class_name Game
extends Node2D
## 游戏总装：世界构建、HUD、生命与游戏结束流程。
## 场景树全部由代码构建，入口场景只挂本脚本。

enum State { PLAYING, GAME_OVER }

const VIEW_SIZE := Vector2(540.0, 960.0)
const START_LIVES := 3
const BOMB_ICON := preload("res://assets/svg/bomb_icon.svg")
const BOSS_BAR_WIDTH := 260.0
const BOMB_DAMAGE := 30

var score := 0
var lives := START_LIVES
var state := State.PLAYING

var player: Player

var _hud_score: Label
var _lives_box: Node2D
var _overlay: CanvasLayer
var _final_score_label: Label
var _over_since_msec := 0
var _effects: Node2D
var _enemy_bullets: Node2D
var _enemies: Node2D
var _boss: Boss
var _boss_bar_bg: ColorRect
var _boss_bar_fill: ColorRect
var _warning: Label
var _shake_amp := 0.0
var _bombs_box: Node2D
var _flash_rect: ColorRect
var _flash_tween: Tween


func _ready() -> void:
	add_to_group("game")
	randomize()
	_build_world()
	_build_hud()
	_build_overlay()
	_update_lives()
	_update_score_label()


func _process(delta: float) -> void:
	if state == State.GAME_OVER:
		var accept := Input.is_action_just_pressed("ui_accept") or Input.is_action_just_pressed("fire")
		if accept and Time.get_ticks_msec() - _over_since_msec > 800:
			get_tree().change_scene_to_file("res://scenes/title.tscn")
			return

	_update_boss_bar()
	_update_shake(delta)


func _update_boss_bar() -> void:
	# 注意：已释放实例 == null 也为真，判存活必须用 is_instance_valid
	if not is_instance_valid(_boss):
		if _boss_bar_bg.visible:
			_boss_bar_bg.visible = false
			_boss_bar_fill.visible = false
		return
	var ratio := clampf(float(_boss.hp) / float(_boss.max_hp), 0.0, 1.0)
	_boss_bar_fill.size.x = BOSS_BAR_WIDTH * ratio


func _update_shake(delta: float) -> void:
	if _shake_amp > 0.2:
		_shake_amp = lerpf(_shake_amp, 0.0, 8.0 * delta)
		position = Vector2(randf_range(-1.0, 1.0), randf_range(-1.0, 1.0)) * _shake_amp
	elif _shake_amp != 0.0:
		_shake_amp = 0.0
		position = Vector2.ZERO


func _build_world() -> void:
	add_child(OceanScroll.new())

	var player_bullets := Node2D.new()
	player_bullets.name = "PlayerBullets"
	player_bullets.add_to_group("player_bullets")
	add_child(player_bullets)

	_enemy_bullets = Node2D.new()
	_enemy_bullets.name = "EnemyBullets"
	_enemy_bullets.add_to_group("enemy_bullets")
	add_child(_enemy_bullets)

	_enemies = Node2D.new()
	_enemies.name = "Enemies"
	_enemies.add_to_group("enemies")
	add_child(_enemies)

	var powerups := Node2D.new()
	powerups.name = "Powerups"
	powerups.add_to_group("powerups")
	add_child(powerups)

	player = Player.new()
	player.variant = GameSession.plane_variant as Player.Variant
	player.position = VIEW_SIZE * Vector2(0.5, 0.82)
	player.hit.connect(_on_player_hit)
	add_child(player)

	_effects = Node2D.new()
	_effects.name = "Effects"
	add_child(_effects)

	add_child(WaveSpawner.new())


func _build_hud() -> void:
	var layer := CanvasLayer.new()
	layer.layer = 10
	add_child(layer)

	_hud_score = Label.new()
	_hud_score.position = Vector2(16.0, 10.0)
	_hud_score.add_theme_font_size_override("font_size", 26)
	_hud_score.add_theme_color_override("font_color", Color.WHITE)
	_hud_score.add_theme_color_override("font_shadow_color", Color(0.0, 0.0, 0.0, 0.6))
	_hud_score.add_theme_constant_override("shadow_offset_x", 2)
	_hud_score.add_theme_constant_override("shadow_offset_y", 2)
	layer.add_child(_hud_score)

	_lives_box = Node2D.new()
	_lives_box.position = Vector2(520.0, 38.0)
	layer.add_child(_lives_box)

	# 炸弹计数（生命图标下方）
	_bombs_box = Node2D.new()
	_bombs_box.position = Vector2(520.0, 72.0)
	layer.add_child(_bombs_box)
	_update_bombs()

	# 炸弹白闪层（最顶层）
	var flash_layer := CanvasLayer.new()
	flash_layer.layer = 30
	add_child(flash_layer)
	_flash_rect = ColorRect.new()
	_flash_rect.color = Color.WHITE
	_flash_rect.set_anchors_preset(Control.PRESET_FULL_RECT)
	_flash_rect.modulate.a = 0.0
	flash_layer.add_child(_flash_rect)

	# Boss 血条（顶栏中央）
	_boss_bar_bg = ColorRect.new()
	_boss_bar_bg.position = Vector2(140.0, 54.0)
	_boss_bar_bg.size = Vector2(BOSS_BAR_WIDTH + 4.0, 14.0)
	_boss_bar_bg.color = Color(0.0, 0.0, 0.0, 0.65)
	_boss_bar_bg.visible = false
	layer.add_child(_boss_bar_bg)

	_boss_bar_fill = ColorRect.new()
	_boss_bar_fill.position = Vector2(142.0, 56.0)
	_boss_bar_fill.size = Vector2(BOSS_BAR_WIDTH, 10.0)
	_boss_bar_fill.color = Color(0.85, 0.2, 0.15)
	_boss_bar_fill.visible = false
	layer.add_child(_boss_bar_fill)

	# Boss 登场警告横幅
	_warning = Label.new()
	_warning.text = "WARNING!!"
	_warning.position = Vector2(0.0, 330.0)
	_warning.size = Vector2(540.0, 70.0)
	_warning.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
	_warning.add_theme_font_size_override("font_size", 56)
	_warning.add_theme_color_override("font_color", Color(1.0, 0.25, 0.2))
	_warning.add_theme_color_override("font_shadow_color", Color(0.0, 0.0, 0.0, 0.7))
	_warning.add_theme_constant_override("shadow_offset_x", 3)
	_warning.add_theme_constant_override("shadow_offset_y", 3)
	_warning.visible = false
	layer.add_child(_warning)


func _build_overlay() -> void:
	_overlay = CanvasLayer.new()
	_overlay.layer = 20

	var dim := ColorRect.new()
	dim.color = Color(0.0, 0.0, 0.0, 0.55)
	dim.set_anchors_preset(Control.PRESET_FULL_RECT)
	_overlay.add_child(dim)

	var center := CenterContainer.new()
	center.set_anchors_preset(Control.PRESET_FULL_RECT)
	_overlay.add_child(center)

	var vbox := VBoxContainer.new()
	vbox.add_theme_constant_override("separation", 18)
	vbox.alignment = BoxContainer.ALIGNMENT_CENTER
	center.add_child(vbox)

	var title := Label.new()
	title.text = "GAME OVER"
	title.add_theme_font_size_override("font_size", 52)
	title.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
	vbox.add_child(title)

	_final_score_label = Label.new()
	_final_score_label.add_theme_font_size_override("font_size", 30)
	_final_score_label.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
	vbox.add_child(_final_score_label)

	var hint := Label.new()
	hint.text = "回车 / 空格 重新开始"
	hint.add_theme_font_size_override("font_size", 22)
	hint.modulate = Color(0.8, 0.8, 0.8)
	hint.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
	vbox.add_child(hint)

	_overlay.visible = false
	add_child(_overlay)


func add_score(value: int) -> void:
	score += value
	_update_score_label()


func spawn_explosion(pos: Vector2, explosion_scale: float = 1.0) -> void:
	var explosion := Explosion.new()
	explosion.size = explosion_scale
	_effects.add_child(explosion)
	explosion.global_position = pos


## 生成关底 Boss 并显示血条
func spawn_boss(p_difficulty: float) -> Boss:
	var boss := Boss.new()
	boss.setup(p_difficulty)
	_enemies.add_child(boss)
	_boss = boss
	_boss_bar_bg.visible = true
	_boss_bar_fill.visible = true
	return boss


## Boss 登场前红色闪烁警告
func show_boss_warning() -> void:
	_warning.visible = true
	var tween := create_tween().set_loops(4)
	tween.tween_property(_warning, "modulate:a", 0.1, 0.22)
	tween.tween_property(_warning, "modulate:a", 1.0, 0.22)
	tween.finished.connect(func() -> void: _warning.visible = false)


## 屏幕震动（强度衰减）
func shake(amp: float) -> void:
	_shake_amp = maxf(_shake_amp, amp)


## 清除全场敌方弹幕
func clear_enemy_bullets() -> void:
	for bullet in _enemy_bullets.get_children():
		bullet.queue_free()


## 炸弹引爆：白闪 + 清弹 + 全场伤害 + 震屏（伤害数值由调用方计数）
func detonate_bomb() -> void:
	_update_bombs()
	if _flash_tween != null and _flash_tween.is_valid():
		_flash_tween.kill()
	_flash_rect.modulate.a = 0.85
	_flash_tween = create_tween()
	_flash_tween.tween_property(_flash_rect, "modulate:a", 0.0, 0.45) \
		.set_trans(Tween.TRANS_QUAD).set_ease(Tween.EASE_OUT)
	clear_enemy_bullets()
	for enemy in _enemies.get_children():
		if enemy is EnemyBase:
			(enemy as EnemyBase).apply_damage(BOMB_DAMAGE)
	shake(7.0)


## 炸弹 +1（上限 Player.BOMBS_MAX）
func add_bomb() -> void:
	if player != null and is_instance_valid(player):
		player.bombs = mini(player.bombs + 1, Player.BOMBS_MAX)
	_update_bombs()


## 拾取 B 道具：+1 炸弹并刷新 HUD
func notify_bomb_pickup() -> void:
	_update_bombs()


func _update_bombs() -> void:
	if _bombs_box == null:
		return
	for icon in _bombs_box.get_children():
		icon.queue_free()
	var count := player.bombs if player != null else 0
	for i in count:
		var icon := Sprite2D.new()
		icon.texture = BOMB_ICON
		icon.scale = Vector2.ONE * 0.8
		icon.position = Vector2(-22.0 * i, 0.0)
		_bombs_box.add_child(icon)


func _on_player_hit() -> void:
	if state != State.PLAYING or not player.active:
		return
	lives -= 1
	_update_lives()
	spawn_explosion(player.global_position, 1.6)
	clear_enemy_bullets()
	player.die()
	if lives <= 0:
		state = State.GAME_OVER
		_show_game_over()
	else:
		await get_tree().create_timer(0.9).timeout
		if state == State.PLAYING:
			player.respawn(VIEW_SIZE * Vector2(0.5, 0.82))


func _show_game_over() -> void:
	_final_score_label.text = "得分  " + str(score).pad_zeros(6)
	_overlay.visible = true
	_over_since_msec = Time.get_ticks_msec()


func _update_score_label() -> void:
	_hud_score.text = "SCORE " + str(score).pad_zeros(6)


func _update_lives() -> void:
	for icon in _lives_box.get_children():
		icon.queue_free()
	for i in maxi(lives - 1, 0):
		var icon := Sprite2D.new()
		icon.texture = Player.TEX
		icon.scale = Vector2.ONE * 0.42
		icon.position = Vector2(-36.0 * i, 0.0)
		_lives_box.add_child(icon)