local function throttle(func, tg_throttle)
    local tg = 0
    if not tg_throttle or tg_throttle == 0 then
        return function(...)
            local t = time_global()
            if t ~= tg then
                tg = t
                return func(...)
            end
        end
    else
        return function(...)
            local t = time_global()
            if t < tg then return end
            tg = t + tg_throttle
            return func(...)
        end
    end
end

local fpCamEffectorId = 10005
local fpCamEffectorTg
local fpCamEffectorTime = 15000 --Actual time is about half of it
local fpCamEffectorMin = 0.005
function getFpCamEffectorId()
	return fpCamEffectorId
end

-- Throttle changing sound since it is smoothed in the engine
setSound = throttle(function(v)
	level.set_snd_volume(v)
	if level.set_music_volume then level.set_music_volume(v) end
end, 500)

function fadeToBlack()
	level.set_snd_volume(0)
	if level.set_music_volume then level.set_music_volume(0) end
	level.set_pp_effector_factor(getFpCamEffectorId(), 1)
end

function startCam()
	level.add_pp_effector("black_infinite.ppe", getFpCamEffectorId(), true)
	level.set_pp_effector_factor(getFpCamEffectorId(), fpCamEffectorMin)
	fpCamEffectorTg = time_global()
	AddUniqueCall(updateCam)
	RegisterScriptCallback("main_menu_on_init", main_menu_on_init)
	RegisterScriptCallback("main_menu_on_quit", main_menu_on_quit)
end

function reset()
	level.set_snd_volume(1)
	if level.set_music_volume then level.set_music_volume(1) end
	exec_console_cmd("time_factor 1")
end

function main_menu_on_init()
	reset()
end

function main_menu_on_quit()
	reset()
	level.remove_pp_effector(getFpCamEffectorId())
	RemoveUniqueCall(updateCam)
	UnregisterScriptCallback("main_menu_on_init", main_menu_on_init)
	UnregisterScriptCallback("main_menu_on_quit", main_menu_on_quit)
end

function actor_on_first_update()
	reset()
end

function updateCam()
	if not db.actor then
		fadeToBlack()
		return
	end

	local k = math.min(1, normalize(time_global(), fpCamEffectorTg, fpCamEffectorTg + fpCamEffectorTime) + fpCamEffectorMin)

	if k == 1 then
		fadeToBlack()
		return
	end

	-- Fade out sounds
	local sound_k = math.max(0, 1 - normalize(k, 0, 0.6))
	setSound(sound_k)

	-- Time factor change
	local time_k = 1 - 0.4 * math.min(1, normalize(k, 0, 0.6))
	exec_console_cmd(("time_factor %s"):format(time_k))

	-- Pulsating effect
	k = (math.sin(k * (math.pi / 2) * 48)) / 30 + k
	level.set_pp_effector_factor(getFpCamEffectorId(), k)
end

function checkCam()
	RemoveTimeEvent("true_first_person_death", "checkCam")
	CreateTimeEvent("true_first_person_death", "checkCam", 0, function(tg)
		if not get_console_cmd(1, "first_person_death") then
			return true
		end

		if time_global() - tg > 5000 then
			return true
		end

		if not db.actor then
			return true
		end

		if db.actor:alive() then
			return false
		end

		startCam()
		return true
	end, time_global())
end

function on_key_press(dik)
	if dik == DIK_keys.DIK_K then
		if db.actor:alive() then
			db.actor:kill(db.actor)
		end
	end
end

function on_game_start()
	RegisterScriptCallback("actor_on_first_update", actor_on_first_update)
	RegisterScriptCallback("actor_on_before_death", checkCam)
	-- RegisterScriptCallback("on_key_press", on_key_press)
end