import { E as EmailOptions, a as EmailResult, R as Result } from "./types.d-CyiC9uRC.js";
/**
 * The terminal send function a middleware wraps — ultimately the provider's `sendEmail`.
 */
type SendFunction = (options: EmailOptions) => Promise<Result<EmailResult>>;
/**
 * A send middleware. Receives the (fully-resolved) message and the `next` function in the chain;
 * may short-circuit, retry, mutate, or observe.
 *
 * Middlewares run in registration order, wrapping outward-in (the first registered runs first and is
 * the outermost wrapper around the provider call).
 * @param options The resolved email options.
 * @param next The next middleware (or the provider send) in the chain.
 * @returns The send result.
 */
type Middleware = (options: EmailOptions, next: SendFunction) => Promise<Result<EmailResult>>;
/**
 * Composes a middleware stack around a terminal send function.
 * @param middlewares The middlewares, in registration order.
 * @param terminal The provider send call at the centre of the chain.
 * @returns A single {@link SendFunction} that runs the whole chain.
 */
declare const composeMiddleware: (middlewares: ReadonlyArray<Middleware>, terminal: SendFunction) => SendFunction;
export { Middleware as M, SendFunction as S, composeMiddleware as c };