import type { BasePlaylistItem } from '@nomercy-entertainment/nomercy-player-core';
/**
 * A resolved thumbnail for a specific time offset.
 *
 * The sprite coordinates (`x`, `y`, `w`, `h`) describe the sub-region of
 * `spriteUrl` to render. All four are zero when the source is a per-frame
 * standalone image (non-sprite VTT) or when the adapter packs one image
 * per cue.
 */
export interface ThumbnailFrame {
    /** URL of the sprite image (or standalone frame image). */
    spriteUrl: string;
    /** Left offset within the sprite, in pixels. */
    x: number;
    /** Top offset within the sprite, in pixels. */
    y: number;
    /** Width of the sub-region, in pixels. */
    w: number;
    /** Height of the sub-region, in pixels. */
    h: number;
    /** Cue start time in seconds. */
    start: number;
    /** Cue end time in seconds. */
    end: number;
}
/**
 * Contract for anything that can supply thumbnail frames for a playlist item.
 *
 * Implementations are registered on the player and queried when the user
 * hovers the progress bar. The default implementation (`VttSpriteThumbnailSource`)
 * fetches a WebVTT sprite manifest and parses it into `ThumbnailFrame` objects.
 */
export interface IThumbnailSource {
    /**
     * Load thumbnails for a playlist item. Called once per item when the
     * backend fires `loadedmetadata`. Implementations should fetch and cache
     * the data here — `lookup` must be synchronous.
     *
     * @returns `true` when thumbnails are available for this item, `false` when
     *   the item has no thumbnail source (e.g. no `previewSpriteUrl` field).
     */
    load(item: BasePlaylistItem): Promise<boolean>;
    /**
     * Return the thumbnail frame covering `timeSeconds`, or `null` when no
     * frame is available. Must be synchronous — called on every scrub event.
     */
    lookup(timeSeconds: number): ThumbnailFrame | null;
    /** Release any cached data for the current item. Called on unload/dispose. */
    unload(): void;
}