#define SHIP_MOVE_RESOLUTION 0.00001
#define MOVING(speed) abs(speed) >= min_speed
#define SANITIZE_SPEED(speed) SIGN(speed) * Clamp(abs(speed), 0, max_speed)
#define CHANGE_SPEED_BY(speed_var, v_diff) \
	v_diff = SANITIZE_SPEED(v_diff);\
	if(!MOVING(speed_var + v_diff)) \
		{speed_var = 0};\
	else \
		{speed_var = SANITIZE_SPEED((speed_var + v_diff)/(1 + speed_var*v_diff/(max_speed ** 2)))}
// Uses Lorentzian dynamics to avoid going too fast.

/obj/effect/overmap/visitable/ship
	name = "generic ship"
	desc = "Space faring vessel."
	icon_state = "ship"
	var/moving_state = "ship_moving"

	var/vessel_mass = 10000             //tonnes, arbitrary number, affects acceleration provided by engines
	var/vessel_size = SHIP_SIZE_LARGE	//arbitrary number, affects how likely are we to evade meteors
	var/max_speed = 1/(1 SECOND)        //"speed of light" for the ship, in turfs/tick.
	var/min_speed = 1/(2 MINUTES)       // Below this, we round speed to 0 to avoid math errors.

	var/list/speed = list(0,0)          //speed in x,y direction
	var/last_burn = 0                   //worldtime when ship last acceleated
	var/burn_delay = 1 SECOND           //how often ship can do burns
	var/list/last_movement = list(0,0)  //worldtime when ship last moved in x,y direction
	var/fore_dir = NORTH                //what dir ship flies towards for purpose of moving stars effect procs

	var/list/engines = list()
	var/engines_state = 0 //global on/off toggle for all engines
	var/thrust_limit = 1  //global thrust limit for all engines, 0..1
	var/halted = 0        //admin halt or other stop.

/obj/effect/overmap/visitable/ship/Initialize()
	. = ..()
	min_speed = round(min_speed, SHIP_MOVE_RESOLUTION)
	max_speed = round(max_speed, SHIP_MOVE_RESOLUTION)
	SSshuttle.ships += src
	START_PROCESSING(SSprocessing, src)

/obj/effect/overmap/visitable/ship/Destroy()
	STOP_PROCESSING(SSprocessing, src)
	SSshuttle.ships -= src
	. = ..()

/obj/effect/overmap/visitable/ship/relaymove(mob/user, direction, accel_limit)
	accelerate(direction, accel_limit)

/obj/effect/overmap/visitable/ship/proc/is_still()
	return !MOVING(speed[1]) && !MOVING(speed[2])

/obj/effect/overmap/visitable/ship/get_scan_data(mob/user)
	. = ..()
	if(!is_still())
		. += "<br>Heading: [dir2angle(get_heading())], speed [get_speed() * 1000]"

//Projected acceleration based on information from engines
/obj/effect/overmap/visitable/ship/proc/get_acceleration()
	return round(get_total_thrust()/get_vessel_mass(), SHIP_MOVE_RESOLUTION)

//Does actual burn and returns the resulting acceleration
/obj/effect/overmap/visitable/ship/proc/get_burn_acceleration()
	return round(burn() / get_vessel_mass(), SHIP_MOVE_RESOLUTION)

/obj/effect/overmap/visitable/ship/proc/get_vessel_mass()
	. = vessel_mass
	for(var/obj/effect/overmap/visitable/ship/ship in src)
		. += ship.get_vessel_mass()

/obj/effect/overmap/visitable/ship/proc/get_speed()
	return round(sqrt(speed[1] ** 2 + speed[2] ** 2), SHIP_MOVE_RESOLUTION)

/obj/effect/overmap/visitable/ship/proc/get_heading()
	var/res = 0
	if(MOVING(speed[1]))
		if(speed[1] > 0)
			res |= EAST
		else
			res |= WEST
	if(MOVING(speed[2]))
		if(speed[2] > 0)
			res |= NORTH
		else
			res |= SOUTH
	return res

/obj/effect/overmap/visitable/ship/proc/adjust_speed(n_x, n_y)
	CHANGE_SPEED_BY(speed[1], n_x)
	CHANGE_SPEED_BY(speed[2], n_y)
	for(var/zz in map_z)
		if(is_still())
			toggle_move_stars(zz)
		else
			toggle_move_stars(zz, fore_dir)
	update_icon()

/obj/effect/overmap/visitable/ship/proc/get_brake_path()
	if(!get_acceleration())
		return INFINITY
	if(is_still())
		return 0
	if(!burn_delay)
		return 0
	if(!get_speed())
		return 0
	var/num_burns = get_speed()/get_acceleration() + 2 //some padding in case acceleration drops form fuel usage
	var/burns_per_grid = 1/ (burn_delay * get_speed())
	return round(num_burns/burns_per_grid)

/obj/effect/overmap/visitable/ship/proc/decelerate()
	if(((speed[1]) || (speed[2])) && can_burn())
		if (speed[1])
			adjust_speed(-SIGN(speed[1]) * min(get_burn_acceleration(),abs(speed[1])), 0)
		if (speed[2])
			adjust_speed(0, -SIGN(speed[2]) * min(get_burn_acceleration(),abs(speed[2])))
		last_burn = world.time

/obj/effect/overmap/visitable/ship/proc/accelerate(direction, accel_limit)
	if(can_burn())
		last_burn = world.time
		var/acceleration = min(get_burn_acceleration(), accel_limit)
		if(direction & EAST)
			adjust_speed(acceleration, 0)
		if(direction & WEST)
			adjust_speed(-acceleration, 0)
		if(direction & NORTH)
			adjust_speed(0, acceleration)
		if(direction & SOUTH)
			adjust_speed(0, -acceleration)

/obj/effect/overmap/visitable/ship/process()
	if(!halted && !is_still())
		var/list/deltas = list(0,0)
		for(var/i=1, i<=2, i++)
			if(MOVING(speed[i]) && world.time > last_movement[i] + 1/abs(speed[i]))
				deltas[i] = SIGN(speed[i])
				last_movement[i] = world.time
		var/turf/newloc = locate(x + deltas[1], y + deltas[2], z)
		if(newloc)
			Move(newloc)
			handle_wraparound()
		update_icon()

/obj/effect/overmap/visitable/ship/update_icon()
	if(!is_still())
		icon_state = moving_state
		dir = get_heading()
	else
		icon_state = initial(icon_state)
	..()

/obj/effect/overmap/visitable/ship/proc/burn()
	for(var/datum/ship_engine/E in engines)
		. += E.burn()

/obj/effect/overmap/visitable/ship/proc/get_total_thrust()
	for(var/datum/ship_engine/E in engines)
		. += E.get_thrust()

/obj/effect/overmap/visitable/ship/proc/can_burn()
	if(halted)
		return 0
	if (world.time < last_burn + burn_delay)
		return 0
	for(var/datum/ship_engine/E in engines)
		. |= E.can_burn()

//deciseconds to next step
/obj/effect/overmap/visitable/ship/proc/ETA()
	. = INFINITY
	for(var/i=1, i<=2, i++)
		if(MOVING(speed[i]))
			. = min(last_movement[i] - world.time + 1/abs(speed[i]), .)
	. = max(.,0)

/obj/effect/overmap/visitable/ship/proc/handle_wraparound()
	var/nx = x
	var/ny = y
	var/low_edge = 1
	var/high_edge = current_map.overmap_size - 1

	if((dir & WEST) && x == low_edge)
		nx = high_edge
	else if((dir & EAST) && x == high_edge)
		nx = low_edge
	if((dir & SOUTH)  && y == low_edge)
		ny = high_edge
	else if((dir & NORTH) && y == high_edge)
		ny = low_edge
	if((x == nx) && (y == ny))
		return //we're not flying off anywhere

	var/turf/T = locate(nx,ny,z)
	if(T)
		forceMove(T)

/obj/effect/overmap/visitable/ship/proc/halt()
	adjust_speed(-speed[1], -speed[2])
	halted = 1

/obj/effect/overmap/visitable/ship/proc/unhalt()
	if(!SSshuttle.overmap_halted)
		halted = 0

/obj/effect/overmap/visitable/ship/Bump(var/atom/A)
	if(istype(A,/turf/unsimulated/map/edge))
		handle_wraparound()
	..()

/obj/effect/overmap/visitable/ship/populate_sector_objects()
	..()
	for(var/obj/machinery/computer/ship/S in SSmachinery.all_machines)
		S.attempt_hook_up(src)
	for(var/datum/ship_engine/E in ship_engines)
		if(check_ownership(E.holder))
			engines |= E

/obj/effect/overmap/visitable/ship/proc/get_landed_info()
	return "This ship cannot land."

#undef MOVING
#undef SANITIZE_SPEED
#undef CHANGE_SPEED_BY