models.py

from __future__ import annotations

from django.db import models
from django.contrib.auth.models import AbstractUser


class FollowRequest(models.Model):

    to_follow = models.ForeignKey(
        'user.User', on_delete=models.CASCADE, related_name='requests'
    )
    requester = models.ForeignKey(
        'user.User', on_delete=models.CASCADE, db_index=False, related_name='+'
    )

    def accept(self) -> None:
        self.requester.follow(self.to_follow, force=True)
        self.delete()

    def reject(self) -> None:
        self.delete()

    def __str__(self) -> str:
        return f'{self.requester} -> {self.to_follow}'


class User(AbstractUser):

    PRIVATE = True
    PUBLIC = False

    VISIBILITY_CHOICES = [
        (PRIVATE, 'Private'),
        (PUBLIC, 'Public'),
    ]

    visibility: bool = models.BooleanField(default=PUBLIC, choices=VISIBILITY_CHOICES)
    bio: str = models.CharField(
        max_length=250, null=True, blank=True, help_text='About the user.'
    )
    picture = models.ImageField(
        null=True,
        blank=True,
        default='default.png',
        upload_to='profile_pictures',
        verbose_name='profile picture',
    )

    _follows = models.ManyToManyField('User', blank=True, related_name='followed_by')

    def unfollow(self, user: User) -> None:
        """ Helper function to remove a user from this users following list. """

        self._follows.remove(user)

    def follow(self, user: User, force: bool = False) -> None:
        """ Helper function to add user to a follower list. """

        if user.id == self.id:
            return

        if force:
            self._follows.add(user)
            return

        if user.visibility == User.PRIVATE:
            FollowRequest.objects.get_or_create(requester=self, to_follow=user)
        else:
            self._follows.add(user)

    def tweet_count(self) -> int:
        return self.tweets.count()

    def follower_count(self) -> int:
        return self.followers.count()

    def following_count(self) -> int:
        return self.following.count()

    @property
    def following(self) -> models.QuerySet:
        """ Returns a QuerySet of Users that this user follows. """
        return self._follows.all()

    @property
    def followers(self) -> models.QuerySet:
        """ Returns a QuerySet of Users following this user. """
        return self.followed_by.all()