bookwyrm/bookwyrm/models/fields.py

''' activitypub-aware django model fields '''
import re
from uuid import uuid4

from django.contrib.auth.models import AbstractUser
from django.core.exceptions import ValidationError
from django.core.files.base import ContentFile
from django.db import models
from django.utils.translation import gettext_lazy as _
from bookwyrm import activitypub
from bookwyrm.settings import DOMAIN
from bookwyrm.connectors import get_image


def validate_remote_id(value):
    ''' make sure the remote_id looks like a url '''
    if not re.match(r'^http.?:\/\/[^\s]+$', value):
        raise ValidationError(
            _('%(value)s is not a valid remote_id'),
            params={'value': value},
        )


class ActivitypubFieldMixin:
    ''' make a database field serializable '''
    def __init__(self, *args, \
            activitypub_field=None, activitypub_wrapper=None, **kwargs):
        if activitypub_wrapper:
            self.activitypub_wrapper = activitypub_field
            self.activitypub_field = activitypub_wrapper
        else:
            self.activitypub_field = activitypub_field
        super().__init__(*args, **kwargs)

    def to_activity(self, value):
        ''' formatter to convert a model value into activitypub '''
        if hasattr(self, 'activitypub_wrapper'):
            value = {self.activitypub_wrapper: value}
        return value

    def from_activity(self, activity_data):
        ''' formatter to convert activitypub into a model value '''
        value = activity_data.get(self.activitypub_field)
        if self.activitypub_wrapper:
            value = value.get(self.activitypub_wrapper)
        return value


class RemoteIdField(ActivitypubFieldMixin, models.CharField):
    ''' a url that serves as a unique identifier '''
    def __init__(self, *args, max_length=255, validators=None, **kwargs):
        validators = validators or [validate_remote_id]
        super().__init__(
            *args, max_length=max_length, validators=validators,
            **kwargs
        )


class UsernameField(ActivitypubFieldMixin, models.CharField):
    ''' activitypub-aware username field '''
    def __init__(self, activitypub_field='preferredUsername'):
        self.activitypub_field = activitypub_field
        super(ActivitypubFieldMixin, self).__init__(
            _('username'),
            max_length=150,
            unique=True,
            validators=[AbstractUser.username_validator],
            error_messages={
                'unique': _('A user with that username already exists.'),
            },
        )

    def deconstruct(self):
        name, path, args, kwargs = super().deconstruct()
        del kwargs['verbose_name']
        del kwargs['max_length']
        del kwargs['unique']
        del kwargs['validators']
        del kwargs['error_messages']
        return name, path, args, kwargs

    def to_activity(self, value):
        return value.split('@')[0]


class ForeignKey(ActivitypubFieldMixin, models.ForeignKey):
    ''' activitypub-aware foreign key field '''
    def to_activity(self, value):
        return value.remote_id
    def from_activity(self, activity_data):
        pass# TODO


class OneToOneField(ActivitypubFieldMixin, models.OneToOneField):
    ''' activitypub-aware foreign key field '''
    def to_activity(self, value):
        return value.to_activity()

    def from_activity(self, activity_data):
        pass# TODO


class ManyToManyField(ActivitypubFieldMixin, models.ManyToManyField):
    ''' activitypub-aware many to many field '''
    def __init__(self, *args, link_only=False, **kwargs):
        self.link_only = link_only
        super().__init__(*args, **kwargs)

    def to_activity(self, value):
        if self.link_only:
            return '%s/followers' % value.instance.remote_id
        return [i.remote_id for i in value]

    def from_activity(self, activity_data):
        if self.link_only:
            return
        values = super().from_activity(self, activity_data)
        return values# TODO


class ImageField(ActivitypubFieldMixin, models.ImageField):
    ''' activitypub-aware image field '''
    def to_activity(self, value):
        if value and hasattr(value, 'url'):
            url = value.url
        else:
            return None
        url = 'https://%s%s' % (DOMAIN, url)
        return activitypub.Image(url=url)

    def from_activity(self, activity_data):
        image_slug = super().from_activity(activity_data)
        # when it's an inline image (User avatar/icon, Book cover), it's a json
        # blob, but when it's an attached image, it's just a url
        if isinstance(image_slug, dict):
            url = image_slug.get('url')
        elif isinstance(image_slug, str):
            url = image_slug
        else:
            return None
        if not url:
            return None

        response = get_image(url)
        if not response:
            return None

        image_name = str(uuid4()) + '.' + url.split('.')[-1]
        image_content = ContentFile(response.content)
        return [image_name, image_content]


class CharField(ActivitypubFieldMixin, models.CharField):
    ''' activitypub-aware char field '''

class TextField(ActivitypubFieldMixin, models.TextField):
    ''' activitypub-aware text field '''

class BooleanField(ActivitypubFieldMixin, models.BooleanField):
    ''' activitypub-aware boolean field '''