/**
 * Log level for security events
 */
export declare enum SecurityLogLevel {
    INFO = "info",
    WARN = "warn",
    ERROR = "error",
    CRITICAL = "critical"
}
/**
 * Security event types for categorization
 */
export declare enum SecurityEventType {
    AUTHENTICATION = "authentication",
    ACCESS_CONTROL = "access_control",
    EMAIL_VALIDATION = "email_validation",
    EMAIL_PROCESSING = "email_processing",
    EMAIL_FORWARDING = "email_forwarding",
    EMAIL_DELIVERY = "email_delivery",
    DKIM = "dkim",
    SPF = "spf",
    DMARC = "dmarc",
    RATE_LIMIT = "rate_limit",
    RATE_LIMITING = "rate_limiting",
    SPAM = "spam",
    MALWARE = "malware",
    CONNECTION = "connection",
    DATA_EXPOSURE = "data_exposure",
    CONFIGURATION = "configuration",
    IP_REPUTATION = "ip_reputation",
    REJECTED_CONNECTION = "rejected_connection"
}
/**
 * Security event interface
 */
export interface ISecurityEvent {
    timestamp: number;
    level: SecurityLogLevel;
    type: SecurityEventType;
    message: string;
    details?: any;
    ipAddress?: string;
    userId?: string;
    sessionId?: string;
    emailId?: string;
    domain?: string;
    action?: string;
    result?: string;
    success?: boolean;
}
/**
 * Security logger for enhanced security monitoring
 */
export declare class SecurityLogger {
    private static instance;
    private securityEvents;
    private maxEventHistory;
    private enableNotifications;
    private constructor();
    /**
     * Get singleton instance
     */
    static getInstance(options?: {
        maxEventHistory?: number;
        enableNotifications?: boolean;
    }): SecurityLogger;
    /**
     * Reset the singleton instance (for shutdown/testing)
     */
    static resetInstance(): void;
    /**
     * Log a security event
     * @param event The security event to log
     */
    logEvent(event: Omit<ISecurityEvent, 'timestamp'>): void;
    /**
     * Get recent security events
     * @param limit Maximum number of events to return
     * @param filter Filter for specific event types
     * @returns Recent security events
     */
    getRecentEvents(limit?: number, filter?: {
        level?: SecurityLogLevel;
        type?: SecurityEventType;
        fromTimestamp?: number;
        toTimestamp?: number;
    }): ISecurityEvent[];
    /**
     * Get events by security level
     * @param level The security level to filter by
     * @param limit Maximum number of events to return
     * @returns Security events matching the level
     */
    getEventsByLevel(level: SecurityLogLevel, limit?: number): ISecurityEvent[];
    /**
     * Get events by security type
     * @param type The event type to filter by
     * @param limit Maximum number of events to return
     * @returns Security events matching the type
     */
    getEventsByType(type: SecurityEventType, limit?: number): ISecurityEvent[];
    /**
     * Get security events for a specific IP address
     * @param ipAddress The IP address to filter by
     * @param limit Maximum number of events to return
     * @returns Security events for the IP address
     */
    getEventsByIP(ipAddress: string, limit?: number): ISecurityEvent[];
    /**
     * Get security events for a specific domain
     * @param domain The domain to filter by
     * @param limit Maximum number of events to return
     * @returns Security events for the domain
     */
    getEventsByDomain(domain: string, limit?: number): ISecurityEvent[];
    /**
     * Send a notification for critical security events
     * @param event The security event to notify about
     * @private
     */
    private sendNotification;
    /**
     * Clear event history
     */
    clearEvents(): void;
    /**
     * Get statistical summary of security events
     * @param timeWindow Optional time window in milliseconds
     * @returns Summary of security events
     */
    getEventsSummary(timeWindow?: number): {
        total: number;
        byLevel: Record<SecurityLogLevel, number>;
        byType: Record<SecurityEventType, number>;
        topIPs: Array<{
            ip: string;
            count: number;
        }>;
        topDomains: Array<{
            domain: string;
            count: number;
        }>;
    };
}
