from django.db.models import Q
from django.utils.translation import gettext as _
from django.urls import reverse

from rest_framework.response import Response
from rest_framework.permissions import AllowAny

from university.api.base import Endpoint
from university.api.bases.course import CourseEndpoint
from university.models import Course


class CourseListEndpoint(Endpoint):

    permission_classes = (AllowAny, )

    def get(self, request, *args, **kwargs):
        if request.user.is_authenticated:
            courses = Course.objects.select_related('category').filter(
                Q(groupcourse__group__user=request.user) |
                Q(usercourse__user=request.user) |
                Q(license=Course.LICENSE_FREE) |
                Q(visable_when_no_perm=True))
        else:
            courses = Course.objects.select_related('category').filter(
                Q(license=Course.LICENSE_FREE) |
                Q(visable_when_no_perm=True))

        request_categories = request.GET.get('categories', '')
        if request.GET.get('categories'):
            courses = courses.filter(category__slug__in=request_categories.split(','))
        courses = courses.distinct()

        return Response({
            'detail': _('success'),
            'datas': [{
                'title': c.title,
                'slug': c.slug,
                'cover_url': c.cover_image.url if c.cover_image else None,
                'license': c.license,
                'category': {
                    'name': c.category.name,
                    'slug': c.category.slug
                } if c.category else None
            } for c in courses]
        })


class CourseDetailEndpoint(CourseEndpoint):

    permission_classes = (AllowAny, )

    def get(self, request, course, *args, **kwargs):
        return Response({
            'detail': _('success'),
            'datas': {
                'slug': course.slug,
                'title': course.title,
                'description': course.description,
                'objectives': course.objectives,
                'propaedeutics': course.propaedeutics,
                'references': course.references,
                'license': course.license,
                'cover_url': course.cover_image.url if course.cover_image else None,
                'catalog_url': reverse('api:course-catalog', kwargs={
                    'course_slug': course.slug
                })
            }
        })
        return Response({'detail': _('success')})


class CourseCatalogEndpoint(CourseEndpoint):

    permission_classes = (AllowAny, )

    def get(self, request, course, *args, **kwargs):
        has_course = request.user.has_course(course)
        catalog = {
            'slug': course.slug,
            'title': course.title,
            'number_of_students': course.userlessonlearnhistory_set.values('user').distinct().count(),
            'speakers': course.speakers,
            'description': course.description,
            'objectives': course.objectives,
            'propaedeutics': course.propaedeutics,
            'references': course.references,
            'license': course.license,
            'cover_url': course.cover_image.url if course.cover_image else None,
            'chapters': [],
            'has_online_exam': bool(course.online_exam)
        }

        for chapter in course.chapter_set.all().order_by('sequence'):
            lessons = [{
                'slug': lesson.slug,
                'title': lesson.title,
                'periods': lesson.periods,
                'cover_url': lesson.cover_image.url if lesson.cover_image else None,
                'has_permission': has_course or lesson.is_free,
                'types': lesson.types,
                'quiz': {
                    'is_passed': request.user.is_passed_quiz(lesson)
                } if lesson.has_quiz() else None
            } for lesson in chapter.lesson_set.all().order_by('sequence')]
            catalog['chapters'].append({
                'slug': chapter.slug,
                'title': chapter.title,
                'description': chapter.description,
                'number_of_lessons': len(lessons),
                'periods': sum(l['periods'] for l in lessons),
                'lessons': lessons
            })

        return Response({'detail': _('success'), 'datas': catalog})