var BigInteger = require('./jsbn/jsbn');
var Crypto = require('./crypto-js/crypto');

module.exports = {
  /**
   * Cross-browser compatibility version of Array.isArray.
   */
  isArray: Array.isArray || function(o)
  {
    return Object.prototype.toString.call(o) === '[object Array]';
  },

  /**
   * Create a byte array representing a number with the given length
   */
  numToBytes: function(num,bytes) {
    if (bytes === undefined) bytes = 8;
    if (bytes == 0) return [];
    else return [num % 256].concat(module.exports.numToBytes(Math.floor(num / 256),bytes-1));
  },

  /**
   * Convert a byte array to the number that it represents
   */
  bytesToNum: function(bytes) {
    if (bytes.length == 0) return 0;
    else return bytes[0] + 256 * module.exports.bytesToNum(bytes.slice(1));
  },
  /**
   * Turn an integer into a "var_int".
   *
   * "var_int" is a variable length integer used by Bitcoin's binary format.
   *
   * Returns a byte array.
   */
  numToVarInt: function(num) {
    var m = module.exports;
    if (num < 253) return [num];
    else if (num < 65536) return [253].concat(m.numToBytes(num,2));
    else if (num < 4294967296) return [254].concat(m.numToBytes(num,4));
    else return [253].concat(m.numToBytes(num,8));
  },

  bytesToWords: function (bytes) {
        var words = [];
        for (var i = 0, b = 0; i < bytes.length; i++, b += 8) {
            words[b >>> 5] |= bytes[i] << (24 - b % 32);
        }
        return words;
  },
    
  wordsToBytes: function (words) {
        var bytes = [];
        for (var b = 0; b < words.length * 32; b += 8) {
            bytes.push((words[b >>> 5] >>> (24 - b % 32)) & 0xFF);
        }
        return bytes;
  },

  /**
   * Calculate RIPEMD160(SHA256(data)).
   *
   * Takes an arbitrary byte array as inputs and returns the hash as a byte
   * array.
   */
  sha256ripe160: function (data) {
    return Crypto.RIPEMD160(Crypto.SHA256(data, {asBytes: true}), {asBytes: true});
  },
  error: function(msg) {
    throw new Error(msg);
  }
};