Module:Wd

Documentation for this module may be created at Module:Wd/doc

local p = {}

local aliasesP = {
	coord           = "P625",
	
	author          = "P50",
	publisher       = "P123",
	importedFrom    = "P143",
	statedIn        = "P248",
	publicationDate = "P577",
	startTime       = "P580",
	endTime         = "P582",
	retrieved       = "P813",
	referenceURL    = "P854",
	archiveURL      = "P1065",
	title           = "P1476",
	quote           = "P1683",
	shortName       = "P1813",
	language        = "P2439",
	archiveDate     = "P2960"
}

local aliasesQ = {
	percentage              = "Q11229",
	prolepticJulianCalendar = "Q1985786"
}

local parameters = {
	property  = "%p",
	qualifier = "%q",
	reference = "%r",
	separator = "%s"
}

local formats = {
	property              = "%p[%s][%r]",
	qualifier             = "%q[%s][%r]",
	reference             = "%r",
	propertyWithQualifier = "%p[ <span style=\"font-size:smaller\">(%q)</span>][%s][%r]"
}

local hookNames = {
	                      -- {level_1, level_2}
	[parameters.property]  = {"getProperty"},
	[parameters.qualifier] = {"getQualifiers", "getQualifier"},
	[parameters.reference] = {"getReferences", "getReference"}
}

local Config = {}
Config.__index = Config

-- allows for recursive calls
function Config.new()
	local cfg = {}
	setmetatable(cfg, Config)
	
	cfg.separators = {
		-- use tables so that we can pass by reference
		["sep"]   = {" "},
		["sep%s"] = {","},
		["sep%q"] = {", "},
		["sep%r"] = {""},
		["punc"] = {""}
	}
	
	cfg.entity = nil
	cfg.propertyID = nil
	cfg.propertyValue = nil
	cfg.qualifierID = nil
	
	cfg.bestRank = true
	cfg.ranks = {true, true, false}  -- preferred = true, normal = true, deprecated = false
	cfg.foundRank = #cfg.ranks
	cfg.flagBest = false
	cfg.flagRank = false
	
	cfg.periods = {true, true, true}  -- future = true, current = true, former = true
	cfg.flagPeriod = false
	
	cfg.mdyDate = false
	
	cfg.pageTitle = false
	
	cfg.langCode = mw.language.getContentLanguage().code
	cfg.langName = mw.language.fetchLanguageName(cfg.langCode, cfg.langCode)
	cfg.langObj = mw.language.new(cfg.langCode)
	
	cfg.states = {}
	cfg.curState = nil
	
	return cfg
end

local State = {}
State.__index = State

function State.new(cfg)
	local stt = {}
	setmetatable(stt, State)
	
	stt.conf = cfg
	
	stt.outPreferred = {}
	stt.outNormal = {}
	stt.outDeprecated = {}
	
	stt.parsedFormat = {}
	stt.separator = {}
	stt.movSeparator = {}
	stt.puncMark = {}
	
	stt.linked = false
	stt.rawValue = false
	stt.shortName = false
	stt.singleValue = false
	
	return stt
end

function unknownDataTypeError(dataType)
	return "Unknown or unsupported datatype '" .. dataType .. "'"
end

function missingRequiredParameterError()
	return "No required parameters defined, needing at least one"
end

function extraRequiredParameterError(param)
	return "Parameter '" .. param .. "' must be defined as optional"
end

function parseWikidataURL(url)
	local i, j
	
	if url:match('^http[s]?://') then
		i, j = url:find("Q")
		
		if i then
			return url:sub(i)
		end
	end
	
	return nil
end

function parseDate(dateStr, precision)
	precision = precision or "d"
	local i, j, index, ptr
	local parts = {nil, nil, nil}
	
	if dateStr == nil then
		return parts[1], parts[2], parts[3]  -- year, month, day
	end
	
	-- 'T' for snak values, '/' for outputs with '/Julian' attached
	i, j = dateStr:find("[T/]")
	
	if i then
		dateStr = dateStr:sub(1, i-1)
	end
	
	local from = 1
	
	if dateStr:sub(1,1) == "-" then
		-- this is a negative number, look further ahead
		from = 2
	end
	
	index = 1
	ptr = 1
	
	i, j = dateStr:find("-", from)
	
	if i then
		-- year
		parts[index] = tonumber(mw.ustring.gsub(dateStr:sub(ptr, i-1), "^\+(.+)$", "%1"), 10)  -- remove + sign
		
		if parts[index] == -0 then
			parts[index] = 0
		end
		
		if precision == "y" then
			-- we're done
			return parts[1], parts[2], parts[3]  -- year, month, day
		end
		
		index = index + 1
		ptr = i + 1
		
		i, j = dateStr:find("-", ptr)
		
		if i then
			-- month
			parts[index] = tonumber(dateStr:sub(ptr, i-1), 10)
			
			if precision == "m" then
				-- we're done
				return parts[1], parts[2], parts[3]  -- year, month, day
			end
			
			index = index + 1
			ptr = i + 1
		end
	end
	
	if dateStr:sub(ptr) ~= "" then
		-- day if we have month, month if we have year, or year
		parts[index] = tonumber(dateStr:sub(ptr), 10)
	end
	
	return parts[1], parts[2], parts[3]  -- year, month, day
end

function convertUnit(unit, link)
	link = link or false
	local itemID, label, title
	
	if unit == "" or unit == "1" then
		return nil
	end
	
	itemID = parseWikidataURL(unit)
	
	if itemID then
		if itemID == aliasesQ.percentage then
			return "%"
		else
			label = mw.wikibase.label(itemID)
			title = nil
			
			if link or label == nil then
				title = mw.wikibase.sitelink(itemID)
			end
			
			if link then
				if title then
					return " " .. "[[" .. title .. "|" .. (label or title) .. "]]"
				end
				
				if not label then
					return " " .. "[[d:" .. itemID .. "|" .. itemID .. "]]"
				end
			end
			
			return " " .. (label or title or itemID)
		end
	end
	
	return " " .. unit
end

function getOrdinalSuffix(num)
	if tostring(num):sub(-2,-2) == '1' then
		return "th"  -- 10th, 11th, 12th, 13th, ... 19th
	end
	
	num = tostring(num):sub(-1)
	
	if num == '1' then
		return "st"
	elseif num == '2' then
		return "nd"
	elseif num == '3' then
		return "rd"
	else
		return "th"
	end
end

function addDecimalMarks(n)
	local left,num,right = string.match(n,'^([^%d]*%d)(%d*)(.-)$')
	return left..(num:reverse():gsub('(%d%d%d)','%1,'):reverse())..right
end

function convertRank(rank)
	if rank == "preferred" then
		return 1
	elseif rank == "normal" then
		return 2
	elseif rank == "deprecated" then
		return 3
	else
		return 4  -- default (in its literal sense)
	end
end

function datePrecedesDate(aY, aM, aD, bY, bM, bD)
	if aY == nil or bY == nil then
		return nil
	end
	aM = aM or 1
	aD = aD or 1
	bM = bM or 1
	bD = bD or 1
	
	if aY < bY then
		return true
	end
	
	if aY > bY then
		return false
	end
	
	if aM < bM then
		return true
	end
	
	if aM > bM then
		return false
	end
	
	if aD < bD then
		return true
	end
	
	return false
end

function alwaysTrue()
	return true
end

function parseFormat(str)
	local chr, esc, param, root, cur
	local params = {}
	
	local function newObject(array)
		local obj = {}  -- new object
		obj.str = ""
		
		array[#array + 1] = obj  -- array{object}
		obj.parent = array
		
		return obj
	end
	
	root = {}  -- array
	root.req = {}
	cur = newObject(root)
	
	esc = false
	param = false
	
	for i = 1, #str do
		chr = str:sub(i,i)
		
		if not esc then
			if chr == '\\' then
				esc = true
			elseif chr == '%' then
				cur = newObject(cur.parent)
				param = true
			else
				if chr == '[' then
					cur.child = {}  -- new array
					cur.child.req = {}
					cur.child.parent = cur
					cur = newObject(cur.child)
				elseif chr == ']' then
					if cur.parent.parent then
						cur = newObject(cur.parent.parent.parent)
					end
				else
					cur.str = cur.str .. chr
					
					if param then
						cur.str = "%"..cur.str
						cur.param = true
						params[cur.str] = true
						cur.parent.req[cur.str] = true
						cur = newObject(cur.parent)
					end
				end
				
				param = false
			end
		else
			cur.str = cur.str .. chr
			esc = false
			
			if param then
				cur.str = "%"..cur.str
				cur.param = true
				params[cur.str] = true
				cur.parent.req[cur.str] = true
				cur = newObject(cur.parent)
				param = false
			end
		end
	end
	
	return root, params
end

function getShortName(itemID)
	return p._property({itemID, aliasesP.shortName})  -- "property" is single
end

function getLabel(ID)
	return p._label({ID})
end

function Config:getValue(snak, raw, link, short, anyLang)
	raw = raw or false
	link = link or false
	short = short or false
	anyLang = anyLang or false
	
	if snak.snaktype == 'value' then
		if snak.datavalue.type == 'string' then
			return snak.datavalue.value
		elseif snak.datavalue.type == 'monolingualtext' then
			if anyLang then
				return snak.datavalue.value['text'], snak.datavalue.value['language']
			elseif snak.datavalue.value['language'] == self.langCode then
				return snak.datavalue.value['text']
			else
				return nil
			end
		elseif snak.datavalue.type == 'quantity' then
			-- strip + signs from front
			local value = mw.ustring.gsub(snak.datavalue.value['amount'], "^\+(.+)$", "%1")
			
			if not raw then
				value = addDecimalMarks(value)
				local unit = convertUnit(snak.datavalue.value['unit'], link)
				if unit then
					value = value .. unit
				end
			end
			
			return value
		elseif snak.datavalue.type == 'time' then
			local y, m, d, p, yDiv, yRound, yFull, value, calendarID, dateStr
			local yFactor = 1
			local sign = 1
			local suffix = ""
			local mayAddCalendar = false
			local calendar = ""
			local precision = snak.datavalue.value['precision']
			
			if precision == 11 then
				p = "d"
			elseif precision == 10 then
				p = "m"
			else
				p = "y"
				yFactor = 10^(9-precision)
			end
			
			y, m, d = parseDate(snak.datavalue.value['time'], p)
			
			if y < 0 then
				sign = -1
				y = y * sign
			end
			
			-- if precision is tens/hundreds/thousands/millions/billions of years
			if precision <= 8 then
				yDiv = y / yFactor
				
				-- if precision is tens/hundreds/thousands of years
				if precision >= 6 then
					mayAddCalendar = true
					
					if precision <= 7 then
						-- round centuries/millenniums up (e.g. 20th century or 3rd millennium)
						yRound = math.ceil(yDiv)
						
						if not raw then
							if precision == 6 then
								suffix = " millennium"
							else
								suffix = " century"
							end
							
							suffix = getOrdinalSuffix(yRound) .. suffix
						else
							-- if not verbose, take the first year of the century/millennium
							-- (e.g. 1901 for 20th century or 2001 for 3rd millennium)
							yRound = (yRound - 1) * yFactor + 1
						end
					else
						-- precision == 8
						-- round decades down (e.g. 2010s)
						yRound = math.floor(yDiv) * yFactor
						
						if not raw then
							suffix = "s"
						end
					end
					
					if raw and sign < 0 then
						-- if BCE then compensate for "counting backwards"
						-- (e.g. -2019 for 2010s BCE, -2000 for 20th century BCE or -3000 for 3rd millennium BCE)
						yRound = yRound + yFactor - 1
					end
				else
					local yReFactor, yReDiv, yReRound
					
					-- round to nearest for tens of thousands of years or more
					yRound = math.floor(yDiv + 0.5)
					
					if yRound == 0 then
						if precision <= 2 and y ~= 0 then
							yReFactor = 1e6
							yReDiv = y / yReFactor
							yReRound = math.floor(yReDiv + 0.5)
							
							if yReDiv == yReRound then
								-- change precision to millions of years only if we have a whole number of them
								precision = 3
								yFactor = yReFactor
								yRound = yReRound
							end
						end
						
						if yRound == 0 then
							-- otherwise, take the unrounded (original) number of years
							precision = 5
							yFactor = 1
							yRound = y
							mayAddCalendar = true
						end
					end
					
					if precision >= 1 and y ~= 0 then
						yFull = yRound * yFactor
						
						yReFactor = 1e9
						yReDiv = yFull / yReFactor
						yReRound = math.floor(yReDiv + 0.5)
						
						if yReDiv == yReRound then
							-- change precision to billions of years if we're in that range
							precision = 0
							yFactor = yReFactor
							yRound = yReRound
						else
							yReFactor = 1e6
							yReDiv = yFull / yReFactor
							yReRound = math.floor(yReDiv + 0.5)
							
							if yReDiv == yReRound then
								-- change precision to millions of years if we're in that range
								precision = 3
								yFactor = yReFactor
								yRound = yReRound
							end
						end
					end
					
					if not raw then
						if precision == 3 then
							suffix = " million years"
						elseif precision == 0 then
							suffix = " billion years"
						else
							yRound = yRound * yFactor
							if yRound == 1 then
								suffix = " year"
							else
								suffix = " years"
							end
						end
					else
						yRound = yRound * yFactor
					end
				end
			else
				yRound = y
				mayAddCalendar = true
			end
			
			if mayAddCalendar then
				calendarID = parseWikidataURL(snak.datavalue.value['calendarmodel'])
				
				if calendarID and calendarID == aliasesQ.prolepticJulianCalendar then
					if not raw then
						if link then
							calendar = " ([[Julian calendar|Julian]])"
						else
							calendar = " (Julian)"
						end
					else
						calendar = "/Julian"
					end
				end
			end
			
			if not raw then
				local ce = nil
				
				if sign < 0 then
					ce = "BCE"
				elseif precision <= 5 then
					ce = "CE"
				end
				
				if ce then
					if link then
						ce = "[[Common Era|" .. ce .. "]]"
					end
					suffix = suffix .. " " .. ce
				end
				
				value = tostring(yRound)
				
				if m then
					dateStr = self.langObj:formatDate("F", "1-"..m.."-1")
					
					if d then
						if self.mdyDate then
							dateStr = dateStr .. " " .. d .. ","
						else
							dateStr = d .. " " .. dateStr
						end
					end
					
					value = dateStr .. " " .. value
				end
				
				value = value .. suffix .. calendar
			else
				value = tostring(yRound * sign)
				
				if m then
					value = value .. "-" .. m
					
					if d then
						value = value .. "-" .. d
					end
				end
				
				value = value .. calendar
			end
			
			return value
		elseif snak.datavalue.type == 'globecoordinate' then
			-- logic from https://github.com/DataValues/Geo
			
			local precision, numDigits, strFormat, value, globe
			local latValue, latitude, latDegrees, latMinutes, latSeconds
			local latDirection = "N"
			local lonValue, longitude, lonDegrees, lonMinutes, lonSeconds
			local lonDirection = "E"
			
			local degSymbol = "°"
			local minSymbol = "'"
			local secSymbol = '"'
			local partsGlue = ", "
			
			if raw then
				degSymbol = "/"
				minSymbol = "/"
				secSymbol = "/"
				partsGlue = "/"
			end
			
			latitude = snak.datavalue.value['latitude']
			longitude = snak.datavalue.value['longitude']
			
			if latitude < 0 then
				latDirection = "S"
				latitude = math.abs(latitude)
			end
			if longitude < 0 then
				lonDirection = "W"
				longitude = math.abs(longitude)
			end
			
			precision = snak.datavalue.value['precision']
			
			latitude = math.floor(latitude / precision + 0.5) * precision
			longitude = math.floor(longitude / precision + 0.5) * precision
			
			numDigits = math.ceil(-math.log10(3600 * precision))
			
			if numDigits < 0 or numDigits == -0 then
				numDigits = 0
			end
			
			strFormat = "%." .. numDigits .. "f"
			
			-- use string.format() to strip decimal point followed by a zero (.0) for whole numbers
			latSeconds = tonumber(string.format(strFormat, math.floor(latitude * 3600 * 10^numDigits + 0.5) / 10^numDigits))
			lonSeconds = tonumber(string.format(strFormat, math.floor(longitude * 3600 * 10^numDigits + 0.5) / 10^numDigits))
			
			latMinutes = math.floor(latSeconds / 60)
			lonMinutes = math.floor(lonSeconds / 60)
			
			latSeconds = latSeconds - (latMinutes * 60)
			lonSeconds = lonSeconds - (lonMinutes * 60)
			
			latDegrees = math.floor(latMinutes / 60)
			lonDegrees = math.floor(lonMinutes / 60)
			
			latMinutes = latMinutes - (latDegrees * 60)
			lonMinutes = lonMinutes - (lonDegrees * 60)
			
			latValue = latDegrees .. degSymbol
			lonValue = lonDegrees .. degSymbol
			
			if precision < 1 then
				latValue = latValue .. latMinutes .. minSymbol
				lonValue = lonValue .. lonMinutes .. minSymbol
			end
			
			if precision < (1 / 60) then
				latSeconds = string.format(strFormat, latSeconds)
				lonSeconds = string.format(strFormat, lonSeconds)
				
				latValue = latValue .. latSeconds .. secSymbol
				lonValue = lonValue .. lonSeconds .. secSymbol
			end
			
			latValue = latValue .. latDirection
			lonValue = lonValue .. lonDirection
			
			value = latValue .. partsGlue .. lonValue
			
			if link then
				globe = parseWikidataURL(snak.datavalue.value['globe'])
				
				if globe then
					globe = mw.wikibase.label(globe):lower()
				else
					globe = "earth"
				end
				
				value = "[https://tools.wmflabs.org/geohack/geohack.php?language="..self.langCode.."&params="..latitude.."_"..latDirection.."_"..longitude.."_"..lonDirection.."_globe:"..globe.." "..value.."]"
			end
			
			return value
		elseif snak.datavalue.type == 'wikibase-entityid' then
			local value = ""
			local title = nil
			local itemID = "Q" .. snak.datavalue.value['numeric-id']
			
			if raw then
				if link then
					return "[[d:" .. itemID .. "|" .. itemID .. "]]"
				else
					return itemID
				end
			end
			
			if short then
				value = getShortName(itemID)
			end
			
			if value == "" then
				value = mw.wikibase.label(itemID)
			end
			
			if link or value == nil then
				title = mw.wikibase.sitelink(itemID)
			end
			
			if link then
				if title then
					value = "[[" .. title .. "|" .. (value or title) .. "]]"
				elseif not value then
					value = "[[d:" .. itemID .. "|" .. itemID .. "]]"
				end
			elseif not value then
				value = (title or itemID)
			end
			
			return value
		else
			return '<strong class="error">' .. unknownDataTypeError(snak.datavalue.type) .. '.</strong>'
		end
	elseif snak.snaktype == 'somevalue' then
		if raw then
			return " "  -- single space represents 'somevalue'
		else
			return "unknown"
		end
	elseif snak.snaktype == 'novalue' then
		if raw then
			return ""  -- empty string represents 'novalue'
		else
			return "none"
		end
	else
		return nil
	end
end

function Config:getSingleRawQualifier(claim, qualifierID)
	local qualifiers
	
	if claim.qualifiers then qualifiers = claim.qualifiers[qualifierID] end
	
	if qualifiers and qualifiers[1] then
		return self:getValue(qualifiers[1], true)  -- raw = true
	else
		return nil
	end
end

function Config:snakEqualsValue(snak, value)
	local snakValue = self:getValue(snak, true)  -- raw = true
	
	if snakValue and snak.snaktype == 'value' and snak.datavalue.type == 'wikibase-entityid' then value = value:upper() end
	
	return snakValue == value
end

function Config:setRank(rank)
	local rankPos
	
	if rank == "best" then
		self.bestRank = true
		self.flagBest = true  -- mark that 'best' flag was given
		return
	end
	
	if rank:sub(1,9) == "preferred" then
		rankPos = 1
	elseif rank:sub(1,6) == "normal" then
		rankPos = 2
	elseif rank:sub(1,10) == "deprecated" then
		rankPos = 3
	else
		return
	end
	
	-- one of the rank flags was given, check if another one was given before
	if not self.flagRank then
		self.ranks = {false, false, false}  -- no other rank flag given before, so unset ranks
		self.bestRank = self.flagBest       -- unsets bestRank only if 'best' flag was not given before
		self.flagRank = true                -- mark that a rank flag was given
	end
	
	if rank:sub(-1) == "+" then
		for i = rankPos, 1, -1 do
			self.ranks[i] = true
		end
	elseif rank:sub(-1) == "-" then
		for i = rankPos, #self.ranks do
			self.ranks[i] = true
		end
	else
		self.ranks[rankPos] = true
	end
end

function Config:setPeriod(period)
	local periodPos
	
	if period == "future" then
		periodPos = 1
	elseif period == "current" then
		periodPos = 2
	elseif period == "former" then
		periodPos = 3
	else
		return
	end
	
	-- one of the period flags was given, check if another one was given before
	if not self.flagPeriod then
		self.periods = {false, false, false}  -- no other period flag given before, so unset periods
		self.flagPeriod = true                -- mark that a period flag was given
	end
	
	self.periods[periodPos] = true
end

function Config:processFlag(flag)
	if not flag then
		return false
	else
		flag = mw.text.trim(flag)
	end
	
	if flag == "linked" then
		self.curState.linked = true
		return true
	elseif flag == "raw" then
		self.curState.rawValue = true
		
		if self.curState == self.states[parameters.reference] then
			-- raw reference values end with periods and require a separator different from ""
			self.separators["sep%r"][1] = " "
		end
		
		return true
	elseif flag == "short" then
		self.curState.shortName = true
		return true
	elseif flag == "mdy" then
		self.mdyDate = true
		return true
	elseif flag == "best" or flag:match('^preferred[+-]?$') or flag:match('^normal[+-]?$') or flag:match('^deprecated[+-]?$') then
		self:setRank(flag)
		return true
	elseif flag == "future" or flag == "current" or flag == "former" then
		self:setPeriod(flag)
		return true
	elseif flag == "" then
		-- ignore empty flags and carry on
		return true
	else
		return false
	end
end

function Config:processFlagOrCommand(flag)
	local param = ""
	
	if not flag then
		return false
	else
		flag = mw.text.trim(flag)
	end
	
	if flag == "property" or flag == "properties" then
		param = parameters.property
	elseif flag:match('^qualifier[s]?$') then
		param = parameters.qualifier
	elseif flag:match('^reference[s]?$') then
		param = parameters.reference
	else
		return self:processFlag(flag)
	end
	
	if self.states[param] then
		return false
	end
	
	-- create a new State for each command
	self.states[param] = State.new(self)
	
	-- use "%x" as the general parameter name
	self.states[param].parsedFormat = parseFormat("%x")  -- will be overwritten for param=="%p"
	
	-- set the separator
	self.states[param].separator = self.separators["sep"..param]  -- will be nil for param=="%p", which will be set separately
	
	if string.sub(flag, -1) ~= 's' then
		self.states[param].singleValue = true
	end
	
	self.curState = self.states[param]
	
	return true
end

function Config:rankMatches(rankPos)
	if self.bestRank then
		return (self.ranks[rankPos] and self.foundRank >= rankPos)
	else
		return self.ranks[rankPos]
	end
end

function Config:timeMatches(claim)
	local startTime = nil
	local startTimeY = nil
	local startTimeM = nil
	local startTimeD = nil
	local endTime = nil
	local endTimeY = nil
	local endTimeM = nil
	local endTimeD = nil
	
	if self.periods[1] and self.periods[2] and self.periods[3] then
		-- any time
		return true
	end
	
	local now = os.date('!*t')
	
	startTime = self:getSingleRawQualifier(claim, aliasesP.startTime)
	if startTime and startTime ~= "" and startTime ~= " " then
		startTimeY, startTimeM, startTimeD = parseDate(startTime)
	end
	
	endTime = self:getSingleRawQualifier(claim, aliasesP.endTime)
	if endTime and endTime ~= "" and endTime ~= " " then
		endTimeY, endTimeM, endTimeD = parseDate(endTime)
	elseif endTime == " " then
		-- end time is 'unknown', assume it is somewhere in the past;
		-- we can do this by taking the current date as a placeholder for the end time
		endTimeY = now['year']
		endTimeM = now['month']
		endTimeD = now['day']
	end
	
	if startTimeY ~= nil and endTimeY ~= nil and datePrecedesDate(endTimeY, endTimeM, endTimeD, startTimeY, startTimeM, startTimeD) then
		-- invalidate end time if it precedes start time
		endTimeY = nil
		endTimeM = nil
		endTimeD = nil
	end
	
	if self.periods[1] then
		-- future
		if startTimeY and datePrecedesDate(now['year'], now['month'], now['day'], startTimeY, startTimeM, startTimeD) then
			return true
		end
	end
	
	if self.periods[2] then
		-- current
		if (startTimeY == nil or not datePrecedesDate(now['year'], now['month'], now['day'], startTimeY, startTimeM, startTimeD)) and
		   (endTimeY == nil or datePrecedesDate(now['year'], now['month'], now['day'], endTimeY, endTimeM, endTimeD)) then
		   	return true
		end
	end
	
	if self.periods[3] then
		-- former
		if endTimeY and not datePrecedesDate(now['year'], now['month'], now['day'], endTimeY, endTimeM, endTimeD) then
			return true
		end
	end
	
	return false
end

function State:claimMatches(claim)
	local matches, rankPos
	
	-- if a property value was given, check if it matches the claim's property value
	if self.conf.propertyValue then
		matches = self.conf:snakEqualsValue(claim.mainsnak, self.conf.propertyValue)
	else
		matches = true
	end
	
	-- check if the claim's rank and time period match
	rankPos = convertRank(claim.rank)
	matches = (matches and self.conf:rankMatches(rankPos) and self.conf:timeMatches(claim))
	
	return matches, rankPos
end

function State:appendOutput(result, rankPos)
	local done = false
	
	-- a rankPos should only apply to complete claims, NOT to its individual qualifiers or references;
	-- for the latter two, no rankPos should be given and their default rankPos must be the highest possible (i.e. 1)
	if rankPos then
		-- must NOT be reached when appending individual qualifiers or references
		if self.conf.foundRank > rankPos then
			self.conf.foundRank = rankPos  -- must NOT be overwritten when appending individual qualifiers or references
			
			if self.conf.bestRank or self.singleValue then
				-- found a better rank, reset worse rank outputs
				if self.conf.foundRank == 1 then
					self.outNormal = {}
					self.outDeprecated = {}
				elseif self.conf.foundRank == 2 then
					self.outDeprecated = {}
				end
			end
		end
	else
		-- must be reached when appending individual qualifiers or references
		rankPos = 1  -- must be the highest possible (i.e. 1)
	end
	
	if rankPos == 1 then
		-- must always be reached when appending individual qualifiers or references
		self.outPreferred[#self.outPreferred + 1] = result
		
		if self.singleValue then
			done = true
		end
	elseif rankPos == 2 then
		self.outNormal[#self.outNormal + 1] = result
		
		if self.singleValue and not self.conf.ranks[1] then
			done = true
		end
	elseif rankPos == 3 then
		self.outDeprecated[#self.outDeprecated + 1] = result
		
		if self.singleValue and not self.conf.ranks[1] and not self.conf.ranks[2] then
			done = true
		end
	end
	
	return done
end

function State:out()
	local out = ""
	
	local function walk(formatTable, result)
		local str = ""
		
		for i, v in pairs(formatTable.req) do
			if not result[i] then
				-- we've got no result for a parameter that is required on this level,
				-- so skip this level (and its children) by returning an empty string
				return ""
			end
		end
		
		for i, v in ipairs(formatTable) do
			if v.param then
				str = str .. result[v.str]
			else
				str = str .. v.str
			end
			
			if v.child then
				str = str .. walk(v.child, result)
			end
		end
		
		return str
	end
	
	local function prepend(results)
		local sep = ""
		local result, value
		
		-- iterate from back to front, so that we know when to add separators
		for i = #results, 1, -1 do
			result = results[i]
			
			-- if there is already some output, then add the separators
			if out ~= "" then
				sep = self.separator[1]  -- fixed separator
				result[parameters.separator] = self.movSeparator[1]  -- movable separator
			else
				sep = ""
				result[parameters.separator] = self.puncMark[1]  -- optional punctuation mark
			end
			
			value = walk(self.parsedFormat, result)
			
			if value ~= "" then
				out = value .. sep .. out
			end
		end
	end
	
	prepend(self.outDeprecated)
	prepend(self.outNormal)
	prepend(self.outPreferred)
	
	-- reset state before next iteration
	self.outDeprecated = {}
	self.outNormal = {}
	self.outPreferred = {}
	
	return out
end

-- level 1 hook
function State:getProperty(claim)
	return self.conf:getValue(claim.mainsnak, self.rawValue, self.linked, self.shortName)
end

-- level 1 hook
function State:getQualifiers(claim)
	local qualifiers
	
	if claim.qualifiers then qualifiers = claim.qualifiers[self.conf.qualifierID] end
	if qualifiers then
		-- iterate through claim's qualifier statements to collect their values
		return self.conf.states[parameters.qualifier]:iterate(qualifiers, {["%x"] = hookNames[parameters.qualifier][2], count = 1})  -- pass qualifier State with level 2 hook
	else
		return nil
	end
end

-- level 2 hook
function State:getQualifier(snak)
	return self.conf:getValue(snak, self.rawValue, self.linked, self.shortName)
end

-- level 1 hook
function State:getReferences(claim)
	if claim.references then
		-- iterate through claim's reference statements to collect their values
		return self.conf.states[parameters.reference]:iterate(claim.references, {["%x"] = hookNames[parameters.reference][2], count = 1})  -- pass reference State with level 2 hook
	else
		return nil
	end
end

-- level 2 hook
-- logic determined based on https://www.wikidata.org/wiki/Help:Sources
function State:getReference(statement)
	local snakValue, lang, property
	local value = ""
	local snaks = {}
	local params = {}
	local leadParams = {}
	
	if statement.snaks then
		for i, v in pairs(statement.snaks) do
			if v[1] then
				snaks[i] = v[1]
			end
		end
		
		if snaks[aliasesP.importedFrom] then
			snaks[aliasesP.importedFrom] = nil
		end
		
		if snaks[aliasesP.referenceURL] and snaks[aliasesP.title] then
			params["url"] = self.conf:getValue(snaks[aliasesP.referenceURL])
			params["title"] = self.conf:getValue(snaks[aliasesP.title], false, false, false, true)  -- anyLang = true
			
			if snaks[aliasesP.publicationDate] then params["date"]         = self.conf:getValue(snaks[aliasesP.publicationDate])                  end
			if snaks[aliasesP.retrieved]       then params["access-date"]  = self.conf:getValue(snaks[aliasesP.retrieved])                        end
			if snaks[aliasesP.archiveURL]      then params["archive-url"]  = self.conf:getValue(snaks[aliasesP.archiveURL])                       end
			if snaks[aliasesP.archiveDate]     then params["archive-date"] = self.conf:getValue(snaks[aliasesP.archiveDate])                      end
			if snaks[aliasesP.author]          then params["author"]       = self.conf:getValue(snaks[aliasesP.author])                           end
			if snaks[aliasesP.publisher]       then params["publisher"]    = self.conf:getValue(snaks[aliasesP.publisher])                        end
			if snaks[aliasesP.quote]           then params["quote"]        = self.conf:getValue(snaks[aliasesP.quote], false, false, false, true) end  -- anyLang = true
			
			if snaks[aliasesP.language] then
				snakValue = self.conf:getValue(snaks[aliasesP.language])
				
				if self.conf.langName ~= snakValue then
					params["language"] = snakValue
				end
			end
			
			value = mw.getCurrentFrame():expandTemplate{title="cite_web", args=params}
		else
			for i, v in pairs(snaks) do
				property = getLabel(i)
				
				if property ~= "" then
					snakValue, lang = self.conf:getValue(v, false, (i == aliasesP.statedIn), false, true)  -- link = true/false, anyLang = true
					
					if lang and lang ~= self.conf.langCode then
						snakValue = "''" .. snakValue .. "'' (" .. mw.language.fetchLanguageName(lang, self.conf.langCode) .. ")"
					end
					
					if i == aliasesP.referenceURL or i == aliasesP.statedIn then
						leadParams[#leadParams + 1] = snakValue
					elseif i ~= aliasesP.language or self.conf.langName ~= snakValue then
						params[#params + 1] = property .. ": " .. snakValue
					end
				end
			end
			
			value = table.concat(leadParams, "; ")
			params = table.concat(params, "; ")
			
			if params ~= "" then
				if value ~= "" then
					value = value .. "; "
				end
				value = value .. params
			end
			
			if value ~= "" then
				value = value .. "."
			end
		end
		
		if value ~= "" then
			if not self.rawValue then
				-- add <ref> tags with the reference's hash as its name (to deduplicate references)
				value = mw.getCurrentFrame():extensionTag("ref", value, {name = "wikidata-" .. statement.hash})
			end
		else
			value = nil
		end
	end
	
	return value
end

-- iterate through claims, claim's qualifiers or claim's references to collect values
function State:iterate(statements, hooks, matchHook)
	matchHook = matchHook or alwaysTrue
	
	local done = false
	local matches = false
	local rankPos = nil
	local result, numValues, doAppend, gotRequired
	
	for i, v in ipairs(statements) do
		-- rankPos will be nil for non-claim statements (e.g. qualifiers, references, etc.),
		-- but let appendOutput handle that
		matches, rankPos = matchHook(self, v)
		
		if matches then
			result = {count = 0}
			doAppend = true
			
			-- if we need to return a single value, check if we don't have one already
			if self.singleValue then
				if not rankPos or rankPos == 1 then
					numValues = #self.outPreferred
				elseif rankPos == 2 then
					numValues = #self.outNormal
				elseif rankPos == 3 then
					numValues = #self.outDeprecated
				end
				
				if numValues > 0 then
					doAppend = false
				end
			end
			
			if doAppend then
				local function walk(formatTable)
					local value
					
					for i2, v2 in pairs(formatTable.req) do
						if not result[i2] and hooks[i2] then
							-- call a hook and add its return value to the result
							value = self[hooks[i2]](self, v)
							
							if value then
								result[i2] = value
								result.count = result.count + 1
							else
								return false  -- we miss a required value for this level
							end
						end
						
						if result.count == hooks.count then
							-- we're done if all hooks have been called;
							-- returning at this point breaks the loop
							return true
						end
					end
					
					for i2, v2 in ipairs(formatTable) do
						if result.count == hooks.count then
							-- we're done if all hooks have been called;
							-- returning at this point prevents further childs from being processed
							return true
						end
						
						if v2.child then
							walk(v2.child)
						end
					end
					
					return true
				end
				gotRequired = walk(self.parsedFormat)
				
				-- only append the result if we got values for all required parameters on the root level
				if gotRequired then
					done = self:appendOutput(result, rankPos)
					if done then
						break
					end
				end
			end
		end
	end
	
	return self:out()
end

function p.property(frame)
	return p._property(frame.args)
end

function p._property(args)
	return execCommand(args, "property")
end

function p.properties(frame)
	return p._properties(frame.args)
end

function p._properties(args)
	return execCommand(args, "properties")
end

function p.qualifier(frame)
	return p._qualifier(frame.args)
end

function p._qualifier(args)
	return execCommand(args, "qualifier")
end

function p.qualifiers(frame)
	return p._qualifiers(frame.args)
end

function p._qualifiers(args)
	return execCommand(args, "qualifiers")
end

function p.reference(frame)
	return p._reference(frame.args)
end

function p._reference(args)
	return execCommand(args, "reference")
end

function p.references(frame)
	return p._references(frame.args)
end

function p._references(args)
	return execCommand(args, "references")
end

function execCommand(args, funcName)
	_ = Config.new()
	_:processFlagOrCommand(funcName)  -- process first command (== function name)
	
	local parsedFormat, formatParams, claims
	local hooks = {count = 0}
	
	local nextArg = args[1]
	local nextIndex = 2
	
	-- process flags and commands
	while _:processFlagOrCommand(nextArg) do
		nextArg = args[nextIndex]
		nextIndex = nextIndex + 1
	end
	
	if nextArg then
		nextArg = mw.text.trim(nextArg)
	else
		nextArg = ""
	end
	
	-- check for optional item ID
	if nextArg:sub(1,1):upper() == "Q" then
		_.entity = mw.wikibase.getEntity(nextArg)  -- item ID given
		_.propertyID = mw.text.trim(args[nextIndex] or "")  -- property ID
		nextIndex = nextIndex + 1
	else
		_.entity = mw.wikibase.getEntity()  -- no item ID given, use item connected to current page
		_.propertyID = nextArg  -- property ID
	end
	
	-- check if given property ID is an alias
	if aliasesP[_.propertyID] then
		_.propertyID = aliasesP[_.propertyID]
	end
	
	_.propertyID = _.propertyID:upper()
	
	if _.states[parameters.qualifier] then
		-- do further processing if "qualifier(s)" command was given
		
		nextArg = args[nextIndex]
		nextIndex = nextIndex + 1
		
		_.qualifierID = nextArg  -- is possibly actually propertyValue, so don't trim just yet
		
		nextArg = mw.text.trim(args[nextIndex] or "")
		nextIndex = nextIndex + 1
		
		if nextArg == "" then
			-- claim ID or literal value has NOT been given
			_.propertyValue = nil
			_.qualifierID = mw.text.trim(_.qualifierID or "")
		else
			-- claim ID or literal value has been given
			_.propertyValue = _.qualifierID  -- cannot be nil when reached
			_.qualifierID = nextArg
		end
		
		-- check if given qualifier ID is an alias
		if aliasesP[_.qualifierID] then
			_.qualifierID = aliasesP[_.qualifierID]
		end
		
		_.qualifierID = _.qualifierID:upper()
	elseif _.states[parameters.reference] then
		-- do further processing if "reference(s)" command was given
		
		nextArg = args[nextIndex]
		nextIndex = nextIndex + 1
		
		_.propertyValue = nextArg  -- claim ID or literal value (possibly nil)
	end
	
	-- check for special property value 'somevalue' or 'novalue'
	if _.propertyValue then
		if _.propertyValue ~= "" and mw.text.trim(_.propertyValue) == "" then
			_.propertyValue = " "  -- single space represents 'somevalue', whereas empty string represents 'novalue'
		else
			_.propertyValue = mw.text.trim(_.propertyValue)
		end
	end
	
	-- parse the desired format, or choose an appropriate format
	if args["format"] then
		parsedFormat, formatParams = parseFormat(mw.text.trim(args["format"]))
	elseif _.states[parameters.qualifier] then
		if _.states[parameters.property] then
			parsedFormat, formatParams = parseFormat(formats.propertyWithQualifier)
		else
			parsedFormat, formatParams = parseFormat(formats.qualifier)
		end
	elseif _.states[parameters.property] then
		parsedFormat, formatParams = parseFormat(formats.property)
	else
		parsedFormat, formatParams = parseFormat(formats.reference)
		
		-- if only "reference(s)" has been given, make the emtpy string the default separator (except when raw)
		if not _.states[parameters.reference].rawValue then
			_.separators["sep"][1] = ""
		end
	end
	
	-- process overridden separator values;
	-- must come AFTER parsing the formats
	for i, v in pairs(_.separators) do
		if args[i] then
			_.separators[i][1] = args[i]
		end
	end
	
	-- make sure that at least one required parameter has been defined
	if not next(parsedFormat.req) then
		error(missingRequiredParameterError())
	end
	
	-- make sure that the separator parameter "%s" is not amongst the required parameters
	if parsedFormat.req[parameters.separator] then
		error(extraRequiredParameterError(parameters.separator))
	end
	
	-- define the hooks that should be called (getProperty, getQualifiers, getReferences);
	-- only define a hook if both its command ("propert(y|ies)", "qualifier(s)", "reference(s)") and its parameter ("%p", "%q", "%r") have been given
	for i, v in pairs(_.states) do
		if formatParams[i] then
			hooks[i] = hookNames[i][1]
			hooks.count = hooks.count + 1
		end
	end
	
	-- create a state for "properties" if it doesn't exist yet, which will be used as a base configuration for each claim iteration;
	-- must come AFTER defining the hooks
	if not _.states[parameters.property] then
		_.states[parameters.property] = State.new(_)
	end
	
	-- set the parsed format and the separators (and optional punctuation mark)
	_.states[parameters.property].parsedFormat = parsedFormat
	_.states[parameters.property].separator = _.separators["sep"]
	_.states[parameters.property].movSeparator = _.separators["sep"..parameters.separator]
	_.states[parameters.property].puncMark = _.separators["punc"]
	
	if _.entity and _.entity.claims then claims = _.entity.claims[_.propertyID] end
	if claims then
		-- iterate through the claims to collect values
		return _.states[parameters.property]:iterate(claims, hooks, State.claimMatches)  -- pass property State with level 1 hooks and matchHook
	else
		return ""
	end
end

function p.label(frame)
	return p._label(frame.args)
end

function p._label(args, _)
	_ = _ or Config.new()
	_.curState = State.new(_)
	
	local ID
	local label = ""
	local title = nil
	
	local nextArg = args[1]
	local nextIndex = 2
	
	while _:processFlag(nextArg) do
		nextArg = args[nextIndex]
		nextIndex = nextIndex + 1
	end
	
	if nextArg then
		nextArg = mw.text.trim(nextArg)
	else
		nextArg = ""
	end
	
	ID = nextArg
	
	if ID ~= "" then
		if aliasesP[ID] then
			ID = aliasesP[ID]
		end
		
		ID = ID:upper()
		
		-- check if this is a valid ID, and if the number is not larger than max int (to prevent error)
		if not string.match(ID, '^[QP]%d+$') or tonumber(string.match(ID, '%d+')) > 2147483647 then
			return ""
		end
		
		if _.curState.rawValue then
			if mw.wikibase.getEntity(ID) or mw.wikibase.resolvePropertyId(ID) then
				if _.curState.linked then
					if ID:sub(1,1) == "P" then
						label = "[[d:Property:" .. ID .. "|" .. ID .. "]]"
					else
						label = "[[d:" .. ID .. "|" .. ID .. "]]"
					end
				else
					label = ID
				end
			end
		else
			if ID:sub(1,1) == "P" then
				if not _.pageTitle then
					label = mw.wikibase.label(ID) or ""
					
					if _.curState.linked and label ~= "" then
						label = "[[d:Property:" .. ID .. "|" .. label .. "]]"
					end
				end
			else
				if not _.pageTitle then
					if _.curState.shortName then
						label = getShortName(ID)
					end
					
					-- at this point, 'label' will be a string and not nil
					
					if label == "" then
						label = mw.wikibase.label(ID)
					end
				else
					-- set 'label' to nil so 'title' will always prevail
					label = nil
				end
				
				-- at this point, 'label' will be nil or a non-empty string
				
				if _.curState.linked or label == nil then
					title = mw.wikibase.sitelink(ID)
				end
				
				if _.curState.linked and title then
					label = "[[" .. title .. "|" .. (label or title) .. "]]"
				else
					label = label or title or ""
				end
			end
		end
	else
		if _.curState.rawValue then
			label = mw.wikibase.getEntityIdForCurrentPage() or ""
			
			if _.curState.linked and label ~= "" then
				label = "[[d:" .. label .. "|" .. label .. "]]"
			end
		else
			if not _.pageTitle then
				label = mw.wikibase.label()
			else
				-- set 'label' to nil so 'title' will always prevail
				label = nil
			end
			
			if _.curState.linked or label == nil then
				title = mw.title.getCurrentTitle().prefixedText
			end
			
			if _.curState.linked then
				label = "[[" .. title .. "|" .. (label or title) .. "]]"  -- not much use since it links to the current page, but does add wiki mark-up
			else
				label = label or title
			end
		end
	end
	
	return label
end

function p.title(frame)
	return p._title(frame.args)
end

function p._title(args, _)
	_ = _ or Config.new()
	_.pageTitle = true
	return p._label(args, _)
end

-- main function that is supposed be used by a wrapper template
function p.main(frame)
	local f, args, i, v
	
	-- get the parent frame to take the arguments that were passed to the wrapper template
	frame = frame:getParent() or frame
	
	f = mw.text.trim(frame.args[1] or "")
	
	if f == "main" then
		error('The function "main" cannot be called twice')
	end
	
	assert(p["_"..f], 'The function "' .. f .. '" does not exist')
	
	args = {}
	
	-- copy arguments from immutable to mutable table
	for i, v in pairs(frame.args) do
		args[i] = v
	end
	
	-- remove the function name from the list
	table.remove(args, 1)
	
	return p["_"..f](args)
end

return p