import { createReadStream } from 'fs';
export declare function extensionForMime(mimetype: string | undefined): string;
export declare function isSafeMediaFileId(fileId: string): boolean;
export declare function mimeForFileId(fileId: string): string;
export declare class UltramsgMediaService {
    private readonly logger;
    private readonly dir;
    mediaBaseUrl(): string;
    absoluteMediaUrl(fileId: string): string;
    saveInbound(media: {
        mimetype?: string;
        data?: string;
        omitted?: boolean;
    } | undefined): string;
    resolvePath(fileId: string): string;
    open(fileId: string): {
        stream: ReturnType<typeof createReadStream>;
        mime: string;
    };
}