extends Area2D

## 激光。两种模式：
##  - always_on = true（默认）：**固定障碍** —— 一直亮着，碰到就扣血，只能绕开或用钥匙传送穿过去
##  - always_on = false：循环「蓄力闪烁 -> 发射 -> 熄灭」，需要卡时间通过
## 光束从自己的原点沿 +X 方向伸出，想改朝向就转节点本身。

enum State { WAIT, WARMUP, FIRING }

## 固定障碍模式（一直亮着）
@export var always_on: bool = true
@export var length: float = 90.0
@export var thickness: float = 6.0
@export var damage: int = 1
## 蓄力（闪烁警告）时长，只有循环模式用
@export var warmup: float = 0.8
## 发射持续时长，只有循环模式用
@export var fire_time: float = 0.35
## 两次发射之间的间隔，只有循环模式用
@export var cooldown: float = 1.8
## 开场后第一次发射前的延迟，只有循环模式用
@export var start_delay: float = 1.0
@export var laser_color: Color = Color(1.0, 0.25, 0.25)
@export var warn_color: Color = Color(1.0, 0.8, 0.4)

var _state: int = State.WAIT
var _timer: float = 0.0
var _first: bool = true
var _beam: Polygon2D = null


func _ready() -> void:
	add_to_group("hazard")
	_beam = get_node_or_null("Beam") as Polygon2D
	var half := thickness * 0.5
	if _beam != null:
		_beam.polygon = PackedVector2Array([
			Vector2(0.0, -half), Vector2(length, -half),
			Vector2(length, half), Vector2(0.0, half)])
		_beam.color = laser_color
		_beam.visible = always_on
	var hit := get_node_or_null("HitBox") as CollisionShape2D
	if hit != null:
		var rect := RectangleShape2D.new()
		rect.size = Vector2(length, thickness)
		hit.shape = rect
		hit.position = Vector2(length * 0.5, 0.0)


func _physics_process(delta: float) -> void:
	if always_on:
		if _beam != null:
			_beam.visible = true
			_beam.color = laser_color
		_hurt_overlaps()
		return

	_timer += delta
	match _state:
		State.WAIT:
			var wait: float = start_delay if _first else cooldown
			if _timer >= wait:
				_first = false
				_state = State.WARMUP
				_timer = 0.0
		State.WARMUP:
			if _beam != null:
				_beam.color = warn_color
				_beam.visible = fmod(_timer, 0.16) < 0.08
			if _timer >= warmup:
				_state = State.FIRING
				_timer = 0.0
				if _beam != null:
					_beam.color = laser_color
					_beam.visible = true
		State.FIRING:
			_hurt_overlaps()
			if _timer >= fire_time:
				_state = State.WAIT
				_timer = 0.0
				if _beam != null:
					_beam.visible = false


## 每帧检查压在光柱里的东西（不能只靠 body_entered，
## 因为玩家可能本来就在光柱里，那样不会触发 entered）
func _hurt_overlaps() -> void:
	for body in get_overlapping_bodies():
		if body.has_method("hurt"):
			body.hurt(damage)