/**
 * WebSocket Transport Adapter
 *
 * WebSocket transport for real-time bidirectional streaming.
 * Provides an alternative to SSE with support for client-to-server messages.
 *
 * NOTE: This is a placeholder implementation. Full WebSocket support requires
 * runtime-specific handling (Node.js 'ws' package, Bun/Deno native WebSocket, etc.)
 *
 * For production use:
 * - Node.js: Use 'ws' package with HTTP upgrade
 * - Bun: Use Bun.serve with websocket option
 * - Deno: Use Deno.upgradeWebSocket
 * - Next.js: WebSocket requires custom server, not supported in serverless
 */
import type { StreamMessage, StreamTransportAdapterConfig } from '@plyaz/types/core';
import { BaseTransportAdapter } from '../BaseTransportAdapter';
/**
 * WebSocketTransportAdapter - WebSocket transport
 *
 * Features:
 * - Bidirectional communication
 * - Automatic heartbeat (ping/pong)
 * - JSON message formatting
 * - Connection cleanup on disconnect
 *
 * @example
 * ```ts
 * // With Bun
 * const wsAdapter = new WebSocketTransportAdapter();
 *
 * Bun.serve({
 *   fetch(req, server) {
 *     const success = server.upgrade(req, { data: { connectionId } });
 *     if (success) return undefined;
 *     return new Response('WebSocket upgrade failed', { status: 400 });
 *   },
 *   websocket: {
 *     open(ws) { wsAdapter.registerConnection(connectionId, ws); },
 *     message(ws, message) { wsAdapter.handleMessage(connectionId, message); },
 *     close(ws) { wsAdapter.close(connectionId); },
 *   },
 * });
 * ```
 */
export declare class WebSocketTransportAdapter extends BaseTransportAdapter {
    private connections;
    constructor(config?: Partial<StreamTransportAdapterConfig>);
    /**
     * Create a new WebSocket connection.
     *
     * NOTE: In most runtimes, WebSocket connections are created via HTTP upgrade,
     * not through this method directly. Use registerConnection() instead.
     *
     * @param _connectionId - Unique connection identifier
     * @returns Response indicating WebSocket upgrade is needed
     */
    createConnection(_connectionId: string): Promise<Response>;
    /**
     * Register an already-upgraded WebSocket connection.
     * Call this from your runtime's WebSocket open handler.
     *
     * @param connectionId - Unique connection identifier
     * @param socket - The WebSocket instance
     */
    registerConnection(connectionId: string, socket: WebSocket): void;
    /**
     * Handle incoming message from WebSocket.
     * Call this from your runtime's WebSocket message handler.
     *
     * @param _connectionId - Connection that sent the message
     * @param message - Raw message data
     * @returns Parsed message or null if invalid
     */
    handleMessage(_connectionId: string, message: string | ArrayBuffer): StreamMessage | null;
    /**
     * Send a message to a connection.
     *
     * @param connectionId - Connection to send to
     * @param message - Message to send
     */
    send(connectionId: string, message: StreamMessage): Promise<void>;
    /**
     * Close a connection.
     *
     * @param connectionId - Connection to close
     */
    close(connectionId: string): Promise<void>;
    /**
     * Check if a connection is alive.
     *
     * @param connectionId - Connection to check
     */
    isAlive(connectionId: string): boolean;
    /**
     * Get current connection count.
     */
    getConnectionCount(): number;
    /**
     * Get all connection IDs.
     */
    getConnectionIds(): string[];
    /**
     * Send message immediately to socket.
     */
    private sendImmediate;
    /**
     * Cleanup connection resources.
     */
    private cleanup;
    /**
     * Close all connections (for shutdown).
     */
    closeAll(): Promise<void>;
}
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