from rest_framework.exceptions import NotFound

from university.api.base import Endpoint
from university.models import Lesson


class LessonEndpoint(Endpoint):

    def convert_args(self, request, course_slug, chapter_slug, lesson_slug, *args, **kwargs):
        try:
            lesson = Lesson.objects.select_related('chapter', 'chapter__course').get(
                slug=lesson_slug,
                chapter__slug=chapter_slug,
                chapter__course__slug=course_slug)
            chapter = lesson.chapter
            course = chapter.course
        except Lesson.DoesNotExist:
            raise NotFound

        if not (course.visable_when_no_perm or request.user.has_course(course)):
            raise NotFound

        kwargs['course'] = course
        kwargs['chapter'] = chapter
        kwargs['lesson'] = lesson
        return (args, kwargs)