module 'aux'

local event_frame = CreateFrame'Frame'

local listeners, threads = t, t

local thread_id
function public.get_thread_id() return thread_id end

function LOAD()
	event_frame:SetScript('OnUpdate', UPDATE)
	event_frame:SetScript('OnEvent', EVENT)
end

function EVENT()
	for id, listener in listeners do
		if listener.killed then
			listeners[id] = nil
		elseif event == listener.event then
			listener.cb(listener.kill)
		end
	end
end

do
	function UPDATE()
		for _, listener in listeners do
			local event, needed = listener.event, false
			for _, listener in listeners do
				needed = needed or listener.event == event and not listener.killed
			end
			if not needed then
				event_frame:UnregisterEvent(event)
			end
		end

		for id, thread in threads do
			if thread.killed or not thread.k then
				threads[id] = nil
			else
				local k = thread.k
				thread.k = nil
				thread_id = id
				k()
				thread_id = nil
			end
		end
	end
end

do
	local id = 0
	function get_unique_id()
		id = id + 1
		return id
	end
end

function public.kill_listener(listener_id)
	for listener in present(listeners[listener_id]) do
		listener.killed = true
	end
end

function public.kill_thread(thread_id)
	for thread in present(threads[thread_id]) do
		thread.killed = true
	end
end

function public.event_listener(event, cb)
	local listener_id = unique_id
	listeners[listener_id] = T(
		'event', event,
		'cb', cb,
		'kill', vararg-function(arg) if getn(arg) == 0 or arg[1] then kill_listener(listener_id) end end
	)
	event_frame:RegisterEvent(event)
	return listener_id
end

function public.on_next_event(event, callback)
	event_listener(event, function(kill) callback(); kill() end)
end

public.thread = vararg-function(arg)
	local k = tremove(arg, 1)
	local thread_id = unique_id
	threads[thread_id] = T('k', papply(k, unpack(arg)))
	return thread_id
end

public.wait = vararg-function(arg)
	local k = tremove(arg, 1)
	if type(k) == 'number' then
		when(function() k = k - 1 return k <= 1 end, unpack(arg))
	else
		threads[thread_id].k = papply(k, unpack(arg))
	end
end

public.when = vararg-function(arg)
	local c = tremove(arg, 1)
	local k = tremove(arg, 1)
	if c() then
		return k(unpack(arg))
	else
		return wait(when, c, k, unpack(arg))
	end
end