from django.db import models
from django.db.models import F
from django.utils.translation import gettext_lazy as _

from university.db.fields import JSONField
from university.lectures.managers import lecture_manager
from university.models.user_lesson_learn_history import UserLessonLearnHistory
from university.models.user_quiz import UserQuiz
from university.models.quiz import Quiz


class Lesson(models.Model):

    slug = models.SlugField(blank=False, null=False, allow_unicode=True)
    title = models.CharField(max_length=128)
    description = models.TextField()
    # At first release, wo don't need teacher(Model)
    speaker = models.CharField(max_length=64)
    sequence = models.SmallIntegerField(
        default=0,
        help_text=_('lessons will be orderd by sequence number in list')
    )
    periods = models.FloatField(default=1)
    chapter = models.ForeignKey('university.Chapter', on_delete=models.PROTECT)
    cover_image = models.ForeignKey(
        'university.Upload', on_delete=models.PROTECT, blank=True, null=True)
    objectives = models.TextField()
    key_points = models.CharField(max_length=255, blank=True, null=True)
    markdown_raw = models.TextField()
    pdf = models.ForeignKey(
        'university.Upload', related_name='pdf', on_delete=models.PROTECT, blank=True, null=True)
    is_free = models.BooleanField(default=False)
    types = JSONField(default=[])

    class Meta:
        db_table = 'lessons'

    def __str__(self):
        return self.title

    @property
    def short_title(self):
        return '{} - {}.{}'.format(
            self.chapter.course.slug,
            self.chapter.sequence,
            self.sequence)

    def get_syllabus(self, user):
        data = {}
        for tp in self.types:
            install_lectures = lecture_manager.install_lectures
            lecture = install_lectures.get(tp)
            if lecture:
                data[tp] = lecture.description(self, user)
        return data

    def has_quiz(self):
        try:
            return bool(self.quiz)
        except Quiz.DoesNotExist:
            return False

    def get_quiz(self, user):
        # Raise lesson.RelatedObjectDoesNotExist if quiz not exsits
        is_passed = False

        questions = self.quiz.questions.values(
            'id', 'question_type', 'problem', 'problem', 'options', 'answer')

        try:
            user_quiz = user.userquiz_set.get(quiz=self.quiz)
            is_passed = user_quiz.is_passed
            for question in questions:
                if not is_passed:
                    question['answer'] = user_quiz.answer.get(str(question['id']), '')
        # AnonymousUser -> AttributeError
        # user_quiz not exists -> UserQuiz.DoesNotExist
        except (UserQuiz.DoesNotExist, AttributeError):
            for question in questions:
                question['answer'] = ''
        return list(questions), is_passed

    @classmethod
    def update_lesson_progress(cls, lesson_id, user_id):
        try:
            lesson = cls.objects.get(pk=lesson_id)
        except cls.DoesNotExist:
            return

        lecture_progress = []

        for tp in lesson.types:
            lecture = lecture_manager.install_lectures.get(tp)
            if lecture:
                lecture_progress.append(lecture.get_progress(lesson_id, user_id))

        lesson_progress = sum(map(lambda p: p / len(lecture_progress), lecture_progress))

        lesson_progress = 1 if lesson_progress > 0.98 else lesson_progress

        history, _ = UserLessonLearnHistory.objects.get_or_create(
            course=lesson.chapter.course,
            chapter=lesson.chapter,
            lesson=lesson,
            user_id=user_id)
        UserLessonLearnHistory.objects.filter(pk=history.id).update(
            progress=lesson_progress if lesson_progress > history.progress else history.progress,
            total_visited_count=F('total_visited_count') + 1)