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t_01...bbdd.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity ^0.8.14;

contract Crud {
    
    address public owner;
    constructor () {
        owner = msg.sender;
    }

    struct User {
        uint256 id;
        string name;
        string curso;
        uint256 createdAt;
    }
    User [] public users;
    uint256 public nextId;

    modifier onlyOwner(){
        require(msg.sender == owner, "Only owner can emit new certificate");
        _;
    }

    function createUser(string memory _name,  string memory _curso) public onlyOwner {
        users.push (User(
            nextId,
            _name,
            _curso,
            block.timestamp
        ));
        nextId++;
    }

    function findByNameFirst (string memory _name) public view returns(User memory _user) {
        for (uint256 i=0; i<users.length; i++){
            if ( keccak256(abi.encodePacked(_name)) == keccak256(abi.encodePacked(users[i].name)) ) {
                _user = users[i];
            }
        }
        return _user;
    }

    function findByNameList (string memory _name) public view returns( uint256 [] memory) {
        uint[] memory _ids = new uint[](users.length);
        for (uint256 i=0; i<users.length; i++){
            if ( keccak256(abi.encodePacked(_name)) == keccak256(abi.encodePacked(users[i].name)) ) {
                _ids[i]=i;
            }else{
                _ids[i]=999999;
            }
        }
        return _ids;
    }

    function findById (uint256 _id) public view returns (string memory, string memory, uint256){
        return (users[_id].name, users[_id].curso, users[_id].createdAt);
    }

    function update(uint256  _id, string memory _name, string memory _curso) public onlyOwner { 
        if (keccak256(bytes(_name)) != keccak256(bytes(""))) {
            users[_id].name = _name;
        }
        if (keccak256(bytes(_curso)) != keccak256(bytes(""))) {
            users[_id].curso = _curso;
        }
    }

    function deleteById (uint256 _id) public onlyOwner {
        delete users[_id];
    }



}