/ld26

-- Class: Timer

-- A timer allows delayed or periodic execution of a function according

-- to elapsed time in an app. In order for it to work properly, it must

-- receive update events, so it must be added somewhere in the current

-- view or app. If you are using the <View> class, then this is already

-- done for you; one is created as the View's timer property.

Timer = Sprite:extend{

	timers = {},

	visible = false,

	active = false,

	solid = false,

	-- Method: wait

	-- Method: after

	-- Delays a function call after a certain a mount of time.

	--

	-- Arguments:

	--		* delay - how long to wait, in seconds

	--		* func - function to call

	--

	-- Returns:

	--		A <Promise> that is fulfilled after the function is called

	after = function (self, delay, func)

		if STRICT then

			assert(type(func) == 'function', 'func property of timer must be a function')

			assert(type(delay) == 'number', 'delay must be a number')

			if delay <= 0 then

				local info = debug.getinfo(2, 'Sl')

				print('Warning: timer delay is ' .. delay .. ', will be triggered immediately (' .. 

					  info.short_src .. ', line ' .. info.currentline .. ')')

			end

		end

		self.active = true

		local promise = Promise:new()

		table.insert(self.timers, { func = func, timeLeft = delay, promise = promise })

		return promise

	end,

	-- Method: every

	-- Repeatedly makes a function call. To stop these calls from

	-- happening in the future, you must call stop().

	--

	-- Arguments:

	--		* delay - how often to make the function call, in seconds

	--		* func - function to call

	--

	-- Returns:

	--		nothing

	every = function (self, delay, func)

		if STRICT then

			assert(type(func) == 'function', 'func property of timer must be a function')

			assert(type(delay) == 'number', 'delay must be a number')

			if delay <= 0 then

				local info = debug.getinfo(2, 'Sl')

				print('Warning: timer delay is ' .. delay .. ', will be triggered immediately (' .. 

					  info.short_src .. ', line ' .. info.currentline .. ')')

			end

		end

		self.active = true

		table.insert(self.timers, { func = func, timeLeft = delay, interval = delay })

	end,

	-- Method: status

	-- Returns how much time is left before a function call is scheduled.

	--

	-- Arguments:

	--		func - the function that is queued

	--

	-- Returns:

	--		the time left until the soonest call matching these arguments,

	--		or nil if there is no call scheduled

	status = function (self, func, bind, arg)

		local result

		for _, t in pairs(self.timers) do

			if t.func == func and (not result or result < t.timeLeft) then

			   result = t.timeLeft

			end

		end

		return result

	end,

	-- Method: stop

	-- Stops a timer from executing. The promise belonging to it is failed. 

	-- If there is no function associated with this timer, then this has no effect.

	--

	-- Arguments:

	--		func - function to stop; if omitted, stops all timers

	--

	-- Returns:

	--		nothing

	stop = function (self, func, bind)

		local found = false

		for i, timer in ipairs(self.timers) do

			if not func or timer.func == func then

				if timer.promise then

					timer.promise:fail('Timer stopped')

				end

				table.remove(self.timers, i)

				found = true

			end

		end

		if STRICT and not found then

			local info = debug.getinfo(2, 'Sl')

			print('Warning: asked to stop a timer on a function that was not queued (' ..

				  info.short_src .. ', line ' .. info.currentline .. ')')

		end

	end,

	update = function (self, elapsed)

		for i, timer in ipairs(self.timers) do

			timer.timeLeft = timer.timeLeft - elapsed

			if timer.timeLeft <= 0 then

				if timer.promise then

					timer.promise:fulfill(timer.func())

				else

					timer.func()

				end

				if timer.interval then

					timer.timeLeft = timer.interval

					keepActive = true

				else

					table.remove(self.timers, i)

				end

			else

				keepActive = true

			end

		end

		self.active = (#self.timers > 0)

	end,

	__tostring = function (self)

		local result = 'Timer ('

		if self.active then

			result = result .. 'active, '

			result = result .. #self.timers .. ' timers running'

		else

			result = result .. 'inactive'

		end

		return result .. ')'

	end

}