import { AcceptedImageOutputFormats, FitEnum, type ApproveDomainFunction, type Options } from '../data.js';
import type { RequestEvent } from '@sveltejs/kit';
import { PassThrough } from 'stream';
export declare function _extractRequiredParams(event: RequestEvent, options: Options): {
    url: string | null;
    width: string | null;
    height: string | null;
    format: AcceptedImageOutputFormats;
    quality: number;
    fit: FitEnum;
    position: string;
    background: string | undefined;
    hasResize: string | null;
};
export declare function _shouldSkip(sourceFormat: string, options: Options, acceptHeaders: string): boolean;
export declare function _createHashString(str: string): string;
export declare function _peekStream(stream: ReadableStreamDefaultReader<Uint8Array<ArrayBufferLike>>, byteCount?: number): Promise<{
    peekedBuffer: Buffer<ArrayBuffer>;
    remainingStream: ReadableStreamDefaultReader<Uint8Array<ArrayBufferLike>>;
}>;
export declare function _finishRemainingStream(remainingStream: ReadableStreamDefaultReader<Uint8Array<ArrayBufferLike>>, peekedBuffer: Buffer): PassThrough;
export declare function _createStreamResponse(stream: NodeJS.ReadableStream, headers: HeadersInit): Response;
export declare function _validateUrl(url: string | null): string | undefined;
export declare function _isAllowedDomain(url: string, allowedDomains: Array<string | RegExp> | ApproveDomainFunction | undefined): boolean;
export declare function _isRelativeURL(url: string | null): boolean;
export declare function _extractBackgroundColor(color: string | null): string | undefined;
export declare function _extractTTLFromCacheControlHeader(cacheControlHeader: string): number;
export declare function _getCacheControlHeader(ttl: number): string;
export declare function _validateAndGetOptions(options?: Partial<Options>): Readonly<{
    route: string;
    formatPriority: AcceptedImageOutputFormats[];
    fallbackFormat: string;
    quality: number | undefined;
    cache: import("../data.js").ImageCacheHandler | undefined;
    cacheTTLStrategy: number | "source" | "immutable" | "no-cache";
    allowedDomains: (string | RegExp)[] | ApproveDomainFunction;
    minSizeThreshold: number;
    skipFormats: AcceptedImageOutputFormats[];
}>;