1. minor update about borrow-erc20-with-eth-collateral 2. add borrowing based reinvestment pattern

.env.example

@@ -0,0 +1,4 @@
+INFURA_PROJECT_ID=
+ACCOUNT=
+PRIVATE_KEY=
+CHECK_EACH_X_MINUTES=1

.gitignore

@@ -1,3 +1,4 @@
 .DS_Store
 node_modules/
 .build/
+.env

borrowing-based-investment-examples/borrow-dai-with-eth-collateral-swap-to-eth-and-reinvest.ts

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+require("dotenv").config();
+
+import {
+  Fetcher,
+  Percent,
+  Route,
+  TokenAmount,
+  Trade,
+  TradeType,
+  WETH,
+} from "@uniswap/sdk";
+import { ethers } from "ethers";
+import { uniswapJSONInterface } from "./constants/uniswap-json-interface";
+const axios = require('axios')
+const Web3 = require('web3');
+const web3 = new Web3(new Web3.providers.HttpProvider(`https://mainnet.infura.io/v3/${process.env.INFURA_PROJECT_ID}`));
+
+const {
+  cEthAbi,
+  comptrollerAbi,
+  priceFeedAbi,
+  cErcAbi,
+  erc20Abi,
+} = require('../contracts.json');
+
+
+web3.eth.accounts.wallet.add('0x' + process.env.PRIVATE_KEY);
+const myWalletAddress = web3.eth.accounts.wallet[0].address;
+
+const cEthAddress = '0x4ddc2d193948926d02f9b1fe9e1daa0718270ed5';
+const cEthContract = new web3.eth.Contract(cEthAbi, cEthAddress);
+
+const comptrollerAddress = '0x3d9819210a31b4961b30ef54be2aed79b9c9cd3b';
+const comptroller = new web3.eth.Contract(comptrollerAbi, comptrollerAddress);
+
+const priceFeedAddress = '0x922018674c12a7f0d394ebeef9b58f186cde13c1';
+const priceFeed = new web3.eth.Contract(priceFeedAbi, priceFeedAddress);
+
+const underlyingAddress = '0x6B175474E89094C44Da98b954EedeAC495271d0F';
+
+const cTokenAddress = '0x5d3a536e4d6dbd6114cc1ead35777bab948e3643';
+const cToken = new web3.eth.Contract(cErcAbi, cTokenAddress);
+const assetName = 'DAI';
+const underlyingDecimals = 18;
+
+
+ensureEnvironmentIsReasonablyConfigured();
+
+const gasPriceLimitForInvestmentRound: number = 165000000000 // could be flexibilized
+let amountOfDAIToBeBorrowedInThisRound: number = 0 // initialization
+let freeValueInETH: number = 0 // initialization
+
+
+setInterval(async () => {
+  if (await isAnInvestmentRoundReasonable(gasPriceLimitForInvestmentRound)) {
+    console.log("starting an investmentround.");
+    await borrowDAIFromCompound(amountOfDAIToBeBorrowedInThisRound); 
+    await swapDAIToETH();
+    await depositETHToCompound(freeValueInETH * 0.7); // times 0.7 ensuring there stays ETH for gas in wallet
+  } else {
+    console.log("At the moment it does not make sense to trigger another investment round.");
+  }
+}, 1000 * 60 * Number(process.env.CHECK_EACH_X_MINUTES));
+
+
+function ensureEnvironmentIsReasonablyConfigured(): void {
+
+  if (process.env.ACCOUNT === undefined || process.env.ACCOUNT.length < 10) {
+    throw new Error(`Please copy the .env.example file to .env and add your data for the wallet you want to optimize.`);
+  } else {
+    console.log(`optimizing crypto investments for wallet: ${process.env.ACCOUNT} on a regular basis`);
+  }
+};
+
+
+// I would love to publish a deno.land module containing the following functions :)
+async function isAnInvestmentRoundReasonable(gasPriceLimitForInvestmentRound: number): Promise<boolean> {
+
+  const gasPrice = await web3.eth.getGasPrice()
+
+  const apiResult = (await axios.get(`https://api.compound.finance/api/v2/account?addresses[]=${process.env.ACCOUNT}`)).data
+  const totalCollateralValueInETH = apiResult.accounts[0].total_collateral_value_in_eth.value
+  const totalBorrowValueInETH = apiResult.accounts[0].total_borrow_value_in_eth.value
+  const healthFactor = apiResult.accounts[0].health.value
+
+  freeValueInETH = (totalCollateralValueInETH * 0.8) - totalBorrowValueInETH
+
+  if (gasPrice > gasPriceLimitForInvestmentRound) {
+    console.log(`The gas Price ${gasPrice} seems too high as your limit is set to ${gasPriceLimitForInvestmentRound}.`)
+
+    return false
+  }
+
+  if (healthFactor < 2) {
+    console.log(`The health factor of ${healthFactor} is below your limit of 2.`)
+
+    return false
+  }
+
+  console.log(`The gas price of ${gasPrice} is fine as your limit is set to ${gasPriceLimitForInvestmentRound}.`)
+  console.log(`The health factor of ${healthFactor} also allows for an additional investment round.`)
+
+  amountOfDAIToBeBorrowedInThisRound = await getAmountOfDAIWhichCanBeBorrowed()
+  console.log(`We could borrow ${amountOfDAIToBeBorrowedInThisRound}.`)
+
+  return true
+};
+
+async function getAmountOfDAIWhichCanBeBorrowed(): Promise<number> {
+
+  const priceFeedAddress = '0x922018674c12a7f0d394ebeef9b58f186cde13c1';
+  const priceFeed = new web3.eth.Contract(priceFeedAbi, priceFeedAddress);
+  let priceInUsd = (await priceFeed.methods.price('ETH').call()) / 1000000;
+
+  console.log(`According to the price feed address: The price for Ether is about ${priceInUsd} USD.`)
+
+  return freeValueInETH * priceInUsd * 0.9 // the "* 0.9" just ensures we handle the investment carefully
+}
+
+async function borrowDAIFromCompound(amountOfDAIToBeBorrowed: number) {
+
+  const fromMyWallet = {
+    from: myWalletAddress,
+    gasLimit: web3.utils.toHex(500000),
+    gasPrice: await web3.eth.getGasPrice()
+  };
+
+  let markets = [cEthAddress];
+  await comptroller.methods.enterMarkets(markets).send(fromMyWallet);
+
+  console.log('Calculating your liquid assets in the protocol...');
+  let { 1: liquidity } = await comptroller.methods.getAccountLiquidity(myWalletAddress).call();
+  liquidity = liquidity / 1e18;
+
+  console.log('Fetching cETH collateral factor...');
+  let { 1: collateralFactor } = await comptroller.methods.markets(cEthAddress).call();
+  collateralFactor = (collateralFactor / 1e18) * 100;
+
+  console.log(`Fetching ${assetName} price from the price feed...`);
+  let underlyingPriceInUsd = await priceFeed.methods.price(assetName).call();
+  underlyingPriceInUsd = underlyingPriceInUsd / 1e6; // Price feed provides price in USD with 6 decimal places
+
+  console.log(`Fetching borrow rate per block for ${assetName} borrowing...`);
+  let borrowRate = await cToken.methods.borrowRatePerBlock().call();
+  borrowRate = borrowRate / Math.pow(10, underlyingDecimals);
+
+  console.log(`Now attempting to borrow ${amountOfDAIToBeBorrowed} ${assetName}...`);
+  const scaledUpBorrowAmount = (amountOfDAIToBeBorrowed * Math.pow(10, underlyingDecimals)).toString();
+  const trx = await cToken.methods.borrow(scaledUpBorrowAmount).send(fromMyWallet);
+  console.log('Borrow Transaction', trx);
+
+  console.log(`\nFetching ${assetName} borrow balance from c${assetName} contract...`);
+  let balance = await cToken.methods.borrowBalanceCurrent(myWalletAddress).call();
+  balance = balance / Math.pow(10, underlyingDecimals);
+  console.log(`Borrow balance is ${balance} ${assetName}`);
+
+}
+
+
+async function swapDAIToETH(): Promise<void> {
+  const dai = (await Fetcher.fetchTokenData(1, underlyingAddress))
+  const pair = await Fetcher.fetchPairData(dai, WETH[1])
+  const route = new Route([pair], dai)
+  const signer = new ethers.Wallet(process.env.PRIVATE_KEY)
+  const provider = ethers.getDefaultProvider('mainnet', { infura: `https://mainnet.infura.io/v3/${process.env.INFURA_PROJECT_ID}` })
+  const account = signer.connect(provider)
+
+  const daiSmartContract = new ethers.Contract(underlyingAddress, erc20Abi, account)
+  const balanceOfDaiOnAccount = await daiSmartContract.balanceOf(process.env.ACCOUNT)
+  console.log(balanceOfDaiOnAccount)
+
+  const trade = new Trade(route, new TokenAmount(dai, balanceOfDaiOnAccount), TradeType.EXACT_INPUT)
+  console.log(route.midPrice.toSignificant(6))
+  console.log(trade.executionPrice.toSignificant(6))
+
+  const slippageTolerance = new Percent('50', '10000')
+  const amountOutMin = trade.minimumAmountOut(slippageTolerance).raw
+
+  console.log(amountOutMin.toString())
+
+  console.log(ethers.BigNumber.from("42"))
+
+  const path = [underlyingAddress, WETH[1].address]
+
+  const deadline = Math.floor(Date.now() / 1000) + 60 * 2
+
+  const uniswapSmartContract = new ethers.Contract('0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D', uniswapJSONInterface, account)
+
+  const tx = await uniswapSmartContract.swapExactTokensForETH(
+    balanceOfDaiOnAccount,
+    amountOutMin.toString(),
+    path,
+    process.env.ACCOUNT,
+    deadline
+  )
+
+  console.log(`Check your swap transaction at https://etherscan.io/tx/${tx.hash}`)
+}
+
+
+async function depositETHToCompound(amountToBeDeposited: number) {
+  await cEthContract.methods.mint().send({
+    from: myWalletAddress,
+    gasLimit: web3.utils.toHex(150000),
+    gasPrice: await web3.eth.getGasPrice(),
+    value: web3.utils.toHex(amountToBeDeposited * 1e18)
+  });
+
+  console.log(`deposited ${amountToBeDeposited} Ether to compound`)
+};

borrowing-based-investment-examples/constants/uniswap-json-interface.ts

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+export const uniswapJSONInterface = [{"inputs":[{"internalType":"address","name":"_factory","type":"address"},{"internalType":"address","name":"_WETH","type":"address"}],"stateMutability":"nonpayable","type":"constructor"},{"inputs":[],"name":"WETH","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"tokenA","type":"address"},{"internalType":"address","name":"tokenB","type":"address"},{"internalType":"uint256","name":"amountADesired","type":"uint256"},{"internalType":"uint256","name":"amountBDesired","type":"uint256"},{"internalType":"uint256","name":"amountAMin","type":"uint256"},{"internalType":"uint256","name":"amountBMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"addLiquidity","outputs":[{"internalType":"uint256","name":"amountA","type":"uint256"},{"internalType":"uint256","name":"amountB","type":"uint256"},{"internalType":"uint256","name":"liquidity","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"amountTokenDesired","type":"uint256"},{"internalType":"uint256","name":"amountTokenMin","type":"uint256"},{"internalType":"uint256","name":"amountETHMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"addLiquidityETH","outputs":[{"internalType":"uint256","name":"amountToken","type":"uint256"},{"internalType":"uint256","name":"amountETH","type":"uint256"},{"internalType":"uint256","name":"liquidity","type":"uint256"}],"stateMutability":"payable","type":"function"},{"inputs":[],"name":"factory","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"reserveIn","type":"uint256"},{"internalType":"uint256","name":"reserveOut","type":"uint256"}],"name":"getAmountIn","outputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"reserveIn","type":"uint256"},{"internalType":"uint256","name":"reserveOut","type":"uint256"}],"name":"getAmountOut","outputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"}],"name":"getAmountsIn","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"}],"name":"getAmountsOut","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountA","type":"uint256"},{"internalType":"uint256","name":"reserveA","type":"uint256"},{"internalType":"uint256","name":"reserveB","type":"uint256"}],"name":"quote","outputs":[{"internalType":"uint256","name":"amountB","type":"uint256"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"address","name":"tokenA","type":"address"},{"internalType":"address","name":"tokenB","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountAMin","type":"uint256"},{"internalType":"uint256","name":"amountBMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"removeLiquidity","outputs":[{"internalType":"uint256","name":"amountA","type":"uint256"},{"internalType":"uint256","name":"amountB","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountTokenMin","type":"uint256"},{"internalType":"uint256","name":"amountETHMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"removeLiquidityETH","outputs":[{"internalType":"uint256","name":"amountToken","type":"uint256"},{"internalType":"uint256","name":"amountETH","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountTokenMin","type":"uint256"},{"internalType":"uint256","name":"amountETHMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"removeLiquidityETHSupportingFeeOnTransferTokens","outputs":[{"internalType":"uint256","name":"amountETH","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountTokenMin","type":"uint256"},{"internalType":"uint256","name":"amountETHMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"bool","name":"approveMax","type":"bool"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"removeLiquidityETHWithPermit","outputs":[{"internalType":"uint256","name":"amountToken","type":"uint256"},{"internalType":"uint256","name":"amountETH","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountTokenMin","type":"uint256"},{"internalType":"uint256","name":"amountETHMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"bool","name":"approveMax","type":"bool"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"removeLiquidityETHWithPermitSupportingFeeOnTransferTokens","outputs":[{"internalType":"uint256","name":"amountETH","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"tokenA","type":"address"},{"internalType":"address","name":"tokenB","type":"address"},{"internalType":"uint256","name":"liquidity","type":"uint256"},{"internalType":"uint256","name":"amountAMin","type":"uint256"},{"internalType":"uint256","name":"amountBMin","type":"uint256"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"bool","name":"approveMax","type":"bool"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"removeLiquidityWithPermit","outputs":[{"internalType":"uint256","name":"amountA","type":"uint256"},{"internalType":"uint256","name":"amountB","type":"uint256"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapETHForExactTokens","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactETHForTokens","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactETHForTokensSupportingFeeOnTransferTokens","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactTokensForETH","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactTokensForETHSupportingFeeOnTransferTokens","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactTokensForTokens","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapExactTokensForTokensSupportingFeeOnTransferTokens","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"amountInMax","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapTokensForExactETH","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"amountInMax","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"deadline","type":"uint256"}],"name":"swapTokensForExactTokens","outputs":[{"internalType":"uint256[]","name":"amounts","type":"uint256[]"}],"stateMutability":"nonpayable","type":"function"},{"stateMutability":"payable","type":"receive"}]