// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/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.
 */
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() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(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");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: @openzeppelin/contracts/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

/**
 * @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].
 */
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 making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be _NOT_ENTERED
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

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

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

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == _ENTERED;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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 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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from, address to, uint256 amount) external returns (bool);
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @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 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;
    }
}

// File: @openzeppelin/contracts/utils/math/SafeMath.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/math/SafeMath.sol)

pragma solidity ^0.8.0;

// 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 generally not needed starting with Solidity 0.8, since 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 subtraction 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;
        }
    }
}

// File: contracts/Staking.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.14;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

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

contract Staking is Ownable, ReentrancyGuard {
    using SafeMath for uint256;

    address DEAD = 0x000000000000000000000000000000000000dEaD;

    // Whether a limit is set for users
    bool public hasUserLimit;

    // Whether it is initialized
    bool public isInitialized;

    // Accrued token per share
    uint256 public accTokenPerShare;

    // The block number when CAKE mining ends.
    uint256 public bonusEndBlock;

    // The block number when CAKE mining starts.
    uint256 public startBlock;

    // The block number of the last pool update
    uint256 public lastRewardBlock;

    // The pool limit (0 if none)
    uint256 public poolLimitPerUser;

    // CAKE tokens created per block.
    uint256 public rewardPerBlock;

    // The precision factor
    uint256 public PRECISION_FACTOR;

    // The staked token
    IERC20 public stakedToken;

    uint256 public totalStakedTokens;

    uint256 public lockTime;

    uint256 public depositFee;

    uint256 public earlyPenalty;

    IERC20 public rewardToken;

    // Info of each user that stakes tokens (stakedToken)
    mapping(address => UserInfo) public userInfo;

    struct UserInfo {
        uint256 amount; // How many staked tokens the user has provided
        uint256 rewardDebt; // Reward debt
        uint256 stakedTime;
    }

    event AdminTokenRecovery(address tokenRecovered, uint256 amount);
    event Deposit(address indexed user, uint256 amount);
    event EmergencyWithdraw(address indexed user, uint256 amount);
    event NewStartAndEndBlocks(uint256 startBlock, uint256 endBlock);
    event NewRewardPerBlock(uint256 rewardPerBlock);
    event NewPoolLimit(uint256 poolLimitPerUser);
    event RewardsStop(uint256 blockNumber);
    event Withdraw(address indexed user, uint256 amount);

    // constructor() public {
    //     SMART_CHEF_FACTORY = msg.sender;
    // }

    /*
     * @notice Initialize the contract
     * @param _stakedToken: staked token address
     * @param _rewardToken: reward token address
     * @param _rewardPerBlock: reward per block (in rewardToken)
     * @param _startBlock: start block
     * @param _bonusEndBlock: end block
     * @param _poolLimitPerUser: pool limit per user in stakedToken (if any, else 0)
     * @param _admin: admin address with ownership
     */

    constructor(
        IERC20 _stakedToken,
        uint256 _totalRewards,
        uint256 _startTime,
        uint256 _endTime,
        uint256 _poolLimitPerUser,
        uint256 _lockTime,
        uint256 _decimal
    ) {
        stakedToken = _stakedToken;
        rewardToken = _stakedToken;

        uint256 _startBlock = block.number +
            ((_startTime - block.timestamp) * 3);
        uint256 _bonusEndBlock = block.number +
            ((_endTime - block.timestamp) * 3);
        startBlock = _startBlock;
        bonusEndBlock = _bonusEndBlock;

        rewardPerBlock = _totalRewards / (bonusEndBlock - startBlock);

        PRECISION_FACTOR = uint256(10 ** (uint256(30).sub(_decimal)));

        // Set the lastRewardBlock as the startBlock
        lastRewardBlock = startBlock;

        lockTime = _lockTime;

        earlyPenalty = 15;

        _updatePool();

        // Transfer ownership to the admin address who becomes owner of the contract
        // transferOwnership(_admin);
    }

    /*
     * @notice Deposit staked tokens and collect reward tokens (if any)
     * @param _amount: amount to withdraw (in rewardToken)
     */
    function deposit(uint256 _amount) external nonReentrant {
        UserInfo storage user = userInfo[msg.sender];

        if (hasUserLimit) {
            require(
                _amount.add(user.amount) <= poolLimitPerUser,
                "User amount exceeds limit"
            );
        }

        _updatePool();

        if (user.amount > 0) {
            uint256 pending = user
                .amount
                .mul(accTokenPerShare)
                .div(PRECISION_FACTOR)
                .sub(user.rewardDebt);
            if (pending > 0) {
                stakedToken.transfer(address(msg.sender), pending);
            }
        }

        if (_amount > 0) {
            user.amount = user.amount.add(_amount);
            uint256 _previousBalance = stakedToken.balanceOf(address(this));
            stakedToken.transferFrom(
                address(msg.sender),
                address(this),
                _amount
            );

            uint256 _currentBalance = stakedToken.balanceOf(address(this));

            require(
                (_currentBalance - _previousBalance) >= _amount,
                "We didn't get the required amount"
            );
        }

        user.rewardDebt = user.amount.mul(accTokenPerShare).div(
            PRECISION_FACTOR
        );

        user.stakedTime = block.timestamp;

        totalStakedTokens += _amount;

        emit Deposit(msg.sender, _amount);
    }

    /*
     * @notice Withdraw staked tokens and collect reward tokens
     * @param _amount: amount to withdraw (in rewardToken)
     */
    function withdraw(uint256 _amount) external nonReentrant {
        UserInfo storage user = userInfo[msg.sender];
        require(user.amount >= _amount, "Withdrawal amount is too high");

        require(
            user.stakedTime.add(lockTime) <= block.timestamp,
            "Tokens are not unlocked"
        );

        _updatePool();

        uint256 pending = user
            .amount
            .mul(accTokenPerShare)
            .div(PRECISION_FACTOR)
            .sub(user.rewardDebt);

        if (_amount > 0) {
            user.amount = user.amount.sub(_amount);
            stakedToken.transfer(address(msg.sender), _amount);
        }

        if (pending > 0) {
            stakedToken.transfer(address(msg.sender), pending);
        }

        user.rewardDebt = user.amount.mul(accTokenPerShare).div(
            PRECISION_FACTOR
        );

        totalStakedTokens -= _amount;
        emit Withdraw(msg.sender, _amount);
    }

    /*
     * @notice Withdraw staked tokens without caring about rewards rewards
     * @dev Needs to be for emergency.
     */
    function emergencyWithdraw() external nonReentrant {
        UserInfo storage user = userInfo[msg.sender];

        require(
            user.stakedTime.add(lockTime) >= block.timestamp,
            "Tokens are unlocked"
        );
        uint256 stakedAmount = user.amount;

        user.amount = 0;
        user.rewardDebt = 0;

        uint256 penaltyAmount = stakedAmount.mul(earlyPenalty).div(100);

        uint256 amountToTransfer = stakedAmount.sub(penaltyAmount);

        if (amountToTransfer > 0) {
            stakedToken.transfer(address(msg.sender), amountToTransfer);
        }
        if (penaltyAmount > 0) {
            stakedToken.transfer(DEAD, penaltyAmount);
        }

        totalStakedTokens -= user.amount;

        emit EmergencyWithdraw(msg.sender, user.amount);
    }

    function changeLockTime(uint256 _lockTime) external onlyOwner {
        lockTime = _lockTime;
    }

    function changePaneltyAmount(uint256 _percentage) external onlyOwner {
        require(
            _percentage <= 50,
            "Panelty Percentage can not be greater than 50%"
        );
        earlyPenalty = _percentage;
    }

    /*
     * @notice Stop rewards
     * @dev Only callable by owner
     */
    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);
    }

    /*
     * @notice Update reward per block
     * @dev Only callable by owner.
     * @param _rewardPerBlock: the reward per block
     */
    function updateRewardPerBlock(uint256 _rewardPerBlock) external onlyOwner {
        require(block.number < startBlock, "Pool has started");
        rewardPerBlock = _rewardPerBlock;
        emit NewRewardPerBlock(_rewardPerBlock);
    }

    /**
     * @notice It allows the admin to update start and end blocks
     * @dev This function is only callable by owner.
     * @param _startBlock: the new start block
     * @param _bonusEndBlock: the new end block
     */
    function updateStartAndEndBlocks(
        uint256 _startBlock,
        uint256 _bonusEndBlock
    ) external onlyOwner {
        require(block.number < startBlock, "Pool has started");
        require(
            _startBlock < _bonusEndBlock,
            "New startBlock must be lower than new endBlock"
        );
        require(
            block.number < _startBlock,
            "New startBlock must be higher than current block"
        );

        startBlock = _startBlock;
        bonusEndBlock = _bonusEndBlock;

        // Set the lastRewardBlock as the startBlock
        lastRewardBlock = startBlock;

        emit NewStartAndEndBlocks(_startBlock, _bonusEndBlock);
    }

    /*
     * @notice View function to see pending reward on frontend.
     * @param _user: user address
     * @return Pending reward for a given user
     */
    function pendingReward(address _user) external view returns (uint256) {
        UserInfo storage user = userInfo[_user];
        if (block.number > lastRewardBlock && totalStakedTokens != 0) {
            uint256 multiplier = _getMultiplier(lastRewardBlock, block.number);
            uint256 cakeReward = multiplier.mul(rewardPerBlock);
            uint256 adjustedTokenPerShare = accTokenPerShare.add(
                cakeReward.mul(PRECISION_FACTOR).div(totalStakedTokens)
            );
            return
                user
                    .amount
                    .mul(adjustedTokenPerShare)
                    .div(PRECISION_FACTOR)
                    .sub(user.rewardDebt);
        } else {
            return
                user.amount.mul(accTokenPerShare).div(PRECISION_FACTOR).sub(
                    user.rewardDebt
                );
        }
    }

    /*
     * @notice Update reward variables of the given pool to be up-to-date.
     */
    function _updatePool() internal {
        if (block.number <= lastRewardBlock) {
            return;
        }

        uint256 totalAmount = totalStakedTokens;

        if (totalAmount == 0) {
            totalAmount = 1;
        }

        uint256 multiplier = _getMultiplier(lastRewardBlock, block.number);
        uint256 cakeReward = multiplier.mul(rewardPerBlock);
        accTokenPerShare = accTokenPerShare.add(
            cakeReward.mul(PRECISION_FACTOR).div(totalAmount)
        );
        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 {}
}