Fees

README.MD

@@ -10,7 +10,7 @@ All Smart Pools are fully upgradeable to make it easy to add features and optimi
 
 Clone this repo. And copy the contents of ``env.example`` to a new file called ``.env`` and edit the the relevant values inside. **DO NOT** share this file with anyone as it will contain sensitive data.
 
-Install all dependencies: 
+Install all dependencies:
 ```
 yarn
 ```
@@ -65,6 +65,12 @@ To get the underlying tokens and amounts needed to mint a certain amount of pool
 function calcTokensForAmount(uint256 _amount) external view returns(address[] memory tokens, uint256[] memory amounts);
 ```
 
+To get the underlying tokens and amounts redeemed when exiting a certain amount of pool shares call:
+
+```solidity
+function calcTokensForAmountExit(uint256 _amount) external view returns(address[] memory tokens, uint256[] memory amounts);
+```
+
 #### Balancer smart pool specific
 Get the address of the underlying balancer pool:
 

contracts/interfaces/IPV2SmartPool.sol

@@ -20,7 +20,7 @@ interface IPV2SmartPool is IERC20 {
   ) external;
 
   /**
-    @notice Set the address that can set public swap enabled or disabled. 
+    @notice Set the address that can set public swap enabled or disabled.
     Can only be called by the controller
     @param _swapSetter Address of the new swapSetter
   */
@@ -68,6 +68,16 @@ interface IPV2SmartPool is IERC20 {
   */
   function setFeeRecipient(address _newRecipient) external;
 
+  /**
+    @notice Set the exit fee percentage users have to pay.
+  */
+  function setExitFee(uint256 _fee) external;
+
+  /**
+    @notice Sets the recipient fee percentage share. Can only be set by the current controller
+  */
+  function setExitFeeRecipientShare(uint256 _share) external;
+
   /**
     @notice Set the controller address. Can only be called by the current address
     @param _controller Address of the new controller
@@ -98,7 +108,7 @@ interface IPV2SmartPool is IERC20 {
   */
   function updateWeight(address _token, uint256 _newWeight) external;
 
-  /** 
+  /**
     @notice Gradually adjust the weights of a token. Can only be called by the controller
     @param _newWeights Target weights
     @param _startBlock Block to start weight adjustment
@@ -120,7 +130,7 @@ interface IPV2SmartPool is IERC20 {
   */
   function applyAddToken() external;
 
-  /** 
+  /**
     @notice Commit a token to be added. Can only be called by the controller
     @param _token Address of the token to add
     @param _balance Amount of token to add
@@ -143,7 +153,7 @@ interface IPV2SmartPool is IERC20 {
   */
   function approveTokens() external;
 
-  /** 
+  /**
     @notice Mint pool tokens, locking underlying assets
     @param _amount Amount of pool tokens
   */
@@ -284,7 +294,7 @@ interface IPV2SmartPool is IERC20 {
   */
   function isPublicSwap() external view returns (bool);
 
-  /** 
+  /**
     @notice Get the current tokens in the smart pool
     @return Addresses of the tokens in the smart pool
   */
@@ -308,6 +318,18 @@ interface IPV2SmartPool is IERC20 {
   */
   function getFeeRecipient() external view returns (address);
 
+  /**
+    @notice Get the percetage the recipient gets of the total exit fee.
+    @return Fee recipient share percentage
+  */
+  function getExitFeeRecipientShare() external view returns (uint256);
+
+  /**
+    @notice Get the exit fee percentage
+    @return Exit fee percentage
+  */
+  function getExitFee() external view returns (uint256);
+
   /**
     @notice Get the denormalized weight of a token
     @param _token Address of the token
@@ -389,6 +411,16 @@ interface IPV2SmartPool is IERC20 {
     view
     returns (address[] memory tokens, uint256[] memory amounts);
 
+  /**
+    @notice Calculate the amount of underlying redeemed when exiting with a certain amount
+    @return tokens Addresses of the underlying tokens
+    @return amounts Amounts of the underlying tokens
+  */
+  function calcTokensForAmountExit(uint256 _amount)
+    external
+    view
+    returns (address[] memory tokens, uint256[] memory amounts);
+
   /**
     @notice Calculate the amount of pool tokens out given underlying in
     @param _token Underlying asset to deposit

contracts/libraries/LibFees.sol

@@ -57,4 +57,15 @@ library LibFees {
     emit AnnualFeeChanged(P2Storage.load().annualFee, _newFee);
     P2Storage.load().annualFee = _newFee;
   }
+
+  function setExitFee(uint256 _fee) internal  {
+    require(_fee <= 10**17, "FEE_TOO_BIG"); // max 10%
+    P2Storage.load().exitFee = _fee;
+  }
+
+  function setExitFeeRecipientShare(uint256 _share) internal {
+    require(_share <= 10**18, "FEE_SHARE_TOO_BIG");
+    P2Storage.load().exitFeeRecipientShare = _share;
+  }
+
 }

contracts/libraries/LibPoolEntryExit.sol

@@ -2,6 +2,7 @@ pragma solidity 0.6.4;
 
 import {PBasicSmartPoolStorage as PBStorage} from "../storage/PBasicSmartPoolStorage.sol";
 import {PCTokenStorage as PCStorage} from "../storage/PCTokenStorage.sol";
+import {PV2SmartPoolStorage as P2Storage} from "../storage/PV2SmartPoolStorage.sol";
 import "./LibFees.sol";
 
 import "./LibPoolToken.sol";
@@ -42,9 +43,11 @@ library LibPoolEntryExit {
 
   function _exitPool(uint256 _amount, uint256[] memory _minAmountsOut) internal lockBPoolSwap {
     IBPool bPool = PBStorage.load().bPool;
+    P2Storage.StorageStruct storage ws = P2Storage.load();
     LibFees.chargeOutstandingAnnualFee();
+    uint256 feeAmount = _amount.bmul(ws.exitFee).bdiv(10**18);
     uint256 poolTotal = PCStorage.load().totalSupply;
-    uint256 ratio = _amount.bdiv(poolTotal);
+    uint256 ratio = _amount.bsub(feeAmount).bdiv(poolTotal);
     require(ratio != 0);
 
     LibPoolToken._burn(msg.sender, _amount);
@@ -64,6 +67,18 @@ library LibPoolEntryExit {
       emit LOG_EXIT(msg.sender, token, tokenAmountOut);
       LibUnderlying._pushUnderlying(token, msg.sender, tokenAmountOut, balance);
     }
+
+    if(
+      feeAmount != 0 &&
+      ws.exitFeeRecipientShare != 0 &&
+      ws.feeRecipient != address(0)
+    ) {
+      uint256 feeRecipientShare = feeAmount.mul(ws.exitFeeRecipientShare).div(10**18);
+      if(feeRecipientShare != 0) {
+        LibPoolToken._mint(ws.feeRecipient, feeRecipientShare);
+      }
+    }
+
     emit PoolExited(msg.sender, _amount);
   }
 

contracts/libraries/LibPoolMath.sol

@@ -282,6 +282,35 @@ library LibPoolMath {
     }
   }
 
+   /**
+        @notice Gets the underlying assets and amounts redeemed when exiting specific pool shares.
+        @param _amount Amount of pool shares to calculate the values for
+        @return tokens The addresses of the tokens
+        @return amounts The amounts of tokens redeemed when exiting that amount of pool shares
+    */
+  function calcTokensForAmountExit(uint256 _amount)
+    external
+    view
+    returns (address[] memory tokens, uint256[] memory amounts)
+  {
+    P2Storage.StorageStruct storage ws = P2Storage.load();
+    uint256 feeAmount = _amount.bmul(ws.exitFee).bdiv(10**18);
+
+    tokens = PBStorage.load().bPool.getCurrentTokens();
+    amounts = new uint256[](tokens.length);
+    uint256 ratio = _amount.bsub(feeAmount).bdiv(
+      PCStorage.load().totalSupply.badd(LibFees.calcOutstandingAnnualFee())
+    );
+
+    for (uint256 i = 0; i < tokens.length; i++) {
+      address t = tokens[i];
+
+      uint256 bal = PBStorage.load().bPool.getBalance(t);
+      uint256 amount = ratio.bmul(bal);
+      amounts[i] = amount;
+    }
+  }
+
   /**
     @notice Calculate the amount of pool tokens out for a given amount in
     @param _token Address of the input token

contracts/smart-pools/PV2SmartPool.sol

@@ -483,6 +483,22 @@ contract PV2SmartPool is IPV2SmartPool, PCToken, ReentryProtection {
     LibFees.setFeeRecipient(_newRecipient);
   }
 
+  /**
+    @notice Sets the exit fee percentage. Can only be set by the current controller
+    @param _fee Fee percentage, max 10 percent
+  */
+  function setExitFee(uint256 _fee) external override onlyController noReentry {
+    LibFees.setExitFee(_fee);
+  }
+
+  /**
+    @notice Sets the recipient fee percentage share. Can only be set by the current controller
+    @param _share Percentage of fee for the recipient
+  */
+  function setExitFeeRecipientShare(uint256 _share) external override onlyController noReentry {
+    LibFees.setExitFeeRecipientShare(_share);
+  }
+
   /**
     @notice Trip the circuit breaker which disabled exit, join and swaps
   */
@@ -575,6 +591,21 @@ contract PV2SmartPool is IPV2SmartPool, PCToken, ReentryProtection {
     return LibPoolMath.calcTokensForAmount(_amount);
   }
 
+  /**
+        @notice Gets the underlying assets and amounts redeemed when exiting specific pool shares.
+        @param _amount Amount of pool shares to calculate the values for
+        @return tokens The addresses of the tokens
+        @return amounts The amounts of tokens redeemed when exiting that amount of pool shares
+    */
+  function calcTokensForAmountExit(uint256 _amount)
+    external
+    override
+    view
+    returns (address[] memory tokens, uint256[] memory amounts)
+  {
+    return LibPoolMath.calcTokensForAmountExit(_amount);
+  }
+
   /**
     @notice Calculate the amount of pool tokens out for a given amount in
     @param _token Address of the input token
@@ -645,7 +676,7 @@ contract PV2SmartPool is IPV2SmartPool, PCToken, ReentryProtection {
 
   /**
     @notice Get the address of the controller
-    @return The address of the pool
+    @return The address of the controller
   */
   function getController() external override view returns (address) {
     return PBStorage.load().controller;
@@ -699,6 +730,14 @@ contract PV2SmartPool is IPV2SmartPool, PCToken, ReentryProtection {
     return P2Storage.load().feeRecipient;
   }
 
+  function getExitFeeRecipientShare() external override view returns (uint256) {
+    return P2Storage.load().exitFeeRecipientShare;
+  }
+
+  function getExitFee() external override view returns (uint256) {
+    return P2Storage.load().exitFee;
+  }
+
   /**
     @notice Get the denormalized weight of a specific token in the underlying balancer pool
     @return the normalized weight of the token in uint

contracts/storage/PV2SmartPoolStorage.sol

@@ -14,6 +14,8 @@ library PV2SmartPoolStorage {
     uint256 lastAnnualFeeClaimed;
     address feeRecipient;
     address circuitBreaker;
+    uint256 exitFeeRecipientShare;
+    uint256 exitFee;
   }
 
   struct NewToken {

test/advancedPoolFunctionality.ts

@@ -780,7 +780,23 @@ describe("Advanced Pool Functionality", function () {
         expect(feeRecipientPoolBalanceAfter).to.eq(expectedMint);
       });
     });
-  });
+    describe("Exit fee", async () => {
+      it("Setting the exit fee should work", async () => {
+        const tenPercent = parseEther("0.1"); // 10%
+
+        await smartpool.setExitFee("1");
+        expect(await smartpool.getExitFee()).to.eq("1");
+        expect(smartpool.setExitFee(tenPercent.add(1))).to.be.revertedWith("FEE_TOO_BIG");
+      });
+      it("Setting the exit fee recipient share should work", async () => {
+        const hundrerdPercent = constants.One.mul(10).pow(18) // 100%
+
+        await smartpool.setExitFeeRecipientShare("1");
+        expect(await smartpool.getExitFeeRecipientShare()).to.eq("1");
+        expect(smartpool.setExitFeeRecipientShare(hundrerdPercent.add(1))).to.be.revertedWith("FEE_SHARE_TOO_BIG");
+      });
+    })
+   });
 });
 
 function createBigNumberArray(length: number, value: BigNumber): BigNumber[] {