// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

library EnumerableSet {
    struct Set {
        bytes32[] _values;
        mapping (bytes32 => uint256) _indexes;
    }
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        uint256 valueIndex = set._indexes[value];
        if (valueIndex != 0) {
            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;
            bytes32 lastvalue = set._values[lastIndex];
            set._values[toDeleteIndex] = lastvalue;
            set._indexes[lastvalue] = toDeleteIndex + 1;
            set._values.pop();
            delete set._indexes[value];
            return true;
        } else {
            return false;
        }
    }
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        require(set._values.length > index, "EnumerableSet: index out of bounds");
        return set._values[index];
    }
    struct AddressSet {
        Set _inner;
    }
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(value)));
    }
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(value)));
    }
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(value)));
    }
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint256(_at(set._inner, index)));
    }
    struct UintSet {
        Set _inner;
    }
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }
}

library Address {
    function isContract(address account) internal view returns (bool) {
        uint256 size;
        assembly { size := extcodesize(account) }
        return size > 0;
    }
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        return _functionCallWithValue(target, data, value, errorMessage);
    }
    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
            if (returndata.length > 0) {
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }
    function _msgData() internal view virtual returns (bytes memory) {
        this;
        return msg.data;
    }
}

abstract contract AccessControl is Context {
    using EnumerableSet for EnumerableSet.AddressSet;
    using Address for address;
    struct RoleData {
        EnumerableSet.AddressSet members;
        bytes32 adminRole;
    }
    mapping (bytes32 => RoleData) private _roles;
    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);
    function hasRole(bytes32 role, address account) public view returns (bool) {
        return _roles[role].members.contains(account);
    }
    function getRoleMemberCount(bytes32 role) public view returns (uint256) {
        return _roles[role].members.length();
    }
    function getRoleMember(bytes32 role, uint256 index) public view returns (address) {
        return _roles[role].members.at(index);
    }
    function getRoleAdmin(bytes32 role) public view returns (bytes32) {
        return _roles[role].adminRole;
    }
    function grantRole(bytes32 role, address account) public virtual {
        require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to grant");
        _grantRole(role, account);
    }
    function revokeRole(bytes32 role, address account) public virtual {
        require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to revoke");
        _revokeRole(role, account);
    }
    function renounceRole(bytes32 role, address account) public virtual {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");
        _revokeRole(role, account);
    }
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        emit RoleAdminChanged(role, _roles[role].adminRole, adminRole);
        _roles[role].adminRole = adminRole;
    }
    function _grantRole(bytes32 role, address account) private {
        if (_roles[role].members.add(account)) {
            emit RoleGranted(role, account, _msgSender());
        }
    }
    function _revokeRole(bytes32 role, address account) private {
        if (_roles[role].members.remove(account)) {
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

interface IERC165 {
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

interface IERC721 is IERC165 {
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
    function balanceOf(address owner) external view returns (uint256 balance);
    function ownerOf(uint256 tokenId) external view returns (address owner);
    function safeTransferFrom(address from, address to, uint256 tokenId) external;
    function transferFrom(address from, address to, uint256 tokenId) external;
    function approve(address to, uint256 tokenId) external;
    function getApproved(uint256 tokenId) external view returns (address operator);
    function setApprovalForAll(address operator, bool _approved) external;
    function isApprovedForAll(address owner, address operator) external view returns (bool);
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
}

interface IERC721Metadata is IERC721 {
    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

interface IERC721Enumerable is IERC721 {
    function totalSupply() external view returns (uint256);
    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId);
    function tokenByIndex(uint256 index) external view returns (uint256);
}

interface IERC721Receiver {
    function onERC721Received(address operator, address from, uint256 tokenId, bytes calldata data)
    external returns (bytes4);
}

contract ERC165 is IERC165 {
    bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
    mapping(bytes4 => bool) private _supportedInterfaces;
    constructor () internal {
        _registerInterface(_INTERFACE_ID_ERC165);
    }
    function supportsInterface(bytes4 interfaceId) public view override returns (bool) {
        return _supportedInterfaces[interfaceId];
    }
    function _registerInterface(bytes4 interfaceId) internal virtual {
        require(interfaceId != 0xffffffff, "ERC165: invalid interface id");
        _supportedInterfaces[interfaceId] = true;
    }
}

library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;
        return c;
    }
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        return c;
    }
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

library EnumerableMap {
    struct MapEntry {
        bytes32 _key;
        bytes32 _value;
    }
    struct Map {
        MapEntry[] _entries;
        mapping (bytes32 => uint256) _indexes;
    }
    function _set(Map storage map, bytes32 key, bytes32 value) private returns (bool) {
        uint256 keyIndex = map._indexes[key];

        if (keyIndex == 0) {
            map._entries.push(MapEntry({ _key: key, _value: value }));
            map._indexes[key] = map._entries.length;
            return true;
        } else {
            map._entries[keyIndex - 1]._value = value;
            return false;
        }
    }
    function _remove(Map storage map, bytes32 key) private returns (bool) {
        uint256 keyIndex = map._indexes[key];
        if (keyIndex != 0) {
            uint256 toDeleteIndex = keyIndex - 1;
            uint256 lastIndex = map._entries.length - 1;
            MapEntry storage lastEntry = map._entries[lastIndex];
            map._entries[toDeleteIndex] = lastEntry;
            map._indexes[lastEntry._key] = toDeleteIndex + 1;
            map._entries.pop();
            delete map._indexes[key];
            return true;
        } else {
            return false;
        }
    }
    function _contains(Map storage map, bytes32 key) private view returns (bool) {
        return map._indexes[key] != 0;
    }
    function _length(Map storage map) private view returns (uint256) {
        return map._entries.length;
    }
    function _at(Map storage map, uint256 index) private view returns (bytes32, bytes32) {
        require(map._entries.length > index, "EnumerableMap: index out of bounds");
        MapEntry storage entry = map._entries[index];
        return (entry._key, entry._value);
    }
    function _get(Map storage map, bytes32 key) private view returns (bytes32) {
        return _get(map, key, "EnumerableMap: nonexistent key");
    }
    function _get(Map storage map, bytes32 key, string memory errorMessage) private view returns (bytes32) {
        uint256 keyIndex = map._indexes[key];
        require(keyIndex != 0, errorMessage);
        return map._entries[keyIndex - 1]._value;
    }
    struct UintToAddressMap {
        Map _inner;
    }
    function set(UintToAddressMap storage map, uint256 key, address value) internal returns (bool) {
        return _set(map._inner, bytes32(key), bytes32(uint256(value)));
    }
    function remove(UintToAddressMap storage map, uint256 key) internal returns (bool) {
        return _remove(map._inner, bytes32(key));
    }
    function contains(UintToAddressMap storage map, uint256 key) internal view returns (bool) {
        return _contains(map._inner, bytes32(key));
    }
    function length(UintToAddressMap storage map) internal view returns (uint256) {
        return _length(map._inner);
    }
    function at(UintToAddressMap storage map, uint256 index) internal view returns (uint256, address) {
        (bytes32 key, bytes32 value) = _at(map._inner, index);
        return (uint256(key), address(uint256(value)));
    }
    function get(UintToAddressMap storage map, uint256 key) internal view returns (address) {
        return address(uint256(_get(map._inner, bytes32(key))));
    }
    function get(UintToAddressMap storage map, uint256 key, string memory errorMessage) internal view returns (address) {
        return address(uint256(_get(map._inner, bytes32(key), errorMessage)));
    }
}

library Strings {
    function toString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        uint256 index = digits - 1;
        temp = value;
        while (temp != 0) {
            buffer[index--] = byte(uint8(48 + temp % 10));
            temp /= 10;
        }
        return string(buffer);
    }
}

contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Enumerable {
    using SafeMath for uint256;
    using Address for address;
    using EnumerableSet for EnumerableSet.UintSet;
    using EnumerableMap for EnumerableMap.UintToAddressMap;
    using Strings for uint256;
    bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;
    mapping (address => EnumerableSet.UintSet) private _holderTokens;
    EnumerableMap.UintToAddressMap private _tokenOwners;
    mapping (uint256 => address) private _tokenApprovals;
    mapping (address => mapping (address => bool)) private _operatorApprovals;
    string private _name;
    string private _symbol;
    mapping (uint256 => string) private _tokenURIs;
    string private _baseURI;
    bytes4 private constant _INTERFACE_ID_ERC721 = 0x80ac58cd;
    bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;
    bytes4 private constant _INTERFACE_ID_ERC721_ENUMERABLE = 0x780e9d63;
    constructor (string memory name, string memory symbol) public {
        _name = name;
        _symbol = symbol;
        _registerInterface(_INTERFACE_ID_ERC721);
        _registerInterface(_INTERFACE_ID_ERC721_METADATA);
        _registerInterface(_INTERFACE_ID_ERC721_ENUMERABLE);
    }
    function balanceOf(address owner) public view override returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");
        return _holderTokens[owner].length();
    }
    function ownerOf(uint256 tokenId) public view override returns (address) {
        return _tokenOwners.get(tokenId, "ERC721: owner query for nonexistent token");
    }
    function name() public view override returns (string memory) {
        return _name;
    }
    function symbol() public view override returns (string memory) {
        return _symbol;
    }
    function tokenURI(uint256 tokenId) public view override returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
        string memory _tokenURI = _tokenURIs[tokenId];
        if (bytes(_baseURI).length == 0) {
            return _tokenURI;
        }
        if (bytes(_tokenURI).length > 0) {
            return string(abi.encodePacked(_baseURI, _tokenURI));
        }
        return string(abi.encodePacked(_baseURI, tokenId.toString()));
    }
    function baseURI() public view returns (string memory) {
        return _baseURI;
    }
    function tokenOfOwnerByIndex(address owner, uint256 index) public view override returns (uint256) {
        return _holderTokens[owner].at(index);
    }
    function totalSupply() public view override returns (uint256) {
        return _tokenOwners.length();
    }
    function tokenByIndex(uint256 index) public view override returns (uint256) {
        (uint256 tokenId, ) = _tokenOwners.at(index);
        return tokenId;
    }
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");
        require(_msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );
        _approve(to, tokenId);
    }
    function getApproved(uint256 tokenId) public view override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");
        return _tokenApprovals[tokenId];
    }
    function setApprovalForAll(address operator, bool approved) public virtual override {
        require(operator != _msgSender(), "ERC721: approve to caller");
        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }
    function isApprovedForAll(address owner, address operator) public view override returns (bool) {
        return _operatorApprovals[owner][operator];
    }
    function transferFrom(address from, address to, uint256 tokenId) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _transfer(from, to, tokenId);
    }
    function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
    }
    function _safeTransfer(address from, address to, uint256 tokenId, bytes memory _data) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }
    function _exists(uint256 tokenId) internal view returns (bool) {
        return _tokenOwners.contains(tokenId);
    }
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view returns (bool) {
        require(_exists(tokenId), "ERC721: operator query for nonexistent token");
        address owner = ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
    }
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }
    function _safeMint(address to, uint256 tokenId, bytes memory _data) internal virtual {
        _mint(to, tokenId);
        require(_checkOnERC721Received(address(0), to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");
        _beforeTokenTransfer(address(0), to, tokenId);
        _holderTokens[to].add(tokenId);
        _tokenOwners.set(tokenId, to);
        emit Transfer(address(0), to, tokenId);
    }
    function _burn(uint256 tokenId) internal virtual {
        address owner = ownerOf(tokenId);
        _beforeTokenTransfer(owner, address(0), tokenId);
        _approve(address(0), tokenId);
        if (bytes(_tokenURIs[tokenId]).length != 0) {
            delete _tokenURIs[tokenId];
        }
        _holderTokens[owner].remove(tokenId);
        _tokenOwners.remove(tokenId);
        emit Transfer(owner, address(0), tokenId);
    }
    function _transfer(address from, address to, uint256 tokenId) internal virtual {
        require(ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
        require(to != address(0), "ERC721: transfer to the zero address");
        _beforeTokenTransfer(from, to, tokenId);
        _approve(address(0), tokenId);
        _holderTokens[from].remove(tokenId);
        _holderTokens[to].add(tokenId);
        _tokenOwners.set(tokenId, to);
        emit Transfer(from, to, tokenId);
    }
    function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {
        require(_exists(tokenId), "ERC721Metadata: URI set of nonexistent token");
        _tokenURIs[tokenId] = _tokenURI;
    }
    function _setBaseURI(string memory baseURI_) internal virtual {
        _baseURI = baseURI_;
    }
    function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data)
        private returns (bool)
    {
        if (!to.isContract()) {
            return true;
        }
        bytes memory returndata = to.functionCall(abi.encodeWithSelector(
            IERC721Receiver(to).onERC721Received.selector,
            _msgSender(),
            from,
            tokenId,
            _data
        ), "ERC721: transfer to non ERC721Receiver implementer");
        bytes4 retval = abi.decode(returndata, (bytes4));
        return (retval == _ERC721_RECEIVED);
    }
    function _approve(address to, uint256 tokenId) private {
        _tokenApprovals[tokenId] = to;
        emit Approval(ownerOf(tokenId), to, tokenId);
    }
    function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual { }
}

contract Pausable is Context {
    event Paused(address account);
    event Unpaused(address account);
    bool private _paused;
    constructor () internal {
        _paused = false;
    }
    function paused() public view returns (bool) {
        return _paused;
    }
    modifier whenNotPaused() {
        require(!_paused, "Pausable: paused");
        _;
    }
    modifier whenPaused() {
        require(_paused, "Pausable: not paused");
        _;
    }
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

abstract contract ERC721Pausable is ERC721, Pausable {
    function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual override {
        super._beforeTokenTransfer(from, to, tokenId);
        require(!paused(), "ERC721Pausable: token transfer while paused");
    }
}

contract Ownable is Context {
    address private _owner;
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }
    function owner() public view returns (address) {
        return _owner;
    }
    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

library TransferHelper {
    function safeApprove(
        address token,
        address to,
        uint256 value
    ) internal {
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');
    }
    function safeTransfer(
        address token,
        address to,
        uint256 value
    ) internal {
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');
    }
    function safeTransferFrom(
        address token,
        address from,
        address to,
        uint256 value
    ) internal {
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');
    }
    function safeTransferETH(address to, uint256 value) internal {
        (bool success, ) = to.call{value: value}(new bytes(0));
        require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
    }
}

contract STAR is ERC721Pausable, AccessControl, Ownable {
    bytes32 public constant UPDATE_TOKEN_URI_ROLE = keccak256('UPDATE_TOKEN_URI_ROLE');
    bytes32 public constant PAUSED_ROLE = keccak256('PAUSED_ROLE');
    uint256 public nextTokenId = 1;
    address public mintFeeAddr;
    uint256 public mintFeeAmount;
    event Burn(address indexed sender, uint256 tokenId);
    event MintFeeAddressTransferred(address indexed previousOwner, address indexed newOwner);
    event SetMintFeeAmount(address indexed seller, uint256 oldMintFeeAmount, uint256 newMintFeeAmount);
    constructor(
        string memory name,
        string memory symbol,
        address _mintFeeAddr,
        uint256 _mintFeeAmount
    ) public ERC721(name, symbol) {
        _setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
        _setupRole(UPDATE_TOKEN_URI_ROLE, _msgSender());
        _setupRole(PAUSED_ROLE, _msgSender());
        mintFeeAddr = _mintFeeAddr;
        mintFeeAmount = _mintFeeAmount;
        emit MintFeeAddressTransferred(address(0), mintFeeAddr);
        emit SetMintFeeAmount(_msgSender(), 0, mintFeeAmount);
    }
    receive() external payable {}
    function mint(address to, string memory _tokenURI) public payable returns (uint256 tokenId) {
        require(msg.value >= mintFeeAmount, 'msg value too low');
        TransferHelper.safeTransferETH(mintFeeAddr, mintFeeAmount);
        tokenId = nextTokenId;
        _mint(to, tokenId);
        nextTokenId++;
        _setTokenURI(tokenId, _tokenURI);
        if (msg.value > mintFeeAmount) TransferHelper.safeTransferETH(msg.sender, msg.value - mintFeeAmount);
    }
    function burn(uint256 tokenId) public {
        require(_isApprovedOrOwner(_msgSender(), tokenId), 'caller is not owner nor approved');
        _burn(tokenId);
        emit Burn(_msgSender(), tokenId);
    }
    function setBaseURI(string memory baseURI) public {
        require(hasRole(UPDATE_TOKEN_URI_ROLE, _msgSender()), 'Must have update token uri role');
        _setBaseURI(baseURI);
    }
    function setTokenURI(uint256 tokenId, string memory tokenURI) public {
        require(hasRole(UPDATE_TOKEN_URI_ROLE, _msgSender()), 'Must have update token uri role');
        _setTokenURI(tokenId, tokenURI);
    }
    function pause() public whenNotPaused {
        require(hasRole(PAUSED_ROLE, _msgSender()), 'Must have pause role');
        _pause();
    }
    function unpause() public whenPaused {
        require(hasRole(PAUSED_ROLE, _msgSender()), 'Must have pause role');
        _unpause();
    }
    function transferMintFeeAddress(address _mintFeeAddr) public {
        require(_msgSender() == mintFeeAddr, 'FORBIDDEN');
        mintFeeAddr = _mintFeeAddr;
        emit MintFeeAddressTransferred(_msgSender(), mintFeeAddr);
    }
    function setMintFeeAmount(uint256 _mintFeeAmount) public onlyOwner {
        require(mintFeeAmount != _mintFeeAmount, 'Not need update');
        emit SetMintFeeAmount(_msgSender(), mintFeeAmount, _mintFeeAmount);
        mintFeeAmount = _mintFeeAmount;
    }
}