class_name GrunkBeast extends CharacterBody3D
## Grunk beast controller

#region Constants
signal state_changed(new_state: State)

enum State {
	UNKNOWN,
	LURKING,
	STALKING,
	PURSUIT,
}

const LURK_POINT_GROUP := "LurkPoint"
const STALKING_SOUND_LIMIT := 14.0
const IDLE_EPSILON := 0.001
#endregion

#region Exported Properties
@export var lurk_spontaneity := 0.02
@export var base_speed := 60.0
@export var pursuit_speed := 180.0
@export var initial_state := State.LURKING
#endregion

#region Member Variables
var gravity: Vector3 = (
	ProjectSettings.get_setting("physics/3d/default_gravity")
	* ProjectSettings.get_setting("physics/3d/default_gravity_vector")
)

var state: State:
	set(value):
		if state != value:
			_on_state_change(value)
		state = value

var pathfinding := true

@onready var nav_agent: NavigationAgent3D = %NavAgent
@onready var stalking_timeout: Timer = %StalkingTimeout
@onready var idle_timer: Timer = %IdleTimer
#endregion

#region Character Controller


func get_speed() -> float:
	match state:
		State.PURSUIT:
			return pursuit_speed
	return base_speed


func _physics_process(delta: float) -> void:
	var motion := Vector3.ZERO

	if pathfinding:
		var path_pos := nav_agent.get_next_path_position()
		var relative_pos := path_pos - global_position
		motion = relative_pos.normalized() * get_speed() * delta

	velocity.x = motion.x
	velocity.z = motion.z

	if not is_on_floor():
		velocity += gravity * delta

	if velocity.length_squared() > IDLE_EPSILON:
		idle_timer.start()

	move_and_slide()


#endregion

#region State Machine


func _ready() -> void:
	state = initial_state


func _current_path_shorter_than(limit: float) -> bool:
	var limit_sq := limit * limit
	var length_sq := 0.0
	var last_pos := global_position

	for waypoint: Vector3 in nav_agent.get_current_navigation_path().slice(
		nav_agent.get_current_navigation_path_index()
	):
		# Using distance squared to save a sqrt instruction
		length_sq += last_pos.distance_squared_to(waypoint)
		if length_sq > limit_sq:
			return false
		last_pos = waypoint

	return true


func _set_new_lurk_point() -> void:
	@warning_ignore("unsafe_cast")
	var next_lurk_point := get_tree().get_nodes_in_group(LURK_POINT_GROUP).pick_random() as Node3D
	if next_lurk_point:
		nav_agent.target_position = next_lurk_point.global_position
	else:
		push_warning(self, " tried to lurk, but couldn't find a lurk point!")


## Lurking routine
func lurk() -> void:
	if nav_agent.is_target_reached() or randf() < lurk_spontaneity:
		_set_new_lurk_point()


## Stalking routine
func stalk() -> void:
	pass


## Pursuit routine
func pursue() -> void:
	if Player.instance:
		nav_agent.target_position = Player.instance.global_position


func _on_state_change(new_state: State) -> void:
	match new_state:
		State.LURKING:
			_set_new_lurk_point()
		State.STALKING:
			stalking_timeout.start()

	state_changed.emit(new_state)


func update_behavior() -> void:
	match state:
		State.UNKNOWN:
			state = State.LURKING
			update_behavior()
		State.LURKING:
			lurk()
		State.STALKING:
			stalk()
		State.PURSUIT:
			pursue()


func on_sound_detected(source: Vector3) -> void:
	var prev_target := nav_agent.target_position
	nav_agent.target_position = source
	# Check that the source isn't too far away, e.g. a sound from another room
	if _current_path_shorter_than(STALKING_SOUND_LIMIT):
		# First detection switches to stalking, second switches to pursuit
		if state == State.STALKING:
			state = State.PURSUIT
		else:
			state = State.STALKING
	else:
		nav_agent.target_position = prev_target


func on_player_entered_grabbing_range(_body: Node3D) -> void:
	print_debug("GET GRABBED, IDIOT!")


func on_player_left_pursuit_range(_body: Node3D) -> void:
	state = State.STALKING


func on_stalking_timeout_timeout() -> void:
	state = State.LURKING


func on_stalking_idle_timer_timeout() -> void:
	pass  # Replace with function body.

#endregion