BaseRewardPool.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
/**
 *Submitted for verification at Etherscan.io on 2020-07-17
 */

/*
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  / __/__ __ ___  / /_ / /  ___  / /_ (_)__ __
 _\ \ / // // _ \/ __// _ \/ -_)/ __// / \ \ /
/___/ \_, //_//_/\__//_//_/\__/ \__//_/ /_\_\
     /___/

* Synthetix: BaseRewardPool.sol
*
* Docs: https://docs.synthetix.io/
*
*
* MIT License
* ===========
*
* Copyright (c) 2020 Synthetix
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
*/

import "./Interfaces.sol";
import "./interfaces/MathUtil.sol";
import "@openzeppelin/contracts-0.6/math/SafeMath.sol";
import "@openzeppelin/contracts-0.6/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts-0.6/utils/Address.sol";
import "@openzeppelin/contracts-0.6/token/ERC20/SafeERC20.sol";


/**
 * @title   BaseRewardPool
 * @author  Synthetix -> ConvexFinance => AuraFinance
 * @notice  Unipool rewards contract that is re-deployed from rFactory for each staking pool.
 * @dev     Changes made here by ConvexFinance are to do with the delayed reward allocation. Curve is queued for
 *          rewards and the distribution only begins once the new rewards are sufficiently large, or the epoch
 *          has ended. Additionally, enables hooks for `extraRewards` that can be enabled at any point to
 *          distribute a child reward token (i.e. a secondary one from Curve, or a seperate one).
 *
 *          **************************** ¡¡¡ WARNING !!! **************************** 
 *          Any `extraRewards` is distributed by a VirtualBalanceRewardPool, which is linked to a StashToken,
 *          the StashToken wraps the `extraReward` as a `baseToken`.
 *          The StashToken is not ERC20 compliant, it is designed to interact only with VirtualBalanceRewardPool
 *          and ExtraRewardStashV3. 
 *          **************************** ¡¡¡ WARNING !!! **************************** 
 */
contract BaseRewardPool {
     using SafeMath for uint256;
    using SafeERC20 for IERC20;

    IERC20 public immutable rewardToken;
    IERC20 public immutable stakingToken;
    uint256 public constant duration = 7 days;

    address public immutable operator;
    address public immutable rewardManager;

    uint256 public immutable pid;
    uint256 public periodFinish = 0;
    uint256 public rewardRate = 0;
    uint256 public lastUpdateTime;
    uint256 public rewardPerTokenStored;
    uint256 public queuedRewards = 0;
    uint256 public currentRewards = 0;
    uint256 public historicalRewards = 0;
    uint256 public constant newRewardRatio = 830;
    uint256 private _totalSupply;
    mapping(address => uint256) public userRewardPerTokenPaid;
    mapping(address => uint256) public rewards;
    mapping(address => uint256) internal _balances;

    address[] public extraRewards;

    event RewardAdded(uint256 reward);
    event Staked(address indexed user, uint256 amount);
    event Withdrawn(address indexed user, uint256 amount);
    event RewardPaid(address indexed user, uint256 reward);
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev This is called directly from RewardFactory
     * @param pid_           Effectively the pool identifier - used in the Booster
     * @param stakingToken_  Pool LP token
     * @param rewardToken_   Crv
     * @param operator_      Booster
     * @param rewardManager_ RewardFactory
     */
    constructor(
        uint256 pid_,
        address stakingToken_,
        address rewardToken_,
        address operator_,
        address rewardManager_
    ) public {
        pid = pid_;
        stakingToken = IERC20(stakingToken_);
        rewardToken = IERC20(rewardToken_);
        operator = operator_;
        rewardManager = rewardManager_;
    }

    function totalSupply() public view virtual returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view virtual returns (uint256) {
        return _balances[account];
    }

    function extraRewardsLength() external view returns (uint256) {
        return extraRewards.length;
    }

    /**
     * @notice  Add extra rewards to the pool.
     * @dev Extra rewards are distributed by a VirtualRewardsPool's rewardToken,
     *      The rewardToken is a non-ERC20 StashToken contract that wraps the extra reward.
     *      The actual ERC20 extra reward can be retrivied as follows:
     *      - VirtualBalanceRewardPool.rewardToken => StashToken.baseToken.
     * @param _reward The VirtualRewardsPool address.
     */
    function addExtraReward(address _reward) external returns(bool){ 
        require(msg.sender == rewardManager, "!authorized");
        require(_reward != address(0),"!reward setting");
        
        if(extraRewards.length >= 12){
            return false;
        }
        
        extraRewards.push(_reward);
        return true;
    }
    function clearExtraRewards() external{
        require(msg.sender == rewardManager, "!authorized");
        delete extraRewards;
    }

    modifier updateReward(address account) {
        rewardPerTokenStored = rewardPerToken();
        lastUpdateTime = lastTimeRewardApplicable();
        if (account != address(0)) {
            rewards[account] = earned(account);
            userRewardPerTokenPaid[account] = rewardPerTokenStored;
        }
        _;
    }

    function lastTimeRewardApplicable() public view returns (uint256) {
        return MathUtil.min(block.timestamp, periodFinish);
    }

    function rewardPerToken() public view returns (uint256) {
        if (totalSupply() == 0) {
            return rewardPerTokenStored;
        }
        return
            rewardPerTokenStored.add(
                lastTimeRewardApplicable()
                    .sub(lastUpdateTime)
                    .mul(rewardRate)
                    .mul(1e18)
                    .div(totalSupply())
            );
    }

    function earned(address account) public view returns (uint256) {
        return
            balanceOf(account)
                .mul(rewardPerToken().sub(userRewardPerTokenPaid[account]))
                .div(1e18)
                .add(rewards[account]);
    }

    function stake(uint256 _amount)
        public 
        returns(bool)
    {
        _processStake(_amount, msg.sender);

        stakingToken.safeTransferFrom(msg.sender, address(this), _amount);
        emit Staked(msg.sender, _amount);

        return true;
    }

    function stakeAll() external returns(bool){
        uint256 balance = stakingToken.balanceOf(msg.sender);
        stake(balance);
        return true;
    }

    function stakeFor(address _for, uint256 _amount)
        public
        returns(bool)
    {
        _processStake(_amount, _for);

        //take away from sender
        stakingToken.safeTransferFrom(msg.sender, address(this), _amount);
        emit Staked(_for, _amount);
        
        return true;
    }

    /**
     * @dev Generic internal staking function that basically does 3 things: update rewards based
     *      on previous balance, trigger also on any child contracts, then update balances.
     * @param _amount    Units to add to the users balance
     * @param _receiver  Address of user who will receive the stake
     */
    function _processStake(uint256 _amount, address _receiver) internal updateReward(_receiver) {
        require(_amount > 0, 'RewardPool : Cannot stake 0');
        
        //also stake to linked rewards
        for(uint i=0; i < extraRewards.length; i++){
            IRewards(extraRewards[i]).stake(_receiver, _amount);
        }

        _totalSupply = _totalSupply.add(_amount);
        _balances[_receiver] = _balances[_receiver].add(_amount);

        emit Transfer(address(0), _receiver, _amount);
    }

    function withdraw(uint256 amount, bool claim)
        public
        updateReward(msg.sender)
        returns(bool)
    {
        require(amount > 0, 'RewardPool : Cannot withdraw 0');

        //also withdraw from linked rewards
        for(uint i=0; i < extraRewards.length; i++){
            IRewards(extraRewards[i]).withdraw(msg.sender, amount);
        }

        _totalSupply = _totalSupply.sub(amount);
        _balances[msg.sender] = _balances[msg.sender].sub(amount);

        stakingToken.safeTransfer(msg.sender, amount);
        emit Withdrawn(msg.sender, amount);
     
        if(claim){
            getReward(msg.sender,true);
        }

        emit Transfer(msg.sender, address(0), amount);

        return true;
    }

    function withdrawAll(bool claim) external{
        withdraw(_balances[msg.sender],claim);
    }

    function withdrawAndUnwrap(uint256 amount, bool claim) public returns(bool){
        _withdrawAndUnwrapTo(amount, msg.sender, msg.sender);
        //get rewards too
        if(claim){
            getReward(msg.sender,true);
        }
        return true;
    }

    function _withdrawAndUnwrapTo(uint256 amount, address from, address receiver) internal updateReward(from) returns(bool){
        //also withdraw from linked rewards
        for(uint i=0; i < extraRewards.length; i++){
            IRewards(extraRewards[i]).withdraw(from, amount);
        }
        
        _totalSupply = _totalSupply.sub(amount);
        _balances[from] = _balances[from].sub(amount);

        //tell operator to withdraw from here directly to user
        IDeposit(operator).withdrawTo(pid,amount,receiver);
        emit Withdrawn(from, amount);

        emit Transfer(from, address(0), amount);

        return true;
    }

    function withdrawAllAndUnwrap(bool claim) external{
        withdrawAndUnwrap(_balances[msg.sender],claim);
    }

    /**
     * @dev Gives a staker their rewards, with the option of claiming extra rewards
     * @param _account     Account for which to claim
     * @param _claimExtras Get the child rewards too?
     */
    function getReward(address _account, bool _claimExtras) public updateReward(_account) returns(bool){
        uint256 reward = earned(_account);
        if (reward > 0) {
            rewards[_account] = 0;
            rewardToken.safeTransfer(_account, reward);
            IDeposit(operator).rewardClaimed(pid, _account, reward);
            emit RewardPaid(_account, reward);
        }

        //also get rewards from linked rewards
        if(_claimExtras){
            for(uint i=0; i < extraRewards.length; i++){
                IRewards(extraRewards[i]).getReward(_account);
            }
        }
        return true;
    }

    /**
     * @dev Called by a staker to get their allocated rewards
     */
    function getReward() external returns(bool){
        getReward(msg.sender,true);
        return true;
    }

    /**
     * @dev Processes queued rewards in isolation, providing the period has finished.
     *      This allows a cheaper way to trigger rewards on low value pools.
     */
    function processIdleRewards() external {
        if (block.timestamp >= periodFinish && queuedRewards > 0) {
            notifyRewardAmount(queuedRewards);
            queuedRewards = 0;
        }
    }

    /**
     * @dev Called by the booster to allocate new Crv rewards to this pool
     *      Curve is queued for rewards and the distribution only begins once the new rewards are sufficiently
     *      large, or the epoch has ended.
     */
    function queueNewRewards(uint256 _rewards) external returns(bool){
        require(msg.sender == operator, "!authorized");

        _rewards = _rewards.add(queuedRewards);

        if (block.timestamp >= periodFinish) {
            notifyRewardAmount(_rewards);
            queuedRewards = 0;
            return true;
        }

        //et = now - (finish-duration)
        uint256 elapsedTime = block.timestamp.sub(periodFinish.sub(duration));
        //current at now: rewardRate * elapsedTime
        uint256 currentAtNow = rewardRate * elapsedTime;
        uint256 queuedRatio = currentAtNow.mul(1000).div(_rewards);

        //uint256 queuedRatio = currentRewards.mul(1000).div(_rewards);
        if(queuedRatio < newRewardRatio){
            notifyRewardAmount(_rewards);
            queuedRewards = 0;
        }else{
            queuedRewards = _rewards;
        }
        return true;
    }

    function notifyRewardAmount(uint256 reward)
        internal
        updateReward(address(0))
    {
        historicalRewards = historicalRewards.add(reward);
        if (block.timestamp >= periodFinish) {
            rewardRate = reward.div(duration);
        } else {
            uint256 remaining = periodFinish.sub(block.timestamp);
            uint256 leftover = remaining.mul(rewardRate);
            reward = reward.add(leftover);
            rewardRate = reward.div(duration);
        }
        currentRewards = reward;
        lastUpdateTime = block.timestamp;
        periodFinish = block.timestamp.add(duration);
        emit RewardAdded(reward);
    }
}