local util = {}

util.current_engine = ""
util.current_engine_index = nil
util.current_xkbmap = ""


-- Update current_engine and current_engine index,
-- call callback() when done.
util.get = function(callback)
	-- Get current ibus engine
	awful.spawn.easy_async(
		"ibus engine",
		function(stdout, stderr, exitreason, exitcode)
			util.current_engine = string.gsub(stdout, "\n", "")
			util.current_engine_index = nil

			-- Find the current engine's index in config.ibus.language_list.
			-- If it is not there, util.current_engine_index will be nil.
			for k, v in pairs(config.ibus.language_list) do
				if (v["ibus_engine"] == util.current_engine) then
					util.current_engine_index = k
				end
			end

			-- Get current xkbmap
			awful.spawn.easy_async(
				"setxkbmap -query",
				function(stdout, stderr, exitreason, exitcode)
					util.current_xkbmap = string.match(stdout, "layout:%s+(%w+)")

					-- When everything is done, run callback if it is given.
					if callback then
						callback()
					end
				end
			)
		end
	)
end


-- Set engine to language_index.
-- calls util.get(callback) when done.
util.set = function(language_index, callback)
	-- engine is an index of the language list above

	local engine = config.ibus.language_list[language_index]["ibus_engine"]

	-- Get required engine, if one is given
	local requires_engine
	for k, v in pairs(config.ibus.language_list) do
		if (v["ibus_engine"] == engine) then
			requires_engine = v["requires_engine"]
		end
	end

	-- If a required xkb engine is given, but it is not active, switch to it before switching to the target
	if (requires_engine ~= util.current_engine) and (requires_engine ~= nil) then
		awful.spawn.easy_async(
			"ibus engine " .. requires_engine,
			function(stdout, stderr, exitreason, exitcode)
				awful.spawn.easy_async(
					"ibus engine " .. engine,
					function(stdout, stderr, exitreason, exitcode)
						util.get(callback)
					end
				)
			end
		)
	else
		awful.spawn.easy_async(
			"ibus engine " .. engine,
			function(stdout, stderr, exitreason, exitcode)
				util.get(callback)
			end
		)
	end
end


-- Calls util.set(callback) with next language in list.
util.next = function(callback)
	if (util.current_engine_index == nil) or (util.current_engine_index == #config.ibus.language_list) then
		util.current_engine_index = 1
	else
		util.current_engine_index = util.current_engine_index + 1
	end
	util.set(util.current_engine_index, callback)
end



return util