mesecon.queue.actions={} -- contains all ActionQueue actions

function mesecon.queue:add_function(name, func)
	mesecon.queue.funcs[name] = func
end

-- If add_action with twice the same overwritecheck and same position are called, the first one is overwritten
-- use overwritecheck nil to never overwrite, but just add the event to the queue
function mesecon.queue:add_action(pos, func, params, time, overwritecheck)
	-- Create Action Table:
	time = time or 0 -- time <= 0 --> execute, time > 0 --> wait time until execution
	action = {	pos=pos,
			func=func,
			params=mesecon:tablecopy(params),
			time=time,
			owcheck=overwritecheck}

	--print(dump(action))
	-- if not using the queue, (MESECONS_GLOBALSTEP off), just execute the function an we're done
	if not MESECONS_GLOBALSTEP then
		mesecon.queue:execute(action)
		return
	end

	-- Otherwise, add the action to the queue
	if overwritecheck then -- check if old action has to be overwritten / removed:
		for i, ac in ipairs(mesecon.queue.actions) do
			if(mesecon:cmpPos(pos, action.pos)
			and mesecon:cmpAny(overwritecheck, ac.owcheck)) then
				table.remove(mesecon.queue.actions, i)
				break
			end
		end
	end

	table.insert(mesecon.queue.actions, action)
end

-- execute the stored functions on a globalstep
-- if however, the pos of a function is not loaded (get_node_or_nil == nil), do NOT execute the function
-- this makes sure that resuming mesecons circuits when restarting minetest works fine
-- However, even that does not work in some cases, that's why we delay the time the globalsteps
-- start to be execute by 5 seconds
local m_time = 0
minetest.register_globalstep(function (dtime)
	m_time = m_time + dtime
	if (m_time < 5) then return end -- don't even try if server has not been running for 2 seconds
	local actions = mesecon:tablecopy(mesecon.queue.actions)
	mesecon.queue.actions = {}

	for i, action in ipairs(actions) do
		if action.time > 0 then
			action.time = action.time - dtime
			table.insert(mesecon.queue.actions, action) -- will be handled another time
		else -- execute and remove
			mesecon.queue:execute(action)
		end
	end
end)

function mesecon.queue:execute(action)
	mesecon.queue.funcs[action.func](action.pos, unpack(action.params))
end


-- Store and read the ActionQueue to / from a file
-- so that upcoming actions are remembered when the game
-- is restarted

local wpath = minetest.get_worldpath()
local function file2table(filename)
	local f = io.open(filename, "r")
	if f==nil then return {} end
	local t = f:read("*all")
	f:close()
	if t=="" or t==nil then return {} end
	return minetest.deserialize(t)
end

local function table2file(filename, table)
	local f = io.open(filename, "w")
	f:write(minetest.serialize(table))
	f:close()
end

mesecon.queue.actions = file2table(wpath.."/mesecon_actionqueue")

minetest.register_on_shutdown(function()
	mesecon.queue.actions = table2file(wpath.."/mesecon_actionqueue", mesecon.queue.actions)
end)