From 73eb4ccde78876f7bd687d495c5318f2bb8a3880 Mon Sep 17 00:00:00 2001
From: CJ42 <cavallerajean@gmail.com>
Date: Tue, 24 Sep 2024 08:57:37 +0800
Subject: [PATCH] refactor: override functions to extract params from LSP7
 calldata

---
 README.md                   |  7 ++++++-
 src/HypLSP7.sol             | 24 ++++++++++++++++++++++++
 src/TokenMessageForLSP7.sol | 25 +++++++++++++++++++++++++
 3 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 src/TokenMessageForLSP7.sol

diff --git a/README.md b/README.md
index cc5e2fe..5545342 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,11 @@
 
 ## Architecture & Workflow
 
+The flow for bridging tokens is generally as follow:
+
+- if the token is originally from ETH, the token is locked on ETHEREUM, and minted on LUKSO.
+- if the token is originally from LUKSO, the token is burnt on LUKSO, minted on ETHEREUM.
+
 ### Ethereum -> LUKSO
 
 ![Ethereum to LUKSO bridge flow](./assets/flow-ethereum-lukso-hashi-bridge.png)
@@ -79,8 +84,8 @@
 
 ### Relevant links & resources
 
-- [Architecture diagrams](https://hackmd.io/WXwzLS5TS4q_G3C7w2DkiA)
 - [Cross Chain Alliance - Hashi](https://crosschain-alliance.gitbook.io/hashi)
+- [Hyperlane smart contracts monorepo](https://github.com/hyperlane-xyz/hyperlane-monorepo)
 
 ## Getting Started
 
diff --git a/src/HypLSP7.sol b/src/HypLSP7.sol
index b5bbca0..cd4cd60 100644
--- a/src/HypLSP7.sol
+++ b/src/HypLSP7.sol
@@ -6,6 +6,9 @@ import { LSP7DigitalAssetInitAbstract } from "@lukso/lsp7-contracts/contracts/LS
 import { TokenRouter } from "@hyperlane-xyz/core/contracts/token/libs/TokenRouter.sol";
 import { OwnableUpgradeable } from "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
 
+// libraries
+import { TokenMessageForLSP7 } from "./TokenMessageForLSP7.sol";
+
 /**
  * @title LSP7 version of the Hyperlane ERC20 Token Router
  * @dev https://github.com/hyperlane-xyz/hyperlane-monorepo/blob/main/solidity/contracts/token/HypERC20.sol
@@ -90,4 +93,25 @@ contract HypLSP7 is LSP7DigitalAssetInitAbstract, TokenRouter {
     {
         LSP7DigitalAssetInitAbstract._mint(_recipient, _amount, true, "");
     }
+
+    function _transferRemote(
+        uint32 _destination,
+        bytes32 _recipient,
+        uint256 _amountOrId,
+        uint256 _value,
+        bytes memory _hookMetadata,
+        address _hook
+    )
+        internal
+        virtual
+        override(TokenRouter)
+        returns (bytes32 messageId)
+    {
+        bytes memory _tokenMetadata = _transferFromSender(_amountOrId);
+        bytes memory _tokenMessage = TokenMessageForLSP7.format(_recipient, _amountOrId, _tokenMetadata);
+
+        messageId = _Router_dispatch(_destination, _value, _tokenMessage, _hookMetadata, _hook);
+
+        emit SentTransferRemote(_destination, _recipient, _amountOrId);
+    }
 }
diff --git a/src/TokenMessageForLSP7.sol b/src/TokenMessageForLSP7.sol
new file mode 100644
index 0000000..5da1ebb
--- /dev/null
+++ b/src/TokenMessageForLSP7.sol
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+pragma solidity >=0.8.0;
+
+/// @dev Adjusted version of the TokenMessage library from Hyperlane
+/// to extract parameters from the calldata of an LSP7 transfer
+/// according to the `transfer(address,address,uint256,bool,bytes)` signature.
+library TokenMessageForLSP7 {
+    function format(bytes32 _recipient, uint256 _amount, bytes memory _metadata) internal view returns (bytes memory) {
+        return abi.encodePacked(
+            msg.sender, // TODO: which sender should be specified here? Should we add an extra parameter?
+            _recipient,
+            _amount,
+            true, // force param set to `true` by default
+            _metadata
+        );
+    }
+
+    function recipient(bytes calldata message) internal pure returns (bytes32) {
+        return bytes32(message[32:64]);
+    }
+
+    function amount(bytes calldata message) internal pure returns (uint256) {
+        return uint256(bytes32(message[64:96]));
+    }
+}