Merge pull request #56 from euler-xyz/alt-protocol-fee

clean protocol fee impl

Author: hoytech

src/EulerSwap.sol

@@ -23,7 +23,9 @@ contract EulerSwap is IEulerSwap, EVCUtil {
     address public immutable eulerAccount;
     uint112 public immutable equilibriumReserve0;
     uint112 public immutable equilibriumReserve1;
-    uint256 public immutable feeMultiplier;
+    uint256 public immutable fee;
+    uint256 public immutable protocolFee;
+    address public immutable protocolFeeRecipient;
 
     uint256 public immutable priceX;
     uint256 public immutable priceY;
@@ -83,7 +85,9 @@ contract EulerSwap is IEulerSwap, EVCUtil {
         equilibriumReserve1 = params.equilibriumReserve1;
         reserve0 = params.currReserve0;
         reserve1 = params.currReserve1;
-        feeMultiplier = 1e18 - params.fee;
+        fee = params.fee;
+        protocolFee = 0.1e18;
+        protocolFeeRecipient = address(0);
 
         // Curve params
 
@@ -120,11 +124,8 @@ contract EulerSwap is IEulerSwap, EVCUtil {
 
         // Deposit all available funds, adjust received amounts downward to collect fees
 
-        uint256 amount0In = IERC20(asset0).balanceOf(address(this));
-        if (amount0In > 0) amount0In = depositAssets(vault0, amount0In) * feeMultiplier / 1e18;
-
-        uint256 amount1In = IERC20(asset1).balanceOf(address(this));
-        if (amount1In > 0) amount1In = depositAssets(vault1, amount1In) * feeMultiplier / 1e18;
+        uint256 amount0In = depositAssets(asset0, vault0);
+        uint256 amount1In = depositAssets(asset1, vault1);
 
         // Verify curve invariant is satisfied
 
@@ -211,14 +212,29 @@ contract EulerSwap is IEulerSwap, EVCUtil {
     }
 
     /// @notice Deposits assets into a vault and automatically repays any outstanding debt
+    /// @param asset The address of the underlying asset
     /// @param vault The address of the vault to deposit into
-    /// @param amount The amount of assets to deposit
     /// @return The amount of assets successfully deposited
     /// @dev This function attempts to deposit assets into the specified vault.
     /// @dev If the deposit fails with E_ZeroShares error, it safely returns 0 (this happens with very small amounts).
     /// @dev After successful deposit, if the user has any outstanding controller-enabled debt, it attempts to repay it.
     /// @dev If all debt is repaid, the controller is automatically disabled to reduce gas costs in future operations.
-    function depositAssets(address vault, uint256 amount) internal returns (uint256) {
+    function depositAssets(address asset, address vault) internal returns (uint256) {
+        uint256 amount = IERC20(asset).balanceOf(address(this));
+        if (amount == 0) return 0;
+
+        uint256 feeAmount = amount * fee / 1e18;
+
+        {
+            uint256 protocolFeeAmount = feeAmount * protocolFee / 1e18;
+
+            if (protocolFeeAmount != 0) {
+                IERC20(asset).transfer(protocolFeeRecipient, protocolFeeAmount);
+                amount -= protocolFeeAmount;
+                feeAmount -= protocolFeeAmount;
+            }
+        }
+
         uint256 deposited;
 
         if (IEVC(evc).isControllerEnabled(eulerAccount, vault)) {
@@ -238,13 +254,13 @@ contract EulerSwap is IEulerSwap, EVCUtil {
             try IEVault(vault).deposit(amount, eulerAccount) {}
             catch (bytes memory reason) {
                 require(bytes4(reason) == EVKErrors.E_ZeroShares.selector, DepositFailure(reason));
-                return deposited;
+                amount = 0;
             }
 
             deposited += amount;
         }
 
-        return deposited;
+        return deposited > feeAmount ? deposited - feeAmount : 0;
     }
 
     /// @notice Approves tokens for a given vault, supporting both standard approvals and permit2

src/EulerSwapFactory.sol

@@ -23,7 +23,7 @@ contract EulerSwapFactory is IEulerSwapFactory, EVCUtil {
         address indexed asset1,
         address vault0,
         address vault1,
-        uint256 indexed feeMultiplier,
+        uint256 indexed fee,
         address eulerAccount,
         uint256 reserve0,
         uint256 reserve1,
@@ -70,7 +70,7 @@ contract EulerSwapFactory is IEulerSwapFactory, EVCUtil {
             pool.asset1(),
             params.vault0,
             params.vault1,
-            pool.feeMultiplier(),
+            pool.fee(),
             params.eulerAccount,
             params.currReserve0,
             params.currReserve1,

src/EulerSwapPeriphery.sol

@@ -105,11 +105,11 @@ contract EulerSwapPeriphery is IEulerSwapPeriphery {
         );
         require(amount <= type(uint112).max, SwapLimitExceeded());
 
-        uint256 feeMultiplier = eulerSwap.feeMultiplier();
+        uint256 fee = eulerSwap.fee();
         (uint112 reserve0, uint112 reserve1,) = eulerSwap.getReserves();
 
-        // exactIn: decrease received amountIn, rounding down
-        if (exactIn) amount = amount * feeMultiplier / 1e18;
+        // exactIn: decrease effective amountIn
+        if (exactIn) amount = amount - (amount * fee / 1e18);
 
         bool asset0IsInput = checkTokens(eulerSwap, tokenIn, tokenOut);
         (uint256 inLimit, uint256 outLimit) = calcLimits(eulerSwap, asset0IsInput);
@@ -124,8 +124,8 @@ contract EulerSwapPeriphery is IEulerSwapPeriphery {
             require(amount <= outLimit && quote <= inLimit, SwapLimitExceeded());
         }
 
-        // exactOut: increase required quote(amountIn), rounding up
-        if (!exactIn) quote = (quote * 1e18 + (feeMultiplier - 1)) / feeMultiplier;
+        // exactOut: inflate required amountIn
+        if (!exactIn) quote = (quote * 1e18) / (1e18 - fee);
 
         return quote;
     }

src/interfaces/IEulerSwap.sol

@@ -50,7 +50,9 @@ interface IEulerSwap {
     function eulerAccount() external view returns (address);
     function equilibriumReserve0() external view returns (uint112);
     function equilibriumReserve1() external view returns (uint112);
-    function feeMultiplier() external view returns (uint256);
+    function fee() external view returns (uint256);
+    function protocolFee() external view returns (uint256);
+    function protocolFeeRecipient() external view returns (address);
     /// @notice Returns the current reserves of the pool
     /// @return reserve0 The amount of asset0 in the pool
     /// @return reserve1 The amount of asset1 in the pool

test/Fees.t.sol

@@ -58,8 +58,10 @@ contract FeesTest is EulerSwapTestBase {
 
         // Holder's NAV increased by fee amount, plus slightly extra because we are not at curve equilibrium point
 
-        assertGt(getHolderNAV(), origNav + int256(amountIn - amountInNoFees));
-        assertEq(eTST.balanceOf(address(holder)), 10e18 + amountIn);
+        uint256 protocolFeesCollected = assetTST.balanceOf(address(0));
+
+        assertGt(getHolderNAV() + int256(protocolFeesCollected), origNav + int256(amountIn - amountInNoFees));
+        assertEq(eTST.balanceOf(address(holder)), 10e18 + amountIn - protocolFeesCollected);
         assertEq(eTST2.balanceOf(address(holder)), 10e18 - amountOut);
     }
 
@@ -107,8 +109,10 @@ contract FeesTest is EulerSwapTestBase {
 
         // Holder's NAV increased by fee amount, plus slightly extra because we are not at curve equilibrium point
 
-        assertGt(getHolderNAV(), origNav + int256(amountIn - amountInNoFees));
-        assertEq(eTST.balanceOf(address(holder)), 10e18 + amountIn);
+        uint256 protocolFeesCollected = assetTST.balanceOf(address(0));
+
+        assertGt(getHolderNAV() + int256(protocolFeesCollected), origNav + int256(amountIn - amountInNoFees));
+        assertEq(eTST.balanceOf(address(holder)), 10e18 + amountIn - protocolFeesCollected);
         assertEq(eTST2.balanceOf(address(holder)), 10e18 - amountOut);
     }
 }