local p = {};



local function checklayer(depth) -- check subclasses of items at current depth

	checklistdepth+1 = {} -- setup next layer of table

	local j = 0

	for j = 1,#checklistdepth do -- loop over items at current depth

		local property

		if depth == 1 then

			property = "P31" -- use P31 for depth 1

		else

			property = "P279" -- use P279 for depths 2+

		end

		local subclasses = mw.wikibase.getBestStatements(checklistdepth][j],property) -- get P31 or P279 statements

		for i,statement in ipairs(subclasses) do -- loop through items at next depth

			if statement.mainsnak.snaktype == 'value' then

				local newitem = statement.mainsnak.datavalue.value.id

				if newitem == value then

					isInstance = true

				else

					checklistdepth+1][#checklistdepth+1+1 = newitem -- add item to next depth of checklist table

				end

			end

		end

	end

	return isInstance

end



function p.main(frame)

	local args = frame.args

	local pargs = frame:getParent().args

	value = args.value or pargs.value

	local qid = args.qid or pargs.qid or ""

	if qid == "" then

		qid = mw.wikibase.getEntityIdForCurrentPage()

	end

	if not qid then

		return 0

	end

	checklist = {{qid}}

	local md = args.maxdepth or pargs.maxdepth

	if md then

		maxdepth = tonumber(md)

	else

		maxdepth = 5

	end

	depth = 0 -- current depth

	isInstance = false -- assume false until match found

	while not isInstance and depth<maxdepth do

		depth = depth+1

		checklayer(depth)

	end

	if not isInstance then

		depth = 0 -- indicates not isInstance

	end

	return depth -- return depth that item was found

end



return p