from rest_framework import serializers
import json
# from django.contrib.auth import get_user_model
# from django.core.exceptions import ObjectDoesNotExist

from courses.models import Course, Vertex, Tutorial, Topic, Task


class TutorialSerializer(serializers.ModelSerializer):
    class Meta:
        model = Tutorial
        exclude = ['id']


class TaskSerializer(serializers.ModelSerializer):
    class Meta:
        model = Task
        exclude = ['id']


class TopicSerializer(serializers.ModelSerializer):
    class Meta:
        model = Topic
        exclude = ['id']


class MiniVertexSerializer(serializers.ModelSerializer):
    object = serializers.SerializerMethodField()
    type = serializers.SerializerMethodField()
    children = serializers.SerializerMethodField()

    class Meta:
        model = Vertex
        fields = ('id', 'title', 'type', 'object', 'children')

    @staticmethod
    def get_object(self):
        if self.content_type.model == 'tutorial':
            return TutorialSerializer(self.content_object).data

        elif self.content_type.model == 'topic':
            return TopicSerializer(self.content_object).data

        elif self.content_type.model == 'task':
            return TaskSerializer(self.content_object).data

    @staticmethod
    def get_type(self):
        return self.content_type.model

    @staticmethod
    def get_children(self):
        return json.loads(self.sort_map.dependent_elements)


class VertexSerializer(MiniVertexSerializer):
    class Meta:
        model = Vertex
        fields = ('id', 'title', 'type', 'object', 'children', 'description')

    @staticmethod
    def get_children(self):
        return [VertexSerializer(Vertex.manager.get(id=i)).data
                for i in json.loads(self.sort_map.dependent_elements)]


class CourseListSerializer(serializers.ModelSerializer):
    length = serializers.SerializerMethodField()
    level = serializers.SerializerMethodField()
    direction = serializers.SerializerMethodField()

    class Meta:
        model = Course
        fields = ['id', 'title', 'length',
                  'level', 'direction', 'image', ]

    @staticmethod
    def get_length(self):
        return 15

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

    @staticmethod
    def get_direction(self):
        return self.direction.title


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

    class Meta:
        model = Course
        fields = ['id', 'children']

    @staticmethod
    def get_children(self):
        return [MiniVertexSerializer(Vertex.manager.get(id=i)).data
                for i in json.loads(self.sort_map.dependent_elements)]


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

    class Meta:
        model = Course
        exclude = (
            'slug', 'mentors', 'page', 'sort',
            'preview', 'use_fail', 'basic_len',
            'addition_len', 'min_price', 'buy_icon',
            'must_build', 'keywords', 'recommend',
        )

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

    @staticmethod
    def get_direction(self):
        return self.direction.title

    @staticmethod
    def get_teachers(self):
        return [teacher.full_name() for teacher in self.teachers.all()]