/**
 * Utility functions for SD metadata parsing
 * Common utilities used across different format parsers
 */
/**
 * Decode data URI to buffer
 */
export declare function decodeDataUri(value: string): Buffer | null;
/**
 * Convert base64 string to buffer
 */
export declare function bufferFromBase64(value: string): Buffer | null;
/**
 * Detect image format from buffer
 */
export declare function detectImageFormat(buffer: Buffer): 'png' | 'webp' | 'jpeg' | null;
/**
 * Normalize local file path
 */
export declare function normalizeLocalPath(target: string): string | null;
/**
 * Try to read local file as buffer
 */
export declare function tryReadLocalFileBuffer(target: string): Promise<Buffer | null>;
/**
 * Guess file extension from various attributes
 */
export declare function guessFileExtension(attrs: Record<string, any>, sourceHint?: string): string;
/**
 * Check if a value is a valid URL
 */
export declare function isValidUrl(value: string): boolean;
/**
 * Normalize URL for deduplication (sort query params)
 */
export declare function normalizeUrl(url?: string): string;
/**
 * Create a unique key for an image segment
 */
export declare function makeImageSegmentKey(segment: {
    attrs?: Record<string, any>;
    data?: Record<string, any>;
}): string;
/**
 * Simple LRU cache implementation
 */
export declare class LRUCache<K, V> {
    private cache;
    private readonly maxSize;
    constructor(maxSize?: number);
    get(key: K): V | undefined;
    set(key: K, value: V): void;
    has(key: K): boolean;
    clear(): void;
    get size(): number;
}
/**
 * Validation helpers
 */
export declare class Validation {
    static isString(value: any): value is string;
    static isNumber(value: any): value is number;
    static isObject(value: any): value is Record<string, any>;
    static isBuffer(value: any): value is Buffer;
    static isNonEmptyString(value: any): value is string;
}
/**
 * Parse metadata value safely
 */
export declare function parseMetadataValue<T>(value: any, parser: (v: any) => T | null): T | undefined;
/**
 * Get nested object value safely
 */
export declare function getNestedValue(obj: any, path: string): any;
export type { ImageSegment } from './types';