ERC721 Contract

nft-contract-with-custom-price.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

import "@openzeppelin/contracts@4.8.3/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts@4.8.3/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts@4.8.3/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts@4.8.3/access/Ownable.sol";
import "@openzeppelin/contracts@4.8.3/utils/Counters.sol";

contract $PEPE is ERC721, ERC721URIStorage, Ownable {
    using Counters for Counters.Counter;
    Counters.Counter private _tokenIdCounter;
    address Erc20tokenAddress;
    struct NFTData {
        uint256 price;
        address erc20Address;
        string uri;
        bool isSold;
    }
    mapping (uint256 => NFTData) public nftData;
    constructor(address tokenAddress) ERC721("$PEPE NFT", "PEPE NFT") {
        Erc20tokenAddress = tokenAddress;
    }

    function buyNft(uint256 tokenid) public {
        uint256 erc20Balance = IERC20(nftData[tokenid].erc20Address).balanceOf(msg.sender);   
        uint256 allowance = IERC20(nftData[tokenid].erc20Address).allowance(msg.sender, address(this)); 
        require(!nftData[tokenid].isSold, "Tokenid already sold");
        require(erc20Balance >= nftData[tokenid].price, "Insufficient ERC20 token balance");
        require(allowance >= nftData[tokenid].price, "Insufficient ERC20 token allowance");
        IERC20(nftData[tokenid].erc20Address).transferFrom(msg.sender, address(this), nftData[tokenid].price);   
        _tokenIdCounter.increment();
        _safeMint(msg.sender, tokenid);
        _setTokenURI(tokenid, nftData[tokenid].uri); 
        nftData[tokenid].isSold = true;
    }

    function addNft(uint256 price, string memory uri) public onlyOwner {
        uint256 tokenId = _tokenIdCounter.current();
        nftData[tokenId] = NFTData(price, Erc20tokenAddress, uri, false);
    }
    function getTokenPrice(uint256 tokenid) public view returns  (uint256) {
        return nftData[tokenid].price;
    }
    function getTokenErcAddress(uint256 tokenid) public view returns  (address) {
        return nftData[tokenid].erc20Address;
    }
    function isTokenSold(uint256 tokenid) public view returns  (bool) {
        return nftData[tokenid].isSold;
    } 


    function _burn(uint256 tokenId) internal override(ERC721, ERC721URIStorage) {
        super._burn(tokenId);
    }

    function tokenURI(uint256 tokenId)
        public
        view
        override(ERC721, ERC721URIStorage)
        returns (string memory)
    {
        return super.tokenURI(tokenId);
    }
}