Module:Sources-utils

Documentation for this module may be created at Module:Sources-utils/doc
local p = {};

local i18nDefaultLanguage = 'ru';
p.i18nDefaultLanguage = i18nDefaultLanguage;

local NORMATIVE_DOCUMENTS = {
	Q20754888 = 'Закон Российской Федерации',
	Q20754884 = 'Закон РСФСР',
	Q20873831 = 'Распоряжение Президента Российской Федерации',
	Q20873834 = 'Указ исполняющего обязанности Президента Российской Федерации',
	Q2061228 = 'Указ Президента Российской Федерации',
}

local monthg = {'января', 'февраля', 'марта', 'апреля', 'мая', 'июня', 'июля', 'августа', "сентября", "октября", "ноября", "декабря"};

local options_commas_nolinks = { separator = ', ', conjunction = ', ', format = function( src ) return src end, nolinks = true, preferids = false };

-- utility functions
function appendSnaks( allSnaks, snakPropertyId, result, property, options )
	-- do not populate twice
	if ( result[property] ) then return result end;
	if ( not allSnaks ) then return result; end;
	
	local selectedSnakes = allSnaks[ snakPropertyId ];
	if ( not selectedSnakes ) then return result; end;

	local hasPreferred = false;
	for k, snak in pairs( selectedSnakes ) do
		if ( snak and snak.mainsnak and snak.mainsnak.datavalue and snak.rank == 'preferred' ) then
			--it's a preferred claim
			appendImpl( snak.mainsnak.datavalue, snak.qualifiers, result, property, options );
			hasPreferred = true;
		end
	end
	if ( hasPreferred ) then return result; end;

	if ( snakPropertyId == 'P1680' ) then -- if there is a russian 
		for k, snak in pairs( selectedSnakes ) do
			if ( snak and snak.mainsnak and snak.mainsnak.datavalue and snak.mainsnak.datavalue.value and 
				 snak.rank ~= 'deprecated' and snak.mainsnak.datavalue.value.language  == i18nDefaultLanguage ) then
				--found russian string
				appendImpl( snak.mainsnak.datavalue, snak.qualifiers, result, property, options );
				return result;
			end
		end
	end;

	for k, snak in pairs( selectedSnakes ) do
		if ( snak and snak.mainsnak and snak.mainsnak.datavalue and snak.rank ~= 'deprecated' ) then
			--it's a claim
			appendImpl( snak.mainsnak.datavalue, snak.qualifiers, result, property, options );
		elseif ( snak and snak.datavalue ) then
			-- it's a snak
			appendImpl( snak.datavalue, nil, result, property, options );
		end
	end
end

function appendImpl( datavalue, qualifiers, result, property, options )
	if ( datavalue.type == 'string' ) then
		local statedAs = getSingleStringQualifierValue(qualifiers, 'P1932');
		local value;
		if ( statedAs ) then
			value = statedAs;
		else
			value = datavalue.value;
			if ( options.format ) then
				value = options.format( value );
			end
		end
		appendImpl_toTable( result, property );
		table.insert( result[property], value);
	elseif ( datavalue.type == 'url' ) then
		local statedAs = getSingleStringQualifierValue(qualifiers, 'P1932');
		local value = datavalue.value;
		if ( options.format ) then
			value = options.format( value );
		end
		appendImpl_toTable( result, property );
		table.insert( result[property], value);
	elseif ( datavalue.type == 'monolingualtext' ) then
		local value = datavalue.value.text;
		if ( options.format ) then
			value = options.format( value );
		end
		appendImpl_toTable( result, property );
		table.insert( result[property], value);
	elseif ( datavalue.type == 'quantity' ) then
		local value = datavalue.value.amount;
		if ( mw.ustring.sub( value , 1, 1 ) == '+' ) then
			value = mw.ustring.sub( value , 2 );
		end
		if ( options.format ) then
			value = options.format( value );
		end
		appendImpl_toTable( result, property );
		table.insert( result[property], value);
	elseif ( datavalue.type == 'wikibase-entityid' ) then
		local value = datavalue.value;
		appendImpl_toTable( result, property );
		local toInsert = {
			id = value.id,
			label = getSingleStringQualifierValue(qualifiers, 'P1932') -- stated as
		};
		table.insert( result[property], toInsert );
	elseif datavalue.type == 'time' then
		local value = datavalue.value;
		if ( options.format ) then
			value = options.format( value );
		end
		appendImpl_toTable( result, property );
		table.insert( result[property], tostring( value.time ));
    end 
end

function appendImpl_toTable(result, resultProperty)
	if ( not result[resultProperty] ) then
		result[resultProperty] = {};
	elseif ( type( result[resultProperty] ) == 'string' or ( type( result[resultProperty] ) == 'table' and type( result[resultProperty].id ) == 'string' ) ) then
		result[resultProperty] = { result[resultProperty] };
	end
end

function appendQualifiers( claims, qualifierPropertyId, result, resultProperty, options )
	-- do not populate twice
	if ( not claims ) then return result end;
	if ( result[resultProperty] ) then return result end;

	for i, claim in pairs( claims ) do
		if ( claim.qualifiers and claim.qualifiers[ qualifierPropertyId ] ) then
			for k, qualifier in pairs( claim.qualifiers[ qualifierPropertyId ] ) do
				if ( qualifier and qualifier.datavalue ) then
					appendImpl( qualifier.datavalue, nil, result, resultProperty, options );
				end
			end
		end
	end
end

function assertNotNull( argName, arg )
	if ( (not arg) or (arg == nil) ) then
		error( argName .. ' is not specified' )
	end
end

function coalesce( arg1, arg2, arg3, arg4 )
	if ( not isEmpty( arg1 ) ) then return arg1 end
	if ( not isEmpty( arg2 ) ) then return arg2 end
	if ( not isEmpty( arg3 ) ) then return arg3 end
	if ( not isEmpty( arg4 ) ) then return arg4 end
	return nil;
end

function copyArgsToSnaks( args, snaks )
	if ( not isEmpty( args.part ) ) then snaks.P958 = { toStringSnak( 'P958', tostring( args.part ) ) } end
	if ( not isEmpty( args.pages ) ) then snaks.P304 = { toStringSnak( 'P304', tostring( args.pages ) ) } end
	if ( not isEmpty( args.issue ) ) then snaks.P433 = { toStringSnak( 'P433', tostring( args.issue ) ) } end
	if ( not isEmpty( args.volume ) ) then snaks.P478 = { toStringSnak( 'P478', tostring( args.volume ) ) } end
	if ( not isEmpty( args.url ) ) then snaks.P953 = { toUrlSnak( 'P953', tostring( args.url ) ) } end
	if ( not isEmpty( args.parturl ) ) then snaks.P953 = { toUrlSnak( 'P953', tostring( args.parturl ) ) } end
end

local LANG_CACHE = 	{
	Q150	= 'fr',
	Q188	= 'de',
	Q1321	= 'es',
	Q1860	= 'en',
	Q652	= 'it',
	Q7737	= 'ru',
}

function getLangCode( langEntityId )
	if ( not langEntityId ) then
		return;
	end

	-- small optimization
	local cached = LANG_CACHE[ langEntityId ];
	if ( cached ) then return cached; end

	local claims = mw.wikibase.getBestStatements( langEntityId, 'P424' );
	if ( claims ) then
		for _, claim in pairs( claims ) do
			if ( claim
					and claim.mainsnak
					and claim.mainsnak.datavalue
					and claim.mainsnak.datavalue.value ) then
				return '' .. claim.mainsnak.datavalue.value;
			end
		end
	end

	return;
end

function findClaimsByValue( entity, propertyId, value )
	local result = {};
	if ( entity and entity.claims and entity.claims[propertyId] ) then
		for i, claim in pairs( entity.claims[propertyId] ) do
			if ( claim.mainsnak and claim.mainsnak.datavalue ) then
				local datavalue = claim.mainsnak.datavalue;
				if ( datavalue.type == "string" and datavalue.value == value 
					or datavalue.type == "wikibase-entityid" and datavalue.value["entity-type"] == "item" and tostring( datavalue.value.id ) == value ) then
					table.insert( result, claim );
				end
			end
		end
	end
	return result;
end

function getBestStatements( entity, propertyId )
	local resultClaims = {};
	if ( entity and entity.claims and entity.claims[ propertyId ] ) then
		local rank = 'normal';
		for i, statement in pairs( entity.claims[ propertyId ] ) do
			if ( statement.rank == 'preferred' ) then
				rank = 'preferred';
				break;
			end
		end
		for i, statement in pairs( entity.claims[ propertyId ] ) do
			if ( statement.rank == rank ) then
				table.insert( resultClaims, statement );
			end
		end
	end
	return resultClaims;
end

function expandBookSeries( context, data )
	local bookSeries = data.bookSeries;
	if ( not bookSeries ) then return end;

	-- use only first one
	if ( type( bookSeries ) == 'table' and bookSeries[1] and bookSeries[1].id ) then
		data.bookSeries = bookSeries[1];
		bookSeries = data.bookSeries;
	end

	if ( not bookSeries ) then return end;
	if ( not bookSeries.id ) then return end;

	local bookSeriesEntity = getEntity( context, bookSeries.id );
	appendSnaks( bookSeriesEntity.claims, 'P123', data, 'publisher', {} );
	appendSnaks( bookSeriesEntity.claims, 'P291', data, 'place', {} );
	appendSnaks( bookSeriesEntity.claims, 'P236', data, 'issn', {} );
end

function expandPublication( context, sourceEntity, data )
	local publication = data.publication;

	-- use only first one
	if ( type( publication ) == 'table' and publication[1] and publication[1].id ) then
		data.publication = publication[1];
		publication = data.publication;
	end

	if ( not publication ) then return end;
	if ( not publication.id ) then return end;

	if ( sourceEntity ) then
		-- do we have appropriate record in P1433 ?
		local claims = findClaimsByValue( sourceEntity, 'P1433', publication.id );
		if ( claims and #claims ~= 0 ) then
			for _, claim in pairs( claims ) do
				populateDataFromClaims( context, sourceEntity, claim.qualifiers, data );
				break;
			end
		end
	end

	local titleWerePresent = not (not data.title);
	local pubEntity = getEntity( context, publication.id );
	populateSourceDataImpl( context, pubEntity, data );
	if ( titleWerePresent and isEmpty( data.publication.label ) ) then
		appendSnaks( pubEntity.claims, 'P1160', data, 'publication-title', {} ); -- obsolete
		data.publication.label = getSingle( data['publication-title'] );
	end
	if ( titleWerePresent and isEmpty( data.publication.label ) ) then
		appendSnaks( pubEntity.claims, 'P1476', data, 'publication-title', {} );
		appendSnaks( pubEntity.claims, 'P1680', data, 'publication-subtitle', {} );
		data.publication.label = getSingle( data['publication-title'] );
		data.publication.subtitle = getSingle( data['publication-subtitle'] );
	end
end

-- Expand special types of references when additional data could be found in OTHER entity properties
function expandSpecials( context, currentEntity, reference, data )
	local sourceId;
	if ( reference.snaks.P805
			and reference.snaks.P805[1]
			and reference.snaks.P805[1].datavalue
			and reference.snaks.P805[1].datavalue.value.id ) then
		sourceId = reference.snaks.P805[1].datavalue.value.id;
	elseif ( reference.snaks.P248
			and reference.snaks.P248[1]
			and reference.snaks.P248[1].datavalue
			and reference.snaks.P248[1].datavalue.value.id ) then
		sourceId = reference.snaks.P248[1].datavalue.value.id;
	end
	
	if sourceId then
		data.sourceId = sourceId;

		-- Gemeinsame Normdatei -- specified by P227
		if ( sourceId == 'Q36578' ) then
			appendSnaks( currentEntity.claims, 'P227', data, 'part', { format = function( gnd ) return 'Record #' .. gnd; end } );
			appendSnaks( currentEntity.claims, 'P227', data, 'url', { format = function( gnd ) return 'http://d-nb.info/gnd/' .. gnd .. '/'; end } );
			data.year = '2012—2016'
			expandSpecialsQualifiers( context, currentEntity, 'P227', data );

		-- BNF -- specified by P268
		elseif ( sourceId == 'Q15222191' ) then
			appendSnaks( currentEntity.claims, 'P268', data, 'part', { format = function( id ) return 'Record #' .. id; end } );
			appendSnaks( currentEntity.claims, 'P268', data, 'url', { format = function( id ) return 'http://catalogue.bnf.fr/ark:/12148/cb' .. id; end } );
			expandSpecialsQualifiers( context, currentEntity, 'P268', data );

		-- VIAF -- specified by P214
		elseif ( sourceId == 'Q54919' ) then
			appendSnaks( currentEntity.claims, 'P214', data, 'part', { format = function( id ) return 'Record #' .. id; end } );
			appendSnaks( currentEntity.claims, 'P214', data, 'url', { format = function( id ) return 'https://viaf.org/viaf/' .. id; end } );
			expandSpecialsQualifiers( context, currentEntity, 'P214', data );

		-- generic property search
		else
			local sourceEntity = getEntity( context, sourceId );
			if ( sourceEntity ) then
				for _, sourceClaim in ipairs( getBestStatements( sourceEntity, 'P1687' ) ) do
					if ( sourceClaim.mainsnak.snaktype == 'value' ) then
						local sourcePropertyId = sourceClaim.mainsnak.datavalue.value.id;
						local sourcePropertyEntity = getEntity( context, sourcePropertyId );
						if ( sourcePropertyEntity ) then
							for _, sourcePropertyClaim in ipairs( getBestStatements( sourcePropertyEntity, 'P1630' ) ) do
								if ( sourcePropertyClaim.mainsnak.snaktype == 'value' ) then
									appendSnaks( currentEntity.claims, sourcePropertyId, data, 'url', {
										format = function( id )
											return string.gsub( sourcePropertyClaim.mainsnak.datavalue.value, '$1', id );
										end;
									} );
									expandSpecialsQualifiers( context, currentEntity, sourcePropertyId, data );
									break;
								end
							end
						end
					end
				end
			end
		end

		-- do we have appropriate record in P1433 ?
		local claims = findClaimsByValue( currentEntity, 'P1343', sourceId );
		if ( claims and #claims ~= 0 ) then
			for _, claim in pairs( claims ) do
				populateDataFromClaims( context, sourceId, claim.qualifiers, data );
			end
		end
	end
end

function expandSpecialsQualifiers( context, entity, propertyId, data )
	if ( entity and entity.claims and entity.claims[propertyId] ) then
		for _, claim in pairs( entity.claims[propertyId] ) do
			populateDataFromClaims( context, nil, claim.qualifiers, data );
		end
	end
end

function isEmpty( str )
	return ( not str ) or ( str == nil ) or ( #str == 0 );
end

function isInstanceOf( entity, typeEntityId )
	if ( not entity or not entity.claims or not entity.claims.P31 ) then
		return false;
	end

	for _, claim in pairs( entity.claims.P31 ) do
		if ( claim and claim.mainsnak
				and claim.mainsnak.datavalue
				and claim.mainsnak.datavalue.value
				and claim.mainsnak.datavalue.value.id ) then
			local actualTypeId = claim.mainsnak.datavalue.value.id;
			if ( actualTypeId == typeEntityId ) then
				return true;
			end
		end
	end

	return false;
end

function getElementLink( context, entityId, entity )
	-- fast sitelink lookup, not an expensive operation
	local link = mw.wikibase.sitelink( entityId )
	if ( link ) then return ':' .. link end

	if ( not entity and entityId ) then
		entity = getEntity( context, entityId )
	end

	if ( entity ) then
		-- link to entity in source context language
		local projectToCheck = context.lang .. 'wiki';
		if ( entity.sitelinks and entity.sitelinks[ projectToCheck ] ) then
			return ':' .. context.lang .. ':' .. entity.sitelinks[ projectToCheck ].title;
		end
	end

	if ( entityId ) then return ':d:' .. entityId end;
	-- if ( entityId ) then return 'https://tools.wmflabs.org/reasonator/?q=' .. entityId .. '&lang=ru' end;
	return nil;
end

function getEntity( context, entityId )
	assertNotNull( 'context', context );
	assertNotNull( 'entityId', entityId );

	local cached = context.cache[ entityId ];
	if ( cached ) then
		return cached;
	end;

	local wbStatus, result = pcall( mw.wikibase.getEntity, entityId );
	if ( wbStatus ~= true ) then
		return nil;
	end
	
	if ( result ) then
		context.cache[ entityId ] = result;
	end

	return result;
end

function getNormativeTitle( entity )
	if ( not entity or not entity.claims or not entity.claims.P31 ) then
		return;
	end

	for _, claim in pairs( entity.claims.P31 ) do
		if ( claim and claim.mainsnak
				and claim.mainsnak.datavalue
				and claim.mainsnak.datavalue.value
				and claim.mainsnak.datavalue.value.id ) then
			local classId = claim.mainsnak.datavalue.value.id;
			local title = NORMATIVE_DOCUMENTS[ classId ];
			if ( title ) then
				return title;
			end
		end
	end

	return;
end

function getPlaceName( lang, placeId )
	-- ГОСТ Р 7.0.12—2011
	if ( lang == 'ru' ) then
		if ( placeId == 'Q649' ) then return toTextWithTip('М.', 'Москва'); end
		if ( placeId == 'Q656' ) then return toTextWithTip('СПб.', 'Санкт-Петербург'); end
		if ( placeId == 'Q891' ) then return toTextWithTip('Н. Новгород', 'Нижний Новгород'); end
		if ( placeId == 'Q908' ) then return toTextWithTip('Ростов н/Д.', 'Ростов-на-Дону'); end
	end
	return nil;
end

function getSingle( value )
	if ( not value ) then
		return;
	end
	if ( type( value ) == 'string' ) then
		return value;
	elseif ( type( value ) == 'table' ) then
		if ( value.id ) then
			return value.id;
		end

		for i, tableValue in pairs( value ) do
			return getSingle( tableValue );
		end
	end

	return '(unknown)';
end

function getSingleStringQualifierValue( allQualifiers, qualifierPropertyId )
	if ( not allQualifiers ) then return end
	if ( not allQualifiers[qualifierPropertyId] ) then return end

	for k, qualifier in pairs( allQualifiers[qualifierPropertyId] ) do
		if ( qualifier and qualifier.datatype == 'string'
				and qualifier.datavalue and qualifier.datavalue.type == 'string' and not isEmpty( qualifier.datavalue.value ) ) then
			return qualifier.datavalue.value;
		end
	end

	return;
end

function populateDataFromClaims( context, entityId, claims, data )
	appendSnaks( claims, 'P50', data, 'author', {} );
	appendSnaks( claims, 'P2093', data, 'author', {} );
	appendSnaks( claims, 'P407', data, 'lang', {} );
	appendSnaks( claims, 'P364', data, 'lang', {} );
	appendSnaks( claims, 'P958', data, 'part', {} );
	if ( not data.title ) then
		if ( not isEmpty( entityId ) ) then
			local optionsAsLinks = { format = function( text ) return { id = entityId, label = text } end };
			appendSnaks( claims, 'P1476', data, 'title', optionsAsLinks );
		else
			appendSnaks( claims, 'P1476', data, 'title', {} );
		end
		appendSnaks( claims, 'P1680', data, 'subtitle', {} );
	end
	appendSnaks( claims, 'P953', data, 'url', {} );
	appendSnaks( claims, 'P1065', data, 'url', {} );
	appendSnaks( claims, 'P854', data, 'url', {} );
	-- temp disable, use only for current entity, see Q22338048 for example of incorrect work
	-- appendSnaks( claims, 'P856', data, 'url', {} );

	appendSnaks( claims, 'P98', data, 'editor', {} );
	appendSnaks( claims, 'P655', data, 'translator', {} );

	appendSnaks( claims, 'P1433', data, 'publication', {} );
	appendSnaks( claims, 'P393', data, 'edition', {} );
	appendSnaks( claims, 'P123', data, 'publisher', {} );
	appendSnaks( claims, 'P291', data, 'place', {} );

	if ( claims and claims.P361 ) then
		for c, claim in pairs( claims.P361 ) do
			if ( claim and claim.mainsnak
					and claim.mainsnak.datavalue
					and claim.mainsnak.datavalue.value
					and claim.mainsnak.datavalue.value.id ) then
				local possibleBookSeriesEntityId = claim.mainsnak.datavalue.value.id;
				local possibleBookSeriesEntity = getEntity( context, possibleBookSeriesEntityId );
				if ( isInstanceOf( possibleBookSeriesEntity, 'Q277759' ) ) then
					appendImpl_toTable( data, 'bookSeries' );
					table.insert( data.bookSeries, { id = possibleBookSeriesEntityId } );

					appendQualifiers( { claim }, 'P478', data, 'bookSeriesVolume', {} );
					appendQualifiers( { claim }, 'P433', data, 'bookSeriesIssue', {} );
				end
			end
		end
	end

	appendSnaks( claims, 'P478', data, 'volume', {} );
	appendSnaks( claims, 'P433', data, 'issue', {} );
	appendSnaks( claims, 'P571', data, 'dateOfCreation', {} );
	appendSnaks( claims, 'P577', data, 'dateOfPublication', {} );
	appendSnaks( claims, 'P304', data, 'pages', {} );
	appendSnaks( claims, 'P1104', data, 'numberOfPages', {} );
	appendSnaks( claims, 'P1114', data, 'tirage', {} );
	appendSnaks( claims, 'P212', data, 'isbn', {} ); -- ISBN-13
	appendSnaks( claims, 'P957', data, 'isbn', {} ); -- ISBN-10
	appendSnaks( claims, 'P236', data, 'issn', {} );

    -- web
	-- appendSnaks( claims, 'P813', data, 'accessdate', {} );

    -- docs
	appendSnaks( claims, 'P1545', data, 'docNumber', {} );

	-- other
	appendSnaks( claims, 'P31', data, 'type', {} );

	appendSnaks( claims, 'P818', data, 'arxiv', {} );
	appendSnaks( claims, 'P356', data, 'doi', {} );
	appendSnaks( claims, 'P698', data, 'pmid', {} );

	-- JSTOR
	appendSnaks( claims, 'P888', data, 'url', { format = function( id ) return 'http://www.jstor.org/stable/' .. id end } );

	return src;
end

function populateSourceDataImpl( context, entity, plainData )
    local wsLink = mw.wikibase.getSitelink( entity.id, 'ruwikisource' );
    if ( wsLink ) then
       plainData.url = ":ru:s:" .. wsLink;
    end
	populateDataFromClaims( context, entity.id, entity.claims, plainData );

	local normativeTitle = getNormativeTitle( entity )
	if ( normativeTitle ) then
		local y, m, d = mw.ustring.match( getSingle( plainData.dateOfCreation ) , "(%-?%d+)%-(%d+)%-(%d+)T" );
		y,m,d = tonumber(y),tonumber(m),tonumber(d);
		local title = toString( { lang='ru' }, plainData.title, options_commas_nolinks );
		plainData.title = { normativeTitle .. " от&nbsp;" .. tostring(d) .. "&nbsp;" .. monthg[m]  .. " " .. tostring(y) .. "&nbsp;г. №&nbsp;" .. getSingle( plainData.docNumber ) .. ' «' .. title.. '»' }
	end

	if ( not plainData.title ) then
		if ( entity and entity.labels and entity.labels.ru and entity.labels.ru.value ) then
			plainData.title = { entity.labels.ru.value };
		end
	end

	return plainData;
end

function preprocessPlaces( data, lang )
	if ( not data.place ) then
		return;
	end;

	local newPlaces = {};
	for index, place in pairs( data.place ) do
		if ( place.id ) then
			local newPlaceStr = getPlaceName(lang, place.id)
			if ( newPlaceStr ) then
				newPlaces[index] = newPlaceStr;
			else
				newPlaces[index] = place;
			end
		else
			newPlaces[index] = place;
		end
	end
	data.place = newPlaces;
end

function renderLink( context, entityId, customTitle, options )
	if ( not entityId ) then error("entityId is not specified") end
	if ( type( entityId ) ~= 'string' ) then error('entityId is not string, but ' .. type( entityId ) ) end
	if ( type( customTitle or '' ) ~= 'string' ) then error('customTitle is not string, but ' .. type( customTitle ) ) end

	local title = customTitle;

	if ( isEmpty( title ) ) then
		local entity = getEntity( context, entityId );

		-- ISO 4
		if ( isEmpty( title ) ) then
			if ( entity and entity.claims and entity.claims.P1160 ) then
				for _, claim in pairs( entity.claims.P1160 ) do
					if ( claim
							and claim.mainsnak
							and claim.mainsnak.datavalue
							and claim.mainsnak.datavalue.value
							and claim.mainsnak.datavalue.value.language == context.lang ) then
						title = claim.mainsnak.datavalue.value.text;
						mw.log('Got title of ' .. entityId .. ' from ISO 4 claim: «' .. title .. '»' )
						break;
					end
				end
			end
		end

		-- official name P1448
		-- short name P1813
		if ( isEmpty( title ) and options.short ) then
			if ( entity and entity.claims and entity.claims.P1813 ) then
				for _, claim in pairs( entity.claims.P1813 ) do
					if ( claim
							and claim.mainsnak
							and claim.mainsnak.datavalue
							and claim.mainsnak.datavalue.value
							and claim.mainsnak.datavalue.value.language == context.lang ) then
						title = claim.mainsnak.datavalue.value.text;
						mw.log('Got title of ' .. entityId .. ' from short name claim: «' .. title .. '»' )
						break;
					end
				end
			end
		end
		-- person name P1559
		-- labels
		if ( isEmpty( title ) and entity.labels[ context.lang ] ) then
			title = entity.labels[ context.lang ].value;
			mw.log('Got title of ' .. entityId .. ' from label: «' .. title .. '»' )
		end
	end

	local actualText = title or '\'\'(untranslated)\'\'';
	local link = getElementLink( context, entityId, entity);
	return wrapInUrl( link, actualText );
end

function toTextWithTip( text, tip )
	return '<span title="' .. tip .. '" style="border-bottom: 1px dotted; cursor: help; white-space: nowrap">' .. text .. '</span>';
end

function toString( context, value, options )
	if ( type( value ) == 'string' ) then
		return options.format( value );
	elseif ( type( value ) == 'table' ) then
		if ( value.id ) then
			-- this is link
			if ( type( value.label or '' ) ~= 'string' ) then mw.logObject( value ); error('label of table value is not string but ' .. type( value.label ) ) end

			if ( options.preferids ) then
				return options.format( value.id );
			else
				if ( options.nolinks ) then
					return options.format( value.label or mw.wikibase.label( value.id ) or '\'\'(untranslated title)\'\'' );
				else
					return options.format( renderLink( context, value.id, value.label, options ) );
				end
			end
		end

		local resultList = {};
		for i, tableValue in pairs( value ) do
			table.insert( resultList, toString( context, tableValue, options ) );
		end

		return mw.text.listToText( resultList, options.separator, options.conjunction);
	else
		return options.format( '(unknown type)' );
	end

	return '';
end

function toStringSnak( propertyId, strValue )
	assertNotNull('propertyId', strValue)
	assertNotNull('strValue', strValue)

	local snak = { snaktype = "value", property = propertyId, datatype = 'string'};
	snak["datavalue"] = { value = strValue, type = 'string' };
	return snak;
end

function toUrlSnak( propertyId, strValue )
	assertNotNull('propertyId', strValue)
	assertNotNull('strValue', strValue)

	local snak = { snaktype = "value", property = propertyId, datatype = 'string'};
	snak["datavalue"] = { value = strValue, type = 'url' };
	return snak;
end

function toWikibaseEntityIdSnak( propertyId, entityId )
	assertNotNull('propertyId', entityId)
	assertNotNull('entityId', entityId)
	if ( mw.ustring.sub( entityId, 1, 1 ) ~= 'Q' ) then error( 'Incorrect entity ID: «' .. entityId .. '»' ); end;

	local value = {
		["entity-type"] = 'item',
		["id"] = entityId,
	};

	local snak = { snaktype = "value", property = propertyId, datatype = 'wikibase-item'};
	snak["datavalue"] = { value = value, type = 'wikibase-entityid' };
	return snak;
end

function wrapInUrl( urls, text )
	local url = getSingle( urls );
	if ( string.sub( url, 1, 1 ) == ':' ) then
		return '[[' .. url .. '|' .. text .. ']]';
	else
		return '[' .. url .. ' ' .. text .. ']';
	end
end

return p;