/**
 * 零依赖 MD5 实现（不依赖 crypt/charenc 等 npm 包）
 * 适配微信小程序 / App / H5，避免 npm 传递依赖在小程序端解析失败。
 * 用法：import md5 from '@/utils/md5.js'  ->  md5('abc')
 */
function safeAdd(x, y) {
  const lsw = (x & 0xffff) + (y & 0xffff)
  const msw = (x >> 16) + (y >> 16) + (lsw >> 16)
  return (msw << 16) | (lsw & 0xffff)
}

function rotl(num, cnt) {
  return (num << cnt) | (num >>> (32 - cnt))
}

function cmn(q, a, b, x, s, t) {
  return safeAdd(rotl(safeAdd(safeAdd(a, q), safeAdd(x, t)), 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 coreMd5(x, len) {
  x[len >> 5] |= 0x80 << len % 32
  x[(((len + 64) >>> 9) << 4) + 14] = len

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

  for (let i = 0; i < x.length; i += 16) {
    const olda = a
    const oldb = b
    const oldc = c
    const oldd = d

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

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

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

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

    a = safeAdd(a, olda)
    b = safeAdd(b, oldb)
    c = safeAdd(c, oldc)
    d = safeAdd(d, oldd)
  }
  return [a, b, c, d]
}

function binlToRstr(input) {
  let output = ''
  for (let i = 0; i < input.length * 32; i += 8) {
    output += String.fromCharCode((input[i >> 5] >>> i % 32) & 0xff)
  }
  return output
}

function rstrToBinl(input) {
  const output = []
  for (let i = 0; i < input.length * 8; i += 8) {
    output[i >> 5] |= (input.charCodeAt(i / 8) & 0xff) << i % 32
  }
  return output
}

function rstrMd5(s) {
  return binlToRstr(coreMd5(rstrToBinl(s), s.length * 8))
}

function rstrToHex(input) {
  const hexTab = '0123456789abcdef'
  let output = ''
  for (let i = 0; i < input.length; i++) {
    const x = input.charCodeAt(i)
    output += hexTab.charAt((x >>> 4) & 0x0f) + hexTab.charAt(x & 0x0f)
  }
  return output
}

function strToUtf8(input) {
  return unescape(encodeURIComponent(input))
}

export default function md5(str) {
  return rstrToHex(rstrMd5(strToUtf8(String(str))))
}