index.js

var hex = require('convert-hex')

// For simplicity we redefine it, as the default uses lowercase
var BASE36_ALPHABET = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
var bs36 = require('base-x')(BASE36_ALPHABET)

var ICAP = {}

ICAP.decodeBBAN = function (bban) {
  var length = bban.length
  if (length === 30 || length === 31) {
    var tmp = hex.bytesToHex(bs36.decode(bban))

    // FIXME: horrible padding code
    while (tmp.length < 40) {
      tmp = '0' + tmp
    }

    var extraZeroes = tmp.length - 40
    if (extraZeroes > 0) {
      var zeroes = tmp.slice(0, extraZeroes)
      for (var i = 0; i < extraZeroes; i++) {
        if (zeroes[i] !== '0') throw new Error('Not a valid Ethereum BBAN')
      }
      tmp = tmp.slice(extraZeroes)
    }

    return '0x' + tmp
  } else if (length === 16) {
    return {
      asset: bban.slice(0, 3),
      institution: bban.slice(3, 7),
      client: bban.slice(7, 16)
    }
  } else {
    throw new Error('Not a valid Ethereum BBAN')
  }
}

ICAP.encodeBBAN = function (bban) {
  if (typeof bban === 'object') {
    if (bban.asset.length !== 3 ||
        bban.institution.length !== 4 ||
        bban.client.length !== 9) {
      throw new Error('Invalid \'indirect\' Ethereum BBAN')
    }
    return [ bban.asset, bban.institution, bban.client ].join('').toUpperCase()
  } else if ((bban.length === 42) && (bban[0] === '0') && (bban[1] === 'x')) {
    // Workaround for base-x, see https://github.com/cryptocoinjs/base-x/issues/18
    if ((bban[2] === '0') && (bban[3] === '0')) {
      bban = '0x' + bban.slice(4)
    }

    return bs36.encode(hex.hexToBytes(bban))
  } else {
    throw new Error('Not a valid input for Ethereum BBAN')
  }
}

// ISO13616 reordering and letter translation
// NOTE: we assume input is uppercase only
// based off code from iban.js
function prepare (iban) {
  // move front to the back
  iban = iban.slice(4) + iban.slice(0, 4)

  // translate letters to numbers
  return iban.split('').map(function (n) {
    var code = n.charCodeAt(0)
    // 65 == A, 90 == Z in ASCII
    if (code >= 65 && code <= 90) {
      // A = 10, B = 11, ... Z = 35
      return code - 65 + 10
    } else {
      return n
    }
  }).join('')
}

// Calculate ISO7064 mod 97-10
// NOTE: assumes all numeric input string
function mod9710 (input) {
  var m = 0
  for (var i = 0; i < input.length; i++) {
    m *= 10
    m += input.charCodeAt(i) - 48 // parseInt()
    m %= 97
  }
  return m
}

ICAP.encode = function (bban, print) {
  bban = ICAP.encodeBBAN(bban)

  var checksum = 98 - mod9710(prepare('XE00' + bban))

  // format into 2 digits
  checksum = ('0' + checksum).slice(-2)

  var iban = 'XE' + checksum + bban
  if (print === true) {
    // split a group of 4 chars with spaces
    iban = iban.replace(/(.{4})/g, '$1 ')
  }

  return iban
}

ICAP.decode = function (iban, novalidity) {
  // change from 'print format' to 'electronic format', e.g. remove spaces
  iban = iban.replace(/\ /g, '')

  // check for validity
  if (!novalidity) {
    if (iban.slice(0, 2) !== 'XE') {
      throw new Error('Not in ICAP format')
    }

    if (mod9710(prepare(iban)) !== 1) {
      throw new Error('Invalid checksum in IBAN')
    }
  }

  return ICAP.decodeBBAN(iban.slice(4, 35))
}

/*
 * Convert Ethereum address to ICAP
 * @method fromAddress
 * @param {String} address Address as a hex string.
 * @param {bool} nonstd Accept address which will result in non-standard IBAN
 * @returns {String}
 */
ICAP.fromAddress = function (address, print, nonstd) {
  var ret = ICAP.encode(address, print)

  if ((ret.replace(' ', '').length !== 34) && (nonstd !== true)) {
    throw new Error('Supplied address will result in invalid an IBAN')
  }

  return ret
}

/*
 * Convert asset into ICAP
 * @method fromAsset
 * @param {Object} asset Asset object, must contain the fields asset, institution and client
 * @returns {String}
 */
ICAP.fromAsset = function (asset, print) {
  return ICAP.encode(asset, print)
}

/*
 * Convert an ICAP into an address
 * @method toAddress
 * @param {String} iban IBAN/ICAP, must have an address encoded
 * @returns {String}
 */
ICAP.toAddress = function (iban) {
  var address = ICAP.decode(iban)
  if (typeof address !== 'string') {
    throw new Error('Not an address-encoded ICAP')
  }
  return address
}

/*
 * Convert an ICAP into an asset
 * @method toAsset
 * @param {String} iban IBAN/ICAP, must have an asset encoded
 * @returns {Object}
 */
ICAP.toAsset = function (iban) {
  var asset = ICAP.decode(iban)
  if (typeof asset !== 'object') {
    throw new Error('Not an asset-encoded ICAP')
  }
  return asset
}

ICAP.isICAP = function (iban) {
  try {
    ICAP.decode(iban)
    return true
  } catch (e) {
    return false
  }
}

ICAP.isAddress = function (iban) {
  try {
    ICAP.toAddress(iban)
    return true
  } catch (e) {
    return false
  }
}

ICAP.isAsset = function (iban) {
  try {
    ICAP.toAsset(iban)
    return true
  } catch (e) {
    return false
  }
}

module.exports = ICAP