feat(PRT): Add Prt and PrtFeeSplitExtension

contracts/adapters/FeeSplitExtension.sol

@@ -91,7 +91,7 @@ contract FeeSplitExtension is BaseExtension, TimeLockUpgrade, MutualUpgrade {
      * will automatically be sent to this address so reading the balance of the SetToken in the contract after accrual is
      * sufficient for accounting for all collected fees.
      */
-    function accrueFeesAndDistribute() public {
+    function accrueFeesAndDistribute() public virtual {
         // Emits a FeeActualized event
         streamingFeeModule.accrueFee(setToken);
 
@@ -260,6 +260,7 @@ contract FeeSplitExtension is BaseExtension, TimeLockUpgrade, MutualUpgrade {
      */
     function updateFeeSplit(uint256 _newFeeSplit)
         external
+        virtual
         mutualUpgrade(manager.operator(), manager.methodologist())
     {
         require(_newFeeSplit <= PreciseUnitMath.preciseUnit(), "Fee must be less than 100%");

contracts/adapters/PrtFeeSplitExtension.sol

@@ -0,0 +1,137 @@
+/*
+    Copyright 2024 Index Cooperative
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+
+    SPDX-License-Identifier: Apache License, Version 2.0
+*/
+
+pragma solidity 0.6.10;
+pragma experimental ABIEncoderV2;
+
+import { Address } from "@openzeppelin/contracts/utils/Address.sol";
+import { SafeMath } from "@openzeppelin/contracts/math/SafeMath.sol";
+
+import { FeeSplitExtension } from "./FeeSplitExtension.sol";
+import { IBaseManager } from "../interfaces/IBaseManager.sol";
+import { IIssuanceModule } from "../interfaces/IIssuanceModule.sol";
+import { IPrt } from "../interfaces/IPrt.sol";
+import { IPrtStakingPool } from "../interfaces/IPrtStakingPool.sol";
+import { IStreamingFeeModule } from "../interfaces/IStreamingFeeModule.sol";
+import { PreciseUnitMath } from "../lib/PreciseUnitMath.sol";
+
+/**
+ * @title PrtFeeSplitExtension
+ * @dev Extension that allows for splitting and setting streaming and mint/redeem fees with a 
+ * PRT Staking Pool. The operator can accrue fees from the streaming fee module and distribute
+ * them to the operator and the PRT Staking Pool, snapshotting the PRT Staking Pool. The operator 
+ * can update the PRT staking pool address and the fee split between the operator and the 
+ * PRT staking pool. 
+ */
+contract PrtFeeSplitExtension is FeeSplitExtension {
+    using Address for address;
+    using PreciseUnitMath for uint256;
+    using SafeMath for uint256;
+
+    /* ============ Events ============ */
+
+    event PrtFeesDistributed(
+        address indexed operatorFeeRecipient,
+        address indexed prtStakingPool,
+        uint256 operatorTake,
+        uint256 prtTake
+    );
+
+    /* ============ State Variables ============ */
+
+    IPrt public prt;
+    IPrtStakingPool public prtStakingPool;
+
+    /* ============ Constructor ============ */
+
+    constructor(
+        IBaseManager _manager,
+        IStreamingFeeModule _streamingFeeModule,
+        IIssuanceModule _issuanceModule,
+        uint256 _operatorFeeSplit,
+        address _operatorFeeRecipient,
+        IPrt _prt
+    )
+        public
+        FeeSplitExtension(
+            _manager,
+            _streamingFeeModule,
+            _issuanceModule,
+            _operatorFeeSplit,
+            _operatorFeeRecipient
+        )
+    {
+        require(_prt.setToken() == address(manager.setToken()), "SetToken mismatch with Prt");
+        prt = _prt;
+    }
+
+    /* ============ External Functions ============ */
+
+    /**
+     * @notice ONLY OPERATOR: Updates PRT staking pool. PRT staking pool must have this extension set as the feeSplitExtension.
+     * @param _prtStakingPool Address of the new PRT staking pool
+     */
+    function updatePrtStakingPool(IPrtStakingPool _prtStakingPool) external onlyOperator {
+        require(address(_prtStakingPool) != address(0), "Zero address not valid");
+        require(_prtStakingPool.feeSplitExtension() == address(this), "PrtFeeSplitExtension must be set");
+        prtStakingPool = _prtStakingPool;
+    }
+
+    /**
+     * @notice ONLY OPERATOR: Accrues fees from streaming fee module. Gets resulting balance after fee accrual, calculates fees for
+     * operator and PRT staking pool, and sends to operator fee recipient and PRT Staking Pool respectively. NOTE: mint/redeem fees
+     * will automatically be sent to this address so reading the balance of the SetToken in the contract after accrual is
+     * sufficient for accounting for all collected fees. If the PRT take is greater than 0, the PRT Staking Pool will accrue the fees
+     * and update the snapshot.
+     */
+    function accrueFeesAndDistribute() public override onlyOperator {
+        // Emits a FeeActualized event
+        streamingFeeModule.accrueFee(setToken);
+
+        uint256 totalFees = setToken.balanceOf(address(this));
+
+        uint256 operatorTake = totalFees.preciseMul(operatorFeeSplit);
+        uint256 prtTake = totalFees.sub(operatorTake);
+
+        if (operatorTake > 0) {
+            setToken.transfer(operatorFeeRecipient, operatorTake);
+        }
+
+        // Accrue PRT Staking Pool rewards and update snapshot
+        if (prtTake > 0) {
+            setToken.approve(address(prtStakingPool), prtTake);
+            prtStakingPool.accrue(prtTake);
+        }
+
+        emit PrtFeesDistributed(operatorFeeRecipient, address(prtStakingPool), operatorTake, prtTake);
+    }
+
+    /**
+     * @notice Updates fee split between operator and PRT Staking Pool. Split defined in precise units (1% = 10^16).
+     * Does not accrue fees and snapshot PRT Staking Pool.
+     * @param _newFeeSplit Percent of fees in precise units (10^16 = 1%) sent to operator, (rest go to the PRT Staking Pool).
+     */
+    function updateFeeSplit(uint256 _newFeeSplit)
+        external
+        override
+        onlyOperator
+    {
+        require(_newFeeSplit <= PreciseUnitMath.preciseUnit(), "Fee must be less than 100%");
+        operatorFeeSplit = _newFeeSplit;
+    }
+}

contracts/interfaces/IPrt.sol

@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: Apache License, Version 2.0
+pragma solidity 0.6.10;
+
+import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
+
+interface IPrt is IERC20 {
+    function setToken() external view returns (address);
+}

contracts/interfaces/IPrtStakingPool.sol

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: Apache License, Version 2.0
+pragma solidity ^0.6.10;
+
+interface IPrtStakingPool {
+    function stake(uint256 _amount) external;
+    function unstake(uint256 _amount) external;
+    function accrue(uint256 _amount) external;
+    function claim() external;
+    function setFeeSplitExtension(address _feeSplitExtension) external;
+    function getCurrentId() external view returns (uint256); 
+    function getPendingRewards(address _account) external view returns (uint256); 
+    function getSnapshotRewards(uint256 _snapshotId, address _account) external view returns (uint256);
+    function feeSplitExtension() external view returns (address);
+    function prt() external view returns (address);
+}