Module:Is instance/sandbox

local p = {};

function p._main(args)
	--local pargs = frame:getParent().args
	value = args.value
	local qid = args.qid or ""
	if qid == '' then
		qid = mw.wikibase.getEntityIdForCurrentPage()
	end
	if not qid then
		return 0
	end
	local checklist,depth,maxdepth,isInstance = {{qid}},0,nil,false
	if args.maxdepth then
		maxdepth = tonumber(args.maxdepth)
	else
		maxdepth = 5
	end
	local function checklayer(depth) -- check subclasses of items at current depth
		checklist[depth+1] = {} -- setup next layer of table
		local j = 0
		for j = 1,#checklist[depth] 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(checklist[depth][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
						checklist[depth+1][#checklist[depth+1]+1] = newitem -- add item to next depth of checklist table
					end
				end
			end
		end
		return isInstance
	end
	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

function p.main(frame)
	return p._main(frame.args)	
end

return p