declare module "next-safe" {
    function nextSafe(options: NextSafeConfig | undefined): Header[];
}

/**
 * A CSP Directive Poroperty
 */
declare type CSPDirective = string | string[];

/**
 * A CSP Config
 */
declare type CSPConfig = {
    'base-uri'?: CSPDirective;
    'child-src'?: CSPDirective;
    'connect-src'?: CSPDirective;
    'default-src'?: CSPDirective;
    'font-src'?: CSPDirective;
    'form-action'?: CSPDirective;
    'frame-ancestors'?: CSPDirective;
    'frame-src'?: CSPDirective;
    'img-src'?: CSPDirective;
    'manifest-src'?: CSPDirective;
    'media-src'?: CSPDirective;
    'object-src'?: CSPDirective;
    'prefetch-src'?: CSPDirective;
    'script-src'?: CSPDirective;
    'style-src'?: CSPDirective;
    'worker-src'?: CSPDirective;
    'block-all-mixed-content'?: CSPDirective;
    'plugin-types'?: CSPDirective;
    'navigate-to'?: CSPDirective;
    'require-sri-for'?: CSPDirective;
    'require-trusted-types-for'?: CSPDirective;
    'sandbox'?: CSPDirective;
    'script-src-attr'?: CSPDirective;
    'script-src-elem'?: CSPDirective;
    'style-src-attr'?: CSPDirective;
    'style-src-elem'?: CSPDirective;
    'trusted-types'?: CSPDirective;
    'upgrade-insecure-requests'?: CSPDirective;
    'report-to'?: CSPDirective;
    'report-uri'?: CSPDirective;
    mergeDefaultDirectives?: boolean;
    reportOnly?: boolean;
};

/**
 * Response header key-value pair
 */
declare type Header = {
    key: string;
    value: string;
};

declare type HeaderConfig = string | false;

declare type PermPolicyDirectiveList = 'experimental' | 'legacy' | 'proposed' | 'standard';

/**
 * nextSafe's primary config object
 */
declare type NextSafeConfig = {
    contentTypeOptions?: HeaderConfig;
    contentSecurityPolicy?: CSPConfig | false;
    frameOptions?: HeaderConfig;
    permissionsPolicy?: {
        [key: string]: string | false;
    } | false;
    permissionsPolicyDirectiveSupport?: PermPolicyDirectiveList[];
    isDev?: boolean;
    referrerPolicy?: HeaderConfig;
    xssProtection?: HeaderConfig;
};

declare function makeHeaderObj(key: string, value: string | false, defaultValue: string): Header;