class_name ShipCameraRig
extends Node3D

# Third-person camera for a Ship. Ball Cam keeps the ship between the camera
# and the ball; Ship Cam chases behind the ship. The game mode spawns this
# rig and assigns `target` after spawning the player's ship — ships
# themselves are camera-free (a headless/AI ship never needs one).

signal camera_mode_changed(is_ball_cam: bool)

@export var camera_distance := 8.0
@export var camera_height := 3.0
@export var camera_smoothing := 10.0
@export var orbit_smoothing := 6.0   # How fast the camera swings around the ship in ball cam
@export var look_smoothing := 20.0   # How fast the camera re-centres its look target
@export var min_camera_height := 1.0 # Keeps the camera from dipping through the arena floor

var target: Ship
var ball_cam_enabled := true

@onready var camera: Camera3D = $Camera3D

var _ball: Node3D
# Smoothed horizontal direction from ball to ship; the ball-cam orbits along
# this so the camera swings smoothly around the ship instead of chasing a
# raw position (which whips when ball and ship are close together).
var _orbit_dir := Vector3.BACK


func _ready():
	# Group lets the HUD discover the rig for the camera-mode instrument
	add_to_group("ship_camera")


func _input(event):
	if event.is_action_pressed("ui_accept"):  # Enter key
		ball_cam_enabled = !ball_cam_enabled
		camera_mode_changed.emit(ball_cam_enabled)


func _physics_process(delta):
	if not is_instance_valid(target):
		return
	var ball := _get_ball()
	if ball_cam_enabled and ball:
		_update_ball_cam(delta, ball)
	else:
		_update_ship_cam(delta)


func _get_ball() -> Node3D:
	if not is_instance_valid(_ball):
		_ball = get_tree().get_first_node_in_group("ball")
	return _ball


func _update_ball_cam(delta, ball: Node3D):
	# Ball cam keeps the ship between the camera and the ball: the camera sits
	# on the ball→ship line (horizontal component only), looking at the ball,
	# so the ship stays low-centre in frame and the ball stays centred.
	var ship_pos: Vector3 = target.global_transform.origin
	var ball_pos: Vector3 = ball.global_transform.origin

	# Smooth the orbit direction in angle space rather than lerping the camera
	# position directly — when ball and ship pass close to each other the raw
	# direction flips instantly, and slerping the direction turns that into a
	# controlled swing around the ship. The vertical component is dropped so
	# a ball flying overhead pitches the camera up instead of shoving it into
	# the floor or the sky.
	var flat := Vector3(ship_pos.x - ball_pos.x, 0.0, ship_pos.z - ball_pos.z)
	if flat.length() > 0.25:
		var t := 1.0 - exp(-orbit_smoothing * delta)  # frame-rate independent
		# Both directions are horizontal, so swing about the exact UP axis.
		# (Vector3.slerp derives its axis from the cross product, which
		# degenerates when the directions are nearly parallel — the common
		# case here — and spams normalization errors every frame.)
		var swing := _orbit_dir.signed_angle_to(flat.normalized(), Vector3.UP)
		_orbit_dir = _orbit_dir.rotated(Vector3.UP, swing * t).normalized()

	var camera_target_pos := ship_pos + _orbit_dir * camera_distance + Vector3.UP * camera_height
	camera_target_pos.y = maxf(camera_target_pos.y, min_camera_height)

	var pos_t := 1.0 - exp(-camera_smoothing * delta)
	camera.global_position = camera.global_position.lerp(camera_target_pos, pos_t)

	# Look slightly above the ball's centre; look smoothing is faster than
	# position smoothing so the ball never drifts out of frame while the
	# camera is still swinging into place.
	_smooth_look_at(ball_pos + Vector3.UP * 0.5, delta)


func _update_ship_cam(delta):
	# In ship cam, camera follows and looks in the same direction as the ship
	var ship_pos: Vector3 = target.global_transform.origin
	var ship_forward: Vector3 = -target.global_transform.basis.z

	# Position camera behind and above the ship
	var camera_target_pos := ship_pos - ship_forward * camera_distance + Vector3.UP * camera_height
	camera_target_pos.y = maxf(camera_target_pos.y, min_camera_height)

	var pos_t := 1.0 - exp(-camera_smoothing * delta)
	camera.global_position = camera.global_position.lerp(camera_target_pos, pos_t)

	# Look ahead of the ship
	_smooth_look_at(ship_pos + ship_forward * 10.0, delta)


func _smooth_look_at(point: Vector3, delta: float) -> void:
	var to_point := point - camera.global_position
	if to_point.length() < 0.1:
		return
	var dir := to_point.normalized()
	if absf(dir.dot(Vector3.UP)) > 0.99:
		return  # Nearly vertical: looking_at would be degenerate, keep last frame
	var look_basis := Basis.looking_at(dir, Vector3.UP)
	var look_t := 1.0 - exp(-look_smoothing * delta)
	camera.global_basis = camera.global_basis.slerp(look_basis, look_t).orthonormalized()