game.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/access/Ownable.sol";


//this is an NFT contract 
contract NFTGAMEPLAY is ERC721, Ownable {


//define characters in the game
    enum type_character { PROFESSOR, LISBON }

//counter variable
    uint nextId = 0;

//defining features of a character
    struct Character {
        uint8 attack;
        uint8 defense;
        uint life;
        uint32 experience;
        uint lastHeal;
        uint lastFight;
        type_character typeCharacter;
    }


//create character NFT
    function mint(type_character _typeCharacter) public {
        require(balanceOf(msg.sender) <= 4, "Already create max characters.");
        require(_typeCharacter == type_character.PROFESSOR || _typeCharacter == type_character.LISBON, "Not valid");
        if(_typeCharacter == type_character.PROFESSOR) {
            Character memory thisCharacter = Character(20, 15, 100, 1, block.timestamp, block.timestamp, type_character.PROFESSOR);
            _characterDetails[nextId] = thisCharacter;
            _safeMint(msg.sender, nextId);
            nextId++;
        }
        if(_typeCharacter == type_character.LISBON) {
            Character memory thisCharacter = Character(13, 25, 80, 1, block.timestamp, block.timestamp, type_character.LISBON);
            _characterDetails[nextId] = thisCharacter;
            _safeMint(msg.sender, nextId);
            nextId++;
        }
    }


//NFT with more HP wins
    function fight(uint _tokenId1, uint _tokenId2) public payable {

        // Character 1 kills character 2, character 2 cannot reply
        if(_characterDetails[_tokenId2].life - substractLifeToCharacter2 <= 0) {
            _characterDetails[_tokenId2].life = 0;
            _characterDetails[_tokenId1].experience++;
        }
     
    }


}