# Smart Contracts (Optional)

QuickDapp includes sample smart contracts for Web3 developers. If you're building a non-Web3 application, skip this section entirely.

# Overview

The sample contracts demonstrate a simple ERC20 token factory pattern using OpenZeppelin contracts and Foundry tooling. The factory deploys new ERC20 tokens with custom names, symbols, and initial supplies.

Both contracts live in sample-contracts/src/ERC20Factory.sol:

ERC20Factory - Deploys new ERC20 tokens and tracks them
SimpleERC20 - Basic ERC20 with mint/burn capabilities and custom transfer events

# Directory Structure

sample-contracts/
├── src/
│   └── ERC20Factory.sol      # Factory and token contracts
├── devnet.ts                 # Local Hardhat blockchain
├── deploy.ts                 # Foundry deployment script
├── foundry.toml              # Foundry configuration
└── hardhat.config.cjs        # Hardhat node configuration

# Local Development

Start the local blockchain and deploy contracts in separate terminals:

# Terminal 1: Start local blockchain
cd sample-contracts
bun devnet.ts

# Terminal 2: Deploy contracts
cd sample-contracts
bun deploy.ts

The deployment script uses Foundry's forge create to deploy ERC20Factory, then automatically updates .env.local with the deployed contract address.

# Factory Interface

The factory tracks deployed tokens and emits events for indexing:

contract ERC20Factory {
    event ERC20NewToken(
        address indexed token,
        string name,
        string symbol,
        address indexed creator,
        uint256 initialSupply
    );

    function erc20DeployToken(
        ERC20TokenConfig memory config,
        uint256 initialBalance
    ) external returns (address);

    function getNumErc20s() external view returns (uint256);
    function getErc20Address(uint256 index) external view returns (address);
    function getAllErc20Addresses() external view returns (address[] memory);
}

Token configuration uses a struct:

struct ERC20TokenConfig {
    string name;
    string symbol;
    uint8 decimals;
}

# Testnet Deployment

Deploy to Sepolia or other testnets by configuring environment variables:

# In your .env.local
WEB3_SUPPORTED_CHAINS=sepolia
WEB3_SEPOLIA_RPC=https://sepolia.infura.io/v3/YOUR_KEY
WEB3_SERVER_WALLET_PRIVATE_KEY=0x...

# Deploy
cd sample-contracts
bun deploy.ts

The script reads from the first chain in WEB3_SUPPORTED_CHAINS and uses the corresponding RPC endpoint.

# Testing

Run Foundry tests for contract verification:

cd sample-contracts
forge test           # Run all tests
forge test -vvv      # Verbose output
forge test --gas-report

# Frontend Integration

After deployment, the contract address is available via clientConfig.WEB3_FACTORY_CONTRACT_ADDRESS. ABIs are generated from Foundry build artifacts to src/shared/abi/generated.ts when you run bun run gen.

Use viem/wagmi on the client for contract interactions. The ERC20NewToken and TokenTransferred events are useful for real-time tracking via WebSockets.

# Customization

To add your own contracts:

Add Solidity files to sample-contracts/src/
Run forge build to compile
Update deploy.ts to deploy your contracts
Run bun run gen to regenerate ABI types