pragma solidity ^0.5.17;

interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function decimals() external view returns (uint);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;

        return c;
    }
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

library Address {
    function isContract(address account) internal view returns (bool) {
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != 0x0 && codehash != accountHash);
    }
    function toPayable(address account) internal pure returns (address payable) {
        return address(uint160(account));
    }
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-call-value
        (bool success, ) = recipient.call.value(amount)("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
}

library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }
    function callOptionalReturn(IERC20 token, bytes memory data) private {
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}

interface Controller {
    function vaults(address) external view returns (address);
    function rewards() external view returns (address);
}

interface StakingRewardsPool {
    function withdrawToken(address, uint256) external;
}

contract StrategyStakingWING {
    using SafeERC20 for IERC20;
    using Address for address;
    using SafeMath for uint256;
    
    address constant public want = address(0xcB3df3108635932D912632ef7132d03EcFC39080);
    
    uint256 public constant DURATION = 30 days;

    uint256 public lastUpdateTime;

    uint256 public amountLocked = 0;
    uint256 public rewards = 0;

    uint public withdrawalFee = 50;
    uint constant public withdrawalMax = 10000;

    uint public rewardRate = 35;
    uint constant public rewardRateMax = 10000;
    
    address public governance;
    address public controller;
    address public strategist;
    address public rewardsPool = address(0xB6eCc90cC20959Fcf0083bF353977c52e48De2c4);
    
    modifier updateReward() {
        rewards = earned();
        lastUpdateTime = currentTime();
        _;
    }

    constructor(address _controller) public {
        governance = msg.sender;
        controller = _controller;
    }
    
    function getName() external pure returns (string memory) {
        return "StrategyStakingWING";
    }

    function currentTime() public view returns (uint256) {
        return block.timestamp;
    }

    function earned() public view returns (uint256) {
        return
            amountLocked
                .mul(currentTime() - lastUpdateTime)
                .div(DURATION)
                .mul(rewardRate).div(rewardRateMax)
                .add(rewards);
    }

    function deposit() public updateReward {
        amountLocked = IERC20(want).balanceOf(address(this));
    }
    
    // Withdraw partial funds, normally used with a vault withdrawal
    function withdraw(uint _amount) external updateReward {
        require(msg.sender == controller, "!controller");

        address _vault = Controller(controller).vaults(address(want));
        require(_vault != address(0), "!vault"); // additional protection so we don't burn the funds
        
        uint _rewardToUser = _amount.mul(earned()).div(balanceOfWant());
        rewards = rewards - _rewardToUser;
        
        StakingRewardsPool(rewardsPool).withdrawToken(want, _rewardToUser);

        uint _fee = _rewardToUser.mul(withdrawalFee).div(withdrawalMax);
        
        IERC20(want).safeTransfer(Controller(controller).rewards(), _fee);
        
        IERC20(want).safeTransfer(_vault, _amount.sub(_fee));
        
        amountLocked = balanceOfWant();
    }
    
    // Controller only function for creating additional rewards from dust
    function withdraw(IERC20 _asset) external returns (uint balance) {
        require(msg.sender == controller, "!controller");
        require(want != address(_asset), "want");
        balance = _asset.balanceOf(address(this));
        _asset.safeTransfer(controller, balance);
    }

    // Withdraw all funds, normally used when migrating strategies
    function withdrawAll() external updateReward returns (uint balance) {
        require(msg.sender == controller, "!controller");
        
        StakingRewardsPool(rewardsPool).withdrawToken(want, rewards);
        rewards = 0;
        balance = IERC20(want).balanceOf(address(this));
        
        address _vault = Controller(controller).vaults(address(want));
        require(_vault != address(0), "!vault"); // additional protection so we don't burn the funds
        IERC20(want).safeTransfer(_vault, balance);
    }

    function balanceOfWant() public view returns (uint) {
        return IERC20(want).balanceOf(address(this));
    }

    function balanceOf() public view returns (uint) {
        return balanceOfWant() + earned();
    }
    
    function setGovernance(address _governance) external {
        require(msg.sender == governance, "!governance");
        governance = _governance;
    }
    
    function setController(address _controller) external {
        require(msg.sender == governance, "!governance");
        controller = _controller;
    }

    function setRewardsPool(address _rewardsPool) external {
        require(msg.sender == governance, "!governance");
        rewardsPool = _rewardsPool;
    }

    function setWithdrawalFee(uint _withdrawalFee) external {
        require(msg.sender == governance, "!governance");
        withdrawalFee = _withdrawalFee;
    }

    function setRewardRate(uint _rewardRate) external {
        require(msg.sender == governance, "!governance");
        rewardRate = _rewardRate;
    }
}