moviewyrm/bookwyrm/models/fields.py

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

from django.contrib.auth.models import AbstractUser
from django.contrib.postgres.fields import ArrayField as DjangoArrayField
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 field_to_activity(self, value):
        ''' formatter to convert a model value into activitypub '''
        if hasattr(self, 'activitypub_wrapper'):
            return {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

    def get_activitypub_field(self):
        ''' model_field_name to activitypubFieldName '''
        if self.activitypub_field:
            return self.activitypub_field
        name = self.name.split('.')[-1]
        components = name.split('_')
        return components[0] + ''.join(x.title() for x in components[1:])


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):
        ''' implementation of models.Field deconstruct '''
        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 field_to_activity(self, value):
        return value.split('@')[0]


class ForeignKey(ActivitypubFieldMixin, models.ForeignKey):
    ''' activitypub-aware foreign key field '''
    def field_to_activity(self, value):
        if not value:
            return None
        return value.remote_id


class OneToOneField(ActivitypubFieldMixin, models.OneToOneField):
    ''' activitypub-aware foreign key field '''
    def field_to_activity(self, value):
        if not value:
            return None
        return value.to_activity()


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

    def from_activity(self, activity_data):
        if self.link_only:
            return None
        values = super().from_activity(activity_data)
        return values# TODO


class TagField(ManyToManyField):
    ''' special case of many to many that uses Tags '''
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.activitypub_field = 'tag'

    def field_to_activity(self, value):
        tags = []
        for item in value.all():
            activity_type = item.__class__.__name__
            if activity_type == 'User':
                activity_type = 'Mention'
            tags.append(activitypub.Link(
                href=item.remote_id,
                name=getattr(item, item.name_field),
                type=activity_type
            ))
        return tags


def image_serializer(value):
    ''' helper for serializing images '''
    if value and hasattr(value, 'url'):
        url = value.url
    else:
        return None
    url = 'https://%s%s' % (DOMAIN, url)
    return activitypub.Image(url=url)


class ImageField(ActivitypubFieldMixin, models.ImageField):
    ''' activitypub-aware image field '''
    def field_to_activity(self, value):
        return image_serializer(value)

    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 DateTimeField(ActivitypubFieldMixin, models.DateTimeField):
    ''' activitypub-aware datetime field '''
    def field_to_activity(self, value):
        if not value:
            return None
        return value.isoformat()

class ArrayField(ActivitypubFieldMixin, DjangoArrayField):
    ''' activitypub-aware array field '''
    def field_to_activity(self, value):
        return [str(i) for i in value]

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 '''

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