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       1                 :             : // SPDX-License-Identifier: BUSL-1.1
       2                 :             : pragma solidity ^0.8.10;
       3                 :             : 
       4                 :             : import {IStakedToken} from '../interfaces/IStakedToken.sol';
       5                 :             : import {IStakedTokenTransferStrategy} from '../interfaces/IStakedTokenTransferStrategy.sol';
       6                 :             : import {ITransferStrategyBase} from '../interfaces/ITransferStrategyBase.sol';
       7                 :             : import {TransferStrategyBase} from './TransferStrategyBase.sol';
       8                 :             : import {GPv2SafeERC20} from '../../dependencies/gnosis/contracts/GPv2SafeERC20.sol';
       9                 :             : import {IERC20} from '../../dependencies/openzeppelin/contracts/IERC20.sol';
      10                 :             : 
      11                 :             : /**
      12                 :             :  * @title StakedTokenTransferStrategy
      13                 :             :  * @notice Transfer strategy that stakes the rewards into a staking contract and transfers the staking contract token.
      14                 :             :  * The underlying token must be transferred to this contract to be able to stake it on demand.
      15                 :             :  * @author Aave
      16                 :             :  **/
      17                 :             : contract StakedTokenTransferStrategy is TransferStrategyBase, IStakedTokenTransferStrategy {
      18                 :             :   using GPv2SafeERC20 for IERC20;
      19                 :             : 
      20                 :             :   IStakedToken internal immutable STAKE_CONTRACT;
      21                 :             :   address internal immutable UNDERLYING_TOKEN;
      22                 :             : 
      23                 :             :   constructor(
      24                 :             :     address incentivesController,
      25                 :             :     address rewardsAdmin,
      26                 :             :     IStakedToken stakeToken
      27                 :             :   ) TransferStrategyBase(incentivesController, rewardsAdmin) {
      28                 :           0 :     STAKE_CONTRACT = stakeToken;
      29                 :           0 :     UNDERLYING_TOKEN = STAKE_CONTRACT.STAKED_TOKEN();
      30                 :             : 
      31                 :           0 :     IERC20(UNDERLYING_TOKEN).approve(address(STAKE_CONTRACT), 0);
      32                 :           0 :     IERC20(UNDERLYING_TOKEN).approve(address(STAKE_CONTRACT), type(uint256).max);
      33                 :             :   }
      34                 :             : 
      35                 :             :   /// @inheritdoc TransferStrategyBase
      36                 :             :   function performTransfer(
      37                 :             :     address to,
      38                 :             :     address reward,
      39                 :             :     uint256 amount
      40                 :             :   )
      41                 :             :     external
      42                 :             :     override(TransferStrategyBase, ITransferStrategyBase)
      43                 :             :     onlyIncentivesController
      44                 :             :     returns (bool)
      45                 :             :   {
      46                 :           1 :     require(reward == address(STAKE_CONTRACT), 'REWARD_TOKEN_NOT_STAKE_CONTRACT');
      47                 :             : 
      48                 :           1 :     STAKE_CONTRACT.stake(to, amount);
      49                 :             : 
      50                 :           1 :     return true;
      51                 :             :   }
      52                 :             : 
      53                 :             :   /// @inheritdoc IStakedTokenTransferStrategy
      54                 :             :   function renewApproval() external onlyRewardsAdmin {
      55                 :           1 :     IERC20(UNDERLYING_TOKEN).approve(address(STAKE_CONTRACT), 0);
      56                 :           1 :     IERC20(UNDERLYING_TOKEN).approve(address(STAKE_CONTRACT), type(uint256).max);
      57                 :             :   }
      58                 :             : 
      59                 :             :   /// @inheritdoc IStakedTokenTransferStrategy
      60                 :             :   function dropApproval() external onlyRewardsAdmin {
      61                 :           1 :     IERC20(UNDERLYING_TOKEN).approve(address(STAKE_CONTRACT), 0);
      62                 :             :   }
      63                 :             : 
      64                 :             :   /// @inheritdoc IStakedTokenTransferStrategy
      65                 :             :   function getStakeContract() external view returns (address) {
      66                 :           1 :     return address(STAKE_CONTRACT);
      67                 :             :   }
      68                 :             : 
      69                 :             :   /// @inheritdoc IStakedTokenTransferStrategy
      70                 :             :   function getUnderlyingToken() external view returns (address) {
      71                 :           1 :     return UNDERLYING_TOKEN;
      72                 :             :   }
      73                 :             : }