import type { CreateChallengeOptions, DeriveKeyFunction, Payload, ServerSignaturePayload, SetCookieOptions, VerifyServerOptions, VerifyServerResult, VerifySolutionResult } from '../types.js';
export type AltchaVerifyServerOptions = Omit<VerifyServerOptions, 'payload'>;
export interface AltchaOptions {
    /**
     * Returns configuration options passed to `createChallenge`.
     * Must include `algorithm` and `cost`; all other `CreateChallengeOptions` fields are optional.
     * Required to use `challengeHandler`; optional if challenges are issued by Sentinel and
     * only `verifyServer` is used.
     */
    createChallengeParameters?: () => Pick<CreateChallengeOptions, 'algorithm' | 'cost'> & Partial<CreateChallengeOptions>;
    /**
     * Algorithm-specific key derivation function used to generate challenge keys.
     * Required to use `challengeHandler` or to verify self-hosted (client-type) payloads;
     * optional if challenges are issued by Sentinel and only `verifyServer` is used.
     */
    deriveKey?: DeriveKeyFunction;
    /**
     * Name of the form field that carries the ALTCHA payload.
     * Defaults to `'altcha'` if not specified.
     */
    fieldName?: string;
    /**
     * HMAC secret used to sign and verify challenge signatures.
     * Optional if `verifyServer` is configured and only Sentinel-issued (server-signed)
     * payloads are verified remotely.
     */
    hmacSignatureSecret?: string;
    /**
     * HMAC secret used to sign keys in deterministic mode.
     */
    hmacKeySignatureSecret?: string;
    /**
     * Cookie configuration for sending the payload via a cookie.
     * The `name` field is required; all other `SetCookieOptions` fields are optional.
     */
    setCookie?: RequireField<SetCookieOptions, 'name'>;
    /**
     * Store implementation for tracking used challenges and preventing replay attacks.
     */
    store?: Store;
    /**
     * When set, Sentinel-issued (server-signed) payloads are verified remotely via
     * `POST /v1/verify/signature` instead of locally with `hmacSignatureSecret`.
     */
    verifyServer?: AltchaVerifyServerOptions;
}
export interface AltchaMiddlewareOptions {
    throwOnFailure?: boolean;
}
export interface AltchaResult {
    error: string | null;
    payload: Payload | ServerSignaturePayload | null;
    verification: VerifySolutionResult | VerifyServerResult | null;
}
export type RequireField<T, K extends keyof T> = Omit<T, K> & Required<Pick<T, K>>;
export interface Store {
    get: (key: string) => Promise<unknown> | unknown;
    set: (key: string, value: boolean) => Promise<unknown> | unknown;
}