add: helper

contracts/optimism/connectors/connext/helpers.sol

@@ -0,0 +1,80 @@
+//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 The address of token to be bridged.
+	 * @param delegate Address that can revert or forceLocal on destination.
+	 * @param amount The amount to transfer.
+	 * @param slippage Maximum amount of slippage the user will accept in BPS.
+	 * @param relayerFee Relayer fee paid in origin native asset.
+	 * @param callData Encoded calldata to send.
+	 */
+	struct XCallParams {
+    uint32 destination;
+    address to;
+    address asset;
+    address delegate;
+    uint256 amount;
+    uint256 slippage;
+    uint256 relayerFee;
+    bytes callData;
+	}
+
+	function _xcall(XCallParams memory params) internal {
+		uint256 nativeTokenAmt;
+		bool isNative = params.asset == ethAddr;
+
+		if (isNative) {
+			params.amount = params.amount == uint256(-1)
+				? address(this).balance
+				: params.amount;
+
+			// xcall does not take native asset, must wrap 
+			TokenInterface tokenContract = TokenInterface(wethAddr);
+			convertEthToWeth(true, tokenContract, params.amount);
+
+			nativeTokenAmt = params.amount;
+		} else {
+			TokenInterface tokenContract = TokenInterface(params.asset);
+			params.amount = params.amount == uint256(-1)
+				? tokenContract.balanceOf(address(this))
+				: params.amount;
+
+			if (params.amount > 0) {
+				tokenContract.approve(connextAddr, params.amount);
+			}
+
+			nativeTokenAmt = 0;
+		}
+
+		connext.xcall{ value: params.relayerFee + nativeTokenAmt }(
+			params.destination,
+			params.to,
+      params.asset,
+			params.delegate,
+			params.amount,
+			params.slippage,
+			params.callData
+		);
+	}
+}