MyEpicNFT.sol

pragma solidity ^0.8.0;

// We first import some OpenZeppelin Contracts.
import "@openzeppelin/contracts/utils/Strings.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
import "hardhat/console.sol";

import { Base64 } from "./libraries/Base64.sol"; 

// We inherit the contract we imported. This means we'll have access
// to the inherited contract's methods.
contract MyEpicNFT is ERC721URIStorage {
  // Magic given to us by OpenZeppelin to help us keep track of tokenIds.
  using Counters for Counters.Counter;
  Counters.Counter private _tokenIds;


  string svgPartOne = "<svg xmlns='http://www.w3.org/2000/svg' preserveAspectRatio='xMinYMin meet' viewBox='0 0 350 350'><style>.base { fill: white; font-family: serif; font-size: 24px; }</style><rect width='100%' height='100%' fill='";
  string svgPartTwo = "'/><text x='50%' y='50%' class='base' dominant-baseline='middle' text-anchor='middle'>";

string[] firstWords = ["STARTUP", "LAUNCH", "RAISE", "UNICORN", "TEST", "IDEATE"];
string[] secondWords = ["BRAINSTORM", "CUSTOMER", "PRODUCT", "MARKETING", "TEAM", "TECHCRUNCH"];
string[] thirdWords = ["YC", "PUBLIC", "IPO", "REVENUE", "MARKET CAP", "CASH FLOW"];

string[] colors = ["red","blue","black","yellow"];

event NewEpicNFTMinted(address sender, uint256 tokenId);
 
constructor() ERC721 ("SquareNFT", "SQUARE") {
    console.log("This is my NFT contract. Woah!");
  }
function pickRandomFirstWord(uint256 tokenId) public view returns (string memory) {
    // I seed the random generator. More on this in the lesson. 
    uint256 rand = random(string(abi.encodePacked("FIRST_WORD", Strings.toString(tokenId))));
    // Squash the # between 0 and the length of the array to avoid going out of bounds.
    rand = rand % firstWords.length;
    return firstWords[rand];
  }

  function pickRandomSecondWord(uint256 tokenId) public view returns (string memory) {
    uint256 rand = random(string(abi.encodePacked("SECOND_WORD", Strings.toString(tokenId))));
    rand = rand % secondWords.length;
    return secondWords[rand];
  }

  function pickRandomThirdWord(uint256 tokenId) public view returns (string memory) {
    uint256 rand = random(string(abi.encodePacked("THIRD_WORD", Strings.toString(tokenId))));
    rand = rand % thirdWords.length;
    return thirdWords[rand];
  }

  function pickRandomColor(uint256 tokenId) public view returns (string memory) {
    uint256 rand = random(string(abi.encodePacked("COLOR", Strings.toString(tokenId))));
    rand = rand % colors.length;
    return colors[rand];
  }

  function random(string memory input) internal pure returns (uint256) {
      return uint256(keccak256(abi.encodePacked(input)));
  }
  // We need to pass the name of our NFTs token and it's symbol.
 

  // A function our user will hit to get their NFT.
  function makeAnEpicNFT() public {
     // Get the current tokenId, this starts at 0.
    uint256 newItemId = _tokenIds.current();

    string memory first = pickRandomFirstWord(newItemId);
    string memory second = pickRandomSecondWord(newItemId);
    string memory third = pickRandomThirdWord(newItemId);
    string memory combinedWord = string(abi.encodePacked(first, second, third));

    string memory randomColor = pickRandomColor(newItemId);
    string memory finalSvg = string(abi.encodePacked(svgPartOne, randomColor, svgPartTwo, combinedWord, "</text></svg>"));

    string memory json = Base64.encode(
        bytes(
            string(
                abi.encodePacked(
                    '{"name": "',
                    // We set the title of our NFT as the generated word.
                    combinedWord,
                    '", "description": "A highly acclaimed collection of squares.", "image": "data:image/svg+xml;base64,',
                    // We add data:image/svg+xml;base64 and then append our base64 encode our svg.
                    Base64.encode(bytes(finalSvg)),
                    '"}'
                )
            )
        )
    );
    string memory finalTokenUri = string(
        abi.encodePacked("data:application/json;base64,", json)
    );

    console.log("\n--------------------");
    console.log(finalTokenUri);
    console.log("--------------------\n");

    _safeMint(msg.sender, newItemId);
    
    // Update your URI!!!
    _setTokenURI(newItemId, finalTokenUri);
  
    _tokenIds.increment();
    console.log("An NFT w/ ID %s has been minted to %s", newItemId, msg.sender);
    emit NewEpicNFTMinted(msg.sender, newItemId);
  }
}