/***
 *    ██████╗ ███████╗ ██████╗  ██████╗ 
 *    ██╔══██╗██╔════╝██╔════╝ ██╔═══██╗
 *    ██║  ██║█████╗  ██║  ███╗██║   ██║
 *    ██║  ██║██╔══╝  ██║   ██║██║   ██║
 *    ██████╔╝███████╗╚██████╔╝╚██████╔╝
 *    ╚═════╝ ╚══════╝ ╚═════╝  ╚═════╝ 
 *    
 * https://dego.finance
                                  
* MIT License
* ===========
*
* Copyright (c) 2020 dego
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
*/
// File: @openzeppelin/contracts/math/Math.sol

pragma solidity ^0.5.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}

// File: @openzeppelin/contracts/math/SafeMath.sol

pragma solidity ^0.5.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @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) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @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 sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @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) {
        // 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 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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 mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/GSN/Context.sol

pragma solidity ^0.5.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/ownership/Ownable.sol

pragma solidity ^0.5.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Context {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _owner;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

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

pragma solidity ^0.5.0;

/**
 * @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);
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol

pragma solidity ^0.5.0;


/**
 * @dev Required interface of an ERC721 compliant contract.
 */
contract 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);

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

    /**
     * @dev Returns the owner of the NFT specified by `tokenId`.
     */
    function ownerOf(uint256 tokenId) public view returns (address owner);

    /**
     * @dev Transfers a specific NFT (`tokenId`) from one account (`from`) to
     * another (`to`).
     *
     *
     *
     * Requirements:
     * - `from`, `to` cannot be zero.
     * - `tokenId` must be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this
     * NFT by either {approve} or {setApprovalForAll}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) public;
    /**
     * @dev Transfers a specific NFT (`tokenId`) from one account (`from`) to
     * another (`to`).
     *
     * Requirements:
     * - If the caller is not `from`, it must be approved to move this NFT by
     * either {approve} or {setApprovalForAll}.
     */
    function transferFrom(address from, address to, uint256 tokenId) public;
    function approve(address to, uint256 tokenId) public;
    function getApproved(uint256 tokenId) public view returns (address operator);

    function setApprovalForAll(address operator, bool _approved) public;
    function isApprovedForAll(address owner, address operator) public view returns (bool);


    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory data) public;
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Enumerable.sol

pragma solidity ^0.5.0;


/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
contract IERC721Enumerable is IERC721 {
    function totalSupply() public view returns (uint256);
    function tokenOfOwnerByIndex(address owner, uint256 index) public view returns (uint256 tokenId);

    function tokenByIndex(uint256 index) public view returns (uint256);
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol

pragma solidity ^0.5.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
contract IERC721Receiver {
    /**
     * @notice Handle the receipt of an NFT
     * @dev The ERC721 smart contract calls this function on the recipient
     * after a {IERC721-safeTransferFrom}. This function MUST return the function selector,
     * otherwise the caller will revert the transaction. The selector to be
     * returned can be obtained as `this.onERC721Received.selector`. This
     * function MAY throw to revert and reject the transfer.
     * Note: the ERC721 contract address is always the message sender.
     * @param operator The address which called `safeTransferFrom` function
     * @param from The address which previously owned the token
     * @param tokenId The NFT identifier which is being transferred
     * @param data Additional data with no specified format
     * @return bytes4 `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
     */
    function onERC721Received(address operator, address from, uint256 tokenId, bytes memory data)
    public returns (bytes4);
}

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

pragma solidity ^0.5.5;

/**
 * @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) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Converts an `address` into `address payable`. Note that this is
     * simply a type cast: the actual underlying value is not changed.
     *
     * _Available since v2.4.0._
     */
    function toPayable(address account) internal pure returns (address payable) {
        return address(uint160(account));
    }

    /**
     * @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].
     *
     * _Available since v2.4.0._
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-call-value
        (bool success, ) = recipient.call.value(amount)("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
}

// File: @openzeppelin/contracts/drafts/Counters.sol

pragma solidity ^0.5.0;


/**
 * @title Counters
 * @author Matt Condon (@shrugs)
 * @dev Provides counters that can only be incremented or decremented by one. This can be used e.g. to track the number
 * of elements in a mapping, issuing ERC721 ids, or counting request ids.
 *
 * Include with `using Counters for Counters.Counter;`
 * Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the {SafeMath}
 * overflow check, thereby saving gas. This does assume however correct usage, in that the underlying `_value` is never
 * directly accessed.
 */
library Counters {
    using SafeMath for uint256;

    struct Counter {
        // This variable should never be directly accessed by users of the library: interactions must be restricted to
        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
        // this feature: see https://github.com/ethereum/solidity/issues/4637
        uint256 _value; // default: 0
    }

    function current(Counter storage counter) internal view returns (uint256) {
        return counter._value;
    }

    function increment(Counter storage counter) internal {
        // The {SafeMath} overflow check can be skipped here, see the comment at the top
        counter._value += 1;
    }

    function decrement(Counter storage counter) internal {
        counter._value = counter._value.sub(1);
    }
}

// File: @openzeppelin/contracts/introspection/ERC165.sol

pragma solidity ^0.5.0;


/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts may inherit from this and call {_registerInterface} to declare
 * their support of an interface.
 */
contract ERC165 is IERC165 {
    /*
     * bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
     */
    bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;

    /**
     * @dev Mapping of interface ids to whether or not it's supported.
     */
    mapping(bytes4 => bool) private _supportedInterfaces;

    constructor () internal {
        // Derived contracts need only register support for their own interfaces,
        // we register support for ERC165 itself here
        _registerInterface(_INTERFACE_ID_ERC165);
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     *
     * Time complexity O(1), guaranteed to always use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool) {
        return _supportedInterfaces[interfaceId];
    }

    /**
     * @dev Registers the contract as an implementer of the interface defined by
     * `interfaceId`. Support of the actual ERC165 interface is automatic and
     * registering its interface id is not required.
     *
     * See {IERC165-supportsInterface}.
     *
     * Requirements:
     *
     * - `interfaceId` cannot be the ERC165 invalid interface (`0xffffffff`).
     */
    function _registerInterface(bytes4 interfaceId) internal {
        require(interfaceId != 0xffffffff, "ERC165: invalid interface id");
        _supportedInterfaces[interfaceId] = true;
    }
}

// File: @openzeppelin/contracts/token/ERC721/ERC721.sol

pragma solidity ^0.5.0;








/**
 * @title ERC721 Non-Fungible Token Standard basic implementation
 * @dev see https://eips.ethereum.org/EIPS/eip-721
 */
contract ERC721 is Context, ERC165, IERC721 {
    using SafeMath for uint256;
    using Address for address;
    using Counters for Counters.Counter;

    // Equals to `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
    // which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`
    bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;

    // Mapping from token ID to owner
    mapping (uint256 => address) private _tokenOwner;

    // Mapping from token ID to approved address
    mapping (uint256 => address) private _tokenApprovals;

    // Mapping from owner to number of owned token
    mapping (address => Counters.Counter) private _ownedTokensCount;

    // Mapping from owner to operator approvals
    mapping (address => mapping (address => bool)) private _operatorApprovals;

    /*
     *     bytes4(keccak256('balanceOf(address)')) == 0x70a08231
     *     bytes4(keccak256('ownerOf(uint256)')) == 0x6352211e
     *     bytes4(keccak256('approve(address,uint256)')) == 0x095ea7b3
     *     bytes4(keccak256('getApproved(uint256)')) == 0x081812fc
     *     bytes4(keccak256('setApprovalForAll(address,bool)')) == 0xa22cb465
     *     bytes4(keccak256('isApprovedForAll(address,address)')) == 0xe985e9c5
     *     bytes4(keccak256('transferFrom(address,address,uint256)')) == 0x23b872dd
     *     bytes4(keccak256('safeTransferFrom(address,address,uint256)')) == 0x42842e0e
     *     bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)')) == 0xb88d4fde
     *
     *     => 0x70a08231 ^ 0x6352211e ^ 0x095ea7b3 ^ 0x081812fc ^
     *        0xa22cb465 ^ 0xe985e9c ^ 0x23b872dd ^ 0x42842e0e ^ 0xb88d4fde == 0x80ac58cd
     */
    bytes4 private constant _INTERFACE_ID_ERC721 = 0x80ac58cd;

    constructor () public {
        // register the supported interfaces to conform to ERC721 via ERC165
        _registerInterface(_INTERFACE_ID_ERC721);
    }

    /**
     * @dev Gets the balance of the specified address.
     * @param owner address to query the balance of
     * @return uint256 representing the amount owned by the passed address
     */
    function balanceOf(address owner) public view returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");

        return _ownedTokensCount[owner].current();
    }

    /**
     * @dev Gets the owner of the specified token ID.
     * @param tokenId uint256 ID of the token to query the owner of
     * @return address currently marked as the owner of the given token ID
     */
    function ownerOf(uint256 tokenId) public view returns (address) {
        address owner = _tokenOwner[tokenId];
        require(owner != address(0), "ERC721: owner query for nonexistent token");

        return owner;
    }

    /**
     * @dev Approves another address to transfer the given token ID
     * The zero address indicates there is no approved address.
     * There can only be one approved address per token at a given time.
     * Can only be called by the token owner or an approved operator.
     * @param to address to be approved for the given token ID
     * @param tokenId uint256 ID of the token to be approved
     */
    function approve(address to, uint256 tokenId) public {
        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"
        );

        _tokenApprovals[tokenId] = to;
        emit Approval(owner, to, tokenId);
    }

    /**
     * @dev Gets the approved address for a token ID, or zero if no address set
     * Reverts if the token ID does not exist.
     * @param tokenId uint256 ID of the token to query the approval of
     * @return address currently approved for the given token ID
     */
    function getApproved(uint256 tokenId) public view returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev Sets or unsets the approval of a given operator
     * An operator is allowed to transfer all tokens of the sender on their behalf.
     * @param to operator address to set the approval
     * @param approved representing the status of the approval to be set
     */
    function setApprovalForAll(address to, bool approved) public {
        require(to != _msgSender(), "ERC721: approve to caller");

        _operatorApprovals[_msgSender()][to] = approved;
        emit ApprovalForAll(_msgSender(), to, approved);
    }

    /**
     * @dev Tells whether an operator is approved by a given owner.
     * @param owner owner address which you want to query the approval of
     * @param operator operator address which you want to query the approval of
     * @return bool whether the given operator is approved by the given owner
     */
    function isApprovedForAll(address owner, address operator) public view returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev Transfers the ownership of a given token ID to another address.
     * Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     * Requires the msg.sender to be the owner, approved, or operator.
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     */
    function transferFrom(address from, address to, uint256 tokenId) public {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");

        _transferFrom(from, to, tokenId);
    }

    /**
     * @dev Safely transfers the ownership of a given token ID to another address
     * If the target address is a contract, it must implement {IERC721Receiver-onERC721Received},
     * which is called upon a safe transfer, and return the magic value
     * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
     * the transfer is reverted.
     * Requires the msg.sender to be the owner, approved, or operator
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) public {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev Safely transfers the ownership of a given token ID to another address
     * If the target address is a contract, it must implement {IERC721Receiver-onERC721Received},
     * which is called upon a safe transfer, and return the magic value
     * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
     * the transfer is reverted.
     * Requires the _msgSender() to be the owner, approved, or operator
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes data to send along with a safe transfer check
     */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransferFrom(from, to, tokenId, _data);
    }

    /**
     * @dev Safely transfers the ownership of a given token ID to another address
     * If the target address is a contract, it must implement `onERC721Received`,
     * which is called upon a safe transfer, and return the magic value
     * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
     * the transfer is reverted.
     * Requires the msg.sender to be the owner, approved, or operator
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes data to send along with a safe transfer check
     */
    function _safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) internal {
        _transferFrom(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns whether the specified token exists.
     * @param tokenId uint256 ID of the token to query the existence of
     * @return bool whether the token exists
     */
    function _exists(uint256 tokenId) internal view returns (bool) {
        address owner = _tokenOwner[tokenId];
        return owner != address(0);
    }

    /**
     * @dev Returns whether the given spender can transfer a given token ID.
     * @param spender address of the spender to query
     * @param tokenId uint256 ID of the token to be transferred
     * @return bool whether the msg.sender is approved for the given token ID,
     * is an operator of the owner, or is the owner of the token
     */
    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));
    }

    /**
     * @dev Internal function to safely mint a new token.
     * Reverts if the given token ID already exists.
     * If the target address is a contract, it must implement `onERC721Received`,
     * which is called upon a safe transfer, and return the magic value
     * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
     * the transfer is reverted.
     * @param to The address that will own the minted token
     * @param tokenId uint256 ID of the token to be minted
     */
    function _safeMint(address to, uint256 tokenId) internal {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Internal function to safely mint a new token.
     * Reverts if the given token ID already exists.
     * If the target address is a contract, it must implement `onERC721Received`,
     * which is called upon a safe transfer, and return the magic value
     * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
     * the transfer is reverted.
     * @param to The address that will own the minted token
     * @param tokenId uint256 ID of the token to be minted
     * @param _data bytes data to send along with a safe transfer check
     */
    function _safeMint(address to, uint256 tokenId, bytes memory _data) internal {
        _mint(to, tokenId);
        require(_checkOnERC721Received(address(0), to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Internal function to mint a new token.
     * Reverts if the given token ID already exists.
     * @param to The address that will own the minted token
     * @param tokenId uint256 ID of the token to be minted
     */
    function _mint(address to, uint256 tokenId) internal {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _tokenOwner[tokenId] = to;
        _ownedTokensCount[to].increment();

        emit Transfer(address(0), to, tokenId);
    }

    /**
     * @dev Internal function to burn a specific token.
     * Reverts if the token does not exist.
     * Deprecated, use {_burn} instead.
     * @param owner owner of the token to burn
     * @param tokenId uint256 ID of the token being burned
     */
    function _burn(address owner, uint256 tokenId) internal {
        require(ownerOf(tokenId) == owner, "ERC721: burn of token that is not own");

        _clearApproval(tokenId);

        _ownedTokensCount[owner].decrement();
        _tokenOwner[tokenId] = address(0);

        emit Transfer(owner, address(0), tokenId);
    }

    /**
     * @dev Internal function to burn a specific token.
     * Reverts if the token does not exist.
     * @param tokenId uint256 ID of the token being burned
     */
    function _burn(uint256 tokenId) internal {
        _burn(ownerOf(tokenId), tokenId);
    }

    /**
     * @dev Internal function to transfer ownership of a given token ID to another address.
     * As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     */
    function _transferFrom(address from, address to, uint256 tokenId) internal {
        require(ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
        require(to != address(0), "ERC721: transfer to the zero address");

        _clearApproval(tokenId);

        _ownedTokensCount[from].decrement();
        _ownedTokensCount[to].increment();

        _tokenOwner[tokenId] = to;

        emit Transfer(from, to, tokenId);
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * This is an internal detail of the `ERC721` contract and its use is deprecated.
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data)
        internal returns (bool)
    {
        if (!to.isContract()) {
            return true;
        }
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = to.call(abi.encodeWithSelector(
            IERC721Receiver(to).onERC721Received.selector,
            _msgSender(),
            from,
            tokenId,
            _data
        ));
        if (!success) {
            if (returndata.length > 0) {
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert("ERC721: transfer to non ERC721Receiver implementer");
            }
        } else {
            bytes4 retval = abi.decode(returndata, (bytes4));
            return (retval == _ERC721_RECEIVED);
        }
    }

    /**
     * @dev Private function to clear current approval of a given token ID.
     * @param tokenId uint256 ID of the token to be transferred
     */
    function _clearApproval(uint256 tokenId) private {
        if (_tokenApprovals[tokenId] != address(0)) {
            _tokenApprovals[tokenId] = address(0);
        }
    }
}

// File: @openzeppelin/contracts/token/ERC721/ERC721Enumerable.sol

pragma solidity ^0.5.0;





/**
 * @title ERC-721 Non-Fungible Token with optional enumeration extension logic
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
contract ERC721Enumerable is Context, ERC165, ERC721, IERC721Enumerable {
    // Mapping from owner to list of owned token IDs
    mapping(address => uint256[]) private _ownedTokens;

    // Mapping from token ID to index of the owner tokens list
    mapping(uint256 => uint256) private _ownedTokensIndex;

    // Array with all token ids, used for enumeration
    uint256[] private _allTokens;

    // Mapping from token id to position in the allTokens array
    mapping(uint256 => uint256) private _allTokensIndex;

    /*
     *     bytes4(keccak256('totalSupply()')) == 0x18160ddd
     *     bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) == 0x2f745c59
     *     bytes4(keccak256('tokenByIndex(uint256)')) == 0x4f6ccce7
     *
     *     => 0x18160ddd ^ 0x2f745c59 ^ 0x4f6ccce7 == 0x780e9d63
     */
    bytes4 private constant _INTERFACE_ID_ERC721_ENUMERABLE = 0x780e9d63;

    /**
     * @dev Constructor function.
     */
    constructor () public {
        // register the supported interface to conform to ERC721Enumerable via ERC165
        _registerInterface(_INTERFACE_ID_ERC721_ENUMERABLE);
    }

    /**
     * @dev Gets the token ID at a given index of the tokens list of the requested owner.
     * @param owner address owning the tokens list to be accessed
     * @param index uint256 representing the index to be accessed of the requested tokens list
     * @return uint256 token ID at the given index of the tokens list owned by the requested address
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) public view returns (uint256) {
        require(index < balanceOf(owner), "ERC721Enumerable: owner index out of bounds");
        return _ownedTokens[owner][index];
    }

    /**
     * @dev Gets the total amount of tokens stored by the contract.
     * @return uint256 representing the total amount of tokens
     */
    function totalSupply() public view returns (uint256) {
        return _allTokens.length;
    }

    /**
     * @dev Gets the token ID at a given index of all the tokens in this contract
     * Reverts if the index is greater or equal to the total number of tokens.
     * @param index uint256 representing the index to be accessed of the tokens list
     * @return uint256 token ID at the given index of the tokens list
     */
    function tokenByIndex(uint256 index) public view returns (uint256) {
        require(index < totalSupply(), "ERC721Enumerable: global index out of bounds");
        return _allTokens[index];
    }

    /**
     * @dev Internal function to transfer ownership of a given token ID to another address.
     * As opposed to transferFrom, this imposes no restrictions on msg.sender.
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     */
    function _transferFrom(address from, address to, uint256 tokenId) internal {
        super._transferFrom(from, to, tokenId);

        _removeTokenFromOwnerEnumeration(from, tokenId);

        _addTokenToOwnerEnumeration(to, tokenId);
    }

    /**
     * @dev Internal function to mint a new token.
     * Reverts if the given token ID already exists.
     * @param to address the beneficiary that will own the minted token
     * @param tokenId uint256 ID of the token to be minted
     */
    function _mint(address to, uint256 tokenId) internal {
        super._mint(to, tokenId);

        _addTokenToOwnerEnumeration(to, tokenId);

        _addTokenToAllTokensEnumeration(tokenId);
    }

    /**
     * @dev Internal function to burn a specific token.
     * Reverts if the token does not exist.
     * Deprecated, use {ERC721-_burn} instead.
     * @param owner owner of the token to burn
     * @param tokenId uint256 ID of the token being burned
     */
    function _burn(address owner, uint256 tokenId) internal {
        super._burn(owner, tokenId);

        _removeTokenFromOwnerEnumeration(owner, tokenId);
        // Since tokenId will be deleted, we can clear its slot in _ownedTokensIndex to trigger a gas refund
        _ownedTokensIndex[tokenId] = 0;

        _removeTokenFromAllTokensEnumeration(tokenId);
    }

    /**
     * @dev Gets the list of token IDs of the requested owner.
     * @param owner address owning the tokens
     * @return uint256[] List of token IDs owned by the requested address
     */
    function _tokensOfOwner(address owner) internal view returns (uint256[] storage) {
        return _ownedTokens[owner];
    }

    /**
     * @dev Private function to add a token to this extension's ownership-tracking data structures.
     * @param to address representing the new owner of the given token ID
     * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
     */
    function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
        _ownedTokensIndex[tokenId] = _ownedTokens[to].length;
        _ownedTokens[to].push(tokenId);
    }

    /**
     * @dev Private function to add a token to this extension's token tracking data structures.
     * @param tokenId uint256 ID of the token to be added to the tokens list
     */
    function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
        _allTokensIndex[tokenId] = _allTokens.length;
        _allTokens.push(tokenId);
    }

    /**
     * @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
     * while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
     * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
     * This has O(1) time complexity, but alters the order of the _ownedTokens array.
     * @param from address representing the previous owner of the given token ID
     * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
     */
    function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId) private {
        // To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = _ownedTokens[from].length.sub(1);
        uint256 tokenIndex = _ownedTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary
        if (tokenIndex != lastTokenIndex) {
            uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];

            _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
            _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
        }

        // This also deletes the contents at the last position of the array
        _ownedTokens[from].length--;

        // Note that _ownedTokensIndex[tokenId] hasn't been cleared: it still points to the old slot (now occupied by
        // lastTokenId, or just over the end of the array if the token was the last one).
    }

    /**
     * @dev Private function to remove a token from this extension's token tracking data structures.
     * This has O(1) time complexity, but alters the order of the _allTokens array.
     * @param tokenId uint256 ID of the token to be removed from the tokens list
     */
    function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
        // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = _allTokens.length.sub(1);
        uint256 tokenIndex = _allTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
        // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
        // an 'if' statement (like in _removeTokenFromOwnerEnumeration)
        uint256 lastTokenId = _allTokens[lastTokenIndex];

        _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
        _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index

        // This also deletes the contents at the last position of the array
        _allTokens.length--;
        _allTokensIndex[tokenId] = 0;
    }
}

// File: contracts/interface/IERC20.sol

pragma solidity ^0.5.0;

/**
 * @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: contracts/library/SafeERC20.sol

pragma solidity ^0.5.0;





/**
 * @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: contracts/library/Governance.sol

pragma solidity ^0.5.0;

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: contracts/interface/IPool.sol

pragma solidity ^0.5.0;


interface IPool {
    function totalSupply( ) external view returns (uint256);
    function balanceOf( address player ) external view returns (uint256);
}

// File: contracts/interface/IPlayerBook.sol

pragma solidity ^0.5.0;


interface IPlayerBook {
    function settleReward( address from,uint256 amount ) external returns (uint256);
    function bindRefer( address from,string calldata  affCode )  external returns (bool);
    function hasRefer(address from) external returns(bool);

}

// File: contracts/interface/IGegoFactory.sol

pragma solidity ^0.5.0;

interface IGegoFactory {
    function getGego(uint256 tokenId)
        external view
        returns (
            uint256 grade,
            uint256 quality,
            uint256 degoAmount,
            uint256 createdTime,
            uint256 blockNum,
            uint256 resId,
            address author
        );


    function getQualityBase() external view 
        returns (uint256 );
}

// File: contracts/interface/IGegoToken.sol

pragma solidity ^0.5.0;



contract IGegoToken is IERC721 {
    function mint(address to, uint256 tokenId) external returns (bool) ;
    function burn(uint256 tokenId) external;
}

// File: contracts/reward/NFTReward.sol

pragma solidity ^0.5.0;





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








    
contract NFTReward is IPool,Governance {
    using SafeERC20 for IERC20;
    using SafeMath for uint256;

    IERC20 public _dego = IERC20(0x0);
    IGegoFactory public _gegoFactory = IGegoFactory(0x0);
    IGegoToken public _gegoToken = IGegoToken(0x0);
    address public _playerBook = address(0x0);

    address public _teamWallet = 0x3D0a845C5ef9741De999FC068f70E2048A489F2b;
    address public _rewardPool = 0xEA6dEc98e137a87F78495a8386f7A137408f7722;

    uint256 public constant DURATION = 7 days;
    uint256 public _initReward = 52500 * 1e18;
    uint256 public _startTime =  now + 365 days;
    uint256 public _periodFinish = 0;
    uint256 public _rewardRate = 0;
    uint256 public _lastUpdateTime;
    uint256 public _rewardPerTokenStored;

    uint256 public _teamRewardRate = 500;
    uint256 public _poolRewardRate = 1000;
    uint256 public _baseRate = 10000;
    uint256 public _punishTime = 3 days;

    mapping(address => uint256) public _userRewardPerTokenPaid;
    mapping(address => uint256) public _rewards;
    mapping(address => uint256) public _lastStakedTime;

    bool public _hasStart = false;
    uint256 public _fixRateBase = 100000;
    
    uint256 public _totalWeight;
    mapping(address => uint256) public _weightBalances;
    mapping(uint256 => uint256) public _stakeWeightes;
    mapping(uint256 => uint256) public _stakeBalances;

    uint256 public _totalBalance;
    mapping(address => uint256) public _degoBalances;
    uint256 public _maxStakedDego = 200 * 1e18;

    mapping(address => uint256[]) public _playerGego;
    mapping(uint256 => uint256) public _gegoMapIndex;
    


    event RewardAdded(uint256 reward);
    event StakedGEGO(address indexed user, uint256 amount);
    event WithdrawnGego(address indexed user, uint256 amount);
    event RewardPaid(address indexed user, uint256 reward);
    event NFTReceived(address operator, address from, uint256 tokenId, bytes data);

    constructor(address dego, address gego, address gegoFactory,address playerBook) public {
        _dego = IERC20(dego);
        _gegoToken = IGegoToken(gego);
        _gegoFactory = IGegoFactory(gegoFactory);
        _playerBook = playerBook;
    }
    

    modifier updateReward(address account) {
        _rewardPerTokenStored = rewardPerToken();
        _lastUpdateTime = lastTimeRewardApplicable();
        if (account != address(0)) {
            _rewards[account] = earned(account);
            _userRewardPerTokenPaid[account] = _rewardPerTokenStored;
        }
        _;
    }

    function setMaxStakedDego(uint256 amount) external onlyGovernance{
        _maxStakedDego = amount;
    }

    /* Fee collection for any other token */
    function seize(IERC20 token, uint256 amount) external onlyGovernance{
        require(token != _dego, "reward");
        token.safeTransfer(_governance, amount);
    }
    
    /* Fee collection for any other token */
    function seizeErc721(IERC721 token, uint256 tokenId) external 
    {
        require(token != _gegoToken, "gego stake");
        token.safeTransferFrom(address(this), _governance, tokenId);
    }

    function lastTimeRewardApplicable() public view returns (uint256) {
        return Math.min(block.timestamp, _periodFinish);
    }

    function rewardPerToken() public view returns (uint256) {
        if (totalSupply() == 0) {
            return _rewardPerTokenStored;
        }
        return
            _rewardPerTokenStored.add(
                lastTimeRewardApplicable()
                    .sub(_lastUpdateTime)
                    .mul(_rewardRate)
                    .mul(1e18)
                    .div(totalSupply())
            );
    }

    function earned(address account) public view returns (uint256) {
        return
            balanceOf(account)
                .mul(rewardPerToken().sub(_userRewardPerTokenPaid[account]))
                .div(1e18)
                .add(_rewards[account]);
    }

    
    //the grade is a number between 1-6
    //the quality is a number between 1-10000
    /*
    1   quality	1.1+ 0.1*quality/5000
    2	quality	1.2+ 0.1*(quality-5000)/3000
    3	quality	1.3+ 0.1*(quality-8000/1000
    4	quality	1.4+ 0.2*(quality-9000)/800
    5	quality	1.6+ 0.2*(quality-9800)/180
    6	quality	1.8+ 0.2*(quality-9980)/20
    */

    function getFixRate(uint256 grade,uint256 quality) public pure returns (uint256){

        require(grade > 0 && grade <7, "the gego not dego");

        uint256 unfold = 0;

        if( grade == 1 ){
            unfold = quality*10000/5000;
            return unfold.add(110000);
        }else if( grade == 2){
            unfold = quality.sub(5000)*10000/3000;
            return unfold.add(120000);
        }else if( grade == 3){
            unfold = quality.sub(8000)*10000/1000;
           return unfold.add(130000);
        }else if( grade == 4){
            unfold = quality.sub(9000)*20000/800;
           return unfold.add(140000);
        }else if( grade == 5){
            unfold = quality.sub(9800)*20000/180;
            return unfold.add(160000);
        }else{
            unfold = quality.sub(9980)*20000/20;
            return unfold.add(180000);
        }
    }

    function getStakeInfo( uint256 gegoId ) public view returns ( uint256 stakeRate, uint256 degoAmount){

        uint256 grade;
        uint256 quality;
        uint256 createdTime;
        uint256 blockNum;
        uint256 resId;
        address author;

        (grade, quality, degoAmount, createdTime,blockNum, resId, author) = _gegoFactory.getGego(gegoId);

        require(degoAmount > 0,"the gego not dego");

        stakeRate = getFixRate(grade,quality);
    }

    // stake GEGO 
    function stakeGego(uint256 gegoId, string memory affCode)
        public
        updateReward(msg.sender)
        checkHalve
        checkStart
    {

        uint256[] storage gegoIds = _playerGego[msg.sender];
        if (gegoIds.length == 0) {
            gegoIds.push(0);    
            _gegoMapIndex[0] = 0;
        }
        gegoIds.push(gegoId);
        _gegoMapIndex[gegoId] = gegoIds.length - 1;

        uint256 stakeRate;
        uint256 degoAmount;
        (stakeRate, degoAmount) = getStakeInfo(gegoId);

        uint256 stakedDegoAmount = _degoBalances[msg.sender];
        uint256 stakingDegoAmount = stakedDegoAmount.add(degoAmount) <= _maxStakedDego?degoAmount:_maxStakedDego.sub(stakedDegoAmount);


        if(stakingDegoAmount > 0){
            uint256 stakeWeight = stakeRate.mul(stakingDegoAmount).div(_fixRateBase);
            _degoBalances[msg.sender] = _degoBalances[msg.sender].add(stakingDegoAmount);

            _weightBalances[msg.sender] = _weightBalances[msg.sender].add(stakeWeight);

            _stakeBalances[gegoId] = stakingDegoAmount;
            _stakeWeightes[gegoId] = stakeWeight;
            
            _totalBalance = _totalBalance.add(stakingDegoAmount);
            _totalWeight = _totalWeight.add(stakeWeight);
        }

        _gegoToken.safeTransferFrom(msg.sender, address(this), gegoId);

        if (!IPlayerBook(_playerBook).hasRefer(msg.sender)) {
            IPlayerBook(_playerBook).bindRefer(msg.sender, affCode);
        }
        _lastStakedTime[msg.sender] = now;
        emit StakedGEGO(msg.sender, gegoId);
        
    }
    
    function onERC721Received(address operator, address from, uint256 tokenId, bytes memory data) public returns (bytes4) {
        if(_hasStart == false) {
            return 0;
        }

        emit NFTReceived(operator, from, tokenId, data);
        return bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"));
    }

    function withdrawGego(uint256 gegoId)
        public
        updateReward(msg.sender)
        checkHalve
        checkStart
    {
        require(gegoId > 0, "the gegoId error");
        
        uint256[] memory gegoIds = _playerGego[msg.sender];
        uint256 gegoIndex = _gegoMapIndex[gegoId];
        
        require(gegoIds[gegoIndex] == gegoId, "not gegoId owner");

        uint256 gegoArrayLength = gegoIds.length-1;
        uint256 tailId = gegoIds[gegoArrayLength];

        _playerGego[msg.sender][gegoIndex] = tailId;
        _playerGego[msg.sender][gegoArrayLength] = 0;
        _playerGego[msg.sender].length--;
        _gegoMapIndex[tailId] = gegoIndex;
        _gegoMapIndex[gegoId] = 0;

        uint256 stakeWeight = _stakeWeightes[gegoId];
        _weightBalances[msg.sender] = _weightBalances[msg.sender].sub(stakeWeight);
        _totalWeight = _totalWeight.sub(stakeWeight);

        uint256 stakeBalance = _stakeBalances[gegoId];
        _degoBalances[msg.sender] = _degoBalances[msg.sender].sub(stakeBalance);
        _totalBalance = _totalBalance.sub(stakeBalance);



        _gegoToken.safeTransferFrom(address(this), msg.sender, gegoId);

        _stakeBalances[gegoId] = 0;
        _stakeWeightes[gegoId] = 0;

        emit WithdrawnGego(msg.sender, gegoId);
    }

    function withdraw()
        public
        checkStart
    {

        uint256[] memory gegoId = _playerGego[msg.sender];
        for (uint8 index = 1; index < gegoId.length; index++) {
            if (gegoId[index] > 0) {
                withdrawGego(gegoId[index]);
            }
        }
    }

    function getPlayerIds( address account ) public view returns( uint256[] memory gegoId )
    {
        gegoId = _playerGego[account];
    }

    function exit() external {
        withdraw();
        getReward();
    }

    function getReward() public updateReward(msg.sender) checkHalve checkStart {
        uint256 reward = earned(msg.sender);
        if (reward > 0) {
            _rewards[msg.sender] = 0;

            uint256 fee = IPlayerBook(_playerBook).settleReward(msg.sender, reward);
            if(fee > 0){
                _dego.safeTransfer(_playerBook, fee);
            }
            
            uint256 teamReward = reward.mul(_teamRewardRate).div(_baseRate);
            if(teamReward>0){
                _dego.safeTransfer(_teamWallet, teamReward);
            }
            uint256 leftReward = reward.sub(fee).sub(teamReward);
            uint256 poolReward = 0;

            //withdraw time check

            if(now  < (_lastStakedTime[msg.sender] + _punishTime) ){
                poolReward = leftReward.mul(_poolRewardRate).div(_baseRate);
            }
            if(poolReward>0){
                _dego.safeTransfer(_rewardPool, poolReward);
                leftReward = leftReward.sub(poolReward);
            }

            if(leftReward>0){
                _dego.safeTransfer(msg.sender, leftReward );
            }
      
            emit RewardPaid(msg.sender, leftReward);
        }
    }

    modifier checkHalve() {
        if (block.timestamp >= _periodFinish) {
            _initReward = _initReward.mul(50).div(100);

            _dego.mint(address(this), _initReward);

            _rewardRate = _initReward.div(DURATION);
            _periodFinish = block.timestamp.add(DURATION);
            emit RewardAdded(_initReward);
        }
        _;
    }
    
    modifier checkStart() {
        require(block.timestamp > _startTime, "not start");
        _;
    }

    // set fix time to start reward
    function startNFTReward(uint256 startTime)
        external
        onlyGovernance
        updateReward(address(0))
    {
        require(_hasStart == false, "has started");
        _hasStart = true;
        
        _startTime = startTime;

        _rewardRate = _initReward.div(DURATION); 
        _dego.mint(address(this), _initReward);

        _lastUpdateTime = _startTime;
        _periodFinish = _startTime.add(DURATION);

        emit RewardAdded(_initReward);
    }

    //

    //for extra reward
    function notifyMintAmount(uint256 reward)
        external
        onlyGovernance
        updateReward(address(0))
    {
        // IERC20(_dego).safeTransferFrom(msg.sender, address(this), reward);
        _dego.mint(address(this), reward);
        if (block.timestamp >= _periodFinish) {
            _rewardRate = reward.div(DURATION);
        } else {
            uint256 remaining = _periodFinish.sub(block.timestamp);
            uint256 leftover = remaining.mul(_rewardRate);
            _rewardRate = reward.add(leftover).div(DURATION);
        }
        _lastUpdateTime = block.timestamp;
        _periodFinish = block.timestamp.add(DURATION);
        emit RewardAdded(reward);
    }

    function setTeamRewardRate( uint256 teamRewardRate ) public onlyGovernance {
        _teamRewardRate = teamRewardRate;
    }

    function setPoolRewardRate( uint256  poolRewardRate ) public onlyGovernance{
        _poolRewardRate = poolRewardRate;
    }

    function totalSupply()  public view returns (uint256) {
        return _totalWeight;
    }

    function balanceOf(address account) public view returns (uint256) {
        return _weightBalances[account];
    }
    
    function setWithDrawPunishTime( uint256  punishTime ) public onlyGovernance{
        _punishTime = punishTime;
    }

}

/***
 *    ██████╗ ███████╗ ██████╗  ██████╗ 
 *    ██╔══██╗██╔════╝██╔════╝ ██╔═══██╗
 *    ██║  ██║█████╗  ██║  ███╗██║   ██║
 *    ██║  ██║██╔══╝  ██║   ██║██║   ██║
 *    ██████╔╝███████╗╚██████╔╝╚██████╔╝
 *    ╚═════╝ ╚══════╝ ╚═════╝  ╚═════╝ 
 *    
 * https://dego.finance
                                  
* MIT License
* ===========
*
* Copyright (c) 2020 dego
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
*/
// File: @openzeppelin/contracts/math/SafeMath.sol

pragma solidity ^0.5.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @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) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @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 sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @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) {
        // 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 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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 mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/GSN/Context.sol

pragma solidity ^0.5.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/ownership/Ownable.sol

pragma solidity ^0.5.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Context {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _owner;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: contracts/library/NameFilter.sol

pragma solidity ^0.5.0;

library NameFilter {
    /**
     * @dev filters name strings
     * -converts uppercase to lower case.  
     * -makes sure it does not start/end with a space
     * -makes sure it does not contain multiple spaces in a row
     * -cannot be only numbers
     * -cannot start with 0x 
     * -restricts characters to A-Z, a-z, 0-9, and space.
     * @return reprocessed string in bytes32 format
     */
    function nameFilter(string memory _input)
        internal
        pure
        returns(bytes32)
    {
        bytes memory _temp = bytes(_input);
        uint256 _length = _temp.length;
        
        //sorry limited to 32 characters
        require (_length <= 32 && _length > 0, "string must be between 1 and 32 characters");
        // make sure first two characters are not 0x
        if (_temp[0] == 0x30)
        {
            require(_temp[1] != 0x78, "string cannot start with 0x");
            require(_temp[1] != 0x58, "string cannot start with 0X");
        }
        
        // create a bool to track if we have a non number character
        bool _hasNonNumber;
        
        // convert & check
        for (uint256 i = 0; i < _length; i++)
        {
            // if its uppercase A-Z
            if (_temp[i] > 0x40 && _temp[i] < 0x5b)
            {
                // convert to lower case a-z
                _temp[i] = byte(uint8(_temp[i]) + 32);
                
                // we have a non number
                if (_hasNonNumber == false)
                    _hasNonNumber = true;
            } else {
                require
                (
                    // OR lowercase a-z
                    (_temp[i] > 0x60 && _temp[i] < 0x7b) ||
                    // or 0-9
                    (_temp[i] > 0x2f && _temp[i] < 0x3a),
                    "string contains invalid characters"
                );
                
                // see if we have a character other than a number
                if (_hasNonNumber == false && (_temp[i] < 0x30 || _temp[i] > 0x39))
                    _hasNonNumber = true;    
            }
        }
        
        require(_hasNonNumber == true, "string cannot be only numbers");
        
        bytes32 _ret;
        assembly {
            _ret := mload(add(_temp, 32))
        }
        return (_ret);
    }
}

// File: contracts/interface/IERC20.sol

pragma solidity ^0.5.0;

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

pragma solidity ^0.5.5;

/**
 * @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) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Converts an `address` into `address payable`. Note that this is
     * simply a type cast: the actual underlying value is not changed.
     *
     * _Available since v2.4.0._
     */
    function toPayable(address account) internal pure returns (address payable) {
        return address(uint160(account));
    }

    /**
     * @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].
     *
     * _Available since v2.4.0._
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-call-value
        (bool success, ) = recipient.call.value(amount)("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
}

// File: contracts/library/SafeERC20.sol

pragma solidity ^0.5.0;





/**
 * @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: contracts/library/Governance.sol

pragma solidity ^0.5.0;

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: contracts/interface/IPlayerBook.sol

pragma solidity ^0.5.0;


interface IPlayerBook {
    function settleReward( address from,uint256 amount ) external returns (uint256);
    function bindRefer( address from,string calldata  affCode )  external returns (bool);
    function hasRefer(address from) external returns(bool);

}

// File: contracts/referral/PlayerBook.sol

pragma solidity ^0.5.0;







contract PlayerBook is Governance, IPlayerBook {
    using NameFilter for string;
    using SafeMath for uint256;
    using SafeERC20 for IERC20;
 
    // register pools       
    mapping (address => bool) public _pools;

    // (addr => pID) returns player id by address
    mapping (address => uint256) public _pIDxAddr;   
    // (name => pID) returns player id by name      
    mapping (bytes32 => uint256) public _pIDxName;    
    // (pID => data) player data     
    mapping (uint256 => Player) public _plyr;      
    // (pID => name => bool) list of names a player owns.  (used so you can change your display name amoungst any name you own)        
    mapping (uint256 => mapping (bytes32 => bool)) public _plyrNames; 
  
    // the  of refrerrals
    uint256 public _totalReferReward;         
    // total number of players
    uint256 public _pID;      
    // total register name count
    uint256 public _totalRegisterCount = 0;

    // the direct refer's reward rate
    uint256 public _refer1RewardRate = 700; //7%
    // the second direct refer's reward rate
    uint256 public _refer2RewardRate = 300; //3%
    // base rate
    uint256 public _baseRate = 10000;

    // base price to register a name
    uint256 public _registrationBaseFee = 100 finney;     
    // register fee count step
    uint256 public _registrationStep = 100;
    // add base price for one step
    uint256 public _stepFee = 100 finney;     

    bytes32 public _defaulRefer ="dego";

    address payable public _teamWallet = 0x3D0a845C5ef9741De999FC068f70E2048A489F2b;
  
    IERC20 public _dego = IERC20(0x0);
   
    struct Player {
        address addr;
        bytes32 name;
        uint8 nameCount;
        uint256 laff;
        uint256 amount;
        uint256 rreward;
        uint256 allReward;
        uint256 lv1Count;
        uint256 lv2Count;
    }

    event eveClaim(uint256 pID, address addr, uint256 reward, uint256 balance );
    event eveBindRefer(uint256 pID, address addr, bytes32 name, uint256 affID, address affAddr, bytes32 affName);
    event eveDefaultPlayer(uint256 pID, address addr, bytes32 name);      
    event eveNewName(uint256 pID, address addr, bytes32 name, uint256 affID, address affAddr, bytes32 affName, uint256 balance  );
    event eveSettle(uint256 pID, uint256 affID, uint256 aff_affID, uint256 affReward, uint256 aff_affReward, uint256 amount);
    event eveAddPool(address addr);
    event eveRemovePool(address addr);


    constructor()
        public
    {
        _pID = 0;
        _totalReferReward = 0;
        addDefaultPlayer(_teamWallet,_defaulRefer);
    }

    /**
     * check address
     */
    modifier validAddress( address addr ) {
        require(addr != address(0x0));
        _;
    }

    /**
     * check pool
     */
    modifier isRegisteredPool(){
        require(_pools[msg.sender],"invalid pool address!");
        _;
    }

    /**
     * contract dego balances
     */
    function balances()
        public
        view
        returns(uint256)
    {
        return (_dego.balanceOf(address(this)));
    }

    // only function for creating additional rewards from dust
    function seize(IERC20 asset) external returns (uint256 balance) {
        require(address(_dego) != address(asset), "forbbiden dego");

        balance = asset.balanceOf(address(this));
        asset.safeTransfer(_teamWallet, balance);
    }

    // get register fee 
    function seizeEth() external  {
        uint256 _currentBalance =  address(this).balance;
        _teamWallet.transfer(_currentBalance);
    }
    
    /**
     * revert invalid transfer action
     */
    function() external payable {
        revert();
    }


    /**
     * registe a pool
     */
    function addPool(address poolAddr)
        onlyGovernance
        public
    {
        require( !_pools[poolAddr], "derp, that pool already been registered");

        _pools[poolAddr] = true;

        emit eveAddPool(poolAddr);
    }
    
    /**
     * remove a pool
     */
    function removePool(address poolAddr)
        onlyGovernance
        public
    {
        require( _pools[poolAddr], "derp, that pool must be registered");

        _pools[poolAddr] = false;

        emit eveRemovePool(poolAddr);
    }

    /**
     * resolve the refer's reward from a player 
     */
    function settleReward(address from, uint256 amount)
        isRegisteredPool()
        validAddress(from)    
        external
        returns (uint256)
    {
         // set up our tx event data and determine if player is new or not
        _determinePID(from);

        uint256 pID = _pIDxAddr[from];
        uint256 affID = _plyr[pID].laff;
        
        if(affID <= 0 ){
            affID = _pIDxName[_defaulRefer];
            _plyr[pID].laff = affID;
        }

        if(amount <= 0){
            return 0;
        }

        uint256 fee = 0;

        // father
        uint256 affReward = (amount.mul(_refer1RewardRate)).div(_baseRate);
        _plyr[affID].rreward = _plyr[affID].rreward.add(affReward);
        _totalReferReward = _totalReferReward.add(affReward);
        fee = fee.add(affReward);


        // grandfather
        uint256 aff_affID = _plyr[affID].laff;
        uint256 aff_affReward = amount.mul(_refer2RewardRate).div(_baseRate);
        if(aff_affID <= 0){
            aff_affID = _pIDxName[_defaulRefer];
        }
        _plyr[aff_affID].rreward = _plyr[aff_affID].rreward.add(aff_affReward);
        _totalReferReward= _totalReferReward.add(aff_affReward);

        _plyr[pID].amount = _plyr[pID].amount.add( amount);

        fee = fee.add(aff_affReward);
       
        emit eveSettle( pID,affID,aff_affID,affReward,aff_affReward,amount);

        return fee;
    }

    /**
     * claim all of the refer reward.
     */
    function claim()
        public
    {
        address addr = msg.sender;
        uint256 pid = _pIDxAddr[addr];
        uint256 reward = _plyr[pid].rreward;

        require(reward > 0,"only have reward");
        
        //reset
        _plyr[pid].allReward = _plyr[pid].allReward.add(reward);
        _plyr[pid].rreward = 0;

        //get reward
        _dego.safeTransfer(addr, reward);
        
        // fire event
        emit eveClaim(_pIDxAddr[addr], addr, reward, balances());
    }


    /**
     * check name string
     */
    function checkIfNameValid(string memory nameStr)
        public
        view
        returns(bool)
    {
        bytes32 name = nameStr.nameFilter();
        if (_pIDxName[name] == 0)
            return (true);
        else 
            return (false);
    }
    
    /**
     * @dev add a default player
     */
    function addDefaultPlayer(address addr, bytes32 name)
        private
    {        
        _pID++;

        _plyr[_pID].addr = addr;
        _plyr[_pID].name = name;
        _plyr[_pID].nameCount = 1;
        _pIDxAddr[addr] = _pID;
        _pIDxName[name] = _pID;
        _plyrNames[_pID][name] = true;

        //fire event
        emit eveDefaultPlayer(_pID,addr,name);        
    }
    
    /**
     * @dev set refer reward rate
     */
    function setReferRewardRate(uint256 refer1Rate, uint256 refer2Rate ) public  
        onlyGovernance
    {
        _refer1RewardRate = refer1Rate;
        _refer2RewardRate = refer2Rate;
    }

    /**
     * @dev set registration step count
     */
    function setRegistrationStep(uint256 registrationStep) public  
        onlyGovernance
    {
        _registrationStep = registrationStep;
    }

    /**
     * @dev set dego contract address
     */
    function setDegoContract(address dego)  public  
        onlyGovernance{
        _dego = IERC20(dego);
    }


    /**
     * @dev registers a name.  UI will always display the last name you registered.
     * but you will still own all previously registered names to use as affiliate 
     * links.
     * - must pay a registration fee.
     * - name must be unique
     * - names will be converted to lowercase
     * - cannot be only numbers
     * - cannot start with 0x 
     * - name must be at least 1 char
     * - max length of 32 characters long
     * - allowed characters: a-z, 0-9
     * -functionhash- 0x921dec21 (using ID for affiliate)
     * -functionhash- 0x3ddd4698 (using address for affiliate)
     * -functionhash- 0x685ffd83 (using name for affiliate)
     * @param nameString players desired name
     * @param affCode affiliate name of who refered you
     * (this might cost a lot of gas)
     */

    function registerNameXName(string memory nameString, string memory affCode)
        public
        payable 
    {

        // make sure name fees paid
        require (msg.value >= this.getRegistrationFee(), "umm.....  you have to pay the name fee");

        // filter name + condition checks
        bytes32 name = NameFilter.nameFilter(nameString);
        // if names already has been used
        require(_pIDxName[name] == 0, "sorry that names already taken");

        // set up address 
        address addr = msg.sender;
         // set up our tx event data and determine if player is new or not
        _determinePID(addr);
        // fetch player id
        uint256 pID = _pIDxAddr[addr];
        // if names already has been used
        require(_plyrNames[pID][name] == false, "sorry that names already taken");

        // add name to player profile, registry, and name book
        _plyrNames[pID][name] = true;
        _pIDxName[name] = pID;   
        _plyr[pID].name = name;
        _plyr[pID].nameCount++;

        _totalRegisterCount++;


        //try bind a refer
        if(_plyr[pID].laff == 0){

            bytes memory tempCode = bytes(affCode);
            bytes32 affName = 0x0;
            if (tempCode.length >= 0) {
                assembly {
                    affName := mload(add(tempCode, 32))
                }
            }

            _bindRefer(addr,affName);
        }
        uint256 affID = _plyr[pID].laff;

        // fire event
        emit eveNewName(pID, addr, name, affID, _plyr[affID].addr, _plyr[affID].name, _registrationBaseFee );
    }
    
    /**
     * @dev bind a refer,if affcode invalid, use default refer
     */  
    function bindRefer( address from, string calldata  affCode )
        isRegisteredPool()
        external
        returns (bool)
    {

        bytes memory tempCode = bytes(affCode);
        bytes32 affName = 0x0;
        if (tempCode.length >= 0) {
            assembly {
                affName := mload(add(tempCode, 32))
            }
        }

        return _bindRefer(from, affName);
    }


    /**
     * @dev bind a refer,if affcode invalid, use default refer
     */  
    function _bindRefer( address from, bytes32  name )
        validAddress(msg.sender)    
        validAddress(from)  
        private
        returns (bool)
    {
        // set up our tx event data and determine if player is new or not
        _determinePID(from);

        // fetch player id
        uint256 pID = _pIDxAddr[from];
        if( _plyr[pID].laff != 0){
            return false;
        }

        if (_pIDxName[name] == 0){
            //unregister name 
            name = _defaulRefer;
        }
      
        uint256 affID = _pIDxName[name];
        if( affID == pID){
            affID = _pIDxName[_defaulRefer];
        }
       
        _plyr[pID].laff = affID;

        //lvcount
        _plyr[affID].lv1Count++;
        uint256 aff_affID = _plyr[affID].laff;
        if(aff_affID != 0 ){
            _plyr[aff_affID].lv2Count++;
        }
        
        // fire event
        emit eveBindRefer(pID, from, name, affID, _plyr[affID].addr, _plyr[affID].name);

        return true;
    }
    
    //
    function _determinePID(address addr)
        private
        returns (bool)
    {
        if (_pIDxAddr[addr] == 0)
        {
            _pID++;
            _pIDxAddr[addr] = _pID;
            _plyr[_pID].addr = addr;
            
            // set the new player bool to true
            return (true);
        } else {
            return (false);
        }
    }
    
    function hasRefer(address from) 
        isRegisteredPool()
        external 
        returns(bool) 
    {
        _determinePID(from);
        uint256 pID =  _pIDxAddr[from];
        return (_plyr[pID].laff > 0);
    }

    
    function getPlayerName(address from)
        external
        view
        returns (bytes32)
    {
        uint256 pID =  _pIDxAddr[from];
        if(_pID==0){
            return "";
        }
        return (_plyr[pID].name);
    }

    function getPlayerLaffName(address from)
        external
        view
        returns (bytes32)
    {
        uint256 pID =  _pIDxAddr[from];
        if(_pID==0){
             return "";
        }

        uint256 aID=_plyr[pID].laff;
        if( aID== 0){
            return "";
        }

        return (_plyr[aID].name);
    }

    function getPlayerInfo(address from)
        external
        view
        returns (uint256,uint256,uint256,uint256)
    {
        uint256 pID = _pIDxAddr[from];
        if(_pID==0){
             return (0,0,0,0);
        }
        return (_plyr[pID].rreward,_plyr[pID].allReward,_plyr[pID].lv1Count,_plyr[pID].lv2Count);
    }

    function getTotalReferReward()
        external
        view
        returns (uint256)
    {
        return(_totalReferReward);
    }

    function getRegistrationFee()
        external
        view
        returns (uint256)
    {
        if( _totalRegisterCount <_registrationStep || _registrationStep == 0){
            return _registrationBaseFee;
        }
        else{
            uint256 step = _totalRegisterCount.div(_registrationStep);
            return _registrationBaseFee.add(step.mul(_stepFee));
        }
    }
}

/***
 *    ██████╗ ███████╗ ██████╗  ██████╗ 
 *    ██╔══██╗██╔════╝██╔════╝ ██╔═══██╗
 *    ██║  ██║█████╗  ██║  ███╗██║   ██║
 *    ██║  ██║██╔══╝  ██║   ██║██║   ██║
 *    ██████╔╝███████╗╚██████╔╝╚██████╔╝
 *    ╚═════╝ ╚══════╝ ╚═════╝  ╚═════╝ 
 *    
 * https://dego.finance
                                  
* MIT License
* ===========
*
* Copyright (c) 2020 dego
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
*/
// File: @openzeppelin/contracts/math/SafeMath.sol

pragma solidity ^0.5.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @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) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @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 sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @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) {
        // 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 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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 mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.5.0;

/**
 * @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);

    /**
     * @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: @openzeppelin/contracts/token/ERC20/ERC20Detailed.sol

pragma solidity ^0.5.0;


/**
 * @dev Optional functions from the ERC20 standard.
 */
contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for `name`, `symbol`, and `decimals`. All three of
     * these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

// File: contracts/library/Governance.sol

pragma solidity ^0.5.5;

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: contracts/token/DegoToken.sol

pragma solidity ^0.5.5;




/// @title DegoToken Contract

contract DegoToken is Governance, ERC20Detailed{

    using SafeMath for uint256;

    //events
    event eveSetRate(uint256 burn_rate, uint256 reward_rate);
    event eveRewardPool(address rewardPool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Mint(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    // for minters
    mapping (address => bool) public _minters;

    //token base data
    uint256 internal _totalSupply;
    mapping(address => uint256) public _balances;
    mapping (address => mapping (address => uint256)) public _allowances;

    /// Constant token specific fields
    uint256 public  _maxSupply = 0;

    ///
    bool public _openTransfer = false;

    // hardcode limit rate
    uint256 public constant _maxGovernValueRate = 2000;//2000/10000
    uint256 public constant _minGovernValueRate = 10;  //10/10000
    uint256 public constant _rateBase = 10000; 

    // additional variables for use if transaction fees ever became necessary
    uint256 public  _burnRate = 250;       
    uint256 public  _rewardRate = 250;   

    uint256 public _totalBurnToken = 0;
    uint256 public _totalRewardToken = 0;

    //todo reward pool!
    address public _rewardPool = 0xEA6dEc98e137a87F78495a8386f7A137408f7722;
    //todo burn pool!
    address public _burnPool = 0x6666666666666666666666666666666666666666;

    /**
    * @dev set the token transfer switch
    */
    function enableOpenTransfer() public onlyGovernance  
    {
        _openTransfer = true;
    }


    /**
     * CONSTRUCTOR
     *
     * @dev Initialize the Token
     */

    constructor () public ERC20Detailed("dego.finance", "DEGO", 18) {
         _maxSupply = 21000000 * (10**18);
    }


    
    /**
    * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
    * @param spender The address which will spend the funds.
    * @param amount The amount of tokens to be spent.
    */
    function approve(address spender, uint256 amount) external 
    returns (bool) 
    {
        require(msg.sender != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);

        return true;
    }

    /**
    * @dev Function to check the amount of tokens than an owner _allowed to a spender.
    * @param owner address The address which owns the funds.
    * @param spender address The address which will spend the funds.
    * @return A uint256 specifying the amount of tokens still available for the spender.
    */
    function allowance(address owner, address spender) external view 
    returns (uint256) 
    {
        return _allowances[owner][spender];
    }

    /**
    * @dev Gets the balance of the specified address.
    * @param owner The address to query the the balance of.
    * @return An uint256 representing the amount owned by the passed address.
    */
    function balanceOf(address owner) external  view 
    returns (uint256) 
    {
        return _balances[owner];
    }

    /**
    * @dev return the token total supply
    */
    function totalSupply() external view 
    returns (uint256) 
    {
        return _totalSupply;
    }

    /**
    * @dev for mint function
    */
    function mint(address account, uint256 amount) external 
    {
        require(account != address(0), "ERC20: mint to the zero address");
        require(_minters[msg.sender], "!minter");

        uint256 curMintSupply = _totalSupply.add(_totalBurnToken);
        uint256 newMintSupply = curMintSupply.add(amount);
        require( newMintSupply <= _maxSupply,"supply is max!");
      
        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);

        emit Mint(address(0), account, amount);
        emit Transfer(address(0), account, amount);
    }

    function addMinter(address _minter) public onlyGovernance 
    {
        _minters[_minter] = true;
    }
    
    function removeMinter(address _minter) public onlyGovernance 
    {
        _minters[_minter] = false;
    }
    

    function() external payable {
        revert();
    }

    /**
    * @dev for govern value
    */
    function setRate(uint256 burn_rate, uint256 reward_rate) public 
        onlyGovernance 
    {
        
        require(_maxGovernValueRate >= burn_rate && burn_rate >= _minGovernValueRate,"invalid burn rate");
        require(_maxGovernValueRate >= reward_rate && reward_rate >= _minGovernValueRate,"invalid reward rate");

        _burnRate = burn_rate;
        _rewardRate = reward_rate;

        emit eveSetRate(burn_rate, reward_rate);
    }


    /**
    * @dev for set reward
    */
    function setRewardPool(address rewardPool) public 
        onlyGovernance 
    {
        require(rewardPool != address(0x0));

        _rewardPool = rewardPool;

        emit eveRewardPool(_rewardPool);
    }
    /**
    * @dev transfer token for a specified address
    * @param to The address to transfer to.
    * @param value The amount to be transferred.
    */
   function transfer(address to, uint256 value) external 
   returns (bool)  
   {
        return _transfer(msg.sender,to,value);
    }

    /**
    * @dev Transfer tokens from one address to another
    * @param from address The address which you want to send tokens from
    * @param to address The address which you want to transfer to
    * @param value uint256 the amount of tokens to be transferred
    */
    function transferFrom(address from, address to, uint256 value) external 
    returns (bool) 
    {
        uint256 allow = _allowances[from][msg.sender];
        _allowances[from][msg.sender] = allow.sub(value);
        
        return _transfer(from,to,value);
    }

 

    /**
    * @dev Transfer tokens with fee
    * @param from address The address which you want to send tokens from
    * @param to address The address which you want to transfer to
    * @param value uint256s the amount of tokens to be transferred
    */
    function _transfer(address from, address to, uint256 value) internal 
    returns (bool) 
    {
        // :)
        require(_openTransfer || from == governance, "transfer closed");

        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        uint256 sendAmount = value;
        uint256 burnFee = (value.mul(_burnRate)).div(_rateBase);
        if (burnFee > 0) {
            //to burn
            _balances[_burnPool] = _balances[_burnPool].add(burnFee);
            _totalSupply = _totalSupply.sub(burnFee);
            sendAmount = sendAmount.sub(burnFee);

            _totalBurnToken = _totalBurnToken.add(burnFee);

            emit Transfer(from, _burnPool, burnFee);
        }

        uint256 rewardFee = (value.mul(_rewardRate)).div(_rateBase);
        if (rewardFee > 0) {
           //to reward
            _balances[_rewardPool] = _balances[_rewardPool].add(rewardFee);
            sendAmount = sendAmount.sub(rewardFee);

            _totalRewardToken = _totalRewardToken.add(rewardFee);

            emit Transfer(from, _rewardPool, rewardFee);
        }

        _balances[from] = _balances[from].sub(value);
        _balances[to] = _balances[to].add(sendAmount);

        emit Transfer(from, to, sendAmount);

        return true;
    }
}