const hexList = []
for (let i = 0; i <= 15; i++) {
  hexList[i] = i.toString(16)
}

export function buildUUID() {
  let uuid = ''
  for (let i = 1; i <= 36; i++) {
    if (i === 9 || i === 14 || i === 19 || i === 24) {
      uuid += '-'
    } else if (i === 15) {
      uuid += 4
    } else if (i === 20) {
      uuid += hexList[(Math.random() * 4) | 8]
    } else {
      uuid += hexList[(Math.random() * 16) | 0]
    }
  }
  return uuid.replace(/-/g, '')
}

let unique = 0
export function buildShortUUID(prefix = '') {
  const time = Date.now()
  const random = Math.floor(Math.random() * 1000000000)
  unique++
  return prefix + '_' + random + unique + String(time)
}

export const uuid = function () {
  const s = []
  const hexDigits = '0123456789abcdef'
  for (let i = 0; i < 36; i++) {
    s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1)
  }
  s[14] = '4'
  s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1)
  const _uuid = s.join('')
  return _uuid
}