import { NormalizedEmail, EmailStreamOptions, EmailStreamCallbacks, EmailStreamProgress, EmailStreamBatch } from '../interfaces.js';
/**
 * Common streaming utility for email adapters
 * Provides shared functionality for streaming emails in batches
 */
export declare class EmailStreamService {
    /**
     * Creates an async generator that yields email batches
     * This is the core streaming implementation that adapters can use
     */
    static createEmailStream(fetchPageFn: (pageToken?: string, pageSize?: number) => Promise<{
        emails: NormalizedEmail[];
        nextPageToken?: string;
        totalCount?: number;
    }>, options: EmailStreamOptions): AsyncGenerator<NormalizedEmail[], void, unknown>;
    /**
     * Executes email streaming with callbacks for progress tracking
     */
    static processEmailStream(streamGenerator: AsyncGenerator<NormalizedEmail[], void, unknown>, callbacks: EmailStreamCallbacks): Promise<void>;
    /**
     * Utility to create a stream batch object with metadata
     */
    static createStreamBatch(emails: NormalizedEmail[], batchNumber: number, progress: EmailStreamProgress, isLastBatch?: boolean): EmailStreamBatch;
    /**
     * Utility to calculate estimated remaining emails
     */
    static calculateEstimatedRemaining(totalCount: number | undefined, currentProcessed: number): number | undefined;
    /**
     * Utility to validate streaming options
     */
    static validateStreamOptions(options: EmailStreamOptions): void;
}