local timer = require "util.timer";

local setmetatable = setmetatable;

local os_time = os.time;

module "watchdog"

local watchdog_methods = {};

local watchdog_mt = { __index = watchdog_methods };

function new(timeout, callback)

	local watchdog = setmetatable({ timeout = timeout, last_reset = os_time(), callback = callback }, watchdog_mt);

	timer.add_task(timeout+1, function (current_time)

		local last_reset = watchdog.last_reset;

		if not last_reset then

			return;

		end

		local time_left = (last_reset + timeout) - current_time;

		if time_left < 0 then

			return watchdog:callback();

		end

		return time_left + 1;

	end);

	return watchdog;

end

function watchdog_methods:reset()

	self.last_reset = os_time();

end

function watchdog_methods:cancel()

	self.last_reset = nil;

end

return _M;