/**
 * Teacher avatar upload utility
 * Handles client-side file validation, WebP conversion, and upload orchestration
 */
/**
 * Validation error type
 */
export interface AvatarUploadError {
    type: "size" | "format" | "conversion" | "unknown";
    message: string;
}
/**
 * Result of avatar upload process
 */
export interface AvatarUploadResult {
    success: true;
    fileBase64: string;
    contentType: "image/webp";
    originalFileName: string;
}
/**
 * Validate file size and format
 */
export declare function validateAvatarFile(file: File): AvatarUploadError | null;
/**
 * Convert image file to WebP format
 */
export declare function convertToWebPFormat(file: File): Promise<Blob | AvatarUploadError>;
/**
 * Convert blob to base64 string
 */
export declare function blobToBase64(blob: Blob): Promise<string>;
/**
 * Process avatar file: validate, convert to WebP, return base64
 */
export declare function processAvatarFile(file: File): Promise<AvatarUploadResult | AvatarUploadError>;