DEV Community: Filosofía Código FR

Tokens avec des Fees en Uniswap V3. C'est possible?

Ahmed Castro — Tue, 07 Feb 2023 19:41:56 +0000

Uniswap a été lancé en 2021 et aujourd'hui c'est le DEX avec le plus de volume. Dans cette vidéo, nous examinerons comment il fonctionne en concentrant la liquidité à travers les NFT et nous lancerons un token qui extrait des commissions percentuelles sur l'achat et le P2P.

Avant de commencer

For this tutorial you will need Metamask or another compatible wallet with Goerli funds that you can get from a faucet.

Pour ce tutoriel tu vas avoir besoin de Metamask ou n'importe quel wallet compatible avec l'EVM et aussi du GoerliETH que tu peux trouver gratuitement dans un faucet.

Contrat intelligent avec des fees dans Uniswap V3

Vouz pouvez lancer ce token en Mainnet et en Goerli car Uniswap a les memes addresses. Mais vous devrez changes les addresses de ‘Base Token’avec l'addresse de WETH en Mainnet 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 et en Goerli 0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6.

Vous pouvez trouver plus en Biblioteca y plus de detail des parametres dans la Documentation.

// SPDX-License-Identifier: MIT
pragma solidity 0.8.18;

import "biblioteca/contracts/ERC20/UniswapV3FeeToken.sol";

contract MyUniswapV3FeeToken is UniswapV3FeeToken
{
    constructor() UniswapV3FeeToken(
        "My Token", "MTKN",                         // Name and Symbol
        1_000_000_000 ether,                        // 1 billion supply
        100, 200,                                   // Fees: 1% buy 2% P2P
        msg.sender,                                 // Vault Address
        0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6, // Base token: WETH
        1_000_000)                                  // Initial rate: 1 WETH = 1,000,000 tokens
    {
    }
}

¡Merci pour voir cette video!

Suivez nous ici en dev.to et en Youtube pour tout ce qui a à voir avec Blockchain en Francais.

Transactions sans paiement de gaz sur Ethereum

Ahmed Castro — Fri, 06 Jan 2023 18:14:57 +0000

L'Account Abstraction, les Rollups et la confidentialité sur le Blockchain sont possibles grâce à la capacité d'exécuter des transactions au nom de quelqu'un d'autre de manière sécurisée. Dans cette vidéo, nous allons créer une transaction sans payer de gaz qui sera exécutée par un Relayer en utilisant un contrat intelligent de vérification. Tout cela se fait de manière sécurisée grâce à la cryptographie. J'espère que cette vidéo vous aidera à comprendre vers où se dirige la chaîne de blocs.

Avant de commencer

Pour ce tutoriel tu vas avoir besoin de NodeJs, je vous conseille de le télécharger avec NVM, de plus tu auras besoin de Metamask ou n'importe quel wallet compatible avec l'EVM et aussi du GoerliETH que tu peux trouver gratuitement dans un faucet. Vous aurrez aussi besoin d'une Infura API Key.

Le contrat intelligent de vérification

Nous lancerons d'abord le contrat de vérification sur Goerli Testnet

// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

import "@openzeppelin/contracts/utils/cryptography/SignatureChecker.sol";
using ECDSA for bytes32;

contract VerifierHelloWorld  {
    string public hello = "Hello world!";
    address public helloSetter;

    function _verify(bytes32 helloHash, address _helloSetter, bytes memory signature) internal pure returns (bool)
    {
        return helloHash
            .toEthSignedMessageHash()
            .recover(signature) == _helloSetter;
    }

    function relaySetHello(string memory _hello, address _helloSetter, bytes memory signature) public
    {
        require(_verify(bytes32(abi.encodePacked(_hello)), _helloSetter, signature), "Invalid signature");
        hello = _hello;
        helloSetter = _helloSetter;
    }
}

Le Frontend

Ensuite, nous construisons le frontend qui consiste en un fichier HTML et JS. Le frontend est l'interface qui nous permet de signer des transactions et de les envoyer au Relayer.

index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
</head>
<body>
  <div>
    <h3>Hello Verifier</h3>
    <input id="connect_button" type="button" value="Connect" onclick="connectWallet()" style="display: none"></input>
    <p id="account_address" style="display: none"></p>
    <p id="web3_message"></p>
    <p id="contract_state"></p>
    <input type="text" id="_hello"></input>
    <button type="button" id="sign" onclick="_signMessage()" value="Hello!">Sign</button>
    <p id="hashed_message"></p>
    <p id="signature"></p>
    <h4>Hello Verifier</h4>
    <span>Hello</span><br>
    <input type="text" id="_helloRelay"></input><br>
    <span>Hello Setter</span><br>
    <input type="text" id="_helloSetterRelay"></input><br>
    <span>Signature</span><br>
    <input type="text" id="_signatureRelay"></input><br>
    <button type="button" id="relay" onclick="_relaySetHello()">Relay</button>
  </div>
  <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/web3/1.3.5/web3.min.js"></script>
  <script type="text/javascript" src="blockchain_stuff.js"></script>
</body>

  <script>
    function _signMessage()
    {
      _hello = document.getElementById("_hello").value
      signMessage(_hello)
    }

    function _relaySetHello()
    {
      _helloRelay = document.getElementById("_helloRelay").value
      _helloSetterRelay = document.getElementById("_helloSetterRelay").value
      _signatureRelay = document.getElementById("_signatureRelay").value
      relaySetHello(_helloRelay, _helloSetterRelay, _signatureRelay)
    }
  </script>
</html>

En JavaScript, n'oubliez pas de définir la variable MY_CONTRACT_ADDRESS avec le contrat que vous venez de lancer.

blockchain_stuff.js

const NETWORK_ID = 5

const MY_CONTRACT_ADDRESS = "0xE59da879e33b71C145b7c526a7B8C5b93195C51D"
const MY_CONTRACT_ABI_PATH = "./json_abi/Contract.json"
var my_contract

var accounts
var web3

function metamaskReloadCallback() {
  window.ethereum.on('accountsChanged', (accounts) => {
    document.getElementById("web3_message").textContent="Se cambió el account, refrescando...";
    window.location.reload()
  })
  window.ethereum.on('networkChanged', (accounts) => {
    document.getElementById("web3_message").textContent="Se el network, refrescando...";
    window.location.reload()
  })
}

const getWeb3 = async () => {
  return new Promise((resolve, reject) => {
    if(document.readyState=="complete")
    {
      if (window.ethereum) {
        const web3 = new Web3(window.ethereum)
        window.location.reload()
        resolve(web3)
      } else {
        reject("must install MetaMask")
        document.getElementById("web3_message").textContent="Error: Porfavor conéctate a Metamask";
      }
    }else
    {
      window.addEventListener("load", async () => {
        if (window.ethereum) {
          const web3 = new Web3(window.ethereum)
          resolve(web3)
        } else {
          reject("must install MetaMask")
          document.getElementById("web3_message").textContent="Error: Please install Metamask";
        }
      });
    }
  });
};

const getContract = async (web3, address, abi_path) => {
  const response = await fetch(abi_path);
  const data = await response.json();

  const netId = await web3.eth.net.getId();
  contract = new web3.eth.Contract(
    data,
    address
    );
  return contract
}

async function loadDapp() {
  metamaskReloadCallback()
  document.getElementById("web3_message").textContent="Please connect to Metamask"
  var awaitWeb3 = async function () {
    web3 = await getWeb3()
    web3.eth.net.getId((err, netId) => {
      if (netId == NETWORK_ID) {
        var awaitContract = async function () {
          my_contract = await getContract(web3, MY_CONTRACT_ADDRESS, MY_CONTRACT_ABI_PATH)
          document.getElementById("web3_message").textContent="You are connected to Metamask"
          onContractInitCallback()
          web3.eth.getAccounts(function(err, _accounts){
            accounts = _accounts
            if (err != null)
            {
              console.error("An error occurred: "+err)
            } else if (accounts.length > 0)
            {
              onWalletConnectedCallback()
              document.getElementById("account_address").style.display = "block"
            } else
            {
              document.getElementById("connect_button").style.display = "block"
            }
          });
        };
        awaitContract();
      } else {
        document.getElementById("web3_message").textContent="Please connect to Goerli";
      }
    });
  };
  awaitWeb3();
}

async function connectWallet() {
  await window.ethereum.request({ method: "eth_requestAccounts" })
  accounts = await web3.eth.getAccounts()
  onWalletConnectedCallback()
}

loadDapp()

const onContractInitCallback = async () => {
  var hello = await my_contract.methods.hello().call()
  var helloSetter = await my_contract.methods.helloSetter().call()

  var contract_state = "Hello: " + hello
    + ", helloSetter: " + helloSetter

  document.getElementById("contract_state").textContent = contract_state;
}

const onWalletConnectedCallback = async () => {
}

// Sign and Relay functions

async function signMessage(message)
{
  const hashedMessage = Web3.utils.asciiToHex(message).padEnd(66,'0');

  const signature = await ethereum.request({
    method: "personal_sign",
    params: [hashedMessage, accounts[0]],
  });

  //document.getElementById("hashed_message").textContent="Hashed Message: " + hashedMessage.padEnd(66,'0');
  document.getElementById("signature").textContent="Signature: " + signature;

  // split signature
  /*
  const r = signature.slice(0, 66);
  const s = "0x" + signature.slice(66, 130);
  const v = parseInt(signature.slice(130, 132), 16);
  console.log({ r, s, v });
  */
}

async function relaySetHello(helloRelay, helloSetterRelay, signatureRelay)
{
  var url = "http://localhost:8080/relay?"
  url += "hello=" + helloRelay
  url += "&helloSetter=" + helloSetterRelay
  url += "&signature=" + signatureRelay

  const myRequest = new Request(url, {
    method: 'GET',
    headers: new Headers(),
    mode: 'cors',
    cache: 'default',
  });

  fetch(myRequest);

  alert("Message sent!")
}

Le Backend Relayer

Voici un exemple de backend qui s'occupe de transmettre des transactions au Blockchain.

N'oubliez pas de définir la variable CONTRACT_ADDRESS avec le contrat que vous venez de lancer. Et BACKEND_WALLET_ADDRESS avec la wallet qui paiera les fonds.

backend.js

import createAlchemyWeb3 from "@alch/alchemy-web3"
import dotenv from "dotenv"
import fs from "fs"
import cors from "cors"
import express from "express"

const app = express()
dotenv.config();

const CONTRACT_ADDRESS = "0xE59da879e33b71C145b7c526a7B8C5b93195C51D"
const BACKEND_WALLET_ADDRESS = "0x18747BE67c5886881075136eb678cEADaf808028"
const JSON_CONTRACT_PATH = "./json_abi/Contract.json"
const PORT = 8080
var web3 = null
var contract = null

const loadContract = async (data) => {
  data = JSON.parse(data);

  const netId = await web3.eth.net.getId();
  contract = new web3.eth.Contract(
    data,
    CONTRACT_ADDRESS
  );
}

async function initAPI() {
  const { GOERLI_RPC_URL, PRIVATE_KEY } = process.env;
  web3 = createAlchemyWeb3.createAlchemyWeb3(GOERLI_RPC_URL);

  fs.readFile(JSON_CONTRACT_PATH, 'utf8', function (err,data) {
    if (err) {
      return console.log(err);
    }
    loadContract(data, web3)
  });

  app.listen(PORT, () => {
    console.log(`Listening to port ${PORT}`)
  })
  app.use(cors({
    origin: '*'
  }));
}

async function relaySetHello(hello, helloSetter, signature)
{
  const nonce = await web3.eth.getTransactionCount(BACKEND_WALLET_ADDRESS, 'latest'); // nonce starts counting from 0
  const transaction = {
   'from': BACKEND_WALLET_ADDRESS,
   'to': CONTRACT_ADDRESS,
   'value': 0,
   'gas': 300000,
   'nonce': nonce,
   'data': contract.methods.relaySetHello(
     hello,
     helloSetter,
     signature)
     .encodeABI()
  };
  const { GOERLI_RPC_URL, PRIVATE_KEY } = process.env;
  const signedTx = await web3.eth.accounts.signTransaction(transaction, PRIVATE_KEY);

  web3.eth.sendSignedTransaction(signedTx.rawTransaction, function(error, hash) {
    if (!error) {
      console.log("🎉 The hash of your transaction is: ", hash, "\n");
    } else {
      console.log("❗Something went wrong while submitting your transaction:", error)
    }
  });
}

//http://localhost:8080/relay?helloSetter=0x18747BE67c5886881075136eb678cEADaf808028&hello=hola&signature=0x6903cb647fb3d47b91e8aecc8adc686466557d5edf96814e2b21c745f455a8502e895e696c59f8d65fd9bb57e4f202d45bb6a40c07bc8fd283d666f31264ce411b
app.get('/relay', (req, res) => {
  var hello = req.query["hello"]
  var helloSetter = req.query["helloSetter"]
  var signature = req.query["signature"]
  var message = helloSetter + " setted hello to " + " " + hello
  relaySetHello(hello, helloSetter, signature)
  res.setHeader('Content-Type', 'application/json');
  res.send({
    "message": message
  })
})
initAPI()

Nous devrons également ajouter le fichier json_abi/Contract.json qui contient le Json ABI du contrat que nous venons de lancer.

json_abi/Contract.json

[
    {
        "inputs": [],
        "name": "hello",
        "outputs": [
            {
                "internalType": "string",
                "name": "",
                "type": "string"
            }
        ],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [],
        "name": "helloSetter",
        "outputs": [
            {
                "internalType": "address",
                "name": "",
                "type": "address"
            }
        ],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [
            {
                "internalType": "string",
                "name": "_hello",
                "type": "string"
            },
            {
                "internalType": "address",
                "name": "_helloSetter",
                "type": "address"
            },
            {
                "internalType": "bytes",
                "name": "signature",
                "type": "bytes"
            }
        ],
        "name": "relaySetHello",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    }
]

Et n'oubliez pas également d'ajouter un .env avec votre url RPC et votre clé privée.

.env

GOERLI_RPC_URL=YOURURLHERE
PRIVATE_KEY=YOURKEYHERE

package.json

{
  "name": "relayer-demo",
  "version": "1.0.0",
  "description": "",
  "main": "backend.js",
  "type": "module",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node backend.js"
  },
  "keywords": [],
  "author": "Filosofía Código",
  "license": "MIT",
  "dependencies": {
    "@alch/alchemy-web3": "^1.4.7",
    "dotenv": "^16.0.3",
    "node-fetch": "^3.3.0"
  }
}

Enfin, nous installons les dépendances:

npm install

Ou, alternativement, nous installons manuellement les dépendances: npm install @alch/alchemy-web3 dotenv node-fetch.

Tester la DApp

Pour démarrer le frontend

npm install -g lite-server
lite-server

Pour démarrer le backend Relayer

node backend.js

Vous pouvez maintenant signer et relayer des transactions

¡Merci pour voir cette video!

Suivez nous ici en dev.to et en Youtube pour tout ce qui a à voir avec Blockchain en Francais.

Explorer les contrats intelligents de Sudoswap

Ahmed Castro — Thu, 22 Dec 2022 17:47:53 +0000

Sudoswap est un protocole très innovant qui combine des idées déjà connues. Il permet d'acheter et de vendre des NFTs de la même manière que les autres marketplaces, mais il le fait en utilisant des pools de liquidité comme sur Uniswap. Je pense que c'est une idée intéressante à explorer. Dans cette vidéo, je vais vous expliquer comment fonctionne Sudoswap et partager un peu mon expérience et mon travail avec ce protocole.

Avant de commencer

¿Autofloor?

Sudoswap offre beaucoup de créativité. Ci-dessous, je montre en exemple un token conçu pour que le lancement du token (marché primaire) se fasse dans une piscine de liquidité à l'intérieur de Sudoswap. De cette façon, il ne sera pas nécessaire d'utiliser une page de mintage externe. De plus, ce token contient la fonctionnalité Autofloor, où un pourcentage des fonds générés dans la piscine de lancement est transféré automatiquement à un autre contrat qui sert à offrir aux holders qui souhaitent quitter le marché une option de vente immédiate et garantie.

// SPDX-License-Identifier: AGPL-3.0
pragma solidity 0.8.16;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Counters.sol";

contract ICurve{}

abstract contract LSSVMPair
{
    enum PoolType {
        TOKEN,
        NFT,
        TRADE
    }
}

contract LSSVMPairETH {
    function changeSpotPrice(uint128 newSpotPrice) external {
    }
}

contract LSSVMPairFactory {
    function createPairETH(
        IERC721 _nft,
        ICurve _bondingCurve,
        address payable _assetRecipient,
        LSSVMPair.PoolType _poolType,
        uint128 _delta,
        uint96 _fee,
        uint128 _spotPrice,
        uint256[] calldata _initialNFTIDs
    ) external payable returns (LSSVMPairETH pair) {
    }
}

contract MyNFT is ERC721Enumerable, Ownable {
    using Counters for Counters.Counter;
    Counters.Counter public tokenCounter;
    uint256 public token_count;

    LSSVMPairFactory public factory;
    LSSVMPairETH public nftPair;
    LSSVMPairETH public tokenPair;

    uint public MAX_AMOUNT = 10000;

    uint128 public mintPrice;
    uint128 public autoFloorPrice;
    uint public autoFloorFeePercentage;
    address public autoFloorNFTReciever;
    uint public  FEE_DECIMAL = 2;

    address public a1;
    address public a2;
    address public a3;

    string public baseTokenURI = "https://api.io/";

    // Constructor and init

    constructor() ERC721("My NFT", "MNFT") {
        mintPrice = 0.04 ether;
        autoFloorPrice = 0.02 ether;
        autoFloorFeePercentage = 5000; // 50%
        autoFloorNFTReciever = 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045;
        a1 = 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045;
        a2 = 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045;
        a3 = 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045;
    }

    function initializeSale(address factoryAddress) public {
        factory = LSSVMPairFactory(factoryAddress);
        uint[] memory initialNFTIDs = new uint[](10);
        address payable recipient = payable(this);

        while(tokenCounter.current()<10)
        {
            initialNFTIDs[tokenCounter.current()] = tokenCounter.current();
            _mint(address(this),tokenCounter.current());
            _approve(factoryAddress, tokenCounter.current());
            tokenCounter.increment();
        }

        nftPair = factory.createPairETH(
            IERC721(address(this)),
            ICurve(0x5B6aC51d9B1CeDE0068a1B26533CAce807f883Ee), // Lineal
            recipient,  // This contract
            LSSVMPair.PoolType.NFT,// NFT, TOKEN, TRADE
            0e18,       // Delta
            0,          // Fee
            mintPrice,  // Initial price
            initialNFTIDs
        );

        uint[] memory emptyArray = new uint[](0);
        tokenPair = factory.createPairETH(
            IERC721(address(this)),
            ICurve(0x5B6aC51d9B1CeDE0068a1B26533CAce807f883Ee), // Lineal
            payable(autoFloorNFTReciever), // This contract
            LSSVMPair.PoolType.TOKEN,// NFT, TOKEN, TRADE
            0e18,       // Delta
            0,          // Fee
            autoFloorPrice, // Initial price
            emptyArray
        );
    }

    // View functions

    function getNFTPairAddress() public view returns(address) {
        return address(nftPair);
    }

    function getTokenPairAddress() public view returns(address) {
        return address(tokenPair);
    }

    // Override functions

    function _baseURI() internal view virtual override returns (string memory) {
        return baseTokenURI;
    }

    function _afterTokenTransfer(address from, address to, uint256 tokenId) internal override(ERC721)
    {
        require(to != address(nftPair), "Can't send to mint pair");
        if(from != address(0))
        {
            if(from == address(nftPair) && uint(tokenCounter.current()) < MAX_AMOUNT)
            {
                _mint(address(nftPair), tokenCounter.current());
                tokenCounter.increment();
            }
        }
        super._afterTokenTransfer(from, to, tokenId);
    }

    function _safeTransfer(
        address from,
        address to,
        uint256 tokenId,
        bytes memory data
    ) internal override {
        data;
        _transfer(from, to, tokenId);
    }

    // Owner functions

    function setAutoFloorFeePercentage(uint value) public onlyOwner
    {
        autoFloorFeePercentage = value;
    }

    function setMintPrice(uint128 value) public onlyOwner
    {
        mintPrice = value;
        nftPair.changeSpotPrice(value);
    }

    function setAutoFloorPrice(uint128 value) public onlyOwner
    {
        autoFloorPrice = value;
        tokenPair.changeSpotPrice(value);
    }

    function setAddresses(address[] memory _a) public onlyOwner {
        a1 = _a[0];
        a2 = _a[1];
        a3 = _a[2];
    }

    function withdrawTeam(uint256 amount) public payable onlyOwner {
        uint256 percent = amount / 100;
        bool sent;
        bytes memory data;
        (sent, data) = payable(a1).call{value: percent * 40}("");
        require(sent, "Failed to send Ether");
        (sent, data) = payable(a2).call{value: percent * 30}("");
        require(sent, "Failed to send Ether");
        (sent, data) = payable(a3).call{value: percent * 30}("");
        require(sent, "Failed to send Ether");
    }

    function setBaseURI(string memory baseURI) public onlyOwner {
        baseTokenURI = baseURI;
    }

    // Fallback functions

    fallback() external payable {
    }

    receive() external payable {
        uint256 transferAmount = (msg.value) * (autoFloorFeePercentage) / (10**(FEE_DECIMAL + 2));
        (bool sent, bytes memory data) = address(tokenPair).call{value: transferAmount}("");
        data;
        require(sent, "Failed to send Ether");
    }
}

Faire des tests

En plus, j'ai préparé un petit paquet de tests unitaires pour ceux qui souhaitent approfondir ce sujet.

git clone https://github.com/FilosofiaCodigo/SudoswapToken
cd SudoswapToken
npm install

Aussi, creez un fichier .env avec lo meme format que .env.example. Et ajoutez votre URL RPC.

.env

RPC_URL=RPCURLHERE

Finally run the tests.

npx test

¡Merci pour voir cette video!

Suivez nous ici en dev.to et en Youtube pour tout ce qui a à voir avec Blockchain en Francais.

Comment lancer un DEX pas à pas

Ahmed Castro — Tue, 29 Nov 2022 21:01:50 +0000

Il y a quelque temps j'ai lancé un DEX en Mainnet pour un client. Dans cette vidéo je montre comment on l'a fait. De plus, j'explique les smart contrats nécessaires: le Factory, le Router et les Pairs. On va lancer les smart contrats on Goerli Testnet, on va faire quelques Swaps dans un frontend basique avec le minimum de code que tu auras besoin.

Avant de commencer

Sommaire

Cette vidéo a beaucoup de code, c'est pour ça qu'on a ajouté un sommaire.

Factory
Router
- Router Liquidity
- Router Swaps
Tokens d'example
Frontend
- JSON ABI
- HTML
- Javascript
Utiliser la web

1. La Factory

Envoie ton adresse comme paramètre dans le constructeur. Le fee setter est l'administrateur du contrat, celui-ci peut devenir un multisig o DAO.

// SPDX-License-Identifier: MIT
pragma solidity =0.5.16;

library SafeMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }
}

interface IUniswapV2ERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
}

contract UniswapV2ERC20 is IUniswapV2ERC20 {
    using SafeMath for uint;

    string public constant name = 'Uniswap V2';
    string public constant symbol = 'UNI-V2';
    uint8 public constant decimals = 18;
    uint  public totalSupply;
    mapping(address => uint) public balanceOf;
    mapping(address => mapping(address => uint)) public allowance;

    bytes32 public DOMAIN_SEPARATOR;
    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    mapping(address => uint) public nonces;

    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    constructor() public {
        uint chainId;
        assembly {
            chainId := chainid
        }
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                keccak256(bytes(name)),
                keccak256(bytes('1')),
                chainId,
                address(this)
            )
        );
    }

    function _mint(address to, uint value) internal {
        totalSupply = totalSupply.add(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(address(0), to, value);
    }

    function _burn(address from, uint value) internal {
        balanceOf[from] = balanceOf[from].sub(value);
        totalSupply = totalSupply.sub(value);
        emit Transfer(from, address(0), value);
    }

    function _approve(address owner, address spender, uint value) private {
        allowance[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    function _transfer(address from, address to, uint value) private {
        balanceOf[from] = balanceOf[from].sub(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(from, to, value);
    }

    function approve(address spender, uint value) external returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transfer(address to, uint value) external returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function transferFrom(address from, address to, uint value) external returns (bool) {
        if (allowance[from][msg.sender] != uint(-1)) {
            allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
        }
        _transfer(from, to, value);
        return true;
    }

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
        require(deadline >= block.timestamp, 'UniswapV2: EXPIRED');
        bytes32 digest = keccak256(
            abi.encodePacked(
                '\x19\x01',
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(recoveredAddress != address(0) && recoveredAddress == owner, 'UniswapV2: INVALID_SIGNATURE');
        _approve(owner, spender, value);
    }
}

library Math {
    function min(uint x, uint y) internal pure returns (uint z) {
        z = x < y ? x : y;
    }

    // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
    function sqrt(uint y) internal pure returns (uint z) {
        if (y > 3) {
            z = y;
            uint x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
    }
}

library UQ112x112 {
    uint224 constant Q112 = 2**112;

    // encode a uint112 as a UQ112x112
    function encode(uint112 y) internal pure returns (uint224 z) {
        z = uint224(y) * Q112; // never overflows
    }

    // divide a UQ112x112 by a uint112, returning a UQ112x112
    function uqdiv(uint224 x, uint112 y) internal pure returns (uint224 z) {
        z = x / uint224(y);
    }
}

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

interface IUniswapV2Callee {
    function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
}

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

contract UniswapV2Pair is IUniswapV2Pair, UniswapV2ERC20 {
    using SafeMath  for uint;
    using UQ112x112 for uint224;

    uint public constant MINIMUM_LIQUIDITY = 10**3;
    bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));

    address public factory;
    address public token0;
    address public token1;

    uint112 private reserve0;           // uses single storage slot, accessible via getReserves
    uint112 private reserve1;           // uses single storage slot, accessible via getReserves
    uint32  private blockTimestampLast; // uses single storage slot, accessible via getReserves

    uint public price0CumulativeLast;
    uint public price1CumulativeLast;
    uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event

    uint private unlocked = 1;
    modifier lock() {
        require(unlocked == 1, 'UniswapV2: LOCKED');
        unlocked = 0;
        _;
        unlocked = 1;
    }

    function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) {
        _reserve0 = reserve0;
        _reserve1 = reserve1;
        _blockTimestampLast = blockTimestampLast;
    }

    function _safeTransfer(address token, address to, uint value) private {
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'UniswapV2: TRANSFER_FAILED');
    }

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    constructor() public {
        factory = msg.sender;
    }

    // called once by the factory at time of deployment
    function initialize(address _token0, address _token1) external {
        require(msg.sender == factory, 'UniswapV2: FORBIDDEN'); // sufficient check
        token0 = _token0;
        token1 = _token1;
    }

    // update reserves and, on the first call per block, price accumulators
    function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
        require(balance0 <= uint112(-1) && balance1 <= uint112(-1), 'UniswapV2: OVERFLOW');
        uint32 blockTimestamp = uint32(block.timestamp % 2**32);
        uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
        if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
            // * never overflows, and + overflow is desired
            price0CumulativeLast += uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
            price1CumulativeLast += uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1)) * timeElapsed;
        }
        reserve0 = uint112(balance0);
        reserve1 = uint112(balance1);
        blockTimestampLast = blockTimestamp;
        emit Sync(reserve0, reserve1);
    }

    // if fee is on, mint liquidity equivalent to 1/6th of the growth in sqrt(k)
    function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
        address feeTo = IUniswapV2Factory(factory).feeTo();
        feeOn = feeTo != address(0);
        uint _kLast = kLast; // gas savings
        if (feeOn) {
            if (_kLast != 0) {
                uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
                uint rootKLast = Math.sqrt(_kLast);
                if (rootK > rootKLast) {
                    uint numerator = totalSupply.mul(rootK.sub(rootKLast));
                    uint denominator = rootK.mul(5).add(rootKLast);
                    uint liquidity = numerator / denominator;
                    if (liquidity > 0) _mint(feeTo, liquidity);
                }
            }
        } else if (_kLast != 0) {
            kLast = 0;
        }
    }

    // this low-level function should be called from a contract which performs important safety checks
    function mint(address to) external lock returns (uint liquidity) {
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        uint balance0 = IERC20(token0).balanceOf(address(this));
        uint balance1 = IERC20(token1).balanceOf(address(this));
        uint amount0 = balance0.sub(_reserve0);
        uint amount1 = balance1.sub(_reserve1);

        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        if (_totalSupply == 0) {
            liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
           _mint(address(0), MINIMUM_LIQUIDITY); // permanently lock the first MINIMUM_LIQUIDITY tokens
        } else {
            liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
        }
        require(liquidity > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_MINTED');
        _mint(to, liquidity);

        _update(balance0, balance1, _reserve0, _reserve1);
        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
        emit Mint(msg.sender, amount0, amount1);
    }

    // this low-level function should be called from a contract which performs important safety checks
    function burn(address to) external lock returns (uint amount0, uint amount1) {
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        address _token0 = token0;                                // gas savings
        address _token1 = token1;                                // gas savings
        uint balance0 = IERC20(_token0).balanceOf(address(this));
        uint balance1 = IERC20(_token1).balanceOf(address(this));
        uint liquidity = balanceOf[address(this)];

        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        amount0 = liquidity.mul(balance0) / _totalSupply; // using balances ensures pro-rata distribution
        amount1 = liquidity.mul(balance1) / _totalSupply; // using balances ensures pro-rata distribution
        require(amount0 > 0 && amount1 > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_BURNED');
        _burn(address(this), liquidity);
        _safeTransfer(_token0, to, amount0);
        _safeTransfer(_token1, to, amount1);
        balance0 = IERC20(_token0).balanceOf(address(this));
        balance1 = IERC20(_token1).balanceOf(address(this));

        _update(balance0, balance1, _reserve0, _reserve1);
        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
        emit Burn(msg.sender, amount0, amount1, to);
    }

    // this low-level function should be called from a contract which performs important safety checks
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock {
        require(amount0Out > 0 || amount1Out > 0, 'UniswapV2: INSUFFICIENT_OUTPUT_AMOUNT');
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        require(amount0Out < _reserve0 && amount1Out < _reserve1, 'UniswapV2: INSUFFICIENT_LIQUIDITY');

        uint balance0;
        uint balance1;
        { // scope for _token{0,1}, avoids stack too deep errors
        address _token0 = token0;
        address _token1 = token1;
        require(to != _token0 && to != _token1, 'UniswapV2: INVALID_TO');
        if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens
        if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens
        if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, amount0Out, amount1Out, data);
        balance0 = IERC20(_token0).balanceOf(address(this));
        balance1 = IERC20(_token1).balanceOf(address(this));
        }
        uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
        uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
        require(amount0In > 0 || amount1In > 0, 'UniswapV2: INSUFFICIENT_INPUT_AMOUNT');
        { // scope for reserve{0,1}Adjusted, avoids stack too deep errors
        uint balance0Adjusted = balance0.mul(1000).sub(amount0In.mul(3));
        uint balance1Adjusted = balance1.mul(1000).sub(amount1In.mul(3));
        require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'UniswapV2: K');
        }

        _update(balance0, balance1, _reserve0, _reserve1);
        emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
    }

    // force balances to match reserves
    function skim(address to) external lock {
        address _token0 = token0; // gas savings
        address _token1 = token1; // gas savings
        _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)).sub(reserve0));
        _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)).sub(reserve1));
    }

    // force reserves to match balances
    function sync() external lock {
        _update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
    }
}

contract UniswapV2Factory is IUniswapV2Factory {
    address public feeTo;
    address public feeToSetter;

    mapping(address => mapping(address => address)) public getPair;
    address[] public allPairs;

    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    constructor(address _feeToSetter) public {
        feeToSetter = _feeToSetter;
    }

    function allPairsLength() external view returns (uint) {
        return allPairs.length;
    }

    function createPair(address tokenA, address tokenB) external returns (address pair) {
        require(tokenA != tokenB, 'UniswapV2: IDENTICAL_ADDRESSES');
        (address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'UniswapV2: ZERO_ADDRESS');
        require(getPair[token0][token1] == address(0), 'UniswapV2: PAIR_EXISTS'); // single check is sufficient
        bytes memory bytecode = type(UniswapV2Pair).creationCode;
        bytes32 salt = keccak256(abi.encodePacked(token0, token1));
        assembly {
            pair := create2(0, add(bytecode, 32), mload(bytecode), salt)
        }
        IUniswapV2Pair(pair).initialize(token0, token1);
        getPair[token0][token1] = pair;
        getPair[token1][token0] = pair; // populate mapping in the reverse direction
        allPairs.push(pair);
        emit PairCreated(token0, token1, pair, allPairs.length);
    }

    function setFeeTo(address _feeTo) external {
        require(msg.sender == feeToSetter, 'UniswapV2: FORBIDDEN');
        feeTo = _feeTo;
    }

    function setFeeToSetter(address _feeToSetter) external {
        require(msg.sender == feeToSetter, 'UniswapV2: FORBIDDEN');
        feeToSetter = _feeToSetter;
    }
}

2. El Router

2.1 El RouterLiquidity

Envoie l'adresse du factory et de WETH comme paramètre. L'adresse de WETH va dépendre du network, en Mainnet c'est 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 et en Goerli 0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6.

// SPDX-License-Identifier: MIT
pragma solidity =0.6.6;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

library TransferHelper {
    function safeApprove(
        address token,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('approve(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::safeApprove: approve failed'
        );
    }

    function safeTransfer(
        address token,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('transfer(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::safeTransfer: transfer failed'
        );
    }

    function safeTransferFrom(
        address token,
        address from,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::transferFrom: transferFrom failed'
        );
    }

    function safeTransferETH(address to, uint256 value) internal {
        (bool success, ) = to.call{value: value}(new bytes(0));
        require(success, 'TransferHelper::safeTransferETH: ETH transfer failed');
    }
}

interface IUniswapV2Router01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);
}

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

library SafeMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }
}

library UniswapV2Library {
    using SafeMath for uint;

    // returns sorted token addresses, used to handle return values from pairs sorted in this order
    function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {
        require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');
        (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');
    }

    // fetches and sorts the reserves for a pair
    function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {
        (address token0,) = sortTokens(tokenA, tokenB);
        (uint reserve0, uint reserve1,) = IUniswapV2Pair(IUniswapV2Factory(factory).getPair(tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }

    // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
    function quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {
        require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');
        require(reserveA > 0 && reserveB > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        amountB = amountA.mul(reserveB) / reserveA;
    }

    // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) internal pure returns (uint amountOut) {
        require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint amountInWithFee = amountIn.mul(997);
        uint numerator = amountInWithFee.mul(reserveOut);
        uint denominator = reserveIn.mul(1000).add(amountInWithFee);
        amountOut = numerator / denominator;
    }

    // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) internal pure returns (uint amountIn) {
        require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint numerator = reserveIn.mul(amountOut).mul(1000);
        uint denominator = reserveOut.sub(amountOut).mul(997);
        amountIn = (numerator / denominator).add(1);
    }

    // performs chained getAmountOut calculations on any number of pairs
    function getAmountsOut(address factory, uint amountIn, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[0] = amountIn;
        for (uint i; i < path.length - 1; i++) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1]);
            amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
        }
    }

    // performs chained getAmountIn calculations on any number of pairs
    function getAmountsIn(address factory, uint amountOut, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[amounts.length - 1] = amountOut;
        for (uint i = path.length - 1; i > 0; i--) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i]);
            amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
        }
    }
}

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

interface IWETH {
    function deposit() external payable;
    function transfer(address to, uint value) external returns (bool);
    function withdraw(uint) external;
}

contract UniswapV2Router02Liquidity is IUniswapV2Router02 {
    using SafeMath for uint;

    address public immutable override factory;
    address public immutable override WETH;

    modifier ensure(uint deadline) {
        require(deadline >= block.timestamp, 'UniswapV2Router: EXPIRED');
        _;
    }

    constructor(address _factory, address _WETH) public {
        factory = _factory;
        WETH = _WETH;
    }

    receive() external payable {
        assert(msg.sender == WETH); // only accept ETH via fallback from the WETH contract
    }

    // **** ADD LIQUIDITY ****
    function _addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin
    ) internal virtual returns (uint amountA, uint amountB) {
        // create the pair if it doesn't exist yet
        if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {
            IUniswapV2Factory(factory).createPair(tokenA, tokenB);
        }
        (uint reserveA, uint reserveB) = UniswapV2Library.getReserves(factory, tokenA, tokenB);
        if (reserveA == 0 && reserveB == 0) {
            (amountA, amountB) = (amountADesired, amountBDesired);
        } else {
            uint amountBOptimal = UniswapV2Library.quote(amountADesired, reserveA, reserveB);
            if (amountBOptimal <= amountBDesired) {
                require(amountBOptimal >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
                (amountA, amountB) = (amountADesired, amountBOptimal);
            } else {
                uint amountAOptimal = UniswapV2Library.quote(amountBDesired, reserveB, reserveA);
                assert(amountAOptimal <= amountADesired);
                require(amountAOptimal >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
                (amountA, amountB) = (amountAOptimal, amountBDesired);
            }
        }
    }
    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {
        (amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);
        address pair = IUniswapV2Factory(factory).getPair(tokenA, tokenB);
        TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
        TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
        liquidity = IUniswapV2Pair(pair).mint(to);
    }
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external virtual override payable ensure(deadline) returns (uint amountToken, uint amountETH, uint liquidity) {
        (amountToken, amountETH) = _addLiquidity(
            token,
            WETH,
            amountTokenDesired,
            msg.value,
            amountTokenMin,
            amountETHMin
        );
        address pair = IUniswapV2Factory(factory).getPair(token, WETH);
        TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);
        IWETH(WETH).deposit{value: amountETH}();
        assert(IWETH(WETH).transfer(pair, amountETH));
        liquidity = IUniswapV2Pair(pair).mint(to);
        // refund dust eth, if any
        if (msg.value > amountETH) TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH);
    }

    // **** REMOVE LIQUIDITY ****
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountA, uint amountB) {
        address pair = IUniswapV2Factory(factory).getPair(tokenA, tokenB);
        IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity); // send liquidity to pair
        (uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(to);
        (address token0,) = UniswapV2Library.sortTokens(tokenA, tokenB);
        (amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);
        require(amountA >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
        require(amountB >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
    }
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountToken, uint amountETH) {
        (amountToken, amountETH) = removeLiquidity(
            token,
            WETH,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(token, to, amountToken);
        IWETH(WETH).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountA, uint amountB) {
        address pair = IUniswapV2Factory(factory).getPair(tokenA, tokenB);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);
    }
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountToken, uint amountETH) {
        address pair = IUniswapV2Factory(factory).getPair(token, WETH);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountToken, amountETH) = removeLiquidityETH(token, liquidity, amountTokenMin, amountETHMin, to, deadline);
    }

    // **** REMOVE LIQUIDITY (supporting fee-on-transfer tokens) ****
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountETH) {
        (, amountETH) = removeLiquidity(
            token,
            WETH,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(token, to, IERC20(token).balanceOf(address(this)));
        IWETH(WETH).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountETH) {
        address pair = IUniswapV2Factory(factory).getPair(token, WETH);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        amountETH = removeLiquidityETHSupportingFeeOnTransferTokens(
            token, liquidity, amountTokenMin, amountETHMin, to, deadline
        );
    }

    // **** LIBRARY FUNCTIONS ****
    function quote(uint amountA, uint reserveA, uint reserveB) public pure virtual override returns (uint amountB) {
        return UniswapV2Library.quote(amountA, reserveA, reserveB);
    }

    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut)
        public
        pure
        virtual
        override
        returns (uint amountOut)
    {
        return UniswapV2Library.getAmountOut(amountIn, reserveIn, reserveOut);
    }

    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut)
        public
        pure
        virtual
        override
        returns (uint amountIn)
    {
        return UniswapV2Library.getAmountIn(amountOut, reserveIn, reserveOut);
    }

    function getAmountsOut(uint amountIn, address[] memory path)
        public
        view
        virtual
        override
        returns (uint[] memory amounts)
    {
        return UniswapV2Library.getAmountsOut(factory, amountIn, path);
    }

    function getAmountsIn(uint amountOut, address[] memory path)
        public
        view
        virtual
        override
        returns (uint[] memory amounts)
    {
        return UniswapV2Library.getAmountsIn(factory, amountOut, path);
    }
}

2.2 Le RouterSwaps

Le RouterSwaps utilise les mêmes paramètres que le RouterLiquidity. Envoie lui comme paramètres l'adresse du factory qu'on vient de lancer et aussi l'adresse du WETH. L'addresse du WETH va dépendre du network que tu es en train d'utiliser, en Mainnet c'est 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 et on Goerli 0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6.

// SPDX-License-Identifier: MIT
pragma solidity =0.6.6;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

library TransferHelper {
    function safeApprove(
        address token,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('approve(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::safeApprove: approve failed'
        );
    }

    function safeTransfer(
        address token,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('transfer(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::safeTransfer: transfer failed'
        );
    }

    function safeTransferFrom(
        address token,
        address from,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::transferFrom: transferFrom failed'
        );
    }

    function safeTransferETH(address to, uint256 value) internal {
        (bool success, ) = to.call{value: value}(new bytes(0));
        require(success, 'TransferHelper::safeTransferETH: ETH transfer failed');
    }
}

interface IUniswapV2Router01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

interface IUniswapV2Router02 is IUniswapV2Router01 {

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

library SafeMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }
}

library UniswapV2Library {
    using SafeMath for uint;

    // returns sorted token addresses, used to handle return values from pairs sorted in this order
    function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {
        require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');
        (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');
    }

    // fetches and sorts the reserves for a pair
    function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {
        (address token0,) = sortTokens(tokenA, tokenB);
        (uint reserve0, uint reserve1,) = IUniswapV2Pair(IUniswapV2Factory(factory).getPair(tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }

    // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
    function quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {
        require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');
        require(reserveA > 0 && reserveB > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        amountB = amountA.mul(reserveB) / reserveA;
    }

    // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) internal pure returns (uint amountOut) {
        require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint amountInWithFee = amountIn.mul(997);
        uint numerator = amountInWithFee.mul(reserveOut);
        uint denominator = reserveIn.mul(1000).add(amountInWithFee);
        amountOut = numerator / denominator;
    }

    // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) internal pure returns (uint amountIn) {
        require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint numerator = reserveIn.mul(amountOut).mul(1000);
        uint denominator = reserveOut.sub(amountOut).mul(997);
        amountIn = (numerator / denominator).add(1);
    }

    // performs chained getAmountOut calculations on any number of pairs
    function getAmountsOut(address factory, uint amountIn, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[0] = amountIn;
        for (uint i; i < path.length - 1; i++) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1]);
            amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
        }
    }

    // performs chained getAmountIn calculations on any number of pairs
    function getAmountsIn(address factory, uint amountOut, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[amounts.length - 1] = amountOut;
        for (uint i = path.length - 1; i > 0; i--) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i]);
            amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
        }
    }
}

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

interface IWETH {
    function deposit() external payable;
    function transfer(address to, uint value) external returns (bool);
    function withdraw(uint) external;
}

contract UniswapV2Router02Swaps is IUniswapV2Router02 {
    using SafeMath for uint;

    address public immutable override factory;
    address public immutable override WETH;

    modifier ensure(uint deadline) {
        require(deadline >= block.timestamp, 'UniswapV2Router: EXPIRED');
        _;
    }

    constructor(address _factory, address _WETH) public {
        factory = _factory;
        WETH = _WETH;
    }

    receive() external payable {
        assert(msg.sender == WETH); // only accept ETH via fallback from the WETH contract
    }

    // **** SWAP ****
    // requires the initial amount to have already been sent to the first pair
    function _swap(uint[] memory amounts, address[] memory path, address _to) internal virtual {
        for (uint i; i < path.length - 1; i++) {
            (address input, address output) = (path[i], path[i + 1]);
            (address token0,) = UniswapV2Library.sortTokens(input, output);
            uint amountOut = amounts[i + 1];
            (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOut) : (amountOut, uint(0));
            address to = i < path.length - 2 ? IUniswapV2Factory(factory).getPair(output, path[i + 2]) : _to;
            IUniswapV2Pair(IUniswapV2Factory(factory).getPair(input, output)).swap(
                amount0Out, amount1Out, to, new bytes(0)
            );
        }
    }

    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint[] memory amounts) {
        amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, IUniswapV2Factory(factory).getPair(path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, to);
    }
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint[] memory amounts) {
        amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, IUniswapV2Factory(factory).getPair(path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, to);
    }
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        payable
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsOut(factory, msg.value, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        IWETH(WETH).deposit{value: amounts[0]}();
        assert(IWETH(WETH).transfer(IUniswapV2Factory(factory).getPair(path[0], path[1]), amounts[0]));
        _swap(amounts, path, to);
    }
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, IUniswapV2Factory(factory).getPair(path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, IUniswapV2Factory(factory).getPair(path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        payable
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= msg.value, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
        IWETH(WETH).deposit{value: amounts[0]}();
        assert(IWETH(WETH).transfer(IUniswapV2Factory(factory).getPair(path[0], path[1]), amounts[0]));
        _swap(amounts, path, to);
        // refund dust eth, if any
        if (msg.value > amounts[0]) TransferHelper.safeTransferETH(msg.sender, msg.value - amounts[0]);
    }

    // **** SWAP (supporting fee-on-transfer tokens) ****
    // requires the initial amount to have already been sent to the first pair
    function _swapSupportingFeeOnTransferTokens(address[] memory path, address _to) internal virtual {
        for (uint i; i < path.length - 1; i++) {
            (address input, address output) = (path[i], path[i + 1]);
            (address token0,) = UniswapV2Library.sortTokens(input, output);
            IUniswapV2Pair pair = IUniswapV2Pair(IUniswapV2Factory(factory).getPair(input, output));
            uint amountInput;
            uint amountOutput;
            { // scope to avoid stack too deep errors
            (uint reserve0, uint reserve1,) = pair.getReserves();
            (uint reserveInput, uint reserveOutput) = input == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
            amountInput = IERC20(input).balanceOf(address(pair)).sub(reserveInput);
            amountOutput = UniswapV2Library.getAmountOut(amountInput, reserveInput, reserveOutput);
            }
            (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOutput) : (amountOutput, uint(0));
            address to = i < path.length - 2 ? IUniswapV2Factory(factory).getPair(output, path[i + 2]) : _to;
            pair.swap(amount0Out, amount1Out, to, new bytes(0));
        }
    }
    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) {
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, IUniswapV2Factory(factory).getPair(path[0], path[1]), amountIn
        );
        uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(path, to);
        require(
            IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
            'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT'
        );
    }
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    )
        external
        virtual
        override
        payable
        ensure(deadline)
    {
        require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
        uint amountIn = msg.value;
        IWETH(WETH).deposit{value: amountIn}();
        assert(IWETH(WETH).transfer(IUniswapV2Factory(factory).getPair(path[0], path[1]), amountIn));
        uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(path, to);
        require(
            IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
            'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT'
        );
    }
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    )
        external
        virtual
        override
        ensure(deadline)
    {
        require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, IUniswapV2Factory(factory).getPair(path[0], path[1]), amountIn
        );
        _swapSupportingFeeOnTransferTokens(path, address(this));
        uint amountOut = IERC20(WETH).balanceOf(address(this));
        require(amountOut >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        IWETH(WETH).withdraw(amountOut);
        TransferHelper.safeTransferETH(to, amountOut);
    }

    // **** LIBRARY FUNCTIONS ****
    function quote(uint amountA, uint reserveA, uint reserveB) public pure virtual override returns (uint amountB) {
        return UniswapV2Library.quote(amountA, reserveA, reserveB);
    }

    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut)
        public
        pure
        virtual
        override
        returns (uint amountOut)
    {
        return UniswapV2Library.getAmountOut(amountIn, reserveIn, reserveOut);
    }

    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut)
        public
        pure
        virtual
        override
        returns (uint amountIn)
    {
        return UniswapV2Library.getAmountIn(amountOut, reserveIn, reserveOut);
    }

    function getAmountsOut(uint amountIn, address[] memory path)
        public
        view
        virtual
        override
        returns (uint[] memory amounts)
    {
        return UniswapV2Library.getAmountsOut(factory, amountIn, path);
    }

    function getAmountsIn(uint amountOut, address[] memory path)
        public
        view
        virtual
        override
        returns (uint[] memory amounts)
    {
        return UniswapV2Library.getAmountsIn(factory, amountOut, path);
    }
}

3. Tokens examples

Lance quelques tokens qui vont nous aider à essayer comment ajouter de liquidité et faire des swaps.

// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract SimpleToken is ERC20 {
    constructor(
        string memory name,
        string memory symbol,
        uint256 initialSupply
    ) ERC20(name, symbol) {
        _mint(msg.sender, initialSupply * 1 ether);
    }
}

4. Le Frontend

El JSON ABI

Crée un dossier json_abi/ et mets dans le JSON ABIs suivants que tu peux trouver dans remix après avoir compilé.

* json_abi/
  - ERC20.json
  - Factory.json
  - Pair.json
  - RouterLiquidity.json
  - RouterSwaps.json

L'HTML

L'HTML décrit l'interface que nos aide à essayer avec les contrats.

index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
</head>
<body>
  <input id="connect_button" type="button" value="Connect" onclick="connectWallet()" style="display: none"></input>
  <p id="account_address" style="display: none"></p>
  <p id="web3_message"></p>
  <p id="contract_state"></p>
  <h1>Liquidity</h1>

  <p>Approve TokenA</p>
  <input type="input"  value="" id="approveTokenAAmountLiquidity"></input><br>
  <input type="button" value="approve" onclick="_approveTokenALiquidity()"></input><br><br>

  <p>Approve TokenB</p>
  <input type="input"  value="" id="approveTokenBAmountLiquidity"></input><br>
  <input type="button" value="approve" onclick="_approveTokenBLiquidity()"></input><br><br>

  <p>Add liquidity (ERC20)</p>
  <input type="input"  value="" id="amountADesired"></input><br>
  <input type="input"  value="" id="amountBDesired"></input><br>
  <input type="button" value="Add liquidity" onclick="_addLiquidity()"></input><br><br>

  <h1>Swap</h1>

  <h2>From TokenA</h2>

  <p id="tokenAPrice"></p>

  <p>Approve TokenA</p>
  <input type="input"  value="" id="approveTokenASwapsAmount"></input><br>
  <input type="button" value="approve" onclick="_approveTokenASwaps()"></input><br><br>

  <p>To TokenB</p>
  <input type="input"  value="" id="amountInTokenAForTokenB"></input><br>
  <input type="button" value="swap" onclick="_swapExactTokensForTokensTokenAForTokenB()"></input><br><br>

  <h2>From TokenB</h2>

  <p id="tokenBPrice"></p>

  <p>Approve TokenB</p>
  <input type="input"  value="" id="approveTokenBSwapsAmount"></input><br>
  <input type="button" value="approve" onclick="_approveTokenBSwaps()"></input><br><br>

  <p>To TokenA</p>
  <input type="input"  value="" id="amountInTokenBForTokenA"></input><br>
  <input type="button" value="swap" onclick="_swapExactTokensForTokensTokenBForTokenA()"></input><br><br>

  <br>
  <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/web3/1.3.5/web3.min.js"></script>
  <script type="text/javascript" src="blockchain_stuff.js"></script>
</body>
</html>

<script>
  function _approveTokenALiquidity()
  {
    approveTokenAAmountLiquidity = document.getElementById("approveTokenAAmountLiquidity").value
    approveTokenALiquidity(approveTokenAAmountLiquidity)
  }

  function _approveTokenBLiquidity()
  {
    approveTokenBAmountLiquidity = document.getElementById("approveTokenBAmountLiquidity").value
    approveTokenBLiquidity(approveTokenBAmountLiquidity)
  }

  function _addLiquidity()
  {
    amountADesired = document.getElementById("amountADesired").value
    amountBDesired = document.getElementById("amountBDesired").value
    addLiquidity(amountADesired, amountBDesired)
  }

  function _approveTokenASwaps()
  {
    approveTokenAAmount = document.getElementById("approveTokenASwapsAmount").value
    approveTokenASwaps(approveTokenAAmount)
  }

  function _approveTokenBSwaps()
  {
    approveTokenBAmount = document.getElementById("approveTokenBSwapsAmount").value
    approveTokenBSwaps(approveTokenBAmount)
  }

  function _swapExactTokensForTokensTokenAForTokenB()
  {
    amountIn = document.getElementById("amountInTokenAForTokenB").value
    swapExactTokensForTokensTokenAForTokenB(amountIn)
  }

  function _swapExactTokensForTokensTokenBForTokenA()
  {
    amountIn = document.getElementById("amountInTokenBForTokenA").value
    swapExactTokensForTokensTokenBForTokenA(amountIn)
  }
</script>

El Javascript

blockchain_stuff.js

const NETWORK_ID = 5

const FACTORY_ADDRESS =             "0xBa618dD3502DD8a169Cfc368eC8d2145c958E4FB"
const ROUTER_LIQUIDITY_ADDRESS =    "0x185eb3950885528925313F19c49BAc43547e4ab8"
const ROUTER_SWAPS_ADDRESS =        "0x8b0b4A71eE0647DcBeeaf592Dd08c93BD75bEa8e"
const TOKENA_ADDRESS =              "0x348a26Dbd2A3B5DB4042f66b2caF7aEE4931A181"
const TOKENB_ADDRESS =              "0xaCACaDa2efA5c9EB8dDEE169535afe4f2790c54F"

var PAIR_ADDRESS =                ""

const FACTORY_ABI_PATH =            "./json_abi/Factory.json"
const PAIR_ABI_PATH =               "./json_abi/Pair.json"
const ROUTER_SWAPS_ABI_PATH =       "./json_abi/RouterSwaps.json"
const ROUTER_LIQUIDITY_ABI_PATH =   "./json_abi/RouterLiquidity.json"
const ERC20_ABI_PATH =              "./json_abi/ERC20.json"

var factoryContract
var pairContract
var routerSwapsContract
var routerLiquidityContract
var tokenAContract
var tokenBContract

var accounts
var web3

function metamaskReloadCallback() {
  window.ethereum.on('accountsChanged', (accounts) => {
    document.getElementById("web3_message").textContent="Se cambió el account, refrescando...";
    window.location.reload()
  })
  window.ethereum.on('networkChanged', (accounts) => {
    document.getElementById("web3_message").textContent="Se el network, refrescando...";
    window.location.reload()
  })
}

const getWeb3 = async () => {
  return new Promise((resolve, reject) => {
    if(document.readyState=="complete")
    {
      if (window.ethereum) {
        const web3 = new Web3(window.ethereum)
        window.location.reload()
        resolve(web3)
      } else {
        reject("must install MetaMask")
        document.getElementById("web3_message").textContent="Error: Please connect to Metamask";
      }
    }else
    {
      window.addEventListener("load", async () => {
        if (window.ethereum) {
          const web3 = new Web3(window.ethereum)
          resolve(web3)
        } else {
          reject("must install MetaMask")
          document.getElementById("web3_message").textContent="Error: Please install Metamask";
        }
      });
    }
  });
};

const getContract = async (web3, address, abi_path) => {
  const response = await fetch(abi_path);
  const data = await response.json();

  const netId = await web3.eth.net.getId();
  contract = new web3.eth.Contract(
    data,
    address
    );
  return contract
}

async function loadDapp() {
  metamaskReloadCallback()
  document.getElementById("web3_message").textContent="Please connect to Metamask"
  var awaitWeb3 = async function () {
    web3 = await getWeb3()
    web3.eth.net.getId((err, netId) => {
      if (netId == NETWORK_ID) {
        var awaitContract = async function () {
          factoryContract = await getContract(web3, FACTORY_ADDRESS, FACTORY_ABI_PATH)
          PAIR_ADDRESS = await factoryContract.methods.getPair(TOKENA_ADDRESS, TOKENB_ADDRESS).call()
          pairContract = await getContract(web3, PAIR_ADDRESS, PAIR_ABI_PATH)
          routerSwapsContract = await getContract(web3, ROUTER_SWAPS_ADDRESS, ROUTER_SWAPS_ABI_PATH)
          routerLiquidityContract = await getContract(web3, ROUTER_LIQUIDITY_ADDRESS, ROUTER_LIQUIDITY_ABI_PATH)
          tokenAContract = await getContract(web3, TOKENA_ADDRESS, ERC20_ABI_PATH)
          tokenBContract = await getContract(web3, TOKENB_ADDRESS, ERC20_ABI_PATH)
          document.getElementById("web3_message").textContent="You are connected to Metamask"
          onContractInitCallback()
          web3.eth.getAccounts(function(err, _accounts){
            accounts = _accounts
            if (err != null)
            {
              console.error("An error occurred: "+err)
            } else if (accounts.length > 0)
            {
              onWalletConnectedCallback()
              document.getElementById("account_address").style.display = "block"
            } else
            {
              document.getElementById("connect_button").style.display = "block"
            }
          });
        };
        awaitContract();
      } else {
        document.getElementById("web3_message").textContent="Please connect to Goerli";
      }
    });
  };
  awaitWeb3();
}

async function connectWallet() {
  await window.ethereum.request({ method: "eth_requestAccounts" })
  accounts = await web3.eth.getAccounts()
  onWalletConnectedCallback()
}

loadDapp()

const onContractInitCallback = async () => {
  if(PAIR_ADDRESS != "0x0000000000000000000000000000000000000000")
  {
    reserves = await pairContract.methods.getReserves().call()
    reserve0 = reserves._reserve0
    reserve1 = reserves._reserve1

    console.log(reserves)
    console.log(reserve0)
    console.log(reserve1)

    if(reserve0 == TOKENA_ADDRESS)
    {
      tokenAPrice = "1 TokenA = " + (reserve0/reserve1) + " TokenB"
      tokenBPrice = "1 TokenB = " + (reserve1/reserve0) + " TokenA"
    }else
    {
      tokenAPrice = "1 TokenA = " + (reserve1/reserve0) + " TokenB"
      tokenBPrice = "1 TokenB = " + (reserve0/reserve1) + " TokenA"
    }

    document.getElementById("tokenAPrice").textContent= tokenAPrice;
    document.getElementById("tokenBPrice").textContent= tokenBPrice;
  }else
  {
    document.getElementById("tokenAPrice").textContent= "Can't swap: Please add liquidity";
    document.getElementById("tokenBPrice").textContent= "Can't swap: Please add liquidity";
  }
}

const onWalletConnectedCallback = async () => {
  var balanceTokenA = await tokenAContract.methods.balanceOf(accounts[0]).call()
  var balanceTokenB = await tokenBContract.methods.balanceOf(accounts[0]).call()

  var contract_state = ""
  contract_state += "You have: " + web3.utils.fromWei(balanceTokenA) + " " + await tokenAContract.methods.symbol().call()
  contract_state += ", " + web3.utils.fromWei(balanceTokenB) + " " + await tokenBContract.methods.symbol().call()

  document.getElementById("contract_state").textContent = contract_state;
}


//// Functions ////

const approveTokenALiquidity = async (amount) => {
  const result = await tokenAContract.methods.approve(ROUTER_LIQUIDITY_ADDRESS, web3.utils.toWei(amount))
  .send({ from: accounts[0], gas: 0, value: 0 })
  .on('transactionHash', function(hash){
    document.getElementById("web3_message").textContent="Executing...";
  })
  .on('receipt', function(receipt){
    document.getElementById("web3_message").textContent="Success.";    })
  .catch((revertReason) => {
    console.log("ERROR! Transaction reverted: " + revertReason.receipt.transactionHash)
  });
}

const approveTokenBLiquidity = async (amount) => {
  const result = await tokenBContract.methods.approve(ROUTER_LIQUIDITY_ADDRESS, web3.utils.toWei(amount))
  .send({ from: accounts[0], gas: 0, value: 0 })
  .on('transactionHash', function(hash){
    document.getElementById("web3_message").textContent="Executing...";
  })
  .on('receipt', function(receipt){
    document.getElementById("web3_message").textContent="Success.";    })
  .catch((revertReason) => {
    console.log("ERROR! Transaction reverted: " + revertReason.receipt.transactionHash)
  });
}

const addLiquidity = async (amountADesired, amountBDesired) => {

  const deadline = Math.round(Date.now() / 1000) + 60

  const result = await routerLiquidityContract.methods.addLiquidity(
    TOKENA_ADDRESS,
    TOKENB_ADDRESS,
    web3.utils.toWei(amountADesired),
    web3.utils.toWei(amountBDesired),
    web3.utils.toWei("0"),
    web3.utils.toWei("0"),
    accounts[0],
    deadline
  ).send({ from: accounts[0], value: 0 })
  .on('transactionHash', function(hash){
    document.getElementById("web3_message").textContent="Executing...";
  })
  .on('receipt', function(receipt){
    document.getElementById("web3_message").textContent="Success.";    })
  .catch((revertReason) => {
    console.log("ERROR! Transaction reverted: " + revertReason.receipt.transactionHash)
  });
}

const approveTokenASwaps = async (amount) => {
  const result = await tokenAContract.methods.approve(ROUTER_SWAPS_ADDRESS, web3.utils.toWei(amount))
  .send({ from: accounts[0], gas: 0, value: 0 })
  .on('transactionHash', function(hash){
    document.getElementById("web3_message").textContent="Executing...";
  })
  .on('receipt', function(receipt){
    document.getElementById("web3_message").textContent="Success.";    })
  .catch((revertReason) => {
    console.log("ERROR! Transaction reverted: " + revertReason.receipt.transactionHash)
  });
}

const approveTokenBSwaps = async (amount) => {
  const result = await tokenBContract.methods.approve(ROUTER_SWAPS_ADDRESS, web3.utils.toWei(amount))
  .send({ from: accounts[0], gas: 0, value: 0 })
  .on('transactionHash', function(hash){
    document.getElementById("web3_message").textContent="Executing...";
  })
  .on('receipt', function(receipt){
    document.getElementById("web3_message").textContent="Success.";    })
  .catch((revertReason) => {
    console.log("ERROR! Transaction reverted: " + revertReason.receipt.transactionHash)
  });
}

const swapExactTokensForTokensTokenAForTokenB = async (amountIn) => {
  const deadline = Math.round(Date.now() / 1000) + 60

  const result = await routerSwapsContract.methods.swapExactTokensForTokens(
    web3.utils.toWei(amountIn),
    0,
    [TOKENA_ADDRESS, TOKENB_ADDRESS],
    accounts[0],
    deadline
  ).send({ from: accounts[0], gas: 0, value: 0 })
  .on('transactionHash', function(hash){
    document.getElementById("web3_message").textContent="Executing...";
  })
  .on('receipt', function(receipt){
    document.getElementById("web3_message").textContent="Success.";    })
  .catch((revertReason) => {
    console.log("ERROR! Transaction reverted: " + revertReason.receipt.transactionHash)
  });
}

const swapExactTokensForTokensTokenBForTokenA = async (amountIn) => {
  const deadline = Math.round(Date.now() / 1000) + 60

  const result = await routerSwapsContract.methods.swapExactTokensForTokens(
    web3.utils.toWei(amountIn),
    0,
    [TOKENB_ADDRESS, TOKENA_ADDRESS],
    accounts[0],
    deadline
  ).send({ from: accounts[0], gas: 0, value: 0 })
  .on('transactionHash', function(hash){
    document.getElementById("web3_message").textContent="Executing...";
  })
  .on('receipt', function(receipt){
    document.getElementById("web3_message").textContent="Success.";    })
  .catch((revertReason) => {
    console.log("ERROR! Transaction reverted: " + revertReason.receipt.transactionHash)
  });
}

5. Essayer la web

npm install -g lite-server
lite-server

Tu peux trouver le résultat en http://localhost:3000.

Maintenant tu peux ajouter la liquidité et commenr a faire des swaps. Rapelez vous que tu doit aprover le RouterLiquidity et le RouterSwaps séparément.

¡Merci pour voir cette video!

Suivez nous ici en dev.to et en Youtube pour tout ce qui a à voir avec Blockchain en Francais.

J'ai fait un Token avec de Fees sur Balancer

Ahmed Castro — Thu, 20 Oct 2022 18:17:16 +0000

Balancer c'est un projet qui est en train d'innover en DeFi. J'aime bien balancer parce qu'il permet aux investisseurs obtenir un revenu passif en ses portfolios personnalisé, il permet aux traders faire des swaps payant moins de gas fees et protégés contre des attaques MEV, aussi des possibilités d'arbitrage entre d'autres choses. De plus, il a une UI es des smart contrats très modernes.

Dans cette vidéo on va lancer un token qui prend des fees dans chaque transaction dans les pools de Balancer.

Avant de commencer

Pour ce video tu auras besoin de Metamask ou n'importe quel wallet compatible avec l'EVM et aussi du GoerliETH que tu peux trouver gratuitement en un faucet.

Smart contrats avec des fees de transaction en Balancer

// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address to, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

interface IERC20Metadata is IERC20 {
    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
}

contract BalancerToken is Context, IERC20, IERC20Metadata {
    // Openzeppelin variables
    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    // My variables
    address public balancerVault = 0xBA12222222228d8Ba445958a75a0704d566BF2C8;
    address public feeWallet;

    uint public _feeDecimal = 2;
    // index 0 = buy fee, index 1 = sell fee, index 2 = p2p fee
    uint[] public fees;

    mapping(address => bool) public isTaxless;
    // Openzeppelin functions

    constructor() {
        _name = "My Balancer Token";
        _symbol = "BT";

        feeWallet = 0x0000000000000000000000000000000000000000;

        fees.push(100); // 1% buy fee
        fees.push(200); // 2% sell fee
        fees.push(0);   // 0% p2p fee

        isTaxless[msg.sender] = true;
        isTaxless[address(this)] = true;
        isTaxless[feeWallet] = true;
        isTaxless[address(0)] = true;

        _mint(msg.sender, 1_000_000 ether);
    }

    function name() public view virtual override returns (string memory) {
        return _name;
    }

    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }

    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, _allowances[owner][spender] + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = _allowances[owner][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        // My implementation
        uint256 feesCollected;
        if (!isTaxless[from] && !isTaxless[to]) {
            bool sell = to == balancerVault;
            bool p2p = from != balancerVault && to != balancerVault;
            uint feeIndex = p2p ? 2 : sell ? 1 : 0;
            feesCollected = (amount * fees[feeIndex]) / (10**(_feeDecimal + 2));
        }

        amount -= feesCollected;
        _balances[from] -= feesCollected;
        _balances[feeWallet] += feesCollected;
        // End my implementation

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
        }
        _balances[to] += amount;

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, amount);
    }

    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), account, amount);
    }

    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
        }
        _totalSupply -= amount;

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), amount);
    }

    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}

    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

¡Merci pour voir ce video!

Suivez nous ici en dev.to et en Youtube pour tout ce qui a à voir avec Blockchain en Francais.

Claimez sans Staker

Ahmed Castro — Mon, 12 Sep 2022 18:02:50 +0000

A l'époque de ce qu'on appelait DeFi 2.0 on avait du staking autocompund et des tokens avec des réflections. Ce concept peut aussi exister avec les NFTs. En ce video on va déployer des NFTs que contrôlent l'inflation d'un Token. Les holders peuvent gonfler un token sans avoir besoin de staker les NFTs, les nouvelles tokens vont être mintés directement sur notre wallet.

https://www.youtube.com/watch?v=UxuszsqYYZQ

Avant de commencer

Pour ce video tu auras besoin de Metamask ou n'importe quel wallet compatible avec l'EVM et aussi du GoerliETH que tu peux trouver gratuitement en un faucet.

Les NFTs

D'abord on lance un contrat d'NFTs, remarquez la funcion registre que fait tout ça posible.

// SPDX-License-Identifier: MIT
pragma solidity 0.8.16;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

interface ITokenContract
{
    function register(uint tokenId) external;
}

contract NFTContract is ERC721, Ownable {  
    ITokenContract tokenContract;

    uint public price = 0.001 ether;
    uint public constant MAX_SUPPLY = 10000;
    uint public supply;

    constructor () ERC721 ("My NFT", "MNFT") {
    }

    function mint(uint _amount) public payable {
        require( supply + _amount <= MAX_SUPPLY, "Can't mint more than max supply" );
        require( msg.value == price * _amount, "Wrong amount of ETH sent" );
        require( _amount >= 1, "Must mint at least one" );
        for(uint i; i < _amount; i++){
            _safeMint( msg.sender, supply + i );
            tokenContract.register(supply + i);
        }
    }

    function withdrawETH() public onlyOwner
    {
        (bool sent, bytes memory data) = address(owner()).call{value: address(this).balance}("");
        require(sent, "Failed to send Ether");
        data;
    }

    function setTokenContract(address tokenContractAddress) public onlyOwner {
        tokenContract = ITokenContract(tokenContractAddress);
    }
}

Les Tokens

Le même contrat de tokens distribue les récompenses aux holders. Tout de suite avoir déployé le contrat des tokens exécutez la function setTokenContract dans le contrat d'NFTs et passez comme paramètre l'adresse du contrat de tokens.

// SPDX-License-Identifier: MIT
pragma solidity 0.8.16;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

interface INFTContract
{
    function ownerOf(uint tokenId) external view returns (address owner);
}

contract TokenContract is ERC20, Ownable {
    uint public REWARD_PER_BLOCK = 0.1 ether;

    INFTContract public myERC721Contract;

    mapping(uint => uint) public checkpoints;
    mapping(uint => bool) public isRegistered;

    constructor(address nftContractAddress) ERC20("My Token", "TKN") {
        myERC721Contract = INFTContract(nftContractAddress);
    }

    function register(uint tokenId) public
    {
        require(msg.sender == address(myERC721Contract));
        isRegistered[tokenId] = true;
        checkpoints[tokenId] = block.number;
    }

    function claim(uint tokenId) public
    {
        require(myERC721Contract.ownerOf(tokenId) == msg.sender, "Must be token owner");
        uint256 reward = calculateReward(tokenId);
        _mint(msg.sender, reward);
        checkpoints[tokenId] = block.number;
    }

    function calculateReward(uint tokenId) public view returns(uint256)
    {
        if(!isRegistered[tokenId])
        {
            return 0;
        }
        uint256 checkpoint = checkpoints[tokenId];
        return REWARD_PER_BLOCK * (block.number-checkpoint);
    }
}

¡Merci pour voir ce video!

Suivez nous ici en dev.to et en Youtube pour tout ce qui a à voir avec Blockchain en Francais.

L'Attaque du Sandwich

Ahmed Castro — Thu, 25 Aug 2022 16:00:35 +0000

Le MEV (éxtraction de valeur pour les mineurs) est un problème qu'existe en PoW (preuve de travail) comme en PoS (preuve de staking). Le MEV donne une avantage aux mineurs sur les autres utilisateurs du blockchain. On veux pas ça. C'est pour ça qu'il y a différentes manières de le combattre comme flash bots ou même des idées a niveau du protocol. Malheureusement ce problème persiste et c'est mieux de l'attaquer depuis différentes angles. En ce vidéo on montre comment on peut prévenir un des attaques plus connues: L'attaque du Sandwich. On va faire un token qui protège l'achat ou vente du token dans les DEXes en-chain.

En eigenphi des exemples des Attaques de Sandwich on chain.

https://www.youtube.com/watch?v=KMgAfsGs8es&list=PLRqVznADKueHhGXnFwDfQzb483dmclpT_&index=1&t=7s

Avant de commencer

Pour ce video tu auras besoin de Metamask ou n'importe quel wallet compatible avec l'EVM et aussi du GoerliETH que tu peux trouver gratuitement en un faucet.

Token ERC20 avec mécanisme anti-sandwich

Faites attention a utiliser un router qui existe dans lo blockchain que vous êtes en train d'utiliser.

Uniswap Router: 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D
Quickswap Router: 0xa5E0829CaCEd8fFDD4De3c43696c57F7D7A678ff
Pancakeswap Router: 0x10ED43C718714eb63d5aA57B78B54704E256024E

// SPDX-License-Identifier: MIT
pragma solidity 0.8.16;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

interface IUniswapV2Factory {
    function createPair(address tokenA, address tokenB) external returns (address pair);
}

interface IUniswapV2Router {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);
}

contract MyToken is ERC20 {
    mapping(address => uint256) public lastTxByAddress;
    uint public blockCooldownAmount = 1;
    address pair;

    constructor() ERC20("My Token", "MTKN") {
        _mint(msg.sender, 1_000_000 ether);

        IUniswapV2Router uniswapRouter = IUniswapV2Router(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        pair = IUniswapV2Factory(uniswapRouter.factory()).createPair(address(this), uniswapRouter.WETH());
    }

    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal override {
        amount;
        if(from == pair)
        {
            ensureMaxTxFrequency(to);
            lastTxByAddress[to] = block.number;
        } else if(to == pair)
        {
            ensureMaxTxFrequency(from);
            lastTxByAddress[from] = block.number;
        }else
        {
            ensureMaxTxFrequency(from);
            lastTxByAddress[from] = block.number;
            ensureMaxTxFrequency(to);
            lastTxByAddress[to] = block.number;
        }
    }

    function ensureMaxTxFrequency(address addr) internal virtual {
        bool isAllowed = lastTxByAddress[addr] == 0 ||
            ((lastTxByAddress[addr] + blockCooldownAmount) < (block.number + 1));
        require(isAllowed, "Max tx frequency exceeded!");
    }
}

¡Merci pour voir ce video!

Suivez nous ici en dev.to et en Youtube pour tout ce qui a à voir avec Blockchain en Francais.

Ajoutez le boutton de "Mint NFT" sur votre site web

Ahmed Castro — Tue, 23 Aug 2022 17:23:33 +0000

Les projets de NFTs de collections plus célèbres ont commencé avec une website pour minter. On ce vidéo on va créer un smart contract en Goerli déployer une UI avec un bouton de mint.

Dépendances

Pour ce tutoriel tu vas avoir besoin de NodeJs, je vous conseille de le télécharger avec NVM, aussi on aura besoin d'une RPC URL, je vous conseille d'utiliser INFURA, et puis Metamask avec du GoerliETH que to peux trouver dans un Faucet.

1. Configuration initiale

mkdir MyNFTCollection
cd MyNFTCollection
npm install --save-dev truffle dotenv @truffle/hdwallet-provider @openzeppelin/contracts
npx truffle init

truffle-config.js

require('dotenv').config()
const HDWalletProvider = require('@truffle/hdwallet-provider');

const fs = require('fs');

module.exports = {
  networks: {
    development: {
      host: "127.0.0.1",
      port: 8545,
      network_id: "*",
    },
    goerli: {
      provider: function () {
        return new HDWalletProvider(process.env.PRIVATE_KEY, process.env.GOERLI_RPC_URL);
      },
      network_id: 4,
      gas: 4000000,
      networkCheckTimeout: 10000
    }
  },
  mocha: {
  },
  compilers: {
    solc: {
      version: "0.8.16",
    }
  },
  db: {
    enabled: false
  }
};

2. Déployer le contrat

Créez et éditez le contrat suivant a votre convenance.

contracts/MyNFT.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.16;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/utils/Counters.sol";

contract MyNFT is ERC721Enumerable {
    uint256 public MAX_ELEMENTS = 5;
    uint256 public PRICE = 0.01 ether;
    address public CREATOR = 0x0000000000000000000000000000000000000000;
    uint256 public token_count;
    using Counters for Counters.Counter;
    Counters.Counter private _tokenIdTracker;

    constructor() ERC721("My NFT", "MNFT") {}

    function _baseURI() internal view virtual override returns (string memory) {
        return "MIURL";
    }

    function _totalSupply() internal view returns (uint) {
        return _tokenIdTracker.current();
    }

    function totalMint() public view returns (uint256) {
        return _totalSupply();
    }

    function mint(address _to, uint256 _count) public payable {
        uint256 total = _totalSupply();
        require(total + _count <= MAX_ELEMENTS, "Max limit");
        require(total <= MAX_ELEMENTS, "Sale end");
        require(msg.value >= PRICE*_count, "Value below price");

        for (uint256 i = 0; i < _count; i++) {
            _mintAnElement(_to);
        }
    }

    function _mintAnElement(address _to) private {
        uint id = _totalSupply();
        _tokenIdTracker.increment();
        _safeMint(_to, id);
    }

    function withdrawAll() public {
        (bool success, ) = CREATOR.call{value:address(this).balance}("");
        require(success, "Transfer failed.");
    }
}

migrations/1_my_deploy.js

const MyNFT = artifacts.require("MyNFT")

module.exports = async function (deployer) {
  await deployer.deploy(MyNFT)
}

.env

GOERLI_RPC_URL=YOURRPCKEY
PRIVATE_KEY=YOURPRIVATEKEY

npx truffle migrate --network goerli

3. Le frontend

Créez le dossier client/contracts, créez dedans le fichier MyNFTABI.json et copypastez dedans l'atribut abi dans le fichier build/contracts/MyNFT.json. De plus, modifiez le HTML et le JS a votre convenance.

client/index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
</head>
<body>
  <input id="connect_button" type="button" value="Connect" onclick="connectWallet()" style="display: none"></input>
  <p id="account_address" style="display: none"></p>
  <p id="web3_message"></p>
  <p id="contract_state"></p>
  <select id="mint_amount">
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>
    <option value="4">4</option>
  </select>
  <input type="button" value="mint!" onclick="_mint()">
  <p id="nft_price"></p>
  <p id="nft_balance"></p>
  <br>
  <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/web3/1.3.5/web3.min.js"></script>
  <script type="text/javascript" src="blockchain_stuff.js"></script>
</body>
</html>

<script>
  function _mint()
  {
    mint_amount = document.getElementById("mint_amount").value
    mint(mint_amount)
  }
</script>

Rapelez vous copypaster l'address du contract en MY_NFT_CONTRACT_ADDRESS.

client/blockchain_stuff.js

const NETWORK_ID = 5

const MY_NFT_CONTRACT_ADDRESS = "0xc7c463b90B393b4A0d3650Aa70a08211a6D5fB79"
const MY_NFT_CONTRACT_ABI_PATH = "./MyNFTABI.json"
var my_nft_contract
var price

var accounts
var web3

function metamaskReloadCallback() {
  window.ethereum.on('accountsChanged', (accounts) => {
    document.getElementById("web3_message").textContent="Network changed, refreshing...";
    window.location.reload()
  })
  window.ethereum.on('networkChanged', (accounts) => {
    document.getElementById("web3_message").textContent="Network chainged, refreshing...";
    window.location.reload()
  })
}

const getWeb3 = async () => {
  return new Promise((resolve, reject) => {
    if(document.readyState=="complete")
    {
      if (window.ethereum) {
        const web3 = new Web3(window.ethereum)
        window.location.reload()
        resolve(web3)
      } else {
        reject("must install MetaMask")
        document.getElementById("web3_message").textContent="Error: Connect to Metamask";
      }
    }else
    {
      window.addEventListener("load", async () => {
        if (window.ethereum) {
          const web3 = new Web3(window.ethereum)
          resolve(web3)
        } else {
          reject("must install MetaMask")
          document.getElementById("web3_message").textContent="Error: Please install Metamask";
        }
      });
    }
  });
};

const getContract = async (web3, address, abi_path) => {
  const response = await fetch(abi_path);
  const data = await response.json();

  const netId = await web3.eth.net.getId();
  contract = new web3.eth.Contract(
    data,
    address
    );
  return contract
}

async function loadDapp() {
  metamaskReloadCallback()
  document.getElementById("web3_message").textContent="Please connect to Metamask"
  var awaitWeb3 = async function () {
    web3 = await getWeb3()
    web3.eth.net.getId((err, netId) => {
      if (netId == NETWORK_ID) {
        var awaitContract = async function () {
          my_nft_contract = await getContract(web3, MY_NFT_CONTRACT_ADDRESS, MY_NFT_CONTRACT_ABI_PATH)
          document.getElementById("web3_message").textContent="You are connected to Metamask"
          onContractInitCallback()
          web3.eth.getAccounts(function(err, _accounts){
            accounts = _accounts
            if (err != null)
            {
              console.error("An error occurred: "+err)
            } else if (accounts.length > 0)
            {
              onWalletConnectedCallback()
              document.getElementById("account_address").style.display = "block"
            } else
            {
              document.getElementById("connect_button").style.display = "block"
            }
          });
        };
        awaitContract();
      } else {
        document.getElementById("web3_message").textContent="Please connect to Goerli";
      }
    });
  };
  awaitWeb3();
}

async function connectWallet() {
  await window.ethereum.request({ method: "eth_requestAccounts" })
  accounts = await web3.eth.getAccounts()
  onWalletConnectedCallback()
}

loadDapp()

const onContractInitCallback = async () => {
  price = await my_nft_contract.methods.PRICE().call()
  document.getElementById("nft_price").textContent = "NFT Price: " + web3.utils.fromWei(price) + " ETH";
}

const onWalletConnectedCallback = async () => {
  balance = await my_nft_contract.methods.balanceOf(accounts[0]).call()
  document.getElementById("nft_balance").textContent= "Your balance: " + balance;
}


//// Functions ////

const mint = async (amount) => {
  const result = await my_nft_contract.methods.mint(accounts[0], amount)
  .send({ from: accounts[0], gas: 0, value: price * amount })
  .on('transactionHash', function(hash){
    document.getElementById("web3_message").textContent="Executing...";
  })
  .on('receipt', function(receipt){
    document.getElementById("web3_message").textContent="Success.";    })
  .catch((revertReason) => {
    console.log("ERROR! Transaction reverted: " + revertReason.receipt.transactionHash)
  });
}

4. Essayons le site web

npm install -g lite-server
cd client
lite-server

On peut voir le résultat sur http://localhost:3000.

Maintenant on peut changer le smart contract et adapter l'UI du site web. Je vous conseille d'utiliser Netlify pour déployer, c'est gratuit et simple. De plus, utilisez le répo sur Github si vous avez besoin.

¡Merci pour regarder ce tutoriel!