grunk/src/player/hold_component.gd

class_name HoldComponent extends Node3D
## Component for managing physics object holding

signal held
signal dropped

## Held object position lerp acceleration.
@export var hold_accel := 20.0

## Held object position velocity scale.
@export var hold_speed := 12.0

## The maximum distance the object may be from the hold point before breaking the hold.
@export var max_distance := 3.0

## Temporary linear damping for held objects
@export var hold_damping := 8.0

## Impulse force when throwing an object
@export var throw_force := 100.0

## Temporary collision layer.
@export_flags_3d_physics var hold_collision_layer := 0b01000000

## Temporary collision mask.
@export_flags_3d_physics var hold_collision_physics := 0b01000001

## The object currently being held.
var _held_object: RigidBody3D

var _original_damping: float
var _original_collision_layer: int
var _original_collision_mask: int

@onready var interact_ray: RayCast3D = %InteractRay
@onready var hold_point: Marker3D = %HoldPoint


func attach(prop: RigidBody3D, hold_distance: float) -> void:
	hold_point.position = Vector3(0, 0, -hold_distance)
	hold_point.global_basis = global_basis
	_held_object = prop

	_original_damping = prop.linear_damp
	prop.linear_damp = hold_damping

	_original_collision_layer = prop.collision_layer
	prop.collision_layer = hold_collision_layer

	_original_collision_mask = prop.collision_mask
	prop.collision_mask = hold_collision_physics

	held.emit()


func drop() -> void:
	_held_object.linear_damp = _original_damping
	_held_object.collision_layer = _original_collision_layer
	_held_object.collision_mask = _original_collision_mask
	_held_object = null

	dropped.emit()


func throw() -> void:
	var impulse := -global_basis.z.normalized() * throw_force
	_held_object.apply_central_impulse(impulse)
	drop()


func holding_object() -> bool:
	return !!_held_object


func _unhandled_input(event: InputEvent) -> void:
	if event is InputEventMouseMotion:
		if Input.get_mouse_mode() == Input.MOUSE_MODE_CAPTURED and holding_object():
			print(event)


func _process_hold_controls() -> void:
	if Input.is_action_just_pressed("interact"):
		drop()
	elif Input.is_action_just_pressed("fire"):
		throw()


func _physics_process(delta: float) -> void:
	# Object hold action logic
	if holding_object():
		_process_hold_controls()

	# Held object logic
	if not holding_object():
		return

	var diff := hold_point.global_position - (_held_object.global_position)
	if diff.length() > max_distance:
		drop()
		return

	var weight := 1 - exp(-hold_accel * delta)
	_held_object.linear_velocity = _held_object.linear_velocity.lerp(diff * hold_speed, weight)
	_held_object.global_basis = _held_object.global_basis.slerp(hold_point.global_basis, weight)