add AmoyReceiver contract for receiving messages from the Sepolia chain

Author: cqlyj

src/AmoyReceiver.sol

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.26;
+
+import {Client} from "@chainlink/contracts/src/v0.8/ccip/libraries/Client.sol";
+import {CCIPReceiver} from "@chainlink/contracts/src/v0.8/ccip/applications/CCIPReceiver.sol";
+
+/// @title AmoyReceiverAndTokenSender
+/// @author Luo Yingjie
+/// @notice This contract will receive the message sent from sepolia chain
+/// @notice This contract will be deployed on the amoy chain
+contract AmoyReceiver is CCIPReceiver {
+    event MessageReceived(
+        bytes32 indexed messageId, // The unique ID of the message.
+        uint64 indexed sourceChainSelector, // The chain selector of the source chain.
+        address sender, // The address of the sender from the source chain.
+        bytes signedMessage // The signed message that approves the token transfer
+    );
+
+    bytes32 private s_messageId;
+    bytes private s_signedMessage;
+
+    /// @notice Constructor initializes the contract with the router address.
+    /// @param router The address of the router contract.
+    constructor(address router) CCIPReceiver(router) {}
+
+    /// handle a received message
+    function _ccipReceive(
+        Client.Any2EVMMessage memory any2EvmMessage
+    ) internal override {
+        s_messageId = any2EvmMessage.messageId;
+        s_signedMessage = any2EvmMessage.data;
+
+        emit MessageReceived(
+            any2EvmMessage.messageId,
+            any2EvmMessage.sourceChainSelector, // fetch the source chain identifier (aka selector)
+            abi.decode(any2EvmMessage.sender, (address)), // abi-decoding of the sender address,
+            abi.decode(any2EvmMessage.data, (bytes)) // abi-decoding of the signed message
+        );
+    }
+
+    function getMessageId() external view returns (bytes32) {
+        return s_messageId;
+    }
+
+    function getSignedMessage() external view returns (bytes memory) {
+        return s_signedMessage;
+    }
+}