import { HRef, HDict, HGrid } from 'haystack-core';
import { WatchChangedEvent } from './WatchEvent';
/**
 * The subject changed event callback handler.
 */
export interface SubjectChangedEventHandler {
    (event: WatchChangedEvent): void;
}
/**
 * A subject is observed by a watch.
 */
export interface Subject {
    /**
     * The display name of the subject.
     */
    readonly display: string;
    /**
     * The subject's poll rate.
     */
    pollRate: number;
    /**
     * Refresh the subject's data.
     */
    refresh(): Promise<void>;
    /**
     * Add records to observe.
     *
     * @param ids The ids to add.
     */
    add(ids: string[]): Promise<void>;
    /**
     * Remove records from the subject.
     *
     * This is called to stop observing records.
     *
     * @param ids The ids to remove.
     */
    remove(ids: string[]): Promise<void>;
    /**
     * Register a callback for changed events.
     *
     * @param callback The callback used for changed events.
     */
    on(callback: SubjectChangedEventHandler): void;
    /**
     * Unregister the callback for changed events.
     *
     * @param callback The callback used for changed events.
     */
    off(callback: SubjectChangedEventHandler): void;
    /**
     * Return a record via its id or undefined if it can't be found.
     *
     * @param id The id to record to get.
     * @returns The dict or undefined if it can't be found.
     */
    get(id: string | HRef): HDict | undefined;
    /**
     * Used to manually trigger a watch update.
     *
     * @param grid A grid of dicts to update.
     */
    update(grid: HGrid): Promise<void>;
    /**
     * Inspect the subject.
     */
    inspect(): void;
}