-- Rewind script
-- Will rewind emulation upon pressing X on the joypad
-- Written by: deltaphc

-- Constants
max_states = 100    -- maximum number of states allowed
rewind_interval = 6 -- save state every N frames

states = {}
current_state = 1
rewind_counter = rewind_interval - 1
rewinding = false

input.registerhotkey(1, function()
	rewinding = not rewinding
	
	if rewinding then
		gens.message("Rewind: On")
	else
		gens.message("Rewind: Off")
	end
end)

gens.registerafter( function()
	if rewinding then
		current_state = current_state - 1
		if current_state < 1 then current_state = 1 end

		savestate.load(states[current_state])
		table.remove(states, current_state + 1)
	else
		rewind_counter = rewind_counter + 1

		if rewind_counter == rewind_interval then
			rewind_counter = 1

			if current_state < max_states then
				local state = savestate.create()
				savestate.save(state)
				table.insert(states, state)

				current_state = current_state + 1
			else
				table.remove(states, 1)

				local state = savestate.create()
				savestate.save(state)
				table.insert(states, state)
			end
		end
	end
end)