// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

/* Interface Imports */
import {IL1StandardBridge} from './IL1StandardBridge.sol';
import {IL1ERC20Bridge} from './IL1ERC20Bridge.sol';
import {IL2ERC20Bridge} from '../../L2/messaging/IL2ERC20Bridge.sol';
import {IERC20} from '@openzeppelin/contracts/token/ERC20/IERC20.sol';

/* Library Imports */
import {CrossDomainEnabled} from '../../libraries/bridge/CrossDomainEnabled.sol';
import {Lib_PredeployAddresses} from '../../libraries/constants/Lib_PredeployAddresses.sol';
import {Address} from '@openzeppelin/contracts/utils/Address.sol';
import {SafeERC20} from '@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol';

/**
 * @title L1StandardBridge
 * @dev The L1 ETH and ERC20 Bridge is a contract which stores deposited L1 funds and standard
 * tokens that are in use on L2. It synchronizes a corresponding L2 Bridge, informing it of deposits
 * and listening to it for newly finalized withdrawals.
 *
 * Runtime target: EVM
 */
contract L1StandardBridge is IL1StandardBridge, CrossDomainEnabled {
  using SafeERC20 for IERC20;

  /********************************
   * External Contract References *
   ********************************/

  address public l2TokenBridge;

  // Maps L1 token to L2 token to balance of the L1 token deposited
  mapping(address => mapping(address => uint256)) public deposits;

  bytes32 public priorDepositInfoHash;
  bytes32 public currentDepositInfoHash;
  uint256 public lastHashUpdateBlock;

  /***************
   * Constructor *
   ***************/

  // This contract lives behind a proxy, so the constructor parameters will go unused.
  constructor() CrossDomainEnabled(address(0)) {}

  /******************
   * Initialization *
   ******************/

  /**
   * @param _l1messenger L1 Messenger address being used for cross-chain communications.
   * @param _l2TokenBridge L2 standard bridge address.
   */
  function initialize(address _l1messenger, address _l2TokenBridge) public {
    require(messenger == address(0), 'Contract has already been initialized.');
    messenger = _l1messenger;
    l2TokenBridge = _l2TokenBridge;
  }

  /**************
   * Depositing *
   **************/

  /** @dev Modifier requiring sender to be EOA.  This check could be bypassed by a malicious
   *  contract via initcode, but it takes care of the user error we want to avoid.
   */
  modifier onlyEOA() {
    // Used to stop deposits from contracts (avoid accidentally lost tokens)
    require(!Address.isContract(msg.sender), 'Account not EOA');
    _;
  }

  /**
   * @dev This function can be called with no data
   * to deposit an amount of ETH to the caller's balance on L2.
   * Since the receive function doesn't take data, a conservative
   * default amount is forwarded to L2.
   */
  receive() external payable onlyEOA {
    _initiateETHDeposit(msg.sender, msg.sender, 1_300_000, bytes(''));
  }

  /**
   * @inheritdoc IL1StandardBridge
   */
  function depositETH(uint32 _l2Gas, bytes calldata _data)
    external
    payable
    onlyEOA
  {
    _initiateETHDeposit(msg.sender, msg.sender, _l2Gas, _data);
  }

  /**
   * @inheritdoc IL1StandardBridge
   */
  function depositETHTo(
    address _to,
    uint32 _l2Gas,
    bytes calldata _data
  ) external payable {
    _initiateETHDeposit(msg.sender, _to, _l2Gas, _data);
  }

  /**
   * @dev Performs the logic for deposits by storing the ETH and informing the L2 ETH Gateway of
   * the deposit.
   * @param _from Account to pull the deposit from on L1.
   * @param _to Account to give the deposit to on L2.
   * @param _l2Gas Gas limit required to complete the deposit on L2.
   * @param _data Optional data to forward to L2. This data is provided
   *        solely as a convenience for external contracts. Aside from enforcing a maximum
   *        length, these contracts provide no guarantees about its content.
   */
  function _initiateETHDeposit(
    address _from,
    address _to,
    uint32 _l2Gas,
    bytes memory _data
  ) internal {
    // Construct calldata for finalizeDeposit call
    bytes memory message = abi.encodeWithSelector(
      IL2ERC20Bridge.finalizeDeposit.selector,
      address(0),
      Lib_PredeployAddresses.OVM_ETH,
      _from,
      _to,
      msg.value,
      _data
    );

    // Send calldata into L2
    sendCrossDomainMessage(l2TokenBridge, _l2Gas, message);

    // compute and update deposit hash
    _updateDepositHash(
      address(0),
      Lib_PredeployAddresses.OVM_ETH,
      _from,
      _to,
      msg.value
    );

    emit ETHDepositInitiated(_from, _to, msg.value, _data);
  }

  /**
   * @inheritdoc IL1ERC20Bridge
   */
  function depositERC20(
    address _l1Token,
    address _l2Token,
    uint256 _amount,
    uint32 _l2Gas,
    bytes calldata _data
  ) external virtual onlyEOA {
    _initiateERC20Deposit(
      _l1Token,
      _l2Token,
      msg.sender,
      msg.sender,
      _amount,
      _l2Gas,
      _data
    );
  }

  /**
   * @inheritdoc IL1ERC20Bridge
   */
  function depositERC20To(
    address _l1Token,
    address _l2Token,
    address _to,
    uint256 _amount,
    uint32 _l2Gas,
    bytes calldata _data
  ) external virtual {
    _initiateERC20Deposit(
      _l1Token,
      _l2Token,
      msg.sender,
      _to,
      _amount,
      _l2Gas,
      _data
    );
  }

  /**
   * @dev Performs the logic for deposits by informing the L2 Deposited Token
   * contract of the deposit and calling a handler to lock the L1 funds. (e.g. transferFrom)
   *
   * @param _l1Token Address of the L1 ERC20 we are depositing
   * @param _l2Token Address of the L1 respective L2 ERC20
   * @param _from Account to pull the deposit from on L1
   * @param _to Account to give the deposit to on L2
   * @param _amount Amount of the ERC20 to deposit.
   * @param _l2Gas Gas limit required to complete the deposit on L2.
   * @param _data Optional data to forward to L2. This data is provided
   *        solely as a convenience for external contracts. Aside from enforcing a maximum
   *        length, these contracts provide no guarantees about its content.
   */
  function _initiateERC20Deposit(
    address _l1Token,
    address _l2Token,
    address _from,
    address _to,
    uint256 _amount,
    uint32 _l2Gas,
    bytes calldata _data
  ) internal {
    // When a deposit is initiated on L1, the L1 Bridge transfers the funds to itself for future
    // withdrawals. safeTransferFrom also checks if the contract has code, so this will fail if
    // _from is an EOA or address(0).
    IERC20(_l1Token).safeTransferFrom(_from, address(this), _amount);

    // Construct calldata for _l2Token.finalizeDeposit(_to, _amount)
    bytes memory message = abi.encodeWithSelector(
      IL2ERC20Bridge.finalizeDeposit.selector,
      _l1Token,
      _l2Token,
      _from,
      _to,
      _amount,
      _data
    );

    // Send calldata into L2
    sendCrossDomainMessage(l2TokenBridge, _l2Gas, message);

    deposits[_l1Token][_l2Token] = deposits[_l1Token][_l2Token] + _amount;

    _updateDepositHash(_l1Token, _l2Token, _from, _to, _amount);

    emit ERC20DepositInitiated(_l1Token, _l2Token, _from, _to, _amount, _data);
  }

  function _updateDepositHash(
    address _l1Token,
    address _l2Token,
    address _from,
    address _to,
    uint256 _amount
  ) internal {
    // if block number is different only then update prior
    if (block.number > lastHashUpdateBlock) {
      priorDepositInfoHash = currentDepositInfoHash;
    }
    currentDepositInfoHash = keccak256(
      abi.encode(
        currentDepositInfoHash,
        _l1Token,
        _l2Token,
        _from,
        _to,
        _amount
      )
    );

    lastHashUpdateBlock = block.number;
  }

  /*************************
   * Cross-chain Functions *
   *************************/

  /**
   * @inheritdoc IL1StandardBridge
   */
  function finalizeETHWithdrawal(
    address _from,
    address _to,
    uint256 _amount,
    bytes calldata _data
  ) external onlyFromCrossDomainAccount(l2TokenBridge) {
    (bool success, ) = _to.call{value: _amount}(new bytes(0));
    require(success, 'TransferHelper::safeTransferETH: ETH transfer failed');

    emit ETHWithdrawalFinalized(_from, _to, _amount, _data);
  }

  /**
   * @inheritdoc IL1ERC20Bridge
   */
  function finalizeERC20Withdrawal(
    address _l1Token,
    address _l2Token,
    address _from,
    address _to,
    uint256 _amount,
    bytes calldata _data
  ) external onlyFromCrossDomainAccount(l2TokenBridge) {
    deposits[_l1Token][_l2Token] = deposits[_l1Token][_l2Token] - _amount;

    // When a withdrawal is finalized on L1, the L1 Bridge transfers the funds to the withdrawer
    IERC20(_l1Token).safeTransfer(_to, _amount);

    emit ERC20WithdrawalFinalized(
      _l1Token,
      _l2Token,
      _from,
      _to,
      _amount,
      _data
    );
  }

  /*****************************
   * Temporary - Migrating ETH *
   *****************************/

  /**
   * @dev Adds ETH balance to the account. This is meant to allow for ETH
   * to be migrated from an old gateway to a new gateway.
   * NOTE: This is left for one upgrade only so we are able to receive the migrated ETH from the
   * old contract
   */
  function donateETH() external payable {}
}

// SPDX-License-Identifier: MIT
pragma solidity >0.5.0 <0.9.0;

import './IL1ERC20Bridge.sol';

/**
 * @title IL1StandardBridge
 */
interface IL1StandardBridge is IL1ERC20Bridge {
  /**********
   * Events *
   **********/
  event ETHDepositInitiated(
    address indexed _from,
    address indexed _to,
    uint256 _amount,
    bytes _data
  );

  event ETHWithdrawalFinalized(
    address indexed _from,
    address indexed _to,
    uint256 _amount,
    bytes _data
  );

  /********************
   * Public Functions *
   ********************/

  /**
   * @dev Deposit an amount of the ETH to the caller's balance on L2.
   * @param _l2Gas Gas limit required to complete the deposit on L2.
   * @param _data Optional data to forward to L2. This data is provided
   *        solely as a convenience for external contracts. Aside from enforcing a maximum
   *        length, these contracts provide no guarantees about its content.
   */
  function depositETH(uint32 _l2Gas, bytes calldata _data) external payable;

  /**
   * @dev Deposit an amount of ETH to a recipient's balance on L2.
   * @param _to L2 address to credit the withdrawal to.
   * @param _l2Gas Gas limit required to complete the deposit on L2.
   * @param _data Optional data to forward to L2. This data is provided
   *        solely as a convenience for external contracts. Aside from enforcing a maximum
   *        length, these contracts provide no guarantees about its content.
   */
  function depositETHTo(
    address _to,
    uint32 _l2Gas,
    bytes calldata _data
  ) external payable;

  /*************************
   * Cross-chain Functions *
   *************************/

  /**
   * @dev Complete a withdrawal from L2 to L1, and credit funds to the recipient's balance of the
   * L1 ETH token. Since only the xDomainMessenger can call this function, it will never be called
   * before the withdrawal is finalized.
   * @param _from L2 address initiating the transfer.
   * @param _to L1 address to credit the withdrawal to.
   * @param _amount Amount of the ERC20 to deposit.
   * @param _data Optional data to forward to L2. This data is provided
   *        solely as a convenience for external contracts. Aside from enforcing a maximum
   *        length, these contracts provide no guarantees about its content.
   */
  function finalizeETHWithdrawal(
    address _from,
    address _to,
    uint256 _amount,
    bytes calldata _data
  ) external;
}

// SPDX-License-Identifier: MIT
pragma solidity >0.5.0 <0.9.0;

/**
 * @title IL1ERC20Bridge
 */
interface IL1ERC20Bridge {
  /**********
   * Events *
   **********/

  event ERC20DepositInitiated(
    address indexed _l1Token,
    address indexed _l2Token,
    address indexed _from,
    address _to,
    uint256 _amount,
    bytes _data
  );

  event ERC20WithdrawalFinalized(
    address indexed _l1Token,
    address indexed _l2Token,
    address indexed _from,
    address _to,
    uint256 _amount,
    bytes _data
  );

  /********************
   * Public Functions *
   ********************/

  /**
   * @dev get the address of the corresponding L2 bridge contract.
   * @return Address of the corresponding L2 bridge contract.
   */
  function l2TokenBridge() external returns (address);

  /**
   * @dev deposit an amount of the ERC20 to the caller's balance on L2.
   * @param _l1Token Address of the L1 ERC20 we are depositing
   * @param _l2Token Address of the L1 respective L2 ERC20
   * @param _amount Amount of the ERC20 to deposit
   * @param _l2Gas Gas limit required to complete the deposit on L2.
   * @param _data Optional data to forward to L2. This data is provided
   *        solely as a convenience for external contracts. Aside from enforcing a maximum
   *        length, these contracts provide no guarantees about its content.
   */
  function depositERC20(
    address _l1Token,
    address _l2Token,
    uint256 _amount,
    uint32 _l2Gas,
    bytes calldata _data
  ) external;

  /**
   * @dev deposit an amount of ERC20 to a recipient's balance on L2.
   * @param _l1Token Address of the L1 ERC20 we are depositing
   * @param _l2Token Address of the L1 respective L2 ERC20
   * @param _to L2 address to credit the withdrawal to.
   * @param _amount Amount of the ERC20 to deposit.
   * @param _l2Gas Gas limit required to complete the deposit on L2.
   * @param _data Optional data to forward to L2. This data is provided
   *        solely as a convenience for external contracts. Aside from enforcing a maximum
   *        length, these contracts provide no guarantees about its content.
   */
  function depositERC20To(
    address _l1Token,
    address _l2Token,
    address _to,
    uint256 _amount,
    uint32 _l2Gas,
    bytes calldata _data
  ) external;

  /*************************
   * Cross-chain Functions *
   *************************/

  /**
   * @dev Complete a withdrawal from L2 to L1, and credit funds to the recipient's balance of the
   * L1 ERC20 token.
   * This call will fail if the initialized withdrawal from L2 has not been finalized.
   *
   * @param _l1Token Address of L1 token to finalizeWithdrawal for.
   * @param _l2Token Address of L2 token where withdrawal was initiated.
   * @param _from L2 address initiating the transfer.
   * @param _to L1 address to credit the withdrawal to.
   * @param _amount Amount of the ERC20 to deposit.
   * @param _data Data provided by the sender on L2. This data is provided
   *   solely as a convenience for external contracts. Aside from enforcing a maximum
   *   length, these contracts provide no guarantees about its content.
   */
  function finalizeERC20Withdrawal(
    address _l1Token,
    address _l2Token,
    address _from,
    address _to,
    uint256 _amount,
    bytes calldata _data
  ) external;
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

/**
 * @title IL2ERC20Bridge
 */
interface IL2ERC20Bridge {
  /**********
   * Events *
   **********/

  event WithdrawalInitiated(
    address indexed _l1Token,
    address indexed _l2Token,
    address indexed _from,
    address _to,
    uint256 _amount,
    bytes _data
  );

  event DepositFinalized(
    address indexed _l1Token,
    address indexed _l2Token,
    address indexed _from,
    address _to,
    uint256 _amount,
    bytes _data
  );

  event DepositFailed(
    address indexed _l1Token,
    address indexed _l2Token,
    address indexed _from,
    address _to,
    uint256 _amount,
    bytes _data
  );

  /********************
   * Public Functions *
   ********************/

  /**
   * @dev get the address of the corresponding L1 bridge contract.
   * @return Address of the corresponding L1 bridge contract.
   */
  function l1TokenBridge() external returns (address);

  /**
   * @dev initiate a withdraw of some tokens to the caller's account on L1
   * @param _l2Token Address of L2 token where withdrawal was initiated.
   * @param _amount Amount of the token to withdraw.
   * param _l1Gas Unused, but included for potential forward compatibility considerations.
   * @param _data Optional data to forward to L1. This data is provided
   *        solely as a convenience for external contracts. Aside from enforcing a maximum
   *        length, these contracts provide no guarantees about its content.
   */
  function withdraw(
    address _l2Token,
    uint256 _amount,
    uint32 _l1Gas,
    bytes calldata _data
  ) external;

  /**
   * @dev initiate a withdraw of some token to a recipient's account on L1.
   * @param _l2Token Address of L2 token where withdrawal is initiated.
   * @param _to L1 adress to credit the withdrawal to.
   * @param _amount Amount of the token to withdraw.
   * param _l1Gas Unused, but included for potential forward compatibility considerations.
   * @param _data Optional data to forward to L1. This data is provided
   *        solely as a convenience for external contracts. Aside from enforcing a maximum
   *        length, these contracts provide no guarantees about its content.
   */
  function withdrawTo(
    address _l2Token,
    address _to,
    uint256 _amount,
    uint32 _l1Gas,
    bytes calldata _data
  ) external;

  /*************************
   * Cross-chain Functions *
   *************************/

  /**
   * @dev Complete a deposit from L1 to L2, and credits funds to the recipient's balance of this
   * L2 token. This call will fail if it did not originate from a corresponding deposit in
   * L1StandardTokenBridge.
   * @param _l1Token Address for the l1 token this is called with
   * @param _l2Token Address for the l2 token this is called with
   * @param _from Account to pull the deposit from on L2.
   * @param _to Address to receive the withdrawal at
   * @param _amount Amount of the token to withdraw
   * @param _data Data provider by the sender on L1. This data is provided
   *        solely as a convenience for external contracts. Aside from enforcing a maximum
   *        length, these contracts provide no guarantees about its content.
   */
  function finalizeDeposit(
    address _l1Token,
    address _l2Token,
    address _from,
    address _to,
    uint256 _amount,
    bytes calldata _data
  ) external;
}

// 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 >0.5.0 <0.9.0;

/* Interface Imports */
import {ICrossDomainMessenger} from './ICrossDomainMessenger.sol';

/**
 * @title CrossDomainEnabled
 * @dev Helper contract for contracts performing cross-domain communications
 *
 * Compiler used: defined by inheriting contract
 * Runtime target: defined by inheriting contract
 */
contract CrossDomainEnabled {
  /*************
   * Variables *
   *************/

  // Messenger contract used to send and recieve messages from the other domain.
  address public messenger;

  /***************
   * Constructor *
   ***************/

  /**
   * @param _messenger Address of the CrossDomainMessenger on the current layer.
   */
  constructor(address _messenger) {
    messenger = _messenger;
  }

  /**********************
   * Function Modifiers *
   **********************/

  /**
   * Enforces that the modified function is only callable by a specific cross-domain account.
   * @param _sourceDomainAccount The only account on the originating domain which is
   *  authenticated to call this function.
   */
  modifier onlyFromCrossDomainAccount(address _sourceDomainAccount) {
    require(
      msg.sender == address(getCrossDomainMessenger()),
      'OVM_XCHAIN: messenger contract unauthenticated'
    );

    require(
      getCrossDomainMessenger().xDomainMessageSender() == _sourceDomainAccount,
      'OVM_XCHAIN: wrong sender of cross-domain message'
    );

    _;
  }

  /**********************
   * Internal Functions *
   **********************/

  /**
   * Gets the messenger, usually from storage. This function is exposed in case a child contract
   * needs to override.
   * @return The address of the cross-domain messenger contract which should be used.
   */
  function getCrossDomainMessenger()
    internal
    virtual
    returns (ICrossDomainMessenger)
  {
    return ICrossDomainMessenger(messenger);
  }

  /**q
   * Sends a message to an account on another domain
   * @param _crossDomainTarget The intended recipient on the destination domain
   * @param _message The data to send to the target (usually calldata to a function with
   *  `onlyFromCrossDomainAccount()`)
   * @param _gasLimit The gasLimit for the receipt of the message on the target domain.
   */
  function sendCrossDomainMessage(
    address _crossDomainTarget,
    uint32 _gasLimit,
    bytes memory _message
  ) internal {
    getCrossDomainMessenger().sendMessage(
      _crossDomainTarget,
      _message,
      _gasLimit
    );
  }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

/**
 * @title Lib_PredeployAddresses
 */
library Lib_PredeployAddresses {
  // solhint-disable max-line-length
  address internal constant L2_TO_L1_MESSAGE_PASSER =
    0x4200000000000000000000000000000000000000;
  address internal constant L1_MESSAGE_SENDER =
    0x4200000000000000000000000000000000000001;
  address internal constant DEPLOYER_WHITELIST =
    0x4200000000000000000000000000000000000002;
  address payable internal constant OVM_ETH =
    payable(0x4200000000000000000000000000000000000006);
  // solhint-disable-next-line max-line-length
  address internal constant L2_CROSS_DOMAIN_MESSENGER =
    0x4200000000000000000000000000000000000007;
  address internal constant LIB_ADDRESS_MANAGER =
    0x4200000000000000000000000000000000000008;
  address internal constant PROXY_EOA =
    0x4200000000000000000000000000000000000009;
  address internal constant L2_STANDARD_BRIDGE =
    0x4200000000000000000000000000000000000010;
  address internal constant SEQUENCER_FEE_WALLET =
    0x4200000000000000000000000000000000000011;
  address internal constant L2_STANDARD_TOKEN_FACTORY =
    0x4200000000000000000000000000000000000012;
  address internal constant L1_BLOCK_NUMBER =
    0x4200000000000000000000000000000000000013;
  address internal constant OVM_GAS_PRICE_ORACLE =
    0x420000000000000000000000000000000000000F;
  address internal constant PROXY__BOBA_TURING_PREPAY =
    0x4200000000000000000000000000000000000020;
  address internal constant BOBA_TURING_PREPAY =
    0x4200000000000000000000000000000000000021;
  address internal constant BOBA_TURING_HELPER =
    0x4200000000000000000000000000000000000022;
}

// 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;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

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

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

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

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

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

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

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

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

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

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

    /**
     * @dev 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

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'
        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
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// SPDX-License-Identifier: MIT
pragma solidity >0.5.0 <0.9.0;

/**
 * @title ICrossDomainMessenger
 */
interface ICrossDomainMessenger {
  /**********
   * Events *
   **********/

  event SentMessage(
    address indexed target,
    address sender,
    bytes message,
    uint256 messageNonce,
    uint256 gasLimit
  );
  event RelayedMessage(bytes32 indexed msgHash);
  event FailedRelayedMessage(bytes32 indexed msgHash);

  /*************
   * Variables *
   *************/

  function xDomainMessageSender() external view returns (address);

  /********************
   * Public Functions *
   ********************/

  /**
   * Sends a cross domain message to the target messenger.
   * @param _target Target contract address.
   * @param _message Message to send to the target.
   * @param _gasLimit Gas limit for the provided message.
   */
  function sendMessage(
    address _target,
    bytes calldata _message,
    uint32 _gasLimit
  ) external;
}
{"success": true, "error": null, "results": {}}