util.js

// Copyright 2022 DeepL SE (https://www.deepl.com)
// Use of this source code is governed by an MIT
// license that can be found in the LICENSE file.

function cleanup(dictionary, lifetimeMs, callback) {
  const now = new Date();
  // Remove all objects with a used timestamp older than specified lifetime
  dictionary.forEach((object, id) => {
    if (now - object.used > lifetimeMs) {
      callback(object, id);
      dictionary.delete(id);
    }
  });
}

function scheduleCleanup(map, callback) {
  // Schedules a repeated check for objects older than 10min in given map, callback is called
  // for each expired object
  setInterval(() => cleanup(map, 600000, callback), 1000);
}

class HttpError extends Error {
  constructor(message, status, detail) {
    super(message);
    this.status_internal = status;
    this.detail = detail;
  }

  status() {
    return this.status_internal || 400;
  }

  body() {
    const result = {};
    if (this.message) { result.message = this.message; }
    if (this.detail) { result.detail = this.detail; }
    return result;
  }
}

// This is a simplified implementation of this conversion that won't work for all
// BCP-47 codes, but all we currently use at DeepL.
// Before further complicating this implementation, it might make sense to switch
// to a library.
function convertToBcp47(langCode) {
  const tokens = langCode.split('-');
  return tokens.map((token, index) => {
    if (index === 0) return token.toLowerCase();
    // Script subtags are exactly 4 alphabetic characters and use title case (e.g. Hans, Hant)
    if (token.length === 4 && /^[a-zA-Z]{4}$/.test(token)) {
      return token.charAt(0).toUpperCase() + token.slice(1).toLowerCase();
    }
    return token.toUpperCase();
  }).join('-');
}

/**
 * Given any two objects with sourceLang and targetLang parameters, checks if they match.
 */
function langPairMatches(dictL, dictR) {
  return dictL.sourceLang.toLowerCase() === dictR.sourceLang.toLowerCase()
      && dictL.targetLang.toLowerCase() === dictR.targetLang.toLowerCase();
}

/**
 * Generates a random hexadecimal string of the specified length.
 */
function generateRandomHexString(length) {
  const hex = '0123456789ABCDEF';
  let output = '';
  for (let i = 0; i < length; i += 1) {
    output += hex.charAt(Math.floor(Math.random() * 16));
  }
  return output;
}

// Mirrors uuid v8's `validate()`: any RFC 4122 v1–v5 UUID, or the nil UUID.
const UUID_RE = /^(?:[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}|00000000-0000-0000-0000-000000000000)$/i;

function isValidUuid(s) {
  return typeof s === 'string' && UUID_RE.test(s);
}

module.exports = {
  convertToBcp47, langPairMatches, scheduleCleanup, HttpError, generateRandomHexString, isValidUuid,
};