/**
 * @module
 * Cloudflare Workers socket adapter for SMTP via cloudflare:sockets.
 *
 * @example
 * ```ts
 * import { CloudflareAdapter } from "sently/adapters/cf";
 * import { createSMTPMailer } from "sently/smtp";
 *
 * const mailer = await createSMTPMailer({
 *   host: "smtp.example.com",
 *   adapter: new CloudflareAdapter(),
 *   auth: { user: "relay@example.com", pass: "secret" },
 * });
 * ```
 */
import type { SocketAdapter, TLSOptions } from "../core/types.js";
/** Configuration options for {@link CloudflareAdapter}. */
export interface CloudflareAdapterOptions {
    /** Use implicit TLS on connect (secureTransport: "on"). Default: false. */
    secure?: boolean;
    /** Enable STARTTLS upgrade after plain connect. Default: true when not secure. */
    starttls?: boolean;
    /** Reserved for future TLS tuning (Workers sockets API). */
    tls?: TLSOptions;
}
/**
 * Cloudflare Workers socket adapter via cloudflare:sockets.
 *
 * Limitations:
 * - No connection pooling (isolate lifecycle)
 * - No file system access for attachment.path
 * - No DNS MX lookup — explicit SMTP relay host required
 */
export declare class CloudflareAdapter implements SocketAdapter {
    /** Underlying Cloudflare Workers socket. */
    private socket;
    /** Writable stream writer for outbound bytes. */
    private writer;
    /** Whether the connection is currently encrypted. */
    private _secure;
    /** Whether the socket is connected. */
    private _connected;
    /** Whether implicit TLS is used on connect (port 465 style). */
    private readonly directTls;
    /** Whether STARTTLS upgrade is enabled after plain connect. */
    private readonly starttls;
    /** Creates a Cloudflare Workers socket adapter. */
    constructor(options?: CloudflareAdapterOptions);
    /** 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>;
}