utils.js

let RE2;
let hasRE2 = true;

try {
  RE2 = require('re2');
} catch {
  hasRE2 = false;
}

const SafeRegExp = hasRE2 ? RE2 : RegExp;


/**
 * Return the mime type for the given `str`.
 *
 * @param {String} str
 * @return {String}
 * @api private
 */

exports.type = (string_) => string_.split(/ *; */).shift();

/**
 * Return header field parameters.
 *
 * @param {String} str
 * @return {Object}
 * @api private
 */

exports.params = (value) => {
  const object = {};
  for (const string_ of value.split(/ *; */)) {
    const parts = string_.split(/ *= */);
    const key = parts.shift();
    const value = parts.shift();

    if (key && value) object[key] = value;
  }

  return object;
};

/**
 * Parse Link header fields.
 *
 * @param {String} str
 * @return {Object}
 * @api private
 */

exports.parseLinks = (value) => {
  const object = {};
  for (const string_ of value.split(/ *, */)) {
    const parts = string_.split(/ *; */);
    const url = parts[0].slice(1, -1);
    const rel = parts[1].split(/ *= */)[1].slice(1, -1);
    object[rel] = url;
  }

  return object;
};

/**
 * Strip content related fields from `header`.
 *
 * @param {Object} header
 * @return {Object} header
 * @api private
 */

exports.cleanHeader = (header, changesOrigin) => {
  delete header['content-type'];
  delete header['content-length'];
  delete header['transfer-encoding'];
  delete header.host;
  // secuirty
  if (changesOrigin) {
    delete header.authorization;
    delete header.cookie;
  }

  return header;
};

/**
 * Check if `obj` is an object.
 *
 * @param {Object} object
 * @return {Boolean}
 * @api private
 */
exports.isObject = (object) => {
  return object !== null && typeof object === 'object';
};

/**
 * Object.hasOwn fallback/polyfill.
 *
 * @type {(object: object, property: string) => boolean} object
 * @api private
 */
exports.hasOwn =
  Object.hasOwn ||
  function (object, property) {
    if (object == null) {
      throw new TypeError('Cannot convert undefined or null to object');
    }

    return Object.prototype.hasOwnProperty.call(new Object(object), property);
  };

exports.mixin = (target, source) => {
  for (const key in source) {
    if (exports.hasOwn(source, key)) {
      target[key] = source[key];
    }
  }
};

/**
 * Check if the response is compressed using Gzip or Deflate.
 * @param {Object} res
 * @return {Boolean}
 */

exports.isGzipOrDeflateEncoding = (res) => {
  return new SafeRegExp(/^\s*(?:deflate|gzip)\s*$/).test(res.headers['content-encoding']);
};

/**
 * Check if the response is compressed using Brotli.
 * @param {Object} res
 * @return {Boolean}
 */

exports.isBrotliEncoding = (res) => {
  return new SafeRegExp(/^\s*(?:br)\s*$/).test(res.headers['content-encoding']);
};