contract grandpaapenursingclub is ERC721Enumerable, Ownable {
    using Strings for uint256;

    using Counters for Counters.Counter;
    Counters.Counter private _tokenIds;

    string private baseURI;
    string public baseExtension = ".json";
    uint256 public cost = 0.05 ether;
    uint256 public maxSupply = 10101;
    uint256 public maxMintAmount = 20;
    bool public paused = false;
    bool public revealed = false;
    string public notRevealedUri;

    constructor(
        string memory _name,
        string memory _symbol,
        string memory _initNotRevealedUri
        ) ERC721(_name, _symbol) {
        setNotRevealedURI(_initNotRevealedUri);
    }

    // internal
    function _baseURI() internal view virtual override returns (string memory) {
        return baseURI;
    }

    function founderMint(uint256 _mintAmount) public onlyOwner {
        require(!paused);
        require(_mintAmount > 0 && _mintAmount <= maxMintAmount);
        require(_tokenIds.current() + _mintAmount <= maxSupply);

        for (uint256 i = 1; i <= _mintAmount; i++) {
            _tokenIds.increment();
            _safeMint(msg.sender, _tokenIds.current());
        }
    }

    // public
    function mint(uint256 _mintAmount) public payable {
        require(!paused);
        require(_mintAmount > 0 && _mintAmount <= maxMintAmount);
        require(_tokenIds.current() + _mintAmount <= maxSupply);

        require(msg.value >= cost * _mintAmount);

        for (uint256 i = 1; i <= _mintAmount; i++) {
            _tokenIds.increment();
            _safeMint(msg.sender, _tokenIds.current());
        }
    }

    function walletOfOwner(address _owner)
        public
        view
        returns (uint256[] memory)
    {
        uint256 ownerTokenCount = balanceOf(_owner);
        uint256[] memory tokenIds = new uint256[](ownerTokenCount);
        for (uint256 i; i < ownerTokenCount; i++) {
            tokenIds[i] = tokenOfOwnerByIndex(_owner, i);
        }
        return tokenIds;
    }

    function tokenURI(uint256 tokenId)
        public
        view
        virtual
        override
        returns (string memory)
    {
        require(
                _exists(tokenId),
            "ERC721Metadata: URI query for nonexistent token"
        );

        if(revealed == false && msg.sender != owner()) {
            return notRevealedUri;
        }

        string memory currentBaseURI = _baseURI();
        return bytes(currentBaseURI).length > 0
            ? string(abi.encodePacked(currentBaseURI, tokenId.toString(), baseExtension))
            : "";
    }

    //only owner
    function reveal() public onlyOwner() {
        revealed = true;
    }

    //only owner
    function hide() public onlyOwner() {
        revealed = false;
    }

    function setCost(uint256 _newCost) public onlyOwner() {
        cost = _newCost;
    }

    function setmaxMintAmount(uint256 _newmaxMintAmount) public onlyOwner() {
        maxMintAmount = _newmaxMintAmount;
    }

    function setNotRevealedURI(string memory _notRevealedURI) public onlyOwner {
        notRevealedUri = _notRevealedURI;
    }

    function setBaseURI(string memory _newBaseURI) public onlyOwner {
        baseURI = _newBaseURI;
    }

    function setBaseExtension(string memory _newBaseExtension) public onlyOwner {
        baseExtension = _newBaseExtension;
    }

    function pause(bool _state) public onlyOwner {
        paused = _state;
    }

    function withdraw() public payable onlyOwner {
        (bool success, ) = payable(msg.sender).call{value: address(this).balance}("");
        require(success);
    }
}
function _baseURI() internal view virtual override returns (string memory) {
        return baseURI;
    }
// internal