/**
 * MercadoPago webhook signature validator.
 *
 * Verifies the authenticity of incoming webhook notifications by recomputing
 * the HMAC-SHA256 signature locally and comparing it against the value carried
 * in the `x-signature` header. The implementation is stateless, performs no
 * outbound HTTP calls, and does not depend on `MercadoPagoConfig` — the
 * integrator passes the secret signature explicitly on every call.
 *
 * @module utils/webhook
 */
/**
 * Enumerates the reasons why {@link WebhookSignatureValidator} may reject a
 * MercadoPago webhook notification.
 *
 * Each value maps to a specific failure mode in the signature verification flow.
 * Integrators are encouraged to log this value alongside the
 * `x-request-id` for correlation against the MercadoPago notifications dashboard.
 */
export declare enum SignatureFailureReason {
    /** The `x-signature` header was missing, empty, or whitespace. */
    MissingSignatureHeader = "MissingSignatureHeader",
    /**
     * The `x-signature` header did not match the expected `ts=...,vN=...`
     * format and could not be parsed.
     */
    MalformedSignatureHeader = "MalformedSignatureHeader",
    /** The header parsed correctly but no `ts=` component was present. */
    MissingTimestamp = "MissingTimestamp",
    /**
     * The header did not include a hash for any of the versions listed in
     * `supportedVersions`. Typically indicates that MercadoPago has migrated to
     * a new signature version (e.g. `v2`) and the SDK needs to be upgraded.
     */
    MissingHash = "MissingHash",
    /**
     * The HMAC computed locally did not match the hash provided in the header.
     * Most often caused by an incorrect secret signature or by a forged request.
     */
    SignatureMismatch = "SignatureMismatch",
    /**
     * The header timestamp was outside the configured `tolerance` window
     * against the current clock. May indicate clock drift on the integrator's
     * server or a replay attack.
     */
    TimestampOutOfTolerance = "TimestampOutOfTolerance"
}
/**
 * Error thrown by {@link WebhookSignatureValidator.validate} when a webhook
 * notification cannot be confirmed as originating from MercadoPago.
 *
 * The instance carries enough context to support structured logging without
 * exposing internal details in the HTTP response.
 */
export declare class InvalidWebhookSignatureError extends Error {
    /** The specific failure mode that triggered the error. */
    readonly reason: SignatureFailureReason;
    /** The `x-request-id` header value, when available at the point of failure. */
    readonly requestId?: string;
    /** The `ts` value extracted from the `x-signature` header, when parsing reached that point. */
    readonly timestamp?: string;
    constructor(reason: SignatureFailureReason, requestId?: string, timestamp?: string);
}
/**
 * Arguments accepted by {@link WebhookSignatureValidator.validate}.
 *
 * Header and query values may be `string | string[] | null | undefined` to match
 * the loose shapes that web frameworks (Express, Fastify, etc.) commonly produce.
 * The validator normalises them internally.
 */
export interface ValidateOptions {
    /** Raw value of the `x-signature` request header. */
    xSignature: string | string[] | undefined | null;
    /** Raw value of the `x-request-id` request header. */
    xRequestId: string | string[] | undefined | null;
    /** Value of the `data.id` query string parameter. */
    dataId: string | string[] | undefined | null;
    /** Secret signature configured for the application in Tus Integraciones. */
    secret: string;
    /**
     * Optional maximum allowed drift in seconds between the timestamp in the
     * header and `Date.now()`. Setting a small window (e.g. 300 seconds)
     * mitigates replay attacks. Omit to skip the check.
     */
    toleranceSeconds?: number;
    /**
     * Optional ordered list of signature versions the validator will accept.
     * Defaults to `['v1']`. The validator iterates in order and uses the first
     * version found in the header, allowing forward compatibility with future
     * signature schemes (e.g. `v2`) without breaking older integrations.
     */
    supportedVersions?: string[];
    /**
     * Optional clock function used for the tolerance check. Defaults to
     * `Date.now`. Intended for tests; production code should not override.
     */
    now?: () => number;
}
/**
 * Stateless utility that validates the signature of a MercadoPago webhook.
 *
 * On failure it throws {@link InvalidWebhookSignatureError}; on success it
 * returns nothing. The comparison is performed in constant time to mitigate
 * timing attacks.
 *
 * QR Code notifications are **not signed** by MercadoPago — do not call this
 * validator for those events; they will always fail signature verification.
 */
export declare class WebhookSignatureValidator {
    /**
     * Validates the signature of a MercadoPago webhook notification.
     *
     * @param options - Validation inputs (see {@link ValidateOptions}).
     * @throws {@link InvalidWebhookSignatureError} when the signature is missing,
     *   malformed, or does not match the expected HMAC.
     */
    static validate(options: ValidateOptions): void;
}