# Lottery DApp

A decentralized Lottery DApp built using Ethereum smart contracts and a web-based frontend. Users can participate in the lottery by sending Ether and have a chance to win the entire balance when the manager picks a winner.

Features

• Allows users to enter the lottery by sending a specified amount of Ether.
• The manager can pick a winner randomly from the list of participants.
• The DApp displays the number of players and the list of participants.

Technologies Used

• Solidity: For writing the smart contract.
• Ethers.js: For interacting with the Ethereum blockchain.
• MetaMask: For connecting to the user's Ethereum wallet.
• HTML/CSS/JavaScript: For the frontend interface.
• Hardhat: For Ethereum development and testing.

Prerequisites

• MetaMask browser extension installed.
• Node.js and npm installed.
• An Ethereum development environment like Hardhat.

Initial Setup

1. Clone the Repository

   git clone https://github.com/your-username/lottery-dapp.git
   cd lottery-dapp

2. Install Dependencies Make sure you are in the project directory and install the necessary npm packages.

   npm install

3. Set Up Hardhat If you haven't already set up a Hardhat environment, create a basic Hardhat configuration.

   npx hardhat

   Follow the prompts to create a new Hardhat project.

4. Create and Configure the Smart Contract

   • Create a new file contracts/Lottery.sol with the following content:

   // SPDX-License-Identifier: MIT
   pragma solidity ^0.8.0;
   
   contract Lottery {
       address public manager;
       address payable[] public players;
   
       constructor() {
           manager = msg.sender;
       }
   
       function participate() public payable {
           require(msg.value >= 0.01 ether, "Minimum 0.01 ether required to participate");
           players.push(payable(msg.sender));
       }
   
       function getNumberOfPlayers() public view returns (uint256) {
           return players.length;
       }
   
       function pickWinner() public restricted {
           require(players.length > 0, "No players have participated");
           uint256 winnerIndex = random() % players.length;
           address payable winner = players[winnerIndex];
           winner.transfer(address(this).balance);
           players = new address payable ; // Reset players after winner is picked
       }
   
       function getPlayers() public view returns (address payable[] memory) {
           return players;
       }
   
       function getBalance() public view returns (uint256) {
           return address(this).balance;
       }
   
       modifier restricted() {
           require(msg.sender == manager, "Only the manager can call this function");
           _;
       }
   
       function random() private view returns (uint256) {
           return uint256(keccak256(abi.encodePacked(block.difficulty, block.timestamp, players.length)));
       }
   }

5. Compile the Contract

   npx hardhat compile

6. Deploy the Contract Create a new deployment script scripts/deploy.js:

   async function main() {
       const Lottery = await ethers.getContractFactory("Lottery");
       const lottery = await Lottery.deploy();
       await lottery.deployed();
       console.log("Lottery contract deployed to:", lottery.address);
   }
   
   main()
       .then(() => process.exit(0))
       .catch((error) => {
           console.error(error);
           process.exit(1);
       });

   Then run the deployment script:

   npx hardhat run scripts/deploy.js --network localhost

   Note: Make sure you have a local Ethereum network running using:

   npx hardhat node

Frontend Setup

1. Update the Contract Address

   • In index.html, update the contractAddress variable with the deployed contract address from the deployment step.

2. Install MetaMask

   • Install MetaMask and connect it to the local Ethereum network (usually http://localhost:8545).

3. Run the Frontend

   • Open index.html in your web browser.

Interacting with the DApp

1. Enter the Lottery

   • Click the "Enter Lottery" button. Make sure you have at least 0.01 Ether in your MetaMask account.

2. Get Players

   • Click the "Get Players" button to view the list of participants.

3. Pick Winner

   • Add a button for the "Pick Winner" functionality (available only to the manager). Update the frontend JavaScript to include the function to pick a winner.

Troubleshooting

• MetaMask Connection Issues: Ensure MetaMask is configured to connect to the correct network.
• Revert Errors: Make sure all contract conditions are met (e.g., minimum Ether for participation, caller is the manager).

Commands Summary

• Clone the repository:

  git clone https://github.com/your-username/lottery-dapp.git

• Install dependencies:

  npm install

• Compile the contract:

  npx hardhat compile

• Start a local Ethereum network:

  npx hardhat node

• Deploy the contract:

  npx hardhat run scripts/deploy.js --network localhost

License

MIT License

This updated `README.md` covers the complete process of setting up and running the Lottery DApp from scratch. It includes commands for each step, providing new users with a clear guide to start the project. Make sure to replace `"your-username"` in the GitHub link with your actual GitHub username if applicable.