# Source code for searx.engines.wikidata

    # SPDX-License-Identifier: AGPL-3.0-or-later
    """This module implements the Wikidata engine.  Some implementations are shared
    from :ref:`wikipedia engine`.

    """
    # pylint: disable=missing-class-docstring

    from typing import TYPE_CHECKING
    from hashlib import md5
    from urllib.parse import urlencode, unquote
    from json import loads

    from dateutil.parser import isoparse
    from babel.dates import format_datetime, format_date, format_time, get_datetime_format

    from searx.data import WIKIDATA_UNITS
    from searx.network import post, get
    from searx.utils import searx_useragent, get_string_replaces_function
    from searx.external_urls import get_external_url, get_earth_coordinates_url, area_to_osm_zoom
    from searx.engines.wikipedia import (
        fetch_wikimedia_traits,
        get_wiki_params,
    )
    from searx.enginelib.traits import EngineTraits

    if TYPE_CHECKING:
        import logging

        logger: logging.Logger

    traits: EngineTraits

    # about
    about = {
        "website": 'https://wikidata.org/',
        "wikidata_id": 'Q2013',
        "official_api_documentation": 'https://query.wikidata.org/',
        "use_official_api": True,
        "require_api_key": False,
        "results": 'JSON',
    }

    display_type = ["infobox"]
    """A list of display types composed from ``infobox`` and ``list``.  The latter
    one will add a hit to the result list.  The first one will show a hit in the
    info box.  Both values can be set, or one of the two can be set."""

    # SPARQL
    SPARQL_ENDPOINT_URL = 'https://query.wikidata.org/sparql'
    SPARQL_EXPLAIN_URL = 'https://query.wikidata.org/bigdata/namespace/wdq/sparql?explain'
    WIKIDATA_PROPERTIES = {
        'P434': 'MusicBrainz',
        'P435': 'MusicBrainz',
        'P436': 'MusicBrainz',
        'P966': 'MusicBrainz',
        'P345': 'IMDb',
        'P2397': 'YouTube',
        'P1651': 'YouTube',
        'P2002': 'Twitter',
        'P2013': 'Facebook',
        'P2003': 'Instagram',
    }

    # SERVICE wikibase:mwapi : https://www.mediawiki.org/wiki/Wikidata_Query_Service/User_Manual/MWAPI
    # SERVICE wikibase:label: https://en.wikibooks.org/wiki/SPARQL/SERVICE_-_Label#Manual_Label_SERVICE
    # https://en.wikibooks.org/wiki/SPARQL/WIKIDATA_Precision,_Units_and_Coordinates
    # https://www.mediawiki.org/wiki/Wikibase/Indexing/RDF_Dump_Format#Data_model
    # optimization:
    # * https://www.wikidata.org/wiki/Wikidata:SPARQL_query_service/query_optimization
    # * https://github.com/blazegraph/database/wiki/QueryHints
    QUERY_TEMPLATE = """
    SELECT ?item ?itemLabel ?itemDescription ?lat ?long %SELECT%
    WHERE
    {
      SERVICE wikibase:mwapi {
            bd:serviceParam wikibase:endpoint "www.wikidata.org";
            wikibase:api "EntitySearch";
            wikibase:limit 1;
            mwapi:search "%QUERY%";
            mwapi:language "%LANGUAGE%".
            ?item wikibase:apiOutputItem mwapi:item.
      }
      hint:Prior hint:runFirst "true".

      %WHERE%

      SERVICE wikibase:label {
          bd:serviceParam wikibase:language "%LANGUAGE%,en".
          ?item rdfs:label ?itemLabel .
          ?item schema:description ?itemDescription .
          %WIKIBASE_LABELS%
      }

    }
    GROUP BY ?item ?itemLabel ?itemDescription ?lat ?long %GROUP_BY%
    """

    # Get the calendar names and the property names
    QUERY_PROPERTY_NAMES = """
    SELECT ?item ?name
    WHERE {
        {
          SELECT ?item
          WHERE { ?item wdt:P279* wd:Q12132 }
        } UNION {
          VALUES ?item { %ATTRIBUTES% }
        }
        OPTIONAL { ?item rdfs:label ?name. }
    }
    """

    # see the property "dummy value" of https://www.wikidata.org/wiki/Q2013 (Wikidata)
    # hard coded here to avoid to an additional SPARQL request when the server starts
    DUMMY_ENTITY_URLS = set(
        "http://www.wikidata.org/entity/" + wid for wid in ("Q4115189", "Q13406268", "Q15397819", "Q17339402")
    )

    # https://www.w3.org/TR/sparql11-query/#rSTRING_LITERAL1
    # https://lists.w3.org/Archives/Public/public-rdf-dawg/2011OctDec/0175.html
    sparql_string_escape = get_string_replaces_function(
        # fmt: off
        {
            '\t': '\\\t',
            '\n': '\\\n',
            '\r': '\\\r',
            '\b': '\\\b',
            '\f': '\\\f',
            '\"': '\\\"',
            '\'': '\\\'',
            '\\': '\\\\'
        }
        # fmt: on
    )

    replace_http_by_https = get_string_replaces_function({'http:': 'https:'})

    def get_headers():
        # user agent: https://www.mediawiki.org/wiki/Wikidata_Query_Service/User_Manual#Query_limits
        return {'Accept': 'application/sparql-results+json', 'User-Agent': searx_useragent()}

    def get_label_for_entity(entity_id, language):
        name = WIKIDATA_PROPERTIES.get(entity_id)
        if name is None:
            name = WIKIDATA_PROPERTIES.get((entity_id, language))
        if name is None:
            name = WIKIDATA_PROPERTIES.get((entity_id, language.split('-')[0]))
        if name is None:
            name = WIKIDATA_PROPERTIES.get((entity_id, 'en'))
        if name is None:
            name = entity_id
        return name

    def send_wikidata_query(query, method='GET'):
        if method == 'GET':
            # query will be cached by wikidata
            http_response = get(SPARQL_ENDPOINT_URL + '?' + urlencode({'query': query}), headers=get_headers())
        else:
            # query won't be cached by wikidata
            http_response = post(SPARQL_ENDPOINT_URL, data={'query': query}, headers=get_headers())
        if http_response.status_code != 200:
            logger.debug('SPARQL endpoint error %s', http_response.content.decode())
        logger.debug('request time %s', str(http_response.elapsed))
        http_response.raise_for_status()
        return loads(http_response.content.decode())

    def request(query, params):

        eng_tag, _wiki_netloc = get_wiki_params(params['searxng_locale'], traits)
        query, attributes = get_query(query, eng_tag)
        logger.debug("request --> language %s // len(attributes): %s", eng_tag, len(attributes))

        params['method'] = 'POST'
        params['url'] = SPARQL_ENDPOINT_URL
        params['data'] = {'query': query}
        params['headers'] = get_headers()
        params['language'] = eng_tag
        params['attributes'] = attributes

        return params

    def response(resp):

        results = []
        jsonresponse = loads(resp.content.decode())

        language = resp.search_params['language']
        attributes = resp.search_params['attributes']
        logger.debug("request --> language %s // len(attributes): %s", language, len(attributes))

        seen_entities = set()
        for result in jsonresponse.get('results', {}).get('bindings', []):
            attribute_result = {key: value['value'] for key, value in result.items()}
            entity_url = attribute_result['item']
            if entity_url not in seen_entities and entity_url not in DUMMY_ENTITY_URLS:
                seen_entities.add(entity_url)
                results += get_results(attribute_result, attributes, language)
            else:
                logger.debug('The SPARQL request returns duplicate entities: %s', str(attribute_result))

        return results

    _IMG_SRC_DEFAULT_URL_PREFIX = "https://commons.wikimedia.org/wiki/Special:FilePath/"
    _IMG_SRC_NEW_URL_PREFIX = "https://upload.wikimedia.org/wikipedia/commons/thumb/"

    def get_thumbnail(img_src):
        """Get Thumbnail image from wikimedia commons

        Images from commons.wikimedia.org are (HTTP) redirected to
        upload.wikimedia.org.  The redirected URL can be calculated by this
        function.

        - https://stackoverflow.com/a/33691240

        """
        logger.debug('get_thumbnail(): %s', img_src)
        if not img_src is None and _IMG_SRC_DEFAULT_URL_PREFIX in img_src.split()[0]:
            img_src_name = unquote(img_src.replace(_IMG_SRC_DEFAULT_URL_PREFIX, "").split("?", 1)[0].replace("%20", "_"))
            img_src_name_first = img_src_name
            img_src_name_second = img_src_name

            if ".svg" in img_src_name.split()[0]:
                img_src_name_second = img_src_name + ".png"

            img_src_size = img_src.replace(_IMG_SRC_DEFAULT_URL_PREFIX, "").split("?", 1)[1]
            img_src_size = img_src_size[img_src_size.index("=") + 1 : img_src_size.index("&")]
            img_src_name_md5 = md5(img_src_name.encode("utf-8")).hexdigest()
            img_src = (
                _IMG_SRC_NEW_URL_PREFIX
                + img_src_name_md5[0]
                + "/"
                + img_src_name_md5[0:2]
                + "/"
                + img_src_name_first
                + "/"
                + img_src_size
                + "px-"
                + img_src_name_second
            )
            logger.debug('get_thumbnail() redirected: %s', img_src)

        return img_src

    def get_results(attribute_result, attributes, language):
        # pylint: disable=too-many-branches
        results = []
        infobox_title = attribute_result.get('itemLabel')
        infobox_id = attribute_result['item']
        infobox_id_lang = None
        infobox_urls = []
        infobox_attributes = []
        infobox_content = attribute_result.get('itemDescription', [])
        img_src = None
        img_src_priority = 0

        for attribute in attributes:
            value = attribute.get_str(attribute_result, language)
            if value is not None and value != '':
                attribute_type = type(attribute)

                if attribute_type in (WDURLAttribute, WDArticle):
                    # get_select() method : there is group_concat(distinct ...;separator=", ")
                    # split the value here
                    for url in value.split(', '):
                        infobox_urls.append({'title': attribute.get_label(language), 'url': url, **attribute.kwargs})
                        # "normal" results (not infobox) include official website and Wikipedia links.
                        if "list" in display_type and (attribute.kwargs.get('official') or attribute_type == WDArticle):
                            results.append({'title': infobox_title, 'url': url, "content": infobox_content})

                        # update the infobox_id with the wikipedia URL
                        # first the local wikipedia URL, and as fallback the english wikipedia URL
                        if attribute_type == WDArticle and (
                            (attribute.language == 'en' and infobox_id_lang is None) or attribute.language != 'en'
                        ):
                            infobox_id_lang = attribute.language
                            infobox_id = url
                elif attribute_type == WDImageAttribute:
                    # this attribute is an image.
                    # replace the current image only the priority is lower
                    # (the infobox contain only one image).
                    if attribute.priority > img_src_priority:
                        img_src = get_thumbnail(value)
                        img_src_priority = attribute.priority
                elif attribute_type == WDGeoAttribute:
                    # geocoordinate link
                    # use the area to get the OSM zoom
                    # Note: ignore the unit (must be km² otherwise the calculation is wrong)
                    # Should use normalized value p:P2046/psn:P2046/wikibase:quantityAmount
                    area = attribute_result.get('P2046')
                    osm_zoom = area_to_osm_zoom(area) if area else 19
                    url = attribute.get_geo_url(attribute_result, osm_zoom=osm_zoom)
                    if url:
                        infobox_urls.append({'title': attribute.get_label(language), 'url': url, 'entity': attribute.name})
                else:
                    infobox_attributes.append(
                        {'label': attribute.get_label(language), 'value': value, 'entity': attribute.name}
                    )

        if infobox_id:
            infobox_id = replace_http_by_https(infobox_id)

        # add the wikidata URL at the end
        infobox_urls.append({'title': 'Wikidata', 'url': attribute_result['item']})

        if (
            "list" in display_type
            and img_src is None
            and len(infobox_attributes) == 0
            and len(infobox_urls) == 1
            and len(infobox_content) == 0
        ):
            results.append({'url': infobox_urls[0]['url'], 'title': infobox_title, 'content': infobox_content})
        elif "infobox" in display_type:
            results.append(
                {
                    'infobox': infobox_title,
                    'id': infobox_id,
                    'content': infobox_content,
                    'img_src': img_src,
                    'urls': infobox_urls,
                    'attributes': infobox_attributes,
                }
            )
        return results

    def get_query(query, language):
        attributes = get_attributes(language)
        select = [a.get_select() for a in attributes]
        where = list(filter(lambda s: len(s) > 0, [a.get_where() for a in attributes]))
        wikibase_label = list(filter(lambda s: len(s) > 0, [a.get_wikibase_label() for a in attributes]))
        group_by = list(filter(lambda s: len(s) > 0, [a.get_group_by() for a in attributes]))
        query = (
            QUERY_TEMPLATE.replace('%QUERY%', sparql_string_escape(query))
            .replace('%SELECT%', ' '.join(select))
            .replace('%WHERE%', '\n  '.join(where))
            .replace('%WIKIBASE_LABELS%', '\n      '.join(wikibase_label))
            .replace('%GROUP_BY%', ' '.join(group_by))
            .replace('%LANGUAGE%', language)
        )
        return query, attributes

    def get_attributes(language):
        # pylint: disable=too-many-statements
        attributes = []

        def add_value(name):
            attributes.append(WDAttribute(name))

        def add_amount(name):
            attributes.append(WDAmountAttribute(name))

        def add_label(name):
            attributes.append(WDLabelAttribute(name))

        def add_url(name, url_id=None, **kwargs):
            attributes.append(WDURLAttribute(name, url_id, kwargs))

        def add_image(name, url_id=None, priority=1):
            attributes.append(WDImageAttribute(name, url_id, priority))

        def add_date(name):
            attributes.append(WDDateAttribute(name))

        # Dates
        for p in [
            'P571',  # inception date
            'P576',  # dissolution date
            'P580',  # start date
            'P582',  # end date
            'P569',  # date of birth
            'P570',  # date of death
            'P619',  # date of spacecraft launch
            'P620',
        ]:  # date of spacecraft landing
            add_date(p)

        for p in [
            'P27',  # country of citizenship
            'P495',  # country of origin
            'P17',  # country
            'P159',
        ]:  # headquarters location
            add_label(p)

        # Places
        for p in [
            'P36',  # capital
            'P35',  # head of state
            'P6',  # head of government
            'P122',  # basic form of government
            'P37',
        ]:  # official language
            add_label(p)

        add_value('P1082')  # population
        add_amount('P2046')  # area
        add_amount('P281')  # postal code
        add_label('P38')  # currency
        add_amount('P2048')  # height (building)

        # Media
        for p in [
            'P400',  # platform (videogames, computing)
            'P50',  # author
            'P170',  # creator
            'P57',  # director
            'P175',  # performer
            'P178',  # developer
            'P162',  # producer
            'P176',  # manufacturer
            'P58',  # screenwriter
            'P272',  # production company
            'P264',  # record label
            'P123',  # publisher
            'P449',  # original network
            'P750',  # distributed by
            'P86',
        ]:  # composer
            add_label(p)

        add_date('P577')  # publication date
        add_label('P136')  # genre (music, film, artistic...)
        add_label('P364')  # original language
        add_value('P212')  # ISBN-13
        add_value('P957')  # ISBN-10
        add_label('P275')  # copyright license
        add_label('P277')  # programming language
        add_value('P348')  # version
        add_label('P840')  # narrative location

        # Languages
        add_value('P1098')  # number of speakers
        add_label('P282')  # writing system
        add_label('P1018')  # language regulatory body
        add_value('P218')  # language code (ISO 639-1)

        # Other
        add_label('P169')  # ceo
        add_label('P112')  # founded by
        add_label('P1454')  # legal form (company, organization)
        add_label('P137')  # operator (service, facility, ...)
        add_label('P1029')  # crew members (tripulation)
        add_label('P225')  # taxon name
        add_value('P274')  # chemical formula
        add_label('P1346')  # winner (sports, contests, ...)
        add_value('P1120')  # number of deaths
        add_value('P498')  # currency code (ISO 4217)

        # URL
        add_url('P856', official=True)  # official website
        attributes.append(WDArticle(language))  # wikipedia (user language)
        if not language.startswith('en'):
            attributes.append(WDArticle('en'))  # wikipedia (english)

        add_url('P1324')  # source code repository
        add_url('P1581')  # blog
        add_url('P434', url_id='musicbrainz_artist')
        add_url('P435', url_id='musicbrainz_work')
        add_url('P436', url_id='musicbrainz_release_group')
        add_url('P966', url_id='musicbrainz_label')
        add_url('P345', url_id='imdb_id')
        add_url('P2397', url_id='youtube_channel')
        add_url('P1651', url_id='youtube_video')
        add_url('P2002', url_id='twitter_profile')
        add_url('P2013', url_id='facebook_profile')
        add_url('P2003', url_id='instagram_profile')

        # Map
        attributes.append(WDGeoAttribute('P625'))

        # Image
        add_image('P15', priority=1, url_id='wikimedia_image')  # route map
        add_image('P242', priority=2, url_id='wikimedia_image')  # locator map
        add_image('P154', priority=3, url_id='wikimedia_image')  # logo
        add_image('P18', priority=4, url_id='wikimedia_image')  # image
        add_image('P41', priority=5, url_id='wikimedia_image')  # flag
        add_image('P2716', priority=6, url_id='wikimedia_image')  # collage
        add_image('P2910', priority=7, url_id='wikimedia_image')  # icon

        return attributes

    class WDAttribute:
        __slots__ = ('name',)

        def __init__(self, name):
            self.name = name

        def get_select(self):
            return '(group_concat(distinct ?{name};separator=", ") as ?{name}s)'.replace('{name}', self.name)

        def get_label(self, language):
            return get_label_for_entity(self.name, language)

        def get_where(self):
            return "OPTIONAL { ?item wdt:{name} ?{name} . }".replace('{name}', self.name)

        def get_wikibase_label(self):
            return ""

        def get_group_by(self):
            return ""

        def get_str(self, result, language):  # pylint: disable=unused-argument
            return result.get(self.name + 's')

        def __repr__(self):
            return '<' + str(type(self).__name__) + ':' + self.name + '>'

    class WDAmountAttribute(WDAttribute):
        def get_select(self):
            return '?{name} ?{name}Unit'.replace('{name}', self.name)

        def get_where(self):
            return """  OPTIONAL { ?item p:{name} ?{name}Node .
        ?{name}Node rdf:type wikibase:BestRank ; ps:{name} ?{name} .
        OPTIONAL { ?{name}Node psv:{name}/wikibase:quantityUnit ?{name}Unit. } }""".replace(
                '{name}', self.name
            )

        def get_group_by(self):
            return self.get_select()

        def get_str(self, result, language):
            value = result.get(self.name)
            unit = result.get(self.name + "Unit")
            if unit is not None:
                unit = unit.replace('http://www.wikidata.org/entity/', '')
                return value + " " + get_label_for_entity(unit, language)
            return value

    class WDArticle(WDAttribute):

        __slots__ = 'language', 'kwargs'

        def __init__(self, language, kwargs=None):
            super().__init__('wikipedia')
            self.language = language
            self.kwargs = kwargs or {}

        def get_label(self, language):
            # language parameter is ignored
            return "Wikipedia ({language})".replace('{language}', self.language)

        def get_select(self):
            return "?article{language} ?articleName{language}".replace('{language}', self.language)

        def get_where(self):
            return """OPTIONAL { ?article{language} schema:about ?item ;
                 schema:inLanguage "{language}" ;
                 schema:isPartOf <https://{language}.wikipedia.org/> ;
                 schema:name ?articleName{language} . }""".replace(
                '{language}', self.language
            )

        def get_group_by(self):
            return self.get_select()

        def get_str(self, result, language):
            key = 'article{language}'.replace('{language}', self.language)
            return result.get(key)

    class WDLabelAttribute(WDAttribute):
        def get_select(self):
            return '(group_concat(distinct ?{name}Label;separator=", ") as ?{name}Labels)'.replace('{name}', self.name)

        def get_where(self):
            return "OPTIONAL { ?item wdt:{name} ?{name} . }".replace('{name}', self.name)

        def get_wikibase_label(self):
            return "?{name} rdfs:label ?{name}Label .".replace('{name}', self.name)

        def get_str(self, result, language):
            return result.get(self.name + 'Labels')

    class WDURLAttribute(WDAttribute):

        HTTP_WIKIMEDIA_IMAGE = 'http://commons.wikimedia.org/wiki/Special:FilePath/'

        __slots__ = 'url_id', 'kwargs'

        def __init__(self, name, url_id=None, kwargs=None):
            super().__init__(name)
            self.url_id = url_id
            self.kwargs = kwargs

        def get_str(self, result, language):
            value = result.get(self.name + 's')
            if self.url_id and value is not None and value != '':
                value = value.split(',')[0]
                url_id = self.url_id
                if value.startswith(WDURLAttribute.HTTP_WIKIMEDIA_IMAGE):
                    value = value[len(WDURLAttribute.HTTP_WIKIMEDIA_IMAGE) :]
                    url_id = 'wikimedia_image'
                return get_external_url(url_id, value)
            return value

    class WDGeoAttribute(WDAttribute):
        def get_label(self, language):
            return "OpenStreetMap"

        def get_select(self):
            return "?{name}Lat ?{name}Long".replace('{name}', self.name)

        def get_where(self):
            return """OPTIONAL { ?item p:{name}/psv:{name} [
        wikibase:geoLatitude ?{name}Lat ;
        wikibase:geoLongitude ?{name}Long ] }""".replace(
                '{name}', self.name
            )

        def get_group_by(self):
            return self.get_select()

        def get_str(self, result, language):
            latitude = result.get(self.name + 'Lat')
            longitude = result.get(self.name + 'Long')
            if latitude and longitude:
                return latitude + ' ' + longitude
            return None

        def get_geo_url(self, result, osm_zoom=19):
            latitude = result.get(self.name + 'Lat')
            longitude = result.get(self.name + 'Long')
            if latitude and longitude:
                return get_earth_coordinates_url(latitude, longitude, osm_zoom)
            return None

    class WDImageAttribute(WDURLAttribute):

        __slots__ = ('priority',)

        def __init__(self, name, url_id=None, priority=100):
            super().__init__(name, url_id)
            self.priority = priority

    class WDDateAttribute(WDAttribute):
        def get_select(self):
            return '?{name} ?{name}timePrecision ?{name}timeZone ?{name}timeCalendar'.replace('{name}', self.name)

        def get_where(self):
            # To remove duplicate, add
            # FILTER NOT EXISTS { ?item p:{name}/psv:{name}/wikibase:timeValue ?{name}bis FILTER (?{name}bis < ?{name}) }
            # this filter is too slow, so the response function ignore duplicate results
            # (see the seen_entities variable)
            return """OPTIONAL { ?item p:{name}/psv:{name} [
        wikibase:timeValue ?{name} ;
        wikibase:timePrecision ?{name}timePrecision ;
        wikibase:timeTimezone ?{name}timeZone ;
        wikibase:timeCalendarModel ?{name}timeCalendar ] . }
        hint:Prior hint:rangeSafe true;""".replace(
                '{name}', self.name
            )

        def get_group_by(self):
            return self.get_select()

        def format_8(self, value, locale):  # pylint: disable=unused-argument
            # precision: less than a year
            return value

        def format_9(self, value, locale):
            year = int(value)
            # precision: year
            if year < 1584:
                if year < 0:
                    return str(year - 1)
                return str(year)
            timestamp = isoparse(value)
            return format_date(timestamp, format='yyyy', locale=locale)

        def format_10(self, value, locale):
            # precision: month
            timestamp = isoparse(value)
            return format_date(timestamp, format='MMMM y', locale=locale)

        def format_11(self, value, locale):
            # precision: day
            timestamp = isoparse(value)
            return format_date(timestamp, format='full', locale=locale)

        def format_13(self, value, locale):
            timestamp = isoparse(value)
            # precision: minute
            return (
                get_datetime_format(format, locale=locale)
                .replace("'", "")
                .replace('{0}', format_time(timestamp, 'full', tzinfo=None, locale=locale))
                .replace('{1}', format_date(timestamp, 'short', locale=locale))
            )

        def format_14(self, value, locale):
            # precision: second.
            return format_datetime(isoparse(value), format='full', locale=locale)

        DATE_FORMAT = {
            '0': ('format_8', 1000000000),
            '1': ('format_8', 100000000),
            '2': ('format_8', 10000000),
            '3': ('format_8', 1000000),
            '4': ('format_8', 100000),
            '5': ('format_8', 10000),
            '6': ('format_8', 1000),
            '7': ('format_8', 100),
            '8': ('format_8', 10),
            '9': ('format_9', 1),  # year
            '10': ('format_10', 1),  # month
            '11': ('format_11', 0),  # day
            '12': ('format_13', 0),  # hour (not supported by babel, display minute)
            '13': ('format_13', 0),  # minute
            '14': ('format_14', 0),  # second
        }

        def get_str(self, result, language):
            value = result.get(self.name)
            if value == '' or value is None:
                return None
            precision = result.get(self.name + 'timePrecision')
            date_format = WDDateAttribute.DATE_FORMAT.get(precision)
            if date_format is not None:
                format_method = getattr(self, date_format[0])
                precision = date_format[1]
                try:
                    if precision >= 1:
                        t = value.split('-')
                        if value.startswith('-'):
                            value = '-' + t[1]
                        else:
                            value = t[0]
                    return format_method(value, language)
                except Exception:  # pylint: disable=broad-except
                    return value
            return value

    def debug_explain_wikidata_query(query, method='GET'):
        if method == 'GET':
            http_response = get(SPARQL_EXPLAIN_URL + '&' + urlencode({'query': query}), headers=get_headers())
        else:
            http_response = post(SPARQL_EXPLAIN_URL, data={'query': query}, headers=get_headers())
        http_response.raise_for_status()
        return http_response.content

    def init(engine_settings=None):  # pylint: disable=unused-argument
        # WIKIDATA_PROPERTIES : add unit symbols
        for k, v in WIKIDATA_UNITS.items():
            WIKIDATA_PROPERTIES[k] = v['symbol']

        # WIKIDATA_PROPERTIES : add property labels
        wikidata_property_names = []
        for attribute in get_attributes('en'):
            if type(attribute) in (WDAttribute, WDAmountAttribute, WDURLAttribute, WDDateAttribute, WDLabelAttribute):
                if attribute.name not in WIKIDATA_PROPERTIES:
                    wikidata_property_names.append("wd:" + attribute.name)
        query = QUERY_PROPERTY_NAMES.replace('%ATTRIBUTES%', " ".join(wikidata_property_names))
        jsonresponse = send_wikidata_query(query)
        for result in jsonresponse.get('results', {}).get('bindings', {}):
            name = result['name']['value']
            lang = result['name']['xml:lang']
            entity_id = result['item']['value'].replace('http://www.wikidata.org/entity/', '')
            WIKIDATA_PROPERTIES[(entity_id, lang)] = name.capitalize()

    def fetch_traits(engine_traits: EngineTraits):
        """Uses languages evaluated from :py:obj:`wikipedia.fetch_wikimedia_traits
        <searx.engines.wikipedia.fetch_wikimedia_traits>` and removes

        - ``traits.custom['wiki_netloc']``: wikidata does not have net-locations for
          the languages and the list of all

        - ``traits.custom['WIKIPEDIA_LANGUAGES']``: not used in the wikipedia engine

        """

        fetch_wikimedia_traits(engine_traits)
        engine_traits.custom['wiki_netloc'] = {}
        engine_traits.custom['WIKIPEDIA_LANGUAGES'] = []