bookwyrm/bookwyrm/connectors/abstract_connector.py

""" functionality outline for a book data connector """
from abc import ABC, abstractmethod
import logging

from django.db import transaction
import requests
from requests.exceptions import RequestException

from bookwyrm import activitypub, models, settings
from .connector_manager import load_more_data, ConnectorException
from .format_mappings import format_mappings


logger = logging.getLogger(__name__)


class AbstractMinimalConnector(ABC):
    """just the bare bones, for other bookwyrm instances"""

    def __init__(self, identifier):
        # load connector settings
        info = models.Connector.objects.get(identifier=identifier)
        self.connector = info

        # the things in the connector model to copy over
        self_fields = [
            "base_url",
            "books_url",
            "covers_url",
            "search_url",
            "isbn_search_url",
            "name",
            "identifier",
        ]
        for field in self_fields:
            setattr(self, field, getattr(info, field))

    def search(self, query, min_confidence=None, timeout=settings.QUERY_TIMEOUT):
        """free text search"""
        params = {}
        if min_confidence:
            params["min_confidence"] = min_confidence

        data = self.get_search_data(
            f"{self.search_url}{query}",
            params=params,
            timeout=timeout,
        )
        results = []

        for doc in self.parse_search_data(data)[:10]:
            results.append(self.format_search_result(doc))
        return results

    def isbn_search(self, query, timeout=settings.QUERY_TIMEOUT):
        """isbn search"""
        params = {}
        data = self.get_search_data(
            f"{self.isbn_search_url}{query}",
            params=params,
            timeout=timeout,
        )
        results = []

        # this shouldn't be returning mutliple results, but just in case
        for doc in self.parse_isbn_search_data(data)[:10]:
            results.append(self.format_isbn_search_result(doc))
        return results

    def get_search_data(self, remote_id, **kwargs):  # pylint: disable=no-self-use
        """this allows connectors to override the default behavior"""
        return get_data(remote_id, **kwargs)

    @abstractmethod
    def get_or_create_book(self, remote_id):
        """pull up a book record by whatever means possible"""

    @abstractmethod
    def parse_search_data(self, data):
        """turn the result json from a search into a list"""

    @abstractmethod
    def format_search_result(self, search_result):
        """create a SearchResult obj from json"""

    @abstractmethod
    def parse_isbn_search_data(self, data):
        """turn the result json from a search into a list"""

    @abstractmethod
    def format_isbn_search_result(self, search_result):
        """create a SearchResult obj from json"""


class AbstractConnector(AbstractMinimalConnector):
    """generic book data connector"""

    def __init__(self, identifier):
        super().__init__(identifier)
        # fields we want to look for in book data to copy over
        # title we handle separately.
        self.book_mappings = []

    def get_or_create_book(self, remote_id):
        """translate arbitrary json into an Activitypub dataclass"""
        # first, check if we have the origin_id saved
        existing = models.Edition.find_existing_by_remote_id(
            remote_id
        ) or models.Work.find_existing_by_remote_id(remote_id)
        if existing:
            if hasattr(existing, "default_edition"):
                return existing.default_edition
            return existing

        # load the json data from the remote data source
        data = self.get_book_data(remote_id)
        if self.is_work_data(data):
            try:
                edition_data = self.get_edition_from_work_data(data)
            except (KeyError, ConnectorException):
                # hack: re-use the work data as the edition data
                # this is why remote ids aren't necessarily unique
                edition_data = data
            work_data = data
        else:
            edition_data = data
            try:
                work_data = self.get_work_from_edition_data(data)
            except (KeyError, ConnectorException) as err:
                logger.exception(err)
                work_data = data

        if not work_data or not edition_data:
            raise ConnectorException(f"Unable to load book data: {remote_id}")

        with transaction.atomic():
            # create activitypub object
            work_activity = activitypub.Work(
                **dict_from_mappings(work_data, self.book_mappings)
            )
            # this will dedupe automatically
            work = work_activity.to_model(model=models.Work, overwrite=False)
            for author in self.get_authors_from_data(work_data):
                work.authors.add(author)

            edition = self.create_edition_from_data(work, edition_data)
        load_more_data.delay(self.connector.id, work.id)
        return edition

    def get_book_data(self, remote_id):  # pylint: disable=no-self-use
        """this allows connectors to override the default behavior"""
        return get_data(remote_id)

    def create_edition_from_data(self, work, edition_data, instance=None):
        """if we already have the work, we're ready"""
        mapped_data = dict_from_mappings(edition_data, self.book_mappings)
        mapped_data["work"] = work.remote_id
        edition_activity = activitypub.Edition(**mapped_data)
        edition = edition_activity.to_model(
            model=models.Edition, overwrite=False, instance=instance
        )

        # if we're updating an existing instance, we don't need to load authors
        if instance:
            return edition

        if not edition.connector:
            edition.connector = self.connector
            edition.save(broadcast=False, update_fields=["connector"])

        for author in self.get_authors_from_data(edition_data):
            edition.authors.add(author)
        # use the authors from the work if none are found for the edition
        if not edition.authors.exists() and work.authors.exists():
            edition.authors.set(work.authors.all())

        return edition

    def get_or_create_author(self, remote_id, instance=None):
        """load that author"""
        if not instance:
            existing = models.Author.find_existing_by_remote_id(remote_id)
            if existing:
                return existing

        data = self.get_book_data(remote_id)

        mapped_data = dict_from_mappings(data, self.author_mappings)
        try:
            activity = activitypub.Author(**mapped_data)
        except activitypub.ActivitySerializerError:
            return None

        # this will dedupe
        return activity.to_model(
            model=models.Author, overwrite=False, instance=instance
        )

    def get_remote_id_from_model(self, obj):
        """given the data stored, how can we look this up"""
        return getattr(obj, getattr(self, "generated_remote_link_field"))

    def update_author_from_remote(self, obj):
        """load the remote data from this connector and add it to an existing author"""
        remote_id = self.get_remote_id_from_model(obj)
        return self.get_or_create_author(remote_id, instance=obj)

    def update_book_from_remote(self, obj):
        """load the remote data from this connector and add it to an existing book"""
        remote_id = self.get_remote_id_from_model(obj)
        data = self.get_book_data(remote_id)
        return self.create_edition_from_data(obj.parent_work, data, instance=obj)

    @abstractmethod
    def is_work_data(self, data):
        """differentiate works and editions"""

    @abstractmethod
    def get_edition_from_work_data(self, data):
        """every work needs at least one edition"""

    @abstractmethod
    def get_work_from_edition_data(self, data):
        """every edition needs a work"""

    @abstractmethod
    def get_authors_from_data(self, data):
        """load author data"""

    @abstractmethod
    def expand_book_data(self, book):
        """get more info on a book"""


def dict_from_mappings(data, mappings):
    """create a dict in Activitypub format, using mappings supplies by
    the subclass"""
    result = {}
    for mapping in mappings:
        # sometimes there are multiple mappings for one field, don't
        # overwrite earlier writes in that case
        if mapping.local_field in result and result[mapping.local_field]:
            continue
        result[mapping.local_field] = mapping.get_value(data)
    return result


def get_data(url, params=None, timeout=10):
    """wrapper for request.get"""
    # check if the url is blocked
    if models.FederatedServer.is_blocked(url):
        raise ConnectorException(f"Attempting to load data from blocked url: {url}")

    try:
        resp = requests.get(
            url,
            params=params,
            headers={  # pylint: disable=line-too-long
                "Accept": (
                    'application/json, application/activity+json, application/ld+json; profile="https://www.w3.org/ns/activitystreams"; charset=utf-8'
                ),
                "User-Agent": settings.USER_AGENT,
            },
            timeout=timeout,
        )
    except RequestException as err:
        logger.exception(err)
        raise ConnectorException(err)

    if not resp.ok:
        raise ConnectorException()
    try:
        data = resp.json()
    except ValueError as err:
        logger.exception(err)
        raise ConnectorException(err)

    return data


def get_image(url, timeout=10):
    """wrapper for requesting an image"""
    try:
        resp = requests.get(
            url,
            headers={
                "User-Agent": settings.USER_AGENT,
            },
            timeout=timeout,
        )
    except RequestException as err:
        logger.exception(err)
        return None
    if not resp.ok:
        return None
    return resp


class Mapping:
    """associate a local database field with a field in an external dataset"""

    def __init__(self, local_field, remote_field=None, formatter=None):
        noop = lambda x: x

        self.local_field = local_field
        self.remote_field = remote_field or local_field
        self.formatter = formatter or noop

    def get_value(self, data):
        """pull a field from incoming json and return the formatted version"""
        value = data.get(self.remote_field)
        if not value:
            return None
        try:
            return self.formatter(value)
        except:  # pylint: disable=bare-except
            return None


def infer_physical_format(format_text):
    """try to figure out what the standardized format is from the free value"""
    format_text = format_text.lower()
    if format_text in format_mappings:
        # try a direct match
        return format_mappings[format_text]
    # failing that, try substring
    matches = [v for k, v in format_mappings.items() if k in format_text]
    if not matches:
        return None
    return matches[0]


def unique_physical_format(format_text):
    """only store the format if it isn't diretly in the format mappings"""
    format_text = format_text.lower()
    if format_text in format_mappings:
        # try a direct match, so saving this would be redundant
        return None
    return format_text