import { AttachedFile } from './types';
import { MenuItemType } from '../Menu/types';
/**
 * Determine the file type from a File object
 */
export declare const getFileType: (file: File) => AttachedFile["type"];
/**
 * Create menu items for overflow files
 */
export declare const createOverflowMenuItems: (hiddenFiles: AttachedFile[], onFileRemove: (fileId: string) => void, onFileClick: (file: AttachedFile) => void) => MenuItemType[];
/**
 * Handle textarea auto-resize functionality
 */
export declare const handleAutoResize: (element: HTMLTextAreaElement | null, autoResize: boolean) => void;
/**
 * Validate message length against maxLength
 */
export declare const isValidMessageLength: (message: string, maxLength?: number) => boolean;
/**
 * Convert File objects to AttachedFile objects
 */
export declare const convertFilesToAttachedFiles: (files: File[]) => AttachedFile[];
/**
 * Filter out duplicate files by comparing name and size with existing attached files
 * @param files - Array of File objects to check
 * @param attachedFiles - Array of already attached files
 * @returns Object containing newFiles (non-duplicates) and duplicateFiles (array of duplicate file names)
 */
export declare const filterDuplicateFiles: (files: File[], attachedFiles: AttachedFile[]) => {
    newFiles: File[];
    duplicateFiles: string[];
};
/**
 * Simple utility to truncate placeholder text if it exceeds the textarea's available width
 * Uses canvas to measure text width and truncates with ellipsis if needed
 */
export declare const truncatePlaceholder: (textarea: HTMLTextAreaElement | null, placeholder: string | undefined) => string | undefined;