closeCDP.ts

import { BitGo } from 'bitgo';
import * as ethUtil from 'ethereumjs-util';
import { getContractsFactory } from '../../../src/index';

const daiToken = getContractsFactory('eth').getContract('StandardERC20').instance('dai');

async function sendBitGoTx(): Promise<void> {
  /*
   * This assume you already have a CDP at Maker from our example createCDP
   * It also assume you already have a CDP setup
   * step 1 - Approve the number of tokens you would like the proxy to access
   */

  const bitGo = new BitGo({ env: 'prod' });
  const baseCoin = bitGo.coin('eth');
  const depositAmount = 5e18; // The amount of dai you want to deposit.
  const withdrawAmount = 1e17; // The amount of eth you want to withdraw.
  bitGo.authenticateWithAccessToken({ accessToken: 'access token' });
  const bitGoWallet = await baseCoin.wallets().get({ id: 'wallet id' });
  const walletPassphrase = 'password';

  // your proxy
  const proxyAddress = '0x17458bbdd96d6c19645457f5fae87ed5a07ad8fd';
  const daiSavingsRateProxy = getContractsFactory('eth').getContract('DSProxy').instance();
  daiSavingsRateProxy.address = proxyAddress;

  let { data, amount } = daiToken.methods().approve.call(
    {
      _spender: proxyAddress,
      _value: depositAmount.toString(10),
    });

  let transaction = await bitGoWallet.send({ data, amount, address: daiToken.address, walletPassphrase });
  console.dir(transaction);

  // Note this step only needs to be done once based on the amount you approve

  /*
   * ============================================ //
   * ============================================ //
   */

  // step 2 - Deposit Dai and withdraw ETH

  /*
   * Now we need to go get the cdp id of the cdp that you created. The easiest way to do this is go to
   * the Etherscan page for the Dai manager contract, here: https://etherscan.io/address/0x5ef30b9986345249bc32d8928b7ee64de9435e39#readContract
   * Enter your proxy address in the 'last' query, then press `Query`. It will return your cdpid
   */
  const cdp = '1913';

  // The following two addresses are constants in the MakerDAO MCD ecosystem. You can look them up and verify on Etherscan
  const daiJoin = '0x9759a6ac90977b93b58547b4a71c78317f391a28';
  const ethJoin = '0x2f0b23f53734252bda2277357e97e1517d6b042a';
  const manager = '0x5ef30b9986345249bc32d8928b7ee64de9435e39';

  const dsProxyActionsContract = getContractsFactory('eth').getContract('DSProxyActions').instance();

  const { data: internalData, address: proxyActionsAddress } = dsProxyActionsContract.methods()
        .wipeAndFreeETH.call({ manager, ethJoin, daiJoin, cdp, wadC: withdrawAmount.toString(10), wadD: depositAmount.toString(10) });

  // Build the external call for our proxy to deposit dai and withdaw eth
  ({ data, amount } = daiSavingsRateProxy.methods()
        .execute.call({
          _target: proxyActionsAddress,
          _data: ethUtil.toBuffer(internalData),
        }));
  // send the transaction through BitGo

  transaction = await bitGoWallet.send({
    data,
    address: daiSavingsRateProxy.address,
    amount,
    walletPassphrase,
  });

  console.dir(transaction);
}

sendBitGoTx();