extends Node3D
## Playable Box3D/Jolt/GodotPhysics pinball testbed.
## Z = left flipper, / = right flipper, Space = plunger, R = reset ball.

const FLIP_SPEED := 25.0
const REST_SPEED := 8.0
const PLUNGE_IMPULSE := 0.32  # ~4 m/s on the 80 g ball
const BUMPER_IMPULSE := 0.12

@onready var ball: RigidBody3D = $Ball
@onready var left_joint: HingeJoint3D = $LeftFlipperJoint
@onready var right_joint: HingeJoint3D = $RightFlipperJoint

var _ball_start: Transform3D

func _ready() -> void:
	_ball_start = ball.transform
	print("physics engine: ", ProjectSettings.get_setting("physics/3d/physics_engine"))
	$Drain.body_entered.connect(_on_drain)
	$BumperArea.body_entered.connect(_on_bumper)
	if OS.get_environment("PINBALL_AUTOTEST") == "1":
		_autotest()

## Headless check that the real table flippers flip: hold both motors at flip
## speed for half a second and report how far each flipper swung.
func _autotest() -> void:
	set_physics_process(false)
	var lf: RigidBody3D = $LeftFlipper
	var rf: RigidBody3D = $RightFlipper
	var l0 := lf.rotation.y
	var r0 := rf.rotation.y
	left_joint.set_param(HingeJoint3D.PARAM_MOTOR_TARGET_VELOCITY, FLIP_SPEED)
	right_joint.set_param(HingeJoint3D.PARAM_MOTOR_TARGET_VELOCITY, -FLIP_SPEED)
	for i in 30:
		await get_tree().physics_frame
	print("AUTOTEST left_swing_deg=%.1f right_swing_deg=%.1f" % [
		rad_to_deg(angle_difference(l0, lf.rotation.y)),
		rad_to_deg(angle_difference(r0, rf.rotation.y))])
	get_tree().quit(0)

func _physics_process(_delta: float) -> void:
	var left := Input.is_physical_key_pressed(KEY_Z)
	var right := Input.is_physical_key_pressed(KEY_SLASH)
	left_joint.set_param(HingeJoint3D.PARAM_MOTOR_TARGET_VELOCITY, FLIP_SPEED if left else -REST_SPEED)
	right_joint.set_param(HingeJoint3D.PARAM_MOTOR_TARGET_VELOCITY, -FLIP_SPEED if right else REST_SPEED)
	if Input.is_physical_key_pressed(KEY_SPACE) and _ball_in_lane():
		ball.apply_central_impulse(Vector3(0, 0, -PLUNGE_IMPULSE))
	if Input.is_physical_key_pressed(KEY_R):
		_reset_ball()

func _ball_in_lane() -> bool:
	return ball.position.x > 0.21 and ball.position.z > 0.30 \
		and ball.linear_velocity.length() < 0.05

func _on_drain(body: Node3D) -> void:
	if body == ball:
		_reset_ball.call_deferred()

func _on_bumper(body: Node3D) -> void:
	if body != ball:
		return
	var bumper: StaticBody3D = $Bumper
	var dir := ball.global_position - bumper.global_position
	dir.y = 0.0
	if dir.length() < 0.001:
		dir = Vector3(0, 0, 1)
	ball.apply_central_impulse(dir.normalized() * BUMPER_IMPULSE)

func _reset_ball() -> void:
	ball.linear_velocity = Vector3.ZERO
	ball.angular_velocity = Vector3.ZERO
	ball.transform = _ball_start