@owstack/bch-lib/lib/transaction/signature.js

A Javascript library to build bitcoin cash and blockchain-based applications.

'use strict';

var owsCommon = require('@owstack/ows-common');
var keyLib = require('@owstack/key-lib');
var Buffer = owsCommon.deps.Buffer;
var BufferUtil = owsCommon.buffer;
var errors = owsCommon.errors;
var inherits = require('inherits');
var JSUtil = owsCommon.util.js;
var PublicKey = keyLib.PublicKey;
var Signature = keyLib.crypto.Signature;
var lodash = owsCommon.deps.lodash;
var $ = owsCommon.util.preconditions;

/**
 * @desc
 * Wrapper around Signature with fields related to signing a transaction specifically
 *
 * @param {Object|string|TransactionSignature} arg
 * @constructor
 */
function TransactionSignature(arg) {
  if (!(this instanceof TransactionSignature)) {
    return new TransactionSignature(arg);
  }
  if (arg instanceof TransactionSignature) {
    return arg;
  }
  if (lodash.isObject(arg)) {
    return this._fromObject(arg);
  }
  throw new errors.InvalidArgument('TransactionSignatures must be instantiated from an object');
}
inherits(TransactionSignature, Signature);

TransactionSignature.prototype._fromObject = function(arg) {
  this._checkObjectArgs(arg);
  this.publicKey = new PublicKey(arg.publicKey);
  this.prevTxId = BufferUtil.isBuffer(arg.prevTxId) ? arg.prevTxId : new Buffer(arg.prevTxId, 'hex');
  this.outputIndex = arg.outputIndex;
  this.inputIndex = arg.inputIndex;
  this.signature = (arg.signature instanceof Signature) ? arg.signature :
                     BufferUtil.isBuffer(arg.signature) ? Signature.fromBuffer(arg.signature) :
                     Signature.fromString(arg.signature);
  this.sigtype = arg.sigtype;
  return this;
};

TransactionSignature.prototype._checkObjectArgs = function(arg) {
  $.checkArgument(PublicKey(arg.publicKey), 'publicKey');
  $.checkArgument(!lodash.isUndefined(arg.inputIndex), 'inputIndex');
  $.checkArgument(!lodash.isUndefined(arg.outputIndex), 'outputIndex');
  $.checkState(lodash.isNumber(arg.inputIndex), 'inputIndex must be a number');
  $.checkState(lodash.isNumber(arg.outputIndex), 'outputIndex must be a number');
  $.checkArgument(arg.signature, 'signature');
  $.checkArgument(arg.prevTxId, 'prevTxId');
  $.checkState(arg.signature instanceof Signature ||
               BufferUtil.isBuffer(arg.signature) ||
               JSUtil.isHexa(arg.signature), 'signature must be a buffer or hexa value');
  $.checkState(BufferUtil.isBuffer(arg.prevTxId) ||
               JSUtil.isHexa(arg.prevTxId), 'prevTxId must be a buffer or hexa value');
  $.checkArgument(arg.sigtype, 'sigtype');
  $.checkState(lodash.isNumber(arg.sigtype), 'sigtype must be a number');
};

/**
 * Serializes a transaction to a plain JS object
 * @return {Object}
 */
TransactionSignature.prototype.toObject = TransactionSignature.prototype.toJSON = function toObject() {
  return {
    publicKey: this.publicKey.toString(),
    prevTxId: this.prevTxId.toString('hex'),
    outputIndex: this.outputIndex,
    inputIndex: this.inputIndex,
    signature: this.signature.toString(),
    sigtype: this.sigtype
  };
};

/**
 * Builds a TransactionSignature from an object
 * @param {Object} object
 * @return {TransactionSignature}
 */
TransactionSignature.fromObject = function(object) {
  $.checkArgument(object);
  return new TransactionSignature(object);
};

module.exports = TransactionSignature;