Contract Address Details

// SPDX-License-Identifier: UNLICENSED

/* 
*This code is subject to the Copyright License
* Copyright (c) 2023 Sevenlinelabs
* All rights reserved.
*/

pragma solidity ^0.8.17;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@thirdweb-dev/contracts/extension/PermissionsEnumerable.sol";
import "@thirdweb-dev/contracts/extension/Multicall.sol";

/**
 * @title NTSRewardVault
 * @dev Contract to manage the rewards tokens accepted and transferred in the system.
 */
contract NTSRewardVault is PermissionsEnumerable, Multicall {
    using SafeERC20 for IERC20;
    IERC20 private _acceptedToken;

    /**
     * @dev Initializes the contract by setting the acceptedToken and granting the DEFAULT_ADMIN_ROLE to the deployer.
     * @param acceptedToken The token that will be accepted and transferred as reward.
     */
    constructor(IERC20 acceptedToken, address _admin) {
        _acceptedToken = acceptedToken;
        _setupRole(DEFAULT_ADMIN_ROLE, _admin);
    }

    /**
     * @dev Allows anyone to deposit tokens into the contract as a reward.
     * @param amount The amount of tokens to be transferred.
     */
    function receiveToken(uint256 amount) external {
        _acceptedToken.safeTransferFrom(msg.sender, address(this), amount);
    }

    /**
     * @dev Allows the DEFAULT_ADMIN_ROLE to transfer tokens as rewards to a recipient.
     * @param recipient The address to which the tokens will be transferred.
     * @param amount The amount of tokens to be transferred.
     */
    function transferToken(address recipient, uint256 amount) external onlyRole(DEFAULT_ADMIN_ROLE){
        _acceptedToken.safeTransfer(recipient, amount);
    }

    /**
     * @dev Returns the balance of the acceptedToken held in the contract.
     * @return The balance of the acceptedToken.
     */
    function getTokenBalance() public view returns (uint256) {
        return _acceptedToken.balanceOf(address(this));
    }

    /**
     * @dev Allows the DEFAULT_ADMIN_ROLE to set a new address to the DEFAULT_ADMIN_ROLE.
     * @param _address The address to which the DEFAULT_ADMIN_ROLE will be granted.
     */
    function setRole(address _address) external onlyRole(DEFAULT_ADMIN_ROLE){
        _setupRole(DEFAULT_ADMIN_ROLE, _address);
    }
}
        

// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.0;

/// @author thirdweb

import "./IPermissions.sol";

/**
 * @dev External interface of AccessControlEnumerable declared to support ERC165 detection.
 */
interface IPermissionsEnumerable is IPermissions {
    /**
     * @dev Returns one of the accounts that have `role`. `index` must be a
     * value between 0 and {getRoleMemberCount}, non-inclusive.
     *
     * Role bearers are not sorted in any particular way, and their ordering may
     * change at any point.
     *
     * WARNING: When using {getRoleMember} and {getRoleMemberCount}, make sure
     * you perform all queries on the same block. See the following
     * [forum post](https://forum.openzeppelin.com/t/iterating-over-elements-on-enumerableset-in-openzeppelin-contracts/2296)
     * for more information.
     */
    function getRoleMember(bytes32 role, uint256 index) external view returns (address);

    /**
     * @dev Returns the number of accounts that have `role`. Can be used
     * together with {getRoleMember} to enumerate all bearers of a role.
     */
    function getRoleMemberCount(bytes32 role) external view returns (uint256);
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-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: Apache-2.0
pragma solidity ^0.8.0;

/// @author thirdweb

/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IPermissions {
    /**
     * @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: Apache-2.0
pragma solidity ^0.8.0;

/// @author thirdweb

import "./interface/IPermissionsEnumerable.sol";
import "./Permissions.sol";

/**
 *  @title   PermissionsEnumerable
 *  @dev     This contracts provides extending-contracts with role-based access control mechanisms.
 *           Also provides interfaces to view all members with a given role, and total count of members.
 */
contract PermissionsEnumerable is IPermissionsEnumerable, Permissions {
    /**
     *  @notice A data structure to store data of members for a given role.
     *
     *  @param index    Current index in the list of accounts that have a role.
     *  @param members  map from index => address of account that has a role
     *  @param indexOf  map from address => index which the account has.
     */
    struct RoleMembers {
        uint256 index;
        mapping(uint256 => address) members;
        mapping(address => uint256) indexOf;
    }

    /// @dev map from keccak256 hash of a role to its members' data. See {RoleMembers}.
    mapping(bytes32 => RoleMembers) private roleMembers;

    /**
     *  @notice         Returns the role-member from a list of members for a role,
     *                  at a given index.
     *  @dev            Returns `member` who has `role`, at `index` of role-members list.
     *                  See struct {RoleMembers}, and mapping {roleMembers}
     *
     *  @param role     keccak256 hash of the role. e.g. keccak256("TRANSFER_ROLE")
     *  @param index    Index in list of current members for the role.
     *
     *  @return member  Address of account that has `role`
     */
    function getRoleMember(bytes32 role, uint256 index) external view override returns (address member) {
        uint256 currentIndex = roleMembers[role].index;
        uint256 check;

        for (uint256 i = 0; i < currentIndex; i += 1) {
            if (roleMembers[role].members[i] != address(0)) {
                if (check == index) {
                    member = roleMembers[role].members[i];
                    return member;
                }
                check += 1;
            } else if (hasRole(role, address(0)) && i == roleMembers[role].indexOf[address(0)]) {
                check += 1;
            }
        }
    }

    /**
     *  @notice         Returns total number of accounts that have a role.
     *  @dev            Returns `count` of accounts that have `role`.
     *                  See struct {RoleMembers}, and mapping {roleMembers}
     *
     *  @param role     keccak256 hash of the role. e.g. keccak256("TRANSFER_ROLE")
     *
     *  @return count   Total number of accounts that have `role`
     */
    function getRoleMemberCount(bytes32 role) external view override returns (uint256 count) {
        uint256 currentIndex = roleMembers[role].index;

        for (uint256 i = 0; i < currentIndex; i += 1) {
            if (roleMembers[role].members[i] != address(0)) {
                count += 1;
            }
        }
        if (hasRole(role, address(0))) {
            count += 1;
        }
    }

    /// @dev Revokes `role` from `account`, and removes `account` from {roleMembers}
    ///      See {_removeMember}
    function _revokeRole(bytes32 role, address account) internal override {
        super._revokeRole(role, account);
        _removeMember(role, account);
    }

    /// @dev Grants `role` to `account`, and adds `account` to {roleMembers}
    ///      See {_addMember}
    function _setupRole(bytes32 role, address account) internal override {
        super._setupRole(role, account);
        _addMember(role, account);
    }

    /// @dev adds `account` to {roleMembers}, for `role`
    function _addMember(bytes32 role, address account) internal {
        uint256 idx = roleMembers[role].index;
        roleMembers[role].index += 1;

        roleMembers[role].members[idx] = account;
        roleMembers[role].indexOf[account] = idx;
    }

    /// @dev removes `account` from {roleMembers}, for `role`
    function _removeMember(bytes32 role, address account) internal {
        uint256 idx = roleMembers[role].indexOf[account];

        delete roleMembers[role].members[idx];
        delete roleMembers[role].indexOf[account];
    }
}
          

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

/// @author thirdweb

/**
 * @dev Provides a function to batch together multiple calls in a single external call.
 *
 * _Available since v4.1._
 */
interface IMulticall {
    /**
     * @dev Receives and executes a batch of function calls on this contract.
     */
    function multicall(bytes[] calldata data) external returns (bytes[] memory results);
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/draft-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;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    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");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}
          

// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.0;

/// @author thirdweb

import "./interface/IPermissions.sol";
import "../lib/TWStrings.sol";

/**
 *  @title   Permissions
 *  @dev     This contracts provides extending-contracts with role-based access control mechanisms
 */
contract Permissions is IPermissions {
    /// @dev Map from keccak256 hash of a role => a map from address => whether address has role.
    mapping(bytes32 => mapping(address => bool)) private _hasRole;

    /// @dev Map from keccak256 hash of a role to role admin. See {getRoleAdmin}.
    mapping(bytes32 => bytes32) private _getRoleAdmin;

    /// @dev Default admin role for all roles. Only accounts with this role can grant/revoke other roles.
    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /// @dev Modifier that checks if an account has the specified role; reverts otherwise.
    modifier onlyRole(bytes32 role) {
        _checkRole(role, msg.sender);
        _;
    }

    /**
     *  @notice         Checks whether an account has a particular role.
     *  @dev            Returns `true` if `account` has been granted `role`.
     *
     *  @param role     keccak256 hash of the role. e.g. keccak256("TRANSFER_ROLE")
     *  @param account  Address of the account for which the role is being checked.
     */
    function hasRole(bytes32 role, address account) public view override returns (bool) {
        return _hasRole[role][account];
    }

    /**
     *  @notice         Checks whether an account has a particular role;
     *                  role restrictions can be swtiched on and off.
     *
     *  @dev            Returns `true` if `account` has been granted `role`.
     *                  Role restrictions can be swtiched on and off:
     *                      - If address(0) has ROLE, then the ROLE restrictions
     *                        don't apply.
     *                      - If address(0) does not have ROLE, then the ROLE
     *                        restrictions will apply.
     *
     *  @param role     keccak256 hash of the role. e.g. keccak256("TRANSFER_ROLE")
     *  @param account  Address of the account for which the role is being checked.
     */
    function hasRoleWithSwitch(bytes32 role, address account) public view returns (bool) {
        if (!_hasRole[role][address(0)]) {
            return _hasRole[role][account];
        }

        return true;
    }

    /**
     *  @notice         Returns the admin role that controls the specified role.
     *  @dev            See {grantRole} and {revokeRole}.
     *                  To change a role's admin, use {_setRoleAdmin}.
     *
     *  @param role     keccak256 hash of the role. e.g. keccak256("TRANSFER_ROLE")
     */
    function getRoleAdmin(bytes32 role) external view override returns (bytes32) {
        return _getRoleAdmin[role];
    }

    /**
     *  @notice         Grants a role to an account, if not previously granted.
     *  @dev            Caller must have admin role for the `role`.
     *                  Emits {RoleGranted Event}.
     *
     *  @param role     keccak256 hash of the role. e.g. keccak256("TRANSFER_ROLE")
     *  @param account  Address of the account to which the role is being granted.
     */
    function grantRole(bytes32 role, address account) public virtual override {
        _checkRole(_getRoleAdmin[role], msg.sender);
        if (_hasRole[role][account]) {
            revert("Can only grant to non holders");
        }
        _setupRole(role, account);
    }

    /**
     *  @notice         Revokes role from an account.
     *  @dev            Caller must have admin role for the `role`.
     *                  Emits {RoleRevoked Event}.
     *
     *  @param role     keccak256 hash of the role. e.g. keccak256("TRANSFER_ROLE")
     *  @param account  Address of the account from which the role is being revoked.
     */
    function revokeRole(bytes32 role, address account) public virtual override {
        _checkRole(_getRoleAdmin[role], msg.sender);
        _revokeRole(role, account);
    }

    /**
     *  @notice         Revokes role from the account.
     *  @dev            Caller must have the `role`, with caller being the same as `account`.
     *                  Emits {RoleRevoked Event}.
     *
     *  @param role     keccak256 hash of the role. e.g. keccak256("TRANSFER_ROLE")
     *  @param account  Address of the account from which the role is being revoked.
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        if (msg.sender != account) {
            revert("Can only renounce for self");
        }
        _revokeRole(role, account);
    }

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

    /// @dev Sets up `role` for `account`
    function _setupRole(bytes32 role, address account) internal virtual {
        _hasRole[role][account] = true;
        emit RoleGranted(role, account, msg.sender);
    }

    /// @dev Revokes `role` from `account`
    function _revokeRole(bytes32 role, address account) internal virtual {
        _checkRole(role, account);
        delete _hasRole[role][account];
        emit RoleRevoked(role, account, msg.sender);
    }

    /// @dev Checks `role` for `account`. Reverts with a message including the required role.
    function _checkRole(bytes32 role, address account) internal view virtual {
        if (!_hasRole[role][account]) {
            revert(
                string(
                    abi.encodePacked(
                        "Permissions: account ",
                        TWStrings.toHexString(uint160(account), 20),
                        " is missing role ",
                        TWStrings.toHexString(uint256(role), 32)
                    )
                )
            );
        }
    }

    /// @dev Checks `role` for `account`. Reverts with a message including the required role.
    function _checkRoleWithSwitch(bytes32 role, address account) internal view virtual {
        if (!hasRoleWithSwitch(role, account)) {
            revert(
                string(
                    abi.encodePacked(
                        "Permissions: account ",
                        TWStrings.toHexString(uint160(account), 20),
                        " is missing role ",
                        TWStrings.toHexString(uint256(role), 32)
                    )
                )
            );
        }
    }
}
          

// SPDX-License-Identifier: Apache 2.0
pragma solidity ^0.8.0;

/// @author thirdweb

import "../lib/TWAddress.sol";
import "./interface/IMulticall.sol";

/**
 * @dev Provides a function to batch together multiple calls in a single external call.
 *
 * _Available since v4.1._
 */
contract Multicall is IMulticall {
    /**
     *  @notice Receives and executes a batch of function calls on this contract.
     *  @dev Receives and executes a batch of function calls on this contract.
     *
     *  @param data The bytes data that makes up the batch of function calls to execute.
     *  @return results The bytes data that makes up the result of the batch of function calls executed.
     */
    function multicall(bytes[] calldata data) external virtual override returns (bytes[] memory results) {
        results = new bytes[](data.length);
        for (uint256 i = 0; i < data.length; i++) {
            results[i] = TWAddress.functionDelegateCall(address(this), data[i]);
        }
        return results;
    }
}
          

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (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: Apache 2.0
pragma solidity ^0.8.0;

/// @author thirdweb

/**
 * @dev String operations.
 */
library TWStrings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @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] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}
          

// SPDX-License-Identifier: Apache 2.0
pragma solidity ^0.8.0;

/// @author thirdweb

/**
 * @dev Collection of functions related to the address type
 */
library TWAddress {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * [EIP1884](https://eips.ethereum.org/EIPS/eip-1884) increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}
          

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

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return 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);
        }
    }
}