Example code redeeming free USDRIF

In the following example we will show how to invoke redeemFreeStableTokenVendors from RIF On Chain contract. This method allows to redeem USDRIF outside the settlement and they are limited by user balance. Check the USDRIF redeemption section for more details.

We will learn how to:

• Get the maximum amount of USDRIF available to redeem.

• Get USDRIF balance of an account.

• Redeem USDRIF.

You can find code examples into /examples dir. We will use truffle and testnet network. First we create a new node project.

mkdir example-redeem-free-stabletoken
cd example-redeem-free-stabletoken
npm init

Let's add the necessary dependencies to run the project.

npm install --save web3

Example

const Web3 = require('web3');
//You must compile the smart contracts or use the official ABIs of the repository
const MoC = require('../../build/contracts/MoC.json');
const MocState = require('../../build/contracts/MoCState.json');
const StableToken = require('../../build/contracts/StableToken.json');
const truffleConfig = require('../../truffle');
/**
 * Get a provider from truffle.js file
 * @param {String} network
 */
const getDefaultProvider = network =>
  truffleConfig.networks[network].provider || truffleConfig.networks[network].endpoint;

/**
 * Get a gasPrice from truffle.js file
 * @param {String} network
 */
const getGasPrice = network => truffleConfig.networks[network].gasPrice || 60000000;

/**
 * Get a new web3 instance from truffle.js file
 */
const getWeb3 = network => {
  const provider = getDefaultProvider(network);
  return new Web3(provider, null, {
    transactionConfirmationBlocks: 1
  });
};

const web3 = getWeb3('mocTestnet');
const gasPrice = getGasPrice('mocTestnet');

//Contract addresses on testnet
const mocAddress = '<contract-address>';
const mocStateAddress = '<contract-address>';
const stableTokenAddress = '<contract-address>';

const execute = async () => {
  web3.eth.defaultGas = 2000000;

  /**
   * Loads an specified contract
   * @param {ContractABI} abi
   * @param {String} contractAddress
   */
  const getContract = async (abi, contractAddress) => new web3.eth.Contract(abi, contractAddress);

  // Loading MoC contract
  const moc = await getContract(MoC.abi, mocAddress);
  if (!moc) {
    throw Error('Can not find MoC contract.');
  }

  // Loading mocState contract. It is necessary to compute free RDoc
  const mocState = await getContract(MocState.abi, mocStateAddress);
  if (!mocState) {
    throw Error('Can not find MoCState contract.');
  }

  // Loading StableToken contract. It is necessary to compute user balance
  const stableToken = await getContract(StableToken.abi, stableTokenAddress);
  if (!stableToken) {
    throw Error('Can not find StableToken contract.');
  }

  const [from] = await web3.eth.getAccounts();

  const redeemFreeStableToken = async (stableTokenAmount, vendorAccount) => {
    const weiAmount = web3.utils.toWei(stableTokenAmount, 'ether');

    console.log(`Calling redeem USDRIF request, account: ${from}, amount: ${weiAmount}.`);
    moc.methods
      .redeemFreeStableTokenVendors(weiAmount, vendorAccount)
      .send({ from, gasPrice }, function(error, transactionHash) {
        if (error) console.log(error);
        if (transactionHash) console.log('txHash: '.concat(transactionHash));
      })
      .on('transactionHash', function(hash) {
        console.log('TxHash: '.concat(hash));
      })
      .on('receipt', function(receipt) {
        console.log(receipt);
      })
      .on('error', console.error);
  };

  const stableTokenAmount = '10000';
  const freeStableToken = await mocState.methods.freeStableToken().call();
  const userStableTokenBalance = await stableTokenToken.methods.balanceOf(from).call();
  const finalStableTokenAmount = Math.min(freeStableToken, userStableTokenBalance);
  const vendorAccount = '<vendor-address>';

  console.log('User USDRIF balance: ', userStableTokenBalance.toString());
  console.log('=== Max Available USDRIF to redeem: ', finalStableTokenAmount);

  // Call redeem
  await redeemFreeStableToken(stableTokenAmount, vendorAccount);
};

execute()
  .then(() => console.log('Completed'))
  .catch(err => {
    console.log('Error', err);
  });