extends CharacterBody3D

var rng = RandomNumberGenerator.new()
@export var target_location_xz = global_transform.origin * Vector3(1, 0, 1)
@export var location_xz = global_transform.origin * Vector3(1, 0, 1)
@export var target_direction_xz = (transform.basis * Vector3(1, 0, 1)).normalized()
@export var direction_xz = (transform.basis * Vector3(1, 0, 1)).normalized()
var task = "idle"

# Percentage chances of the character performing certain actions while idle.
@export var walk_chance = 0.1
@export var spin_chance = 0.2

@export var walk_speed = 0.5

# Rate at which character corrects their direction after going off course (percentage).
@export var dir_correction_rate = 0.95

# Margin of accuracy to which the character will correct their direction when off course (radians).
@export var dir_accuracy = deg_to_rad(0.1)

# Get the gravity from the project settings to be synced with RigidBody nodes.
var gravity = ProjectSettings.get_setting("physics/3d/default_gravity")

# Called when the node enters the scene tree for the first time.
func _ready():
	pass


# Called every frame. 'delta' is the elapsed time since the previous frame.
func _process(delta):
	location_xz = global_transform.origin * Vector3(1, 0, 1)
	direction_xz = (transform.basis * Vector3(1, 0, 1)).normalized()
	
	match task:
		"idle":
			task = rng.randf_range(0, 100)
			
			# 3% chance to walk somewhere.
			if task <= walk_chance:
				task = "walk"
				target_location_xz = global_transform.origin * Vector3(1, 0, 1) + (direction_xz * 16)
			# 6% chance to rotate.
			elif task > walk_chance and task <= (walk_chance + spin_chance):
				task = "spin"
				var rotation_angle = rng.randf_range(-2*PI, 2*PI)
				var rotation_vector = Vector3(cos(rotation_angle), 0, sin(rotation_angle))
				target_direction_xz = direction_xz + rotation_vector
			# 90% chance to idle.
			elif task > (spin_chance + walk_chance):
				task = "idle"
		
		"walk":
			# Get the direction to the target in z-x plane.
			target_direction_xz = (location_xz.direction_to(target_location_xz) * Vector3(1, 0, 1)).normalized()
			
			# Continue to correct direction to within a margin of dir_accuracy degrees.
			if direction_xz.angle_to(target_direction_xz) >= dir_accuracy:
				# Rotate towards destination at specified percentage rate. 
				rotate_y(direction_xz.angle_to(target_direction_xz) * dir_correction_rate)
				
			if location_xz.distance_to(target_location_xz) <= (Vector2(direction_xz.x, direction_xz.z) * walk_speed).length():
				target_direction_xz = direction_xz
				target_location_xz = location_xz
				task = "idle"
		
		"spin":
			task = "idle"
						
		

func _physics_process(delta):
	# Add the gravity.
	if not is_on_floor():
		velocity.y -= gravity * delta
		
	# Walk to target location.
	if location_xz.distance_to(target_location_xz) > (Vector2(direction_xz.x, direction_xz.z) * walk_speed).length():
		velocity.x = direction_xz.x * walk_speed
		velocity.z = direction_xz.z * walk_speed
	
	move_and_slide()