/**
 * @fileoverview File helpers shared by the upload components: size formatting,
 * extension parsing and file-type icon resolution.
 */
import type { IconName } from '../components/nv-icon/nv-icons';
/** Icon shown when the file type has no dedicated glyph. */
export declare const DEFAULT_FILE_ICON: `${IconName}`;
/** Icon shown for a file rejected by validation. */
export declare const INVALID_FILE_ICON: `${IconName}`;
/**
 * Returns the lowercase extension of a file name, without the dot.
 *
 * @param {string} [fileName] - The file name, e.g. "report.PDF".
 * @returns {string} The extension ("pdf"), or an empty string when there is none.
 */
export declare function getFileExtension(fileName?: string): string;
/**
 * Normalizes a file type to an extension. Accepts an extension ("pdf",
 * ".pdf") or a MIME type ("application/pdf").
 *
 * @param {string} [fileType] - The extension or MIME type.
 * @returns {string} The lowercase extension, or an empty string.
 */
export declare function normalizeFileType(fileType?: string): string;
/**
 * Resolves the icon for a file. The explicit type wins over the file name;
 * when the type has no dedicated icon, the extension of the name is used.
 *
 * @param {string} [fileName] - The file name, used when the type gives no icon.
 * @param {string} [fileType] - An extension or MIME type.
 * @returns {IconName} The matching `file-type-*` icon, or the generic file icon.
 */
export declare function getFileTypeIcon(fileName?: string, fileType?: string): `${IconName}`;
/**
 * Formats a size in bytes for display, using binary multiples (1 MB =
 * 1 048 576 bytes) and the units of the given locale ("1.2 MB", "1,2 Mo").
 *
 * @param {number} bytes - The size in bytes.
 * @param {string} [locale] - Locale override. Defaults to the browser locale.
 * @returns {string} The formatted size, or an empty string for an invalid value.
 */
export declare function formatFileSize(bytes: number, locale?: string): string;
/**
 * Reads the files carried by a drag-and-drop or clipboard transfer. Dropped
 * folders are skipped: only real files are returned.
 *
 * @param {DataTransfer | null} [transfer] - The `dataTransfer` or `clipboardData` of the event.
 * @returns {File[]} The files, in the order they were provided.
 */
export declare function getTransferFiles(transfer?: DataTransfer | null): File[];
/** Number of bytes in one megabyte, as used by `maxFileSize` (binary). */
export declare const BYTES_PER_MEGABYTE: number;
/**
 * Splits an `accept` value into its lowercase tokens.
 *
 * @param {string} [accept] - Comma-separated MIME types and extensions.
 * @returns {string[]} The tokens, without empty entries.
 */
export declare function parseAccept(accept?: string): string[];
/**
 * What `matchesAccept` needs to know about a file. A browser `File` fits.
 */
export interface AcceptCandidate {
    /** Name of the file, extension included. */
    name: string;
    /** MIME type reported by the browser, when it knows it. */
    type?: string;
}
/**
 * Tells whether a file matches an `accept` value, with the same rules as the
 * native file input: extensions (".pdf"), exact MIME types
 * ("application/pdf") and wildcards ("image/*"). When the browser reports no
 * MIME type, the extension of the file name is used instead.
 *
 * @param {AcceptCandidate} file - The file to check.
 * @param {string} [accept] - Comma-separated MIME types and extensions.
 * @returns {boolean} True when the file is accepted, or when `accept` is empty.
 */
export declare function matchesAccept(file: AcceptCandidate, accept?: string): boolean;
/**
 * Lists the file types of an `accept` value in a form fit for display:
 * uppercase extensions ("PDF", "JPG") and, for wildcards, the category
 * followed by "/*" ("image/*"). Duplicates such as ".jpg" and "image/jpeg"
 * are merged.
 *
 * @param {string} [accept] - Comma-separated MIME types and extensions.
 * @returns {string[]} The display labels, in the order they were declared.
 */
export declare function getAcceptLabels(accept?: string): string[];