feat: add NextLockboxAdapter

contracts/integration/Connext/NextLockboxAdapter.sol

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.13;
+
+import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
+import {IXERC20} from "../../shared/IXERC20/IXERC20.sol";
+import {IXERC20Lockbox} from "../../shared/IXERC20/IXERC20Lockbox.sol";
+import {IXReceiver} from "@connext/interfaces/core/IXReceiver.sol";
+
+contract NextLockboxAdapter is IXReceiver {
+  IXERC20Lockbox public lockbox;
+  IERC20 public erc20;
+  IXERC20 public xerc20;
+
+  constructor(address _lockbox, address _erc20, address _xerc20) {
+    lockbox = IXERC20Lockbox(_lockbox);
+    erc20 = IERC20(_erc20);
+    xerc20 = IXERC20(_xerc20);
+  }
+
+  /// @notice Deposit ERC20s into the Lockbox
+  /// @param _amount Amount of ERC20s to use
+  /// @param _recipient Recipient of the xERC20s
+  function deposit(uint256 _amount, address _recipient) internal {
+    require(_amount > 0, "Zero amount");
+    IERC20 _xerc20 = IERC20(address(xerc20));
+
+    if (erc20.allowance(address(this), address(lockbox)) < _amount) {
+      erc20.approve(address(lockbox), type(uint256).max);
+    }
+    lockbox.deposit(_amount);
+
+    // Transfer the xERC20s to the recipient
+    SafeERC20.safeTransfer(_xerc20, _recipient, _amount);
+  }
+
+  /// @notice Withdraw ERC20s from the Lockbox
+  /// @param _amount Amount of xERC20s to use
+  /// @param _recipient Recipient of the ERC20s
+  function withdraw(uint256 _amount, address _recipient) internal {
+    require(_amount > 0, "Zero amount");
+    IERC20 _xerc20 = IERC20(address(xerc20));
+
+    if (_xerc20.allowance(address(this), address(lockbox)) < _amount) {
+      _xerc20.approve(address(lockbox), type(uint256).max);
+    }
+    lockbox.withdraw(_amount);
+
+    // Transfer the ERC20s to the recipient
+    SafeERC20.safeTransfer(erc20, _recipient, _amount);
+  }
+
+  /// @dev This function receives xERC20s from Connext and calls the Lockbox
+  /// @param _amount The amount of funds that will be received.
+  /// @param _asset The address of the asset that will be received.
+  /// @param _transferId The id of the transfer.
+  /// @param _callData The data that will be sent to the targets.
+  function xReceive(
+    bytes32 _transferId,
+    uint256 _amount,
+    address _asset,
+    address _originSender,
+    uint32 _origin,
+    bytes memory _callData
+  ) external returns (bytes memory) {
+    // Check for the right xerc20
+    require(_asset == address(xerc20), "Wrong asset received");
+
+    // Unpack the _callData to get the recipient's address
+    address _recipient = abi.decode(_callData, (address));
+
+    withdraw(_amount, _recipient);
+  }
+}

script/Connext/DeployNextLockboxAdapter.s.sol

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.13;
+
+import "forge-std/Script.sol";
+import {NextLockboxAdapter} from "../../contracts/integration/Connext/NextLockboxAdapter.sol";
+
+contract DeployNextLockboxAdapter is Script {
+  function run(address lockbox, address erc20, address xerc20) external {
+    vm.startBroadcast();
+
+    new NextLockboxAdapter(lockbox, erc20, xerc20);
+
+    vm.stopBroadcast();
+  }
+}