import type { ValidateEmailOptions } from '../../types';
/** Hard limit on batch size enforced by every adapter. */
export declare const MAX_BATCH_SIZE = 100;
/** Shape of POST bodies and Lambda invocations across all serverless adapters. */
export interface ValidationRequestBody {
    email?: string;
    emails?: string[];
    options?: ValidateEmailOptions;
}
export type ValidationDispatch = {
    kind: 'single';
    email: string;
    options?: ValidateEmailOptions;
} | {
    kind: 'batch';
    emails: string[];
    options?: ValidateEmailOptions;
};
export interface ValidationFailure {
    kind: 'invalid';
    status: 400;
    message: string;
}
/**
 * Validation for endpoints that accept ONLY a batch (`emails`). Returns
 * a 400 failure if emails is missing/empty/oversized, or null when valid.
 * Routed `/validate/batch` paths use this so error messages stay batch-specific.
 */
export type BatchValidation = {
    ok: true;
    emails: string[];
} | {
    ok: false;
    status: 400;
    message: string;
};
export declare function validateBatchEmailsField(emails: unknown): BatchValidation;
/**
 * Apply the rules every serverless adapter shares:
 *   1. body must request either `email` or `emails`
 *   2. `emails` must be a non-empty array of ≤ MAX_BATCH_SIZE entries
 *
 * Centralising this means a future rule change (say, raising the cap) lands
 * in one place instead of three.
 */
export declare function classifyRequest(body: ValidationRequestBody | null | undefined): ValidationDispatch | ValidationFailure;