/** Ported from Hono */
import { MiddlewareContext, Middleware } from '../types';
export type SecureHeadersVariables = {
    secureHeadersNonce?: string;
};
export type PermissionsPolicyDirective = StandardizedFeatures | ProposedFeatures | ExperimentalFeatures;
/**
 * These features have been declared in a published version of the respective specification.
 */
type StandardizedFeatures = 'accelerometer' | 'ambientLightSensor' | 'attributionReporting' | 'autoplay' | 'battery' | 'bluetooth' | 'camera' | 'chUa' | 'chUaArch' | 'chUaBitness' | 'chUaFullVersion' | 'chUaFullVersionList' | 'chUaMobile' | 'chUaModel' | 'chUaPlatform' | 'chUaPlatformVersion' | 'chUaWow64' | 'computePressure' | 'crossOriginIsolated' | 'directSockets' | 'displayCapture' | 'encryptedMedia' | 'executionWhileNotRendered' | 'executionWhileOutOfViewport' | 'fullscreen' | 'geolocation' | 'gyroscope' | 'hid' | 'identityCredentialsGet' | 'idleDetection' | 'keyboardMap' | 'magnetometer' | 'microphone' | 'midi' | 'navigationOverride' | 'payment' | 'pictureInPicture' | 'publickeyCredentialsGet' | 'screenWakeLock' | 'serial' | 'storageAccess' | 'syncXhr' | 'usb' | 'webShare' | 'windowManagement' | 'xrSpatialTracking';
/**
 * These features have been proposed, but the definitions have not yet been integrated into their respective specs.
 */
type ProposedFeatures = 'clipboardRead' | 'clipboardWrite' | 'gemepad' | 'sharedAutofill' | 'speakerSelection';
/**
 * These features generally have an explainer only, but may be available for experimentation by web developers.
 */
type ExperimentalFeatures = 'allScreensCapture' | 'browsingTopics' | 'capturedSurfaceControl' | 'conversionMeasurement' | 'digitalCredentialsGet' | 'focusWithoutUserActivation' | 'joinAdInterestGroup' | 'localFonts' | 'runAdAuction' | 'smartCard' | 'syncScript' | 'trustTokenRedemption' | 'unload' | 'verticalScroll';
export type ContentSecurityPolicyOptionHandler = (ctx: MiddlewareContext, directive: string) => string;
type ContentSecurityPolicyOptionValue = (string | ContentSecurityPolicyOptionHandler)[];
interface ContentSecurityPolicyOptions {
    defaultSrc?: ContentSecurityPolicyOptionValue;
    baseUri?: ContentSecurityPolicyOptionValue;
    childSrc?: ContentSecurityPolicyOptionValue;
    connectSrc?: ContentSecurityPolicyOptionValue;
    fontSrc?: ContentSecurityPolicyOptionValue;
    formAction?: ContentSecurityPolicyOptionValue;
    frameAncestors?: ContentSecurityPolicyOptionValue;
    frameSrc?: ContentSecurityPolicyOptionValue;
    imgSrc?: ContentSecurityPolicyOptionValue;
    manifestSrc?: ContentSecurityPolicyOptionValue;
    mediaSrc?: ContentSecurityPolicyOptionValue;
    objectSrc?: ContentSecurityPolicyOptionValue;
    reportTo?: string;
    sandbox?: ContentSecurityPolicyOptionValue;
    scriptSrc?: ContentSecurityPolicyOptionValue;
    scriptSrcAttr?: ContentSecurityPolicyOptionValue;
    scriptSrcElem?: ContentSecurityPolicyOptionValue;
    styleSrc?: ContentSecurityPolicyOptionValue;
    styleSrcAttr?: ContentSecurityPolicyOptionValue;
    styleSrcElem?: ContentSecurityPolicyOptionValue;
    upgradeInsecureRequests?: ContentSecurityPolicyOptionValue;
    workerSrc?: ContentSecurityPolicyOptionValue;
}
interface ReportToOptions {
    group: string;
    max_age: number;
    endpoints: ReportToEndpoint[];
}
interface ReportToEndpoint {
    url: string;
}
interface ReportingEndpointOptions {
    name: string;
    url: string;
}
type PermissionsPolicyValue = '*' | 'self' | 'src' | 'none' | string;
type PermissionsPolicyOptions = Partial<Record<PermissionsPolicyDirective, PermissionsPolicyValue[] | boolean>>;
type overridableHeader = boolean | string;
interface SecureHeadersOptions {
    contentSecurityPolicy?: ContentSecurityPolicyOptions;
    contentSecurityPolicyReportOnly?: ContentSecurityPolicyOptions;
    crossOriginEmbedderPolicy?: overridableHeader;
    crossOriginResourcePolicy?: overridableHeader;
    crossOriginOpenerPolicy?: overridableHeader;
    originAgentCluster?: overridableHeader;
    referrerPolicy?: overridableHeader;
    reportingEndpoints?: ReportingEndpointOptions[];
    reportTo?: ReportToOptions[];
    strictTransportSecurity?: overridableHeader;
    xContentTypeOptions?: overridableHeader;
    xDnsPrefetchControl?: overridableHeader;
    xDownloadOptions?: overridableHeader;
    xFrameOptions?: overridableHeader;
    xPermittedCrossDomainPolicies?: overridableHeader;
    xXssProtection?: overridableHeader;
    removePoweredBy?: boolean;
    permissionsPolicy?: PermissionsPolicyOptions;
}
export declare const NONCE: ContentSecurityPolicyOptionHandler;
/**
 * Secure Headers Middleware
 * Ported from Hono @see {@link https://hono.dev/docs/middleware/builtin/secure-headers}
 *
 * @param {Partial<SecureHeadersOptions>} [customOptions] - The options for the secure headers middleware.
 * @param {ContentSecurityPolicyOptions} [customOptions.contentSecurityPolicy] - Settings for the Content-Security-Policy header.
 * @param {ContentSecurityPolicyOptions} [customOptions.contentSecurityPolicyReportOnly] - Settings for the Content-Security-Policy-Report-Only header.
 * @param {overridableHeader} [customOptions.crossOriginEmbedderPolicy=false] - Settings for the Cross-Origin-Embedder-Policy header.
 * @param {overridableHeader} [customOptions.crossOriginResourcePolicy=true] - Settings for the Cross-Origin-Resource-Policy header.
 * @param {overridableHeader} [customOptions.crossOriginOpenerPolicy=true] - Settings for the Cross-Origin-Opener-Policy header.
 * @param {overridableHeader} [customOptions.originAgentCluster=true] - Settings for the Origin-Agent-Cluster header.
 * @param {overridableHeader} [customOptions.referrerPolicy=true] - Settings for the Referrer-Policy header.
 * @param {ReportingEndpointOptions[]} [customOptions.reportingEndpoints] - Settings for the Reporting-Endpoints header.
 * @param {ReportToOptions[]} [customOptions.reportTo] - Settings for the Report-To header.
 * @param {overridableHeader} [customOptions.strictTransportSecurity=true] - Settings for the Strict-Transport-Security header.
 * @param {overridableHeader} [customOptions.xContentTypeOptions=true] - Settings for the X-Content-Type-Options header.
 * @param {overridableHeader} [customOptions.xDnsPrefetchControl=true] - Settings for the X-DNS-Prefetch-Control header.
 * @param {overridableHeader} [customOptions.xDownloadOptions=true] - Settings for the X-Download-Options header.
 * @param {overridableHeader} [customOptions.xFrameOptions=true] - Settings for the X-Frame-Options header.
 * @param {overridableHeader} [customOptions.xPermittedCrossDomainPolicies=true] - Settings for the X-Permitted-Cross-Domain-Policies header.
 * @param {overridableHeader} [customOptions.xXssProtection=true] - Settings for the X-XSS-Protection header.
 * @param {boolean} [customOptions.removePoweredBy=true] - Settings for remove X-Powered-By header.
 * @param {PermissionsPolicyOptions} [customOptions.permissionsPolicy] - Settings for the Permissions-Policy header.
 * @returns {MiddlewareHandler} The middleware handler function.
 *
 * @example
 * ```ts
 * app.use(secureHeaders())
 * ```
 */
export declare const secureHeaders: (customOptions?: SecureHeadersOptions) => Middleware;
export {};