"use strict";

// http://werxltd.com/wp/2010/05/13/javascript-implementation-of-javas-string-hashcode-method/
// https://github.com/threepointone/glamor/blob/master/src/hash.js
// module.exports = function fliphash(str) {
//   var hash = 0, len = str.length
//   if (len == 0) return 0
//   for (i = 0; i < len; i++) {
//     char = str.charCodeAt(i)
//     hash = ((hash << 5) - hash) + char
//     hash = hash & hash // Convert to 32bit integer
//   }
//   return hash
// }
// murmurhash2 via https://gist.github.com/raycmorgan/588423
module.exports = function doHash(str, seed = '') {
  let m = 0x5bd1e995;
  let r = 24;
  let h = seed ^ str.length;
  let length = str.length;
  let currentIndex = 0;

  while (length >= 4) {
    let k = UInt32(str, currentIndex);
    k = Umul32(k, m);
    k ^= k >>> r;
    k = Umul32(k, m);
    h = Umul32(h, m);
    h ^= k;
    currentIndex += 4;
    length -= 4;
  }

  switch (length) {
    case 3:
      h ^= UInt16(str, currentIndex);
      h ^= str.charCodeAt(currentIndex + 2) << 16;
      h = Umul32(h, m);
      break;

    case 2:
      h ^= UInt16(str, currentIndex);
      h = Umul32(h, m);
      break;

    case 1:
      h ^= str.charCodeAt(currentIndex);
      h = Umul32(h, m);
      break;
  }

  h ^= h >>> 13;
  h = Umul32(h, m);
  h ^= h >>> 15;
  return h >>> 0;
};

function UInt32(str, pos) {
  return str.charCodeAt(pos++) + (str.charCodeAt(pos++) << 8) + (str.charCodeAt(pos++) << 16) + (str.charCodeAt(pos) << 24);
}

function UInt16(str, pos) {
  return str.charCodeAt(pos++) + (str.charCodeAt(pos++) << 8);
}

function Umul32(n, m) {
  n = n | 0;
  m = m | 0;
  let nlo = n & 0xffff;
  let nhi = n >>> 16;
  let res = nlo * m + ((nhi * m & 0xffff) << 16) | 0;
  return res;
}