/*
    This file is part of web3.js.

    web3.js is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    web3.js is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with web3.js.  If not, see <http://www.gnu.org/licenses/>.
*/
/** 
 * @file iban.js
 * @author Marek Kotewicz <marek@ethdev.com>
 * @date 2015
 */

var BigNumber = require('bignumber.js');

var padLeft = function (string, bytes) {
    var result = string;
    while (result.length < bytes * 2) {
        result = '00' + result;
    }
    return result;
};

/**
 * Prepare an IBAN for mod 97 computation by moving the first 4 chars to the end and transforming the letters to
 * numbers (A = 10, B = 11, ..., Z = 35), as specified in ISO13616.
 *
 * @method iso13616Prepare
 * @param {String} iban the IBAN
 * @returns {String} the prepared IBAN
 */
var iso13616Prepare = function (iban) {
    var A = 'A'.charCodeAt(0);
    var Z = 'Z'.charCodeAt(0);

    iban = iban.toUpperCase();
    iban = iban.substr(4) + iban.substr(0,4);

    return iban.split('').map(function(n){
        var code = n.charCodeAt(0);
        if (code >= A && code <= Z){
            // A = 10, B = 11, ... Z = 35
            return code - A + 10;
        } else {
            return n;
        }
    }).join('');
};

/**
 * Calculates the MOD 97 10 of the passed IBAN as specified in ISO7064.
 *
 * @method mod9710
 * @param {String} iban
 * @returns {Number}
 */
var mod9710 = function (iban) {
    var remainder = iban,
        block;

    while (remainder.length > 2){
        block = remainder.slice(0, 9);
        remainder = parseInt(block, 10) % 97 + remainder.slice(block.length);
    }

    return parseInt(remainder, 10) % 97;
};

/**
 * This prototype should be used to create iban object from iban correct string
 *
 * @param {String} iban
 */
var Iban = function (iban) {
    this._iban = iban;
};

/**
 * This method should be used to create iban object from ethereum address
 *
 * @method fromAddress
 * @param {String} address
 * @return {Iban} the IBAN object
 */
Iban.fromAddress = function (address) {
    var asBn = new BigNumber(address, 16);
    var base36 = asBn.toString(36);
    var padded = padLeft(base36, 15);
    return Iban.fromBban(padded.toUpperCase());
};

/**
 * Convert the passed BBAN to an IBAN for this country specification.
 * Please note that <i>"generation of the IBAN shall be the exclusive responsibility of the bank/branch servicing the account"</i>.
 * This method implements the preferred algorithm described in http://en.wikipedia.org/wiki/International_Bank_Account_Number#Generating_IBAN_check_digits
 *
 * @method fromBban
 * @param {String} bban the BBAN to convert to IBAN
 * @returns {Iban} the IBAN object
 */
Iban.fromBban = function (bban) {
    var countryCode = 'XE';

    var remainder = mod9710(iso13616Prepare(countryCode + '00' + bban));
    var checkDigit = ('0' + (98 - remainder)).slice(-2);

    return new Iban(countryCode + checkDigit + bban);
};

/**
 * Should be used to create IBAN object for given institution and identifier
 *
 * @method createIndirect
 * @param {Object} options, required options are "institution" and "identifier"
 * @return {Iban} the IBAN object
 */
Iban.createIndirect = function (options) {
    return Iban.fromBban('ETH' + options.institution + options.identifier);
};

/**
 * Thos method should be used to check if given string is valid iban object
 *
 * @method isValid
 * @param {String} iban string
 * @return {Boolean} true if it is valid IBAN
 */
Iban.isValid = function (iban) {
    var i = new Iban(iban);
    return i.isValid();
};

/**
 * Should be called to check if iban is correct
 *
 * @method isValid
 * @returns {Boolean} true if it is, otherwise false
 */
Iban.prototype.isValid = function () {
    return /^XE[0-9]{2}(ETH[0-9A-Z]{13}|[0-9A-Z]{30,31})$/.test(this._iban) &&
        mod9710(iso13616Prepare(this._iban)) === 1;
};

/**
 * Should be called to check if iban number is direct
 *
 * @method isDirect
 * @returns {Boolean} true if it is, otherwise false
 */
Iban.prototype.isDirect = function () {
    return this._iban.length === 34 || this._iban.length === 35;
};

/**
 * Should be called to check if iban number if indirect
 *
 * @method isIndirect
 * @returns {Boolean} true if it is, otherwise false
 */
Iban.prototype.isIndirect = function () {
    return this._iban.length === 20;
};

/**
 * Should be called to get iban checksum
 * Uses the mod-97-10 checksumming protocol (ISO/IEC 7064:2003)
 *
 * @method checksum
 * @returns {String} checksum
 */
Iban.prototype.checksum = function () {
    return this._iban.substr(2, 2);
};

/**
 * Should be called to get institution identifier
 * eg. XREG
 *
 * @method institution
 * @returns {String} institution identifier
 */
Iban.prototype.institution = function () {
    return this.isIndirect() ? this._iban.substr(7, 4) : '';
};

/**
 * Should be called to get client identifier within institution
 * eg. GAVOFYORK
 *
 * @method client
 * @returns {String} client identifier
 */
Iban.prototype.client = function () {
    return this.isIndirect() ? this._iban.substr(11) : '';
};

/**
 * Should be called to get client direct address
 *
 * @method address
 * @returns {String} client direct address
 */
Iban.prototype.address = function () {
    if (this.isDirect()) {
        var base36 = this._iban.substr(4);
        var asBn = new BigNumber(base36, 36);
        return padLeft(asBn.toString(16), 20);
    } 

    return '';
};

Iban.prototype.toString = function () {
    return this._iban;
};

module.exports = Iban;