local p = {}

function p.check(frame)
	local taxonbarExists = require('Module:Taxonbar/exists').check
	if taxonbarExists(frame) then
		return ''
	else
		local resolveEntity = require( 'Module:ResolveEntityId' )
		local currentTitle = mw.title.getCurrentTitle()
		local currentItem = nil
		local categories = {
			'[[Category:Taxobox airticles possibly missin a taxonbar]]' --unset if acceptable found
		}
		
		--find Wikidata item
		if currentTitle.namespace == 0 then --mainspace
			local currentEntityId = mw.wikibase.getEntityIdForCurrentPage()
			if resolveEntity._id(currentEntityId) then
				currentItem = mw.wikibase.getEntity(currentEntityId)
			else --currentEntityId == nil/unresolvable
				return categories[1]
			end
		else
			return ''
		end
		
		if currentItem then --currentItem should not be nil here, but check just in case
			--determine if {{Taxonbar}} is *possibly* missing, or *definitely* missing
			local acceptableInstanceOf_All = { --copied from [[Module:Taxonbar]]
				['Q16521'] = 'taxon',                      --strict
				['Q310890'] = 'monotypic taxon',           --strict
				['Q2568288'] = 'ichnotaxon',               --strict
				['Q23038290'] = 'fossil taxon',            --strict
				['Q47487597'] = 'monotypic fossil taxon',  --strict
				['Q42621'] = 'hybrid',                     --lax
				['Q235536'] = 'incertae sedis',            --lax
				['Q713623'] = 'clade',                     --lax
				['Q848328'] = 'serotype',                  --lax
				['Q857968'] = 'candidatus',                --lax
				['Q17487588'] = 'unavailable combination', --lax
			}
			for _, instanceOfState in pairs ( currentItem:getBestStatements('P31') ) do --instance of
				local instanceOf = instanceOfState.mainsnak.datavalue.value.id
				if acceptableInstanceOf_All[instanceOf] then
					categories[1] = ''
					categories[2] = '[[Category:Taxobox airticles missin a taxonbar]]'
					break
				end
			end
			return table.concat(categories)
		else
			return ''
		end
	end
end

return p