// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/**
 * @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);
}


/**
 * @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 on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        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");

        (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");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        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

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}


/**
 * @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 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) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is no longer needed starting with Solidity 0.8. The compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // 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 (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @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) {
        return a + b;
    }

    /**
     * @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 a - b;
    }

    /**
     * @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) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting 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 a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting 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) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * 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) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}



interface IUniRouter01 {
    function factory() external pure returns (address);

    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
        external
        returns (
            uint256 amountA,
            uint256 amountB,
            uint256 liquidity
        );

    function addLiquidityETH(
        address token,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
        external
        payable
        returns (
            uint256 amountToken,
            uint256 amountETH,
            uint256 liquidity
        );

    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountA, uint256 amountB);

    function removeLiquidityETH(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountToken, uint256 amountETH);

    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountA, uint256 amountB);

    function removeLiquidityETHWithPermit(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountToken, uint256 amountETH);

    function swapExactTokensForTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapTokensForExactTokens(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapExactETHForTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);

    function swapTokensForExactETH(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapExactTokensForETH(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);

    function swapETHForExactTokens(
        uint256 amountOut,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);

    function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) external pure returns (uint256 amountB);

    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) external pure returns (uint256 amountOut);

    function getAmountIn(
        uint256 amountOut,
        uint256 reserveIn,
        uint256 reserveOut
    ) external pure returns (uint256 amountIn);

    function getAmountsOut(uint256 amountIn, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);

    function getAmountsIn(uint256 amountOut, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);
}


interface IWETH {
    function deposit() external payable;
    function transfer(address to, uint value) external returns (bool);
    function withdraw(uint) external;
}

interface IUniRouter02 is IUniRouter01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountETH);

    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;

    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable;

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;
}

/**
 * @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].
 */
abstract 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() {
        _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;
    }
}

/**
 * @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.
 */
abstract 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() {
        _setOwner(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual 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 {
        _setOwner(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");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

/**
 * @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 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'
        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) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _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
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

interface IToken {
     /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the token decimals.
     */
    function decimals() external view returns (uint8);

    /**
     * @dev Returns the token symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the token name.
     */
    function name() external view returns (string memory);
}

contract DHPStaking is Ownable, ReentrancyGuard {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    // The address of the smart chef factory
    address public POOL_FACTORY;

    // Whether it is initialized
    bool public isInitialized;
    uint256 public duration = 365; // 365 days

    // Whether a limit is set for users
    bool public hasUserLimit;
    // The pool limit (0 if none)
    uint256 public poolLimitPerUser;


    // The block number when staking starts.
    uint256 public startBlock;
    // The block number when staking ends.
    uint256 public bonusEndBlock;


    address public walletA;

    // The precision factor
    uint256 public PRECISION_FACTOR;


    // The staked token
    IERC20 public stakingToken;
    // The earned token
    IERC20 public earnedToken;


    uint256 public totalStaked;

    uint256 private totalEarned;

    struct Lockup {
        uint8 stakeType;
        uint256 duration;
        uint256 depositFee;
        uint256 withdrawFee;
        uint256 rate;
        uint256 accTokenPerShare;
        uint256 lastRewardBlock;
        uint256 totalStaked;
    }

    struct UserInfo {
        uint256 amount; // How many staked tokens the user has provided
        uint256 locked;
        uint256 available;
    }

    struct Stake {
        uint8   stakeType;
        uint256 amount;     // amount to stake
        uint256 duration;   // the lockup duration of the stake
        uint256 end;        // when does the staking period end
        uint256 rewardDebt; // Reward debt
    }
    uint256 constant MAX_STAKES = 256;

    Lockup[] public lockups;
    mapping(address => Stake[]) public userStakes;
    mapping(address => UserInfo) public userStaked;

    event Deposit(address indexed user, uint256 stakeType, uint256 amount);
    event Withdraw(address indexed user, uint256 stakeType, uint256 amount);
    event EmergencyWithdraw(address indexed user, uint256 amount);
    event AdminTokenRecovered(address tokenRecovered, uint256 amount);

    event NewStartAndEndBlocks(uint256 startBlock, uint256 endBlock);
    event LockupUpdated(uint8 _type, uint256 _duration, uint256 _fee0, uint256 _fee1, uint256 _rate);
    event NewPoolLimit(uint256 poolLimitPerUser);
    event RewardsStop(uint256 blockNumber);


    event WalletAUpadted(address _walletA);
    event BuybackAddressUpadted(address _addr);
    event DurationUpdated(uint256 _duration);


    constructor() {
        POOL_FACTORY = msg.sender;
    }

    /*
     * @notice Initialize the contract
     * @param _stakingToken: staked token address
     * @param _earnedToken: earned token address
     */
    function initialize(
        IERC20 _stakingToken,
        IERC20 _earnedToken
    ) external {
        require(!isInitialized, "Already initialized");
        require(msg.sender == POOL_FACTORY, "Not factory");

        // Make this contract initialized
        isInitialized = true;

        stakingToken = _stakingToken;
        earnedToken = _earnedToken;

        walletA = address(0x3A8c5f8bFb00B2525FF7f620B7653e65A26e0d5e);

        uint256 decimalsRewardToken = uint256(IToken(address(earnedToken)).decimals());
        require(decimalsRewardToken < 30, "Must be inferior to 30");
        PRECISION_FACTOR = uint256(10**(uint256(40).sub(decimalsRewardToken)));


        lockups.push(Lockup(0, 7, 0, 300, 10000000000000, 0, 0, 0)); // 1% liquidity
        lockups.push(Lockup(1, 15, 0, 300, 10000000000000, 0, 0, 0)); // 1.5% liquidity
        lockups.push(Lockup(2, 30, 0, 300, 10000000000000, 0, 0, 0)); // 2% liquidity
        lockups.push(Lockup(3, 90, 0, 300, 10000000000000, 0, 0, 0)); // 2.5% liquidity

    }

    /*
     * @notice Deposit staked tokens and collect reward tokens (if any)
     * @param _amount: amount to withdraw (in earnedToken)
     */
    function deposit(uint256 _amount, uint8 _stakeType) external nonReentrant {
        require(_amount > 0, "Amount should be greator than 0");
        require(_stakeType < lockups.length, "Invalid stake type");

        _updatePool(_stakeType);

        UserInfo storage user = userStaked[msg.sender];
        Stake[] storage stakes = userStakes[msg.sender];
        Lockup storage lockup = lockups[_stakeType];

        uint256 pending = 0;
        uint256 pendingCompound = 0;
        uint256 compounded = 0;
        for(uint256 j = 0; j < stakes.length; j++) {
            Stake storage stake = stakes[j];
            if(stake.stakeType != _stakeType) continue;
            if(stake.amount == 0) continue;


            uint256 _pending = stake.amount.mul(lockup.accTokenPerShare).div(PRECISION_FACTOR).sub(stake.rewardDebt);
            if(stake.end > block.timestamp) {
                pendingCompound = pendingCompound.add(_pending);

                compounded = compounded.add(_pending);
                stake.amount = stake.amount.add(_pending);
            } else {
                pending = pending.add(_pending);
            }
            stake.rewardDebt = stake.amount.mul(lockup.accTokenPerShare).div(PRECISION_FACTOR);
        }

        if (pending > 0) {
            require(availableRewardTokens() >= pending, "Insufficient reward tokens");
            earnedToken.safeTransfer(address(msg.sender), pending);
            
            if(totalEarned > pending) {
                totalEarned = totalEarned.sub(pending);
            } else {
                totalEarned = 0;
            }
        }

        if (pendingCompound > 0) {
            require(availableRewardTokens() >= pendingCompound, "Insufficient reward tokens");
            
            if(totalEarned > pendingCompound) {
                totalEarned = totalEarned.sub(pendingCompound);
            } else {
                totalEarned = 0;
            }
        }


        uint256 beforeAmount = stakingToken.balanceOf(address(this));
        stakingToken.safeTransferFrom(
            address(msg.sender),
            address(this),
            _amount
        );
        uint256 afterAmount = stakingToken.balanceOf(address(this));        
        uint256 realAmount = afterAmount.sub(beforeAmount);

        if (hasUserLimit) {
            require(
                realAmount.add(user.amount) <= poolLimitPerUser,
                "User amount above limit"
            );
        }
        if (lockup.depositFee > 0) {
            uint256 fee = realAmount.mul(lockup.depositFee).div(10000);
            if (fee > 0) {
                stakingToken.safeTransfer(walletA, fee);
                realAmount = realAmount.sub(fee);
            }
        }
        
        _addStake(_stakeType, msg.sender, lockup.duration, realAmount);

        user.amount = user.amount.add(realAmount).add(compounded);
        lockup.totalStaked = lockup.totalStaked.add(realAmount).add(compounded);
        totalStaked = totalStaked.add(realAmount).add(compounded);

        emit Deposit(msg.sender, _stakeType, realAmount.add(compounded));
    }

    function _addStake(uint8 _stakeType, address _account, uint256 _duration, uint256 _amount) internal {
        Stake[] storage stakes = userStakes[_account];

        uint256 end = block.timestamp.add(_duration.mul(1 days));
        uint256 i = stakes.length;
        require(i < MAX_STAKES, "Max stakes");

        stakes.push(); // grow the array
        // find the spot where we can insert the current stake
        // this should make an increasing list sorted by end
        while (i != 0 && stakes[i - 1].end > end) {
            // shift it back one
            stakes[i] = stakes[i - 1];
            i -= 1;
        }
        
        Lockup storage lockup = lockups[_stakeType];

        // insert the stake
        Stake storage newStake = stakes[i];
        newStake.stakeType = _stakeType;
        newStake.duration = _duration;
        newStake.end = end;
        newStake.amount = _amount;
        newStake.rewardDebt = newStake.amount.mul(lockup.accTokenPerShare).div(PRECISION_FACTOR);
    }

    /*
     * @notice Withdraw staked tokens and collect reward tokens
     * @param _amount: amount to withdraw (in earnedToken)
     */
    function withdraw(uint256 _amount, uint8 _stakeType) external nonReentrant {
        require(_amount > 0, "Amount should be greator than 0");
        require(_stakeType < lockups.length, "Invalid stake type");

        _updatePool(_stakeType);

        UserInfo storage user = userStaked[msg.sender];
        Stake[] storage stakes = userStakes[msg.sender];
        Lockup storage lockup = lockups[_stakeType];
        
        uint256 pending = 0;
        uint256 pendingCompound = 0;
        uint256 compounded = 0;
        uint256 remained = _amount;
        for(uint256 j = 0; j < stakes.length; j++) {
            Stake storage stake = stakes[j];
            if(stake.stakeType != _stakeType) continue;
            if(stake.amount == 0) continue;
            if(remained == 0) break;

            uint256 _pending = stake.amount.mul(lockup.accTokenPerShare).div(PRECISION_FACTOR).sub(stake.rewardDebt);

            if(stake.end > block.timestamp) {
                pendingCompound = pendingCompound.add(_pending);

                
                compounded = compounded.add(_pending);
                stake.amount = stake.amount.add(_pending);
            } else {
                pending = pending.add(_pending);
                if(stake.amount > remained) {
                    stake.amount = stake.amount.sub(remained);
                    remained = 0;
                } else {
                    remained = remained.sub(stake.amount);
                    stake.amount = 0;
                }
            }
            stake.rewardDebt = stake.amount.mul(lockup.accTokenPerShare).div(PRECISION_FACTOR);
        }

        if (pending > 0) {
            require(availableRewardTokens() >= pending, "Insufficient reward tokens");
            earnedToken.safeTransfer(address(msg.sender), pending);
            
            if(totalEarned > pending) {
                totalEarned = totalEarned.sub(pending);
            } else {
                totalEarned = 0;
            }
        }

        if (pendingCompound > 0) {
            require(availableRewardTokens() >= pendingCompound, "Insufficient reward tokens");
            
            if(totalEarned > pendingCompound) {
                totalEarned = totalEarned.sub(pendingCompound);
            } else {
                totalEarned = 0;
            }
            
            emit Deposit(msg.sender, _stakeType, compounded);
        }


        uint256 realAmount = _amount.sub(remained);
        user.amount = user.amount.sub(realAmount).add(pendingCompound);
        lockup.totalStaked = lockup.totalStaked.sub(realAmount).add(pendingCompound);
        totalStaked = totalStaked.sub(realAmount).add(pendingCompound);

        if(realAmount > 0) {
            if (lockup.withdrawFee > 0) {
                uint256 fee = realAmount.mul(lockup.withdrawFee).div(10000);
                stakingToken.safeTransfer(walletA, fee);
                realAmount = realAmount.sub(fee);
            }

            stakingToken.safeTransfer(address(msg.sender), realAmount);
        }

        emit Withdraw(msg.sender, _stakeType, realAmount);
    }

    function claimReward(uint8 _stakeType) external nonReentrant {
        if(_stakeType >= lockups.length) return;
        if(startBlock == 0) return;

        _updatePool(_stakeType);

        Stake[] storage stakes = userStakes[msg.sender];
        Lockup storage lockup = lockups[_stakeType];

        uint256 pending = 0;
        for(uint256 j = 0; j < stakes.length; j++) {
            Stake storage stake = stakes[j];
            if(stake.stakeType != _stakeType) continue;
            if(stake.amount == 0) continue;

            uint256 _pending = stake.amount.mul(lockup.accTokenPerShare).div(PRECISION_FACTOR).sub(stake.rewardDebt);

                     pending = pending.add(_pending);
            
            stake.rewardDebt = stake.amount.mul(lockup.accTokenPerShare).div(PRECISION_FACTOR);
        }

        if (pending > 0) {
            require(availableRewardTokens() >= pending, "Insufficient reward tokens");
            earnedToken.safeTransfer(address(msg.sender), pending);
            
            if(totalEarned > pending) {
                totalEarned = totalEarned.sub(pending);
            } else {
                totalEarned = 0;
            }
        }

    }


    function compoundReward(uint8 _stakeType) external nonReentrant {
        if(_stakeType >= lockups.length) return;
        if(startBlock == 0) return;

        _updatePool(_stakeType);

        UserInfo storage user = userStaked[msg.sender];
        Stake[] storage stakes = userStakes[msg.sender];
        Lockup storage lockup = lockups[_stakeType];

        uint256 pending = 0;
        uint256 pendingCompound = 0;
        for(uint256 j = 0; j < stakes.length; j++) {
            Stake storage stake = stakes[j];
            if(stake.stakeType != _stakeType) continue;
            if(stake.amount == 0) continue;

            uint256 _pending = stake.amount.mul(lockup.accTokenPerShare).div(PRECISION_FACTOR).sub(stake.rewardDebt);
            pending = pending.add(_pending);

            pendingCompound = pendingCompound.add(_pending);

            stake.amount = stake.amount.add(_pending);
            stake.rewardDebt = stake.amount.mul(lockup.accTokenPerShare).div(PRECISION_FACTOR);
            
        }

        if (pending > 0) {
            require(availableRewardTokens() >= pending, "Insufficient reward tokens");
            
            if(totalEarned > pending) {
                totalEarned = totalEarned.sub(pending);
            } else {
                totalEarned = 0;
            }

            user.amount = user.amount.add(pendingCompound);
            lockup.totalStaked = lockup.totalStaked.add(pendingCompound);
            totalStaked = totalStaked.add(pendingCompound);

            emit Deposit(msg.sender, _stakeType, pendingCompound);
        }
    }

    /*
     * @notice Withdraw staked tokens without caring about rewards
     * @dev Needs to be for emergency.
     */
    function emergencyWithdraw(uint8 _stakeType) external nonReentrant {
        if(_stakeType >= lockups.length) return;

        UserInfo storage user = userStaked[msg.sender];
        Stake[] storage stakes = userStakes[msg.sender];
        Lockup storage lockup = lockups[_stakeType];

        uint256 amountToTransfer = 0;
        for(uint256 j = 0; j < stakes.length; j++) {
            Stake storage stake = stakes[j];
            if(stake.stakeType != _stakeType) continue;
            if(stake.amount == 0) continue;

            amountToTransfer = amountToTransfer.add(stake.amount);

            stake.amount = 0;
            stake.rewardDebt = 0;
        }

        if (amountToTransfer > 0) {
            stakingToken.safeTransfer(address(msg.sender), amountToTransfer);

            user.amount = user.amount.sub(amountToTransfer);
            lockup.totalStaked = lockup.totalStaked.sub(amountToTransfer);
            totalStaked = totalStaked.sub(amountToTransfer);
        }

        emit EmergencyWithdraw(msg.sender, amountToTransfer);
    }

    function rewardPerBlock(uint8 _stakeType) public view returns (uint256) {
        if(_stakeType >= lockups.length) return 0;

        return lockups[_stakeType].rate;
    }

    /**
     * @notice Available amount of reward token
     */
    function availableRewardTokens() public view returns (uint256) {

        uint256 _amount = earnedToken.balanceOf(address(this));
        if (address(earnedToken) == address(stakingToken)) {
            if (_amount < totalStaked) return 0;
            return _amount.sub(totalStaked);
        }

        return _amount;
    }


    function userInfo(uint8 _stakeType, address _account) public view returns (uint256 amount, uint256 available, uint256 locked) {
        Stake[] storage stakes = userStakes[_account];
        
        for(uint256 i = 0; i < stakes.length; i++) {
            Stake storage stake = stakes[i];

            if(stake.stakeType != _stakeType) continue;
            if(stake.amount == 0) continue;
            
            amount = amount.add(stake.amount);
            if(block.timestamp > stake.end) {
                available = available.add(stake.amount);
            } else {
                locked = locked.add(stake.amount);
            }
        }
    }

    /*
     * @notice View function to see pending reward on frontend.
     * @param _user: user address
     * @return Pending reward for a given user
     */
    function pendingReward(address _account, uint8 _stakeType) external view returns (uint256) {
        if(_stakeType >= lockups.length) return 0;
        if(startBlock == 0) return 0;

        Stake[] storage stakes = userStakes[_account];
        Lockup storage lockup = lockups[_stakeType];

        if(lockup.totalStaked == 0) return 0;
        
        uint256 adjustedTokenPerShare = lockup.accTokenPerShare;
        if (block.number > lockup.lastRewardBlock && lockup.totalStaked != 0) {
            uint256 multiplier = _getMultiplier(lockup.lastRewardBlock, block.number);
            uint256 reward = multiplier.mul(lockup.rate);
            adjustedTokenPerShare =
                lockup.accTokenPerShare.add(
                    reward.mul(PRECISION_FACTOR).div(lockup.totalStaked)
                );
        }

        uint256 pending = 0;
        for(uint256 i = 0; i < stakes.length; i++) {
            Stake storage stake = stakes[i];
            if(stake.stakeType != _stakeType) continue;
            if(stake.amount == 0) continue;

            pending = pending.add(
                stake.amount.mul(adjustedTokenPerShare).div(PRECISION_FACTOR).sub(stake.rewardDebt)
            );
        }
        return pending;
    }


    /************************
    ** Admin Methods
    *************************/
    function harvest() external onlyOwner {        
        _updatePool(0);

        uint256 _amount = stakingToken.balanceOf(address(this));
        _amount = _amount.sub(totalStaked);

    }

    /*
     * @notice Deposit reward token
     * @dev Only call by owner. Needs to be for deposit of reward token when reflection token is same with reward token.
     */
    function depositRewards(uint _amount) external nonReentrant {
        require(_amount > 0);

        uint256 beforeAmt = earnedToken.balanceOf(address(this));
        earnedToken.safeTransferFrom(msg.sender, address(this), _amount);
        uint256 afterAmt = earnedToken.balanceOf(address(this));

        totalEarned = totalEarned.add(afterAmt).sub(beforeAmt);
    }

    /*
     * @notice Withdraw reward token
     * @dev Only callable by owner. Needs to be for emergency.
     */
    function emergencyRewardWithdraw(uint256 _amount) external onlyOwner {
        require( block.number > bonusEndBlock, "Pool is running");

        earnedToken.safeTransfer(address(msg.sender), _amount);
        
        if (totalEarned > 0) {
            if (_amount > totalEarned) {
                totalEarned = 0;
            } else {
                totalEarned = totalEarned.sub(_amount);
            }
        }
    }

    /**
     * @notice It allows the admin to recover wrong tokens sent to the contract
     * @param _tokenAddress: the address of the token to withdraw
     * @param _tokenAmount: the number of tokens to withdraw
     * @dev This function is only callable by admin.
     */
    function recoverWrongTokens(address _tokenAddress, uint256 _tokenAmount)
        external
        onlyOwner
    {
        require(
            _tokenAddress != address(earnedToken),
            "Cannot be reward token"
        );

        if(_tokenAddress == address(stakingToken)) {
            uint256 tokenBal = stakingToken.balanceOf(address(this));
            require(_tokenAmount <= tokenBal.sub(totalStaked), "Insufficient balance");
        }

        if(_tokenAddress == address(0x0)) {
            payable(msg.sender).transfer(_tokenAmount);
        } else {
            IERC20(_tokenAddress).safeTransfer(address(msg.sender), _tokenAmount);
        }

        emit AdminTokenRecovered(_tokenAddress, _tokenAmount);
    }

    function startReward() external onlyOwner {
        require(startBlock == 0, "Pool was already started");

        startBlock = block.number.add(100);
        bonusEndBlock = startBlock.add(duration * 28800);
        for(uint256 i = 0; i < lockups.length; i++) {
            lockups[i].lastRewardBlock = startBlock;
        }
        
        emit NewStartAndEndBlocks(startBlock, bonusEndBlock);
    }

    function stopReward() external onlyOwner {
        bonusEndBlock = block.number;
    }

    /*
     * @notice Update pool limit per user
     * @dev Only callable by owner.
     * @param _hasUserLimit: whether the limit remains forced
     * @param _poolLimitPerUser: new pool limit per user
     */
    function updatePoolLimitPerUser( bool _hasUserLimit, uint256 _poolLimitPerUser) external onlyOwner {
        require(hasUserLimit, "Must be set");
        if (_hasUserLimit) {
            require(
                _poolLimitPerUser > poolLimitPerUser,
                "New limit must be higher"
            );
            poolLimitPerUser = _poolLimitPerUser;
        } else {
            hasUserLimit = _hasUserLimit;
            poolLimitPerUser = 0;
        }
        emit NewPoolLimit(poolLimitPerUser);
    }

    function updateLockup(uint8 _stakeType, uint256 _duration, uint256 _depositFee, uint256 _withdrawFee, uint256 _rate) external onlyOwner {
        // require(block.number < startBlock, "Pool was already started");
        require(_stakeType < lockups.length, "Lockup Not found");
        require(_depositFee < 2000, "Invalid deposit fee");
        require(_withdrawFee < 2000, "Invalid withdraw fee");

        Lockup storage _lockup = lockups[_stakeType];
        _lockup.duration = _duration;
        _lockup.depositFee = _depositFee;
        _lockup.withdrawFee = _withdrawFee;
        _lockup.rate = _rate;
        
        emit LockupUpdated(_stakeType, _duration, _depositFee, _withdrawFee, _rate);
    }

    function addLockup(uint256 _duration, uint256 _depositFee, uint256 _withdrawFee, uint256 _rate) external onlyOwner {
        require(_depositFee < 2000, "Invalid deposit fee");
        require(_withdrawFee < 2000, "Invalid withdraw fee");
        
        lockups.push();
        
        Lockup storage _lockup = lockups[lockups.length - 1];
        _lockup.duration = _duration;
        _lockup.depositFee = _depositFee;
        _lockup.withdrawFee = _withdrawFee;
        _lockup.rate = _rate;
        _lockup.lastRewardBlock = block.number;

        emit LockupUpdated(uint8(lockups.length - 1), _duration, _depositFee, _withdrawFee, _rate);
    }

    function updateWalletA(address _walletA) external onlyOwner {
        require(_walletA != address(0x0) || _walletA != walletA, "Invalid address");

        walletA = _walletA;
        emit WalletAUpadted(_walletA);
    }

    function setDuration(uint256 _duration) external onlyOwner {
        require(startBlock == 0, "Pool was already started");
        require(_duration >= 30, "lower limit reached");

        duration = _duration;
        emit DurationUpdated(_duration);
    }



    /************************
    ** Internal Methods
    *************************/
    /*
     * @notice Update reward variables of the given pool to be up-to-date.
     */
    function _updatePool(uint8 _stakeType) internal {

        Lockup storage lockup = lockups[_stakeType];
        if (block.number <= lockup.lastRewardBlock) return;

        if (lockup.totalStaked == 0) {
            lockup.lastRewardBlock = block.number;
            return;
        }

        uint256 multiplier = _getMultiplier(lockup.lastRewardBlock, block.number);
        uint256 _reward = multiplier.mul(lockup.rate);
        lockup.accTokenPerShare = lockup.accTokenPerShare.add(
            _reward.mul(PRECISION_FACTOR).div(lockup.totalStaked)
        );
        lockup.lastRewardBlock = block.number;
    }

    /*
     * @notice Return reward multiplier over the given _from to _to block.
     * @param _from: block to start
     * @param _to: block to finish
     */
    function _getMultiplier(uint256 _from, uint256 _to)
        internal
        view
        returns (uint256)
    {
        if (_to <= bonusEndBlock) {
            return _to.sub(_from);
        } else if (_from >= bonusEndBlock) {
            return 0;
        } else {
            return bonusEndBlock.sub(_from);
        }
    }


    receive() external payable {}
}