// File: /contracts/RFOXAUCTION.sol



//SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;

import "openzeppelin-solidity/contracts/interfaces/IERC20.sol";
import "openzeppelin-solidity/contracts/utils/math/SafeMath.sol";
import "./utils/OwnerPausable.sol";
import "openzeppelin-solidity/contracts/interfaces/IERC721.sol";
import "openzeppelin-solidity/contracts/interfaces/IERC721Receiver.sol";

contract RFOXAUCTION is OwnerPausable, IERC721Receiver {
  using SafeMath for uint256;

  enum AuctionStatus { Normal, Ended, Canceled }
  struct AuctionInfo {
    address seller;
    address nft;
    uint itemId;
    uint price;
    address bidder;
    uint createdAt;
    uint updatedAt;
    uint start;
    uint end;
    AuctionStatus status;
  }

  struct BidInfo {
    uint auctionId;
    uint itemId;
    uint price;
    address bidder;
    uint bidAt;
  }

  AuctionInfo[] public auctions;
  BidInfo[] public bids;
  uint256 public bidPricePercent;

  mapping(uint256 => uint256[]) public bidsOfAuction;
  mapping(address => uint256[]) public bidsOfUser;

  mapping(address => uint256) public bidCount;
  mapping(address => uint256) public wonCount;

  // Equals to `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
  // which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`

  uint private constant MIN_BID_PRICE_PERCENT = 101;
  uint private constant MAX_BID_PRICE_PERCNET = 120;

  bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;

  event CreateAuction(address indexed sender, uint itemId, uint start, uint end);
  event Bid(address indexed sender, uint auctionId, uint price, uint bidAt);
  event CancelAuction(address indexed sender, uint auctionId);
  event EndAuction(address indexed sender, uint auctionId);
  event SetBidPricePercent(address indexed sender, uint _bidPricePercent);

  constructor (uint256 _bidPricePercent) {
    require(_bidPricePercent >= MIN_BID_PRICE_PERCENT &&
            _bidPricePercent <= MAX_BID_PRICE_PERCNET, "Auction: Invalid Bid Price Percent");

    bidPricePercent = _bidPricePercent;
  }

  modifier validId(uint _auctionId) {
    require(_auctionId < auctions.length, "Auction: Invalid Auction Id");
    _;
  }
  
  modifier validSeller(uint _auctionId) {
    AuctionInfo storage auction = auctions[_auctionId];
    require(auction.seller == _msgSender(), "Auction: Invalid Permission");
    _;
  }

  modifier validWinner(uint _auctionId) {
    AuctionInfo storage auction = auctions[_auctionId];
    require(auction.bidder == _msgSender(), "Auction: Invalid Permission");
    _;
  }

  /**
   * Create a new auction
   *
   * @param _nft address of nft
   * @param _itemId token id of nft
   * @param _price start price
   * @param _start start date
   * @param _end end date
  */
  function createAuction(address _nft, uint _itemId, uint _price,  uint _start, uint _end) external onlyOwner whenNotPaused {
    require(_start < _end, "Auction: Period is not valid");
    IERC721(_nft).safeTransferFrom(_msgSender(), address(this), _itemId);
    AuctionInfo memory newAuction = AuctionInfo(
                                      _msgSender(),
                                      _nft,
                                      _itemId,
                                      _price,
                                      address(0),
                                      block.timestamp,
                                      block.timestamp,
                                      _start,
                                      _end,
                                      AuctionStatus.Normal
                                    );
    auctions.push(newAuction);
    emit CreateAuction(_msgSender(), _itemId, _start, _end);
  }

  /**
   * Bid to an auction
   *
   * @param _auctionId auction id to bid
  */
  function bid(uint _auctionId) external validId(_auctionId) whenNotPaused payable {
    AuctionInfo storage auction = auctions[_auctionId];
    require(_msgSender() != auction.seller, "Auction: Invalid Bidder");
    require(_msgSender() != auction.bidder, "Auction: Invalid Bidder");
    require(block.timestamp >= auction.start, "Auction: Auction is not started");
    require(block.timestamp <= auction.end, "Auction: Auction is Over");
    require(msg.value > auction.price.mul(bidPricePercent).div(100), "Auction: Price is low");
    require(auction.status == AuctionStatus.Normal, "Auction: Bid is not allowed");

    // Require bidder is not highest bidder on another auction
    // require(bidCount[_msgSender()] == 0, "Auction: Bidder can only win 1 shop at a time");

    if (auction.bidder != address(0)) {
      bidCount[auction.bidder] = bidCount[auction.bidder].sub(1);
      (bool success, ) = auction.bidder.call{ value: auction.price}("");
      require(success, 'Auction: unable to send value, recipient may have reverted');
    }
    
    bidCount[_msgSender()] = bidCount[_msgSender()].add(1);

    auction.bidder = _msgSender();
    auction.price = msg.value;
    auction.updatedAt = block.timestamp;

    BidInfo memory newBid = BidInfo(_auctionId, auction.itemId, msg.value, _msgSender(), block.timestamp);
    bids.push(newBid);

    bidsOfAuction[_auctionId].push(bids.length - 1);
    bidsOfUser[_msgSender()].push(bids.length - 1);

    emit Bid(_msgSender(), _auctionId, msg.value, block.timestamp);
  }

  /**
   * Cancel an auction
   *
   * @param _auctionId auction id to cancel
  */
  function cancelAuction(uint _auctionId) external validId(_auctionId) validSeller(_auctionId) whenNotPaused {
    AuctionInfo storage auction = auctions[_auctionId];
    require(auction.start > block.timestamp, "Auction: Not Cancelable");
    require(bidsOfAuction[_auctionId].length == 0, "Auction: There are bids already");
    auction.status = AuctionStatus.Canceled;

    IERC721(auction.nft).safeTransferFrom(address(this), _msgSender(), auction.itemId);
    emit CancelAuction(_msgSender(), _auctionId);
  }

  /**
   * Set percent of price to bid higher than current price
   *
   * @param _bidPricePercent percent
  */
  function setBidPricePercent(uint _bidPricePercent) external onlyOwner {
    require(_bidPricePercent >= MIN_BID_PRICE_PERCENT && _bidPricePercent <= MAX_BID_PRICE_PERCNET, "Invalid Bid Price Percent");
    bidPricePercent = _bidPricePercent;
    emit SetBidPricePercent(_msgSender(), _bidPricePercent);
  }

  /**
   * Return total number of auctions
   *
   * @return number of auctions
  */
  function getAuctionCount() external view returns (uint256) {
    return auctions.length;
  }

  /**
   * Return total number of auctions
   *
   * @return number of auctions
  */
  function getTotalBidCount() external view returns (uint256) {
    return bids.length;
  }

  /**
   * End an auction
   *
   * @param _auctionId auction id to end
  */
  function endAuction(uint _auctionId) external validId(_auctionId) validSeller(_auctionId) {
    _finalizeAuction(_auctionId);
  }

  /**
   * Claim an auction
   *
   * @param _auctionId auction id to end
  */
  function claimAuction(uint _auctionId) external validId(_auctionId) validWinner(_auctionId) {
    _finalizeAuction(_auctionId);
  }

  function _finalizeAuction(uint _auctionId) private {
    AuctionInfo storage auction = auctions[_auctionId];
    require(auction.end < block.timestamp, "Auction: Not ended yet");

    require(auction.status == AuctionStatus.Normal);
    auction.status = AuctionStatus.Ended;

    if(auction.bidder != address(0)) {
      (bool success, ) = auction.seller.call{ value: auction.price}("");
      require(success, 'Auction: unable to send value, recipient may have reverted');
      IERC721(auction.nft).safeTransferFrom(address(this), auction.bidder, auction.itemId);
    }

    wonCount[auction.bidder] = wonCount[auction.bidder].add(1);
    emit EndAuction(_msgSender(), _auctionId);
  }

  /**
   * Get bids of an auction
   *
   * @param _auctionId auction id
   *
   * @return bids
  */
  function getAuctionActivities(uint256 _auctionId) external view returns (uint256[] memory) {
    return bidsOfAuction[_auctionId];
  }
  
  /**
   * Get bids of user
   *
   * @param account address of user
   *
   * @return bids
  */
  function getUserBidding(address account) external view returns (uint256[] memory) {
    return bidsOfUser[account];
  }

  function onERC721Received(address, address, uint256, bytes calldata) external override pure returns (bytes4) {
    return _ERC721_RECEIVED;
  }
}

// File: /contracts/utils/OwnerPausable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "openzeppelin-solidity/contracts/access/Ownable.sol";
import "openzeppelin-solidity/contracts/security/Pausable.sol";

/**
 * @title OwnerPausable
 * @notice An ownable contract allows the owner to pause and unpause the
 * contract without a delay.
 * @dev Only methods using the provided modifiers will be paused.
 */
contract OwnerPausable is Ownable, Pausable {
  /**
   * @notice Pause the contract. Revert if already paused.
   */
  function pause() external onlyOwner {
    Pausable._pause();
  }

  /**
   * @notice Unpause the contract. Revert if already unpaused.
   */
  function unpause() external onlyOwner {
    Pausable._unpause();
  }
}

// File: openzeppelin-solidity/contracts/utils/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

// File: openzeppelin-solidity/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

// File: openzeppelin-solidity/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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 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.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: openzeppelin-solidity/contracts/token/ERC721/IERC721Receiver.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// File: openzeppelin-solidity/contracts/token/ERC721/IERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

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

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

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

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

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

// File: openzeppelin-solidity/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
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-solidity/contracts/security/Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// File: openzeppelin-solidity/contracts/interfaces/IERC721Receiver.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../token/ERC721/IERC721Receiver.sol";

// File: openzeppelin-solidity/contracts/interfaces/IERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../token/ERC721/IERC721.sol";

// File: openzeppelin-solidity/contracts/interfaces/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../token/ERC20/IERC20.sol";

// File: openzeppelin-solidity/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @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.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * 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.
 */
abstract 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() {
        _setOwner(_msgSender());
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the 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 virtual onlyOwner {
        _setOwner(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 virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}