--local movingActive = 673 -- this value is actually not random, but carefully calculated , src value:  0,1484375
local miningActive = 100

function init()
	if not global.Superhot then
		global.Superhot = {}
	end
	if not global.Superhot.playermovement then
		global.Superhot.playermovement = {}
	end
end

function getDist(mov)
	return math.sqrt((mov[1] * mov[1]) + (mov[2] * mov[2]))
end

-- caps the speed using a logarithmic function, is undefined for x <= 0!
function movementcap(x)
	return (75.88 * math.log(x)) + 244
end

script.on_event({defines.events.on_tick},
	function (e)
	init() -- init variables TODO: do somewhere else!
	local activeMax = 0
	local lastplayer -- just for DEBUG
	for index,player in pairs(game.connected_players) do  --loop through all online players on the server
		lastplayer = player
		if player.valid and player.connected and player.character then
			local active = 0
			-- is mining?
			if player.mining_state.mining then
				active = miningActive
			end

			--is moving
			local newpos = player.position
			local oldpos = global.Superhot.playermovement[player.index]
			local mov = {0,0}
			if oldpos ~= nil then
				mov = {oldpos.x - newpos.x, oldpos.y - newpos.y}
				
				local dist = getDist(mov)
				if dist > 0 then
					active = active + movementcap(dist)
				end
			end

			--update movement
			global.Superhot.playermovement[player.index] = newpos

			--update max
			if active > activeMax then
				activeMax = active
			end
		end
	end
	
	local goal = activeMax/100.0
	local diff = goal - game.speed
	
	-- make acceleration smoother
	if diff > 0.2 or diff < -0.2 then
		diff = diff / 2.0
	end
	goal = game.speed + diff

	--clip to upper and lower bound
	if goal < 0.1 then
		goal = 0.1
	elseif goal > 10 then
		goal = 10
	end
	
	--actually set it
	game.speed = goal
	end
)

-- spped modifyer: game.speed=1
-- freeze time: game.player.surface.freeze_daytime=true

-- defines.events.on_pre_player_mined_item