from django.contrib.auth import get_user_model
from rest_framework import serializers

from courses.models import Course, Lesson, Topic


class TopicSerializer(serializers.ModelSerializer):
    children = serializers.SerializerMethodField()

    class Meta:
        model = Topic
        fields = '__all__'

    @staticmethod
    def get_children(self):
        return [MiniLessonSerializer(i).data for i in self.lesson_set.all()]


class MiniLessonSerializer(serializers.ModelSerializer):

    class Meta:
        model = Lesson
        fields = ('title', 'free', 'token', 'is_hm')


class LessonSerializer(MiniLessonSerializer):
    course_slug = serializers.SerializerMethodField()

    class Meta:
        model = Lesson
        exclude = ('id', 'topic', 'key')

    @staticmethod
    def get_course_slug(self):
        return self.topic.course.slug


class TeacherLessonSerializer(MiniLessonSerializer):
    topic_sort = serializers.SerializerMethodField()
    topic_title = serializers.SerializerMethodField()
    course_title = serializers.SerializerMethodField()

    class Meta:
        model = Lesson
        fields = ('topic_sort', 'description', 'title', 'course_title', 'token', 'topic_title')

    @staticmethod
    def get_topic_sort(self):
        for topic_idx, topic in enumerate(self.topic.course.topic_set.all()):
            if topic == self.topic:
                return topic_idx + 1
        return None

    @staticmethod
    def get_topic_title(self):
        return self.topic.title

    @staticmethod
    def get_course_title(self):
        return self.topic.course.title


class CourseInitSerializer(serializers.ModelSerializer):

    class Meta:
        model = Course
        fields = ['title', 'slug']


class CourseTreeSerializer(serializers.ModelSerializer):
    tree = serializers.SerializerMethodField()

    class Meta:
        model = Course
        fields = ('tree', 'slug')

    @staticmethod
    def get_tree(self):
        return [TopicSerializer(i).data for i in self.topic_set.all()]


class CourseDetailSerializer(serializers.ModelSerializer):
    level = serializers.SerializerMethodField()
    direction = serializers.SerializerMethodField()
    statistic = serializers.SerializerMethodField()
    teacher_emails = serializers.SerializerMethodField()

    class Meta:
        model = Course
        exclude = ('id', )

    @staticmethod
    def get_teacher_emails(self):
        return [i.email for i in get_user_model().objects.filter(out_key__in=self.teacher_tokens)]

    @staticmethod
    def get_level(self):
        return self.get_level_display()

    @staticmethod
    def get_direction(self):
        return self.get_direction_display()

    @staticmethod
    def get_statistic(self):
        return self.get_statistic()