index.js

require('dotenv').config()
const express = require('express')
const bodyParser = require('body-parser')
const http = require('http')
const moment = require('moment-timezone')
const numeral = require('numeral')
const _ = require('lodash')
const axios = require('axios')

// ethereum dependencies
const ethers = require('ethers');
const { parseUnits, formatUnits } = ethers.utils;
const { legos } = require('@studydefi/money-legos');

// SERVER CONFIG
const PORT = process.env.PORT || 5001
const app = express();
const server = http.createServer(app).listen(PORT, () => console.log(`Listening on ${ PORT }`))

// ETHERS CONFIG
const provider = new ethers.providers.JsonRpcProvider(process.env.RPC_URL);

// Contract UniswapV2Router02 https://etherscan.io/address/0x7a250d5630b4cf539739df2c5dacb4c659f2488d#code
const uniswapV2 = new ethers.Contract(
  '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D',
  [
    'function getAmountsOut(uint256 amountIn, address[] calldata path) external view returns (uint256[] memory amounts)',
    'function WETH() external pure returns (address)'
  ],
  provider
);

// Contract Kyber Network V2  
const kyber = new ethers.Contract(legos.kyber.network.address, legos.kyber.network.abi, provider);


async function checkPair(args) {
  const { inputTokenSymbol, inputTokenAddress, outputTokenSymbol, outputTokenAddress, inputAmount } = args

  // calculate uniswap amount
  const path = [inputTokenAddress, outputTokenAddress];
  const amounts = await uniswapV2.getAmountsOut(inputAmount, path);
  const uniswapAmount = amounts[1];

  // calculate kyber amount
  const { expectedRate, slippageRate } = await kyber.getExpectedRate(inputTokenAddress, outputTokenAddress, inputAmount);
  const kyberExpectedAmount = expectedRate;
  const kyberSlippageAmount = slippageRate;

  console.table([{
    'Input Token': inputTokenSymbol,
    'Output Token': outputTokenSymbol,
    'Input Amount': formatUnits(inputAmount, 18),
    'Uniswap Return': formatUnits(uniswapAmount, 18),
    'Kyber Expected Rate': formatUnits(kyberExpectedAmount, 18),
    'Kyber Min Return': formatUnits(kyberSlippageAmount, 18),
    'Timestamp': moment().tz('America/Chicago').format(),
  }])
}

let priceMonitor
let monitoringPrice = false

async function monitorPrice() {
  if(monitoringPrice) {
    return
  }

  console.log("Checking prices...")
  monitoringPrice = true

  try {

    // ADD YOUR CUSTOM TOKEN PAIRS HERE!!!
    const WETH_ADDRESS = await uniswapV2.WETH(); // Uniswap V2 uses wrapped eth

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'DAI',
      outputTokenAddress: '0x6b175474e89094c44da98b954eedeac495271d0f',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'KNC',
      outputTokenAddress: '0xdd974d5c2e2928dea5f71b9825b8b646686bd200',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'LINK',
      outputTokenAddress: '0x514910771af9ca656af840dff83e8264ecf986ca',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'MKR',
      outputTokenAddress: '0x9f8f72aa9304c8b593d555f12ef6589cc3a579a2',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'MATIC',
      outputTokenAddress: '0x7D1AfA7B718fb893dB30A3aBc0Cfc608AaCfeBB0',
      inputAmount: parseUnits('1', 18)
    })
    
    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'UNI',
      outputTokenAddress: '0x1f9840a85d5aF5bf1D1762F925BDADdC4201F984',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'BAT',
      outputTokenAddress: legos.erc20.bat.address,
      inputAmount: parseUnits('1', 18)
    })
        
    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'SNX',
      outputTokenAddress: '0xC011a73ee8576Fb46F5E1c5751cA3B9Fe0af2a6F',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'BNT',
      outputTokenAddress: '0x1F573D6Fb3F13d689FF844B4cE37794d79a7FF1C',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: '1INCH',
      outputTokenAddress: '0x111111111117dC0aa78b770fA6A738034120C302',
      inputAmount: parseUnits('1', 18)
    })

    // Kyber Rates?
    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'GETH',
      outputTokenAddress: '0xdD69DB25F6D620A7baD3023c5d32761D353D3De9',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'GRT',
      outputTokenAddress: '0xc944E90C64B2c07662A292be6244BDf05Cda44a7',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'ENS',
      outputTokenAddress: '0xC18360217D8F7Ab5e7c516566761Ea12Ce7F9D72',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'EWTB',
      outputTokenAddress: '0x178c820f862B14f316509ec36b13123DA19A6054',
      inputAmount: parseUnits('1', 18)
    })

    // Uniswap Rates?
    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'OCEAN',
      outputTokenAddress: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48',
      inputAmount: parseUnits('1', 18)
    })

    await checkPair({
      inputTokenSymbol: 'WETH',
      inputTokenAddress: WETH_ADDRESS,
      outputTokenSymbol: 'UBT',
      outputTokenAddress: '0x8400D94A5cb0fa0D041a3788e395285d61c9ee5e',
      inputAmount: parseUnits('1', 18)
    })



  } catch (error) {
    console.error(error)
    monitoringPrice = false
    clearInterval(priceMonitor)
    return
  }

  monitoringPrice = false
}

// Check markets every 3 seconds
const POLLING_INTERVAL = process.env.POLLING_INTERVAL || 3000 // 3 Seconds
priceMonitor = setInterval(async () => { await monitorPrice() }, POLLING_INTERVAL)