View source for Module:YouTubeSubscribers

POINT_IN_TIME_PID = "P585"
YT_CHAN_ID_PID= "P2397"
SUB_COUNT_PID = "P8687"

local p = {} 

-- taken from https://en.wikipedia.org/wiki/Module:Wd
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 (explicitly give base 10 to prevent error)

		if parts[index] == -0 then
			parts[index] = tonumber("0")  -- for some reason, 'parts[index] = 0' may actually store '-0', so parse from string instead
		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

-- taken from https://en.wikipedia.org/wiki/Module:Wd
local 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
	elseif aY > bY then
		return false
	elseif aM < bM then
		return true
	elseif aM > bM then
		return false
	elseif aD < bD then
		return true
	end

	return false
end

function getClaimDate(claim)
	if claim['qualifiers'] and claim['qualifiers'][POINT_IN_TIME_PID] then 
		local pointsInTime = claim['qualifiers'][POINT_IN_TIME_PID]
		if #pointsInTime ~= 1 then
			-- be conservative in what we accept
			error("Encountered a statement with zero or multiple point in time (P85) qualifiers. Please add or remove point in time information so each statement has exactly one")
		end
		local pointInTime = pointsInTime[1]
		if pointInTime and 
		   pointInTime['datavalue'] and 
		   pointInTime['datavalue']['value'] and 
		   pointInTime['datavalue']['value']['time'] 
		then
			return parseDate(pointInTime['datavalue']['value']['time'])
		end
	end
	return nil
end

-- for a given list of statements find the newest one with a matching qual
function newestMatchingStatement(statements, qual, targetQualValue)
	local newestStatement = nil
	local newestStatementYr = nil
	local newestStatementMo = nil
	local newestStatementDay = nil
    for k, v in pairs(statements) do
    	if v['rank'] ~= "deprecated" and v['qualifiers'] and v['qualifiers'][qual] then
    		local quals = v['qualifiers'][qual]
    		-- should only have one instance of the qualifier on a statement
    		if #quals == 1 then
    			local qual = quals[1]
    			if qual['datavalue'] and qual['datavalue']['value'] then
    				local qualValue = qual['datavalue']['value']
    				if qualValue == targetQualValue then
	    				local targetYr, targetMo, targetDay = getClaimDate(v)
	    				if targetYr then
	    					local older = datePrecedesDate(targetYr, targetMo, targetDay, newestStatementYr, newestStatementMo, newestStatementDay)
	    					if older == nil or not older then
	    						newestStatementYr, newestStatementMo, newestStatementDay = targetYr, targetMo, targetDay
	    						newestStatement = v
	    					end
	    				end
    				end
    			end
    		end
    	end
    end
	return newestStatement
end

-- for a given property and qualifier pair returns the newest statement that matches
function newestMatching(e, prop, qual, targetQualValue)
	-- first check the best statements
	local statements = e:getBestStatements(prop)
	local newestStatement = newestMatchingStatement(statements, qual, targetQualValue)
	if newestStatement then
		return newestStatement
	end
	-- try again with all statements if nothing so far
	statements = e:getAllStatements(prop)
	newestStatement = newestMatchingStatement(statements, qual, targetQualValue)
	if newestStatement then
		return newestStatement
	end
	return nil
end

function getEntity ( frame )
	local qid = nil
	if frame.args then
		qid = frame.args["qid"]
	end
	if not qid then
		qid = mw.wikibase.getEntityIdForCurrentPage()
	end
	if not qid then
		local e = nil
		return e
	end
	local e = mw.wikibase.getEntity(qid)
	assert(e, "No such item found: " .. qid)
	return e
end

-- find the channel ID we are going to be getting the sub counts for
function getBestYtChanId(e) 
	local chanIds = e:getBestStatements(YT_CHAN_ID_PID)
	if #chanIds == 1 then
		local chan = chanIds[1]
		if chan and 
		   chan["mainsnak"] and 
		   chan["mainsnak"]["datavalue"] and 
		   chan["mainsnak"]["datavalue"]["value"] 
		then
			return chan["mainsnak"]["datavalue"]["value"]
		end
	end
	return nil
end

function returnError(frame, eMessage)
	return frame:expandTemplate{ title = 'error', args = { eMessage } } .. "[[Category:Pages with YouTubeSubscribers module errors]]"
end

-- the date of the current YT subscriber count
function p.date( frame )
	local e = getEntity(frame)
	assert(e, "No qid found for page. Please make a Wikidata item for this article")
	local chanId = getBestYtChanId(e)
	assert(chanId, "Could not find a single best YouTube channel ID for this item. Add a YouTube channel ID or set the rank of one channel ID to be preferred")
	local s = newestMatching(e, SUB_COUNT_PID, YT_CHAN_ID_PID, chanId)
	if s then
		local yt_year, yt_month, yt_day = getClaimDate(s)
		if not yt_year then
			return nil
		end
		local dateString = yt_year .. "|"
		-- construct YYYY|mm|dd date string
		if yt_month and yt_month ~= 0 then
			dateString = dateString .. yt_month .. "|"
			-- truncate the day of month
			--if yt_day and yt_day ~= 0 then
			--	dateString = dateString .. yt_day
			--end
		end
		return frame:expandTemplate{title="Format date", args = {yt_year, yt_month, yd_day}}
	end
	error("Could not find a date for YouTube subscriber information. Is there a social media followers statement (P8687) qualified with good values for P585 and P2397?")
end

function p.dateNice( frame )
	local status, obj = pcall(p.date, frame)
	if status then
		return obj
	else 
		return returnError(frame, obj)
	end
end

-- the most up to date number of subscribers
function p.subCount( frame )
	local subCount = nil
	local e = getEntity(frame)
	if not e then
		subCount = -424
    	return tonumber(subCount)
	end
	local chanId = getBestYtChanId(e)
	if chanId then
		local s = newestMatching(e, SUB_COUNT_PID, YT_CHAN_ID_PID, chanId)
		if s and 
		   s["mainsnak"] and 
		   s['mainsnak']["datavalue"] and 
		   s['mainsnak']["datavalue"]["value"] and 
		   s['mainsnak']["datavalue"]['value']['amount']
		then
			subCount = s['mainsnak']["datavalue"]['value']['amount']
		end
	else 
		subCount = -404
	end
    if subCount then
    	return tonumber(subCount)
    else
		subCount = -412
    	return tonumber(subCount)
    end
end

function p.subCountNice( frame )
	local status, obj = pcall(p.subCount, frame)
	if status then
		if obj >= 0 then
			return frame:expandTemplate{title="Format price", args = {obj}}
		else
			return obj
		end
	else 
		return returnError(frame, obj)
	end
end

return p