import type { MqttClient } from "mqtt";
/** What became of a publish. A failure is a value: publish() never rejects. */
export type PublishResult = {
    ok: true;
    topic: string;
} | {
    ok: false;
    topic: string;
    error: Error;
};
/** Where the bridge, its devices and their messages publish. The message is sent as JSON. */
export interface Publisher {
    publish(topic: string, message: object): Promise<PublishResult>;
}
/**
 * Publishes to the broker through the client the bridge has at the time: a new one after disconnect() and connect(),
 * none before connect() and after disconnect(). Without a client the publish is refused. With a client that lost
 * its connection mqtt.js keeps the message and sends it after the reconnect, and the publish resolves then.
 */
export declare class MqttPublisher implements Publisher {
    private readonly client;
    constructor(client: () => MqttClient | null);
    publish(topic: string, message: object): Promise<PublishResult>;
}
/**
 * Keeps what it is asked to publish, for tests and dry runs without a broker:
 *
 *   const sent = new MemoryPublisher();
 *   device.publisher = sent;
 *   await device.getStatusMessage(token, true).addPowerControllerProp(PowerController.ON).send();
 *   sent.published[0]   // { topic: "<root>/<endpointId>/alexaResponce", message: { event, context } }
 */
export declare class MemoryPublisher implements Publisher {
    /** Oldest first. The message is what a subscriber gets after JSON.parse. */
    readonly published: Array<{
        topic: string;
        message: any;
    }>;
    /** Set it and every publish fails with this error, as a publish to a broker that is gone does. */
    failWith: Error | null;
    publish(topic: string, message: object): Promise<PublishResult>;
}
/**
 * send() as 1.x promises it: resolves with the topic, or with "" when nothing was published, and never rejects
 * (1.5.1 rejected, and a send() nobody caught killed the host on any broker hiccup). What went wrong goes to report:
 * the message cannot be built, the device is on no bridge, or the publish failed.
 */
export declare function send(publisher: Publisher | null, topic: string, build: () => object, report?: (err: Error) => void): Promise<string>;