contract NoMintRewardPool is StablePoolProxy, LPTokenWrapper, IRewardDistributionRecipient {

    using Address for address;

    IERC20 public rewardToken;
    uint256 public duration; // making it not a constant is less gas efficient, but portable

    uint256 public periodFinish = 0;
    uint256 public rewardRate = 0;
    uint256 public lastUpdateTime;
    uint256 public rewardPerTokenStored;
    mapping(address => uint256) public userRewardPerTokenPaid;
    mapping(address => uint256) public rewards;

    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    event Withdrawn(address indexed user, uint256 amount);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 RewardDenied(address indexed user, uint256 reward);

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

    // [Hardwork] setting the reward, lpToken, duration, and rewardDistribution for each pool
    function setReward(address _rewardToken,
        address _lpToken,
        uint256 _duration,
        address _rewardDistribution) public
    {
        require(address(lpToken) == address(0));
        rewardToken = IERC20(_rewardToken);
        lpToken = IERC20(_lpToken);
        duration = _duration;
        rewardDistribution = _rewardDistribution;
    }

    function lastTimeRewardApplicable() public view returns (uint256) {
        return Math.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]);
    }

    // stake visibility is public as overriding LPTokenWrapper's stake() function
    function stake(uint256 amount) public updateReward(msg.sender) {
        require(amount > 0, "Cannot stake 0");
        super.stake(amount);
        emit Staked(msg.sender, amount);
    }

    function withdraw(uint256 amount) public updateReward(msg.sender) {
        require(amount > 0, "Cannot withdraw 0");
        super.withdraw(amount);
        emit Withdrawn(msg.sender, amount);
    }

    function exit() external {
        withdraw(balanceOf(msg.sender));
        getReward();
    }

    function getReward() public updateReward(msg.sender) {
        uint256 reward = earned(msg.sender);
        if (reward > 0) {
            rewards[msg.sender] = 0;
            // If it is a normal user and not smart contract,
            // then the requirement will pass
            // If it is a smart contract, then
            // make sure that it is not on our greyList.
            if (tx.origin == msg.sender) {
                rewardToken.safeTransfer(msg.sender, reward);
                emit RewardPaid(msg.sender, reward);
            } else {
                emit RewardDenied(msg.sender, reward);
            }
        }
    }

    function notifyRewardAmount(uint256 reward)
        external
        onlyRewardDistribution
        updateReward(address(0))
    {
        if (block.timestamp >= periodFinish) {
            rewardRate = reward.div(duration);
        } else {
            uint256 remaining = periodFinish.sub(block.timestamp);
            uint256 leftover = remaining.mul(rewardRate);
            rewardRate = reward.add(leftover).div(duration);
        }
        lastUpdateTime = block.timestamp;
        periodFinish = block.timestamp.add(duration);
        emit RewardAdded(reward);
    }
}
/*
 *   [Hardwork]
 *   This pool doesn't mint.
 *   the rewards should be first transferred to this pool, then get "notified"
 *   by calling `notifyRewardAmount`
 */
function setReward(address _rewardToken,
        address _lpToken,
        uint256 _duration,
        address _rewardDistribution) public
    {
        require(address(lpToken) == address(0));
        rewardToken = IERC20(_rewardToken);
        lpToken = IERC20(_lpToken);
        duration = _duration;
        rewardDistribution = _rewardDistribution;
    }
// [Hardwork] setting the reward, lpToken, duration, and rewardDistribution for each pool