Modul:Wikidata

-- module local variables
local wiki =
{
	langcode = mw.language.getContentLanguage().code
}

-- internationalisation
local i18n =
{
	["errors"] =
	{
		["property-not-found"] = "Eigenschaft nicht gefunden.",
		["entity-not-found"] = "Wikidata-Eintrag nicht gefunden.",
		["entity-not-valid"] = "Die an die Wikidata-Schnittstelle übergebene Item-ID ist nicht gültig.",
		["unknown-claim-type"] = "Unbekannter Aussagentyp.",
		["unknown-entity-type"] = "Unbekannter Entity-Typ.",
		["qualifier-not-found"] = "Qualifikator nicht gefunden.",
		["site-not-found"] = "Wikimedia-Projekt nicht gefunden.",
		["invalid-parameters"] = "Ungültige Parameter.",
		["module-not-loaded"] = "Loading of additional module failed."
	},
	["maintenance-pages"] =
	{
		["entity-not-found"] = "Wikidata/Wartung/Fehlendes Datenobjekt",
		["entity-not-valid"] = "Wikidata/Wartung/Ungültige Datenobjekt-Identifikationsnummer",
		["property-not-existing"] = "Wikidata/Wartung/Eigenschaft existiert nicht"
	},
	["datetime"] =
	{
		-- $1 is a placeholder for the actual number
		[0] = "$1 Mrd. Jahren",		-- precision: billion years
		[1] = "$100 Mio. Jahren",	-- precision: hundred million years
		[2] = "$10 Mio. Jahren",	-- precision: ten million years
		[3] = "$1 Mio. Jahren",		-- precision: million years
		[4] = "$100.000 Jahren",	-- precision: hundred thousand years
		[5] = "$10.000 Jahren",		-- precision: ten thousand years
		[6] = "$1. Jahrtausend", 	-- precision: millenium
		[7] = "$1. Jahrhundert",	-- precision: century
		[8] = "$1er",				-- precision: decade
		-- the following use the format of #time parser function
		[9]  = "Y",					-- precision: year,
		[10] = "F Y",				-- precision: month
		[11] = "j. F Y",			-- precision: day
		[12] = 'j. F Y, G "Uhr"',	-- precision: hour
		[13] = "j. F Y G:i",		-- precision: minute
		[14] = "j. F Y G:i:s",		-- precision: second
		["beforenow"] = "vor $1",	-- how to format negative numbers for precisions 0 to 5
		["afternow"] = "in $1",		-- how to format positive numbers for precisions 0 to 5
		["bc"] = '$1 "v.Chr."',		-- how print negative years
		["ad"] = "$1"				-- how print positive years
	},
	["monolingualtext"] = '<span lang="%language">%text</span>',
	["FETCH_WIKIDATA"] = "ABFRAGE_WIKIDATA"
}

local numberIsParentCalls = 0 -- global value to count calls of expensive function isParent, including recursive calls

--important properties
local propertyId =
{
	["starttime"] = "P580",
	["endtime"] = "P582",
	["pointoftime"] = "P585"
}

local formatchar =
{
	[10] = {"n","m","M","F","xg"},				--precision: month
	[11] = {"W","j","d","z","D","l","N","w"},	--precision: day
	[12] = {"a","A","g","h","G","H"},			--precision: hour
	[13] = {"i"},								--precision: minute
	[14] = {"s","U"}							--precision: second
}

local function printError(code)
	return '<span class="error">' .. (i18n.errors[code] or code) .. '</span>'
end

-- the "qualifiers" and "snaks" field have a respective "qualifiers-order" and "snaks-order" field
-- use these as the second parameter and this function instead of the built-in "pairs" function
-- to iterate over all qualifiers and snaks in the intended order.
local function orderedpairs(array, order)
	if not order then return pairs(array) end

	-- return iterator function
	local i = 0
	return function()
		i = i + 1
		if order[i] then
			return order[i], array[order[i]]
		end
	end
end

-- Function to check whether a certain item is a parent of a given item.
-- If pExitItem is reached without finding the searched parent item, the search stops.
-- A parent is connected via P31 or P279.
-- Attention: very intensive function, use carefully!
local function isParent(pItem, pParent, pExitItem, pMaxDepth, pDepth)
	numberIsParentCalls = numberIsParentCalls + 1
	if not pDepth then pDepth = 0 end

	if type(pItem) == "number" then pItem = "Q" .. pItem end

	local entity = mw.wikibase.getEntity(pItem)
	if not entity then return false end

	local claims31
	local claims279
	if entity.claims then
		claims31 = entity.claims[mw.wikibase.resolvePropertyId('P31')]
		claims279 = entity.claims[mw.wikibase.resolvePropertyId('P279')]
	else
		return false
	end
	if not claims31 and not claims279 then return false end

	local parentIds = {}
	if claims31 and #claims31 > 0 then
		for i, v in ipairs(claims31) do parentIds[#parentIds+1] = getSnakValue(v.mainsnak, "numeric-id") end
	end
	if claims279 and #claims279 > 0 then
		for i, v in ipairs(claims279) do parentIds[#parentIds+1] = getSnakValue(v.mainsnak, "numeric-id") end
	end

	-- check if searched parent or exit item is reached or do recursive call
	if not parentIds[1] or #parentIds == 0 then return false end
	local itemString = ""
	local result = nil
	for i, v in ipairs(parentIds) do
		if not v then return false end
		itemString = "Q" .. v

		if itemString == pParent then
			-- successful!
			return true
		elseif itemString == pExitItem or itemString == "Q35120" then
			-- exit if either "exit item" or node item (Q35120) is reached
			return false
		else
			if pDepth+1 < pMaxDepth then
				result = isParent(itemString, pParent, pExitItem, pMaxDepth, pDepth+1)
			else return false end

			if result == true then return result end
		end
	end
	do return false end
end

local function printDatavalueCoordinate(data, parameter)
	-- data fields: latitude [double], longitude [double], altitude [double], precision [double], globe [wikidata URI, usually http://www.wikidata.org/entity/Q2 [earth]]
	if parameter then
		if parameter == "globe" then data.globe = mw.ustring.match(data.globe, "Q%d+") end -- extract entity id from the globe URI
		return data[parameter]
	else
		return data.latitude .. "/" .. data.longitude -- combine latitude and longitude, which can be decomposed using the #titleparts wiki function
	end
end

local function printDatavalueQuantity(data, parameter)
	-- data fields: amount [number], unit [string], upperBound [number], lowerBound [number]
	if not parameter or parameter == "amount" then
		return tonumber(data.amount)
	elseif parameter == "unit" then
		return mw.ustring.match(data.unit, "Q%d+")
	else
		return data[parameter]
	end
end

local function normalizeDate(date)
	date = mw.text.trim(date, "+")
	-- extract year
	local yearstr = mw.ustring.match(date, "^-?%d+")
	local year = tonumber(yearstr)
	-- remove leading zeros of year
	return year .. mw.ustring.sub(date, #yearstr + 1), year
end

-- precision: 0 - billion years, 1 - hundred million years, ..., 6 - millenia, 7 - century, 8 - decade, 9 - year, 10 - month, 11 - day, 12 - hour, 13 - minute, 14 - second
function formatDate(date, precision, timezone, formatstr)
	precision = precision or 11
	date, year = normalizeDate(date)
	date = string.gsub(date, "-00%f[%D]", "-01")
	if year == 0 and precision <= 9 then return "" end

	-- precision is 10000 years or more
	if precision <= 5 then
		local factor = 10 ^ ((5 - precision) + 4)
		local y2 = math.ceil(math.abs(year) / factor)
		local relative = mw.ustring.gsub(i18n.datetime[precision], "$1", tostring(y2))
		if year < 0 then
			relative = mw.ustring.gsub(i18n.datetime.beforenow, "$1", relative)
		else
			relative = mw.ustring.gsub(i18n.datetime.afternow, "$1", relative)
		end
		return relative
	end

	-- precision is decades, centuries and millenia
	local era
	if precision == 6 then era = mw.ustring.gsub(i18n.datetime[6], "$1", tostring(math.floor((math.abs(year) - 1) / 1000) + 1)) end
	if precision == 7 then era = mw.ustring.gsub(i18n.datetime[7], "$1", tostring(math.floor((math.abs(year) - 1) / 100) + 1)) end
	if precision == 8 then era = mw.ustring.gsub(i18n.datetime[8], "$1", tostring(math.floor(math.abs(year) / 10) * 10)) end
	if era then
		if year < 0 then era = mw.ustring.gsub(mw.ustring.gsub(i18n.datetime.bc, '"', ""), "$1", era)
		elseif year > 0 then era = mw.ustring.gsub(mw.ustring.gsub(i18n.datetime.ad, '"', ""), "$1", era) end
		return era
	end

	-- precision is years or less
	if precision >= 9 then
		--[[ the following code replaces the UTC suffix with the given negated timezone to convert the global time to the given local time
		timezone = tonumber(timezone)
		if timezone and timezone ~= 0 then
			timezone = -timezone
			timezone = string.format("%.2d%.2d", timezone / 60, timezone % 60)
			if timezone[1] ~= '-' then timezone = "+" .. timezone end
			date = mw.text.trim(date, "Z") .. " " .. timezone
		end
		]]--
		if formatstr then
			for i=(precision+1), 14 do
				for _, ch in pairs(formatchar[i]) do
					if formatstr:find(ch) then
						formatstr = i18n.datetime[precision]
					end
				end
			end
		else
			formatstr = i18n.datetime[precision]
		end
		if year == 0 then formatstr = mw.ustring.gsub(formatstr, i18n.datetime[9], "")
		elseif year < 0 then
			-- Mediawiki formatDate doesn't support negative years
			date = mw.ustring.sub(date, 2)
			formatstr = mw.ustring.gsub(formatstr, i18n.datetime[9], mw.ustring.gsub(i18n.datetime.bc, "$1", i18n.datetime[9]))
		elseif year > 0 and i18n.datetime.ad ~= "$1" then
			formatstr = mw.ustring.gsub(formatstr, i18n.datetime[9], mw.ustring.gsub(i18n.datetime.ad, "$1", i18n.datetime[9]))
		end
		return mw.language.new(wiki.langcode):formatDate(formatstr, date)
	end
end

local function printDatavalueTime(data, parameter)
	-- data fields: time [ISO 8601 time], timezone [int in minutes], before [int], after [int], precision [int], calendarmodel [wikidata URI]
	--   precision: 0 - billion years, 1 - hundred million years, ..., 6 - millenia, 7 - century, 8 - decade, 9 - year, 10 - month, 11 - day, 12 - hour, 13 - minute, 14 - second
	--   calendarmodel: e.g. http://www.wikidata.org/entity/Q1985727 for the proleptic Gregorian calendar or http://www.wikidata.org/wiki/Q11184 for the Julian calendar]
	if parameter then
		local para, formatstr = parameter:match("([^:]+):([^:]+)")
		if parameter == "calendarmodel" then
			data.calendarmodel = string.match(data.calendarmodel, "Q%d+") -- extract entity id from the calendar model URI
		elseif para and para == "time" then
			return formatDate(data.time, data.precision, data.timezone,formatstr)
		elseif parameter == "time" then
			data.time = normalizeDate(data.time)
		end
		return data[parameter]
	else
		return formatDate(data.time, data.precision, data.timezone)
	end
end

local function printDatavalueEntity(data, parameter)
	-- data fields: entity-type [string], numeric-id [int, Wikidata id]
	local id

	if data["entity-type"] == "item" then id = "Q" .. data["numeric-id"]
	elseif data["entity-type"] == "property" then id = "P" .. data["numeric-id"]
	else return printError("unknown-entity-type")
	end

	if parameter then
		if parameter == "link" then
			local linkTarget = mw.wikibase.sitelink(id)
			local linkName = mw.wikibase.label(id)
			if linkTarget then
				local link = linkTarget
				-- if there is a local Wikipedia article linking to it, use the label or the article title
				if linkName and (linkName ~= linkTarget) then link = link .. "|" .. linkName end
				return "[[" .. link .. "]]"
			else
				-- if there is no local Wikipedia article output the label or link to the Wikidata object to input a proper label
				if linkName then return linkName else return "[[:d:" .. id .. "|" .. id .. "]]" end
			end
		else
			return data[parameter]
		end
	else
		return mw.wikibase.label(id) or id
	end
end

local function printDatavalueMonolingualText(data, parameter)
	-- data fields: language [string], text [string]
	if parameter then
		return data[parameter]
	else
		local result = mw.ustring.gsub(mw.ustring.gsub(i18n.monolingualtext, "%%language", data["language"]), "%%text", data["text"])
		return result
	end
end

function getSnakValue(snak, parameter)
	-- snaks have three types: "novalue" for null/nil, "somevalue" for not null/not nil, or "value" for actual data
	if snak.snaktype == "value" then
		-- call the respective snak parser
		if snak.datavalue.type == "string" then return snak.datavalue.value
		elseif snak.datavalue.type == "globecoordinate" then return printDatavalueCoordinate(snak.datavalue.value, parameter)
		elseif snak.datavalue.type == "quantity" then return printDatavalueQuantity(snak.datavalue.value, parameter)
		elseif snak.datavalue.type == "time" then return printDatavalueTime(snak.datavalue.value, parameter)
		elseif snak.datavalue.type == "wikibase-entityid" then return printDatavalueEntity(snak.datavalue.value, parameter)
		elseif snak.datavalue.type == "monolingualtext" then return printDatavalueMonolingualText(snak.datavalue.value, parameter)
		end
	end
	return mw.wikibase.renderSnak(snak)
end

function getQualifierSnak(claim, qualifierId)
	-- a "snak" is Wikidata terminology for a typed key/value pair
	-- a claim consists of a main snak holding the main information of this claim,
	-- as well as a list of attribute snaks and a list of references snaks
	if qualifierId then
		-- search the attribute snak with the given qualifier as key
		if claim and claim.qualifiers then
			local qualifier = claim.qualifiers[qualifierId]
			if qualifier then return qualifier[1] end
		end
		return nil, printError("qualifier-not-found")
	else
		-- otherwise return the main snak
		return claim.mainsnak
	end
end

local function datavalueTimeToDateObject(data)
	local sign, year, month, day, hour, minute, second = string.match(data.time, "(.)(%d+)%-(%d+)%-(%d+)T(%d+):(%d+):(%d+)Z")
	local result =
	{
		year = tonumber(year),
		month = tonumber(month),
		day = tonumber(day),
		hour = tonumber(hour),
		min = tonumber(minute),
		sec = tonumber(second),
		timezone = data.timezone,
		julian = data.calendarmodel and string.match(data.calendarmodel, "Q11184$")
	}
	if sign == "-" then result.year = -result.year end
	return result
end

function julianDay(dateObject)
	local year = dateObject.year
	local month = dateObject.month or 0
	local day = dateObject.day or 0

	if month == 0 then month = 1 end
	if day == 0 then day = 1 end
	if month <= 2 then
		year = year - 1
		month = month + 12
	end

	local time = ((((dateObject.sec or 0) / 60 + (dateObject.min or 0) + (dateObject.timezone or 0)) / 60) + (dateObject.hour or 0)) / 24

	local b
	if dateObject.julian then b = 0 else
		local century = math.floor(year / 100)
		b = 2 - century + math.floor(century / 4)
	end

	return math.floor(365.25 * (year + 4716)) + math.floor(30.6001 * (month + 1)) + day + time + b - 1524.5
end

function getQualifierSortValue(claim, qualifierId)
	local snak = getQualifierSnak(claim, qualifierId)
	if snak and snak.snaktype == "value" then
		if snak.datavalue.type == "time" then
			return julianDay(datavalueTimeToDateObject(snak.datavalue.value))
		else
			return getSnakValue(snak)
		end
	end
end

function getValueOfClaim(claim, qualifierId, parameter)
	local error
	local snak
	snak, error = getQualifierSnak(claim, qualifierId)
	if snak then
		return getSnakValue(snak, parameter)
	else
		return nil, error
	end
end


function formatReference(ref)
	-- "imported from"-references are useless, skip them:
	if ref["P143"] or ref["P4656"] then return nil end
	
	-- load [[Modul:Zitation]]
	local ZitationSuccess, r = pcall(require, "Modul:Zitation")
	if type(r) == "table" then
		Zitation = r.Zitation()
		-- clear Zitation state from previous invocations
		Zitation.o = nil
	end
	-- assert (ZitationSuccess, i18n["errors"]["module-not-loaded"])
	
	-- assignments of Wikidata properties to Zitation parameters
	local wdZmap = {
		P1433 = {"bas", "Werk"},
		P248  = {"bas", "Werk"},
		P1476 = {"bas", "Titel"},
		P1680 = {"bas", "TitelErg"},
		P407  = {"bas", "Sprache"},
		P364  = {"bas", "Sprache"},
		P2439 = {"bas", "Sprache"},
		P123  = {"bas", "Verlag"},
		P577  = {"bas", "Datum"},
		P98   = {"bas", "Hrsg"},
		P2093 = {"bas", "Autor"},
		P50   = {"bas", "Autor"},
		P1683 = {"bas", "Zitat"},
		P854  = {"www", "URL"},
		P813  = {"www", "Abruf"},
		P1065 = {"www", "ArchivURL"},
		P2960 = {"www", "ArchivDatum"},
		P2701 = {"www", "Format"},
		P393  = {"print", "Auflage"},
		P291  = {"print", "Ort"},
		P304  = {"fragment", "Seiten"},
		P792  = {"fragment", "Kapitel"},
		P629  = {"orig", "Titel"}
	}
	
	for prop, value in pairs(ref) do
		if wdZmap[prop] then
			if type(value) == "table" then
				-- More snaks with same property, we concatenate using a comma
				value = table.concat(value, ", ")
			end
			-- value should be string now, so we can call Zitation
			if type(value) == "string" and string.len(value) > 0 then
				Zitation.fill(wdZmap[prop][1], wdZmap[prop][2], value, prop)	
			end
		end
	end
	-- if no title on Wikidata, try to use the URL as title
	if (not ref["P1476"]) and ref["P854"] then
		local URLutil = Zitation.fetch("URLutil")
		Zitation.fill("bas", "Titel", URLutil.getHost(ref["P854"]))
	end
	return Zitation.format()
end

function getReferences(frame, claim)
	local result = ""
	-- traverse through all references
	for ref in pairs(claim.references or {}) do
		local refTable = {}
		for snakkey, snakval in orderedpairs(claim.references[ref].snaks or {}, claim.references[ref]["snaks-order"]) do
			if #snakval == 1 then
				refTable[snakkey] = getSnakValue(snakval[1])
			else
				--
				local multival = {}
				for snakidx = 1, #snakval do
						table.insert(multival, getSnakValue(snakval[snakidx]))
				end
				refTable[snakkey] = multival
			end
		end
		
		local formattedRef, f = formatReference(refTable)
		
		if formattedRef and formattedRef ~= "" then
			local hash = mw.hash.hashValue('fnv164', formattedRef)
			result = result .. frame:extensionTag("ref", formattedRef, { name = '_' .. hash })
		end
	end
	return result
end

local function hasqualifier(claim, qualifierproperty)
	local invert
	if string.sub(qualifierproperty, 1, 1) == "!" then invert = true else invert = false end
	if not claim.qualifiers and not invert then return false end
	if not claim.qualifiers and invert then return true end
	if qualifierproperty == '' then return true end
	if not invert and not claim.qualifiers[qualifierproperty] then return false end
	if invert and claim.qualifiers[string.sub(qualifierproperty, 2)] then return false end
	return true
end

local function qualifierhasvalue(claim, property, value)
	if not claim.qualifiers then return false end
	if not claim.qualifiers[property] then return false end
	for key, snak in pairs(claim.qualifiers[property]) do
		if snak.snaktype == "value" then
			if snak.datavalue.type == "wikibase-entityid" then
				if snak.datavalue.value.id == value then
					return true
				end
			--TODO: elseif other types
			end
		end
	end
	return false
end

local function hassource(claim, sourceproperty)
	if not claim.references then return false end
	if sourceproperty == '' or sourceproperty == "true" then return true end
	if string.sub(sourceproperty,1,1) ~= "!" then
		for _, source in pairs(claim.references) do
			if source.snaks[sourceproperty] then return true end
		end
		return false
	else
		for _, source in pairs(claim.references) do
			for key in pairs(source.snaks) do
				if key ~= string.sub(sourceproperty,2) then return true end
			end
		end
		return false
	end
end

function atdate(claim, mydate)
	local refdate, mydateyear
	if not mydate or mydate == "" then
		refdate = os.date("!*t")
	else
		if string.match(mydate, "^%d+$") then
			refdate = { year = tonumber(mydate) }
			mydateyear = tonumber(mydate)
		else
			refdate = datavalueTimeToDateObject({ time = mw.language.getContentLanguage():formatDate("+Y-m-d\\TH:i:s\\Z", mydate) })
			mydateyear = 0
		end
	end
	local refjd = julianDay(refdate)
	local exactdate = getQualifierSortValue(claim, propertyId["pointoftime"])
	local mindate = getQualifierSortValue(claim, propertyId["starttime"])
	local maxdate = getQualifierSortValue(claim, propertyId["endtime"])
	
	if exactdate then
		-- if there is an exact date in the qualifier, and the atdate parameter is on year precision, mindate is the beginning of the year and maxdate is 31st Dec of that particular year
		local refmaxjd
		if mydateyear > 0 then
			refmaxjd = julianDay({ year = tonumber(mydate), month=12, day=31 })
		else 
			refmaxjd = refjd
		end
		if exactdate < refjd or exactdate > refmaxjd then return false end
	else 
		if mindate and mindate > refjd then return false end
		if maxdate and maxdate < refjd then return false end
	end

	return true -- success, the claim was valid at "mydate"
end

local function notdeprecated(claim)
  return claim.rank ~= "deprecated"
end

--returns a table of claims excluding claims not passed the filters
function filterClaims(frame, claims)
	local function filter(condition, filterfunction)
		if not frame.args[condition] then
			return
		end
		local newclaims = {}
		for i, claim in pairs(claims) do
			if filterfunction(claim, frame.args[condition]) then
				table.insert(newclaims, claim)
			end
		end
		claims = newclaims
	end

	filter('hasqualifier', hasqualifier)
	filter('hassource', hassource)
	filter('atdate', atdate)
	if not frame.args.includedeprecated then
		frame.args.notdeprecated = true
    	filter('notdeprecated', notdeprecated)
    end
	
	-- use additional unnamed parameters as qualifier conditions (in pairs)
	for key in pairs(frame.args) do
		if type(key) == "number" and key > 2 and key % 2 == 1 then
			-- key = 3, 5, 7 and so on
			local newclaims = {}
			local values = frame.args[key]
			local negated = string.sub(values, 1, 1) == "!"
			if negated then values = string.sub(values, 2) end
			for i, claim in pairs(claims) do
				local hasvalue = false
				for val in mw.text.gsplit(values, ",") do
					if qualifierhasvalue(claim, frame.args[key - 1], val) then
						hasvalue = true
						break
					end
				end
				if hasvalue ~= negated then table.insert(newclaims, claim) end
			end
			claims = newclaims
		end
	end
	
	return claims
end

local p = {}

function p.isSubclass(frame)
	if not frame.args["parent"] then return "" end

	local maxDepth
	maxDepth = tonumber(frame.args["maxDepth"]) or 5

	local result
	if frame.args["id"] == frame.args["parent"] then 
		result = true 
	else
		result = isParent(frame.args["id"], frame.args["parent"], frame.args["exitItem"], maxDepth)
	end
	
	-- mw.log(numberIsParentCalls) --uncomment to load number of isParent() calls into log
	
	if frame.args["returnInt"] then
		if result == true then return 1 else return "" end
	else
		if result then return result else return false end
	end
	
end

function p.descriptionIn(frame)
	local langcode = frame.args[1]
	local id = frame.args[2]
	-- return description of a Wikidata entity in the given language or the default language of this Wikipedia site
	local entity = mw.wikibase.getEntity(id)
	if entity and entity.descriptions then
		local desc = entity.descriptions[langcode or wiki.langcode]
		if desc then return desc.value end
	else
		return "";
	end
end

function p.labelIn(frame)
	local langcode = frame.args[1]
	local id = frame.args[2]
	-- return label of a Wikidata entity in the given language or the default language of this Wikipedia site
	local entity = mw.wikibase.getEntity(id)
	if entity and entity.labels then
		local label = entity.labels[langcode or wiki.langcode]
		if label then return label.value end
	else
		return "";
	end
end

function p.claim(frame)
	local property = frame.args[1] or ""
	local id = frame.args["id"]
	local qualifierId = frame.args["qualifier"]
	local parameter = frame.args["parameter"]
	local language = frame.args["language"]
	local list = frame.args["list"]
	local includeempty = frame.args["includeempty"]
	local listMaxItems = tonumber(frame.args["listMaxItems"]) or 0
	local references = frame.args["references"]
	local sort = frame.args["sort"]
	local sortEmptiesFirst = frame.args["sortEmptiesFirst"]
	local sortInItem = frame.args["sortInItem"]
	local inverse = frame.args["inverse"]
	local showerrors = frame.args["showerrors"]
	local default = frame.args["default"]
	if default then showerrors = nil end

	-- get wikidata entity
	if id then
		if not mw.wikibase.isValidEntityId(id) then
			if showerrors then 
				return printError("entity-not-valid") 
			else 
				local temp = mw.title.new(i18n["maintenance-pages"]["entity-not-valid"], "Modul").exists
				return default 
			end
		elseif not mw.wikibase.entityExists(id) then
			if showerrors then
				return printError("entity-not-found") 
			else 
				local temp = mw.title.new(i18n["maintenance-pages"]["entity-not-found"], "Modul").exists
				return default 
			end
		end
	end
	
	local entity = mw.wikibase.getEntity(id)
	if not entity then
		if showerrors then return printError("entity-not-found") else return default end
	end

	-- check if property exists
	local realProp = mw.wikibase.resolvePropertyId(property)
	if not realProp then
		local temp = mw.title.new(i18n["maintenance-pages"]["property-not-existing"], "Modul").exists
	end

	-- fetch the first claim of satisfying the given property
	local claims
	if entity.claims then claims = entity.claims[realProp] end
	if not claims or not claims[1] then
		if showerrors then return printError("property-not-found") else return default end
	end

	--filter claims
	claims = filterClaims(frame, claims)
	if not claims[1] then return default end

	-- get initial sort indices
	local sortindices = {}
	for idx in pairs(claims) do
		sortindices[#sortindices + 1] = idx
	end

	local comparator
	if sort then
		comparator = function(a, b) --comparator function for sorting statements based on qualifier value
			-- load qualifier values
			local QualifierSortValueA = getQualifierSortValue(claims[a], sort)
			local QualifierSortValueB = getQualifierSortValue(claims[b], sort)
			
			-- if either of the two statements does not have this qualifer: 
			---- if sortEmptiesFirst=true: sort it to the beginning 
			---- else: always sort it to the end
			if not QualifierSortValueB then 
				if not QualifierSortValueA then
					-- if neither of the two statements has this qualifier, arbitrarily but consistently return a < b
					return a < b
				elseif sortEmptiesFirst then
					return false
				else
					return true
				end
			elseif not QualifierSortValueA then 
				if sortEmptiesFirst then return true else return false end
			end
			
			if type(QualifierSortValueA) ~= type(QualifierSortValueB) and not (tonumber(QualifierSortValueA) and tonumber(QualifierSortValueB)) then
				if tonumber(QualifierSortValueA) then return true
				elseif tonumber(QualifierSortValueB) then return false
				elseif tostring(QualifierSortValueA) and tostring(QualifierSortValueB) then
					if inverse then return tostring(QualifierSortValueA) > tostring(QualifierSortValueB) else return tostring(QualifierSortValueA) < tostring(QualifierSortValueB) end
				else return false end -- different types, neither numbers nor strings, no chance to compare => random result to avoid script error
			elseif tonumber(QualifierSortValueA) and tonumber(QualifierSortValueB) then
				QualifierSortValueA = tonumber(QualifierSortValueA)
				QualifierSortValueB = tonumber(QualifierSortValueB)
			end
			if inverse then
				return QualifierSortValueA > QualifierSortValueB
			else
				return QualifierSortValueA < QualifierSortValueB
			end
		end
	elseif sortInItem then
		-- fill table sortkeys
		local sortkeys = {}
		local snakSingle
		local sortkeyValueId
		local claimContainingValue
		for idx, claim in pairs(claims) do
			snakSingle = getQualifierSnak(claim)
			sortkeyValueId = "Q" .. getSnakValue(snakSingle, "numeric-id")
			claimContainingValue = mw.wikibase.getEntity(sortkeyValueId).claims[mw.wikibase.resolvePropertyId(sortInItem)]
			if claimContainingValue then
				sortkeys[#sortkeys + 1] = getValueOfClaim(claimContainingValue[1])
			else
				sortkeys[#sortkeys + 1] = ""
			end
		end
		comparator = function(a, b)
			if inverse then
				return sortkeys[a] > sortkeys [b]
			else
				return sortkeys[a] < sortkeys [b]
			end
		end
	else
		-- sort by claim rank
		comparator = function(a, b)
			local rankmap = { deprecated = 2, normal = 1, preferred = 0 }
			local ranka = rankmap[claims[a].rank or "normal"] ..  string.format("%08d", a)
			local rankb = rankmap[claims[b].rank or "normal"] ..  string.format("%08d", b)
			return ranka < rankb
		end
	end
	table.sort(sortindices, comparator)

	local result
	local error
	if list then
		list = string.gsub(list, "\\n", "\n") -- if a newline is provided (whose backslash will be escaped) unescape it
		local value
		-- iterate over all elements and return their value (if existing)
		result = {}
		for idx in pairs(claims) do
			local claim = claims[sortindices[idx]]
			value, error =  getValueOfClaim(claim, qualifierId, parameter)
			if not value and value ~= 0 and showerrors then value = error end
			if not value and value ~= 0 and includeempty then value = "" end
			if value and references then value = value .. getReferences(frame, claim) end
			result[#result + 1] = value
		end
		if listMaxItems and listMaxItems > 0 then
			result = table.concat(result, list, 1, math.min(#result, listMaxItems))
		else
			result = table.concat(result, list)
		end
	else
		-- return first element

		local claim = claims[sortindices[1]]
		if language == "Q" then
			result, error = "Q" .. getSnakValue(getQualifierSnak(claim), "numeric-id")
		elseif language and claim.mainsnak.datatype == "monolingualtext" then
			-- iterate over claims to find adequate language
			for idx, claim in pairs(claims) do
				if claim.mainsnak.datavalue.value.language == language then
					result, error = getValueOfClaim(claim, qualifierId, parameter)
					break
				end
			end
		else
			result, error = getValueOfClaim(claim, qualifierId, parameter)
		end
		if references == "only" then 
			result = getReferences(frame, claim)
		elseif result and references then 
			result = result .. getReferences(frame, claim) 
		end
	end

	if result then return result else
		if showerrors then return error else return default end
	end
end

function p.getValue(frame)
	local param = frame.args[2]
	if param == "FETCH_WIKIDATA" or param == i18n["FETCH_WIKIDATA"] then return p.claim(frame) else return param end
end

function p.pageId(frame)
	local id = frame.args[1]
	local entity = mw.wikibase.getEntity(id)
	if not entity then return "" else return entity.id end
end

function p.labelOf(frame)
	local id = frame.args[1]
	-- returns the label of the given entity/property id
	-- if no id is given, the one from the entity associated with the calling Wikipedia article is used
	if not id then
		local entity = mw.wikibase.getEntity()
		if not entity then return printError("entity-not-found") end
		id = entity.id
	end
	return mw.wikibase.label(id)
end

function p.sitelinkOf(frame)
	local id = frame.args[1]
	-- returns the Wikipedia article name of the given entity
	-- if no id is given, the one from the entity associated with the calling Wikipedia article is used
	if not id then
		local entity = mw.wikibase.getEntity()
		if not entity then return printError("entity-not-found") end
		id = entity.id
	end
	return mw.wikibase.sitelink(id)
end

function p.badges(frame)
	local site = frame.args[1]
	local id = frame.args[2]
	if not site then return printError("site-not-found") end
	local entity = mw.wikibase.getEntity(id)
	if not entity then return printError("entity-not-found") end
	local badges = entity.sitelinks[site].badges
	if badges then
		local result
		for idx = 1, #badges do
			if result then result = result .. "/" .. badges[idx] else result = badges[idx] end
		end
		return result
	end
end

function p.sitelinkCount(frame)
	local filter = "^.*" .. (frame.args[1] or "") .. "$"
	local id = frame.args[2]

	local entity = mw.wikibase.getEntity(id)
	local count = 0
	if entity and entity.sitelinks then
		for project, _ in pairs(entity.sitelinks) do
			if string.find(project, filter) then count = count + 1 end
		end
	end
	return count
end

-- call this in cases of script errors within a function instead of {{#invoke:Wikidata|<method>|...}} call {{#invoke:Wikidata|debug|<method>|...}}
function p.debug(frame)
	local func = frame.args[1]
	if func then
		-- create new parameter set, where the first parameter with the function name is removed
		local newargs = {}
		for key, val in pairs(frame.args) do
			if type(key) == "number" then
				if key > 1 then newargs[key - 1] = val end
			else
				newargs[key] = val
			end
		end
		frame.args = newargs
		local status, result = pcall(p[func], frame)
		-- if status then return tostring(result) or "" else return '<span class="error">' .. result .. '</span>' end -- revert
		if status then return result else return '<span class="error">' .. result .. '</span>' end
	else
		return printError("invalid-parameters")
	end
end

function p.printEntity(frame)
	local id = frame.args[1]
	local entity = mw.wikibase.getEntity(id)
	if entity then return "<pre>" .. mw.text.jsonEncode(entity, mw.text.JSON_PRETTY) .. "</pre>" end
end

-- formfill Template:Coordinate (NS, EW, name from WikidataEntity) and expand it
-- füllt Vorlage:Coordinate (NS, EW, name mit Wikidata-Werten) + expandiert sie
--  1st frame.arg                            .. Q prefixed entity id (mandatory)
--  named frame.arg "type", "region", "text" .. see doc of 'Coordinate' template
function p.ffCoordinate(frame)
	local f = frame
	local id = f.args[1] or f.args.Q
	local name = f.args.name or p.labelIn{ args = { nil, id, id = id }}
	
	local coord = mw.text.split(p.claim{ args = { "P625", id, id = id }}, '/')
	coord[1] = tonumber(coord[1])
	coord[2] = tonumber(coord[2])

	local t, r = f.args.type, f.args.region
	if not t
	then t = p.claim{ args = { "P31", id, id = id, language = "Q" }}
		 t = t and t:gsub("Q.*", {
			Q8502  = "mountain",
			Q54050 = "landmark"
		 })
		 if not t or t and t:find("Q", 1, true)
		 then t="" -- no default, let Coordinate warn about unset type= param
		 end
	end
	if not r
	then r = p.claim{ args = { "P17", id, id = id, language = "Q" }}
		 r = r and p.claim{ args = { "P297", r, id = r }}
		 if not r
		 then r="" -- no default, let Coordinate warn about unset region= param
		 end
	end
	
	return ('<span data-sort-value="%010.6f"></span>'):format((f.args.sortkey
		or "EW"):find("EW", 1, true) and coord[2]+360.0 or coord[1]+180.0
	) .. f:expandTemplate{ title = 'Coordinate', args = {
		NS = coord[1], EW = coord[2], type = t, region = r,
		text = f.args.text or (f.args.maplink and "ICON0" or "/"),
		name = name, simple = f.args.simple
	}} .. (not f.args.maplink and "" or (" " ..
		--f:callParserFunction{ name="#statements", args={ "P625", from = id } }
		f:callParserFunction{ name="#tag:maplink", args={ "",
			class = "no-icon", text = f.args.mlname and name,
			zoom = 12, latitude = coord[1], longitude = coord[2]
		}}
	))
end

function p.ffCoordinateAndLatLonMaplink(frame)
	frame.args.maplink = 1
	--frame.args.mlname = nil
	return p.ffCoordinate(frame)
end

function p.ffCoordinateAndMaplink(frame)
	frame.args.maplink = 1
	frame.args.mlname = 1
	return p.ffCoordinate(frame)
end


return p