// SPDX-License-Identifier: MIT

pragma solidity ^0.6.2;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        return _functionCallWithValue(target, data, value, errorMessage);
    }

    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.12;

import '@openzeppelin/contracts/token/ERC20/IERC20.sol';

interface IDvd is IERC20 {

    function mint(address account, uint256 amount) external;

    function burn(address account, uint256 amount) external;

    function increaseShareholderPoint(address account, uint256 amount) external;

    function decreaseShareholderPoint(address account, uint256 amount) external;

    function shareholderPointOf(address account) external view returns (uint256);

    function totalShareholderPoint() external view returns (uint256);

}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.12;

interface ILordOfCoin {

    function marketOpenTime() external view returns (uint256);

    function dvd() external view returns (address);

    function sdvd() external view returns (address);

    function sdvdEthPairAddress() external view returns (address);

    function buy(uint256 musdAmount) external returns (uint256 recipientDVD, uint256 marketTax, uint256 curveTax, uint256 taxedDVD);

    function buyTo(address recipient, uint256 musdAmount) external returns (uint256 recipientDVD, uint256 marketTax, uint256 curveTax, uint256 taxedDVD);

    function buyFromETH() payable external returns (uint256 recipientDVD, uint256 marketTax, uint256 curveTax, uint256 taxedDVD);

    function sell(uint256 dvdAmount) external returns (uint256 returnedMUSD, uint256 marketTax, uint256 curveTax, uint256 taxedDVD);

    function sellTo(address recipient, uint256 dvdAmount) external returns (uint256 returnedMUSD, uint256 marketTax, uint256 curveTax, uint256 taxedDVD);

    function sellToETH(uint256 dvdAmount) external returns (uint256 returnedETH, uint256 returnedMUSD, uint256 marketTax, uint256 curveTax, uint256 taxedDVD);

    function claimDividend() external returns (uint256 net, uint256 fee);

    function claimDividendTo(address recipient) external returns (uint256 net, uint256 fee);

    function claimDividendETH() external returns (uint256 net, uint256 fee, uint256 receivedETH);

    function checkSnapshot() external;

    function releaseTreasury() external;

    function depositTradingProfit(uint256 amount) external;

}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.12;

import '@openzeppelin/contracts/token/ERC20/IERC20.sol';

interface ISDvd is IERC20 {

    function mint(address account, uint256 amount) external;

    function burn(address account, uint256 amount) external;

    function setMinter(address account, bool value) external;

    function setNoFeeAddress(address account, bool value) external;

    function setPairAddress(address _pairAddress) external;

    function snapshot() external returns (uint256);

    function syncPairTokenTotalSupply() external returns (bool isPairTokenBurned);

}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.12;

interface ITreasury {

    function release() external;

}

// SPDX-License-Identifier: Unlicensed

pragma solidity >=0.5.0;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);
    function migrator() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
    function setMigrator(address) external;
}

// SPDX-License-Identifier: Unlicensed

pragma solidity >=0.5.0;

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

// SPDX-License-Identifier: Unlicensed

pragma solidity >=0.6.2;

interface IUniswapV2Router01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

// SPDX-License-Identifier: Unlicensed

pragma solidity >=0.6.2;

import './IUniswapV2Router01.sol';

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
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);
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

import "../GSN/Context.sol";
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// SPDX-License-Identifier: Unlicensed

pragma solidity ^0.6.12;

import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import '@openzeppelin/contracts/token/ERC20/SafeERC20.sol';
import "@openzeppelin/contracts/math/Math.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "./interfaces/ILordOfCoin.sol";
import "./interfaces/IDvd.sol";
import "./interfaces/ISDvd.sol";
import "./interfaces/ITreasury.sol";

/// @dev Ownable is used because solidity complain trying to deploy a contract whose code is too large when everything is added into Lord of Coin contract.
/// The only owner function is `init` which is to setup for the first time after deployment.
/// After init finished, owner will be renounced automatically. owner() function will return 0x0 address.
abstract contract Pool is ReentrancyGuard, Ownable {

    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    event Staked(address indexed sender, address indexed recipient, uint256 amount);
    event Withdrawn(address indexed sender, address indexed recipient, uint256 amount);
    event Claimed(address indexed sender, address indexed recipient, uint256 net, uint256 tax, uint256 total);
    event Halving(uint256 amount);

    /// @dev Token will be DVD or SDVD-ETH UNI-V2
    address public stakedToken;
    ISDvd public sdvd;

    /// @notice Flag to determine if farm is open
    bool public isFarmOpen = false;
    /// @notice Farming will be open on this timestamp
    uint256 public farmOpenTime;

    uint256 public rewardAllocation;
    uint256 public rewardRate;
    uint256 public rewardDuration = 1460 days;  // halving per 4 years
    uint256 public lastUpdateTime;
    uint256 public rewardPerTokenStored;
    uint256 public finishTime;

    uint256 public bonusRewardAllocation;
    uint256 public bonusRewardRate;
    uint256 public bonusRewardDuration = 1 days; //  Reward bonus distributed every day, must be the same value with pool treasury release threshold
    uint256 public bonusLastUpdateTime;
    uint256 public bonusRewardPerTokenStored;
    uint256 public bonusRewardFinishTime;

    struct AccountInfo {
        // Staked token balance
        uint256 balance;
        // Normal farming reward
        uint256 reward;
        uint256 rewardPerTokenPaid;
        // Bonus reward from transaction fee
        uint256 bonusReward;
        uint256 bonusRewardPerTokenPaid;
    }

    /// @dev Account info
    mapping(address => AccountInfo) public accountInfos;

    /// @dev Total supply of staked tokens
    uint256 private _totalSupply;

    /// @notice Total rewards minted from this pool
    uint256 public totalRewardMinted;

    // @dev Lord of Coin
    address controller;

    // @dev Pool treasury
    address poolTreasury;

    constructor(address _poolTreasury, uint256 _farmOpenTime) public {
        poolTreasury = _poolTreasury;
        farmOpenTime = _farmOpenTime;
    }

    /* ========== Modifiers ========== */

    modifier onlyController {
        require(msg.sender == controller, 'Controller only');
        _;
    }

    modifier onlyPoolTreasury {
        require(msg.sender == poolTreasury, 'Treasury only');
        _;
    }

    modifier farmOpen {
        require(isFarmOpen, 'Farm not open');
        _;
    }

    /* ========== Owner Only ========== */

    /// @notice Setup for the first time after deploy and renounce ownership immediately
    function init(address _controller, address _stakedToken) external onlyOwner {
        controller = _controller;
        stakedToken = _stakedToken;
        sdvd = ISDvd(ILordOfCoin(_controller).sdvd());

        // Renounce ownership immediately after init
        renounceOwnership();
    }

    /* ========== Pool Treasury Only ========== */

    /// @notice Distribute bonus rewards to farmers
    /// @dev Can only be called by pool treasury
    function distributeBonusRewards(uint256 amount) external onlyPoolTreasury {
        // Set bonus reward allocation
        bonusRewardAllocation = amount;
        // Calculate bonus reward rate
        bonusRewardRate = bonusRewardAllocation.div(bonusRewardDuration);
        // Set finish time
        bonusRewardFinishTime = block.timestamp.add(bonusRewardDuration);
        // Set last update time
        bonusLastUpdateTime = block.timestamp;
    }

    /* ========== Mutative ========== */

    /// @notice Stake token.
    /// @dev Need to approve staked token first.
    /// @param amount Token amount.
    function stake(uint256 amount) external nonReentrant {
        _stake(msg.sender, msg.sender, amount);
    }

    /// @notice Stake token.
    /// @dev Need to approve staked token first.
    /// @param recipient Address who receive staked token balance.
    /// @param amount Token amount.
    function stakeTo(address recipient, uint256 amount) external nonReentrant {
        _stake(msg.sender, recipient, amount);
    }

    /// @notice Withdraw token.
    /// @param amount Token amount.
    function withdraw(uint256 amount) external nonReentrant farmOpen {
        _withdraw(msg.sender, msg.sender, amount);
    }

    /// @notice Withdraw token.
    /// @param recipient Address who receive staked token.
    /// @param amount Token amount.
    function withdrawTo(address recipient, uint256 amount) external nonReentrant farmOpen {
        _withdraw(msg.sender, recipient, amount);
    }

    /// @notice Claim SDVD reward
    /// @return Reward net amount
    /// @return Reward tax amount
    /// @return Total Reward amount
    function claimReward() external nonReentrant farmOpen returns(uint256, uint256, uint256) {
        return _claimReward(msg.sender, msg.sender);
    }

    /// @notice Claim SDVD reward
    /// @param recipient Address who receive reward.
    /// @return Reward net amount
    /// @return Reward tax amount
    /// @return Total Reward amount
    function claimRewardTo(address recipient) external nonReentrant farmOpen returns(uint256, uint256, uint256) {
        return _claimReward(msg.sender, recipient);
    }

    /* ========== Internal ========== */

    function _updateReward(address account) internal {
        rewardPerTokenStored = rewardPerToken();
        lastUpdateTime = lastTimeRewardApplicable();
        if (account != address(0)) {
            accountInfos[account].reward = earned(account);
            accountInfos[account].rewardPerTokenPaid = rewardPerTokenStored;
        }
    }

    function _updateBonusReward(address account) internal {
        bonusRewardPerTokenStored = bonusRewardPerToken();
        bonusLastUpdateTime = lastTimeBonusRewardApplicable();
        if (account != address(0)) {
            accountInfos[account].bonusReward = bonusEarned(account);
            accountInfos[account].bonusRewardPerTokenPaid = bonusRewardPerTokenStored;
        }
    }

    /// @notice Stake staked token
    /// @param sender address. Address who have the token.
    /// @param recipient address. Address who receive staked token balance.
    function _stake(address sender, address recipient, uint256 amount) internal virtual {
        _checkOpenFarm();
        _checkHalving();
        _updateReward(recipient);
        _updateBonusReward(recipient);
        _notifyController();

        require(amount > 0, 'Cannot stake 0');

        IERC20(stakedToken).safeTransferFrom(sender, address(this), amount);
        _totalSupply = _totalSupply.add(amount);
        accountInfos[recipient].balance = accountInfos[recipient].balance.add(amount);

        emit Staked(sender, recipient, amount);
    }

    /// @notice Withdraw staked token
    /// @param sender address. Address who have stake the token.
    /// @param recipient address. Address who receive the staked token.
    function _withdraw(address sender, address recipient, uint256 amount) internal virtual {
        _checkHalving();
        _updateReward(sender);
        _updateBonusReward(sender);
        _notifyController();

        require(amount > 0, 'Cannot withdraw 0');
        require(accountInfos[sender].balance >= amount, 'Insufficient balance');

        _totalSupply = _totalSupply.sub(amount);
        accountInfos[sender].balance = accountInfos[sender].balance.sub(amount);
        IERC20(stakedToken).safeTransfer(recipient, amount);

        emit Withdrawn(sender, recipient, amount);
    }

    /// @notice Claim reward
    /// @param sender address. Address who have stake the token.
    /// @param recipient address. Address who receive the reward.
    /// @return totalNetReward Total net SDVD reward.
    /// @return totalTaxReward Total taxed SDVD reward.
    /// @return totalReward Total SDVD reward.
    function _claimReward(address sender, address recipient) internal virtual returns(uint256 totalNetReward, uint256 totalTaxReward, uint256 totalReward) {
        _checkHalving();
        _updateReward(sender);
        _updateBonusReward(sender);
        _notifyController();

        uint256 reward = accountInfos[sender].reward;
        uint256 bonusReward = accountInfos[sender].bonusReward;
        totalReward = reward.add(bonusReward);
        require(totalReward > 0, 'No reward to claim');
        if (reward > 0) {
            // Reduce reward first
            accountInfos[sender].reward = 0;

            // Apply tax
            uint256 tax = reward.div(claimRewardTaxDenominator());
            uint256 net = reward.sub(tax);

            // Mint SDVD as reward to recipient
            sdvd.mint(recipient, net);
            // Mint SDVD tax to pool treasury
            sdvd.mint(address(poolTreasury), tax);

            // Increase total
            totalNetReward = totalNetReward.add(net);
            totalTaxReward = totalTaxReward.add(tax);
            // Set stats
            totalRewardMinted = totalRewardMinted.add(reward);
        }
        if (bonusReward > 0) {
            // Reduce bonus reward first
            accountInfos[sender].bonusReward = 0;
            // Get balance and check so we doesn't overrun
            uint256 balance = sdvd.balanceOf(address(this));
            if (bonusReward > balance) {
                bonusReward = balance;
            }

            // Apply tax
            uint256 tax = bonusReward.div(claimRewardTaxDenominator());
            uint256 net = bonusReward.sub(tax);

            // Send bonus reward to recipient
            IERC20(sdvd).safeTransfer(recipient, net);
            // Send tax to treasury
            IERC20(sdvd).safeTransfer(address(poolTreasury), tax);

            // Increase total
            totalNetReward = totalNetReward.add(net);
            totalTaxReward = totalTaxReward.add(tax);
        }
        if (totalReward > 0) {
            emit Claimed(sender, recipient, totalNetReward, totalTaxReward, totalReward);
        }
    }

    /// @notice Check if farm can be open
    function _checkOpenFarm() internal {
        require(farmOpenTime <= block.timestamp, 'Farm not open');
        if (!isFarmOpen) {
            // Set flag
            isFarmOpen = true;

            // Initialize
            lastUpdateTime = block.timestamp;
            finishTime = block.timestamp.add(rewardDuration);
            rewardRate = rewardAllocation.div(rewardDuration);

            // Initialize bonus
            bonusLastUpdateTime = block.timestamp;
            bonusRewardFinishTime = block.timestamp.add(bonusRewardDuration);
            bonusRewardRate = bonusRewardAllocation.div(bonusRewardDuration);
        }
    }

    /// @notice Check and do halving when finish time reached
    function _checkHalving() internal {
        if (block.timestamp >= finishTime) {
            // Halving reward
            rewardAllocation = rewardAllocation.div(2);
            // Calculate reward rate
            rewardRate = rewardAllocation.div(rewardDuration);
            // Set finish time
            finishTime = block.timestamp.add(rewardDuration);
            // Set last update time
            lastUpdateTime = block.timestamp;
            // Emit event
            emit Halving(rewardAllocation);
        }
    }

    /// @notice Check if need to increase snapshot in lord of coin
    function _notifyController() internal {
        ILordOfCoin(controller).checkSnapshot();
        ILordOfCoin(controller).releaseTreasury();
    }

    /* ========== View ========== */

    /// @notice Get staked token total supply
    function totalSupply() external view returns (uint256) {
        return _totalSupply;
    }

    /// @notice Get staked token balance
    function balanceOf(address account) external view returns (uint256) {
        return accountInfos[account].balance;
    }

    /// @notice Get full earned amount and bonus
    /// @dev Combine earned
    function fullEarned(address account) external view returns (uint256) {
        return earned(account).add(bonusEarned(account));
    }

    /// @notice Get full reward rate
    /// @dev Combine reward rate
    function fullRewardRate() external view returns (uint256) {
        return rewardRate.add(bonusRewardRate);
    }

    /// @notice Get claim reward tax
    function claimRewardTaxDenominator() public view returns (uint256) {
        if (block.timestamp < farmOpenTime.add(365 days)) {
            // 50% tax
            return 2;
        } else if (block.timestamp < farmOpenTime.add(730 days)) {
            // 33% tax
            return 3;
        } else if (block.timestamp < farmOpenTime.add(1095 days)) {
            // 25% tax
            return 4;
        } else if (block.timestamp < farmOpenTime.add(1460 days)) {
            // 20% tax
            return 5;
        } else {
            // 10% tax
            return 10;
        }
    }

    /// Normal rewards

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

    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 accountInfos[account].balance.mul(
            rewardPerToken().sub(accountInfos[account].rewardPerTokenPaid)
        )
        .div(1e18)
        .add(accountInfos[account].reward);
    }

    /// Bonus

    function lastTimeBonusRewardApplicable() public view returns (uint256) {
        return Math.min(block.timestamp, bonusRewardFinishTime);
    }

    function bonusRewardPerToken() public view returns (uint256) {
        if (_totalSupply == 0) {
            return bonusRewardPerTokenStored;
        }
        return bonusRewardPerTokenStored.add(
            lastTimeBonusRewardApplicable().sub(bonusLastUpdateTime).mul(bonusRewardRate).mul(1e18).div(_totalSupply)
        );
    }

    function bonusEarned(address account) public view returns (uint256) {
        return accountInfos[account].balance.mul(
            bonusRewardPerToken().sub(accountInfos[account].bonusRewardPerTokenPaid)
        )
        .div(1e18)
        .add(accountInfos[account].bonusReward);
    }

}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor () internal {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// SPDX-License-Identifier: Unlicensed

pragma solidity ^0.6.12;

import "./uniswapv2/interfaces/IUniswapV2Router02.sol";
import "./uniswapv2/interfaces/IUniswapV2Pair.sol";
import "./uniswapv2/interfaces/IUniswapV2Factory.sol";
import "./interfaces/IDvd.sol";
import "./Pool.sol";

contract SDvdEthPool is Pool {

    event StakedETH(address indexed account, uint256 amount);
    event ClaimedAndStaked(address indexed account, uint256 amount);

    /// @dev Uniswap router
    IUniswapV2Router02 uniswapRouter;

    /// @dev Uniswap factory
    IUniswapV2Factory uniswapFactory;

    /// @dev WETH address
    address weth;

    /// @notice LGE state
    bool public isLGEActive = true;

    /// @notice Max initial deposit cap
    uint256 public LGE_INITIAL_DEPOSIT_CAP = 5 ether;

    /// @notice Amount in SDVD. After hard cap reached, stake ETH will function as normal staking.
    uint256 public LGE_HARD_CAP = 200 ether;

    /// @dev Initial price multiplier
    uint256 public LGE_INITIAL_PRICE_MULTIPLIER = 2;

    constructor(address _poolTreasury, address _uniswapRouter, uint256 _farmOpenTime) public Pool(_poolTreasury, _farmOpenTime) {
        rewardAllocation = 240000 * 1e18;
        rewardAllocation = rewardAllocation.sub(LGE_HARD_CAP.div(2));
        uniswapRouter = IUniswapV2Router02(_uniswapRouter);
        uniswapFactory = IUniswapV2Factory(uniswapRouter.factory());
        weth = uniswapRouter.WETH();
    }

    /// @dev Added to receive ETH when swapping on Uniswap
    receive() external payable {
    }

    /// @notice Stake token using ETH conveniently.
    function stakeETH() external payable nonReentrant {
        _stakeETH(msg.value);
    }

    /// @notice Stake token using SDVD and ETH conveniently.
    /// @dev User must approve SDVD first
    function stakeSDVD(uint256 amountToken) external payable nonReentrant farmOpen {
        require(isLGEActive == false, 'LGE still active');

        uint256 pairSDVDBalance = IERC20(sdvd).balanceOf(stakedToken);
        uint256 pairETHBalance = IERC20(weth).balanceOf(stakedToken);
        uint256 amountETH = amountToken.mul(pairETHBalance).div(pairSDVDBalance);

        // Make sure received eth is enough
        require(msg.value >= amountETH, 'Not enough ETH');
        // Check if there is excess eth
        uint256 excessETH = msg.value.sub(amountETH);
        // Send back excess eth
        if (excessETH > 0) {
            msg.sender.transfer(excessETH);
        }

        // Transfer sdvd from sender to this contract
        IERC20(sdvd).safeTransferFrom(msg.sender, address(this), amountToken);

        // Approve uniswap router to spend SDVD
        IERC20(sdvd).approve(address(uniswapRouter), amountToken);
        // Add liquidity
        (,, uint256 liquidity) = uniswapRouter.addLiquidityETH{value : amountETH}(address(sdvd), amountToken, 0, 0, address(this), block.timestamp.add(30 minutes));

        // Approve self
        IERC20(stakedToken).approve(address(this), liquidity);
        // Stake LP token for sender
        _stake(address(this), msg.sender, liquidity);
    }

    /// @notice Claim reward and re-stake conveniently.
    function claimRewardAndStake() external nonReentrant farmOpen {
        require(isLGEActive == false, 'LGE still active');

        // Claim SDVD reward to this address
        (uint256 totalNetReward,,) = _claimReward(msg.sender, address(this));

        // Split total reward to be swapped
        uint256 swapAmountSDVD = totalNetReward.div(2);

        // Swap path
        address[] memory path = new address[](2);
        path[0] = address(sdvd);
        path[1] = weth;

        // Approve uniswap router to spend sdvd
        IERC20(sdvd).approve(address(uniswapRouter), swapAmountSDVD);
        // Swap SDVD to ETH
        // Param: uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline
        uint256[] memory amounts = uniswapRouter.swapExactTokensForETH(swapAmountSDVD, 0, path, address(this), block.timestamp.add(30 minutes));
        // Get received ETH amount from swap
        uint256 amountETHReceived = amounts[1];

        // Get pair address and balance
        uint256 pairSDVDBalance = IERC20(sdvd).balanceOf(stakedToken);
        uint256 pairETHBalance = IERC20(weth).balanceOf(stakedToken);

        // Get available SDVD
        uint256 amountSDVD = totalNetReward.sub(swapAmountSDVD);
        // Calculate how much ETH needed to provide liquidity
        uint256 amountETH = amountSDVD.mul(pairETHBalance).div(pairSDVDBalance);

        // If required ETH amount to add liquidity is bigger than what we have
        // Then we need to reduce SDVD amount
        if (amountETH > amountETHReceived) {
            // Set ETH amount
            amountETH = amountETHReceived;
            // Get amount SDVD needed to add liquidity
            uint256 amountSDVDRequired = amountETH.mul(pairSDVDBalance).div(pairETHBalance);
            // Send dust
            if (amountSDVD > amountSDVDRequired) {
                IERC20(sdvd).safeTransfer(msg.sender, amountSDVD.sub(amountSDVDRequired));
            }
            // Set SDVD amount
            amountSDVD = amountSDVDRequired;
        }
        // Else if we have too much ETH
        else if (amountETHReceived > amountETH) {
            // Send excess
            msg.sender.transfer(amountETHReceived.sub(amountETH));
        }

        // Approve uniswap router to spend SDVD
        IERC20(sdvd).approve(address(uniswapRouter), amountSDVD);
        // Add liquidity
        (,, uint256 liquidity) = uniswapRouter.addLiquidityETH{value : amountETH}(address(sdvd), amountSDVD, 0, 0, address(this), block.timestamp.add(30 minutes));

        // Approve self
        IERC20(stakedToken).approve(address(this), liquidity);
        // Stake LP token for sender
        _stake(address(this), msg.sender, liquidity);

        emit ClaimedAndStaked(msg.sender, liquidity);
    }

    /* ========== Internal ========== */

    /// @notice Stake ETH
    /// @param value Value in ETH
    function _stakeETH(uint256 value) internal {
        // If in LGE
        if (isLGEActive) {
            // SDVD-ETH pair address
            uint256 pairSDVDBalance = IERC20(sdvd).balanceOf(stakedToken);

            if (pairSDVDBalance == 0) {
                require(msg.value <= LGE_INITIAL_DEPOSIT_CAP, 'Initial deposit cap reached');
            }

            uint256 pairETHBalance = IERC20(weth).balanceOf(stakedToken);
            uint256 amountETH = msg.value;

            // If SDVD balance = 0 then set initial price
            uint256 amountSDVD = pairSDVDBalance == 0 ? amountETH.mul(LGE_INITIAL_PRICE_MULTIPLIER) : amountETH.mul(pairSDVDBalance).div(pairETHBalance);

            uint256 excessETH = 0;
            // If amount token to be minted pass the hard cap
            if (pairSDVDBalance.add(amountSDVD) > LGE_HARD_CAP) {
                // Get excess token
                uint256 excessToken = pairSDVDBalance.add(amountSDVD).sub(LGE_HARD_CAP);
                // Reduce it
                amountSDVD = amountSDVD.sub(excessToken);
                // Get excess ether
                excessETH = excessToken.mul(pairETHBalance).div(pairSDVDBalance);
                // Reduce amount ETH to be put on uniswap liquidity
                amountETH = amountETH.sub(excessETH);
            }

            // Mint LGE SDVD
            ISDvd(sdvd).mint(address(this), amountSDVD);

            // Add liquidity in uniswap and send the LP token to this contract
            IERC20(sdvd).approve(address(uniswapRouter), amountSDVD);
            (,, uint256 liquidity) = uniswapRouter.addLiquidityETH{value : amountETH}(address(sdvd), amountSDVD, 0, 0, address(this), block.timestamp.add(30 minutes));

            // Recheck the SDVD in pair address
            pairSDVDBalance = IERC20(sdvd).balanceOf(stakedToken);
            // Set LGE active state
            isLGEActive = pairSDVDBalance < LGE_HARD_CAP;

            // Approve self
            IERC20(stakedToken).approve(address(this), liquidity);
            // Stake LP token for sender
            _stake(address(this), msg.sender, liquidity);

            // If there is excess ETH
            if (excessETH > 0) {
                _stakeETH(excessETH);
            }
        } else {
            // Split ETH sent
            uint256 amountETH = value.div(2);

            // Swap path
            address[] memory path = new address[](2);
            path[0] = weth;
            path[1] = address(sdvd);

            // Swap ETH to SDVD using uniswap
            // Param: uint amountOutMin, address[] calldata path, address to, uint deadline
            uint256[] memory amounts = uniswapRouter.swapExactETHForTokens{value : amountETH}(
                0,
                path,
                address(this),
                block.timestamp.add(30 minutes)
            );
            // Get SDVD amount
            uint256 amountSDVDReceived = amounts[1];

            // Get pair address balance
            uint256 pairSDVDBalance = IERC20(sdvd).balanceOf(stakedToken);
            uint256 pairETHBalance = IERC20(weth).balanceOf(stakedToken);

            // Get available ETH
            amountETH = value.sub(amountETH);
            // Calculate amount of SDVD needed to add liquidity
            uint256 amountSDVD = amountETH.mul(pairSDVDBalance).div(pairETHBalance);

            // If required SDVD amount to add liquidity is bigger than what we have
            // Then we need to reduce ETH amount
            if (amountSDVD > amountSDVDReceived) {
                // Set SDVD amount
                amountSDVD = amountSDVDReceived;
                // Get amount ETH needed to add liquidity
                uint256 amountETHRequired = amountSDVD.mul(pairETHBalance).div(pairSDVDBalance);
                // Send dust back to sender
                if (amountETH > amountETHRequired) {
                    msg.sender.transfer(amountETH.sub(amountETHRequired));
                }
                // Set ETH amount
                amountETH = amountETHRequired;
            }
            // Else if we have too much SDVD
            else if (amountSDVDReceived > amountSDVD) {
                // Send dust
                IERC20(sdvd).transfer(msg.sender, amountSDVDReceived.sub(amountSDVD));
            }

            // Approve uniswap router to spend SDVD
            IERC20(sdvd).approve(address(uniswapRouter), amountSDVD);
            // Add liquidity
            (,, uint256 liquidity) = uniswapRouter.addLiquidityETH{value : amountETH}(address(sdvd), amountSDVD, 0, 0, address(this), block.timestamp.add(30 minutes));
            // Sync total token supply
            ISDvd(sdvd).syncPairTokenTotalSupply();

            // Approve self
            IERC20(stakedToken).approve(address(this), liquidity);
            // Stake LP token for sender
            _stake(address(this), msg.sender, liquidity);
        }

        emit StakedETH(msg.sender, msg.value);
    }

}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
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));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        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 safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "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");
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

{
  "compilationTarget": {
    "contracts/SDvdEthPool.sol": "SDvdEthPool"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}