import { ILogger } from './types';
import { EventEmitter } from './event-emitter';
/**
 * SSE event types supported by FlagStreamClient
 */
export interface SSEvent {
    type: string;
    data: unknown;
    id?: string;
}
/**
 * Options for creating an SSE client
 */
export interface SSEClientOptions {
    url: string;
    apiKey?: string;
    headers?: Record<string, string>;
    lastEventId?: string;
    logger: ILogger;
    events: EventEmitter;
    onConnected?: () => void;
    onError?: (error: Error) => void;
    onMessage?: (data: unknown) => void;
    /** Called when an SSE event with an id field is received, passing the id value */
    onEventId?: (id: string) => void;
}
/**
 * Result of starting an SSE connection
 */
export interface SSEResult {
    abort: () => void;
}
/**
 * SSE Client that uses fetch with ReadableStream for authentication.
 * This avoids sending credentials in the URL.
 */
export declare class SSEClient {
    private readonly options;
    private abortController;
    private disposed;
    constructor(options: SSEClientOptions);
    /**
     * Start the SSE connection using fetch
     */
    connect(): SSEResult | null;
    private startFetch;
    private processStream;
    private handleSSEvent;
    /**
     * Extract slugs from SSE message data.
     * Supports formats:
     * - { slug: 'checkout-v2', action: 'updated' } → ['checkout-v2']
     * - { slugs: ['a', 'b'], action: 'batch' } → ['a', 'b']
     * - Legacy messages without slug info → undefined (triggers full cache clear)
     */
    private extractSlugsFromMessage;
    /**
     * Abort the current connection
     */
    abort(): void;
    /**
     * Mark as disposed — prevents reconnection
     */
    dispose(): void;
}