-- Define the initial machine groups and allowed tiles for each group.
local function build_allowed_entities()
	local allowed = {}
	local filters = {
		--{ filter = "subgroup", subgroup = "inserter" },
		{ filter = "subgroup", subgroup = "circuit-network" },
	}
	table.insert(filters, {
		filter = "place-result",
		elem_filters = {
			{ filter = "type", type = "inserter" }
		}
	})
	
	if script.active_mods["aai-containers"] then
		table.insert(filters, { filter = "subgroup", subgroup = "container-1" })
	end
	--[[
	if script.active_mods["kry-inserters"] then
		table.insert(filters, { filter = "subgroup", subgroup = "shinyinserter1" })
		table.insert(filters, { filter = "subgroup", subgroup = "shinyinserter2" })
	end]]--

	-- get items from filters
	local items = {}
	if filters[1] then
		items = prototypes.get_item_filtered(filters)
	end

	for _, item in pairs(items) do
		if item.place_result then
			allowed[item.place_result.name] = true
		end
	end

	-- storage group but only chest
	local storage_filters = { { filter = "subgroup", subgroup = "storage" } }
	local storage_items = prototypes.get_item_filtered(storage_filters)
	for _, item in pairs(storage_items) do
		if item.place_result and string.find(item.name, "chest") then
			allowed[item.place_result.name] = true
		end
	end

	-- logistic group but only chest
	local logistic_filters = { { filter = "subgroup", subgroup = "logistic-network" } }
	local logistic_items = prototypes.get_item_filtered(logistic_filters)
	for _, item in pairs(logistic_items) do
		if item.place_result and string.find(item.name, "chest") then
			allowed[item.place_result.name] = true
		end
	end

	-- logistic group but only chest
	local belt_filters = { { filter = "subgroup", subgroup = "belt" } }
	local belt_items = prototypes.get_item_filtered(belt_filters)
	for _, item in pairs(belt_items) do
		if item.place_result and string.find(item.name, "transport") then
			allowed[item.place_result.name] = true
		end
	end

	-- additional stuff
	allowed["gun-turret"] = true
	allowed["heavy-gun-turret"] = true
	allowed["flamethrower-turret"] = true
	allowed["rocket-turret"] = true
	allowed["pipe"] = true
	allowed["steel-chest"] = true
	allowed["barreling-machine"] = true
	allowed["radar"] = true
	allowed["canex-excavator"] = true
	allowed["entity-ghost"] = true
	allowed["pump"] = true
	allowed["long-range-delivery-drone-request-depot"] = true
	allowed["cargo_ship"] = true
	allowed["cargo_ship_engine"] = true
	allowed["oil_tanker"] = true
	allowed["indep-boat"] = true
	allowed["boat_engine"] = true
	allowed["oil_rig"] = true
	allowed["or_power_electric"] = true
	allowed["or_pole"] = true
	allowed["or_radar"] = true
	allowed["or_tank"] = true

	return allowed
end