from rest_framework import serializers

from dj_filer.admin import get_thumbs

from apps.course.models import Course, CourseCategory, Attachment, Glossary, LessonCompletion, Participant, Lesson
from apps.chat.models import RoomMessage
from apps.account.serializers import UserProfileSerializer



class CourseCategorySerializer(serializers.ModelSerializer):
    course_count = serializers.SerializerMethodField()
    
    class Meta:
        model = CourseCategory
        fields = ['name', 'slug', 'course_count'] 

    def get_course_count(self, obj):
        return obj.course_count


class CourseListSerializer(serializers.ModelSerializer):
    category = CourseCategorySerializer()
    thumbnail = serializers.SerializerMethodField()
    participant_count = serializers.SerializerMethodField()
    lessons_count = serializers.SerializerMethodField()
    
    class Meta:
        model = Course        
        fields = [
            'id',
            'title',
            'slug',
            'participant_count',
            'category',
            'thumbnail',
            'is_online',
            'level',
            'duration',
            'lessons_count',
            'short_description',
            'status',
            'is_free',
            'price',
            'discount_percentage',
            'final_price',    
        ]

    def get_thumbnail(self, obj):
        return get_thumbs(obj.thumbnail, self.context.get('request'))
    
    def get_participant_count(self, obj):
        return obj.participants.count()
    
    def get_lessons_count(self, obj):
        lessons_count = obj.lessons.filter(is_active=True).count()
        return max(lessons_count, obj.lessons_count)

        
        
    
    
class CourseDetailSerializer(serializers.ModelSerializer):
    category = CourseCategorySerializer()
    professor = UserProfileSerializer()
    thumbnail = serializers.SerializerMethodField()
    participant_count = serializers.SerializerMethodField()
    access = serializers.SerializerMethodField()
    lessons_complated_count = serializers.SerializerMethodField()
    lessons_count = serializers.SerializerMethodField()
    last_lesson_id = serializers.SerializerMethodField()
    room_id = serializers.SerializerMethodField()  
    
    class Meta:
        model = Course        
        fields = [
            'id',
            'title',
            'slug',
            'category',
            'access',
            'participant_count',
            'professor',
            'thumbnail',
            'video_type',
            'video_file',
            'video_link',
            'is_online',
            'level',
            'description',
            'duration',
            'lessons_count',
            'lessons_complated_count',
            'short_description',
            'status',
            'is_free',
            'price',
            'discount_percentage',
            'final_price',
            'timing',
            'features',
            'last_lesson_id',
            'room_id'
        ]

    def get_room_id(self, obj):
        room_message = RoomMessage.objects.filter(course=obj).first()
        if room_message:
            return room_message.id
        return None
    
    def get_last_lesson_id(self, obj):
        request = self.context.get('request')
        if request and request.user.is_authenticated:
            user = request.user
            
            # آخرین درس تکمیل‌شده توسط کاربر
            last_completed_lesson = LessonCompletion.objects.filter(
                student=user,
                lesson__course=obj
            ).order_by('-completed_at').first()
            
            if last_completed_lesson:
                # پیدا کردن درس بعدی بر اساس priority
                next_lesson = Lesson.objects.filter(
                    course=obj,
                    priority__gt=last_completed_lesson.lesson.priority,
                    is_active=True
                ).order_by('priority').first()
                if not next_lesson:
                    next_lesson = Lesson.objects.filter(
                        course=obj,
                        is_active=True
                    ).order_by('priority').first()
                if next_lesson:
                    return next_lesson.id    
        return None
            
            
            
    def get_access(self, obj):
        if student := self._get_authenticated_user():
            if not self._is_participant(student, obj):
                return False
            return True            
        return False
            
    def get_is_professor(self, obj):
        if professor := self._get_authenticated_user():
            return obj.professor == professor
        return False
        
    def get_lessons_count(self, obj):
        lessons_count = obj.lessons.filter(is_active=True).count()
        return max(lessons_count, obj.lessons_count)


    def get_lessons_complated_count(self, obj):
        if student := self._get_authenticated_user():
            if not self._is_participant(student, obj):
                return None
            return self._get_completed_lessons_count(student, obj)        
        return None
        
    def _is_participant(self, student, course):
        """Helper method to check if a student is a participant in the given course."""
        return Participant.objects.filter(student=student, course=course).exists()

    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_completed_lessons_count(self, student, course):
        """Helper method to count completed lessons for the student in the given course."""
        return LessonCompletion.objects.filter(
            student=student,
            lesson__course=course
        ).count()
        

    def get_thumbnail(self, obj):
        return get_thumbs(obj.thumbnail, self.context.get('request'))
    
    def get_participant_count(self, obj):
        return obj.participants.count()

    
    
class MyCourseListSerializer(serializers.ModelSerializer):
    category = CourseCategorySerializer()
    thumbnail = serializers.SerializerMethodField()
    lessons_complated_count = serializers.SerializerMethodField()

    class Meta:
        model = Course        
        fields = [
            'id',
            'title',
            'slug',
            'category',
            'thumbnail',
            'lessons_count',
            'lessons_complated_count',
            'short_description',
            'status',
        ]

    def get_thumbnail(self, obj):
        return get_thumbs(obj.thumbnail, self.context.get('request'))
    
    def get_lessons_complated_count(self, obj):
        if student := self._get_authenticated_user():
            if not self._is_participant(student, obj):
                return None
            return self._get_completed_lessons_count(student, obj)        
        return None
        
    def _is_participant(self, student, course):
        """Helper method to check if a student is a participant in the given course."""
        return Participant.objects.filter(student=student, course=course).exists()

    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_completed_lessons_count(self, student, course):
        """Helper method to count completed lessons for the student in the given course."""
        return LessonCompletion.objects.filter(
            student=student,
            lesson__course=course
        ).count()
    

class AttachmentSerializer(serializers.ModelSerializer):
    class Meta:
        model = Attachment
        fields = ['id', 'title', 'file', 'file_size']
        

class GlossarySerializer(serializers.ModelSerializer):
    class Meta:
        model = Glossary
        fields = ['id', 'title', 'description']