extends CharacterBody2D

## 小怪：在平台上左右巡逻，碰到玩家扣一颗心；
## 被玩家从上方踩到就死，并且把玩家弹起来。
## 走到平台边缘会自动掉头，所以不会掉下去。

@export var speed: float = 28.0
@export var damage: int = 1
## 被踩死时把玩家往上弹的速度
@export var stomp_bounce: float = -150.0
## 巡逻方向：-1 向左，1 向右
@export var start_direction: int = -1
## 掉头后的冷却时间：防止贴着墙时每帧都掉头、结果原地抖动
@export var turn_cooldown: float = 0.25

var direction: int = -1
var dead: bool = false

var _turn_timer: float = 0.0

@onready var sprite: Sprite2D = $Sprite
@onready var floor_probe: RayCast2D = $FloorProbe
@onready var touch_area: Area2D = $TouchArea


func _ready() -> void:
	add_to_group("enemy")
	direction = -1 if start_direction < 0 else 1
	_apply_direction()
	touch_area.body_entered.connect(_on_touch)


func _physics_process(delta: float) -> void:
	if dead:
		return

	if _turn_timer > 0.0:
		_turn_timer -= delta

	if not is_on_floor():
		velocity += get_gravity() * delta
	velocity.x = float(direction) * speed

	# 撞到墙 或 前方脚下没有地板 -> 掉头（带冷却，掉头后先走一段再说）
	if _turn_timer <= 0.0:
		if is_on_wall() or (is_on_floor() and not floor_probe.is_colliding()):
			direction = -direction
			_turn_timer = turn_cooldown
			_apply_direction()

	move_and_slide()


func _apply_direction() -> void:
	if sprite != null:
		sprite.flip_h = direction > 0
	if floor_probe != null:
		floor_probe.position.x = float(direction) * 6.0


func _on_touch(body: Node2D) -> void:
	if dead or not body.has_method("hurt"):
		return

	# 玩家从上往下踩到 -> 小怪死，玩家弹一下
	var p := body as CharacterBody2D
	if p != null and p.velocity.y > 0.0 and p.global_position.y < global_position.y - 3.0:
		p.velocity.y = stomp_bounce
		_die()
		return

	body.hurt(damage)


func _die() -> void:
	dead = true
	velocity = Vector2.ZERO
	touch_area.set_deferred("monitoring", false)
	set_deferred("collision_layer", 0)
	set_deferred("collision_mask", 0)

	# 被踩扁 + 淡出
	var tw := create_tween()
	tw.set_parallel(true)
	tw.tween_property(sprite, "scale", Vector2(1.35, 0.2), 0.12)
	tw.tween_property(sprite, "modulate:a", 0.0, 0.3)
	tw.chain().tween_callback(queue_free)