const ALPHABET = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
const ALPHABET_MAP = ALPHABET.split('').reduce((map:any, c, i) => {
  map[c] = i
  return map
}, {})


export default {
  encode(buffer: Uint8Array): string {

    if (!buffer.length) return ''

    const digits = [0]

    for (let i = 0; i < buffer.length; i++) {

      for (let j = 0; j < digits.length; j++) {
        digits[j] <<= 8
      }

      digits[0] += buffer[i]
      let carry = 0

      for (let k = 0; k < digits.length; k++) {
        digits[k] += carry
        carry = (digits[k] / 58) | 0
        digits[k] %= 58
      }

      while (carry) {
        digits.push(carry % 58)
        carry = (carry / 58) | 0
      }

    }

    for (let i = 0; buffer[i] === 0 && i < buffer.length - 1; i++) {
      digits.push(0)
    }

    return digits.reverse().map(function (digit) {
      return ALPHABET[digit]
    }).join('')

  },

  decode(string: string): Uint8Array {

    if (!string.length) return new Uint8Array(0)

    const bytes = [0]

    for (let i = 0; i < string.length; i++) {

      const c = string[i]
      if (!(c in ALPHABET_MAP)) {
        throw new Error(`There is no character "${c}" in the Base58 sequence!`)
      }

      for (let j = 0; j < bytes.length; j++) {
        bytes[j] *= 58
      }

      bytes[0] += ALPHABET_MAP[c]
      let carry = 0

      for (let j = 0; j < bytes.length; j++) {
        bytes[j] += carry
        carry = bytes[j] >> 8
        bytes[j] &= 0xff
      }

      while (carry) {
        bytes.push(carry & 0xff)
        carry >>= 8
      }

    }

    for (let i = 0; string[i] === '1' && i < string.length - 1; i++) {
      bytes.push(0)
    }

    return new Uint8Array(bytes.reverse())

  },

}