extends Node

# ============================================================================
# WebSocketManager.gd - WebSocket 连接生命周期管理
# ============================================================================
# 管理 WebSocket 连接状态、自动重连和错误恢复
#
# 核心职责:
# - 连接状态管理（断开、连接中、已连接、重连中）
# - 自动重连机制（指数退避）
# - 连接错误恢复
# - Socket.IO 客户端封装
#
# 使用方式:
#   WebSocketManager.connect_to_game_server()
#   WebSocketManager.connection_state_changed.connect(_on_state_changed)
#
# 注意事项:
# - 作为自动加载单例，全局可访问
# - 自动处理连接断开和重连
# - 通过信号通知连接状态变化
# ============================================================================

class_name WebSocketManager

# ============================================================================
# 信号定义
# ============================================================================

# 连接状态变化信号
# 参数:
#   new_state: ConnectionState - 新的连接状态
signal connection_state_changed(new_state: ConnectionState)

# 连接丢失信号
signal connection_lost()

# 重连成功信号
signal reconnection_succeeded()

# 重连失败信号
# 参数:
#   attempt: int - 当前重连尝试次数
#   max_attempts: int - 最大重连次数
signal reconnection_failed(attempt: int, max_attempts: int)

# ============================================================================
# 枚举定义
# ============================================================================

# 连接状态枚举
enum ConnectionState {
	DISCONNECTED,   # 未连接
	CONNECTING,     # 连接中
	CONNECTED,      # 已连接
	RECONNECTING,   # 重连中
	ERROR           # 错误状态
}

# ============================================================================
# 常量定义
# ============================================================================

# WebSocket 服务器 URL
const WEBSOCKET_URL: String = "wss://whaletownend.xinghangee.icu/game"

# 默认最大重连次数
const DEFAULT_MAX_RECONNECT_ATTEMPTS: int = 5

# 默认重连基础延迟（秒）
const DEFAULT_RECONNECT_BASE_DELAY: float = 3.0

# 最大重连延迟（秒）
const MAX_RECONNECT_DELAY: float = 30.0

# ============================================================================
# 成员变量
# ============================================================================

# Socket.IO 客户端
var _socket_client: SocketIOClient

# 当前连接状态
var _connection_state: ConnectionState = ConnectionState.DISCONNECTED

# 自动重连启用标志
var _auto_reconnect_enabled: bool = true

# 最大重连次数
var _max_reconnect_attempts: int = DEFAULT_MAX_RECONNECT_ATTEMPTS

# 重连基础延迟
var _reconnect_base_delay: float = DEFAULT_RECONNECT_BASE_DELAY

# 当前重连尝试次数
var _reconnect_attempt: int = 0

# 重连定时器
var _reconnect_timer: Timer = Timer.new()

# 是否为正常关闭（非异常断开）
var _clean_close: bool = true

# ============================================================================
# 生命周期方法
# ============================================================================

# 初始化
func _ready() -> void:
	print("WebSocketManager 初始化完成")

	# 创建 Socket.IO 客户端
	_socket_client = SocketIOClient.new()
	add_child(_socket_client)

	# 连接信号
	_socket_client.connected.connect(_on_socket_connected)
	_socket_client.disconnected.connect(_on_socket_disconnected)
	_socket_client.error_occurred.connect(_on_socket_error)

	# 设置重连定时器
	_setup_reconnect_timer()

# 清理
func _exit_tree() -> void:
	if is_instance_valid(_reconnect_timer):
		_reconnect_timer.stop()
		_reconnect_timer.queue_free()

# ============================================================================
# 公共 API - 连接管理
# ============================================================================

# 连接到游戏服务器
func connect_to_game_server() -> void:
	if _connection_state == ConnectionState.CONNECTED or _connection_state == ConnectionState.CONNECTING:
		push_warning("已经在连接或已连接状态")
		return

	print("=== WebSocketManager 开始连接 ===")
	_set_connection_state(ConnectionState.CONNECTING)
	_clean_close = true
	_reconnect_attempt = 0

	_socket_client.connect_to_server(WEBSOCKET_URL)

# 断开 WebSocket 连接
func disconnect_websocket() -> void:
	print("=== WebSocketManager 断开连接 ===")
	_clean_close = true

	# 停止重连定时器
	_reconnect_timer.stop()

	# 断开客户端
	_socket_client.disconnect_from_server()
	_set_connection_state(ConnectionState.DISCONNECTED)

# 检查 WebSocket 是否已连接
#
# 返回值:
#   bool - WebSocket 是否已连接
func is_websocket_connected() -> bool:
	return _connection_state == ConnectionState.CONNECTED

# 获取当前连接状态
#
# 返回值:
#   ConnectionState - 当前连接状态
func get_connection_state() -> ConnectionState:
	return _connection_state

# ============================================================================
# 公共 API - 自动重连
# ============================================================================

# 启用/禁用自动重连
#
# 参数:
#   enabled: bool - 是否启用自动重连
#   max_attempts: int - 最大重连次数（默认 5）
#   base_delay: float - 基础重连延迟，秒（默认 3.0）
#
# 使用示例:
#   WebSocketManager.enable_auto_reconnect(true, 5, 3.0)
func enable_auto_reconnect(enabled: bool, max_attempts: int = DEFAULT_MAX_RECONNECT_ATTEMPTS, base_delay: float = DEFAULT_RECONNECT_BASE_DELAY) -> void:
	_auto_reconnect_enabled = enabled
	_max_reconnect_attempts = max_attempts
	_reconnect_base_delay = base_delay

	print("自动重连: ", "启用" if enabled else "禁用")
	print("最大重连次数: ", _max_reconnect_attempts)
	print("基础重连延迟: ", _reconnect_base_delay, " 秒")

# 获取 Socket.IO 客户端
#
# 返回值:
#   SocketIOClient - Socket.IO 客户端实例
#
# 使用示例:
#   var socket = WebSocketManager.get_socket_client()
#   socket.emit("chat", {"t": "chat", "content": "Hello"})
func get_socket_client() -> SocketIOClient:
	return _socket_client

# ============================================================================
# 内部方法 - 连接状态管理
# ============================================================================

# 设置连接状态
func _set_connection_state(new_state: ConnectionState) -> void:
	if _connection_state == new_state:
		return

	_connection_state = new_state
	print("📡 连接状态变更: ", ConnectionState.keys()[new_state])

	# 发射信号
	connection_state_changed.emit(new_state)

# ============================================================================
# 内部方法 - Socket 事件处理
# ============================================================================

# Socket 连接成功处理
func _on_socket_connected() -> void:
	print("✅ WebSocketManager: Socket 连接成功")

	# 如果是重连，发射重连成功信号
	if _connection_state == ConnectionState.RECONNECTING:
		_reconnect_attempt = 0
		reconnection_succeeded.emit()
		print("🔄 重连成功")

	_set_connection_state(ConnectionState.CONNECTED)

# Socket 连接断开处理
func _on_socket_disconnected(clean_close: bool) -> void:
	print("🔌 WebSocketManager: Socket 连接断开")
	print("   正常关闭: ", clean_close)

	_clean_close = clean_close

	# 如果是异常断开且启用了自动重连
	if not clean_close and _auto_reconnect_enabled:
		connection_lost.emit()
		_attempt_reconnect()
	else:
		_set_connection_state(ConnectionState.DISCONNECTED)

# Socket 错误处理
func _on_socket_error(error: String) -> void:
	print("❌ WebSocketManager: Socket 错误 - ", error)
	_set_connection_state(ConnectionState.ERROR)

# ============================================================================
# 内部方法 - 重连机制
# ============================================================================

# 设置重连定时器
func _setup_reconnect_timer() -> void:
	_reconnect_timer = Timer.new()
	_reconnect_timer.one_shot = true
	_reconnect_timer.autostart = false
	add_child(_reconnect_timer)

	_reconnect_timer.timeout.connect(_on_reconnect_timeout)

# 尝试重连
func _attempt_reconnect() -> void:
	# 检查是否超过最大重连次数
	if _reconnect_attempt >= _max_reconnect_attempts:
		print("❌ 达到最大重连次数 (", _max_reconnect_attempts, ")，停止重连")
		reconnection_failed.emit(_reconnect_attempt, _max_reconnect_attempts)
		_set_connection_state(ConnectionState.ERROR)
		return

	_reconnect_attempt += 1
	_set_connection_state(ConnectionState.RECONNECTING)

	# 计算重连延迟（指数退避）
	var delay := _calculate_reconnect_delay()
	print("🔄 尝试重连 (", _reconnect_attempt, "/", _max_reconnect_attempts, ")")
	print("   延迟: ", delay, " 秒")

	# 启动重连定时器
	_reconnect_timer.start(delay)

# 计算重连延迟（指数退避）
func _calculate_reconnect_delay() -> float:
	# 指数退避: base_delay * 2^(attempt-1)
	var delay: float = _reconnect_base_delay * pow(2.0, _reconnect_attempt - 1)

	# 限制最大延迟
	return min(delay, MAX_RECONNECT_DELAY)

# 重连定时器超时处理
func _on_reconnect_timeout() -> void:
	print("⏰ 重连定时器超时，开始重连...")
	_socket_client.connect_to_server(WEBSOCKET_URL)

# ============================================================================
# 工具方法
# ============================================================================

# 获取连接状态描述
#
# 返回值:
#   String - 连接状态描述
func get_state_description() -> String:
	match _connection_state:
		ConnectionState.DISCONNECTED:
			return "未连接"
		ConnectionState.CONNECTING:
			return "连接中"
		ConnectionState.CONNECTED:
			return "已连接"
		ConnectionState.RECONNECTING:
			return "重连中 (%d/%d)" % [_reconnect_attempt, _max_reconnect_attempts]
		ConnectionState.ERROR:
			return "错误"
		_:
			return "未知状态"

# 获取重连信息
#
# 返回值:
#   Dictionary - 重连信息 {enabled, attempt, max_attempts, delay}
func get_reconnect_info() -> Dictionary:
	return {
		"enabled": _auto_reconnect_enabled,
		"attempt": _reconnect_attempt,
		"max_attempts": _max_reconnect_attempts,
		"next_delay": _calculate_reconnect_delay() if _connection_state == ConnectionState.RECONNECTING else 0.0
	}