import { IncomingFile, PresignedUpload, StoredObject } from './file.interface';
export interface ExistsResult {
    exists: boolean;
    size?: number;
    contentType?: string;
}
/**
 * The pluggability core. Every storage backend (Azure Blob, S3, local disk, or a
 * user-supplied class) implements this contract; the rest of the pipeline is agnostic.
 */
export interface StorageAdapter {
    readonly name: string;
    upload(file: IncomingFile, key: string, meta?: Record<string, string>): Promise<StoredObject>;
    download(key: string): Promise<NodeJS.ReadableStream>;
    delete(key: string): Promise<void>;
    exists(key: string): Promise<ExistsResult>;
    /** Presigned PUT URL for client-direct upload. */
    getSignedUploadUrl(key: string, opts: {
        expiresIn: number;
        contentType?: string;
    }): Promise<PresignedUpload>;
    /** Presigned/SAS GET URL for reads under urlMode:'signed'. */
    getSignedDownloadUrl(key: string, opts: {
        expiresIn: number;
    }): Promise<string>;
    copy(srcKey: string, destKey: string): Promise<void>;
    /** Permanent public URL (used under urlMode:'public'). */
    publicUrl(key: string): string;
    /** Read the first bytes of an object — used to magic-sniff a presigned upload at confirm time. */
    readRange(key: string, start: number, end: number): Promise<Buffer>;
}