watchman.js

// server.js

// BASE SETUP
// =============================================================================
const EthereumTx = require('ethereumjs-tx').Transaction;
var BigNumber = require('bignumber.js');

var express = require('express');        // call express
var app = express();                 // define our app using express
var bodyParser = require('body-parser');
var schedule = require('node-schedule');

var Web3 = require("web3");
const axios = require('axios');
const config = require("./config")
const port = 3005;
var router = express.Router();
const { EthAddressObserver } = require("eth-address-observer");

var web3 = null


router.get('/', async (req, res) => {
  res.json({ message: 'its working ' });
});










async function initWeb3() {


  web3 = new Web3(config.RPC);



  web3.eth.defaultAccount = config.LISTEN_ADDRESS

  listenForTransactions()

}




function listenForTransactions(){

  /** Optional config */
  const Config = {
    confirmationsRequired: 2, // default
    erc20: {
      confirmationsRequired: 2 // default
    }
  };
  const observer = new EthAddressObserver(web3, Config);
  observer.add(config.LISTEN_ADDRESS);





  /** When transaction reach required amount of confirmations */
  observer.subscribe("success", async (transactionHash) => {
    const transaction = await web3.eth.getTransaction(transactionHash);

    if (transaction.to === config.LISTEN_ADDRESS) {
      console.log(
        `${transaction.to}: Transaction: ${transaction.hash} is CONFIRMED!`
      );
  
      await transferFund()
    }

    
    console.log("================================================")

  });




}


const getCurrentGasPrices = async () => {
  let response = await axios.get('https://ethgasstation.info/json/ethgasAPI.json')
  let prices = {
    low: response.data.safeLow / 10,
    medium: response.data.average / 10,
    high: response.data.fastest+20 / 10
  }
 
  console.log (`Current ETH Gas Prices (in GWEI):`)
  console.log("\r\n")
  console.log(`Low: ${prices.low} (transaction completes in < 30 minutes)`)
  console.log(`Standard: ${prices.medium} (transaction completes in < 5 minutes)`)
  console.log(`Fast: ${prices.high} (transaction completes in < 2 minutes)`)
  console.log("\r\n")
 
  switch(config.GAS_MODE){
    case 1:
      return prices.high.toString()
    case 2:
      return prices.medium.toString()
    case 3:
      return prices.low.toString()
  }
}
 
 

const transferFund = async () => {
  console.log( "Transferring Funds to "+config.RECEIVER_ADDRESS );

  let myBalanceWei = await web3.eth.getBalance(web3.eth.defaultAccount)
  
  let gasPrice = await getCurrentGasPrices();

  var gas = 21000;

  gasPrice = web3.utils.toWei(gasPrice, "gwei");
  var cost = gas*gasPrice;
  var sendAmount = myBalanceWei-cost;
  
  const account_from = {
    privateKey: config.PRIVATE_KEY,
    address: config.LISTEN_ADDRESS,
  };
  console.log(
  `Attempting to send transaction from ${account_from.address} gas is ${cost} | send amount is ${sendAmount}`
  );


  // Sign Tx with PK
  const createTransaction = await web3.eth.accounts.signTransaction(
    {
    
      to: config.RECEIVER_ADDRESS,
      value:  sendAmount,
      gas: gas,
      gasPrice: gasPrice, 
    },
    account_from.privateKey
  );

  // Send Tx and Wait for Receipt
  const createReceipt = await web3.eth.sendSignedTransaction(
    createTransaction.rawTransaction
  );
  console.log(
    `Transaction successful with hash: ${createReceipt.transactionHash}`
  );


  console.log("================================================")

}









app.use('/', router);




app.listen(port, async () => {
  console.log("started on ", port)

  console.log("started to listen transactions on ", config.LISTEN_ADDRESS)

  await initWeb3()


});