import { StorageBackend, StorageResult, R2StorageConfig, StorageUploadOptions } from './base';
/**
 * Cloudflare R2 Storage Backend
 * R2 is S3-compatible, but uses a specific endpoint format
 */
export declare class R2StorageBackend implements StorageBackend {
    private config;
    readonly type: "r2";
    readonly hasPublicUrl = true;
    private endpoint;
    constructor(config: R2StorageConfig);
    init(): Promise<void>;
    upload(buffer: Buffer, filename: string): Promise<StorageResult>;
    uploadStream(stream: NodeJS.ReadableStream, filename: string, options?: StorageUploadOptions): Promise<StorageResult>;
    download(key: string): Promise<Buffer>;
    downloadStream(key: string): NodeJS.ReadableStream;
    delete(key: string): Promise<void>;
    exists(key: string): Promise<boolean>;
    private generateAuthorizationHeader;
    private getSigningKey;
}