// SPDX-License-Identifier: MIT

pragma solidity >=0.7.0 <0.9.0;

/**
 * @title UTStamp
 */
contract UTStamp {
    address public owner;

    string public stamp;

    event StampCommit(string indexed stampIndex, string stamp);

    modifier isOwner() {
        require(msg.sender == owner, "Caller is not owner");
        _;
    }

    modifier validate(string memory newStamp) {
        require(bytes(newStamp).length == 64, "stamp length should be 64");
        _;
    }

    constructor() {
        owner = msg.sender;
    }

    function commitStamp(string memory newStamp)
        public
        isOwner
        validate(newStamp)
    {
        emit StampCommit(newStamp, newStamp);
        stamp = newStamp;
    }
}

{
  "compilationTarget": {
    "UTStamp.sol": "UTStamp"
  },
  "evmVersion": "shanghai",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}