git.squeep.com Git - urlittler/blob - src/slug.js

   1 'use strict';
   2
   3 const common = require('./common');
   4 const { createHash } = require('crypto');
   5
   6 /**
   7  * TODO: base62 would be slightly prettier
   8  * TODO: filter potential horrors
   9  * @param {string} seed
  10  * @param {number} maxLength
  11  */
  12 async function newSlug(seed, maxLength = 86) {
  13   let slug;
  14   if (maxLength > 86) {
  15     maxLength = 86;
  16   }
  17   if (typeof seed !== 'undefined') {
  18     const hash = createHash('sha512');
  19     hash.update(seed);
  20     slug = hash.digest('base64');
  21   } else {
  22     const slugRaw = await common.randomBytesAsync(Math.round(maxLength * 3 / 4));
  23     slug = slugRaw.toString('base64');
  24   }
  25   return slug.slice(0, maxLength).replace('/', '-').replace('+', '.');
  26 }
  27
  28
  29 async function* makeSlugGenerator(seed, initialLength = 5, maxLength = 22) {
  30   let length = initialLength;
  31   let slug = await newSlug(seed, maxLength);
  32   while (true) {
  33     yield slug.slice(0, length);
  34     length++;
  35     if (length > maxLength) {
  36       length = initialLength;
  37       slug = await newSlug(undefined, maxLength); // Hash not suitable, try randomness.
  38     }
  39   }
  40 }
  41
  42 module.exports = {
  43   makeSlugGenerator,
  44   newSlug,
  45 };