Monster

- Blockchain-based Banking and NFT Shop System

This project is a comprehensive blockchain-based system that combines a banking contract with an NFT shop contract, built on the Arc testnet. It features a full-stack implementation with smart contracts, backend API server, and frontend interface.

try it out here (make sure your metamask or compatible wallet extension installed)

Project Overview

The Monster project is a decentralized application (dApp) that combines:

• A Bank contract for managing USDC deposits and withdrawals
• An NFT Shop contract for minting and managing ERC721 NFTs
• A backend API server that connects to the blockchain
• A frontend interface for user interaction

This system demonstrates how blockchain technology can be used for both financial services and digital asset management in a unified platform.

Project Structure

monster/
├── backend/
│   ├── contracts/
│   │   ├── Bank.sol         # Bank smart contract
│   │   └── Shop.sol         # NFT shop smart contract
│   ├── scripts/
│   │   └── deploy.js        # Deployment script
│   ├── server.js            # Backend API server
│   ├── hardhat.config.js    # Hardhat configuration
│   ├── package.json         # Backend dependencies
│   └── README.md            # Backend documentation
│
├── frontend/
│   ├── index.html           # Main HTML file
│   ├── package.json         # Frontend dependencies
│   ├── src/
│   │   ├── App.tsx          # Main React component
│   │   ├── main.tsx         # Entry point
│   │   └── index.css        # Styles
│   ├── vite.config.ts       # Vite configuration
│   ├── tailwind.config.js   # Tailwind CSS configuration
│   └── postcss.config.js    # PostCSS configuration
│
├── bank.sol                 # Bank contract source
├── shop.sol                 # Shop contract source
├── package.json             # Root dependencies
├── README.md                # This file
└── demo.gif                 # Project demonstration

System Workflow

┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│   Frontend      │    │   Backend API   │    │   Blockchain    │
│   (React)       │    │   (Node.js)     │    │   (Arc Testnet) │
└─────────────────┘    └─────────────────┘    └─────────────────┘
        │                       │                       │
        │ 1. User actions       │                       │
        │ ────────────────────▶│                       │
        │                       │                       │
        │                       │ 2. Contract calls     │
        │                       │ ────────────────────▶│
        │                       │                       │
        │                       │ 3. Transaction       │
        │                       │    broadcast          │
        │                       │ ────────────────────▶│
        │                       │                       │
        │                       │ 4. Transaction        │
        │                       │    confirmation       │
        │                       │ ◀─────────────────── │
        │                       │                       │
        │ 5. Response           │                       │
        │ ◀─────────────────── │                       │
        │                       │                       │
        │ 6. UI update          │                       │
        │ ◀─────────────────── │                       │
        │                       │                       │

Smart Contracts

1. Bank Contract (bank.sol)

A simple bank contract that allows users to deposit and withdraw USDC (under Arc testnet).

Key Features:

• deposit() - Accepts USDC deposits from users
• withdraw(address to, uint amount) - Withdraws USDC to a specified address
• balances - Mapping to track user balances
• Secure transaction handling with proper error management

2. Shop Contract (shop.sol)

An ERC721 NFT shop contract that allows users to mint and manage NFTs.

Key Features:

• mint(string memory _name, string memory _image) - Mint new NFTs
• modifyPig(uint _id, string memory _name, string memory _image) - Modify existing NFTs
• tokenURI(uint _id) - Returns metadata for NFTs
• getPig(uint _id) - Retrieve NFT information
• getBalance() - Check contract balance
• Owner-only functions for shop management:
  • changeOwner(address newOwner)
  • setPigFee(uint _cost)
  • redeem(address _to, uint _amount)
  • closeShop(bool _close)

Dependencies:

• Uses OpenZeppelin's ERC721 implementation
• Uses OpenZeppelin's Base64 library for metadata encoding

Backend API Server

The backend server provides RESTful API endpoints to interact with the smart contracts:

API Endpoints

Bank Endpoints:

• POST /bank/deposit - Deposit funds into the bank contract
• POST /bank/withdraw - Withdraw funds from the bank contract
• GET /bank/balance/:address - Get user balance

Shop Endpoints:

• POST /shop/mint - Mint new NFTs
• GET /shop/get-pig/:id - Get NFT information
• GET /shop/balance - Get shop contract balance

Server Features:

• Express.js based API server
• Contract interaction using Hardhat
• JSON response handling
• Error management
• Environment configuration support

Frontend Interface

The frontend is a React-based interface that allows users to interact with the system:

• User-friendly interface for banking operations
• NFT minting and viewing capabilities
• Real-time balance updates
• Responsive design using Tailwind CSS

Deployment

Prerequisites

1. Install Node.js and npm
2. Create a .env file in the backend directory with your private key:

   PRIVATE_KEY=your_private_key_here
   

Local Deployment

To deploy contracts to the local Hardhat network:

cd backend
npx hardhat run scripts/deploy.js --network hardhat

Testnet Deployment (Arc)

To deploy to the Arc testnet:

cd backend
npx hardhat run scripts/deploy.js --network arc

Running the Application

1. Start the backend server:

   cd backend
   node server.js

2. Start the frontend development server:

   cd frontend
   npm run dev

Contract Deployment Addresses

• Bank contract: 0xEDeBb64Fa2D6DA4DD005B69f10Ec218b45E64fc9
• Shop contract: 0xB95BE2Acdf69E9A5357606f7031933c598259772

License

This project is under MIT License

Contributing Guidelines

• Welcome to all contributors
• For agentic-commerce-on-arc submission recently
• Please follow the code style and testing guidelines
• Submit pull requests for review

Future Improvements

• Add more comprehensive frontend features
• Implement user authentication
• Add advanced contract management
• Include more detailed analytics
• Expand NFT functionality