/**
 * SMTP Connection Manager
 * Responsible for managing socket connections to the SMTP server
 */
import * as plugins from '../../../plugins.js';
import type { IConnectionManager, ISmtpServer } from './interfaces.js';
/**
 * Manager for SMTP connections
 * Handles connection setup, event listeners, and lifecycle management
 * Provides resource management, connection tracking, and monitoring
 */
export declare class ConnectionManager implements IConnectionManager {
    /**
     * Reference to the SMTP server instance
     */
    private smtpServer;
    /**
     * Set of active socket connections
     */
    private activeConnections;
    /**
     * Connection tracking for resource management
     */
    private connectionStats;
    /**
     * Per-IP connection tracking for rate limiting
     */
    private ipConnections;
    /**
     * Resource monitoring interval
     */
    private resourceCheckInterval;
    /**
     * Track cleanup timers so we can clear them
     */
    private cleanupTimers;
    /**
     * SMTP server options with enhanced resource controls
     */
    private options;
    /**
     * Creates a new connection manager with enhanced resource management
     * @param smtpServer - SMTP server instance
     */
    constructor(smtpServer: ISmtpServer);
    /**
     * Start resource monitoring interval to check resource usage
     */
    private startResourceMonitoring;
    /**
     * Monitor resource usage and log statistics
     */
    private monitorResourceUsage;
    /**
     * Clean up expired IP rate limits and perform additional resource monitoring
     */
    private cleanupIpRateLimits;
    /**
     * Validate and repair resource tracking to prevent leaks
     */
    private validateResourceTracking;
    /**
     * Handle a new connection with resource management
     * @param socket - Client socket
     */
    handleNewConnection(socket: plugins.net.Socket): Promise<void>;
    /**
     * Check if an IP has exceeded the rate limit
     * @param ip - Client IP address
     * @returns True if rate limited
     */
    private isIPRateLimited;
    /**
     * Track a new connection from an IP
     * @param ip - Client IP address
     */
    private trackIPConnection;
    /**
     * Check if an IP has reached its connection limit
     * @param ip - Client IP address
     * @returns True if limit reached
     */
    private hasReachedIPConnectionLimit;
    /**
     * Handle a new secure TLS connection with resource management
     * @param socket - Client TLS socket
     */
    handleNewSecureConnection(socket: plugins.tls.TLSSocket): Promise<void>;
    /**
     * Set up event handlers for a socket with enhanced resource management
     * @param socket - Client socket
     */
    setupSocketEventHandlers(socket: plugins.net.Socket | plugins.tls.TLSSocket): void;
    /**
     * Get the current connection count
     * @returns Number of active connections
     */
    getConnectionCount(): number;
    /**
     * Check if the server has reached the maximum number of connections
     * @returns True if max connections reached
     */
    hasReachedMaxConnections(): boolean;
    /**
     * Close all active connections
     */
    closeAllConnections(): void;
    /**
     * Handle socket close event
     * @param socket - Client socket
     * @param hadError - Whether the socket was closed due to error
     */
    private handleSocketClose;
    /**
     * Handle socket error event
     * @param socket - Client socket
     * @param error - Error object
     */
    private handleSocketError;
    /**
     * Handle socket timeout event
     * @param socket - Client socket
     */
    private handleSocketTimeout;
    /**
     * Reject a connection
     * @param socket - Client socket
     * @param reason - Reason for rejection
     */
    private rejectConnection;
    /**
     * Send greeting message
     * @param socket - Client socket
     */
    private sendGreeting;
    /**
     * Send service closing notification
     * @param socket - Client socket
     */
    private sendServiceClosing;
    /**
     * Send response to client
     * @param socket - Client socket
     * @param response - Response to send
     */
    private sendResponse;
    /**
     * Handle a new connection (interface requirement)
     */
    handleConnection(socket: plugins.net.Socket | plugins.tls.TLSSocket, secure: boolean): Promise<void>;
    /**
     * Check if accepting new connections (interface requirement)
     */
    canAcceptConnection(): boolean;
    /**
     * Clean up resources
     */
    destroy(): void;
}