Contract Address Details

// Sources flattened with hardhat v2.9.3 https://hardhat.org

// File @openzeppelin/contracts/utils/Context.sol@v4.5.0

// 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/access/Ownable.sol@v4.5.0

// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

pragma solidity ^0.8.0;

/**
 * @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 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 {
        _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@v4.5.0

// OpenZeppelin Contracts v4.4.1 (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() {
        // 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;
    }
}

// File @openzeppelin/contracts/token/ERC20/IERC20.sol@v4.5.0

// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)

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 `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);

    /**
     * @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);
}

// File @openzeppelin/contracts/utils/Address.sol@v4.5.0

// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @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
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 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);
            }
        }
    }
}

// File @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol@v4.5.0

// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

/**
 * @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");
        }
    }
}

// File @openzeppelin/contracts/utils/math/Math.sol@v4.5.0

// OpenZeppelin Contracts (last updated v4.5.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @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.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a / b + (a % b == 0 ? 0 : 1);
    }
}

// File @openzeppelin/contracts/utils/math/SafeMath.sol@v4.5.0

// OpenZeppelin Contracts v4.4.1 (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 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;
        }
    }
}

// File contracts/interfaces/ILiquidityMiningFund.sol

pragma solidity 0.8.4;

interface ILiquidityMiningFund {
    function transfer(address _address, uint256 _amount) external;
}

// File contracts/interfaces/IWETH.sol

pragma solidity 0.8.4;

interface IWETH is IERC20 {
    function deposit() external payable;

    function withdraw(uint256 wad) external;
}

// File contracts/farms/MilkyMultiFeeDistributor.sol

pragma solidity 0.8.4;

// Based on Geist's MultiFeeDistribution
contract MilkyMultiFeeDistributor is ReentrancyGuard, Ownable {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    /* ========== STATE VARIABLES ========== */

    struct Reward {
        uint256 periodFinish;
        uint256 rewardRate;
        uint256 lastUpdateTime;
        uint256 rewardPerTokenStored;
    }
    struct Balances {
        uint256 total;
        uint256 unlocked;
        uint256 locked;
        uint256 earned;
    }
    struct LockedBalance {
        uint256 amount;
        uint256 unlockTime;
    }
    struct RewardData {
        address token;
        uint256 amount;
    }

    IERC20 public stakingToken;
    ILiquidityMiningFund public stakingTokenFund;
    IWETH public weth;
    address[] public rewardTokens;
    mapping(address => Reward) public rewardData;

    // Duration that rewards are streamed over
    uint256 public constant rewardsDuration = 86400 * 7; // 1 week

    // Duration of lock/earned penalty period
    uint256 public constant lockDuration = rewardsDuration * 12; // 12 weeks

    // Addresses approved to call mint
    mapping(address => bool) public minters;
    address[] public mintersArray;

    // reward token -> distributor -> is approved to add rewards
    mapping(address => mapping(address => bool)) public rewardDistributors;

    // user -> reward token -> amount
    mapping(address => mapping(address => uint256)) public userRewardPerTokenPaid;
    mapping(address => mapping(address => uint256)) public rewards;

    uint256 public totalSupply;
    uint256 public lockedSupply;

    // Private mappings for balance data
    mapping(address => Balances) private balances;
    mapping(address => LockedBalance[]) private userLocks;
    mapping(address => LockedBalance[]) private userEarnings;

    /* ========== CONSTRUCTOR ========== */

    constructor(
        address _stakingToken,
        address _stakingTokenFund,
        address _weth
    ) Ownable() {
        stakingToken = IERC20(_stakingToken);
        stakingTokenFund = ILiquidityMiningFund(_stakingTokenFund);
        weth = IWETH(_weth);
        // First reward MUST be the staking token or things will break
        // related to the 50% penalty and distribution to locked balances
        rewardTokens.push(_stakingToken);
        rewardData[_stakingToken].lastUpdateTime = block.timestamp;
        rewardData[_stakingToken].periodFinish = block.timestamp;
    }

    /* ========== ADMIN CONFIGURATION ========== */

    // Add a new reward token to be distributed to stakers
    function addReward(address _rewardsToken, address _distributor) public onlyOwner {
        require(
            rewardData[_rewardsToken].lastUpdateTime == 0,
            "MultiFeeDistribution::addReward: Invalid"
        );
        rewardTokens.push(_rewardsToken);
        rewardData[_rewardsToken].lastUpdateTime = block.timestamp;
        rewardData[_rewardsToken].periodFinish = block.timestamp;
        rewardDistributors[_rewardsToken][_distributor] = true;
        emit RewardTokenAdded(_rewardsToken);
        emit RewardDistributorApproved(_rewardsToken, _distributor, true);
    }

    // Modify approval for an address to call notifyRewardAmount
    function approveRewardDistributor(
        address _rewardsToken,
        address _distributor,
        bool _approved
    ) external onlyOwner {
        require(
            rewardData[_rewardsToken].lastUpdateTime > 0,
            "MultiFeeDistribution::approveRewardDistributor: Invalid"
        );
        rewardDistributors[_rewardsToken][_distributor] = _approved;
        emit RewardDistributorApproved(_rewardsToken, _distributor, _approved);
    }

    /* ========== VIEWS ========== */

    function _rewardPerToken(address _rewardsToken, uint256 _supply)
        internal
        view
        returns (uint256)
    {
        if (_supply == 0) {
            return rewardData[_rewardsToken].rewardPerTokenStored;
        }
        return
            rewardData[_rewardsToken].rewardPerTokenStored.add(
                lastTimeRewardApplicable(_rewardsToken)
                    .sub(rewardData[_rewardsToken].lastUpdateTime)
                    .mul(rewardData[_rewardsToken].rewardRate)
                    .mul(1e18)
                    .div(_supply)
            );
    }

    function _earned(
        address _user,
        address _rewardsToken,
        uint256 _balance,
        uint256 supply
    ) internal view returns (uint256) {
        return
            _balance
                .mul(
                    _rewardPerToken(_rewardsToken, supply).sub(
                        userRewardPerTokenPaid[_user][_rewardsToken]
                    )
                )
                .div(1e18)
                .add(rewards[_user][_rewardsToken]);
    }

    function lastTimeRewardApplicable(address _rewardsToken) public view returns (uint256) {
        return Math.min(block.timestamp, rewardData[_rewardsToken].periodFinish);
    }

    function rewardPerToken(address _rewardsToken) external view returns (uint256) {
        uint256 supply = _rewardsToken == address(stakingToken) ? lockedSupply : totalSupply;
        return _rewardPerToken(_rewardsToken, supply);
    }

    function getRewardForDuration(address _rewardsToken) external view returns (uint256) {
        return rewardData[_rewardsToken].rewardRate.mul(rewardsDuration);
    }

    // Address and claimable amount of all reward tokens for the given account
    function claimableRewards(address account)
        external
        view
        returns (RewardData[] memory _rewards)
    {
        _rewards = new RewardData[](rewardTokens.length);
        for (uint256 i = 0; i < _rewards.length; i++) {
            // If i == 0 this is the stakingReward, distribution is based on locked balances
            uint256 balance = i == 0 ? balances[account].locked : balances[account].total;
            uint256 supply = i == 0 ? lockedSupply : totalSupply;
            _rewards[i].token = rewardTokens[i];
            _rewards[i].amount = _earned(account, _rewards[i].token, balance, supply);
        }
        return _rewards;
    }

    // Total balance of an account, including unlocked, locked and earned tokens
    function totalBalance(address user) external view returns (uint256 amount) {
        return balances[user].total;
    }

    // Total withdrawable balance for an account to which no penalty is applied
    function unlockedBalance(address user) external view returns (uint256 amount) {
        amount = balances[user].unlocked;
        LockedBalance[] storage earnings = userEarnings[msg.sender];
        for (uint256 i = 0; i < earnings.length; i++) {
            if (earnings[i].unlockTime > block.timestamp) {
                break;
            }
            amount = amount.add(earnings[i].amount);
        }
        return amount;
    }

    // Information on the "earned" balances of a user
    // Earned balances may be withdrawn immediately for a 50% penalty
    function earnedBalances(address user)
        external
        view
        returns (uint256 total, LockedBalance[] memory earningsData)
    {
        LockedBalance[] storage earnings = userEarnings[user];
        uint256 idx;
        for (uint256 i = 0; i < earnings.length; i++) {
            if (earnings[i].unlockTime > block.timestamp) {
                if (idx == 0) {
                    earningsData = new LockedBalance[](earnings.length - i);
                }
                earningsData[idx] = earnings[i];
                idx++;
                total = total.add(earnings[i].amount);
            }
        }
        return (total, earningsData);
    }

    // Information on a user's locked balances
    function lockedBalances(address user)
        external
        view
        returns (
            uint256 total,
            uint256 unlockable,
            uint256 locked,
            LockedBalance[] memory lockData
        )
    {
        LockedBalance[] storage locks = userLocks[user];
        uint256 idx;
        for (uint256 i = 0; i < locks.length; i++) {
            if (locks[i].unlockTime > block.timestamp) {
                if (idx == 0) {
                    lockData = new LockedBalance[](locks.length - i);
                }
                lockData[idx] = locks[i];
                idx++;
                locked = locked.add(locks[i].amount);
            } else {
                unlockable = unlockable.add(locks[i].amount);
            }
        }
        return (balances[user].locked, unlockable, locked, lockData);
    }

    // Final balance received and penalty balance paid by user upon calling exit
    function withdrawableBalance(address user)
        public
        view
        returns (uint256 amount, uint256 penaltyAmount)
    {
        Balances storage bal = balances[user];
        if (bal.earned > 0) {
            uint256 amountWithoutPenalty;
            uint256 length = userEarnings[user].length;
            for (uint256 i = 0; i < length; i++) {
                uint256 earnedAmount = userEarnings[user][i].amount;
                if (earnedAmount == 0) continue;
                if (userEarnings[user][i].unlockTime > block.timestamp) {
                    break;
                }
                amountWithoutPenalty = amountWithoutPenalty.add(earnedAmount);
            }

            penaltyAmount = bal.earned.sub(amountWithoutPenalty).div(2);
        }
        amount = bal.unlocked.add(bal.earned).sub(penaltyAmount);
        return (amount, penaltyAmount);
    }

    /* ========== MUTATIVE FUNCTIONS ========== */

    // Stake tokens to receive rewards
    // Locked tokens cannot be withdrawn for lockDuration and are eligible to receive stakingReward rewards
    function stake(uint256 amount, bool lock) external nonReentrant updateReward(msg.sender) {
        require(amount > 0, "MultiFeeDistribution::stake: Cannot stake 0");
        totalSupply = totalSupply.add(amount);
        Balances storage bal = balances[msg.sender];
        bal.total = bal.total.add(amount);
        if (lock) {
            lockedSupply = lockedSupply.add(amount);
            bal.locked = bal.locked.add(amount);
            uint256 unlockTime = block.timestamp.div(rewardsDuration).mul(rewardsDuration).add(
                lockDuration
            );
            uint256 idx = userLocks[msg.sender].length;
            if (idx == 0 || userLocks[msg.sender][idx - 1].unlockTime < unlockTime) {
                userLocks[msg.sender].push(LockedBalance({amount: amount, unlockTime: unlockTime}));
            } else {
                userLocks[msg.sender][idx - 1].amount = userLocks[msg.sender][idx - 1].amount.add(
                    amount
                );
            }
        } else {
            bal.unlocked = bal.unlocked.add(amount);
        }
        stakingToken.safeTransferFrom(msg.sender, address(this), amount);
        emit Staked(msg.sender, amount);
    }

    // Mint new tokens
    // Minted tokens receive rewards normally but incur a 50% penalty when
    // withdrawn before lockDuration has passed.
    function mint(address user, uint256 amount) external updateReward(user) {
        require(minters[msg.sender], "MultiFeeDistribution::mint: Only minters allowed");
        totalSupply = totalSupply.add(amount);
        Balances storage bal = balances[user];
        bal.total = bal.total.add(amount);
        bal.earned = bal.earned.add(amount);
        uint256 unlockTime = block.timestamp.div(rewardsDuration).mul(rewardsDuration).add(
            lockDuration
        );
        LockedBalance[] storage earnings = userEarnings[user];
        uint256 idx = earnings.length;

        if (idx == 0 || earnings[idx - 1].unlockTime < unlockTime) {
            earnings.push(LockedBalance({amount: amount, unlockTime: unlockTime}));
        } else {
            earnings[idx - 1].amount = earnings[idx - 1].amount.add(amount);
        }
        stakingTokenFund.transfer(address(this), amount);
        emit Staked(user, amount);
    }

    // Withdraw staked tokens
    // First withdraws unlocked tokens, then earned tokens. Withdrawing earned tokens
    // incurs a 50% penalty which is distributed based on locked balances.
    function withdraw(uint256 amount) public nonReentrant updateReward(msg.sender) {
        require(amount > 0, "MultiFeeDistribution::withdraw: Cannot withdraw 0");
        Balances storage bal = balances[msg.sender];
        uint256 penaltyAmount;

        if (amount <= bal.unlocked) {
            bal.unlocked = bal.unlocked.sub(amount);
        } else {
            uint256 remaining = amount.sub(bal.unlocked);
            require(
                bal.earned >= remaining,
                "MultiFeeDistribution::withdraw: Insufficient unlocked balance"
            );
            bal.unlocked = 0;
            bal.earned = bal.earned.sub(remaining);
            for (uint256 i = 0; ; i++) {
                uint256 earnedAmount = userEarnings[msg.sender][i].amount;
                if (earnedAmount == 0) continue;
                if (
                    penaltyAmount == 0 && userEarnings[msg.sender][i].unlockTime > block.timestamp
                ) {
                    penaltyAmount = remaining;
                    require(
                        bal.earned >= remaining,
                        "MultiFeeDistribution::withdraw: Insufficient balance after penalty"
                    );
                    bal.earned = bal.earned.sub(remaining);
                    if (bal.earned == 0) {
                        delete userEarnings[msg.sender];
                        break;
                    }
                    remaining = remaining.mul(2);
                }
                if (remaining <= earnedAmount) {
                    userEarnings[msg.sender][i].amount = earnedAmount.sub(remaining);
                    break;
                } else {
                    delete userEarnings[msg.sender][i];
                    remaining = remaining.sub(earnedAmount);
                }
            }
        }

        uint256 adjustedAmount = amount.add(penaltyAmount);
        bal.total = bal.total.sub(adjustedAmount);
        totalSupply = totalSupply.sub(adjustedAmount);
        stakingToken.safeTransfer(msg.sender, amount);
        if (penaltyAmount > 0) {
            _notifyReward(address(stakingToken), penaltyAmount);
        }
        emit Withdrawn(msg.sender, amount);
    }

    // Claim all pending staking rewards
    function getReward() public nonReentrant updateReward(msg.sender) {
        for (uint256 i; i < rewardTokens.length; i++) {
            address _rewardToken = rewardTokens[i];
            uint256 reward = rewards[msg.sender][_rewardToken];
            if (reward > 0) {
                rewards[msg.sender][_rewardToken] = 0;
                if (_rewardToken == address(weth)) {
                    weth.withdraw(reward);
                    Address.sendValue(payable(msg.sender), reward);
                } else {
                    IERC20(_rewardToken).safeTransfer(msg.sender, reward);
                }
                emit RewardPaid(msg.sender, _rewardToken, reward);
            }
        }
    }

    // Withdraw full unlocked balance and claim pending rewards
    function emergencyWithdraw() external updateReward(msg.sender) {
        (uint256 amount, uint256 penaltyAmount) = withdrawableBalance(msg.sender);
        delete userEarnings[msg.sender];
        Balances storage bal = balances[msg.sender];
        bal.total = bal.total.sub(bal.unlocked).sub(bal.earned);
        bal.unlocked = 0;
        bal.earned = 0;

        totalSupply = totalSupply.sub(amount.add(penaltyAmount));
        stakingToken.safeTransfer(msg.sender, amount);
        if (penaltyAmount > 0) {
            _notifyReward(address(stakingToken), penaltyAmount);
        }
        getReward();
    }

    // Withdraw all currently locked tokens where the unlock time has passed
    function withdrawExpiredLocks() external {
        LockedBalance[] storage locks = userLocks[msg.sender];
        Balances storage bal = balances[msg.sender];
        uint256 amount;
        uint256 length = locks.length;
        if (locks[length - 1].unlockTime <= block.timestamp) {
            amount = bal.locked;
            delete userLocks[msg.sender];
        } else {
            for (uint256 i = 0; i < length; i++) {
                if (locks[i].unlockTime > block.timestamp) break;
                amount = amount.add(locks[i].amount);
                delete locks[i];
            }
        }
        bal.locked = bal.locked.sub(amount);
        bal.total = bal.total.sub(amount);
        totalSupply = totalSupply.sub(amount);
        lockedSupply = lockedSupply.sub(amount);
        stakingToken.safeTransfer(msg.sender, amount);
    }

    /* ========== RESTRICTED FUNCTIONS ========== */

    function _notifyReward(address _rewardsToken, uint256 reward) internal {
        if (block.timestamp >= rewardData[_rewardsToken].periodFinish) {
            rewardData[_rewardsToken].rewardRate = reward.div(rewardsDuration);
        } else {
            uint256 remaining = rewardData[_rewardsToken].periodFinish.sub(block.timestamp);
            uint256 leftover = remaining.mul(rewardData[_rewardsToken].rewardRate);
            rewardData[_rewardsToken].rewardRate = reward.add(leftover).div(rewardsDuration);
        }

        rewardData[_rewardsToken].lastUpdateTime = block.timestamp;
        rewardData[_rewardsToken].periodFinish = block.timestamp.add(rewardsDuration);
    }

    function notifyRewardAmount(address _rewardsToken, uint256 reward)
        external
        updateReward(address(0))
    {
        require(
            rewardDistributors[_rewardsToken][msg.sender],
            "MultiFeeDistribution::notifyRewardAmount: Only reward distributors allowed"
        );
        require(reward > 0, "MultiFeeDistribution::notifyRewardAmount: No reward");
        // handle the transfer of reward tokens via `transferFrom` to reduce the number
        // of transactions required and ensure correctness of the reward amount
        IERC20(_rewardsToken).safeTransferFrom(msg.sender, address(this), reward);
        _notifyReward(_rewardsToken, reward);
        emit RewardAdded(reward);
    }

    // Added to support recovering LP Rewards from other systems such as BAL to be distributed to holders
    function recoverERC20(address tokenAddress, uint256 tokenAmount) external onlyOwner {
        require(
            tokenAddress != address(stakingToken),
            "MultiFeeDistribution::recoverERC20: Cannot withdraw staking token"
        );
        require(
            rewardData[tokenAddress].lastUpdateTime == 0,
            "MultiFeeDistribution::recoverERC20: Cannot withdraw reward token"
        );
        IERC20(tokenAddress).safeTransfer(owner(), tokenAmount);
        emit Recovered(tokenAddress, tokenAmount);
    }

    function addMinter(address _newMinter) external onlyOwner {
        require(_newMinter != address(0), "MultiFeeDistribution::addMinter: Invalid address");
        require(!minters[_newMinter], "MultiFeeDistribution::addMinter: Minter existed");
        minters[_newMinter] = true;
        mintersArray.push(_newMinter);
        emit MinterAdded(_newMinter);
    }

    function removeMinter(address _minter) external onlyOwner {
        require(minters[_minter], "MultiFeeDistribution::addMinter: Minter not found");
        delete minters[_minter];
        for (uint256 i = 0; i < mintersArray.length; i++) {
            if (mintersArray[i] == _minter) {
                mintersArray[i] = address(0);
                // This will leave a null in the array and keep the indices the same
                break;
            }
        }
        emit MinterRemoved(_minter);
    }

    /* ========== MODIFIERS ========== */

    modifier updateReward(address account) {
        address token = address(stakingToken);
        uint256 balance;
        uint256 supply = lockedSupply;
        rewardData[token].rewardPerTokenStored = _rewardPerToken(token, supply);
        rewardData[token].lastUpdateTime = lastTimeRewardApplicable(token);
        if (account != address(0)) {
            // Special case, use the locked balances and supply for stakingReward rewards
            rewards[account][token] = _earned(account, token, balances[account].locked, supply);
            userRewardPerTokenPaid[account][token] = rewardData[token].rewardPerTokenStored;
            balance = balances[account].total;
        }

        supply = totalSupply;
        for (uint256 i = 1; i < rewardTokens.length; i++) {
            token = rewardTokens[i];
            rewardData[token].rewardPerTokenStored = _rewardPerToken(token, supply);
            rewardData[token].lastUpdateTime = lastTimeRewardApplicable(token);
            if (account != address(0)) {
                rewards[account][token] = _earned(account, token, balance, supply);
                userRewardPerTokenPaid[account][token] = rewardData[token].rewardPerTokenStored;
            }
        }
        _;
    }

    receive() external payable {}

    /* ========== EVENTS ========== */

    event RewardAdded(uint256 reward);
    event RewardTokenAdded(address indexed rewardTokenAddress);
    event RewardDistributorApproved(
        address indexed rewardAddress,
        address indexed distributor,
        bool approved
    );
    event Staked(address indexed user, uint256 amount);
    event Withdrawn(address indexed user, uint256 amount);
    event RewardPaid(address indexed user, address indexed rewardsToken, uint256 reward);
    event Recovered(address token, uint256 amount);
    event MinterAdded(address indexed minter);
    event MinterRemoved(address indexed minter);
}