contract IVTProxy is UpgradeabilityProxy, Pausable {

  /**
   * @dev Storage slot with the perm of the contract.
   * This is the keccak-256 hash of "www.invault.io.proxy.permission", and is
   * validated in the constructor.
   */
  bytes32 private constant PERM_SLOT = 0x9f2b05956adf3f5dc678f8c50dd9693f2163f4bec0d0b84a13327b894102a4e5;

  /**
   * @dev Modifier to check whether the `msg.sender` is the Permission.
   * If it is, it will run the function.
   */
  modifier OnlyPermission() {
    require(msg.sender == _perm());
      _;
  }

  /**
   * Contract constructor.
   * @param _implementation address of the initial implementation.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  constructor(address _implementation, address _permission) UpgradeabilityProxy(_implementation) public {
    assert(PERM_SLOT == keccak256("www.invault.io.proxy.permission"));
    _setPermission(_permission);
  }

  /**
   * @return The address of the proxy admin.
   */
  function getPermAddress() external view whenNotPaused returns (address) {
    return _perm();
  }

  /**
   * @return The address of the implementation.
   */
  function getImplAddress() external view whenNotPaused returns (address) {
    return _implementation();
  }

  /**
   * @dev 升级proxy中的implementation，只有Permission可以调用
   * @param newImplementation Address of the new implementation.
   */
  function upgradeImpl(address newImplementation) external OnlyPermission whenNotPaused returns(bool) {
    _upgradeTo(newImplementation);
    return true;
  }



  /**
   * @dev 升级proxy中的permission，只有Permission可以调用
   * @param newPermission Address.
   */
  function upgradePerm(address newPermission) external OnlyPermission whenNotPaused returns(bool)  {
    _setPermission(newPermission);
    return true;
  }


/**
 * @dev 请求升级
 * @param _data call
 * @return {[type]}
 */
  function requestUpgrade(bytes calldata _data) external onlyOwner whenNotPaused {
     address permission = _perm();
     permission.call(_data);

  }

  /**
   * @return The permission slot.
   */
  function _perm() internal view returns (address adm) {
    bytes32 slot = PERM_SLOT;
    assembly {
      adm := sload(slot)
    }
  }

  /**
   * @dev Sets the address of the proxy permission.
   * @param newPerm Address of the new proxy permission.
   */
  function _setPermission(address newPerm) internal {

    require(AddressUtils.isContract(newPerm), "Cannot set a proxy permission to a non-contract address");

    bytes32 slot = PERM_SLOT;

    assembly {
      sstore(slot, newPerm)
    }
  }

}
/**
 * @title IVTProxy
 * @dev Contract for Proxy applications.
 */
function getPermAddress() external view whenNotPaused returns (address) {
    return _perm();
  }
/**
 * @return The address of the proxy admin.
 */