digibyte/lib/asset/transferencoder.js

A pure and powerful JavaScript DigiByte library.

'use strict';

var $ = require('../util/preconditions');
var assetUtils = require('../util/assets');
var BurnPaymentEncoder = require('./burnpaymentencoder');
var PaymentEncoder = require('./paymentencoder');

var TYPE_MASK = 0xf0
var TRANSFER_MASK = 0x10
var BURN_MASK = 0x20
var TRANSFER_OP_CODES = [
  new Buffer([0x10]), // All Hashes in OP_RETURN
  new Buffer([0x11]), // SHA2 in Pay-to-Script-Hash multi-sig output (1 out of 2)
  new Buffer([0x12]), // All Hashes in Pay-to-Script-Hash multi-sig outputs (1 out of 3)
  new Buffer([0x13]), // Low security transaction no SHA2 for torrent data. SHA1 is always inside OP_RETURN in this case.
  new Buffer([0x14]), // Low security transaction no SHA2 for torrent data. SHA1 is always inside OP_RETURN in this case. also no rules inside the metadata (if there are any they will be in ignored)
  new Buffer([0x15])  // No metadata or rules (no SHA1 or SHA2)
]
var BURN_OP_CODES = [
  new Buffer([0x20]), // All Hashes in OP_RETURN
  new Buffer([0x21]), // SHA2 in Pay-to-Script-Hash multi-sig output (1 out of 2)
  new Buffer([0x22]), // All Hashes in Pay-to-Script-Hash multi-sig outputs (1 out of 3)
  new Buffer([0x23]), // Low security transaction no SHA2 for torrent data. SHA1 is always inside OP_RETURN in this case.
  new Buffer([0x24]), // Low security transaction no SHA2 for torrent data. SHA1 is always inside OP_RETURN in this case. also no rules inside the metadata (if there are any they will be in ignored)
  new Buffer([0x25])  // No metadata or rules (no SHA1 or SHA2)
]

function TransferEncoder(params) {
  if (!(this instanceof TransferEncoder)) {
    return new TransferEncoder(params);
  }
  this.payments = params.payments;
  this.type = params.type;
  this.protocol = params.protocol;
  this.version = params.version;
  this.sha2 = params.sha2;
  this.torrentHash = params.torrentHash;
  this.noRules = params.noRules;
  this.output = params.output;
}

TransferEncoder.prototype.encode = function(byteSize) {
  $.checkState(this.payments, 'Missing Data');
  var opcode
  var OP_CODES = this.type === 'burn' ? BURN_OP_CODES : TRANSFER_OP_CODES;
  var paymentEncoder = this.type === 'burn' ? BurnPaymentEncoder : PaymentEncoder;
  var hash = new Buffer(0);
  var protocol = new Buffer(assetUtils.padLeadingZeros(this.protocol.toString(16), 2), 'hex');
  var version = new Buffer([this.version]);
  var transferHeader = Buffer.concat([protocol, version]);
  var payments = new paymentEncoder(this).encodeBulk(this.payments);
  var issueByteSize = transferHeader.length + payments.length + 1;

  if (issueByteSize > byteSize) throw new Error('Data code is bigger then the allowed byte size');
  if (!this.sha2) {
    if (this.torrentHash) {
      opcode = this.noRules ? OP_CODES[4] : OP_CODES[3];
      if (issueByteSize + this.torrentHash.length > byteSize) throw new Error('Can\'t fit Torrent Hash in byte size');
      return { codeBuffer: Buffer.concat([transferHeader, opcode, this.torrentHash, payments]), leftover: [] };
    }
    return { codeBuffer: Buffer.concat([transferHeader, OP_CODES[5], hash, payments]), leftover: [] };
  }
  if (!this.torrentHash) throw new Error('Torrent Hash is missing')
  var leftover = [this.torrentHash, this.sha2];

  opcode = OP_CODES[2];
  issueByteSize = issueByteSize + this.torrentHash.length;

  if (issueByteSize <= byteSize) {
    hash = Buffer.concat([hash, leftover.shift()]);
    opcode = OP_CODES[1];
    issueByteSize = issueByteSize + this.sha2.length;
  }
  if (issueByteSize <= byteSize) {
    hash = Buffer.concat([hash, leftover.shift()]);
    opcode = OP_CODES[0];
  }

  return { codeBuffer: Buffer.concat([transferHeader, opcode, hash, payments]), leftover: leftover };
}

TransferEncoder.prototype.decode = function(op_code_buffer) {
  var data = {};
  var consume = assetUtils.consumer(op_code_buffer);
  data.protocol = parseInt(consume(2).toString('hex'), 16);
  data.version = parseInt(consume(1).toString('hex'), 16);
  data.multiSig = [];
  var opcode = consume(1);
  var paymentEncoder;
  if ((opcode[0] & TYPE_MASK) === TRANSFER_MASK) {
    paymentEncoder = PaymentEncoder;
  } else if ((opcode[0] & TYPE_MASK) === BURN_MASK) {
    paymentEncoder = BurnPaymentEncoder;
  } else {
    throw new Error('Unrecognized Code');
  }

  if (opcode[0] === TRANSFER_OP_CODES[0][0] || opcode[0] === BURN_OP_CODES[0][0]) {
    data.torrentHash = consume(20);
    data.sha2 = consume(32);
  } else if (opcode[0] === TRANSFER_OP_CODES[1][0] || opcode[0] === BURN_OP_CODES[1][0]) {
    data.torrentHash = consume(20);
    data.multiSig.push({'index': 1, 'hashType': 'sha2'});
  } else if (opcode[0] === TRANSFER_OP_CODES[2][0] || opcode[0] === BURN_OP_CODES[2][0]) {
    data.multiSig.push({'index': 1, 'hashType': 'sha2'});
    data.multiSig.push({'index': 2, 'hashType': 'torrentHash'});
  } else if (opcode[0] === TRANSFER_OP_CODES[3][0] || opcode[0] === BURN_OP_CODES[3][0]) {
    data.torrentHash = consume(20);
    data.noRules = false;
  } else if (opcode[0] === TRANSFER_OP_CODES[4][0] || opcode[0] === BURN_OP_CODES[4][0]) {
    data.torrentHash = consume(20);
    data.noRules = true;
  } else if (opcode[0] === TRANSFER_OP_CODES[5][0] || opcode[0] === BURN_OP_CODES[5][0]) {
  } else {
    throw new Error('Unrecognized Code');
  }
  data.payments = new paymentEncoder().decodeBulk(consume);

  return new TransferEncoder(data);
}

module.exports = TransferEncoder;