Contract Source Code:

// SPDX-License-Identifier: MIT

pragma solidity 0.8.4;

import '@lbertenasco/contract-utils/contracts/utils/CollectableDust.sol';
import '@lbertenasco/contract-utils/contracts/utils/Governable.sol';
import '@lbertenasco/contract-utils/contracts/utils/Manageable.sol';
import '@openzeppelin/contracts/utils/structs/EnumerableSet.sol';
import '@openzeppelin/contracts/security/ReentrancyGuard.sol';

import './interfaces/IStealthVault.sol';

/*
 * YearnStealthVault
 */
contract StealthVault is Governable, Manageable, CollectableDust, ReentrancyGuard, IStealthVault {
  using EnumerableSet for EnumerableSet.AddressSet;

  uint256 public override gasBuffer = 69_420; // why not
  uint256 public override totalBonded;
  mapping(address => uint256) public override bonded;
  mapping(address => uint256) public override canUnbondAt;

  mapping(address => EnumerableSet.AddressSet) internal _callerStealthContracts;
  mapping(bytes32 => address) public override hashReportedBy;

  EnumerableSet.AddressSet internal _callers;

  constructor() Governable(msg.sender) Manageable(msg.sender) {}

  function isStealthVault() external pure override returns (bool) {
    return true;
  }

  function callers() external view override returns (address[] memory _callersList) {
    _callersList = new address[](_callers.length());
    for (uint256 i; i < _callers.length(); i++) {
      _callersList[i] = _callers.at(i);
    }
  }

  function callerContracts(address _caller) external view override returns (address[] memory _callerContractsList) {
    _callerContractsList = new address[](_callerStealthContracts[_caller].length());
    for (uint256 i; i < _callerStealthContracts[_caller].length(); i++) {
      _callerContractsList[i] = _callerStealthContracts[_caller].at(i);
    }
  }

  function caller(address _caller) external view override returns (bool _enabled) {
    return _callers.contains(_caller);
  }

  function callerStealthContract(address _caller, address _contract) external view override returns (bool _enabled) {
    return _callerStealthContracts[_caller].contains(_contract);
  }

  function bond() external payable override nonReentrant() {
    require(msg.value > 0, 'SV: bond more than zero');
    bonded[msg.sender] = bonded[msg.sender] + msg.value;
    totalBonded = totalBonded + msg.value;
    emit Bonded(msg.sender, msg.value, bonded[msg.sender]);
  }

  function unbondAll() external override {
    unbond(bonded[msg.sender]);
  }

  function startUnbond() public override nonReentrant() {
    canUnbondAt[msg.sender] = block.timestamp + 4 days;
  }

  function cancelUnbond() public override nonReentrant() {
    canUnbondAt[msg.sender] = 0;
  }

  function unbond(uint256 _amount) public override nonReentrant() {
    require(_amount > 0, 'SV: more than zero');
    require(_amount <= bonded[msg.sender], 'SV: amount too high');
    require(canUnbondAt[msg.sender] > 0, 'SV: not unbondind');
    require(block.timestamp > canUnbondAt[msg.sender], 'SV: unbond in cooldown');

    bonded[msg.sender] = bonded[msg.sender] - _amount;
    totalBonded = totalBonded - _amount;
    canUnbondAt[msg.sender] = 0;

    payable(msg.sender).transfer(_amount);
    emit Unbonded(msg.sender, _amount, bonded[msg.sender]);
  }

  function _penalize(
    address _caller,
    uint256 _penalty,
    address _reportedBy
  ) internal {
    bonded[_caller] = bonded[_caller] - _penalty;
    uint256 _amountReward = _penalty / 10;
    bonded[_reportedBy] = bonded[_reportedBy] + _amountReward;
    bonded[governor] = bonded[governor] + (_penalty - _amountReward);
  }

  modifier OnlyOneCallStack() {
    uint256 _gasLeftPlusBuffer = gasleft() + gasBuffer;
    require(_gasLeftPlusBuffer >= (block.gaslimit * 63) / 64, 'SV: eoa gas check failed');
    _;
  }

  // Hash
  function validateHash(
    address _caller,
    bytes32 _hash,
    uint256 _penalty
  ) external virtual override OnlyOneCallStack() nonReentrant() returns (bool _valid) {
    // Caller is required to be an EOA to avoid on-chain hash generation to bypass penalty.
    // solhint-disable-next-line avoid-tx-origin
    require(_caller == tx.origin, 'SV: not eoa');
    require(_callerStealthContracts[_caller].contains(msg.sender), 'SV: contract not enabled');
    require(bonded[_caller] >= _penalty, 'SV: not enough bonded');
    require(canUnbondAt[_caller] == 0, 'SV: unbonding');

    address reportedBy = hashReportedBy[_hash];
    if (reportedBy != address(0)) {
      // User reported this TX as public, locking penalty away
      _penalize(_caller, _penalty, reportedBy);

      emit PenaltyApplied(_hash, _caller, _penalty, reportedBy);

      // invalid: has was reported
      return false;
    }
    emit ValidatedHash(_hash, _caller, _penalty);
    // valid: hash was not reported
    return true;
  }

  function reportHash(bytes32 _hash) external override nonReentrant() {
    _reportHash(_hash);
  }

  function reportHashAndPay(bytes32 _hash) external payable override nonReentrant() {
    _reportHash(_hash);
    block.coinbase.transfer(msg.value);
  }

  function _reportHash(bytes32 _hash) internal {
    require(hashReportedBy[_hash] == address(0), 'SV: hash already reported');
    hashReportedBy[_hash] = msg.sender;
    emit ReportedHash(_hash, msg.sender);
  }

  // Caller Contracts
  function enableStealthContract(address _contract) external override nonReentrant() {
    _addCallerContract(_contract);
    emit StealthContractEnabled(msg.sender, _contract);
  }

  function enableStealthContracts(address[] calldata _contracts) external override nonReentrant() {
    for (uint256 i = 0; i < _contracts.length; i++) {
      _addCallerContract(_contracts[i]);
    }
    emit StealthContractsEnabled(msg.sender, _contracts);
  }

  function disableStealthContract(address _contract) external override nonReentrant() {
    _removeCallerContract(_contract);
    emit StealthContractDisabled(msg.sender, _contract);
  }

  function disableStealthContracts(address[] calldata _contracts) external override nonReentrant() {
    for (uint256 i = 0; i < _contracts.length; i++) {
      _removeCallerContract(_contracts[i]);
    }
    emit StealthContractsDisabled(msg.sender, _contracts);
  }

  function _addCallerContract(address _contract) internal {
    if (!_callers.contains(msg.sender)) _callers.add(msg.sender);
    require(_callerStealthContracts[msg.sender].add(_contract), 'SV: contract already added');
  }

  function _removeCallerContract(address _contract) internal {
    require(_callerStealthContracts[msg.sender].remove(_contract), 'SV: contract not found');
    if (_callerStealthContracts[msg.sender].length() == 0) _callers.remove(msg.sender);
  }

  // Manageable: restricted-access
  function setGasBuffer(uint256 _gasBuffer) external virtual override onlyManager {
    require(_gasBuffer < (block.gaslimit * 63) / 64, 'SV: gasBuffer too high');
    gasBuffer = _gasBuffer;
  }

  // Governable: restricted-access
  function transferGovernorBond(address _caller, uint256 _amount) external override onlyGovernor {
    bonded[governor] = bonded[governor] - _amount;
    bonded[_caller] = bonded[_caller] + _amount;
  }

  function transferBondToGovernor(address _caller, uint256 _amount) external override onlyGovernor {
    bonded[_caller] = bonded[_caller] - _amount;
    bonded[governor] = bonded[governor] + _amount;
  }

  // Manageable: setters
  function setPendingManager(address _pendingManager) external override onlyGovernor {
    _setPendingManager(_pendingManager);
  }

  function acceptManager() external override onlyPendingManager {
    _acceptManager();
  }

  // Governable: setters
  function setPendingGovernor(address _pendingGovernor) external override onlyGovernor {
    _setPendingGovernor(_pendingGovernor);
  }

  function acceptGovernor() external override onlyPendingGovernor {
    _acceptGovernor();
  }

  // Collectable Dust: restricted-access
  function sendDust(
    address _to,
    address _token,
    uint256 _amount
  ) external override onlyGovernor {
    _sendDust(_to, _token, _amount);
  }
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.4;

import '@openzeppelin/contracts/utils/structs/EnumerableSet.sol';
import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

import '../../interfaces/utils/ICollectableDust.sol';

abstract
contract CollectableDust is ICollectableDust {
  using SafeERC20 for IERC20;
  using EnumerableSet for EnumerableSet.AddressSet;

  address public constant ETH_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
  EnumerableSet.AddressSet internal protocolTokens;

  constructor() {}

  function _addProtocolToken(address _token) internal {
    require(!protocolTokens.contains(_token), 'collectable-dust/token-is-part-of-the-protocol');
    protocolTokens.add(_token);
  }

  function _removeProtocolToken(address _token) internal {
    require(protocolTokens.contains(_token), 'collectable-dust/token-not-part-of-the-protocol');
    protocolTokens.remove(_token);
  }

  function _sendDust(
    address _to,
    address _token,
    uint256 _amount
  ) internal {
    require(_to != address(0), 'collectable-dust/cant-send-dust-to-zero-address');
    require(!protocolTokens.contains(_token), 'collectable-dust/token-is-part-of-the-protocol');
    if (_token == ETH_ADDRESS) {
      payable(_to).transfer(_amount);
    } else {
      IERC20(_token).safeTransfer(_to, _amount);
    }
    emit DustSent(_to, _token, _amount);
  }
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.4;

import '../../interfaces/utils/IGovernable.sol';

abstract
contract Governable is IGovernable {
  address public override governor;
  address public override pendingGovernor;

  constructor(address _governor) {
    require(_governor != address(0), 'governable/governor-should-not-be-zero-address');
    governor = _governor;
  }

  function _setPendingGovernor(address _pendingGovernor) internal {
    require(_pendingGovernor != address(0), 'governable/pending-governor-should-not-be-zero-addres');
    pendingGovernor = _pendingGovernor;
    emit PendingGovernorSet(_pendingGovernor);
  }

  function _acceptGovernor() internal {
    governor = pendingGovernor;
    pendingGovernor = address(0);
    emit GovernorAccepted();
  }

  function isGovernor(address _account) public view override returns (bool _isGovernor) {
    return _account == governor;
  }

  modifier onlyGovernor {
    require(isGovernor(msg.sender), 'governable/only-governor');
    _;
  }

  modifier onlyPendingGovernor {
    require(msg.sender == pendingGovernor, 'governable/only-pending-governor');
    _;
  }
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.4;

import '../../interfaces/utils/IManageable.sol';

abstract
contract Manageable is IManageable {
  address public override manager;
  address public override pendingManager;

  constructor(address _manager) {
    require(_manager != address(0), 'manageable/manager-should-not-be-zero-address');
    manager = _manager;
  }

  function _setPendingManager(address _pendingManager) internal {
    require(_pendingManager != address(0), 'manageable/pending-manager-should-not-be-zero-addres');
    pendingManager = _pendingManager;
    emit PendingManagerSet(_pendingManager);
  }

  function _acceptManager() internal {
    manager = pendingManager;
    pendingManager = address(0);
    emit ManagerAccepted();
  }

  function isManager(address _account) public view override returns (bool _isManager) {
    return _account == manager;
  }

  modifier onlyManager {
    require(isManager(msg.sender), 'manageable/only-manager');
    _;
  }

  modifier onlyPendingManager {
    require(msg.sender == pendingManager, 'manageable/only-pending-manager');
    _;
  }
}

// SPDX-License-Identifier: MIT

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.
 *
 * ```
 * 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.
 */
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;

            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.

            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) {
        require(set._values.length > index, "EnumerableSet: index out of bounds");
        return set._values[index];
    }

    // 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);
    }

    // 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))));
    }


    // 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 on 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));
    }
}

// SPDX-License-Identifier: MIT

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 make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

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

        _;

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

// SPDX-License-Identifier: MIT
pragma solidity 0.8.4;

interface IStealthVault {
  //events
  event Bonded(address indexed _caller, uint256 _amount, uint256 _finalBond);
  event Unbonded(address indexed _caller, uint256 _amount, uint256 _finalBond);
  event ReportedHash(bytes32 _hash, address _reportedBy);
  event PenaltyApplied(bytes32 _hash, address _caller, uint256 _penalty, address _reportedBy);
  event ValidatedHash(bytes32 _hash, address _caller, uint256 _penalty);

  event StealthContractEnabled(address indexed _caller, address _contract);

  event StealthContractsEnabled(address indexed _caller, address[] _contracts);

  event StealthContractDisabled(address indexed _caller, address _contract);

  event StealthContractsDisabled(address indexed _caller, address[] _contracts);

  function isStealthVault() external pure returns (bool);

  // getters
  function callers() external view returns (address[] memory _callers);

  function callerContracts(address _caller) external view returns (address[] memory _contracts);

  // global bond
  function gasBuffer() external view returns (uint256 _gasBuffer);

  function totalBonded() external view returns (uint256 _totalBonded);

  function bonded(address _caller) external view returns (uint256 _bond);

  function canUnbondAt(address _caller) external view returns (uint256 _canUnbondAt);

  // global caller
  function caller(address _caller) external view returns (bool _enabled);

  function callerStealthContract(address _caller, address _contract) external view returns (bool _enabled);

  // global hash
  function hashReportedBy(bytes32 _hash) external view returns (address _reportedBy);

  // governor
  function setGasBuffer(uint256 _gasBuffer) external;

  function transferGovernorBond(address _caller, uint256 _amount) external;

  function transferBondToGovernor(address _caller, uint256 _amount) external;

  // caller
  function bond() external payable;

  function startUnbond() external;

  function cancelUnbond() external;

  function unbondAll() external;

  function unbond(uint256 _amount) external;

  function enableStealthContract(address _contract) external;

  function enableStealthContracts(address[] calldata _contracts) external;

  function disableStealthContract(address _contract) external;

  function disableStealthContracts(address[] calldata _contracts) external;

  // stealth-contract
  function validateHash(
    address _caller,
    bytes32 _hash,
    uint256 _penalty
  ) external returns (bool);

  // watcher
  function reportHash(bytes32 _hash) external;

  function reportHashAndPay(bytes32 _hash) external payable;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

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

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

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

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

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

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.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'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

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

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

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// SPDX-License-Identifier: MIT
pragma solidity 0.8.4;

interface ICollectableDust {
  event DustSent(address _to, address token, uint256 amount);

  function sendDust(address _to, address _token, uint256 _amount) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

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

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private 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

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT
pragma solidity 0.8.4;

interface IGovernable {
  event PendingGovernorSet(address pendingGovernor);
  event GovernorAccepted();

  function setPendingGovernor(address _pendingGovernor) external;
  function acceptGovernor() external;

  function governor() external view returns (address _governor);
  function pendingGovernor() external view returns (address _pendingGovernor);

  function isGovernor(address _account) external view returns (bool _isGovernor);
}

// SPDX-License-Identifier: MIT
pragma solidity 0.8.4;

interface IManageable {
  event PendingManagerSet(address pendingManager);
  event ManagerAccepted();

  function setPendingManager(address _pendingManager) external;
  function acceptManager() external;

  function manager() external view returns (address _manager);
  function pendingManager() external view returns (address _pendingManager);

  function isManager(address _account) external view returns (bool _isManager);
}