import { OnModuleInit, OnModuleDestroy } from '@nestjs/common';
import { DataSource } from 'typeorm';
import { Observable } from 'rxjs';
export interface ConnectionPoolMetrics {
    totalConnections: number;
    activeConnections: number;
    idleConnections: number;
    waitingConnections: number;
    acquiredConnections: number;
    releasedConnections: number;
    createdConnections: number;
    destroyedConnections: number;
    poolSize: number;
    maxConnections: number;
    minConnections: number;
    connectionTimeouts: number;
    connectionErrors: number;
    averageAcquireTime: number;
    averageConnectionLifetime: number;
    healthScore: number;
    lastUpdate: Date;
}
export interface ConnectionEvent {
    type: 'acquire' | 'release' | 'create' | 'destroy' | 'timeout' | 'error';
    timestamp: Date;
    connectionId?: string;
    duration?: number;
    error?: string;
    poolState: {
        active: number;
        idle: number;
        waiting: number;
    };
}
export interface ConnectionPoolAlert {
    type: 'high_usage' | 'connection_timeout' | 'connection_error' | 'pool_exhausted' | 'connection_leak';
    severity: 'low' | 'medium' | 'high' | 'critical';
    message: string;
    timestamp: Date;
    metrics: Partial<ConnectionPoolMetrics>;
    recommendation: string;
}
export declare class ConnectionPoolMonitorService implements OnModuleInit, OnModuleDestroy {
    private readonly dataSource;
    private readonly logger;
    private readonly destroy$;
    private readonly metricsSubject;
    private readonly eventsSubject;
    private readonly alertsSubject;
    private connectionEvents;
    private readonly maxEventHistory;
    private readonly monitoringInterval;
    private acquireTimestamps;
    private connectionCreationTimes;
    private currentMetrics;
    private alertThresholds;
    constructor(dataSource: DataSource);
    onModuleInit(): Promise<void>;
    onModuleDestroy(): Promise<void>;
    private initializeMetrics;
    private setupMonitoring;
    private setupPoolEventListeners;
    private setupPostgresPoolListeners;
    private setupMySQLPoolListeners;
    private getCurrentPoolState;
    private updatePoolConfiguration;
    private startPeriodicMonitoring;
    private collectMetrics;
    private calculateAverageAcquireTime;
    private calculateAverageConnectionLifetime;
    private calculateHealthScore;
    private updateCountersFromEvents;
    private checkForAlerts;
    private recordEvent;
    private generateConnectionId;
    getMetrics(): ConnectionPoolMetrics;
    getMetricsStream(): Observable<ConnectionPoolMetrics>;
    getEventStream(): Observable<ConnectionEvent>;
    getAlertStream(): Observable<ConnectionPoolAlert>;
    getRecentEvents(limit?: number): ConnectionEvent[];
    getConnectionPoolHealth(): {
        score: number;
        status: 'healthy' | 'warning' | 'critical';
        issues: string[];
        recommendations: string[];
    };
    resetMetrics(): void;
}