cctp.js

const Web3 = require('web3')
require('dotenv').config();


const tokenMessengerAbi = require('./abis/cctp/TokenMessenger.json');
const usdcAbi = require('./abis/Usdc.json');
const messageTransmitterAbi = require('./abis/cctp/MessageTransmitter.json');


const waitForTransaction = async(web3, txHash) => {
    let transactionReceipt = await web3.eth.getTransactionReceipt(txHash);
    while(transactionReceipt != null && transactionReceipt.status === 'FALSE') {
        transactionReceipt = await web3.eth.getTransactionReceipt(txHash);
        await new Promise(r => setTimeout(r, 4000));
    }
    return transactionReceipt;
}

const main = async() => {


    const web3 = new Web3(process.env.ETH_TESTNET_RPC);
    
    // Add ETH private key used for signing transactions
    const ethSigner = web3.eth.accounts.privateKeyToAccount(process.env.ETH_PRIVATE_KEY);
    web3.eth.accounts.wallet.add(ethSigner);

    // // Add AVAX private key used for signing transactions
    const avaxSigner = web3.eth.accounts.privateKeyToAccount(process.env.AVAX_PRIVATE_KEY);
    web3.eth.accounts.wallet.add(avaxSigner);

    // Testnet Contract Addresses  // always update addresses based on documentation
    const ETH_TOKEN_MESSENGER_CONTRACT_ADDRESS = "0x9f3B8679c73C2Fef8b59B4f3444d4e156fb70AA5";
    const USDC_ETH_CONTRACT_ADDRESS = "0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238";
    const AVAX_MESSAGE_TRANSMITTER_CONTRACT_ADDRESS = '0xa9fB1b3009DCb79E2fe346c16a604B8Fa8aE0a79';

    // initialize contracts using address and ABI
    const ethTokenMessengerContract = new web3.eth.Contract(tokenMessengerAbi, ETH_TOKEN_MESSENGER_CONTRACT_ADDRESS);
    const usdcEthContract = new web3.eth.Contract(usdcAbi, USDC_ETH_CONTRACT_ADDRESS);
    const avaxMessageTransmitterContract = new web3.eth.Contract(messageTransmitterAbi, AVAX_MESSAGE_TRANSMITTER_CONTRACT_ADDRESS);

    // AVAX destination address
    const mintRecipient = process.env.RECIPIENT_ADDRESS;
    const AVAX_DESTINATION_DOMAIN = 1;

    // Amount that will be transferred
    const amount = process.env.AMOUNT;


    
    const approveTxGas = await usdcEthContract.methods.approve(ETH_TOKEN_MESSENGER_CONTRACT_ADDRESS, amount).estimateGas({from: ethSigner.address})
    const approveTx = await usdcEthContract.methods.approve(ETH_TOKEN_MESSENGER_CONTRACT_ADDRESS, amount).send({gas: approveTxGas, from: ethSigner.address})
    const approveTxReceipt = await waitForTransaction(web3, approveTx.transactionHash);
    console.log('ApproveTxReceipt: ', approveTxReceipt)
   

    // STEP 2: Burn USDC
    const burnTxGas = await ethTokenMessengerContract.methods.depositForBurn(amount, AVAX_DESTINATION_DOMAIN, mintRecipient, USDC_ETH_CONTRACT_ADDRESS).estimateGas({ from: ethSigner.address});
    const burnTx = await ethTokenMessengerContract.methods.depositForBurn(amount, AVAX_DESTINATION_DOMAIN, mintRecipient, USDC_ETH_CONTRACT_ADDRESS).send({gas: burnTxGas,  from: ethSigner.address});
    const burnTxReceipt = await waitForTransaction(web3, burnTx.transactionHash);
    console.log('BurnTxReceipt: ', burnTxReceipt)

    // STEP 3: Retrieve message bytes from logs
    const transactionReceipt = await web3.eth.getTransactionReceipt(burnTx.transactionHash);
    const eventTopic = web3.utils.keccak256('MessageSent(bytes)')
    const log = transactionReceipt.logs.find((l) => l.topics[0] === eventTopic)
    const messageBytes = web3.eth.abi.decodeParameters(['bytes'], log.data)[0]
    const messageHash = web3.utils.keccak256(messageBytes);

    console.log(`MessageBytes: ${messageBytes}`)
    console.log(`MessageHash: ${messageHash}`)

    // STEP 4: Fetch attestation signature
    let attestationResponse = {status: 'pending'};
    while(attestationResponse.status != 'complete') {
        const response = await fetch(`https://iris-api-sandbox.circle.com/attestations/${messageHash}`);
        attestationResponse = await response.json()
        await new Promise(r => setTimeout(r, 2000));
    }

    const attestationSignature = attestationResponse.attestation;
    console.log(`Signature: ${attestationSignature}`)

    // STEP 5: Using the message bytes and signature recieve the funds on destination chain and address
    web3.setProvider(process.env.AVAX_TESTNET_RPC); // Connect web3 to AVAX testnet
    const receiveTxGas = await avaxMessageTransmitterContract.methods.receiveMessage(messageBytes, attestationSignature).estimateGas({ from: ethSigner.address});
    const receiveTx = await avaxMessageTransmitterContract.methods.receiveMessage(messageBytes, attestationSignature).send({gas: receiveTxGas,  from: ethSigner.address});
    const receiveTxReceipt = await waitForTransaction(web3, receiveTx.transactionHash);
    console.log('ReceiveTxReceipt: ', receiveTxReceipt)
};

main()