from jwt import DecodeError

from courses.models import Course, Lesson
from rest_framework.renderers import JSONRenderer
from rest_framework.response import Response
from rest_framework.views import APIView
from django.contrib.auth import get_user_model

from courses.serializers import CourseDetailSerializer, CourseTreeSerializer, LessonSerializer, TeacherLessonSerializer
import jwt

from courses.tasks import add_lesson
from lms import settings


class TreeView(APIView):
    renderer_classes = (JSONRenderer,)
    status_code = 200

    def get(self, request, slug):

        try:
            course = Course.objects.get(slug=slug)
            return Response(CourseTreeSerializer(course).data, self.status_code)
        except Course.DoesNotExist:
            return Response("Course doesn't exist", status=404)


class CourseListView(APIView):
    renderer_classes = (JSONRenderer,)
    status_code = 200

    def post(self, request):
        """
        This API endpoint create/update course.
        ---
        parameters:
          - name: level
            type: string
            required: true
            location: form
          - name: direction
            type: string
            required: true
            location: form
          - name: statistic
            type: string
            required: true
            location: form
            ...
        """
        # TODO: Костыль
        teachers_emails = request.JSON.get('teachers', [])
        request.JSON['teachers'] = [get_user_model().objects.get(email=i).out_key for i in teachers_emails]
        course = Course.objects.update_or_create_course(**request.JSON.dict())
        return Response(CourseDetailSerializer(course).data, status=self.status_code)

    def get(self, request):
        """
        This API endpoint return list of courses.
        ---
        """
        res = [CourseDetailSerializer(course).data for course in Course.objects.all()]
        return Response(res, self.status_code)


class CourseDetailView(APIView):
    renderer_classes = (JSONRenderer,)
    status_code = 200

    @staticmethod
    def delete(request, slug):
        try:
            Course.objects.get(slug=slug).delete()
        except Course.DoesNotExist:
            return Response("Курса не существует", status=404)
        return Response(status=204)

    def get(self, request, slug):
        return Response(CourseDetailSerializer(Course.objects.get(slug=slug)).data, self.status_code)


class LessonInfoView(APIView):
    renderer_classes = (JSONRenderer,)
    status_code = 200

    def get(self, request, token):
        try:
            lesson = Lesson.objects.get(token=token)
        except Lesson.DoesNotExist:
            return Response('Урок не найден', status=404)
        if request.user.is_authenticated and request.user.out_key in lesson.topic.course.teacher_tokens:
            return Response(TeacherLessonSerializer(lesson).data, self.status_code)
        return Response("Пользователь не является преподователем по курсу", status=403)


class LessonDetail(APIView):
    renderer_classes = (JSONRenderer,)

    @staticmethod
    def post(request, token):
        jwt_token = request.JSON.get('jwt_token', None)

        try:
            lesson = Lesson.objects.get(token=token)
        except Lesson.DoesNotExist:
            return Response("Урока не существует", status=404)

        l = LessonSerializer(lesson).data

        try:
            payload = None if jwt_token is None\
                else jwt.decode(jwt_token, settings.COURSE_PROGRESS_SECRET_KEY, algorithms=['HS256'])
        except DecodeError:
            payload = None

        course = lesson.topic.course

        if payload is None:
            if not lesson.free:
                return Response("Bad token", status=400)

            else:
                return Response(l, status=200)

        prev_lesson = course.get_previous(lesson, (lambda x: not x.is_hm) if payload['only_watch'] else None)
        next_lesson = course.get_next(lesson, (lambda x: not x.is_hm) if payload['only_watch'] else None)

        if not prev_lesson is None:
            l['prev_token'] = prev_lesson.token

        if not next_lesson is None:
            l['next_token'] = next_lesson.token

        new_lesson = False
        for payload_lesson in payload['lessons']:
            if payload_lesson['lesson_token'] == str(lesson.token):
                return Response(l, status=200)

            if not prev_lesson is None and str(prev_lesson.token) == payload_lesson['lesson_token']:
                new_lesson = True if prev_lesson is None else \
                    (payload_lesson['status'] == "done" or payload_lesson['status'] == "wait")

        if not new_lesson:
            return Response("Permission denied", status=403)

        #TODO Задача для селери
        add_lesson(request.user.out_key, course.token, lesson.token, course.get_teacher(), lesson.is_hm)

        return Response(l, status=200)