Cryo Explorer Ethereum Mainnet

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract AutomationBase {
  error OnlySimulatedBackend();

  /**
   * @notice method that allows it to be simulated via eth_call by checking that
   * the sender is the zero address.
   */
  function preventExecution() internal view {
    if (tx.origin != address(0)) {
      revert OnlySimulatedBackend();
    }
  }

  /**
   * @notice modifier that allows it to be simulated via eth_call by checking
   * that the sender is the zero address.
   */
  modifier cannotExecute() {
    preventExecution();
    _;
  }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "./AutomationBase.sol";
import "./interfaces/AutomationCompatibleInterface.sol";

abstract contract AutomationCompatible is AutomationBase, AutomationCompatibleInterface {}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface AutomationCompatibleInterface {
  /**
   * @notice method that is simulated by the keepers to see if any work actually
   * needs to be performed. This method does does not actually need to be
   * executable, and since it is only ever simulated it can consume lots of gas.
   * @dev To ensure that it is never called, you may want to add the
   * cannotExecute modifier from KeeperBase to your implementation of this
   * method.
   * @param checkData specified in the upkeep registration so it is always the
   * same for a registered upkeep. This can easily be broken down into specific
   * arguments using `abi.decode`, so multiple upkeeps can be registered on the
   * same contract and easily differentiated by the contract.
   * @return upkeepNeeded boolean to indicate whether the keeper should call
   * performUpkeep or not.
   * @return performData bytes that the keeper should call performUpkeep with, if
   * upkeep is needed. If you would like to encode data to decode later, try
   * `abi.encode`.
   */
  function checkUpkeep(bytes calldata checkData) external returns (bool upkeepNeeded, bytes memory performData);

  /**
   * @notice method that is actually executed by the keepers, via the registry.
   * The data returned by the checkUpkeep simulation will be passed into
   * this method to actually be executed.
   * @dev The input to this method should not be trusted, and the caller of the
   * method should not even be restricted to any single registry. Anyone should
   * be able call it, and the input should be validated, there is no guarantee
   * that the data passed in is the performData returned from checkUpkeep. This
   * could happen due to malicious keepers, racing keepers, or simply a state
   * change while the performUpkeep transaction is waiting for confirmation.
   * Always validate the data passed in.
   * @param performData is the data which was passed back from the checkData
   * simulation. If it is encoded, it can easily be decoded into other types by
   * calling `abi.decode`. This data should not be trusted, and should be
   * validated against the contract's current state.
   */
  function performUpkeep(bytes calldata performData) external;
}

// SPDX-License-Identifier: MIT
/**
 * @notice This is a deprecated interface. Please use AutomationCompatible directly.
 */
pragma solidity ^0.8.0;
import {AutomationCompatible as KeeperCompatible} from "./AutomationCompatible.sol";
import {AutomationBase as KeeperBase} from "./AutomationBase.sol";
import {AutomationCompatibleInterface as KeeperCompatibleInterface} from "./interfaces/AutomationCompatibleInterface.sol";

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

pragma solidity ^0.8.0;

import "./IAccessControl.sol";
import "../utils/Context.sol";
import "../utils/Strings.sol";
import "../utils/introspection/ERC165.sol";

/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms. This is a lightweight version that doesn't allow enumerating role
 * members except through off-chain means by accessing the contract event logs. Some
 * applications may benefit from on-chain enumerability, for those cases see
 * {AccessControlEnumerable}.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```solidity
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```solidity
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it. We recommend using {AccessControlDefaultAdminRules}
 * to enforce additional security measures for this role.
 */
abstract contract AccessControl is Context, IAccessControl, ERC165 {
    struct RoleData {
        mapping(address => bool) members;
        bytes32 adminRole;
    }

    mapping(bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Modifier that checks that an account has a specific role. Reverts
     * with a standardized message including the required role.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     *
     * _Available since v4.1._
     */
    modifier onlyRole(bytes32 role) {
        _checkRole(role);
        _;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IAccessControl).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
        return _roles[role].members[account];
    }

    /**
     * @dev Revert with a standard message if `_msgSender()` is missing `role`.
     * Overriding this function changes the behavior of the {onlyRole} modifier.
     *
     * Format of the revert message is described in {_checkRole}.
     *
     * _Available since v4.6._
     */
    function _checkRole(bytes32 role) internal view virtual {
        _checkRole(role, _msgSender());
    }

    /**
     * @dev Revert with a standard message if `account` is missing `role`.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     */
    function _checkRole(bytes32 role, address account) internal view virtual {
        if (!hasRole(role, account)) {
            revert(
                string(
                    abi.encodePacked(
                        "AccessControl: account ",
                        Strings.toHexString(account),
                        " is missing role ",
                        Strings.toHexString(uint256(role), 32)
                    )
                )
            );
        }
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     *
     * May emit a {RoleGranted} event.
     */
    function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     *
     * May emit a {RoleRevoked} event.
     */
    function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been revoked `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     *
     * May emit a {RoleRevoked} event.
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * May emit a {RoleGranted} event.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     *
     * NOTE: This function is deprecated in favor of {_grantRole}.
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        bytes32 previousAdminRole = getRoleAdmin(role);
        _roles[role].adminRole = adminRole;
        emit RoleAdminChanged(role, previousAdminRole, adminRole);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * Internal function without access restriction.
     *
     * May emit a {RoleGranted} event.
     */
    function _grantRole(bytes32 role, address account) internal virtual {
        if (!hasRole(role, account)) {
            _roles[role].members[account] = true;
            emit RoleGranted(role, account, _msgSender());
        }
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * Internal function without access restriction.
     *
     * May emit a {RoleRevoked} event.
     */
    function _revokeRole(bytes32 role, address account) internal virtual {
        if (hasRole(role, account)) {
            _roles[role].members[account] = false;
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/IAccessControl.sol)

pragma solidity ^0.8.0;

/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IAccessControl {
    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {AccessControl-_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) external view returns (bool);

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {AccessControl-_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) external view returns (bytes32);

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) external;
}

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

pragma solidity ^0.8.0;

import "../utils/Context.sol";

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

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

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

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

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

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

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

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (security/Pausable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @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 Pausable is Context {
    /**
     * @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.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        _requireNotPaused();
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        require(!paused(), "Pausable: paused");
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        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());
    }
}

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

pragma solidity ^0.8.0;

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

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

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

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

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

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

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/extensions/IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

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

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

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

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

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

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

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.3) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/IERC20Permit.sol";
import "../../../utils/Address.sol";

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

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    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));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance + value));
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    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");
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance - value));
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
     * to be set to zero before setting it to a non-zero value, such as USDT.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeWithSelector(token.approve.selector, spender, value);

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, 0));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Use a ERC-2612 signature to set the `owner` approval toward `spender` on `token`.
     * Revert on invalid signature.
     */
    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @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");
        require(returndata.length == 0 || abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
    }

    /**
     * @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).
     *
     * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // 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 cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return
            success && (returndata.length == 0 || abi.decode(returndata, (bool))) && Address.isContract(address(token));
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (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
     *
     * Furthermore, `isContract` will also return true if the target contract within
     * the same transaction is already scheduled for destruction by `SELFDESTRUCT`,
     * which only has an effect at the end of a transaction.
     * ====
     *
     * [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://consensys.net/diligence/blog/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/v0.8.0/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 functionCallWithValue(target, data, 0, "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");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or 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 {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // 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
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// 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;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

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

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    enum Rounding {
        Down, // Toward negative infinity
        Up, // Toward infinity
        Zero // Toward zero
    }

    /**
     * @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 == 0 ? 0 : (a - 1) / b + 1;
    }

    /**
     * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
     * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
     * with further edits by Uniswap Labs also under MIT license.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
            // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2^256 + prod0.
            uint256 prod0; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod0 := mul(x, y)
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                // Solidity will revert if denominator == 0, unlike the div opcode on its own.
                // The surrounding unchecked block does not change this fact.
                // See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            require(denominator > prod1, "Math: mulDiv overflow");

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0].
            uint256 remainder;
            assembly {
                // Compute remainder using mulmod.
                remainder := mulmod(x, y, denominator)

                // Subtract 256 bit number from 512 bit number.
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
            // See https://cs.stackexchange.com/q/138556/92363.

            // Does not overflow because the denominator cannot be zero at this stage in the function.
            uint256 twos = denominator & (~denominator + 1);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

                // Divide [prod1 prod0] by twos.
                prod0 := div(prod0, twos)

                // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                twos := add(div(sub(0, twos), twos), 1)
            }

            // Shift in bits from prod1 into prod0.
            prod0 |= prod1 * twos;

            // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
            // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
            // four bits. That is, denominator * inv = 1 mod 2^4.
            uint256 inverse = (3 * denominator) ^ 2;

            // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works
            // in modular arithmetic, doubling the correct bits in each step.
            inverse *= 2 - denominator * inverse; // inverse mod 2^8
            inverse *= 2 - denominator * inverse; // inverse mod 2^16
            inverse *= 2 - denominator * inverse; // inverse mod 2^32
            inverse *= 2 - denominator * inverse; // inverse mod 2^64
            inverse *= 2 - denominator * inverse; // inverse mod 2^128
            inverse *= 2 - denominator * inverse; // inverse mod 2^256

            // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
            // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
            // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inverse;
            return result;
        }
    }

    /**
     * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
        uint256 result = mulDiv(x, y, denominator);
        if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
            result += 1;
        }
        return result;
    }

    /**
     * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.
     *
     * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
     */
    function sqrt(uint256 a) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
        //
        // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
        // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
        //
        // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
        // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
        // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
        //
        // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
        uint256 result = 1 << (log2(a) >> 1);

        // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
        // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
        // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
        // into the expected uint128 result.
        unchecked {
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            return min(result, a / result);
        }
    }

    /**
     * @notice Calculates sqrt(a), following the selected rounding direction.
     */
    function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = sqrt(a);
            return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 128;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 64;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 32;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 16;
            }
            if (value >> 8 > 0) {
                value >>= 8;
                result += 8;
            }
            if (value >> 4 > 0) {
                value >>= 4;
                result += 4;
            }
            if (value >> 2 > 0) {
                value >>= 2;
                result += 2;
            }
            if (value >> 1 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log2(value);
            return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >= 10 ** 64) {
                value /= 10 ** 64;
                result += 64;
            }
            if (value >= 10 ** 32) {
                value /= 10 ** 32;
                result += 32;
            }
            if (value >= 10 ** 16) {
                value /= 10 ** 16;
                result += 16;
            }
            if (value >= 10 ** 8) {
                value /= 10 ** 8;
                result += 8;
            }
            if (value >= 10 ** 4) {
                value /= 10 ** 4;
                result += 4;
            }
            if (value >= 10 ** 2) {
                value /= 10 ** 2;
                result += 2;
            }
            if (value >= 10 ** 1) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log10(value);
            return result + (rounding == Rounding.Up && 10 ** result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256, rounded down, of a positive value.
     * Returns 0 if given 0.
     *
     * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
     */
    function log256(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 16;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 8;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 4;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 2;
            }
            if (value >> 8 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 256, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (rounding == Rounding.Up && 1 << (result << 3) < value ? 1 : 0);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/SignedMath.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard signed math utilities missing in the Solidity language.
 */
library SignedMath {
    /**
     * @dev Returns the largest of two signed numbers.
     */
    function max(int256 a, int256 b) internal pure returns (int256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two signed numbers.
     */
    function min(int256 a, int256 b) internal pure returns (int256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two signed numbers without overflow.
     * The result is rounded towards zero.
     */
    function average(int256 a, int256 b) internal pure returns (int256) {
        // Formula from the book "Hacker's Delight"
        int256 x = (a & b) + ((a ^ b) >> 1);
        return x + (int256(uint256(x) >> 255) & (a ^ b));
    }

    /**
     * @dev Returns the absolute unsigned value of a signed value.
     */
    function abs(int256 n) internal pure returns (uint256) {
        unchecked {
            // must be unchecked in order to support `n = type(int256).min`
            return uint256(n >= 0 ? n : -n);
        }
    }
}

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

pragma solidity ^0.8.0;

import "./math/Math.sol";
import "./math/SignedMath.sol";

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _SYMBOLS = "0123456789abcdef";
    uint8 private constant _ADDRESS_LENGTH = 20;

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = Math.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            /// @solidity memory-safe-assembly
            assembly {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                /// @solidity memory-safe-assembly
                assembly {
                    mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `int256` to its ASCII `string` decimal representation.
     */
    function toString(int256 value) internal pure returns (string memory) {
        return string(abi.encodePacked(value < 0 ? "-" : "", toString(SignedMath.abs(value))));
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, Math.log256(value) + 1);
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }

    /**
     * @dev Returns true if the two strings are equal.
     */
    function equal(string memory a, string memory b) internal pure returns (bool) {
        return keccak256(bytes(a)) == keccak256(bytes(b));
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/structs/EnumerableSet.sol)
// This file was procedurally generated from scripts/generate/templates/EnumerableSet.js.

pragma solidity ^0.8.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```solidity
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 *
 * [WARNING]
 * ====
 * Trying to delete such a structure from storage will likely result in data corruption, rendering the structure
 * unusable.
 * See https://github.com/ethereum/solidity/pull/11843[ethereum/solidity#11843] for more info.
 *
 * In order to clean an EnumerableSet, you can either remove all elements one by one or create a fresh instance using an
 * array of EnumerableSet.
 * ====
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;
        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping(bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) {
            // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            if (lastIndex != toDeleteIndex) {
                bytes32 lastValue = set._values[lastIndex];

                // Move the last value to the index where the value to delete is
                set._values[toDeleteIndex] = lastValue;
                // Update the index for the moved value
                set._indexes[lastValue] = valueIndex; // Replace lastValue's index to valueIndex
            }

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        return set._values[index];
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function _values(Set storage set) private view returns (bytes32[] memory) {
        return set._values;
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(Bytes32Set storage set) internal view returns (bytes32[] memory) {
        bytes32[] memory store = _values(set._inner);
        bytes32[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(AddressSet storage set) internal view returns (address[] memory) {
        bytes32[] memory store = _values(set._inner);
        address[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }

    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    /**
     * @dev Returns the value stored at position `index` in the set. O(1).
     *
     * Note that there are no guarantees on the ordering of values inside the
     * array, and it may change when more values are added or removed.
     *
     * Requirements:
     *
     * - `index` must be strictly less than {length}.
     */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }

    /**
     * @dev Return the entire set in an array
     *
     * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
     * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
     * this function has an unbounded cost, and using it as part of a state-changing function may render the function
     * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
     */
    function values(UintSet storage set) internal view returns (uint256[] memory) {
        bytes32[] memory store = _values(set._inner);
        uint256[] memory result;

        /// @solidity memory-safe-assembly
        assembly {
            result := store
        }

        return result;
    }
}

// SPDX-License-Identifier: BSD-3-Clause
pragma solidity 0.8.16;

import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "contracts/vesting/Interfaces/IReleaser.sol";

/**
 * @title Releaser
 */
abstract contract AbstractReleaser is IReleaser, Ownable {
    using SafeERC20 for IERC20;

    IERC20 internal immutable _token;
    address internal immutable _beneficiary;
    uint256 internal _erc20Released;

    event ERC20Released(address _token, uint256 _amount);

    /**
     * @dev Set the beneficiary, and token for vesting
     */
    constructor(address beneficiaryAddress, address erc20Token) {
        require(erc20Token != address(0), "Releaser: token cannot be the zero address");
        require(beneficiaryAddress != address(0), "Releaser: beneficiary is zero address");

        _token = IERC20(erc20Token);
        _beneficiary = beneficiaryAddress;
    }

    /**
     * @dev Release the tokens that have already vested.
     *
     * Emits a {ERC20Released} event.
     */
    function release() external virtual {
        uint256 _releasable = vestedAmount(block.timestamp) - released();
        _erc20Released += _releasable;
        emit ERC20Released(ERC20token(), _releasable);
        if (_releasable > 0) {
            _token.safeTransfer(beneficiary(), _releasable);
        }
    }

    /**
     * @dev Withdraw the tokens that have already vested.
     * Only in emergency or refund period.
     * @param _to Address to withdraw tokens to. This will be the owner of main Vesting contract.
     * @param _amount Amount of tokens to withdraw.
     */
    function emergencyWithdraw(address _to, uint256 _amount) external onlyOwner {
        _token.safeTransfer(_to, _amount);
    }

    function reduceReleasedAmount(uint256 _amount) external {
        require(msg.sender == _beneficiary, "Releaser: only beneficiary can call this function");
        _erc20Released -= _amount;
    }

    /**
     * @dev Calculates the amount of tokens that has already vested.
     */
    function vestedAmount(uint256 timestamp) public view virtual returns (uint256);

    /**
     * @dev Getter for the token address.
     */
    function ERC20token() public view virtual returns (address) {
        return address(_token);
    }

    /**
     * @dev Getter for the beneficiary address.
     */
    function beneficiary() public view virtual returns (address) {
        return _beneficiary;
    }

    /**
     * @dev Amount of token already released
     */
    function released() public view virtual returns (uint256) {
        return _erc20Released;
    }

    function releasable() public view virtual returns (uint256) {
        return vestedAmount(block.timestamp) - released();
    }
}

// SPDX-License-Identifier: BSD-3-Clause
pragma solidity 0.8.16;

import "@chainlink/contracts/src/v0.8/KeeperCompatible.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
import "@openzeppelin/contracts/access/AccessControl.sol";
import "@openzeppelin/contracts/security/Pausable.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "contracts/vesting/Interfaces/IVesting.sol";
import "contracts/vesting/Interfaces/IReleaser.sol";
import "@openzeppelin/contracts/utils/structs/EnumerableSet.sol";

/**
 * @title Vesting
 */
abstract contract AbstractVesting is
    IVesting,
    Pausable,
    AccessControl,
    ReentrancyGuard,
    KeeperCompatibleInterface
{
    using SafeERC20 for IERC20;
    using SafeERC20 for IERC20Metadata;
    using EnumerableSet for EnumerableSet.AddressSet;

    bytes32 public constant AIRDROPPER = keccak256("AIRDROPPER");
    uint256 public tge;
    /// @notice The redund period in seconds after TGE
    uint256 public refundPeriod;

    IReleaser internal releaser;
    IERC20 internal token;
    IERC20Metadata public immutable refundToken;

    uint256 internal _totalShares;
    uint256 internal _totalReleased;

    mapping(address => uint256) internal _shares;
    mapping(address => uint256) internal _released;
    EnumerableSet.AddressSet internal _refundees;

    uint256 public claimFee;
    address payable public feeReserve;
    address public refundReserve;

    EnumerableSet.AddressSet private _autoAirdrops;
    uint256 public airdropFee;
    bool public airdropAllowed;

    /// @dev The bool to determine if auto compounding is active
    bool internal iterationActive;
    /// @dev The index of the address to start the auroAirdrop iteration from
    uint256 internal autoAirdropIndex;
    /// @dev The number of addresses to iterate through in each auroAirdrop iteration
    uint256 internal addressCountPerIteration = 50;

    event PaymentReleased(address to, uint256 amount);
    event Airdropped(address to, uint256 amount);

    modifier onlyInRefundPeriod() {
        require(
            (block.timestamp < refundPeriod + tge) && (block.timestamp >= tge),
            "Refund is not open"
        );
        _;
    }

    constructor(
        address _token,
        address _refundToken,
        address _refundReserve,
        address _feeReserve,
        uint256 _tge,
        uint256 _cliff,
        uint256 _durationInSec,
        uint256 _periodInSeconds,
        uint256 _refundPeriod
    ) {
        require(_token != address(0), "Token address cannot be 0");
        require(_refundReserve != address(0), "Refund reserve cannot be the zero address");
        require(_feeReserve != address(0), "Fee reserve cannot be the zero address");

        _grantRole(DEFAULT_ADMIN_ROLE, msg.sender);
        _grantRole(AIRDROPPER, msg.sender);

        token = IERC20(_token);
        releaser = IReleaser(deployReleaser(_cliff, _durationInSec, _periodInSeconds));
        refundToken = IERC20Metadata(_refundToken);
        refundReserve = _refundReserve;
        feeReserve = payable(_feeReserve);
        tge = _tge;
        refundPeriod = _refundPeriod;
        airdropFee = 10 * refundToken.decimals();
    }

    function withdrawAccidentalTokens(
        address _token,
        address _to,
        uint256 _amount
    ) external onlyRole(DEFAULT_ADMIN_ROLE) {
        require(_token != address(0), "Vesting: token is the zero address");
        require(_to != address(0), "Vesting: recipient is the zero address");
        IERC20(_token).safeTransfer(_to, _amount);
    }

    function deployReleaser(
        uint256 _cliff,
        uint256 _durationInSec,
        uint256 _periodInSeconds
    ) public virtual returns (address newReleaserAddress);

    function setAirdropStatus(bool _allowed) external onlyRole(DEFAULT_ADMIN_ROLE) {
        airdropAllowed = _allowed;
    }

    function updateIterationNumber(uint256 iteration) external onlyRole(DEFAULT_ADMIN_ROLE) {
        addressCountPerIteration = iteration;
    }

    function setRefundPeriod(uint256 _refundPeriod) external onlyRole(DEFAULT_ADMIN_ROLE) {
        refundPeriod = _refundPeriod;
    }

    function updateReleaser(address _releaser) external onlyRole(DEFAULT_ADMIN_ROLE) {
        require(_releaser != address(0), "Vesting: releaser cannot be the zero address");
        releaser = IReleaser(_releaser);
    }

    function setRefundReserve(address _refundReserve) external onlyRole(DEFAULT_ADMIN_ROLE) {
        require(_refundReserve != address(0), "Vesting: refund reserve cannot be the zero address");
        refundReserve = _refundReserve;
    }

    function setFeeReserve(address _feeReserve) external onlyRole(DEFAULT_ADMIN_ROLE) {
        require(_feeReserve != address(0), "Vesting: fee reserve cannot be the zero address");
        feeReserve = payable(_feeReserve);
    }

    function setClaimFee(uint256 _fee) external onlyRole(DEFAULT_ADMIN_ROLE) {
        require(_fee < 1 ether, "Vesting: claim fee is too high");
        claimFee = _fee;
    }

    function setAirdropFee(uint256 _fee) external onlyRole(DEFAULT_ADMIN_ROLE) {
        require(_fee < 100 * refundToken.decimals(), "Vesting: airdrop fee is too high");
        airdropFee = _fee;
    }

    function emergencyWithdraw(
        uint256 _amount,
        bool _fromReleaser
    ) external onlyRole(DEFAULT_ADMIN_ROLE) {
        if (_fromReleaser) {
            releaser.emergencyWithdraw(msg.sender, _amount);
        } else {
            token.safeTransfer(msg.sender, _amount);
        }
    }

    function replaceWallet(
        address _oldWallet,
        address _newWallet
    ) external onlyRole(DEFAULT_ADMIN_ROLE) {
        require(_oldWallet != address(0), "Vesting: old wallet is the zero address");
        require(_newWallet != address(0), "Vesting: new wallet is the zero address");
        require(_shares[_oldWallet] > 0, "Vesting: old wallet has no shares");

        uint256 oldShares = _shares[_oldWallet];
        _shares[_oldWallet] = 0;
        _shares[_newWallet] = oldShares;

        uint256 oldReleased = _released[_oldWallet];
        _released[_oldWallet] = 0;
        _released[_newWallet] = oldReleased;

        emit SharesUpdated(_oldWallet, 0);
        emit SharesUpdated(_newWallet, oldShares);
    }

    function updateTimes(
        uint256 _tge,
        uint256 _cliff,
        uint256 _durationInSec,
        uint256 _periodInSeconds
    ) external virtual onlyRole(DEFAULT_ADMIN_ROLE) {
        if (_tge > 0) {
            tge = _tge;
        }
        if (_cliff > 0) {
            releaser.updateStartTime(_cliff);
        }
        if (_durationInSec > 0) {
            releaser.updateDuration(_durationInSec);
        }
        if (_periodInSeconds > 0) {
            releaser.updatePeriods(_periodInSeconds);
        }
    }

    function addVestingInstances(
        uint256[] memory unlockTimes,
        uint256[] memory percents
    ) external onlyRole(DEFAULT_ADMIN_ROLE) {
        releaser.addVestingInstances(unlockTimes, percents);
    }

    function airdrop(address[] memory _accounts) external onlyRole(AIRDROPPER) {
        releaser.release();
        for (uint256 i = 0; i < _accounts.length; i++) {
            uint256 payment = releasable(_accounts[i]);
            if (payment > 0) {
                _release(_accounts[i], _accounts[i]);
                emit Claimed(_accounts[i], payment);
            }
        }
    }

    function batchAddAirdrops(address[] memory _accounts) external onlyRole(DEFAULT_ADMIN_ROLE) {
        for (uint256 i = 0; i < _accounts.length; i++) {
            addAirdrop(_accounts[i]);
        }
    }

    function batchRemoveAirdrops(address[] memory _accounts) external onlyRole(DEFAULT_ADMIN_ROLE) {
        for (uint256 i = 0; i < _accounts.length; i++) {
            removeAirdrop(_accounts[i]);
        }
    }

    function addAirdrop(address _account) public onlyRole(DEFAULT_ADMIN_ROLE) {
        require(
            !_autoAirdrops.contains(_account),
            "Vesting: account has already requested airdrop"
        );
        require(_shares[_account] > 0, "Vesting: account has no shares");

        _autoAirdrops.add(_account);
    }

    function removeAirdrop(address _account) public onlyRole(DEFAULT_ADMIN_ROLE) {
        require(_autoAirdrops.contains(_account), "Vesting: account has not requested airdrop");
        _autoAirdrops.remove(_account);
    }

    function requestAirdrop() external nonReentrant {
        require(airdropAllowed, "Vesting: airdrop is not allowed");
        require(
            !_autoAirdrops.contains(msg.sender),
            "Vesting: account has already requested airdrop"
        );
        require(_shares[msg.sender] > 0, "Vesting: account has no shares");

        _autoAirdrops.add(msg.sender);
        refundToken.safeTransferFrom(msg.sender, feeReserve, airdropFee);
    }

    /**
     * @dev See {IVesting-claim}.
     */
    function claim() public payable nonReentrant whenNotPaused {
        require(block.timestamp >= tge, "Vesting: TGE has not happened yet");
        require(msg.value >= claimFee, "Vesting: claim fee is not enough");

        releaser.release();
        uint256 payment = releasable(msg.sender);
        _release(msg.sender, msg.sender);

        if (claimFee > 0) {
            (bool sent, ) = feeReserve.call{value: claimFee}("");
            require(sent, "Failed to send fee");
        }

        // Refund any excess Ether sent
        uint256 refundAmount = msg.value - claimFee;
        if (refundAmount > 0) {
            (bool refundSuccess, ) = msg.sender.call{value: refundAmount}("");
            require(refundSuccess, "Refund failed");
        }
        emit Claimed(msg.sender, payment);
    }

    function claimTo(address _receiver) external payable nonReentrant whenNotPaused {
        require(block.timestamp >= tge, "Vesting: TGE has not happened yet");
        require(msg.value >= claimFee, "Vesting: claim fee is not enough");

        releaser.release();
        uint256 payment = releasable(msg.sender);
        _release(msg.sender, _receiver);

        if (claimFee > 0) {
            (bool sent, ) = feeReserve.call{value: claimFee}("");
            require(sent, "Failed to send fee");
        }

        // Refund any excess Ether sent
        uint256 refundAmount = msg.value - claimFee;
        if (refundAmount > 0) {
            (bool refundSuccess, ) = msg.sender.call{value: refundAmount}("");
            require(refundSuccess, "Refund failed");
        }
        emit Claimed(msg.sender, payment);
    }

    function getRefund() external virtual nonReentrant whenNotPaused onlyInRefundPeriod {
        require(claimedOf(msg.sender) == 0, "Vesting: account has already claimed");
        require(!_refundees.contains(msg.sender), "Vesting: account has already been refunded");
        require(_shares[msg.sender] > 0, "Vesting: account has no shares");

        _refundUser(msg.sender);
    }

    /**
     * @dev Function to remove shares from an arrayof accounts and transfer the tokens to the admin.
     * emits {Refunded} event.
     * @param _accounts addresses of the accounts.
     */
    function refundUsers(address[] memory _accounts) external onlyRole(DEFAULT_ADMIN_ROLE) {
        for (uint256 i = 0; i < _accounts.length; i++) {
            if (_refundees.contains(_accounts[i])) {
                continue;
            } else {
                _refundUser(_accounts[i]);
            }
        }
    }

    // ACCESS CONTROL FUNCTIONS

    function pause() external onlyRole(DEFAULT_ADMIN_ROLE) {
        _pause();
    }

    function unpause() external onlyRole(DEFAULT_ADMIN_ROLE) {
        _unpause();
    }

    function batchSetShares(address[] memory _accounts, uint256[] memory _shares_) external {
        require(_accounts.length == _shares_.length, "Vesting: arrays length mismatch");
        for (uint256 i = 0; i < _accounts.length; i++) {
            setShares(_accounts[i], _shares_[i]);
        }
    }

    function batchAddShares(address[] memory _accounts, uint256[] memory _shares_) external {
        require(_accounts.length == _shares_.length, "Vesting: arrays length mismatch");
        for (uint256 i = 0; i < _accounts.length; i++) {
            addShares(_accounts[i], _shares_[i]);
        }
    }

    function batchRemoveShares(address[] memory _accounts) external {
        for (uint256 i = 0; i < _accounts.length; i++) {
            removeShares(_accounts[i]);
        }
    }

    function checkUpkeep(
        bytes calldata /* checkData */
    ) external view override returns (bool upkeepNeeded, bytes memory performData) {
        upkeepNeeded = iterationActive;
        return (upkeepNeeded, "");
        // We don't use the checkData in this example. The checkData is defined when the Upkeep was registered.
    }

    function performUpkeep(bytes calldata /* performData */) external override {
        //We highly recommend revalidating the upkeep in the performUpkeep function
        if (iterationActive) {
            autoAirdrop();
        }
        // We don't use the performData in this example. The performData is generated by the Keeper's call to your checkUpkeep function
    }

    function autoAirdrop() public {
        uint256 usersLeft = _autoAirdrops.length() - autoAirdropIndex;
        uint256 startIndex = autoAirdropIndex;
        uint256 remainingCount;
        if (usersLeft > addressCountPerIteration) {
            iterationActive = true;
            autoAirdropIndex = autoAirdropIndex + addressCountPerIteration;
            remainingCount = addressCountPerIteration;
        } else {
            iterationActive = false;
            remainingCount = usersLeft;
            autoAirdropIndex = 0;
        }
        releaser.release();
        for (uint256 i = startIndex; i < startIndex + remainingCount; i++) {
            address user = _autoAirdrops.at(i);
            _autoAirdrop(user);
        }
    }

    function canRequestAirdrop() external view override returns (bool) {
        return
            (airdropAllowed) &&
            (block.timestamp >= tge) &&
            (_shares[msg.sender] > 0) &&
            (!_autoAirdrops.contains(msg.sender));
    }

    function canRequestAirdropOf(address _user) external view override returns (bool) {
        return
            (airdropAllowed) &&
            (block.timestamp >= tge) &&
            (_shares[_user] > 0) &&
            (!_autoAirdrops.contains(_user));
    }

    /**
     * @dev See {IVesting-claimableOf}.
     */
    function claimableOf(address _account) external view returns (uint256) {
        return releasable(_account);
    }

    /**
     * @dev Function to get the vesting releaser contract.
     * @return address of the releaser contract.
     */
    function getReleaser() external view returns (address) {
        return address(releaser);
    }

    /**
     * @dev Function to get the vesting token contract.
     * @return address of the token contract.
     */
    function getTokenAddress() external view returns (address) {
        return address(token);
    }

    /**
     * @dev Getter for the amount of shares held by an account.
     */
    function shares(address account) external view returns (uint256) {
        return _shares[account];
    }

    function getTotalShares() external view returns (uint256) {
        return _totalShares;
    }

    function getRefundeeNumber() external view returns (uint256) {
        return _refundees.length();
    }

    function getRefundees(uint _start, uint _end) external view returns (address[] memory) {
        uint256 refundeesCount = _refundees.length();
        require(_start < refundeesCount, "Vesting: start is greater than refundees length");
        if (_end > refundeesCount) {
            _end = refundeesCount;
        }

        address[] memory _refs = new address[](_end - _start);
        for (uint i = _start; i < _end; i++) {
            _refs[i - _start] = _refundees.at(i);
        }
        return _refs;
    }

    function getAutoAirdropNumber() external view returns (uint256) {
        return _autoAirdrops.length();
    }

    function getAutoAirdrops(uint _start, uint _end) external view returns (address[] memory) {
        uint256 airdropsCount = _autoAirdrops.length();
        require(_start < airdropsCount, "Vesting: start is greater than airdrops length");
        if (_end > airdropsCount) {
            _end = airdropsCount;
        }

        address[] memory _drops = new address[](_end - _start);
        for (uint i = _start; i < _end; i++) {
            _drops[i - _start] = _autoAirdrops.at(i);
        }
        return _drops;
    }

    function canRequestRefund() external view virtual returns (bool) {
        return
            (block.timestamp < refundPeriod + tge) &&
            (block.timestamp >= tge) &&
            (_shares[msg.sender] > 0) &&
            (!_refundees.contains(msg.sender)) &&
            (claimedOf(msg.sender) == 0);
    }

    function canRequestRefundOf(address _account) external view virtual returns (bool) {
        return
            (block.timestamp < refundPeriod + tge) &&
            (block.timestamp >= tge) &&
            (_shares[_account] > 0) &&
            (!_refundees.contains(_account)) &&
            (claimedOf(_account) == 0);
    }

    function hasRequestedRefund(address _account) external view override returns (bool) {
        return _refundees.contains(_account);
    }

    /**
     * @dev See {IVesting-setShares}.
     */
    function setShares(
        address _account,
        uint256 shares_
    ) public virtual onlyRole(DEFAULT_ADMIN_ROLE) {
        require(_account != address(0), "Vesting: account is the zero address");
        require(shares_ > 0, "Vesting: shares are 0");

        uint256 oldShares = _shares[_account];
        _shares[_account] = shares_;
        _totalShares = _totalShares + shares_ - oldShares;
        emit SharesUpdated(_account, shares_);
    }

    /**
     * @dev See {IVesting-addShares}.
     */
    function addShares(
        address _account,
        uint256 _amount
    ) public virtual onlyRole(DEFAULT_ADMIN_ROLE) {
        require(_account != address(0), "Vesting: account is the zero address");
        require(_amount > 0, "Vesting: shares are 0");

        _shares[_account] += _amount;
        _totalShares += _amount;
        emit SharesAdded(_account, _amount);
    }

    /**
     * @dev See {IVesting-removeShares}.
     */
    function removeShares(address _account) public onlyRole(DEFAULT_ADMIN_ROLE) {
        _removeShares(_account);
    }

    /**
     * @dev See {IVesting-totalClaimableOf}.
     */
    function totalClaimableOf(address _account) public view returns (uint256) {
        uint256 totalAmount = token.balanceOf(address(this)) +
            token.balanceOf(address(releaser)) +
            _totalReleased;
        return _shareOf(_account, totalAmount);
    }

    /**
     * @dev See {IVesting-claimedOf}.
     */
    function claimedOf(address _account) public view returns (uint256) {
        return _released[_account];
    }

    function _autoAirdrop(address _account) internal {
        require(_autoAirdrops.contains(_account), "Vesting: account has not requested airdrop");
        require(_shares[_account] > 0, "Vesting: account has no shares");

        uint256 payment = releasable(_account);
        if (payment > 0) {
            _release(_account, _account);
            emit Airdropped(_account, payment);
        }
    }

    /**
     * @dev Function to handle refund mechanics.
     * @param _account address of the account.
     */
    function _refundUser(address _account) internal virtual;

    /**
     * @dev Triggers a transfer to `account` of the amount of `token` tokens they are owed, according to their
     * percentage of the total shares and their previous withdrawals. `token` must be the address of an IERC20
     * contract.
     */
    function _release(address account, address _receiver) internal virtual {
        require(_shares[account] > 0, "Vesting: account has no shares");

        uint256 payment = releasable(account);

        require(payment != 0, "Vesting: account is not due payment");

        _released[account] += payment;
        _totalReleased += payment;

        token.safeTransfer(_receiver, payment);
        emit PaymentReleased(_receiver, payment);
    }

    function _removeShares(address _account) internal {
        require(_account != address(0), "Vesting: account is the zero address");
        uint256 totalReleasedReleaser = (releaser.released() * _shares[_account]) / _totalShares;
        uint256 oldShares = _shares[_account];

        _shares[_account] = 0;
        _totalShares -= oldShares;
        _totalReleased -= _released[_account];
        _released[_account] = 0;
        releaser.reduceReleasedAmount(totalReleasedReleaser);
        emit SharesUpdated(_account, 0);
    }

    /**
     * @dev Getter for the amount of shares in tokens with respect to total amounts.
     * @param _account address of the account.
     * @param _amount amount of total tokens.
     * @return amount of tokens account can receive.
     */
    function _shareOf(address _account, uint256 _amount) internal view returns (uint256) {
        return (_amount * _shares[_account]) / _totalShares;
    }

    /**
     * @dev Getter for the amount of payee's releasable `token` tokens. `token` should be the address of an
     * IERC20 contract.
     */
    function releasable(address account) internal view returns (uint256) {
        uint256 totalReceived = token.balanceOf(address(this)) +
            _totalReleased +
            releaser.releasable();
        return _pendingPayment(account, totalReceived, _released[account]);
    }

    /**
     * @dev internal logic for computing the pending payment of an `account` given the token historical balances and
     * already released amounts.
     */
    function _pendingPayment(
        address account,
        uint256 totalReceived,
        uint256 alreadyReleased
    ) internal view returns (uint256) {
        return (totalReceived * _shares[account]) / _totalShares - alreadyReleased;
    }
}

// SPDX-License-Identifier: BSD-3-Clause
pragma solidity 0.8.16;

import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "contracts/vesting/AbstractReleaser.sol";

/**
 * @title Releaser
 */
contract CustomReleaser is AbstractReleaser {
    using SafeERC20 for IERC20;

    struct VestingInstance {
        uint256 unlockTime;
        uint256 percent;
    }
    uint16 public constant PERCENTAGE_FACTOR = 10000; // 100%. So to imply 22.5% you should use 2250.

    VestingInstance[] public vestingInstances;

    /**
     * @dev Set the beneficiary, start timestamp and vesting duration of the vesting wallet.
     */
    constructor(
        address beneficiaryAddress,
        address erc20Token
    ) AbstractReleaser(beneficiaryAddress, erc20Token) {}

    function updateStartTime(uint256 startTimestamp) external onlyOwner {
        revert("This contract uses exact timestamps for unlocks.");
    }

    function updateDuration(uint256 durationSeconds) external onlyOwner {
        revert("This contract uses exact timestamps for unlocks.");
    }

    function updatePeriods(uint256 periodInSeconds) external onlyOwner {
        revert("This contract uses exact timestamps for unlocks.");
    }

    function addVestingInstances(
        uint256[] memory unlockTimes,
        uint256[] memory percents
    ) external onlyOwner {
        require(
            unlockTimes.length == percents.length,
            "Releaser: unlockTimes and amounts length mismatch"
        );

        for (uint256 i = 0; i < unlockTimes.length; i++) {
            vestingInstances.push(VestingInstance(unlockTimes[i], percents[i]));
        }
    }

    /**
     * @dev Calculates the amount of tokens that has already vested.
     */
    function vestedAmount(uint256 timestamp) public view override returns (uint256) {
        uint256 totalVestedAmount = 0;
        uint256 totalReleasableAmount = _token.balanceOf(address(this)) + released();

        for (uint256 i = 0; i < vestingInstances.length; i++) {
            if (vestingInstances[i].unlockTime <= timestamp) {
                totalVestedAmount +=
                    (vestingInstances[i].percent * totalReleasableAmount) /
                    PERCENTAGE_FACTOR;
            }
        }
        return totalVestedAmount;
    }
}

// SPDX-License-Identifier: BSD-3-Clause
pragma solidity 0.8.16;

import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
import "contracts/vesting/AbstractVesting.sol";
import "contracts/vesting/CustomReleaser.sol";

/**
 * @title Vesting
 */
contract CustomVesting is AbstractVesting {
    using SafeERC20 for IERC20;
    using SafeERC20 for IERC20Metadata;
    using EnumerableSet for EnumerableSet.AddressSet;

    constructor(
        address _token,
        address _refundToken,
        address _refundReserve,
        address _feeReserve,
        uint256 _tge,
        uint256 _cliff,
        uint256 _durationInSec,
        uint256 _periodInSeconds,
        uint256 _refundPeriod
    )
        AbstractVesting(
            _token,
            _refundToken,
            _refundReserve,
            _feeReserve,
            _tge,
            _cliff,
            _durationInSec,
            _periodInSeconds,
            _refundPeriod
        )
    {}

    function deployReleaser(
        uint256 _cliff,
        uint256 _durationInSec,
        uint256 _periodInSeconds
    ) public override onlyRole(DEFAULT_ADMIN_ROLE) returns (address newReleaserAddress) {
        CustomReleaser newReleaser = new CustomReleaser(address(this), address(token));

        return address(newReleaser);
    }

    /**
     * @dev Function to remove shares from an account and transfer the tokens to the admin.
     * emits {Refunded} event.
     * @param _account address of the account.
     */
    function _refundUser(address _account) internal override {
        require(releaser.released() == 0, "Cliff has ended");
        require(releaser.releasable() == 0, "Vesting: releaser has releasable tokens");

        if (claimedOf(_account) > 0) {
            return;
        } else {
            _refundees.add(_account);

            uint256 payment = releasable(_account);
            uint256 notClaimed = totalClaimableOf(_account);
            uint256 share = _shares[_account];
            _removeShares(_account);

            releaser.emergencyWithdraw(refundReserve, notClaimed - payment);
            token.safeTransfer(refundReserve, payment);
            refundToken.safeTransferFrom(refundReserve, _account, share);
            emit Refunded(_account, notClaimed);
        }
    }
}

// SPDX-License-Identifier: BSD-3-Clause
pragma solidity 0.8.16;

interface ILegacyVesting {
    event Claimed(address account, uint256 amount);
    event Refunded(address account, uint256 amount);
    event RefundRequested(address account);
    event SharesAdded(address account, uint256 amount);
    event SharesUpdated(address account, uint256 newShares);

    /**
     * @dev Transfers currently claimable tokens to the sender
     * emits {Claimed} event.
     */
    function claim() external payable;

    /**
     * @dev Returns `true` if users can request a refund
     */
    function canRequestRefund() external view returns (bool);

    /**
     * @dev checks if `_acount` has requested a refund
     */
    function hasRequestedRefund(address _account) external view returns (bool);

    /**
     * @dev Gets and stores a refund request for the sender
     * emits {RefundRequested} event.
     */
    function getRefund() external;

    /**
     * @notice Sets `_amount` shares to `_account` independent of their previous shares.
     * @dev Even if `_account` has shares, it will be set to `_amount`.
     * emits {SharesUpdated} event.
     * @param _account The account to set shares to
     * @param _amount The amount of shares to set
     */
    function setShares(address _account, uint256 _amount) external;

    /**
     * @notice Adds `_amount` shares to `_account`.
     * @dev If `_account` has no shares, it will be added to the list of shareholders.
     * emits {SharesAdded} event.
     * @param _account The account to add shares to
     * @param _amount The amount of shares to add
     */
    function addShares(address _account, uint256 _amount) external;

    /**
     * @notice Removes `_amount` shares from `_account`.
     * @dev If `_account` has no shares, it will be removed from the list of shareholders.
     * emits {SharesUpdated} event.
     * @param _account The account to remove shares from
     */
    function removeShares(address _account) external;

    /**
     * @dev Returns amount of tokens that can be claimed by `_account`
     */
    function claimableOf(address _account) external view returns (uint256);

    /**
     * @dev Returns total amount of tokens that can be claimed by `_account`
     */
    function totalClaimableOf(address _account) external view returns (uint256);

    /**
     * @dev Returns amount of tokens that has been claimed by `_account`
     */
    function claimedOf(address _account) external view returns (uint256);
}

// SPDX-License-Identifier: BSD-3-Clause
pragma solidity 0.8.16;

interface IReleaser {
    function emergencyWithdraw(address _to, uint256 _amount) external;

    function updateStartTime(uint256 startTimestamp) external;

    function updateDuration(uint256 durationSeconds) external;

    function updatePeriods(uint256 periodInSeconds) external;

    function addVestingInstances(uint256[] memory unlockTimes, uint256[] memory percents) external;

    function release() external;

    function reduceReleasedAmount(uint256 _amount) external;

    function releasable() external view returns (uint256);

    function released() external view returns (uint256);
}

// SPDX-License-Identifier: BSD-3-Clause
pragma solidity 0.8.16;

import "contracts/vesting/Interfaces/ILegacyVesting.sol";

interface IVesting is ILegacyVesting {
    /**
     * @dev Transfers currently claimable tokens to the `_receiver`
     * emits {Claimed} event.
     */
    function claimTo(address _receiver) external payable;

    function requestAirdrop() external;

    function canRequestAirdrop() external view returns (bool);

    function canRequestAirdropOf(address _user) external view returns (bool);
}