// SPDX-License-Identifier: MIT
pragma solidity 0.8.7;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library MathUpgradeable {
	/**
	 * @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);
	}
}

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20Upgradeable {
	/**
	 * @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 Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20MetadataUpgradeable is IERC20Upgradeable {
	/**
	 * @dev Returns the name of the token.
	 */
	function name() external view returns (string memory);

	/**
	 * @dev Returns the symbol of the token.
	 */
	function symbol() external view returns (string memory);

	/**
	 * @dev Returns the decimals places of the token.
	 */
	function decimals() external view returns (uint8);
}

/**
 * @dev Collection of functions related to the address type
 */
library AddressUpgradeable {
	/**
	 * @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 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 This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 *
 * [CAUTION]
 * ====
 * Avoid leaving a contract uninitialized.
 *
 * An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
 * contract, which may impact the proxy. To initialize the implementation contract, you can either invoke the
 * initializer manually, or you can include a constructor to automatically mark it as initialized when it is deployed:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * /// @custom:oz-upgrades-unsafe-allow constructor
 * constructor() initializer {}
 * ```
 * ====
 */
abstract contract Initializable {
	/**
	 * @dev Indicates that the contract has been initialized.
	 */
	bool private _initialized;

	/**
	 * @dev Indicates that the contract is in the process of being initialized.
	 */
	bool private _initializing;

	/**
	 * @dev Modifier to protect an initializer function from being invoked twice.
	 */
	modifier initializer() {
		// If the contract is initializing we ignore whether _initialized is set in order to support multiple
		// inheritance patterns, but we only do this in the context of a constructor, because in other contexts the
		// contract may have been reentered.
		require(_initializing ? _isConstructor() : !_initialized, "Initializable: contract is already initialized");

		bool isTopLevelCall = !_initializing;
		if (isTopLevelCall) {
			_initializing = true;
			_initialized = true;
		}

		_;

		if (isTopLevelCall) {
			_initializing = false;
		}
	}

	/**
	 * @dev Modifier to protect an initialization function so that it can only be invoked by functions with the
	 * {initializer} modifier, directly or indirectly.
	 */
	modifier onlyInitializing() {
		require(_initializing, "Initializable: contract is not initializing");
		_;
	}

	function _isConstructor() private view returns (bool) {
		return !AddressUpgradeable.isContract(address(this));
	}
}

/**
 * @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 ContextUpgradeable is Initializable {
	function __Context_init() internal onlyInitializing {
		__Context_init_unchained();
	}

	function __Context_init_unchained() internal onlyInitializing {}

	function _msgSender() internal view virtual returns (address) {
		return msg.sender;
	}

	function _msgData() internal view virtual returns (bytes calldata) {
		return msg.data;
	}

	uint256[50] private __gap;
}

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20Upgradeable is Initializable, ContextUpgradeable, IERC20Upgradeable, IERC20MetadataUpgradeable {
	mapping(address => uint256) private _balances;

	mapping(address => mapping(address => uint256)) private _allowances;

	uint256 private _totalSupply;

	string private _name;
	string private _symbol;

	/**
	 * @dev Sets the values for {name} and {symbol}.
	 *
	 * The default value of {decimals} is 18. To select a different value for
	 * {decimals} you should overload it.
	 *
	 * All two of these values are immutable: they can only be set once during
	 * construction.
	 */
	function __ERC20_init(string memory name_, string memory symbol_) internal onlyInitializing {
		__Context_init_unchained();
		__ERC20_init_unchained(name_, symbol_);
	}

	function __ERC20_init_unchained(string memory name_, string memory symbol_) internal onlyInitializing {
		_name = name_;
		_symbol = symbol_;
	}

	/**
	 * @dev Returns the name of the token.
	 */
	function name() public view virtual override returns (string memory) {
		return _name;
	}

	/**
	 * @dev Returns the symbol of the token, usually a shorter version of the
	 * name.
	 */
	function symbol() public view virtual override returns (string memory) {
		return _symbol;
	}

	/**
	 * @dev Returns the number of decimals used to get its user representation.
	 * For example, if `decimals` equals `2`, a balance of `505` tokens should
	 * be displayed to a user as `5.05` (`505 / 10 ** 2`).
	 *
	 * Tokens usually opt for a value of 18, imitating the relationship between
	 * Ether and Wei. This is the value {ERC20} uses, unless this function is
	 * overridden;
	 *
	 * NOTE: This information is only used for _display_ purposes: it in
	 * no way affects any of the arithmetic of the contract, including
	 * {IERC20-balanceOf} and {IERC20-transfer}.
	 */
	function decimals() public view virtual override returns (uint8) {
		return 18;
	}

	/**
	 * @dev See {IERC20-totalSupply}.
	 */
	function totalSupply() public view virtual override returns (uint256) {
		return _totalSupply;
	}

	/**
	 * @dev See {IERC20-balanceOf}.
	 */
	function balanceOf(address account) public view virtual override returns (uint256) {
		return _balances[account];
	}

	/**
	 * @dev See {IERC20-transfer}.
	 *
	 * Requirements:
	 *
	 * - `recipient` cannot be the zero address.
	 * - the caller must have a balance of at least `amount`.
	 */
	function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
		_transfer(_msgSender(), recipient, amount);
		return true;
	}

	/**
	 * @dev See {IERC20-allowance}.
	 */
	function allowance(address owner, address spender) public view virtual override returns (uint256) {
		return _allowances[owner][spender];
	}

	/**
	 * @dev See {IERC20-approve}.
	 *
	 * Requirements:
	 *
	 * - `spender` cannot be the zero address.
	 */
	function approve(address spender, uint256 amount) public virtual override returns (bool) {
		_approve(_msgSender(), spender, amount);
		return true;
	}

	/**
	 * @dev See {IERC20-transferFrom}.
	 *
	 * Emits an {Approval} event indicating the updated allowance. This is not
	 * required by the EIP. See the note at the beginning of {ERC20}.
	 *
	 * Requirements:
	 *
	 * - `sender` and `recipient` cannot be the zero address.
	 * - `sender` must have a balance of at least `amount`.
	 * - the caller must have allowance for ``sender``'s tokens of at least
	 * `amount`.
	 */
	function transferFrom(
		address sender,
		address recipient,
		uint256 amount
	) public virtual override returns (bool) {
		_transfer(sender, recipient, amount);

		uint256 currentAllowance = _allowances[sender][_msgSender()];
		require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
		unchecked {
			_approve(sender, _msgSender(), currentAllowance - amount);
		}

		return true;
	}

	/**
	 * @dev Atomically increases the allowance granted to `spender` by the caller.
	 *
	 * This is an alternative to {approve} that can be used as a mitigation for
	 * problems described in {IERC20-approve}.
	 *
	 * Emits an {Approval} event indicating the updated allowance.
	 *
	 * Requirements:
	 *
	 * - `spender` cannot be the zero address.
	 */
	function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
		_approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
		return true;
	}

	/**
	 * @dev Atomically decreases the allowance granted to `spender` by the caller.
	 *
	 * This is an alternative to {approve} that can be used as a mitigation for
	 * problems described in {IERC20-approve}.
	 *
	 * Emits an {Approval} event indicating the updated allowance.
	 *
	 * Requirements:
	 *
	 * - `spender` cannot be the zero address.
	 * - `spender` must have allowance for the caller of at least
	 * `subtractedValue`.
	 */
	function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
		uint256 currentAllowance = _allowances[_msgSender()][spender];
		require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
		unchecked {
			_approve(_msgSender(), spender, currentAllowance - subtractedValue);
		}

		return true;
	}

	/**
	 * @dev Moves `amount` of tokens from `sender` to `recipient`.
	 *
	 * This internal function is equivalent to {transfer}, and can be used to
	 * e.g. implement automatic token fees, slashing mechanisms, etc.
	 *
	 * Emits a {Transfer} event.
	 *
	 * Requirements:
	 *
	 * - `sender` cannot be the zero address.
	 * - `recipient` cannot be the zero address.
	 * - `sender` must have a balance of at least `amount`.
	 */
	function _transfer(
		address sender,
		address recipient,
		uint256 amount
	) internal virtual {
		require(sender != address(0), "ERC20: transfer from the zero address");
		require(recipient != address(0), "ERC20: transfer to the zero address");

		_beforeTokenTransfer(sender, recipient, amount);

		uint256 senderBalance = _balances[sender];
		require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
		unchecked {
			_balances[sender] = senderBalance - amount;
		}
		_balances[recipient] += amount;

		emit Transfer(sender, recipient, amount);

		_afterTokenTransfer(sender, recipient, amount);
	}

	/** @dev Creates `amount` tokens and assigns them to `account`, increasing
	 * the total supply.
	 *
	 * Emits a {Transfer} event with `from` set to the zero address.
	 *
	 * Requirements:
	 *
	 * - `account` cannot be the zero address.
	 */
	function _mint(address account, uint256 amount) internal virtual {
		require(account != address(0), "ERC20: mint to the zero address");

		_beforeTokenTransfer(address(0), account, amount);

		_totalSupply += amount;
		_balances[account] += amount;
		emit Transfer(address(0), account, amount);

		_afterTokenTransfer(address(0), account, amount);
	}

	/**
	 * @dev Destroys `amount` tokens from `account`, reducing the
	 * total supply.
	 *
	 * Emits a {Transfer} event with `to` set to the zero address.
	 *
	 * Requirements:
	 *
	 * - `account` cannot be the zero address.
	 * - `account` must have at least `amount` tokens.
	 */
	function _burn(address account, uint256 amount) internal virtual {
		require(account != address(0), "ERC20: burn from the zero address");

		_beforeTokenTransfer(account, address(0), amount);

		uint256 accountBalance = _balances[account];
		require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
		unchecked {
			_balances[account] = accountBalance - amount;
		}
		_totalSupply -= amount;

		emit Transfer(account, address(0), amount);

		_afterTokenTransfer(account, address(0), amount);
	}

	/**
	 * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
	 *
	 * This internal function is equivalent to `approve`, and can be used to
	 * e.g. set automatic allowances for certain subsystems, etc.
	 *
	 * Emits an {Approval} event.
	 *
	 * Requirements:
	 *
	 * - `owner` cannot be the zero address.
	 * - `spender` cannot be the zero address.
	 */
	function _approve(
		address owner,
		address spender,
		uint256 amount
	) internal virtual {
		require(owner != address(0), "ERC20: approve from the zero address");
		require(spender != address(0), "ERC20: approve to the zero address");

		_allowances[owner][spender] = amount;
		emit Approval(owner, spender, amount);
	}

	/**
	 * @dev Hook that is called before any transfer of tokens. This includes
	 * minting and burning.
	 *
	 * Calling conditions:
	 *
	 * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
	 * will be transferred to `to`.
	 * - when `from` is zero, `amount` tokens will be minted for `to`.
	 * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
	 * - `from` and `to` are never both zero.
	 *
	 * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
	 */
	function _beforeTokenTransfer(
		address from,
		address to,
		uint256 amount
	) internal virtual {}

	/**
	 * @dev Hook that is called after any transfer of tokens. This includes
	 * minting and burning.
	 *
	 * Calling conditions:
	 *
	 * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
	 * has been transferred to `to`.
	 * - when `from` is zero, `amount` tokens have been minted for `to`.
	 * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
	 * - `from` and `to` are never both zero.
	 *
	 * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
	 */
	function _afterTokenTransfer(
		address from,
		address to,
		uint256 amount
	) internal virtual {}

	uint256[45] private __gap;
}

/**
 * @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 SafeERC20Upgradeable {
	using AddressUpgradeable for address;

	function safeTransfer(
		IERC20Upgradeable token,
		address to,
		uint256 value
	) internal {
		_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
	}

	function safeTransferFrom(
		IERC20Upgradeable 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(
		IERC20Upgradeable 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(
		IERC20Upgradeable 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(
		IERC20Upgradeable 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(IERC20Upgradeable 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");
		}
	}
}

/**
 * @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 ReentrancyGuardUpgradeable is Initializable {
	// 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;

	function __ReentrancyGuard_init() internal onlyInitializing {
		__ReentrancyGuard_init_unchained();
	}

	function __ReentrancyGuard_init_unchained() internal onlyInitializing {
		_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;
	}
	uint256[49] private __gap;
}

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract PausableUpgradeable is Initializable, ContextUpgradeable {
	/**
	 * @dev Emitted when the pause is triggered by `account`.
	 */
	event Paused(address account);

	/**
	 * @dev Emitted when the pause is lifted by `account`.
	 */
	event Unpaused(address account);

	bool private _paused;

	/**
	 * @dev Initializes the contract in unpaused state.
	 */
	function __Pausable_init() internal onlyInitializing {
		__Context_init_unchained();
		__Pausable_init_unchained();
	}

	function __Pausable_init_unchained() internal onlyInitializing {
		_paused = false;
	}

	/**
	 * @dev Returns true if the contract is paused, and false otherwise.
	 */
	function paused() public view virtual returns (bool) {
		return _paused;
	}

	/**
	 * @dev Modifier to make a function callable only when the contract is not paused.
	 *
	 * Requirements:
	 *
	 * - The contract must not be paused.
	 */
	modifier whenNotPaused() {
		require(!paused(), "Pausable: paused");
		_;
	}

	/**
	 * @dev Modifier to make a function callable only when the contract is paused.
	 *
	 * Requirements:
	 *
	 * - The contract must be paused.
	 */
	modifier whenPaused() {
		require(paused(), "Pausable: not paused");
		_;
	}

	/**
	 * @dev Triggers stopped state.
	 *
	 * Requirements:
	 *
	 * - The contract must not be paused.
	 */
	function _pause() internal virtual whenNotPaused {
		_paused = true;
		emit Paused(_msgSender());
	}

	/**
	 * @dev Returns to normal state.
	 *
	 * Requirements:
	 *
	 * - The contract must be paused.
	 */
	function _unpause() internal virtual whenPaused {
		_paused = false;
		emit Unpaused(_msgSender());
	}

	uint256[49] private __gap;
}

contract GaugeMultiRewards is ReentrancyGuardUpgradeable, PausableUpgradeable, ERC20Upgradeable {
	using SafeERC20Upgradeable for ERC20Upgradeable;

	/* ========== STATE VARIABLES ========== */

	struct Reward {
		address rewardsDistributor;
		uint256 rewardsDuration;
		uint256 periodFinish;
		uint256 rewardRate;
		uint256 lastUpdateTime;
		uint256 rewardPerTokenStored;
	}

	ERC20Upgradeable public stakingToken;
	address public vault;

	mapping(address => Reward) public rewardData;

	address public governance;
	address[] public rewardTokens;

	// user -> reward token -> amount
	mapping(address => mapping(address => uint256)) public userRewardPerTokenPaid;
	mapping(address => mapping(address => uint256)) public rewards;

	uint256 private _totalStake;
	uint256 public derivedSupply;

	mapping(address => uint256) private _stakes;
	mapping(address => uint256) public derivedBalances;

	/* ========== CONSTRUCTOR ========== */

	function init(
		address _stakingToken,
		address _vault,
		address _governance,
		string memory _name,
		string memory _symbol
	) public initializer {
		__ERC20_init(_name, _symbol);
		governance = _governance;
		stakingToken = ERC20Upgradeable(_stakingToken);
		vault = _vault;
	}

	function addReward(
		address _rewardsToken,
		address _rewardsDistributor,
		uint256 _rewardsDuration
	) public onlyGovernance {
		require(rewardData[_rewardsToken].rewardsDuration == 0);
		rewardTokens.push(_rewardsToken);
		rewardData[_rewardsToken].rewardsDistributor = _rewardsDistributor;
		rewardData[_rewardsToken].rewardsDuration = _rewardsDuration;
	}

	/* ========== VIEWS ========== */

	function totalStaked() external view returns (uint256) {
		return _totalStake;
	}

	function stakeOf(address account) external view returns (uint256) {
		return _stakes[account];
	}

	function lastTimeRewardApplicable(address _rewardsToken) public view returns (uint256) {
		return MathUpgradeable.min(block.timestamp, rewardData[_rewardsToken].periodFinish);
	}

	function rewardPerToken(address _rewardsToken) public view returns (uint256) {
		if (_totalStake == 0) {
			return rewardData[_rewardsToken].rewardPerTokenStored;
		}
		return
			rewardData[_rewardsToken].rewardPerTokenStored +
			(((lastTimeRewardApplicable(_rewardsToken) - rewardData[_rewardsToken].lastUpdateTime) *
				rewardData[_rewardsToken].rewardRate *
				(10**stakingToken.decimals())) / _totalStake); // from 1e18
	}

	function earned(address _account, address _rewardsToken) public view returns (uint256) {
		uint256 userBalance = _stakes[_account];

		return
			(userBalance * (rewardPerToken(_rewardsToken) - userRewardPerTokenPaid[_account][_rewardsToken])) /
			(10**stakingToken.decimals()) +
			rewards[_account][_rewardsToken];
	}

	function getRewardForDuration(address _rewardsToken) external view returns (uint256) {
		return rewardData[_rewardsToken].rewardRate * rewardData[_rewardsToken].rewardsDuration;
	}

	/* ========== MUTATIVE FUNCTIONS ========== */

	function setRewardsDistributor(address _rewardsToken, address _rewardsDistributor) external onlyGovernance {
		rewardData[_rewardsToken].rewardsDistributor = _rewardsDistributor;
	}

	function _stake(uint256 amount, address account) internal nonReentrant whenNotPaused updateReward(account) {
		require(amount > 0, "Cannot stake 0");
		_totalStake = _totalStake + amount;
		_stakes[account] = _stakes[account] + amount;
		stakingToken.safeTransferFrom(msg.sender, address(this), amount);
		emit Staked(account, amount);
	}

	function _withdraw(uint256 amount, address account) internal nonReentrant updateReward(account) {
		require(amount > 0, "Cannot withdraw 0");
		_totalStake = _totalStake - amount;
		_stakes[account] = _stakes[account] - amount;
		stakingToken.safeTransfer(msg.sender, amount);
		emit Withdrawn(account, amount);
	}

	function stakeFor(address account, uint256 amount) external onlyVault {
		_stake(amount, account);
	}

	function withdrawFor(address account, uint256 amount) external onlyVault {
		_withdraw(amount, account);
	}

	function getRewardFor(address account) public nonReentrant updateReward(account) {
		for (uint256 i; i < rewardTokens.length; i++) {
			address _rewardsToken = rewardTokens[i];
			uint256 reward = rewards[account][_rewardsToken];
			if (reward > 0) {
				rewards[account][_rewardsToken] = 0;
				ERC20Upgradeable(_rewardsToken).safeTransfer(account, reward);
				emit RewardPaid(account, _rewardsToken, reward);
			}
		}
	}

	/* ========== RESTRICTED FUNCTIONS ========== */

	function setGovernance(address _governance) public onlyGovernance {
		governance = _governance;
	}

	function notifyRewardAmount(address _rewardsToken, uint256 reward) external updateReward(address(0)) {
		require(rewardData[_rewardsToken].rewardsDistributor == msg.sender);
		// handle the transfer of reward tokens via `transferFrom` to reduce the number
		// of transactions required and ensure correctness of the reward amount
		ERC20Upgradeable(_rewardsToken).safeTransferFrom(msg.sender, address(this), reward);

		if (block.timestamp >= rewardData[_rewardsToken].periodFinish) {
			rewardData[_rewardsToken].rewardRate = reward / rewardData[_rewardsToken].rewardsDuration;
		} else {
			uint256 remaining = rewardData[_rewardsToken].periodFinish - block.timestamp;
			uint256 leftover = remaining * rewardData[_rewardsToken].rewardRate;
			rewardData[_rewardsToken].rewardRate = (reward + leftover) / rewardData[_rewardsToken].rewardsDuration;
		}

		rewardData[_rewardsToken].lastUpdateTime = block.timestamp;
		rewardData[_rewardsToken].periodFinish = block.timestamp + rewardData[_rewardsToken].rewardsDuration;
		emit RewardAdded(reward);
	}

	function recoverERC20(
		address tokenAddress,
		uint256 tokenAmount,
		address destination
	) external onlyGovernance {
		require(tokenAddress != address(stakingToken), "Cannot withdraw staking token");
		require(rewardData[tokenAddress].lastUpdateTime == 0, "Cannot withdraw reward token");
		ERC20Upgradeable(tokenAddress).safeTransfer(destination, tokenAmount);
		emit Recovered(tokenAddress, tokenAmount);
	}

	function setRewardsDuration(address _rewardsToken, uint256 _rewardsDuration) external {
		require(block.timestamp > rewardData[_rewardsToken].periodFinish, "Reward period still active");
		require(rewardData[_rewardsToken].rewardsDistributor == msg.sender);
		require(_rewardsDuration > 0, "Reward duration must be non-zero");
		rewardData[_rewardsToken].rewardsDuration = _rewardsDuration;
		emit RewardsDurationUpdated(_rewardsToken, rewardData[_rewardsToken].rewardsDuration);
	}

	function mintFor(address _recipient, uint256 _amount) external onlyVault {
		_mint(_recipient, _amount);
	}

	function burnFrom(address _from, uint256 _amount) external onlyVault {
		_burn(_from, _amount);
	}

	function decimals() public view override returns (uint8) {
		return stakingToken.decimals();
	}

	/* ========== MODIFIERS ========== */

	modifier updateReward(address account) {
		for (uint256 i; i < rewardTokens.length; i++) {
			address token = rewardTokens[i];
			rewardData[token].rewardPerTokenStored = rewardPerToken(token);
			rewardData[token].lastUpdateTime = lastTimeRewardApplicable(token);
			if (account != address(0)) {
				rewards[account][token] = earned(account, token);
				userRewardPerTokenPaid[account][token] = rewardData[token].rewardPerTokenStored;
			}
		}
		_;
	}

	modifier onlyGovernance() {
		require(msg.sender == governance, "!gov");
		_;
	}

	modifier onlyVault() {
		require(msg.sender == vault, "!vault");
		_;
	}

	/* ========== EVENTS ========== */

	event RewardAdded(uint256 reward);
	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 RewardsDurationUpdated(address token, uint256 newDuration);
	event Recovered(address token, uint256 amount);
}