// File: @openzeppelin/contracts/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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);
}

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./IERC20.sol";
import "../../math/SafeMath.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 SafeMath for uint256;
    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).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _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");
        }
    }
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <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);
            }
        }
    }
}

// File: contracts/optimistic-ethereum/OVM/bridge/tokens/OVM_L1StandardBridge.sol



// SPDX-License-Identifier: MIT
// @unsupported: ovm
pragma solidity >0.5.0 <0.8.0;
pragma experimental ABIEncoderV2;

/* Interface Imports */
import { iOVM_L1StandardBridge } from "../../../iOVM/bridge/tokens/iOVM_L1StandardBridge.sol";
import { iOVM_L1ERC20Bridge } from "../../../iOVM/bridge/tokens/iOVM_L1ERC20Bridge.sol";
import { iOVM_L2ERC20Bridge } from "../../../iOVM/bridge/tokens/iOVM_L2ERC20Bridge.sol";
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/* Library Imports */
import { OVM_CrossDomainEnabled } from "../../../libraries/bridge/OVM_CrossDomainEnabled.sol";
import { Lib_PredeployAddresses } from "../../../libraries/constants/Lib_PredeployAddresses.sol";
import { SafeMath } from "@openzeppelin/contracts/math/SafeMath.sol";
import { Address } from "@openzeppelin/contracts/utils/Address.sol";
import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";

/**
 * @title OVM_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.
 *
 * Compiler used: solc
 * Runtime target: EVM
 */
contract OVM_L1StandardBridge is iOVM_L1StandardBridge, OVM_CrossDomainEnabled {
    using SafeMath for uint;
    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;

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

    // This contract lives behind a proxy, so the constructor parameters will go unused.
    constructor()
        OVM_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 iOVM_L1StandardBridge
     */
    function depositETH(
        uint32 _l2Gas,
        bytes calldata _data
    )
        external
        override
        payable
        onlyEOA()
    {
        _initiateETHDeposit(
            msg.sender,
            msg.sender,
            _l2Gas,
            _data
        );
    }

    /**
     * @inheritdoc iOVM_L1StandardBridge
     */
    function depositETHTo(
        address _to,
        uint32 _l2Gas,
        bytes calldata _data
    )
        external
        override
        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(
                iOVM_L2ERC20Bridge.finalizeDeposit.selector,
                address(0),
                Lib_PredeployAddresses.OVM_ETH,
                _from,
                _to,
                msg.value,
                _data
            );

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

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

    /**
     * @inheritdoc iOVM_L1ERC20Bridge
     */
    function depositERC20(
        address _l1Token,
        address _l2Token,
        uint256 _amount,
        uint32 _l2Gas,
        bytes calldata _data
    )
        external
        override
        virtual
        onlyEOA()
    {
        _initiateERC20Deposit(_l1Token, _l2Token, msg.sender, msg.sender, _amount, _l2Gas, _data);
    }

     /**
     * @inheritdoc iOVM_L1ERC20Bridge
     */
    function depositERC20To(
        address _l1Token,
        address _l2Token,
        address _to,
        uint256 _amount,
        uint32 _l2Gas,
        bytes calldata _data
    )
        external
        override
        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(
            iOVM_L2ERC20Bridge.finalizeDeposit.selector,
            _l1Token,
            _l2Token,
            _from,
            _to,
            _amount,
            _data
        );

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

        deposits[_l1Token][_l2Token] = deposits[_l1Token][_l2Token].add(_amount);

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

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

     /**
     * @inheritdoc iOVM_L1StandardBridge
     */
    function finalizeETHWithdrawal(
        address _from,
        address _to,
        uint256 _amount,
        bytes calldata _data
    )
        external
        override
        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 iOVM_L1ERC20Bridge
     */
    function finalizeERC20Withdrawal(
        address _l1Token,
        address _l2Token,
        address _from,
        address _to,
        uint256 _amount,
        bytes calldata _data
    )
        external
        override
        onlyFromCrossDomainAccount(l2TokenBridge)
    {
        deposits[_l1Token][_l2Token] = deposits[_l1Token][_l2Token].sub(_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 {}
}

// File: contracts/optimistic-ethereum/iOVM/bridge/messaging/iOVM_CrossDomainMessenger.sol



// SPDX-License-Identifier: MIT
pragma solidity >0.5.0 <0.8.0;
pragma experimental ABIEncoderV2;

/**
 * @title iOVM_CrossDomainMessenger
 */
interface iOVM_CrossDomainMessenger {

    /**********
     * Events *
     **********/

    event SentMessage(bytes message);
    event RelayedMessage(bytes32 msgHash);
    event FailedRelayedMessage(bytes32 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;
}

// File: contracts/optimistic-ethereum/iOVM/bridge/tokens/iOVM_L1ERC20Bridge.sol



// SPDX-License-Identifier: MIT
pragma solidity >0.5.0;
pragma experimental ABIEncoderV2;

/**
 * @title iOVM_L1ERC20Bridge
 */
interface iOVM_L1ERC20Bridge {

    /**********
     * 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 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,
        uint _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,
        uint _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,
        uint _amount,
        bytes calldata _data
    )
        external;
}

// File: contracts/optimistic-ethereum/iOVM/bridge/tokens/iOVM_L1StandardBridge.sol



// SPDX-License-Identifier: MIT
pragma solidity >0.5.0;
pragma experimental ABIEncoderV2;

import './iOVM_L1ERC20Bridge.sol';

/**
 * @title iOVM_L1StandardBridge
 */
interface iOVM_L1StandardBridge is iOVM_L1ERC20Bridge {

    /**********
     * 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,
        uint _amount,
        bytes calldata _data
    )
        external;
}

// File: contracts/optimistic-ethereum/iOVM/bridge/tokens/iOVM_L2ERC20Bridge.sol



// SPDX-License-Identifier: MIT
pragma solidity >0.5.0;
pragma experimental ABIEncoderV2;

/**
 * @title iOVM_L2ERC20Bridge
 */
interface iOVM_L2ERC20Bridge {

    /**********
     * 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 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,
        uint _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,
        uint _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 OVM_l1TokenGateway.
     * @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,
        uint _amount,
        bytes calldata _data
    )
        external;

}

// File: contracts/optimistic-ethereum/libraries/bridge/OVM_CrossDomainEnabled.sol



// SPDX-License-Identifier: MIT
pragma solidity >0.5.0 <0.8.0;

/* Interface Imports */
import { iOVM_CrossDomainMessenger } from "../../iOVM/bridge/messaging/iOVM_CrossDomainMessenger.sol";

/**
 * @title OVM_CrossDomainEnabled
 * @dev Helper contract for contracts performing cross-domain communications
 *
 * Compiler used: defined by inheriting contract
 * Runtime target: defined by inheriting contract
 */
contract OVM_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 (
            iOVM_CrossDomainMessenger
        )
    {
        return iOVM_CrossDomainMessenger(messenger);
    }

    /**
     * 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);
    }
}

// File: contracts/optimistic-ethereum/libraries/constants/Lib_PredeployAddresses.sol



// SPDX-License-Identifier: MIT
pragma solidity >0.5.0 <0.8.0;

/**
 * @title Lib_PredeployAddresses
 */
library Lib_PredeployAddresses {
    address internal constant L2_TO_L1_MESSAGE_PASSER = 0x4200000000000000000000000000000000000000;
    address internal constant L1_MESSAGE_SENDER = 0x4200000000000000000000000000000000000001;
    address internal constant DEPLOYER_WHITELIST = 0x4200000000000000000000000000000000000002;
    address internal constant ECDSA_CONTRACT_ACCOUNT = 0x4200000000000000000000000000000000000003;
    address internal constant SEQUENCER_ENTRYPOINT = 0x4200000000000000000000000000000000000005;
    address payable internal constant OVM_ETH = 0x4200000000000000000000000000000000000006;
    address internal constant L2_CROSS_DOMAIN_MESSENGER = 0x4200000000000000000000000000000000000007;
    address internal constant LIB_ADDRESS_MANAGER = 0x4200000000000000000000000000000000000008;
    address internal constant PROXY_EOA = 0x4200000000000000000000000000000000000009;
    address internal constant EXECUTION_MANAGER_WRAPPER = 0x420000000000000000000000000000000000000B;
    address internal constant SEQUENCER_FEE_WALLET = 0x4200000000000000000000000000000000000011;
    address internal constant ERC1820_REGISTRY = 0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24;
    address internal constant L2_STANDARD_BRIDGE = 0x4200000000000000000000000000000000000010;
}