extends CharacterBody2D
## 球：未发射时停在挡板上，空格发射后在场地内反弹。
##
## 反弹规则：
## - 撞墙/砖块：镜面反射（用 collision.get_normal()）
## - 撞挡板：按击中挡板的横向偏移换算反弹角度——挡板中心=竖直反弹，
##   越靠边缘反弹角越大（打砖块手感的核心）。
## - 球速随击砖次数缓慢上升，到 max_speed 封顶。

signal lost                           ## 球出界
signal brick_hit(brick)               ## 命中砖块（用于计连击/提速）

@export var speed: float = 400.0            ## 初始球速
@export var max_speed: float = 700.0        ## 球速上限
@export var speed_gain_per_hit: float = 4.0 ## 每击碎一砖后提速
@export var spawn_offset_y: float = -24.0   ## 球相对挡板的垂直偏移
@export var launch_angle_deg: float = 60.0  ## 初始发射角度
@export var max_bounce_angle_deg: float = 75.0  ## 挡板最大反弹角（中心绝对值）

@onready var _paddle: CharacterBody2D = get_parent().get_node("Paddle")

var _launched: bool = false
var _current_speed: float = 0.0

func _ready() -> void:
	_current_speed = speed
	velocity = Vector2.ZERO

func _physics_process(_delta: float) -> void:
	if not _launched:
		# 跟随挡板
		position.x = _paddle.position.x
		position.y = _paddle.position.y + spawn_offset_y
		if Input.is_key_pressed(KEY_SPACE):
			_launch()
		return

	# 已发射：每帧移动并检测碰撞
	var motion: Vector2 = velocity * _delta
	var collision: KinematicCollision2D = move_and_collide(motion)
	if collision:
		var body := collision.get_collider()
		# 命中挡板：按击中位置算反弹角度
		if body == _paddle:
			_bounce_off_paddle(collision)
		else:
			# 撞墙/砖块：镜面反射
			velocity = velocity.bounce(collision.get_normal())
			velocity.x += randf_range(-5.0, 5.0)
		# 命中砖块：转给 main 并提速
		if body and body.is_in_group("bricks"):
			brick_hit.emit(body)
			_current_speed = min(_current_speed + speed_gain_per_hit, max_speed)
			velocity = velocity.normalized() * _current_speed

func _bounce_off_paddle(collision: KinematicCollision2D) -> void:
	# 球相对挡板中心的横向偏移，归一化到 [-1, 1]
	# 挡板加宽时，半宽从 paddle 实时读
	var half_paddle: float = _paddle.get_half_width() if _paddle.has_method("get_half_width") else 48.0
	var offset: float = clamp(
		(position.x - _paddle.position.x) / half_paddle, -1.0, 1.0
	)
	# 偏移 → 反弹角（0 = 竖直，max_bounce_angle_deg = 边缘）
	var angle_rad: float = deg_to_rad(offset * max_bounce_angle_deg)
	# 球只能向上飞（-Y 方向）
	velocity = Vector2(sin(angle_rad), -cos(angle_rad)) * _current_speed

func _launch() -> void:
	_launched = true
	var rad: float = deg_to_rad(launch_angle_deg)
	var dir_x: float = [-1.0, 1.0][randi() % 2]
	velocity = Vector2(cos(rad) * dir_x, -sin(rad)) * _current_speed

func reset_to_paddle() -> void:
	_launched = false
	_current_speed = speed
	velocity = Vector2.ZERO
	position.x = _paddle.position.x
	position.y = _paddle.position.y + spawn_offset_y