MessageEmitter

{{
  "language": "Solidity",
  "sources": {
    "src/v0.8/keystone/MessageEmitter.sol": {
      "content": "// SPDX-License-Identifier: MIT
pragma solidity 0.8.24;

import {ITypeAndVersion} from "../shared/interfaces/ITypeAndVersion.sol";

/// @notice MessageEmitter is used to emit custom messages from a contract.
/// @dev Sender may only emit a message once per block timestamp.
contract MessageEmitter is ITypeAndVersion {
    string public constant override typeAndVersion = "ContractEmitter 1.0.0";

    event MessageEmitted(address indexed emitter, uint256 indexed timestamp, string message);

    mapping(bytes32 key => string message) private s_messages;
    mapping(address emitter => string message) private s_lastMessage;

    function emitMessage(
        string calldata message
    ) public {
        require(bytes(message).length > 0, "Message cannot be empty");
        bytes32 key = _hashKey(msg.sender, block.timestamp);
        require(bytes(s_messages[key]).length == 0, "Message already exists for the same sender and block timestamp");
        s_messages[key] = message;
        s_lastMessage[msg.sender] = message;
        emit MessageEmitted(msg.sender, block.timestamp, message);
    }

    function getMessage(address emitter, uint256 timestamp) public view returns (string memory) {
        bytes32 key = _hashKey(emitter, timestamp);
        require(bytes(s_messages[key]).length == 0, "Message does not exist for the given sender and timestamp");
        return s_messages[key];
    }

    function getLastMessage(
        address emitter
    ) public view returns (string memory) {
        require(bytes(s_lastMessage[emitter]).length > 0, "No last message for the given sender");
        return s_lastMessage[emitter];
    }

    function _hashKey(address emitter, uint256 timestamp) internal pure returns (bytes32) {
        return keccak256(abi.encode(emitter, timestamp));
    }
}"
    },
    "src/v0.8/shared/interfaces/ITypeAndVersion.sol": {
      "content": "// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface ITypeAndVersion {
  function typeAndVersion() external pure returns (string memory);
}
"
    }
  },
  "settings": {
    "remappings": [
      "forge-std/=src/v0.8/vendor/forge-std/src/",
      "@openzeppelin/contracts@4.7.3/=node_modules/@openzeppelin/contracts-4.7.3/",
      "@openzeppelin/contracts@4.8.3/=node_modules/@openzeppelin/contracts-4.8.3/",
      "@openzeppelin/contracts@4.9.6/=node_modules/@openzeppelin/contracts-4.9.6/",
      "@openzeppelin/contracts@5.0.2/=node_modules/@openzeppelin/contracts-5.0.2/",
      "@openzeppelin/contracts@5.1.0/=node_modules/@openzeppelin/contracts-5.1.0/",
      "@openzeppelin/contracts-upgradeable/=node_modules/@openzeppelin/contracts-upgradeable/",
      "@arbitrum/=node_modules/@arbitrum/",
      "hardhat/=node_modules/hardhat/",
      "@eth-optimism/=node_modules/@eth-optimism/",
      "@scroll-tech/=node_modules/@scroll-tech/",
      "@zksync/=node_modules/@zksync/"
    ],
    "optimizer": {
      "enabled": true,
      "runs": 1000000
    },
    "metadata": {
      "useLiteralContent": false,
      "bytecodeHash": "none",
      "appendCBOR": true
    },
    "outputSelection": {
      "*": {
        "*": [
          "evm.bytecode",
          "evm.deployedBytecode",
          "devdoc",
          "userdoc",
          "metadata",
          "abi"
        ]
      }
    },
    "evmVersion": "paris",
    "viaIR": false
  }
}}