#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."
	dir = NORTH
	icon_state = "ship"
	appearance_flags = TILE_BOUND|KEEP_TOGETHER|LONG_GLIDE
	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/decisecond.
	var/min_speed = 1/(2 MINUTES)       // Below this, we round speed to 0 to avoid math errors.

	var/position_x						// Pixel coordinates in the world
	var/position_y						// Pixel coordinates in the world.
	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/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.
	var/skill_needed = SKILL_ADEPT  //piloting skill needed to steer it without going in random dir
	var/operator_skill

/obj/effect/overmap/visitable/ship/Initialize()
	. = ..()
	min_speed = round(min_speed, SHIP_MOVE_RESOLUTION)
	max_speed = round(max_speed, SHIP_MOVE_RESOLUTION)
	SSshuttles.ships += src
	position_x = ((loc.x - 1) * WORLD_ICON_SIZE) + (WORLD_ICON_SIZE/2) + pixel_x + 1
	position_y = ((loc.y - 1) * WORLD_ICON_SIZE) + (WORLD_ICON_SIZE/2) + pixel_y + 1

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

/obj/effect/overmap/visitable/ship/relaymove(mob/user, direction, accel_limit)
	accelerate(direction, accel_limit)
	operator_skill = user.get_skill_value(/datum/skill/pilot)

/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: [get_heading_degrees()], 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)

// Get heading in BYOND dir bits
/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

// Get heading in degrees (like a compass heading)
/obj/effect/overmap/visitable/ship/proc/get_heading_degrees()
	return (ATAN2(speed[2], speed[1]) + 360) % 360 // Yes ATAN2(y, x) is correct to get clockwise degrees

/obj/effect/overmap/visitable/ship/proc/adjust_speed(n_x, n_y)
	var/old_still = is_still()
	CHANGE_SPEED_BY(speed[1], n_x)
	CHANGE_SPEED_BY(speed[2], n_y)
	update_icon()
	var/still = is_still()
	if(still == old_still)
		return
	else if(still)
		STOP_PROCESSING(SSprocessing, src)
		for(var/zz in map_z)
			toggle_move_stars(zz)
	else
		START_PROCESSING(SSprocessing, src)
		glide_size = WORLD_ICON_SIZE/max(DS2TICKS(SSprocessing.wait), 1) //Down to whatever decimal
		for(var/zz in map_z)
			toggle_move_stars(zz, fore_dir)

/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(wait)
	var/new_position_x = position_x + (speed[1] * WORLD_ICON_SIZE * wait)
	var/new_position_y = position_y + (speed[2] * WORLD_ICON_SIZE * wait)

	// For simplicity we assume that you can't travel more than one turf per tick.  That would be hella-fast.
	var/new_turf_x = CEILING(new_position_x / WORLD_ICON_SIZE, 1)
	var/new_turf_y = CEILING(new_position_y / WORLD_ICON_SIZE, 1)

	var/new_pixel_x = MODULUS(new_position_x, WORLD_ICON_SIZE) - (WORLD_ICON_SIZE/2) - 1
	var/new_pixel_y = MODULUS(new_position_y, WORLD_ICON_SIZE) - (WORLD_ICON_SIZE/2) - 1

	var/new_loc = locate(new_turf_x, new_turf_y, z)

	position_x = new_position_x
	position_y = new_position_y

	if(new_loc != loc)
		var/turf/old_loc = loc
		Move(new_loc, NORTH, wait)
		if(get_dist(old_loc, loc) > 1)
			pixel_x = new_pixel_x
			pixel_y = new_pixel_y
			return
	animate(src, pixel_x = new_pixel_x, pixel_y = new_pixel_y, time = wait, flags = ANIMATION_END_NOW)

// If we get moved, update our internal tracking to account for it
/obj/effect/overmap/visitable/ship/Moved(atom/old_loc, direction, forced = FALSE)
	. = ..()
	// If moving out of another sector start off centered in the turf.
	if(!isturf(old_loc))
		position_x = (WORLD_ICON_SIZE/2) + 1
		position_y = (WORLD_ICON_SIZE/2) + 1
		pixel_x = 0
		pixel_y = 0
	position_x = ((loc.x - 1) * WORLD_ICON_SIZE) + MODULUS(position_x, WORLD_ICON_SIZE)
	position_y = ((loc.y - 1) * WORLD_ICON_SIZE) + MODULUS(position_y, WORLD_ICON_SIZE)

/obj/effect/overmap/visitable/ship/update_icon()
	if(!is_still())
		icon_state = moving_state
		transform = matrix().Turn(get_heading_degrees())
	else
		icon_state = initial(icon_state)
		transform = null
	..()

/obj/effect/overmap/visitable/ship/set_dir(new_dir)
	return ..(NORTH) // NO! We always face north.

/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
	if(MOVING(speed[1]))
		var/offset = MODULUS(position_x, WORLD_ICON_SIZE)
		var/dist_to_go = (speed[1] > 0) ? (WORLD_ICON_SIZE - offset) : offset
		. = min(., (dist_to_go / abs(speed[1])) * (1/WORLD_ICON_SIZE))
	if(MOVING(speed[2]))
		var/offset = MODULUS(position_y, WORLD_ICON_SIZE)
		var/dist_to_go = (speed[2] > 0) ? (WORLD_ICON_SIZE - offset) : offset
		. = min(., (dist_to_go / abs(speed[2])) * (1/WORLD_ICON_SIZE))
	. = max(., 0)

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

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

/obj/effect/overmap/visitable/ship/proc/get_helm_skill()//delete this mover operator skill to overmap obj
	return operator_skill

/obj/effect/overmap/visitable/ship/populate_sector_objects()
	..()
	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