import type { SocketAdapter, TLSOptions } from "../core/types.js";
/** Configuration options for {@link NodeAdapter}. */
export interface NodeAdapterOptions {
    /** Use implicit TLS on connect (port 465). Default: false. */
    secure?: boolean;
    /** Socket connect timeout in milliseconds. Default: 30_000. */
    connectionTimeout?: number;
    /** TLS options passed to node:tls. */
    tls?: TLSOptions;
}
/**
 * Node.js socket adapter using node:net and node:tls.
 */
export declare class NodeAdapter implements SocketAdapter {
    /** Underlying Node.js TCP or TLS socket. */
    private socket;
    /** Whether the connection is currently encrypted. */
    private _secure;
    /** Whether the socket is connected. */
    private _connected;
    /** Socket connect timeout in milliseconds. */
    private readonly connectionTimeout;
    /** TLS options for direct TLS and STARTTLS upgrades. */
    private readonly tlsOptions;
    /** Creates a Node.js socket adapter. */
    constructor(options?: NodeAdapterOptions);
    /** Whether the connection uses TLS. */
    get secure(): boolean;
    /** Whether the socket is currently connected. */
    get connected(): boolean;
    /** Opens a TCP or TLS connection to the given host and port. */
    connect(host: string, port: number): Promise<void>;
    /** Upgrades a plain connection to TLS via STARTTLS. */
    startTLS(options?: TLSOptions): Promise<void>;
    /** Writes raw bytes to the socket. */
    write(data: Uint8Array): Promise<void>;
    /** Reads incoming socket data as an async iterable of byte chunks. */
    read(): AsyncGenerator<Uint8Array, void, unknown>;
    /** Closes the socket connection. */
    close(): Promise<void>;
    /** Opens a plain TCP connection to the SMTP server. */
    private connectPlain;
    /** Opens a direct TLS connection to the SMTP server. */
    private connectTls;
}