from rest_framework import serializers
from apps.course.models import Lesson, CourseLesson, Participant, LessonCompletion
from apps.course.access import user_has_course_access
from apps.quiz.serializers import QuizListSerializer
from apps.course.models.course import get_localized_field


class LessonSerializer(serializers.ModelSerializer):
    title = serializers.SerializerMethodField()
    content_type = serializers.SerializerMethodField()

    class Meta:
        model = Lesson
        fields = ['id', 'title', 'content_type', 'content_file', 'video_link', 'duration']

    def _lang(self):
        request = self.context.get('request')
        return getattr(request, 'LANGUAGE_CODE', None) or 'en'

    def get_title(self, obj):
        return get_localized_field(self._lang(), obj.title)

    def get_content_type(self, obj):
        return get_localized_field(self._lang(), obj.content_type)


class CourseLessonSerializer(serializers.ModelSerializer):
    is_active = serializers.SerializerMethodField()
    is_complated = serializers.SerializerMethodField()
    quizs = serializers.SerializerMethodField()    
    permission = serializers.SerializerMethodField()
    title = serializers.SerializerMethodField()
    content_type = serializers.SerializerMethodField()
    content_file = serializers.FileField(source='lesson.content_file', read_only=True)
    video_link = serializers.CharField(source='lesson.video_link', read_only=True)
    duration = serializers.IntegerField(source='lesson.duration', read_only=True)
    
    class Meta:
        model = CourseLesson
        fields = ['id', 'title', 'priority', 'is_active', 'permission', 'duration', 'content_type', 'content_file', 'video_link', 'is_complated', 'quizs']

    def _lang(self):
        request = self.context.get('request')
        return getattr(request, 'LANGUAGE_CODE', None) or 'en'

    def get_title(self, obj):
        return get_localized_field(self._lang(), obj.title)

    def get_content_type(self, obj):
        return get_localized_field(self._lang(), obj.lesson.content_type)

    def get_is_active(self, obj):
        return obj.is_active and self._has_access_for_object(obj)
        
    def get_permission(self, obj):
        return self._has_access_for_object(obj)

    def _has_access_for_object(self, obj):
        if user := self._get_authenticated_user():
            return self._has_access(user, obj.course)
        return False
    
    def _has_access(self, user, course):
        return user_has_course_access(user, course)

    def _is_participant(self, student, course):
        """Deprecated: use _has_access instead."""
        return self._has_access(student, course)

    def _get_authenticated_user(self):
        """Helper method to retrieve the authenticated user from the context."""
        request = self.context.get('request')
        return request.user if request and request.user.is_authenticated else None

    def get_is_complated(self, obj):
        request = self.context.get('request')
        if not request or not request.user.is_authenticated:
            return False
        user = request.user

        if not self._has_access(user, obj.course):
            return False

        # Use prefetched completions if available
        if hasattr(obj, 'completions') and obj.completions.all():
            return any(completion.student_id == user.id for completion in obj.completions.all())

        # Fallback to direct queries
        is_participant = Participant.objects.filter(
            student=user,
            course=obj.course
        ).exists()

        if not is_participant:
            return False

        return LessonCompletion.objects.filter(
            student=user,
            course_lesson=obj
        ).exists()

    def get_quizs(self, obj):
        # Now quizzes are directly related to CourseLesson
        # print(f'--> type:{type(obj)}  obj:{obj.quizzes.all()}')
        quizzes = obj.quizzes.all() if hasattr(obj, 'quizzes') else []
        if quizzes:
            return QuizListSerializer(quizzes, many=True, context=self.context).data
        return None


from apps.course.models import CourseChapter

# 👇 ADD V2 SERIALIZERS

class CourseChapterSerializer(serializers.ModelSerializer):
    """
    V2 API: Returns a Chapter and a nested list of all its active lessons
    """
    is_active = serializers.SerializerMethodField()
    lessons = serializers.SerializerMethodField()
    title = serializers.SerializerMethodField()

    class Meta:
        model = CourseChapter
        fields = ['id', 'title', 'priority', 'is_active', 'lessons']

    def _lang(self):
        request = self.context.get('request')
        return getattr(request, 'LANGUAGE_CODE', None) or 'en'

    def get_title(self, obj):
        return get_localized_field(self._lang(), obj.title)

    def get_is_active(self, obj):
        if not obj.is_active:
            return False

        request = self.context.get('request')
        if not request or not request.user.is_authenticated:
            return False

        return user_has_course_access(request.user, obj.course)

    def get_lessons(self, obj):
        # Grab all active lessons tied to this specific chapter
        chapter_lessons = obj.lessons.filter(is_active=True).order_by('priority')
        # Re-use the V1 CourseLessonSerializer to serialize the nested items
        return CourseLessonSerializer(chapter_lessons, many=True, context=self.context).data