import { FeedEntry } from "./feed_entry";
/**
 * Represents a feed store.
 *
 * A feed store can save and load feeds.
 * Order of feeds must be kept.
 */
export interface FeedStore {
    /**
     * Load the ETag info.
     * The implementation of this can be omit.
     * If it is omitted, this always returns an empty string.
     *
     * @returns ETag.
     */
    loadETag(): string;
    /**
     * Save the ETag info.
     * The implementation of this can be omit.
     * If it is omitted, this does nothing.
     *
     * @param etag - ETag.
     */
    saveETag(etag: string): void;
    /**
     * Get the feed count of store.
     *
     * @returns feed count.
     */
    getFeedCount(): number;
    /**
     * Load the latest n feeds.
     *
     * @param n - Count of feeds.
     * @returns Loaded feeds.
     */
    loadFeeds(n: number): FeedEntry[];
    /**
     * Save new feeds.
     * This does not care the feed's ID.
     * Always stored all feeds.
     *
     * @param feeds - Feeds to save.
     */
    saveFeeds(feeds: FeedEntry[]): void;
    /**
     * Return true if there is no feeds in this store.
     *
     * @returns Store is empty or not.
     */
    isEmpty(): boolean;
    /**
     * Clear all stored feeds.
     */
    clear(): void;
}