// These hashes are for algorithmic use cases, such as bucketing in hashtables, where security isn't
// needed and 32 or 64 bits is enough (that is, rare collisions are acceptable). These are way simpler
// than sha1 (and all its deps) or similar, and with a short, clean (base 36 alphanumeric) result.

// A simple, *insecure* 32-bit hash that's short, fast, and has no dependencies.
// Output is always 7 characters.
// Loosely based on the Java version; see
// https://stackoverflow.com/questions/6122571/simple-non-secure-hash-function-for-javascript
const simpleHash = str => {
  let hash = 0;
  for (let i = 0; i < str.length; i++) {
    const char = str.charCodeAt(i);
    hash = (hash << 5) - hash + char;
  }
  // Convert to 32bit unsigned integer in base 36 and pad with "0" to ensure length is 7.
  return (hash >>> 0).toString(36).padStart(7, '0');
};

// An improved alternative:

// cyrb53 (c) 2018 bryc (github.com/bryc). License: Public domain. Attribution appreciated.
// A fast and simple 64-bit (or 53-bit) string hash function with decent collision resistance.
// Largely inspired by MurmurHash2/3, but with a focus on speed/simplicity.
// See https://stackoverflow.com/questions/7616461/generate-a-hash-from-string-in-javascript/52171480#52171480
// https://github.com/bryc/code/blob/master/jshash/experimental/cyrb53.js
const cyrb64 = (str, seed = 0) => {
  let h1 = 0xdeadbeef ^ seed, h2 = 0x41c6ce57 ^ seed;
  for(let i = 0, ch; i < str.length; i++) {
    ch = str.charCodeAt(i);
    h1 = Math.imul(h1 ^ ch, 2654435761);
    h2 = Math.imul(h2 ^ ch, 1597334677);
  }
  h1  = Math.imul(h1 ^ (h1 >>> 16), 2246822507);
  h1 ^= Math.imul(h2 ^ (h2 >>> 13), 3266489909);
  h2  = Math.imul(h2 ^ (h2 >>> 16), 2246822507);
  h2 ^= Math.imul(h1 ^ (h1 >>> 13), 3266489909);
  // For a single 53-bit numeric return value we could return
  // 4294967296 * (2097151 & h2) + (h1 >>> 0);
  // but we instead return the full 64-bit value:
  return [h2>>>0, h1>>>0];
};

// An improved, *insecure* 64-bit hash that's short, fast, and has no dependencies.
// Output is always 14 characters.
const cyrb64Hash =  (str, seed = 0) => {
  const [h2, h1] = cyrb64(str, seed);
  return h2.toString(36).padStart(7, '0') + h1.toString(36).padStart(7, '0');
}