export interface LinkPreviewData {
    url: string;
    title: string | null;
    description: string | null;
    image: string | null;
    imageWidth: number | null;
    imageHeight: number | null;
    siteName: string | null;
    favicon: string | null;
    imageAlt?: string | null;
    /** The colour the page declares for itself, used when we know no brand. */
    themeColor?: string | null;
    /** `og:type`: "article", "video.other", "music.song". */
    type?: string | null;
    author?: string | null;
    publishedAt?: string | null;
    /** Present when the page advertises a real player. */
    oembedUrl?: string | null;
    /** What the page answered with, so a 404 can say so rather than guess. */
    status?: number | null;
}
/**
 * The links in a message, minus the ones that are already something else: a URL in backticks
 * is being quoted rather than shared, and a markdown image is already drawn.
 */
export declare function extractUrls(text: string | null): string[];
/**
 * How much of a card a preview can fill. A wide image sits under the text, a small one
 * beside it, and no image takes no space — drawing all three alike gave a grey rectangle.
 */
export type LinkCardLayout = "large" | "thumbnail" | "text" | "bare";
export declare function getLinkCardLayout(data: LinkPreviewData): LinkCardLayout;
/**
 * Why a page gave us nothing, in words worth showing somebody. Only for statuses that mean
 * something to a reader: a 500 is the site's problem, so it returns null.
 */
export declare function describePreviewFailure(status: number | null | undefined): string | null;
/**
 * The line under the title, where the path says something the title does not. Wikipedia
 * titles its WebRTC page "WebRTC", and `/wiki/WebRTC` printed the word twice.
 */
export declare function getCardSubtitle(title: string | null, detail: string | null): string | null;