// File: TroyNFTMintProxy.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <=0.8.4;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";

import "../interface/ITroyNFTFactory.sol";
import "../interface/IGegoRuleProxy.sol";
import "../library/Governance.sol";
import "../interface/IERC20.sol";
import "../library/SafeERC20.sol";

contract TroyNFTMintProxy is Governance, IGegoRuleProxy{
    using Address for address;
    using SafeMath for uint256;
    using SafeERC20 for IERC20;
    
    uint256 public _qualityBase = 10000;
    uint256 public _maxGrade = 6;
    uint256 public _maxGradeLong = 20;
    uint256 public _maxTLevel = 6;


    struct RuleData{
        uint256 minMintAmount;
        uint256 maxMintAmount;
        uint256 costErc20Amount;
        address mintErc20;
        address costErc20;
        uint256 minBurnTime;
        uint256 tLevel;
        bool canMintMaxGrade;
        bool canMintMaxTLevel;
    }

    address public _costErc20Pool = address(0x0);
    ITroyNFTFactory public _factory = ITroyNFTFactory(address(0));

    event eSetRuleData(uint256 ruleId, uint256 minMintAmount, uint256 maxMintAmount, uint256 costErc20Amount, address mintErc20, address costErc20, bool canMintMaxGrade,bool canMintMaxTLevel,uint256 minBurnTime);

    mapping(uint256 => RuleData) public _ruleData;
    mapping(uint256 => bool) public _ruleSwitch;
    
    constructor(address costErc20Pool) public {
        _costErc20Pool = costErc20Pool;
    }

    function setQualityBase(uint256 val) public onlyGovernance{
        _qualityBase =  val;
    }

    function setMaxGrade(uint256 val) public onlyGovernance{
        _maxGrade =  val;
    }

    function setMaxTLevel(uint256 val) public onlyGovernance{
        _maxTLevel =  val;
    }

    function setMaxGradeLong(uint256 val) public onlyGovernance{
        _maxGradeLong =  val;
    }

    function setRuleData(
        uint256 ruleId, 
        uint256 minMintAmount, 
        uint256 maxMintAmount, 
        uint256 costErc20Amount, 
        address mintErc20, 
        address costErc20,
        uint256 minBurnTime,
        uint256 tLevel,
        bool canMintMaxGrade,
        bool canMintMaxTLevel
         )
        public
        onlyGovernance
    {
        
        _ruleData[ruleId].minMintAmount = minMintAmount;
        _ruleData[ruleId].maxMintAmount = maxMintAmount;
        _ruleData[ruleId].costErc20Amount = costErc20Amount;
        _ruleData[ruleId].mintErc20 = mintErc20;
        _ruleData[ruleId].costErc20 = costErc20;
        _ruleData[ruleId].minBurnTime = minBurnTime;
        _ruleData[ruleId].canMintMaxGrade = canMintMaxGrade;
        _ruleData[ruleId].canMintMaxTLevel = canMintMaxTLevel;
        _ruleData[ruleId].tLevel = tLevel;

        _ruleSwitch[ruleId] = true;

        emit eSetRuleData( ruleId,  minMintAmount,  maxMintAmount,  costErc20Amount,  mintErc20,  costErc20, canMintMaxGrade, canMintMaxTLevel,minBurnTime);
    }


     function enableRule( uint256 ruleId,bool enable )         
        public
        onlyGovernance 
     {
        _ruleSwitch[ruleId] = enable;
     }

     function setFactory( address factory )         
        public
        onlyGovernance 
     {
        _factory = ITroyNFTFactory(factory);
     }

    function cost( MintParams calldata params) external override returns (  uint256 mintAmount,address mintErc20 ){
        require( _factory == ITroyNFTFactory(msg.sender)," invalid factory caller" );
       (mintAmount,mintErc20) =  _cost(params);
    } 

    function destroy(  address owner, ITroyNFT.Gego calldata gego) external override {
        require( _factory == ITroyNFTFactory(msg.sender)," invalid factory caller" );
        
        if( _factory.isRulerProxyContract(owner) == false){
            require( (block.timestamp - gego.createdTime) >=  gego.lockedDays * 86400, "< minBurnTime"  );
        }

        IERC20 erc20 = IERC20(gego.erc20);
        erc20.safeTransfer(owner, gego.amount);
    } 


    function generate( address user , uint256 ruleId, uint256 randomNonce ) external override view returns (  ITroyNFT.Gego memory gego ){
        require( _factory == ITroyNFTFactory(msg.sender) ," invalid factory caller" );
        require(_ruleSwitch[ruleId], " rule is closed ");

        uint256 seed = computerSeed(user);

        gego.quality = seed%_qualityBase;
        gego.grade = getGrade(gego.quality);

        if(gego.grade == _maxGrade && _ruleData[ruleId].canMintMaxGrade == false){
            gego.grade = gego.grade.sub(1);
            gego.quality = gego.quality.sub(_maxGradeLong);
        }
        gego.lockedDays = computeLockDays(user, randomNonce);
        gego.tLevel = _ruleData[ruleId].tLevel;
        randomNonce++;
    } 


    function _cost( MintParams memory params) internal returns (  uint256 mintAmount,address mintErc20 ){
        require( _ruleData[params.ruleId].mintErc20 != address(0x0), "invalid mintErc20 rule !");
        require( _ruleData[params.ruleId].costErc20 != address(0x0), "invalid costErc20 rule !");
        require( params.amount >= _ruleData[params.ruleId].minMintAmount && params.amount <= _ruleData[params.ruleId].maxMintAmount, "invalid mint amount!");

        IERC20 mintIErc20 = IERC20(_ruleData[params.ruleId].mintErc20);
        uint256 balanceBefore = mintIErc20.balanceOf(address(this));
        if(params.amount>0) {
            mintIErc20.transferFrom(params.user, address(this), params.amount);
        }
        
        uint256 balanceEnd = mintIErc20.balanceOf(address(this));

        uint256 costErc20Amount = _ruleData[params.ruleId].costErc20Amount;
        if(costErc20Amount > 0){
            IERC20 costErc20 = IERC20(_ruleData[params.ruleId].costErc20);
            costErc20.transferFrom(params.user, _costErc20Pool, costErc20Amount);
        }

        mintAmount = balanceEnd.sub(balanceBefore);
        mintErc20 = _ruleData[params.ruleId].mintErc20;

    } 

    function getGrade(uint256 quality) public view returns (uint256){
        
        if( quality < _qualityBase.mul(500).div(1000)){
            return 1;
        }else if( _qualityBase.mul(500).div(1000) <= quality && quality <  _qualityBase.mul(800).div(1000)){
            return 2;
        }else if( _qualityBase.mul(800).div(1000) <= quality && quality <  _qualityBase.mul(900).div(1000)){
            return 3;
        }else if( _qualityBase.mul(900).div(1000) <= quality && quality <  _qualityBase.mul(980).div(1000)){
            return 4;
        }else if( _qualityBase.mul(980).div(1000) <= quality && quality <  _qualityBase.mul(998).div(1000)){
            return 5;
        }else{
            return 6;
        }
    }

    function computerSeed( address user ) internal view returns (uint256) {
        // from fomo3D
        uint256 seed = uint256(keccak256(abi.encodePacked(
            //(user.balance).add
            (block.timestamp).add
            (block.difficulty).add
            ((uint256(keccak256(abi.encodePacked(block.coinbase)))) / (block.timestamp)).add
            (block.gaslimit).add
            ((uint256(keccak256(abi.encodePacked(user)))) / (block.timestamp)).add
            (block.number)
            
        )));
        return seed;
    }

    function computeLockDays(address user, uint nonce) internal view returns (uint256) {
        // random from 25 - 45 days
        uint randomnumber = uint(keccak256(abi.encodePacked(block.timestamp, msg.sender, nonce))) % 20;
        randomnumber = randomnumber + 25;
        if(randomnumber < 25) randomnumber = 25;
        if(randomnumber > 45) randomnumber = 45;
        return randomnumber;
    }
}
// File: library/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <=0.8.4;

import "../interface/IERC20.sol";

import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";


/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}
// File: interface/IERC20.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <=0.8.4;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);
    function mint(address account, uint amount) external;
    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}
// File: library/Governance.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <=0.8.4;

contract Governance {

    address public _governance;

    constructor() public {
        _governance = tx.origin;
    }

    event GovernanceTransferred(address indexed previousOwner, address indexed newOwner);

    modifier onlyGovernance {
        require(msg.sender == _governance, "not governance");
        _;
    }

    function setGovernance(address governance)  public  onlyGovernance
    {
        require(governance != address(0), "new governance the zero address");
        emit GovernanceTransferred(_governance, governance);
        _governance = governance;
    }

}
// File: interface/IGegoRuleProxy.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <=0.8.4;

pragma experimental ABIEncoderV2;

import "../interface/ITroyNFT.sol";

interface IGegoRuleProxy  {

    struct Cost721Asset{
        uint256 costErc721Id1;
        uint256 costErc721Id2;
        uint256 costErc721Id3;

        address costErc721Origin;
    }

    struct MintParams{
        address user;
        uint256 amount;
        uint256 ruleId;
    }

    function cost( MintParams calldata params) external returns (
        uint256 mintAmount,
        address mintErc20
    ) ;

    function destroy( address owner, ITroyNFT.Gego calldata gego ) external ;

    function generate( address user,uint256 ruleId, uint256 randomNonce ) external view returns ( ITroyNFT.Gego memory gego );

}
// File: interface/ITroyNFTFactory.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <=0.8.4;

pragma experimental ABIEncoderV2;

import "../interface/ITroyNFT.sol";

interface ITroyNFTFactory {

    function getGego(uint256 tokenId)
        external view
        returns (
            uint256 grade,
            uint256 quality,
            uint256 amount,
            uint256 resBaseId,
            uint256 tLevel,
            uint256 ruleId,
            uint256 nftType,
            address author,
            address erc20,
            uint256 createdTime,
            uint256 blockNum,
            uint256 lockedDays
        );


    function getGegoStruct(uint256 tokenId)
        external view
        returns (ITroyNFT.Gego memory gego);

    function burn(uint256 tokenId) external returns ( bool );
    
    function isRulerProxyContract(address proxy) external view returns ( bool );
}
// File: @openzeppelin/contracts/utils/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is no longer needed starting with Solidity 0.8. The compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    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");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    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");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    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");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: interface/ITroyNFT.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <=0.8.4;

import "@openzeppelin/contracts/token/ERC721/IERC721.sol";

interface ITroyNFT is IERC721 {

    struct Gego {
        uint256 id;
        uint256 grade;
        uint256 quality;
        uint256 amount;
        uint256 resBaseId;
        uint256 tLevel;
        uint256 ruleId;
        uint256 nftType;
        address author;
        address erc20;
        uint256 createdTime;
        uint256 blockNum;
        uint256 lockedDays;
    }
    
    function mint(address to, uint256 tokenId) external returns (bool) ;
    function burn(uint256 tokenId) external;
}
// File: @openzeppelin/contracts/token/ERC721/IERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}