BridgePoint DEX

Introduction

This is a Decentralized Exchange (DEX) capable of doing the following:

• Users can deposit tokens (like Token A and Token B)
• Users can create buy/sell orders (e.g., "I want to buy 10 Token A for 2 Token B each")
• The system matches compatible orders and executes trades automatically
• Everything is stored on the blockchain (transparent and secure)

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Project Structure

decentralized-exchange/
├── contracts/           # Solidity smart contracts
│   ├── AssetToken.sol   # ERC-20 token contract
│   └── DEX.sol          # Main DEX contract
├── frontend/            # React + Vite frontend
│   ├── src/
│   │   ├── hooks/
│   │   │   └── useDEX.js        # Custom hook for DEX interactions
│   │   ├── utils/
│   │   │   └── contractConfig.js # Contract addresses and ABIs
│   │   └── App.jsx             # Main React component
│   └── package.json
├── scripts/
│   └── deploy.js        # Deployment script
└── hardhat.config.cjs   # Hardhat configuration

Backend (Smart Contracts) - /contracts

1. AssetToken.sol - Your Cryptocurrency Token

• This creates a basic token (like Ethereum's ERC-20 standard)
• You can mint tokens, transfer them, etc.
• Think of it as "coins" people can trade

2. DEX.sol - The Exchange Logic

• This is the brain of your exchange
• Handles deposits, withdrawals, order creation, and order matching
• Stores all orders in an "order book" (like a stock exchange board)

Key Functions:

• deposit() - Put tokens into the exchange
• withdraw() - Take tokens out
• createBuyOrder() - "I want to buy X tokens"
• createSellOrder() - "I want to sell X tokens"
• matchOrders() - Automatically matches buy/sell orders

Frontend in React - /frontend

What it does:

• Beautiful web interface to interact with your smart contracts
• Users can connect their MetaMask wallet
• View balances, create orders, see the order book
• Everything happens through a web browser

Key Files:

• App.jsx - Main UI component
• hooks/useDEX.js - Connects frontend to blockchain
• utils/contractConfig.js - Contract addresses and ABIs (the "interface")

Deployment - /scripts

deploy.js - Deploys your contracts to the blockchain

• Creates Token A and Token B
• Deploys the DEX contract
• Gives you addresses to use in the frontend

Configuration - Root Directory

hardhat.config.cjs - Configures Hardhat (development tool)

• Sets Solidity version
• Configures networks (local testnet, Sepolia testnet, etc.)
• Most important config file!

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How it all works together

User Opens Browser
       ↓
Connects MetaMask Wallet
       ↓
Frontend (React) loads contract addresses
       ↓
User clicks "Deposit" or "Create Order"
       ↓
Frontend calls smart contract function via ethers.js
       ↓
Smart contract executes on blockchain
       ↓
Transaction confirmed → Frontend updates UI

Example Flow:

1. User wants to buy 10 Token A for 2 Token B each
2. User fills form in frontend → clicks "Create Buy Order"
3. Frontend sends transaction to DEX.sol → createBuyOrder()
4. Smart contract checks: Does user have enough Token B? (they need 20 Token B)
5. If yes: Creates order, deducts 20 Token B from user's balance
6. Order appears in order book
7. Another user can create a matching sell order
8. matchOrders() function executes the trade automatically

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How to test (Simple Steps)

Step 1: Make Sure Everything Is Installed

#  in root
npm install

# cd to the frontend folder
cd frontend
npm install
cd ..

Step 2: Start Local Blockchain

Open Terminal 1:

# in root
npx hardhat node

This creates the local Ethereum network

Step 3: Deploy Contracts

Open Terminal 2 (new terminal window):

# in root
npx hardhat run scripts/deploy.js --network localhost

Copy the contract addresses it gives you (Token A, Token B, DEX address)

Step 4: Update Frontend Config

Update frontend/src/utils/contractConfig.js:

• Replace DEX_CONTRACT_ADDRESS with the address from Step 4

Update frontend/src/App.jsx:

• Replace the token addresses in the useEffect with addresses from Step 4

Step 5: Configure MetaMask

1. Open MetaMask browser extension

2. Click network dropdown → "Add Network" → "Add a network manually"

3. Fill in:

   • Network Name: Hardhat Local
   • RPC URL: http://127.0.0.1:8545
   • Chain ID: 31337
   • Currency Symbol: ETH

4. Click "Save"

5. Import a test account:

   • Click your account icon → “Import Account”
   • Import Address 1 or Address 2 from your npx hardhat node output
   • These are the two funded accounts used by the deploy script for Token A and Token B
   • You may import one or both of them into MetaMask to test deposits, orders, and trades

Step 6: Start Frontend

Open Terminal 3:

cd frontend
npm run dev

Step 8: Test

1. Open browser to localhost
2. Click "Connect Wallet" in MetaMask
3. You should see your balances
4. Try depositing some tokens
5. Create a buy or sell order

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