination_class = None

    def get_queryset(self):
        queryset = CourseLesson.objects.all().select_related('lesson', 'chapter')
        
        course_id = self.request.query_params.get('course', None)
        if course_id:
            queryset = queryset.filter(course_id=course_id)

        chapter_id = self.request.query_params.get('chapter', None)
        if chapter_id:
            queryset = queryset.filter(chapter_id=chapter_id)

        return queryset.order_by('priority', 'id')

    def perform_destroy(self, instance):
        # Prevent orphans: delete the base Lesson object along with the junction model
        lesson = instance.lesson
        instance.delete()
        if lesson:
            lesson.delete()


class AdminCourseAttachmentViewSet(viewsets.ModelViewSet):
    """
    Admin CRUD ViewSet for Course Attachments.
    """
    permission_classes = [IsAuthenticated, IsAdminUser]
    authentication_classes = [TokenAuthentication]
    serializer_class = AdminCourseAttachmentSerializer
    pagination_class = None

    def get_queryset(self):
        queryset = CourseAttachment.objects.all().select_related('attachment')
        course_id = self.request.query_params.get('course', None)
        if course_id:
            queryset = queryset.filter(course_id=course_id)
        return queryset.order_by('-id')

    def perform_destroy(self, instance):
        # Prevent orphans: delete base Attachment along with junction model
        attachment = instance.attachment
        instance.delete()
        if attachment:
            attachment.delete()


class AdminCourseGlossaryViewSet(viewsets.ModelViewSet):
    """
    Admin CRUD ViewSet for Course Glossary terms.
    """
    permission_classes = [IsAuthenticated, IsAdminUser]
    authentication_classes = [TokenAuthentication]
    serializer_class = AdminCourseGlossarySerializer
    pagination_class = None

    def get_queryset(self):
        queryset = CourseGlossary.objects.all().select_related('glossary')
        course_id = self.request.query_params.get('course', None)
        if course_id:
            queryset = queryset.filter(course_id=course_id)
        return queryset.order_by('-id')

    def perform_destroy(self, instance):
        # Prevent orphans: delete base Glossary along with junction model
        glossary = instance.glossary
        instance.delete()
        if glossary:
            glossary.delete()