extends Node
class_name RateLimiter
## 速率限制器
## 防止消息洪水攻击和垃圾消息

# 速率限制配置
var max_messages_per_window: int = 10
var time_window: float = 1.0  # 1秒窗口
var cleanup_interval: float = 60.0  # 1分钟清理间隔

# 客户端消息记录
var client_message_history: Dictionary = {}

# 清理定时器
var cleanup_timer: Timer

## 初始化速率限制器
func _ready():
	"""初始化速率限制器"""
	# 从配置获取参数
	max_messages_per_window = SecurityConfig.get_config("network_security", "max_message_rate", 10)
	time_window = SecurityConfig.get_config("network_security", "rate_limit_window", 1.0)
	
	# 设置清理定时器
	cleanup_timer = Timer.new()
	cleanup_timer.wait_time = cleanup_interval
	cleanup_timer.timeout.connect(_cleanup_old_records)
	cleanup_timer.autostart = true
	add_child(cleanup_timer)
	
	print("RateLimiter initialized - Max: %d msgs/%s sec" % [max_messages_per_window, time_window])

## 检查是否允许消息
func is_message_allowed(client_id: String) -> bool:
	"""
	检查客户端是否允许发送消息
	@param client_id: 客户端ID
	@return: 是否允许
	"""
	var current_time = Time.get_unix_time_from_system()
	
	# 获取或创建客户端记录
	if not client_message_history.has(client_id):
		client_message_history[client_id] = {
			"messages": [],
			"last_cleanup": current_time
		}
	
	var client_record = client_message_history[client_id]
	var messages = client_record.messages
	
	# 清理过期消息
	_cleanup_client_messages(client_id, current_time)
	
	# 检查是否超过限制
	if messages.size() >= max_messages_per_window:
		print("WARNING: Rate limit exceeded for client: " + client_id + " (" + str(messages.size()) + " messages)")
		return false
	
	# 记录新消息
	messages.append(current_time)
	return true

## 清理客户端的过期消息记录
func _cleanup_client_messages(client_id: String, current_time: float):
	"""
	清理客户端的过期消息记录
	@param client_id: 客户端ID
	@param current_time: 当前时间
	"""
	if not client_message_history.has(client_id):
		return
	
	var client_record = client_message_history[client_id]
	var messages = client_record.messages
	var cutoff_time = current_time - time_window
	
	# 移除过期消息
	var valid_messages = []
	for timestamp in messages:
		if timestamp > cutoff_time:
			valid_messages.append(timestamp)
	
	client_record.messages = valid_messages
	client_record.last_cleanup = current_time

## 清理所有过期记录
func _cleanup_old_records():
	"""清理所有客户端的过期记录"""
	var current_time = Time.get_unix_time_from_system()
	var cleaned_clients = 0
	var removed_clients = []
	
	for client_id in client_message_history:
		var client_record = client_message_history[client_id]
		
		# 如果客户端超过5分钟没有活动，移除记录
		if current_time - client_record.last_cleanup > 300.0:
			removed_clients.append(client_id)
		else:
			# 清理过期消息
			_cleanup_client_messages(client_id, current_time)
			cleaned_clients += 1
	
	# 移除不活跃的客户端记录
	for client_id in removed_clients:
		client_message_history.erase(client_id)
	
	if removed_clients.size() > 0:
		print("Rate limiter cleaned up %d inactive clients, %d active clients remain" % [removed_clients.size(), cleaned_clients])

## 重置客户端限制
func reset_client_limit(client_id: String):
	"""
	重置客户端的速率限制（用于特殊情况）
	@param client_id: 客户端ID
	"""
	if client_message_history.has(client_id):
		client_message_history[client_id].messages.clear()
		print("Rate limit reset for client: " + client_id)

## 获取客户端消息统计
func get_client_stats(client_id: String) -> Dictionary:
	"""
	获取客户端的消息统计
	@param client_id: 客户端ID
	@return: 统计信息
	"""
	if not client_message_history.has(client_id):
		return {
			"message_count": 0,
			"remaining_quota": max_messages_per_window,
			"window_reset_time": 0
		}
	
	var current_time = Time.get_unix_time_from_system()
	_cleanup_client_messages(client_id, current_time)
	
	var client_record = client_message_history[client_id]
	var message_count = client_record.messages.size()
	var remaining_quota = max(0, max_messages_per_window - message_count)
	
	# 计算窗口重置时间
	var oldest_message_time = 0.0
	if client_record.messages.size() > 0:
		oldest_message_time = client_record.messages[0]
	
	var window_reset_time = oldest_message_time + time_window
	
	return {
		"message_count": message_count,
		"remaining_quota": remaining_quota,
		"window_reset_time": window_reset_time,
		"current_time": current_time
	}

## 获取全局统计
func get_global_stats() -> Dictionary:
	"""
	获取全局速率限制统计
	@return: 全局统计信息
	"""
	var total_clients = client_message_history.size()
	var active_clients = 0
	var total_messages = 0
	var current_time = Time.get_unix_time_from_system()
	
	for client_id in client_message_history:
		var client_record = client_message_history[client_id]
		if current_time - client_record.last_cleanup < 60.0:  # 1分钟内活跃
			active_clients += 1
		total_messages += client_record.messages.size()
	
	return {
		"total_clients": total_clients,
		"active_clients": active_clients,
		"total_messages_in_window": total_messages,
		"max_rate": max_messages_per_window,
		"time_window": time_window
	}

## 设置速率限制参数
func set_rate_limit(max_messages: int, window_seconds: float):
	"""
	动态设置速率限制参数
	@param max_messages: 最大消息数
	@param window_seconds: 时间窗口（秒）
	"""
	max_messages_per_window = max_messages
	time_window = window_seconds
	
	print("Rate limit updated - Max: %d msgs/%s sec" % [max_messages, window_seconds])

## 检查是否为可疑活动
func is_suspicious_activity(client_id: String) -> bool:
	"""
	检查客户端是否有可疑活动
	@param client_id: 客户端ID
	@return: 是否可疑
	"""
	var stats = get_client_stats(client_id)
	
	# 如果消息数量接近限制，认为可疑
	if stats.message_count >= max_messages_per_window * 0.8:
		return true
	
	# 检查消息发送模式是否异常（过于规律可能是机器人）
	if client_message_history.has(client_id):
		var messages = client_message_history[client_id].messages
		if messages.size() >= 3:
			var intervals = []
			for i in range(1, messages.size()):
				intervals.append(messages[i] - messages[i-1])
			
			# 如果所有间隔都非常相似（差异小于0.1秒），可能是机器人
			if intervals.size() >= 2:
				var avg_interval = 0.0
				for interval in intervals:
					avg_interval += interval
				avg_interval /= intervals.size()
				
				var variance = 0.0
				for interval in intervals:
					variance += (interval - avg_interval) * (interval - avg_interval)
				variance /= intervals.size()
				
				if variance < 0.01:  # 方差很小，模式过于规律
					return true
	
	return false