HemDealer: Cross-Chain Car Marketplace

HemDealer is a decentralized application (DApp) designed for buying, selling, and managing cars in a cross-chain environment. Built using Solidity, it leverages the Ethereum blockchain, ERC721 standards, and the Across Protocol to facilitate seamless transactions across different blockchain networks.

Table of Contents

• Features
• Architecture
• Smart Contracts
• Setup & Installation
• Deployment
• Usage
• Testing
• Contributing

Features

Core Features

• NFT Car Listings: Tokenize vehicles as ERC721 NFTs with comprehensive metadata
• Cross-Chain Transfers: Seamless vehicle transfers between different blockchain networks using Across Protocol
• Native Token Payments: Support for ETH and network native tokens
• Secure Ownership: ERC721-based ownership management with cross-chain verification
• Advanced Search: Filter cars by make, model, year, and other attributes
• Event Tracking: Comprehensive event logging for all marketplace activities

Car Management

• Detailed Car Profiles: Comprehensive vehicle information including:
  • Basic details (make, model, year, VIN)
  • Technical specifications
  • Multiple image support
  • Condition assessment
  • Price history
• Listing Management: Create, update, and delete car listings
• Ownership History: Track all previous owners and sales

Security Features

• ReentrancyGuard Protection: Prevent reentrancy attacks
• Cross-Chain Verification: Secure message verification via Across Protocol
• Slippage Protection: Maximum 0.5% slippage tolerance
• Transfer Timeout: 24-hour safety window for cross-chain transfers
• Access Controls: Role-based permissions system
• Payment Validation: Automatic payment verification and processing

Seller Features

• Seller Profiles: Detailed seller information and history
• Multiple Listings: Manage multiple car listings
• Sales Analytics: Track listing performance and sales history
• Cross-Chain Management: List cars on multiple chains

Buyer Features

• Secure Payments: Protected native token transactions
• Cross-Chain Shopping: Browse and buy cars across different networks
• Purchase History: Track all vehicle purchases
• Transfer Tracking: Real-time cross-chain transfer status

Technical Features

• Gas Optimization: Efficient contract design for lower transaction costs
• Event Logging: Comprehensive event emission for frontend tracking
• Upgradeable Design: Modular contract architecture
• Bridge Integration: Seamless Across Protocol integration
• Batch Operations: Support for multiple car operations
• Emergency Controls: Admin functions for emergency situations

Architecture

Core Components

1. Smart Contracts

   • HemDealer.sol: Main marketplace contract (ERC721)
   • HemDealerCrossChain.sol: Cross-chain transfer handler
   • Across Protocol integration for secure cross-chain messaging

2. Frontend Integration

   • Web3 provider integration (ethers.js)
   • MetaMask and Rainbow Wallet support
   • Real-time transaction tracking
   • Responsive UI for car listings

Smart Contracts

HemDealer.sol

Primary marketplace contract handling:

• Car listings and sales
• Ownership management (ERC721)
• Payment processing
• Cross-chain coordination

HemDealerCrossChain.sol

Manages cross-chain operations:

• Transfer initiation and completion
• Message verification via Across Protocol
• Payment bridging
• Timeout handling (24-hour safety)

Setup & Installation

1. Clone the repository:

git clone https://github.com/MujeebSulayman/Car-dealership-dapp.git
cd Car-dealership-dapp

2. Install dependencies:

npm install

3. Configure environment variables:

cp .env.example .env

4. Update .env with your configuration:

# RPC and API Keys
NEXT_PUBLIC_RPC_URL=your_sepolia_rpc_url
NEXT_PUBLIC_ALCHEMY_ID=your_alchemy_id
PRIVATE_KEY=your_private_key

# Across Protocol Addresses (Sepolia)
ACROSS_ROUTER_ADDRESS=0xC499a572640B64eA1C8c194c43Bc3E19940719dC
ACROSS_SPOKE_POOL_ADDRESS=0x7376B2F28E58a7E7103d4185daC1e2c0E272C8A9

Deployment

1. Deploy to Sepolia testnet:

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

2. Verify contracts:

npx hardhat verify --network sepolia <CONTRACT_ADDRESS> "HemDealer" "HEMD"

Usage

Listing a Car

const listCar = async (car: CarParams) => {
  const contract = await getEthereumContract()
  await contract.listCar(
    car.basicDetails,
    car.technicalDetails,
    car.additionalInfo,
    car.sellerDetails,
    car.destinationChainId,
    car.paymentToken
  )
}

Cross-Chain Transfer

const transfer = async (carId: number, destinationChain: number) => {
  // Get quote from Across Protocol
  const quote = await getAcrossQuote(amount, destinationChain)
  
  const contract = await getCrossChainContract()
  await contract.initiateCrossChainTransfer(
    carId,
    destinationChain,
    quote.relayerFeePct,
    quote.quoteTimestamp
  )
}

Testing

Run the test suite:

npx hardhat test

Generate coverage report:

npx hardhat coverage

Contributing

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Socials

• X (Twitter)
• GitHub

Security Features

• ReentrancyGuard implementation
• Ownership validation
• Cross-chain message verification
• Slippage protection (0.5% max)
• Transfer timeout (24 hours)
• Comprehensive access controls

License

MIT License - see LICENSE.md for details