const safeAdd = (x, y) => {
  const lsw = (x & 0xffff) + (y & 0xffff)
  const msw = (x >> 16) + (y >> 16) + (lsw >> 16)
  return (msw << 16) | (lsw & 0xffff)
}

const bitRotateLeft = (value, count) => (value << count) | (value >>> (32 - count))
const common = (q, a, b, x, s, t) => safeAdd(bitRotateLeft(safeAdd(safeAdd(a, q), safeAdd(x, t)), s), b)
const ff = (a, b, c, d, x, s, t) => common((b & c) | ((~b) & d), a, b, x, s, t)
const gg = (a, b, c, d, x, s, t) => common((b & d) | (c & (~d)), a, b, x, s, t)
const hh = (a, b, c, d, x, s, t) => common(b ^ c ^ d, a, b, x, s, t)
const ii = (a, b, c, d, x, s, t) => common(c ^ (b | (~d)), a, b, x, s, t)

const toWords = (value) => {
  const words = []
  for (let index = 0; index < value.length * 8; index += 8) {
    words[index >> 5] |= (value.charCodeAt(index / 8) & 0xff) << (index % 32)
  }
  return words
}

const toWordsFromBytes = (bytes) => {
  const words = []
  for (let index = 0; index < bytes.length; index += 1) {
    words[index >> 2] |= bytes[index] << ((index % 4) * 8)
  }
  return words
}

const toHex = (words) => {
  const alphabet = '0123456789abcdef'
  let output = ''
  for (let index = 0; index < words.length * 4; index += 1) {
    output += alphabet.charAt((words[index >> 2] >> ((index % 4) * 8 + 4)) & 0x0f)
    output += alphabet.charAt((words[index >> 2] >> ((index % 4) * 8)) & 0x0f)
  }
  return output
}

const coreMd5 = (words, bitLength) => {
  words[bitLength >> 5] |= 0x80 << (bitLength % 32)
  words[(((bitLength + 64) >>> 9) << 4) + 14] = bitLength

  let a = 1732584193
  let b = -271733879
  let c = -1732584194
  let d = 271733878

  for (let index = 0; index < words.length; index += 16) {
    const oldA = a
    const oldB = b
    const oldC = c
    const oldD = d

    a = ff(a, b, c, d, words[index], 7, -680876936); d = ff(d, a, b, c, words[index + 1], 12, -389564586); c = ff(c, d, a, b, words[index + 2], 17, 606105819); b = ff(b, c, d, a, words[index + 3], 22, -1044525330)
    a = ff(a, b, c, d, words[index + 4], 7, -176418897); d = ff(d, a, b, c, words[index + 5], 12, 1200080426); c = ff(c, d, a, b, words[index + 6], 17, -1473231341); b = ff(b, c, d, a, words[index + 7], 22, -45705983)
    a = ff(a, b, c, d, words[index + 8], 7, 1770035416); d = ff(d, a, b, c, words[index + 9], 12, -1958414417); c = ff(c, d, a, b, words[index + 10], 17, -42063); b = ff(b, c, d, a, words[index + 11], 22, -1990404162)
    a = ff(a, b, c, d, words[index + 12], 7, 1804603682); d = ff(d, a, b, c, words[index + 13], 12, -40341101); c = ff(c, d, a, b, words[index + 14], 17, -1502002290); b = ff(b, c, d, a, words[index + 15], 22, 1236535329)
    a = gg(a, b, c, d, words[index + 1], 5, -165796510); d = gg(d, a, b, c, words[index + 6], 9, -1069501632); c = gg(c, d, a, b, words[index + 11], 14, 643717713); b = gg(b, c, d, a, words[index], 20, -373897302)
    a = gg(a, b, c, d, words[index + 5], 5, -701558691); d = gg(d, a, b, c, words[index + 10], 9, 38016083); c = gg(c, d, a, b, words[index + 15], 14, -660478335); b = gg(b, c, d, a, words[index + 4], 20, -405537848)
    a = gg(a, b, c, d, words[index + 9], 5, 568446438); d = gg(d, a, b, c, words[index + 14], 9, -1019803690); c = gg(c, d, a, b, words[index + 3], 14, -187363961); b = gg(b, c, d, a, words[index + 8], 20, 1163531501)
    a = gg(a, b, c, d, words[index + 13], 5, -1444681467); d = gg(d, a, b, c, words[index + 2], 9, -51403784); c = gg(c, d, a, b, words[index + 7], 14, 1735328473); b = gg(b, c, d, a, words[index + 12], 20, -1926607734)
    a = hh(a, b, c, d, words[index + 5], 4, -378558); d = hh(d, a, b, c, words[index + 8], 11, -2022574463); c = hh(c, d, a, b, words[index + 11], 16, 1839030562); b = hh(b, c, d, a, words[index + 14], 23, -35309556)
    a = hh(a, b, c, d, words[index + 1], 4, -1530992060); d = hh(d, a, b, c, words[index + 4], 11, 1272893353); c = hh(c, d, a, b, words[index + 7], 16, -155497632); b = hh(b, c, d, a, words[index + 10], 23, -1094730640)
    a = hh(a, b, c, d, words[index + 13], 4, 681279174); d = hh(d, a, b, c, words[index], 11, -358537222); c = hh(c, d, a, b, words[index + 3], 16, -722521979); b = hh(b, c, d, a, words[index + 6], 23, 76029189)
    a = hh(a, b, c, d, words[index + 9], 4, -640364487); d = hh(d, a, b, c, words[index + 12], 11, -421815835); c = hh(c, d, a, b, words[index + 15], 16, 530742520); b = hh(b, c, d, a, words[index + 2], 23, -995338651)
    a = ii(a, b, c, d, words[index], 6, -198630844); d = ii(d, a, b, c, words[index + 7], 10, 1126891415); c = ii(c, d, a, b, words[index + 14], 15, -1416354905); b = ii(b, c, d, a, words[index + 5], 21, -57434055)
    a = ii(a, b, c, d, words[index + 12], 6, 1700485571); d = ii(d, a, b, c, words[index + 3], 10, -1894986606); c = ii(c, d, a, b, words[index + 10], 15, -1051523); b = ii(b, c, d, a, words[index + 1], 21, -2054922799)
    a = ii(a, b, c, d, words[index + 8], 6, 1873313359); d = ii(d, a, b, c, words[index + 15], 10, -30611744); c = ii(c, d, a, b, words[index + 6], 15, -1560198380); b = ii(b, c, d, a, words[index + 13], 21, 1309151649)
    a = ii(a, b, c, d, words[index + 4], 6, -145523070); d = ii(d, a, b, c, words[index + 11], 10, -1120210379); c = ii(c, d, a, b, words[index + 2], 15, 718787259); b = ii(b, c, d, a, words[index + 9], 21, -343485551)

    a = safeAdd(a, oldA); b = safeAdd(b, oldB); c = safeAdd(c, oldC); d = safeAdd(d, oldD)
  }
  return [a, b, c, d]
}

export const calcMD5 = (value) => {
  const utf8Value = unescape(encodeURIComponent(String(value)))
  return toHex(coreMd5(toWords(utf8Value), utf8Value.length * 8))
}

export const calcMD5Bytes = (value) => {
  const bytes = value instanceof ArrayBuffer
    ? new Uint8Array(value)
    : ArrayBuffer.isView(value)
      ? new Uint8Array(value.buffer, value.byteOffset, value.byteLength)
      : null
  if (!bytes) throw new TypeError('MD5 字节输入必须是 ArrayBuffer 或 TypedArray')
  if (bytes.length > 0x1fffffff) {
    throw new RangeError('当前 MD5 实现不支持超过 512MB 的单文件')
  }
  return toHex(coreMd5(toWordsFromBytes(bytes), bytes.length * 8))
}