import { EventEmitter } from 'events';
import type { ILogObj } from 'tslog';
import { Logger } from 'tslog';
import type { IConnectionManager } from './IConnectionManager.js';
/**
 * Abstract base class for managing a message transport connection.
 *
 * Implementations are responsible for establishing, maintaining, and closing
 * connections to a specific transport backend (e.g. RabbitMQ, Kafka).
 *
 * Emits:
 * - `connected` when a connection is established (with the connection object as argument)
 * - `disconnected` when the connection is lost
 * - `error` on connection errors
 *
 * @template TConnection The transport-specific connection type returned by {@link connect}.
 */
export declare abstract class AbstractConnectionManager<TConnection = unknown> extends EventEmitter implements IConnectionManager {
    protected _logger: Logger<ILogObj>;
    state: string;
    constructor(logger?: Logger<ILogObj>);
    /**
     * Establishes a connection to the transport backend.
     * Implementations should handle in-progress connection attempts and
     * return the existing connection if already connected.
     */
    abstract connect(): Promise<TConnection>;
    /**
     * Gracefully closes the connection.
     */
    abstract close(): Promise<void>;
    /**
     * Returns true if there is an active connection.
     */
    abstract isConnected(): boolean;
}