function cmn(q, a, b, x, s, t) {
  a = add32(add32(a, q), add32(x, t));
  return add32((a << s) | (a >>> (32 - s)), b);
}

function ff(a, b, c, d, x, s, t) {
  return cmn((b & c) | (~b & d), a, b, x, s, t);
}

function gg(a, b, c, d, x, s, t) {
  return cmn((b & d) | (c & ~d), a, b, x, s, t);
}

function hh(a, b, c, d, x, s, t) {
  return cmn(b ^ c ^ d, a, b, x, s, t);
}

function ii(a, b, c, d, x, s, t) {
  return cmn(c ^ (b | ~d), a, b, x, s, t);
}

function md5cycle(state, x) {
  let [a, b, c, d] = state;

  a = ff(a, b, c, d, x[0], 7, -680876936);
  d = ff(d, a, b, c, x[1], 12, -389564586);
  c = ff(c, d, a, b, x[2], 17, 606105819);
  b = ff(b, c, d, a, x[3], 22, -1044525330);
  a = ff(a, b, c, d, x[4], 7, -176418897);
  d = ff(d, a, b, c, x[5], 12, 1200080426);
  c = ff(c, d, a, b, x[6], 17, -1473231341);
  b = ff(b, c, d, a, x[7], 22, -45705983);
  a = ff(a, b, c, d, x[8], 7, 1770035416);
  d = ff(d, a, b, c, x[9], 12, -1958414417);
  c = ff(c, d, a, b, x[10], 17, -42063);
  b = ff(b, c, d, a, x[11], 22, -1990404162);
  a = ff(a, b, c, d, x[12], 7, 1804603682);
  d = ff(d, a, b, c, x[13], 12, -40341101);
  c = ff(c, d, a, b, x[14], 17, -1502002290);
  b = ff(b, c, d, a, x[15], 22, 1236535329);

  a = gg(a, b, c, d, x[1], 5, -165796510);
  d = gg(d, a, b, c, x[6], 9, -1069501632);
  c = gg(c, d, a, b, x[11], 14, 643717713);
  b = gg(b, c, d, a, x[0], 20, -373897302);
  a = gg(a, b, c, d, x[5], 5, -701558691);
  d = gg(d, a, b, c, x[10], 9, 38016083);
  c = gg(c, d, a, b, x[15], 14, -660478335);
  b = gg(b, c, d, a, x[4], 20, -405537848);
  a = gg(a, b, c, d, x[9], 5, 568446438);
  d = gg(d, a, b, c, x[14], 9, -1019803690);
  c = gg(c, d, a, b, x[3], 14, -187363961);
  b = gg(b, c, d, a, x[8], 20, 1163531501);
  a = gg(a, b, c, d, x[13], 5, -1444681467);
  d = gg(d, a, b, c, x[2], 9, -51403784);
  c = gg(c, d, a, b, x[7], 14, 1735328473);
  b = gg(b, c, d, a, x[12], 20, -1926607734);

  a = hh(a, b, c, d, x[5], 4, -378558);
  d = hh(d, a, b, c, x[8], 11, -2022574463);
  c = hh(c, d, a, b, x[11], 16, 1839030562);
  b = hh(b, c, d, a, x[14], 23, -35309556);
  a = hh(a, b, c, d, x[1], 4, -1530992060);
  d = hh(d, a, b, c, x[4], 11, 1272893353);
  c = hh(c, d, a, b, x[7], 16, -155497632);
  b = hh(b, c, d, a, x[10], 23, -1094730640);
  a = hh(a, b, c, d, x[13], 4, 681279174);
  d = hh(d, a, b, c, x[0], 11, -358537222);
  c = hh(c, d, a, b, x[3], 16, -722521979);
  b = hh(b, c, d, a, x[6], 23, 76029189);
  a = hh(a, b, c, d, x[9], 4, -640364487);
  d = hh(d, a, b, c, x[12], 11, -421815835);
  c = hh(c, d, a, b, x[15], 16, 530742520);
  b = hh(b, c, d, a, x[2], 23, -995338651);

  a = ii(a, b, c, d, x[0], 6, -198630844);
  d = ii(d, a, b, c, x[7], 10, 1126891415);
  c = ii(c, d, a, b, x[14], 15, -1416354905);
  b = ii(b, c, d, a, x[5], 21, -57434055);
  a = ii(a, b, c, d, x[12], 6, 1700485571);
  d = ii(d, a, b, c, x[3], 10, -1894986606);
  c = ii(c, d, a, b, x[10], 15, -1051523);
  b = ii(b, c, d, a, x[1], 21, -2054922799);
  a = ii(a, b, c, d, x[8], 6, 1873313359);
  d = ii(d, a, b, c, x[15], 10, -30611744);
  c = ii(c, d, a, b, x[6], 15, -1560198380);
  b = ii(b, c, d, a, x[13], 21, 1309151649);
  a = ii(a, b, c, d, x[4], 6, -145523070);
  d = ii(d, a, b, c, x[11], 10, -1120210379);
  c = ii(c, d, a, b, x[2], 15, 718787259);
  b = ii(b, c, d, a, x[9], 21, -343485551);

  state[0] = add32(a, state[0]);
  state[1] = add32(b, state[1]);
  state[2] = add32(c, state[2]);
  state[3] = add32(d, state[3]);
}

function md5blk(s) {
  const blocks = [];
  for (let i = 0; i < 64; i += 4) {
    blocks[i >> 2] =
      s.charCodeAt(i) +
      (s.charCodeAt(i + 1) << 8) +
      (s.charCodeAt(i + 2) << 16) +
      (s.charCodeAt(i + 3) << 24);
  }
  return blocks;
}

function md5blkTail(s, length) {
  const blocks = Array(16).fill(0);
  let i = 0;
  for (; i < length; i++) {
    blocks[i >> 2] |= s.charCodeAt(i) << ((i % 4) << 3);
  }
  blocks[i >> 2] |= 0x80 << ((i % 4) << 3);
  blocks[14] = length * 8;
  return blocks;
}

function md51(str) {
  let n = str.length;
  let state = [1732584193, -271733879, -1732584194, 271733878];
  let i;

  for (i = 64; i <= n; i += 64) {
    md5cycle(state, md5blk(str.substring(i - 64, i)));
  }

  const remaining = str.substring(i - 64);
  md5cycle(state, md5blkTail(remaining, remaining.length));

  return state;
}

function rhex(n) {
  const hexChr = '0123456789abcdef';
  let s = '';
  for (let j = 0; j < 4; j++) {
    s +=
      hexChr.charAt((n >> (j * 8 + 4)) & 0x0f) +
      hexChr.charAt((n >> (j * 8)) & 0x0f);
  }
  return s;
}

function hex(x) {
  for (let i = 0; i < x.length; i++) {
    x[i] = rhex(x[i]);
  }
  return x.join('');
}

function add32(a, b) {
  return (a + b) & 0xffffffff;
}

export function md5(str) {
  return hex(md51(str));
}