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import { RequestResponseInterface } from "../../frameworks/interface.ts";
interface ReferrerPolicyOptions {  policy?: string | string[];}
function getHeaderValueFromOptions (options?: ReferrerPolicyOptions): string {  const DEFAULT_POLICY = 'no-referrer';  const ALLOWED_POLICIES: string[] = [    'no-referrer',    'no-referrer-when-downgrade',    'same-origin',    'origin',    'strict-origin',    'origin-when-cross-origin',    'strict-origin-when-cross-origin',    'unsafe-url',    '',  ];
  options = options || {};
  let policyOption: unknown;  if ('policy' in options) {    policyOption = options.policy;  } else {    policyOption = DEFAULT_POLICY;  }
  const policies: unknown[] = Array.isArray(policyOption) ? policyOption : [policyOption];
  if (policies.length === 0) {    throw new Error('At least one policy must be supplied.');  }
  const policiesSeen: Set<string> = new Set();  policies.forEach((policy) => {    if (typeof policy !== 'string' || ALLOWED_POLICIES.indexOf(policy) === -1) {      const allowedPoliciesErrorList = ALLOWED_POLICIES.map((policy) => {        if (policy.length) {          return `"${policy}"`;        } else {          return 'and the empty string';        }      }).join(', ');      throw new Error(`"${policy}" is not a valid policy. Allowed policies: ${allowedPoliciesErrorList}.`);    }
    if (policiesSeen.has(policy)) {      throw new Error(`"${policy}" specified more than once. No duplicates are allowed.`);    }    policiesSeen.add(policy);  });
  return policies.join(',');}
export default function referrerPolicy (requestResponse: RequestResponseInterface, options?: ReferrerPolicyOptions) {  const headerValue = getHeaderValueFromOptions(options);
  requestResponse.setResponseHeader('Referrer-Policy', headerValue);}