feat: integrate xSGD token into exchange contract and update related tests

Author: dannweeeee

README.md

@@ -6,9 +6,10 @@
 ## Contracts
 
 1. Registry.sol: [0x2b4836d81370e37030727e4dcbd9cc5a772cf43a](https://sepolia.basescan.org/address/0x2b4836d81370e37030727e4dcbd9cc5a772cf43a)
-2. Exchange.sol: [0xd9004Edc4bdEB308C4A40fdCbE320bbE5DF4AF77](https://sepolia.basescan.org/address/0xd9004edc4bdeb308c4a40fdcbe320bbe5df4af77)
-3. Vault.sol: [0xd580248163CDD5AE3225A700E9f4e7CD525b27b0](https://sepolia.basescan.org/address/0xd580248163cdd5ae3225a700e9f4e7cd525b27b0)
-4. XSGD.sol [0xd7260d7063fE5A62A90E6A8DD5A39Ab27A05986B](https://sepolia.basescan.org/token/0xd7260d7063fe5a62a90e6a8dd5a39ab27a05986b)
+2. Exchange.sol (V1): [0xd9004Edc4bdEB308C4A40fdCbE320bbE5DF4AF77](https://sepolia.basescan.org/address/0xd9004edc4bdeb308c4a40fdcbe320bbe5df4af77)
+3. Exchange.sol (V2): [0x92F5D70ffBE0988DEcD5c1E7A6cb8A048a3Fe75D](https://sepolia.basescan.org/address/0x92F5D70ffBE0988DEcD5c1E7A6cb8A048a3Fe75D)
+4. Vault.sol: [0xd580248163CDD5AE3225A700E9f4e7CD525b27b0](https://sepolia.basescan.org/address/0xd580248163cdd5ae3225a700e9f4e7cd525b27b0)
+5. XSGD.sol: [0xd7260d7063fE5A62A90E6A8DD5A39Ab27A05986B](https://sepolia.basescan.org/token/0xd7260d7063fe5a62a90e6a8dd5a39ab27a05986b)
 
 ## Deployment
 

script/deploy/Exchange.s.sol

@@ -11,9 +11,10 @@ contract DeployExchange is Script {
 
         address registryAddress = 0x2b4836d81370e37030727E4DCbd9cC5a772cf43A;
         address usdcAddress = 0x036CbD53842c5426634e7929541eC2318f3dCF7e;
+        address xsgdAddress = 0xd7260d7063fE5A62A90E6A8DD5A39Ab27A05986B;
         address vaultAddress = 0xd580248163CDD5AE3225A700E9f4e7CD525b27b0;
 
-        Exchange exchange = new Exchange(registryAddress, usdcAddress, vaultAddress);
+        Exchange exchange = new Exchange(registryAddress, usdcAddress, xsgdAddress, vaultAddress);
 
         console.log("Exchange deployed at:", address(exchange));
 

src/Exchange.sol

@@ -19,6 +19,7 @@ contract Exchange is ReentrancyGuard, Ownable {
 
     Registry public immutable registry;
     IERC20 public immutable usdcToken;
+    IERC20 public immutable xsgdToken;
     IERC4626 public immutable vault;
 
     uint256 public fee = 100; // 100 basis points fee (1%)
@@ -34,12 +35,16 @@ contract Exchange is ReentrancyGuard, Ownable {
     event VaultDeposit(address indexed merchant, uint256 assets, uint256 shares);
     event VaultWithdraw(address indexed merchant, uint256 assets, uint256 shares);
 
-    constructor(address _registryAddress, address _usdcAddress, address _vaultAddress) Ownable(msg.sender) {
+    constructor(address _registryAddress, address _usdcAddress, address _xsgdAddress, address _vaultAddress)
+        Ownable(msg.sender)
+    {
         require(_registryAddress != address(0), "Invalid registry address");
         require(_usdcAddress != address(0), "Invalid USDC address");
+        require(_xsgdAddress != address(0), "Invalid xSGD address");
         require(_vaultAddress != address(0), "Invalid vault address");
         registry = Registry(_registryAddress);
         usdcToken = IERC20(_usdcAddress);
+        xsgdToken = IERC20(_xsgdAddress);
         feeCollector = address(this);
         vault = IERC4626(_vaultAddress);
         lastUpdateTime = block.timestamp;
@@ -55,7 +60,7 @@ contract Exchange is ReentrancyGuard, Ownable {
      * @param _uen Merchant's UEN.
      * @param _amount Amount of USDC to transfer to merchant.
      */
-    function transferToMerchant(string memory _uen, uint256 _amount) external nonReentrant {
+    function transferUsdcToMerchant(string memory _uen, uint256 _amount) external nonReentrant {
         require(_amount > 0, "Amount must be greater than zero");
 
         address merchantWalletAddress = registry.getMerchantByUEN(_uen).wallet_address;
@@ -72,6 +77,23 @@ contract Exchange is ReentrancyGuard, Ownable {
         emit Transfer(msg.sender, merchantWalletAddress, merchantAmount, _uen);
     }
 
+    function transferXsgdToMerchant(string memory _uen, uint256 _amount) external nonReentrant {
+        require(_amount > 0, "Amount must be greater than zero");
+
+        address merchantWalletAddress = registry.getMerchantByUEN(_uen).wallet_address;
+        require(merchantWalletAddress != address(0), "Invalid merchant wallet address");
+
+        uint256 feeAmount = (_amount * fee) / 10000;
+        uint256 merchantAmount = _amount - feeAmount;
+
+        xsgdToken.safeTransferFrom(msg.sender, merchantWalletAddress, merchantAmount);
+        if (feeAmount > 0) {
+            xsgdToken.safeTransferFrom(msg.sender, feeCollector, feeAmount);
+        }
+
+        emit Transfer(msg.sender, merchantWalletAddress, merchantAmount, _uen);
+    }
+
     /**
      * @notice Transfer USDC to vault.
      * @param _uen Merchant's UEN.
@@ -154,11 +176,11 @@ contract Exchange is ReentrancyGuard, Ownable {
     }
 
     /**
-     * @notice Withdraw fees.
+     * @notice Withdraw USDC fees.
      * @param _to Withdrawal address.
      * @param _amount Amount of USDC to withdraw.
      */
-    function withdrawFees(address _to, uint256 _amount) external onlyOwner {
+    function withdrawUsdcFees(address _to, uint256 _amount) external onlyOwner {
         require(_to != address(0), "Invalid withdrawal address");
         require(_amount > 0, "Withdrawal amount must be greater than zero");
         require(_amount <= usdcToken.balanceOf(address(this)), "Insufficient balance");
@@ -167,6 +189,24 @@ contract Exchange is ReentrancyGuard, Ownable {
         emit FeesWithdrawn(_to, _amount);
     }
 
+    /**
+     * @notice Withdraw XSGD fees.
+     * @param _to Withdrawal address.
+     * @param _amount Amount of XSGD to withdraw.
+     */
+    function withdrawXsgdFees(address _to, uint256 _amount) external onlyOwner {
+        require(_to != address(0), "Invalid withdrawal address");
+        require(_amount > 0, "Withdrawal amount must be greater than zero");
+        require(_amount <= xsgdToken.balanceOf(address(this)), "Insufficient balance");
+
+        xsgdToken.safeTransfer(_to, _amount);
+        emit FeesWithdrawn(_to, _amount);
+    }
+
+    ///////////////////
+    // VAULT HELPERS //
+    ///////////////////
+
     /**
      * @notice Get current price per share
      * @return Current price of 1 share in terms of assets (USDC)