bookwyrm/bookwyrm/models/base_model.py

""" base model with default fields """
from django.db import models
from django.dispatch import receiver

from bookwyrm.settings import DOMAIN
from .fields import RemoteIdField


class BookWyrmModel(models.Model):
    """shared fields"""

    created_date = models.DateTimeField(auto_now_add=True)
    updated_date = models.DateTimeField(auto_now=True)
    remote_id = RemoteIdField(null=True, activitypub_field="id")

    def get_remote_id(self):
        """generate a url that resolves to the local object"""
        base_path = "https://%s" % DOMAIN
        if hasattr(self, "user"):
            base_path = "%s%s" % (base_path, self.user.local_path)
        model_name = type(self).__name__.lower()
        return "%s/%s/%d" % (base_path, model_name, self.id)

    class Meta:
        """this is just here to provide default fields for other models"""

        abstract = True

    @property
    def local_path(self):
        """how to link to this object in the local app"""
        return self.get_remote_id().replace("https://%s" % DOMAIN, "")

    def visible_to_user(self, viewer):
        """is a user authorized to view an object?"""
        # make sure this is an object with privacy owned by a user
        if not hasattr(self, "user") or not hasattr(self, "privacy"):
            return None

        # viewer can't see it if the object's owner blocked them
        if viewer in self.user.blocks.all():
            return False

        # you can see your own posts and any public or unlisted posts
        if viewer == self.user or self.privacy in ["public", "unlisted"]:
            return True

        # you can see the followers only posts of people you follow
        if (
            self.privacy == "followers"
            and self.user.followers.filter(id=viewer.id).first()
        ):
            return True

        # you can see dms you are tagged in
        if hasattr(self, "mention_users"):
            if (
                self.privacy == "direct"
                and self.mention_users.filter(id=viewer.id).first()
            ):
                return True
        return False


@receiver(models.signals.post_save)
# pylint: disable=unused-argument
def set_remote_id(sender, instance, created, *args, **kwargs):
    """set the remote_id after save (when the id is available)"""
    if not created or not hasattr(instance, "get_remote_id"):
        return
    if not instance.remote_id:
        instance.remote_id = instance.get_remote_id()
        try:
            instance.save(broadcast=False)
        except TypeError:
            instance.save()