utils.js

const miniget = require('miniget');


/**
 * Extract string inbetween another.
 *
 * @param {string} haystack
 * @param {string} left
 * @param {string} right
 * @returns {string}
 */
exports.between = (haystack, left, right) => {
  let pos;
  if (left instanceof RegExp) {
    const match = haystack.match(left);
    if (!match) { return ''; }
    pos = match.index + match[0].length;
  } else {
    pos = haystack.indexOf(left);
    if (pos === -1) { return ''; }
    pos += left.length;
  }
  haystack = haystack.slice(pos);
  pos = haystack.indexOf(right);
  if (pos === -1) { return ''; }
  haystack = haystack.slice(0, pos);
  return haystack;
};


/**
 * Get a number from an abbreviated number string.
 *
 * @param {string} string
 * @returns {number}
 */
exports.parseAbbreviatedNumber = string => {
  const match = string
    .replace(',', '.')
    .replace(' ', '')
    .match(/([\d,.]+)([MK]?)/);
  if (match) {
    let [, num, multi] = match;
    num = parseFloat(num);
    return Math.round(multi === 'M' ? num * 1000000 :
      multi === 'K' ? num * 1000 : num);
  }
  return null;
};

/**
 * Escape sequences for cutAfterJS
 * @param {string} start the character string the escape sequence
 * @param {string} end the character string to stop the escape seequence
 * @param {undefined|Regex} startPrefix a regex to check against the preceding 10 characters
 */
const ESCAPING_SEQUENZES = [
  // Strings
  { start: '"', end: '"' },
  { start: "'", end: "'" },
  { start: '`', end: '`' },
  // RegeEx
  { start: '/', end: '/', startPrefix: /(^|[[{:;,/])\s?$/ },
];

/**
 * Match begin and end braces of input JS, return only JS
 *
 * @param {string} mixedJson
 * @returns {string}
*/
exports.cutAfterJS = mixedJson => {
  // Define the general open and closing tag
  let open, close;
  if (mixedJson[0] === '[') {
    open = '[';
    close = ']';
  } else if (mixedJson[0] === '{') {
    open = '{';
    close = '}';
  }

  if (!open) {
    throw new Error(`Can't cut unsupported JSON (need to begin with [ or { ) but got: ${mixedJson[0]}`);
  }

  // States if the loop is currently inside an escaped js object
  let isEscapedObject = null;

  // States if the current character is treated as escaped or not
  let isEscaped = false;

  // Current open brackets to be closed
  let counter = 0;

  let i;
  // Go through all characters from the start
  for (i = 0; i < mixedJson.length; i++) {
    // End of current escaped object
    if (!isEscaped && isEscapedObject !== null && mixedJson[i] === isEscapedObject.end) {
      isEscapedObject = null;
      continue;
    // Might be the start of a new escaped object
    } else if (!isEscaped && isEscapedObject === null) {
      for (const escaped of ESCAPING_SEQUENZES) {
        if (mixedJson[i] !== escaped.start) continue;
        // Test startPrefix against last 10 characters
        if (!escaped.startPrefix || mixedJson.substring(i - 10, i).match(escaped.startPrefix)) {
          isEscapedObject = escaped;
          break;
        }
      }
      // Continue if we found a new escaped object
      if (isEscapedObject !== null) {
        continue;
      }
    }

    // Toggle the isEscaped boolean for every backslash
    // Reset for every regular character
    isEscaped = mixedJson[i] === '\\' && !isEscaped;

    if (isEscapedObject !== null) continue;

    if (mixedJson[i] === open) {
      counter++;
    } else if (mixedJson[i] === close) {
      counter--;
    }

    // All brackets have been closed, thus end of JSON is reached
    if (counter === 0) {
      // Return the cut JSON
      return mixedJson.substring(0, i + 1);
    }
  }

  // We ran through the whole string and ended up with an unclosed bracket
  throw Error("Can't cut unsupported JSON (no matching closing bracket found)");
};


/**
 * Checks if there is a playability error.
 *
 * @param {Object} player_response
 * @param {Array.<string>} statuses
 * @param {Error} ErrorType
 * @returns {!Error}
 */
exports.playError = (player_response, statuses, ErrorType = Error) => {
  let playability = player_response && player_response.playabilityStatus;
  if (playability && statuses.includes(playability.status)) {
    return new ErrorType(playability.reason || (playability.messages && playability.messages[0]));
  }
  return null;
};

/**
 * Does a miniget request and calls options.requestCallback if present
 *
 * @param {string} url the request url
 * @param {Object} options an object with optional requestOptions and requestCallback parameters
 * @param {Object} requestOptionsOverwrite overwrite of options.requestOptions
 * @returns {miniget.Stream}
 */
exports.exposedMiniget = (url, options = {}, requestOptionsOverwrite) => {
  const req = miniget(url, requestOptionsOverwrite || options.requestOptions);
  if (typeof options.requestCallback === 'function') options.requestCallback(req);
  return req;
};

/**
 * Temporary helper to help deprecating a few properties.
 *
 * @param {Object} obj
 * @param {string} prop
 * @param {Object} value
 * @param {string} oldPath
 * @param {string} newPath
 */
exports.deprecate = (obj, prop, value, oldPath, newPath) => {
  Object.defineProperty(obj, prop, {
    get: () => {
      console.warn(`\`${oldPath}\` will be removed in a near future release, ` +
        `use \`${newPath}\` instead.`);
      return value;
    },
  });
};


// Check for updates.
const pkg = require('../package.json');
const UPDATE_INTERVAL = 1000 * 60 * 60 * 12;
exports.lastUpdateCheck = 0;
exports.checkForUpdates = () => {
  if (!process.env.YTDL_NO_UPDATE && !pkg.version.startsWith('0.0.0-') &&
    Date.now() - exports.lastUpdateCheck >= UPDATE_INTERVAL) {
    exports.lastUpdateCheck = Date.now();
    return miniget('https://api.github.com/repos/fent/node-ytdl-core/releases/latest', {
      headers: { 'User-Agent': 'ytdl-core' },
    }).text().then(response => {
      if (JSON.parse(response).tag_name !== `v${pkg.version}`) {
        console.warn('\x1b[33mWARNING:\x1B[0m ytdl-core is out of date! Update with "npm install ytdl-core@latest".');
      }
    }, err => {
      console.warn('Error checking for updates:', err.message);
      console.warn('You can disable this check by setting the `YTDL_NO_UPDATE` env variable.');
    });
  }
  return null;
};


/**
 * Gets random IPv6 Address from a block
 *
 * @param {string} ip the IPv6 block in CIDR-Notation
 * @returns {string}
 */
exports.getRandomIPv6 = ip => {
  // Start with a fast Regex-Check
  if (!isIPv6(ip)) throw Error('Invalid IPv6 format');
  // Start by splitting and normalizing addr and mask
  const [rawAddr, rawMask] = ip.split('/');
  let base10Mask = parseInt(rawMask);
  if (!base10Mask || base10Mask > 128 || base10Mask < 24) throw Error('Invalid IPv6 subnet');
  const base10addr = normalizeIP(rawAddr);
  // Get random addr to pad with
  // using Math.random since we're not requiring high level of randomness
  const randomAddr = new Array(8).fill(1).map(() => Math.floor(Math.random() * 0xffff));

  // Merge base10addr with randomAddr
  const mergedAddr = randomAddr.map((randomItem, idx) => {
    // Calculate the amount of static bits
    const staticBits = Math.min(base10Mask, 16);
    // Adjust the bitmask with the staticBits
    base10Mask -= staticBits;
    // Calculate the bitmask
    // lsb makes the calculation way more complicated
    const mask = 0xffff - ((2 ** (16 - staticBits)) - 1);
    // Combine base10addr and random
    return (base10addr[idx] & mask) + (randomItem & (mask ^ 0xffff));
  });
  // Return new addr
  return mergedAddr.map(x => x.toString('16')).join(':');
};


// eslint-disable-next-line max-len
const IPV6_REGEX = /^(([0-9a-f]{1,4}:)(:[0-9a-f]{1,4}){1,6}|([0-9a-f]{1,4}:){1,2}(:[0-9a-f]{1,4}){1,5}|([0-9a-f]{1,4}:){1,3}(:[0-9a-f]{1,4}){1,4}|([0-9a-f]{1,4}:){1,4}(:[0-9a-f]{1,4}){1,3}|([0-9a-f]{1,4}:){1,5}(:[0-9a-f]{1,4}){1,2}|([0-9a-f]{1,4}:){1,6}(:[0-9a-f]{1,4})|([0-9a-f]{1,4}:){1,7}(([0-9a-f]{1,4})|:))\/(1[0-1]\d|12[0-8]|\d{1,2})$/;
/**
 * Quick check for a valid IPv6
 * The Regex only accepts a subset of all IPv6 Addresses
 *
 * @param {string} ip the IPv6 block in CIDR-Notation to test
 * @returns {boolean} true if valid
 */
const isIPv6 = exports.isIPv6 = ip => IPV6_REGEX.test(ip);


/**
 * Normalise an IP Address
 *
 * @param {string} ip the IPv6 Addr
 * @returns {number[]} the 8 parts of the IPv6 as Integers
 */
const normalizeIP = exports.normalizeIP = ip => {
  // Split by fill position
  const parts = ip.split('::').map(x => x.split(':'));
  // Normalize start and end
  const partStart = parts[0] || [];
  const partEnd = parts[1] || [];
  partEnd.reverse();
  // Placeholder for full ip
  const fullIP = new Array(8).fill(0);
  // Fill in start and end parts
  for (let i = 0; i < Math.min(partStart.length, 8); i++) {
    fullIP[i] = parseInt(partStart[i], 16) || 0;
  }
  for (let i = 0; i < Math.min(partEnd.length, 8); i++) {
    fullIP[7 - i] = parseInt(partEnd[i], 16) || 0;
  }
  return fullIP;
};