Init Connext connector

contracts/optimism/connectors/connext/events.sol

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+//SPDX-License-Identifier: MIT
+pragma solidity ^0.7.0;
+
+contract Events {
+	event LogXCall(
+    uint32 destination,
+    address to,
+    address asset,
+    address delegate,
+    uint256 amount,
+    uint256 slippage,
+    bytes callData,
+		uint256 getId
+	);
+}

contracts/optimism/connectors/connext/helpers.sol

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+//SPDX-License-Identifier: MIT
+pragma solidity ^0.7.0;
+
+import { TokenInterface } from "../../common/interfaces.sol";
+import { DSMath } from "../../common/math.sol";
+import { Basic } from "../../common/basic.sol";
+import { IConnext } from "./interface.sol";
+import { IInstaReceiver } from "./interface.sol";
+
+contract Helpers is DSMath, Basic {
+  /**
+   * @dev Connext Diamond Address
+   */
+  address internal constant connextAddr = 0x8f7492DE823025b4CfaAB1D34c58963F2af5DEDA;
+	IConnext internal constant connext = IConnext(connextAddr);
+
+  /**
+   * @dev InstaReceiver Address
+   */
+	address internal constant instaReceiverAddr = 0x0000000000000000000000000000000000000000; // TODO: Add InstaReceiver address
+	IInstaReceiver internal constant instaReceiver = IInstaReceiver(instaReceiverAddr);
+
+	/**
+	 * @param destination The destination domain ID.
+	 * @param asset he address of token to be bridged.(For USDC: 0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174)
+	 * @param delegate The address to recieve the token on destination chain.
+	 * @param amount The total amount sent by user (Includes bonder fee, destination chain Tx cost).
+	 * @param slippage The fee to be recieved by bonder at destination chain.
+	 * @param relayerFee Relayer fee paid in origin native asset.
+	 * @param callData minimum amount of token out for swap on source chain.
+	 */
+	struct XCallParams {
+    uint32 destination;
+    address to;
+    address asset;
+    address delegate;
+    uint256 amount;
+    uint256 slippage;
+    uint256 relayerFee;
+    bytes callData;
+	}
+
+	function _xcall(XCallParams memory params) internal {
+    TokenInterface tokenContract = TokenInterface(params.asset);
+
+		bool isNative = params.asset == ethAddr;
+
+		uint256 nativeTokenAmt;
+		if (isNative) {
+			// xcall does not take native asset, must wrap 
+			convertEthToWeth(true, tokenContract, params.amount);
+			params.amount = params.amount == uint256(-1)
+				? address(this).balance
+				: params.amount;
+
+			nativeTokenAmt = params.amount;
+		} else {
+			params.amount = params.amount == uint256(-1)
+				? tokenContract.balanceOf(address(this))
+				: params.amount;
+
+			nativeTokenAmt = 0;
+		}
+
+    if (!isNative && params.amount > 0) {
+      approve(tokenContract, connextAddr, params.amount);
+    }
+
+		connext.xcall{ value: params.relayerFee + nativeTokenAmt }(
+			params.destination,
+			params.to,
+      params.asset,
+			params.delegate,
+			params.amount,
+			params.slippage,
+			params.callData
+		);
+	}
+}

contracts/optimism/connectors/connext/interface.sol

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+//SPDX-License-Identifier: MIT
+pragma solidity ^0.7.0;
+
+interface IConnext {
+  function xcall(
+    uint32 _destination,
+    address _to,
+    address _asset,
+    address _delegate,
+    uint256 _amount,
+    uint256 _slippage,
+    bytes calldata _callData
+  ) external payable returns (bytes32);
+}
+
+interface IInstaReceiver {
+  function withdraw(
+    address _asset,
+    uint256 _amount
+  ) external returns (bytes memory);
+
+  function xReceive(
+    bytes32 _transferId,
+    uint256 _amount,
+    address _asset,
+    address _originSender,
+    uint32 _origin,
+    bytes memory _callData
+  ) external returns (bytes memory);
+}

contracts/optimism/connectors/connext/main.sol

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+//SPDX-License-Identifier: MIT
+pragma solidity ^0.7.0;
+pragma experimental ABIEncoderV2;
+
+/**
+ * @title Connext.
+ * @dev Cross chain bridge.
+ */
+
+import { TokenInterface, MemoryInterface } from "../../common/interfaces.sol";
+import { Stores } from "../../common/stores.sol";
+import "./interface.sol";
+import "./helpers.sol";
+import "./events.sol";
+
+abstract contract ConnextResolver is Helpers {
+	/**
+	 * @dev Call xcall on Connext.
+	 * @notice Call xcall on Connext.
+	 * @param params XCallParams struct.
+	 * @param getId ID to retrieve amount from last spell.
+	 */
+	function xcall(XCallParams memory params, uint256 getId)
+		external
+		payable
+		returns (string memory _eventName, bytes memory _eventParam)
+	{
+		params.amount = getUint(getId, params.amount);
+		TokenInterface tokenContract = TokenInterface(params.asset);
+
+		_xcall(params);
+
+		_eventName = "LogXCall(uint32,address,address,address,uint256,uint256,bytes,uint256)";
+		_eventParam = abi.encode(
+			params.destination,
+			params.to,
+      params.asset,
+			params.delegate,
+			params.amount,
+			params.slippage,
+			params.callData,
+			getId
+		);
+	}
+
+	/**
+	 * @dev Delegatecall'ed by DSA.
+	 * @notice Withdraw from the receiver contract to the calling DSA.
+	 * @param asset Address of the asset to withdraw.
+	 * @param getId ID to retrieve amount from last spell.
+	 */
+	function withdraw(address asset, uint256 amount, uint256 getId) external {
+		uint256 _amt = getUint(getId, amount);
+		instaReceiver.withdraw(asset, _amt);
+	}
+}
+
+contract ConnectV2ConnextOptimism is ConnextResolver {
+	string public constant name = "Connext-v1.0";
+}