from django.contrib.auth import get_user_model
from django.db import models
from django.db.models import CASCADE
from django.urls import reverse

User = get_user_model()


class StoryRound(models.Model):
    name = models.CharField(max_length=256)
    participants = models.ManyToManyField(User)  # for ordering add: through='Participant'
    created = models.DateTimeField(auto_now_add=True)
    number_of_rounds = models.IntegerField()

    def get_absolute_url(self):
        return reverse('writing:detail', kwargs={'pk': self.pk})

    def get_next_story_part(self, user: User) -> 'StoryPart':
        # TODO: implement, for each story get unfinished part and check user
        pass


class Participant(models.Model):
    user = models.ForeignKey(User, on_delete=CASCADE)
    story_round = models.ForeignKey(StoryRound, on_delete=CASCADE)
    order_by = models.IntegerField()


class Story(models.Model):
    name = models.CharField(max_length=256, null=True, blank=True)
    created = models.DateTimeField(auto_now_add=True)
    part_of_round = models.ForeignKey(StoryRound, on_delete=CASCADE)
    started_by = models.ForeignKey(User, on_delete=CASCADE)
    finished = models.BooleanField(default=False)

    def get_first_unfinished_part(self):
        if self.finished:
            return None

        first_part = StoryPart.objects.get(part_of_id=self.pk, previous_part__isnull=True)

        last_unfinished_part = first_part
        while last_unfinished_part.finished:
            last_unfinished_part = StoryPart.objects.get(previous_part=last_unfinished_part)

        return last_unfinished_part


class StoryPart(models.Model):
    user = models.ForeignKey(User, on_delete=CASCADE)
    previous_part = models.ForeignKey('StoryPart', on_delete=CASCADE, null=True, blank=True)
    text = models.TextField(null=True, blank=True)
    part_of = models.ForeignKey('Story', on_delete=CASCADE)

    @property
    def finished(self):
        return self.text