extends CharacterBody3D

const CHASE_SPEED := 3.5
const RETURN_SPEED := 2.5
const GRAVITY := -15.0

const ATTACK_COOLDOWN := 1.5
const ATTACK_DIST := 3.0
const ATTACK_WINDUP := 0.75

var target: Node3D = null
var spawn_position := Vector3()
var chasing := true
var _attack_cooldown := 0.0
var _windup_timer := 0.0
var _is_flashing := false


func set_target(node: Node3D) -> void:
	target = node


func _physics_process(delta: float) -> void:
	if not target:
		return

	var goal_pos: Vector3

	if chasing:
		goal_pos = target.global_position
	elif not chasing:
		goal_pos = spawn_position
	else:
		goal_pos = global_position

	var to_goal := goal_pos - global_position
	to_goal.y = 0.0
	var distance := to_goal.length()

	if distance < 0.5:
		velocity.x = 0.0
		velocity.z = 0.0
	else:
		var direction := to_goal.normalized()
		var speed := CHASE_SPEED if chasing else RETURN_SPEED
		velocity.x = direction.x * speed
		velocity.z = direction.z * speed
		var target_angle := atan2(direction.x, direction.z)
		var current_angle := rotation.y
		var diff := target_angle - current_angle
		while diff > PI:
			diff -= TAU
		while diff < -PI:
			diff += TAU
		rotation.y += diff * clampf(10.0 * delta, 0.0, 1.0)

	if not is_on_floor():
		velocity.y += GRAVITY * delta

	_attack_cooldown = maxf(0.0, _attack_cooldown - delta)

	if chasing and distance < ATTACK_DIST and _attack_cooldown <= 0.0:
		velocity.x = 0.0
		velocity.z = 0.0
		_face_player(delta)
		_windup_timer += delta
		if _windup_timer >= ATTACK_WINDUP:
			_windup_timer = 0.0
			var to_player := target.global_position - global_position
			to_player.y = 0.0
			if to_player.length() < ATTACK_DIST:
				target.take_hit()
			_attack_cooldown = ATTACK_COOLDOWN
	else:
		_windup_timer = 0.0

	move_and_slide()


func _face_player(delta: float) -> void:
	var direction := (target.global_position - global_position)
	direction.y = 0.0
	direction = direction.normalized()
	var target_angle := atan2(direction.x, direction.z)
	var current_angle := rotation.y
	var diff := target_angle - current_angle
	while diff > PI:
		diff -= TAU
	while diff < -PI:
		diff += TAU
	rotation.y += diff * clampf(10.0 * delta, 0.0, 1.0)


func take_hit() -> void:
	if _is_flashing:
		return
	_is_flashing = true
	_flash_meshes(Color.WHITE, Color.WHITE, 0.15)


func _flash_meshes(flash_color: Color, emissive_color: Color, duration: float) -> void:
	var flash_mat := StandardMaterial3D.new()
	flash_mat.albedo_color = flash_color
	flash_mat.emission = emissive_color
	flash_mat.emission_energy = 2.0
	for child in get_children():
		if child is MeshInstance3D:
			var old: Material = child.material_override
			child.material_override = flash_mat
			await get_tree().create_timer(duration).timeout
			child.material_override = old
	_is_flashing = false