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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), 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 {
        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 virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: @openzeppelin/contracts/cryptography/ECDSA.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        // Check the signature length
        if (signature.length != 65) {
            revert("ECDSA: invalid signature length");
        }

        // Divide the signature in r, s and v variables
        bytes32 r;
        bytes32 s;
        uint8 v;

        // ecrecover takes the signature parameters, and the only way to get them
        // currently is to use assembly.
        // solhint-disable-next-line no-inline-assembly
        assembly {
            r := mload(add(signature, 0x20))
            s := mload(add(signature, 0x40))
            v := byte(0, mload(add(signature, 0x60)))
        }

        return recover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover-bytes32-bytes-} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        require(uint256(s) <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0, "ECDSA: invalid signature 's' value");
        require(v == 27 || v == 28, "ECDSA: invalid signature 'v' value");

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        require(signer != address(0), "ECDSA: invalid signature");

        return signer;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * replicates the behavior of the
     * https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign[`eth_sign`]
     * JSON-RPC method.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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/contracts/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @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, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        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) {
        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) {
        // 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) {
        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) {
        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) {
        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) {
        require(b <= a, "SafeMath: subtraction overflow");
        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) {
        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, reverting 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) {
        require(b > 0, "SafeMath: division by zero");
        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) {
        require(b > 0, "SafeMath: modulo by zero");
        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) {
        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.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * 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) {
        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) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/proxy/Initializable.sol



// SPDX-License-Identifier: MIT

// solhint-disable-next-line compiler-version
pragma solidity >=0.4.24 <0.8.0;

import "../utils/Address.sol";

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 */
abstract contract Initializable {

    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(_initializing || _isConstructor() || !_initialized, "Initializable: contract is already initialized");

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }

    /// @dev Returns true if and only if the function is running in the constructor
    function _isConstructor() private view returns (bool) {
        return !Address.isContract(address(this));
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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/contracts/token/ERC20/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` 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));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    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. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "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: @openzeppelin/contracts/token/ERC721/ERC721Holder.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./IERC721Receiver.sol";

  /**
   * @dev Implementation of the {IERC721Receiver} interface.
   *
   * Accepts all token transfers. 
   * Make sure the contract is able to use its token with {IERC721-safeTransferFrom}, {IERC721-approve} or {IERC721-setApprovalForAll}.
   */
contract ERC721Holder is IERC721Receiver {

    /**
     * @dev See {IERC721Receiver-onERC721Received}.
     *
     * Always returns `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(address, address, uint256, bytes memory) public virtual override returns (bytes4) {
        return this.onERC721Received.selector;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

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

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

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

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

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

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

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

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

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

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

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

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

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

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

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

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

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

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

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

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

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

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

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

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

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

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 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.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual 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/utils/Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./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 () internal {
        _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/contracts/utils/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor () internal {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: contracts/EIP712Base.sol



pragma solidity ^0.6.8;

import "@openzeppelin/contracts/proxy/Initializable.sol";

contract EIP712Base is Initializable {
    struct EIP712Domain {
        string name;
        string version;
        address verifyingContract;
        uint256 chainId;
    }

    string constant public ERC712_VERSION = "1";

    bytes32 internal constant EIP712_DOMAIN_TYPEHASH = keccak256(
        bytes(
            "EIP712Domain(string name,string version,address verifyingContract,uint256 chainId)"
        )
    );
    bytes32 internal domainSeperator;

    // supposed to be called once while initializing.
    // one of the contractsa that inherits this contract follows proxy pattern
    // so it is not possible to do this in a constructor
    function _initializeEIP712(
        string memory name
    )
    internal
    initializer
    {
        _setDomainSeperator(name);
    }

    function _setDomainSeperator(string memory name) internal {
        domainSeperator = keccak256(
            abi.encode(
                EIP712_DOMAIN_TYPEHASH,
                keccak256(bytes(name)),
                keccak256(bytes(ERC712_VERSION)),
                address(this),
                getChainId()
            )
        );
    }

    function getDomainSeperator() public view returns (bytes32) {
        return domainSeperator;
    }

    function getChainId() public pure returns (uint256) {
        uint256 id;
        assembly {
            id := chainid()
        }
        return id;
    }

    /**
     * Accept message hash and returns hash message in EIP712 compatible form
     * So that it can be used to recover signer from signature signed using EIP712 formatted data
     * https://eips.ethereum.org/EIPS/eip-712
     * "\\x19" makes the encoding deterministic
     * "\\x01" is the version byte to make it compatible to EIP-191
     */
    function toTypedMessageHash(bytes32 messageHash)
    internal
    view
    returns (bytes32)
    {
        return
        keccak256(
            abi.encodePacked("\x19\x01", getDomainSeperator(), messageHash)
        );
    }
}
// File: contracts/FeeManager.sol



// SPDX-License-Identifier: Apache-2.0

pragma solidity ^0.6.8;

import "@openzeppelin/contracts/access/Ownable.sol";



contract FeeManager is Ownable {

    event ChangedFeePerMillion(uint256 cutPerMillion);
    event ChangedFeeForCollection(uint256 fee, address collection);
    event ChangedFeeReceiver(address _old, address _new);


    // Market fee on sales
//    uint256 public cutPerMillion;
    uint256 public constant maxCutPerMillion = 1e5; // 10% cut
    uint256 public constant PERCENTAGE = 1e6;
    uint256 public constant maxRoyalFee = 1e5;

    address public feeReceiver;

    mapping(address => uint256) public feeForCollection;

//    /**
//     * @dev Sets the share cut for the owner of the contract that's
//     *  charged to the seller on a successful sale
//     * @param _cutPerMillion - Share amount, from 0 to 99,999
//     */
//    function setOwnerCutPerMillion(uint256 _cutPerMillion) external onlyOwner {
//        require(
//            _cutPerMillion < maxCutPerMillion,
//            "The owner cut should be between 0 and maxCutPerMillion"
//        );
//
//        cutPerMillion = _cutPerMillion;
//        emit ChangedFeePerMillion(cutPerMillion);
//    }

    function setFeeForCollection(address _collection, uint256 _fee) external onlyOwner {
        require(
            _fee < maxCutPerMillion,
            "The owner cut should be between 0 and maxCutPerMillion"
        );
        feeForCollection[_collection] = _fee;
        emit ChangedFeeForCollection(_fee, _collection);

    }

    function setFeeReceiver(address _new) external onlyOwner {
        require(_new != address(0), "_new receiver is address zero");
        address _old =feeReceiver;
        feeReceiver = _new;
        emit ChangedFeeReceiver(_old, _new);
    }

}
// File: contracts/MarketplaceV2.sol



// SPDX-License-Identifier: Apache-2.0

pragma solidity ^0.6.8;

import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/utils/Pausable.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC721/ERC721Holder.sol";
import "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
import "@openzeppelin/contracts/cryptography/ECDSA.sol";

import "./FeeManager.sol";
import "./NativeMetaTransaction.sol";


interface IMarketplace {

    struct Order {
        // Order ID
        bytes32 id;
        // Owner of the NFT
        address payable seller;
        // NFT registry address
        address nftAddress;
        // Price (in wei) for the published item
        uint256 price;
        // Time when this sale ends
        uint256 expiresAt;
        // ERC20 currency address
        address currency;
        // Fixed price
        bool isAuction;
        // Creator
        address creator;
        // royal fee
        uint royalFee;
    }

    struct Bid {
        // Bid Id
        bytes32 id;
        // Bidder address
        address payable bidder;
        // Price for the bid in wei
        uint256 price;
        // Time when this bid ends
        uint256 expiresAt;
    }

    // ORDER EVENTS
    event OrderCreated(
        bytes32 id,
        address indexed seller,
        address indexed nftAddress,
        uint256 indexed assetId,
        uint256 priceInWei,
        uint256 expiresAt,
        address currency,
        bool isAuction
    );

    event OrderUpdated(
        bytes32 id,
        uint256 priceInWei,
        uint256 expiresAt
    );

    event OrderSuccessful(
        bytes32 id,
        address indexed buyer,
        uint256 priceInWei
    );

    event OrderCancelled(bytes32 id);

    // BID EVENTS
    event BidCreated(
        bytes32 id,
        address indexed nftAddress,
        uint256 indexed assetId,
        address indexed bidder,
        uint256 priceInWei,
        uint256 expiresAt
    );

    event BidAccepted(bytes32 id);
    event BidCancelled(bytes32 id);

    // INTERNAL EVENT
    event CreateOrderInternal(
        bytes32 id,
        address internalAddress
    );

    event BidCreatedInternal(
        bytes32 id,
        address indexed nftAddress,
        uint256 indexed assetId,
        address indexed bidder,
        uint256 priceInWei,
        uint256 expiresAt,
        address internalAddress
    );

    event LogInternal(
        bytes32 orderId,
        bytes32 bidId
    );

}

contract MarketplaceV2 is Pausable, FeeManager, IMarketplace, ERC721Holder, ReentrancyGuard {
    using ECDSA for bytes32;
    using ECDSA for bytes;
    using Address for address;
    using SafeMath for uint256;
    using SafeERC20 for IERC20;


    // From ERC721 registry assetId to Order (to avoid asset collision)
    mapping(address => mapping(uint256 => Order)) public orderByAssetId;

    // From ERC721 registry assetId to Bid (to avoid asset collision)
    mapping(address => mapping(uint256 => Bid)) public bidByOrderId;

    // From IERC20 to status for toggling accepted currencies
    mapping(address => bool) public acceptedCurrencies;

    // Allow NFT can be sold on this market
    mapping(address => bool) public whiteListNft;


    // 721 Interfaces
    bytes4 public constant _INTERFACE_ID_ERC721 = 0x80ac58cd;

    // Mocking a constant for ether as currency
    address public constant MARKETPLACE_ETHER = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;

    address public validator;

    address public internalLWC;

    modifier checkSigner(bytes memory _signature, address _creator, uint _royalFee) {
        require(_royalFee <= maxRoyalFee, "Marketplace: max royal fee");
        bytes32 _hash = keccak256(abi.encodePacked(_creator, msg.sender, address(this), _royalFee)).toEthSignedMessageHash();
        require(_hash.recover(_signature) == validator, "Marketplace: !verify");
        _;
    }

    modifier onlyInternalLWC() {
        require(msg.sender == internalLWC, "Only internal wallet");
        _;
    }

    event ChangeValidator(address indexed _old, address indexed _new);
    event ChangeInternalLWC(address indexed _old, address indexed _new);

    /**
     * @dev Initialize this contract. Acts as a constructor
     */
    constructor() public {
        acceptedCurrencies[MARKETPLACE_ETHER] = true;
        feeReceiver = msg.sender;
    }

    /**
     * @dev Sets the paused failsafe. Can only be called by owner
     * @param _setPaused - paused state
     */
    function setPaused(bool _setPaused) external onlyOwner {
        return (_setPaused) ? _pause() : _unpause();
    }

    /**
     * @dev Set accepted currencies as payments. Can only be called by owner
     * @param _token - ERC20 contract address
     * @param _status - status for the token
     */
    function setCurrency(address _token, bool _status) external onlyOwner {
        require(_token.isContract(), "The accepted token address must be a deployed contract");
        acceptedCurrencies[_token] = _status;
    }

    /**
     * @dev Set NFT can be sold on market. Can only be called by owner
     * @param _token - ERC721 contract address
     * @param _status - status for the token
     */
    function setNFT(address _token, bool _status) external onlyOwner {
        require(_token.isContract(), "The accepted token address must be a deployed contract");
        whiteListNft[_token] = _status;
    }


    function setValidator(address _validator) external onlyOwner {
        require(_validator != address(0) && !_validator.isContract(), "Marketplace: invalid address");
        address _old = validator;
        validator = _validator;
        emit ChangeValidator(_old, _validator);
    }

    function setInternalLWC(address _internalLWC) external onlyOwner {
        require(_internalLWC != address(0), "Marketplace: invalid address");
        address _old = internalLWC;
        internalLWC = _internalLWC;
        emit ChangeValidator(_old, _internalLWC);
    }

    /**
     * @dev Creates a new order
     * @param _nftAddress - Non fungible registry address
     * @param _assetId - ID of the published NFT
     * @param _priceInWei - Price in Wei for the supported coin
     * @param _expiresAt - Duration of the order (in hours)
     */
    function createOrder(address _nftAddress, uint256 _assetId, uint256 _priceInWei, uint256 _expiresAt, address _currency, bool _isAuction, address _creator, uint _royalFee, bytes memory _signature)
    external
    whenNotPaused
    checkSigner(_signature, _creator, _royalFee)
    {
        _createOrder(_nftAddress, _assetId, _priceInWei, _expiresAt, _currency, _isAuction, _creator, _royalFee);
    }

    function createOrderInternal(
        address _nftAddress,
        uint256 _assetId,
        uint256 _priceInWei,
        uint256 _expiresAt,
        address _currency,
        bool _isAuction,
        address _creator,
        uint _royalFee,
        bytes memory _signature,
        address _ownerInternal
    )
    external
    whenNotPaused
    checkSigner(_signature, _creator, _royalFee)
    onlyInternalLWC
    {
        bytes32 orderId = _createOrder(_nftAddress, _assetId, _priceInWei, _expiresAt, _currency, _isAuction, _creator, _royalFee);
        emit CreateOrderInternal(orderId, _ownerInternal);
    }
    /**
     * @dev Cancel an already published order
     *  can only be cancelled by seller or the contract owner
     * @param _nftAddress - Address of the NFT registry
     * @param _assetId - ID of the published NFT
     */
    function cancelOrder(address _nftAddress, uint256 _assetId) external {
        Order memory order = orderByAssetId[_nftAddress][_assetId];

        require(order.seller == msg.sender || msg.sender == owner(), "Marketplace: unauthorized sender");

        // Remove pending bid if any
        Bid memory bid = bidByOrderId[_nftAddress][_assetId];

        if (bid.id != 0) {
            _cancelBid(bid.id, _nftAddress, _assetId, bid.bidder, bid.price);
        }

        // Cancel order.
        _cancelOrder(order.id, _nftAddress, _assetId, order.seller);
    }

    /**
     * @dev Update an already published order
     *  can only be updated by seller
     * @param _nftAddress - Address of the NFT registry
     * @param _assetId - ID of the published NFT
     */
    function updateOrder(address _nftAddress, uint256 _assetId, uint256 _priceInWei, uint256 _expiresAt)
    external whenNotPaused {
        Order storage order = orderByAssetId[_nftAddress][_assetId];

        // Check valid order to update
        require(order.id != 0, "Marketplace: asset not published");
        require(order.seller == msg.sender, "Marketplace: sender not allowed");
        require(order.expiresAt >= block.timestamp, "Marketplace: order expired");

        // check order updated params
        require(_priceInWei > 0, "Marketplace: Price should be bigger than 0");
        require(_expiresAt > block.timestamp.add(1 minutes), "Marketplace: Expire time should be more than 1 minute in the future");

        order.price = _priceInWei;
        order.expiresAt = _expiresAt;

        emit OrderUpdated(order.id, _priceInWei, _expiresAt);
    }

    /**
     * @dev Executes the sale for a published NFT
     * @param _nftAddress - Address of the NFT registry
     * @param _assetId - ID of the published NFT
     */
    function safeExecuteOrder(address _nftAddress, uint256 _assetId, uint256 _priceInWei) external payable whenNotPaused {
        // Get the current valid order for the asset or fail
        Order memory order = _getValidOrder(_nftAddress, _assetId);

        /// Check the execution price matches the order price
        // require(order.price == msg.value, "Marketplace: invalid price");
        require(order.seller != msg.sender || msg.sender == internalLWC, "Marketplace: unauthorized sender");
        bool _isETH = order.currency == MARKETPLACE_ETHER;
        if(_isETH) {
            require(order.price == msg.value, "Marketplace: invalid price");
        } else {
            require(order.price == _priceInWei, "Marketplace: invalid price");
        }

        // market fee to cut
        uint256 saleShareAmount = 0;
        uint256 royalFeeShareAmount = 0;
        uint256 cutPerMillion = feeForCollection[order.nftAddress];
        uint256 sellerReceive = 0;

        if (cutPerMillion > 0) {
            // Calculate sale share
            if (_isETH) {
                saleShareAmount = (msg.value).mul(cutPerMillion).div(PERCENTAGE);
            } else {
                saleShareAmount = (order.price).mul(cutPerMillion).div(PERCENTAGE);
            }

            // Transfer share amount for marketplace Owner
//            order.currency == MARKETPLACE_ETHER ?
//            payable(owner()).transfer(saleShareAmount)
//            :
//            IERC20(order.currency).safeTransferFrom(msg.sender, owner(), saleShareAmount);
        }

        if (order.creator != address(0) && order.royalFee > 0 ) {
            // Calculate sale share
//            royalFeeShareAmount = (order.price).mul(order.royalFee).div(PERCENTAGE);
            if(_isETH) {
                royalFeeShareAmount = (msg.value).mul(order.royalFee).div(PERCENTAGE);
            } else {
                royalFeeShareAmount = (order.price).mul(order.royalFee).div(PERCENTAGE);
            }
//            order.currency == MARKETPLACE_ETHER ?
//            payable(order.creator).transfer(royalFeeShareAmount)
//            :
//            IERC20(order.currency).safeTransfer(order.creator, royalFeeShareAmount);
        }

        uint256 _totalFee = royalFeeShareAmount.add(saleShareAmount);
        if(order.price >= _totalFee) {
            sellerReceive = (order.price).sub(_totalFee);
        } else {
            revert("Fee is greater than price");
        }

        //payment
        if(_isETH) {
            payable(feeReceiver).transfer(saleShareAmount);
            payable(order.creator).transfer(royalFeeShareAmount);
            payable(order.seller).transfer(sellerReceive);
        } else {
            IERC20 _currency = IERC20(order.currency);
            _currency.safeTransferFrom(msg.sender, feeReceiver, saleShareAmount);
            _currency.safeTransferFrom(msg.sender, order.creator, royalFeeShareAmount);
            _currency.safeTransferFrom(msg.sender, order.seller, sellerReceive);
        }

//        // Transfer token amount minus market fee to seller
//        order.currency == MARKETPLACE_ETHER ?
//        order.seller.transfer(order.price.sub(saleShareAmount.add(royalFeeShareAmount)))
//        :
//        IERC20(order.currency).safeTransferFrom(msg.sender, order.seller, order.price.sub(saleShareAmount.add(royalFeeShareAmount)));

        // Remove pending bid if any
        Bid memory bid = bidByOrderId[_nftAddress][_assetId];
        if (bid.id != 0) {
            _cancelBid(bid.id, _nftAddress, _assetId, bid.bidder, bid.price);
        }
        _executeOrder(order.id, msg.sender, _nftAddress, _assetId, order.price);
    }

    /**
     * @dev Places a bid for a published NFT
     * @param _nftAddress - Address of the NFT registry
     * @param _assetId - ID of the published NFT
     * @param _expiresAt - Bid expiration time
     */
    function safePlaceBid(address _nftAddress, uint256 _assetId, uint256 _expiresAt, uint256 _priceInWei)
    external payable whenNotPaused nonReentrant {

        Order memory order = _getValidOrder(_nftAddress, _assetId);

        order.currency == MARKETPLACE_ETHER ?
        _createBid(_nftAddress, _assetId, msg.value, _expiresAt)
        :
        _createBid(_nftAddress, _assetId, _priceInWei, _expiresAt);
    }

    function safePlaceBidInternal(
        address _nftAddress,
        uint256 _assetId,
        uint256 _expiresAt,
        uint256 _priceInWei,
        address _internal)
    external payable whenNotPaused nonReentrant {

        Order memory order = _getValidOrder(_nftAddress, _assetId);

        bytes32 bidId = order.currency == MARKETPLACE_ETHER ?
        _createBid(_nftAddress, _assetId, msg.value, _expiresAt)
        :
        _createBid(_nftAddress, _assetId, _priceInWei, _expiresAt);

        emit BidCreatedInternal(bidId, _nftAddress, _assetId, msg.sender, _priceInWei, _expiresAt, _internal);

    }

    /**
     * @dev Cancel an already published bid
     *  can only be canceled by seller or the contract owner
     * @param _nftAddress - Address of the NFT registry
     * @param _assetId - ID of the published NFT
     */
    function cancelBid(address _nftAddress, uint256 _assetId) external whenNotPaused {
        Bid memory bid = bidByOrderId[_nftAddress][_assetId];

        require(bid.bidder == msg.sender, "Marketplace: Unauthorized sender");

        _cancelBid(bid.id, _nftAddress, _assetId, bid.bidder, bid.price);
    }

    /**
     * @dev Executes the sale for a published NFT by accepting a current bid
     * @param _nftAddress - Address of the NFT registry
     * @param _assetId - ID of the published NFT
     * @param _priceInWei - Bid price in wei in acceptedTokens currency
     */
    function acceptBid(address _nftAddress, uint256 _assetId, uint256 _priceInWei) external whenNotPaused {
        // check order validity
        Order memory order = _getValidOrder(_nftAddress, _assetId);

        // item seller is the only allowed to accept a bid
        require(order.seller == msg.sender, "Marketplace: unauthorized sender");

        Bid memory bid = bidByOrderId[_nftAddress][_assetId];

        require(bid.price == _priceInWei, "Marketplace: invalid bid price");
        require(bid.expiresAt >= block.timestamp, "Marketplace: the bid expired");

        // remove bid
        delete bidByOrderId[_nftAddress][_assetId];

        emit BidAccepted(bid.id);

        uint256 saleShareAmount = 0;
        uint256 royalFeeShareAmount = 0;
        uint256 cutPerMillion = feeForCollection[order.nftAddress];
        uint256 sellerReceive = 0;
        bool _isETH = order.currency == MARKETPLACE_ETHER;

        // Send market fees to owner
        if (cutPerMillion > 0) {
            // Calculate sale share
            saleShareAmount = (_priceInWei).mul(cutPerMillion).div(PERCENTAGE);

            // Transfer share amount for marketplace Owner
//            order.currency == MARKETPLACE_ETHER ?
//            payable(owner()).transfer(saleShareAmount)
//            :
//            IERC20(order.currency).safeTransfer(owner(), saleShareAmount);
        }

        if (order.creator != address(0) && order.royalFee > 0) {
            // Calculate sale share
            royalFeeShareAmount = (_priceInWei).mul(order.royalFee).div(PERCENTAGE);

//            order.currency == MARKETPLACE_ETHER ?
//            payable(order.creator).transfer(royalFeeShareAmount)
//            :
//            IERC20(order.currency).safeTransfer(order.creator, royalFeeShareAmount);
        }

        uint256 _totalFee = royalFeeShareAmount.add(saleShareAmount);
        if(_priceInWei >= _totalFee) {
            sellerReceive = (_priceInWei).sub(_totalFee);
        } else {
            revert("Fee is greater than price");
        }

        // Transfer token amount minus market fee to seller
//        order.currency == MARKETPLACE_ETHER ?
//        order.seller.transfer(bid.price.sub(saleShareAmount.add(royalFeeShareAmount)))
//        :
//        IERC20(order.currency).safeTransfer(order.seller, bid.price.sub(saleShareAmount.add(royalFeeShareAmount)));

        if(_isETH) {
            payable(feeReceiver).transfer(saleShareAmount);
            payable(order.creator).transfer(royalFeeShareAmount);
            payable(order.seller).transfer(sellerReceive);
        } else {
            IERC20 _currency = IERC20(order.currency);
            _currency.safeTransferFrom(msg.sender, feeReceiver, saleShareAmount);
            _currency.safeTransferFrom(msg.sender, order.creator, royalFeeShareAmount);
            _currency.safeTransferFrom(msg.sender, order.seller, sellerReceive);
        }

        _executeOrder(order.id, bid.bidder, _nftAddress, _assetId, _priceInWei);
        emit LogInternal(order.id, bid.id);
    }

    /**
     * @dev Internal function gets Order by nftRegistry and assetId. Checks for the order validity
     * @param _nftAddress - Address of the NFT registry
     * @param _assetId - ID of the published NFT
     */
    function _getValidOrder(address _nftAddress, uint256 _assetId) internal view returns (Order memory order) {
        order = orderByAssetId[_nftAddress][_assetId];

        require(order.id != 0, "Marketplace: asset not published");
        require(order.expiresAt >= block.timestamp, "Marketplace: order expired");
    }

    /**
     * @dev Executes the sale for a published NFT
     * @param _orderId - Order Id to execute
     * @param _buyer - address
     * @param _nftAddress - Address of the NFT registry
     * @param _assetId - NFT id
     * @param _priceInWei - Order price
     */
    function _executeOrder(bytes32 _orderId, address _buyer, address _nftAddress, uint256 _assetId, uint256 _priceInWei) internal {
        // remove order
        delete orderByAssetId[_nftAddress][_assetId];

        // Transfer NFT asset
        IERC721(_nftAddress).safeTransferFrom(address(this), _buyer, _assetId);

        // Notify ..
        emit OrderSuccessful(_orderId, _buyer, _priceInWei);
    }

    /**
     * @dev Creates a new order
     * @param _nftAddress - Non fungible registry address
     * @param _assetId - ID of the published NFT
     * @param _priceInWei - Price in Wei for the supported coin
     * @param _expiresAt - Expiration time for the order
     */
    function _createOrder(
        address _nftAddress,
        uint256 _assetId,
        uint256 _priceInWei,
        uint256 _expiresAt,
        address _currency,
        bool _isAuction,
        address _creator,
        uint256 _royalFee) internal returns(bytes32){
        // Check nft registry
        IERC721 nftRegistry = _requireERC721(_nftAddress);

        // Check _acceptedCurrency
        require(
            whiteListNft[_nftAddress],
            "Marketplace: Unacceptable marketplace nft"
        );

        // Check _acceptedCurrency
        require(
            acceptedCurrencies[_currency],
            "Marketplace: Unacceptable marketplace currency"
        );

        // Check order creator is the asset owner
        address assetOwner = nftRegistry.ownerOf(_assetId);

        require(
            assetOwner == msg.sender,
            "Marketplace: Only the asset owner can create orders"
        );

        require(_priceInWei > 0, "Marketplace: Price should be bigger than 0");

        require(
            _expiresAt > block.timestamp.add(1 minutes),
            "Marketplace: Publication should be more than 1 minute in the future"
        );

        // get NFT asset from seller
        nftRegistry.safeTransferFrom(assetOwner, address(this), _assetId);

        // create the orderId
        bytes32 orderId = keccak256(abi.encodePacked(block.timestamp, assetOwner, _nftAddress, _assetId, _priceInWei));

        // save order
        orderByAssetId[_nftAddress][_assetId] = Order({
        id : orderId,
        seller : payable(assetOwner),
        nftAddress : _nftAddress,
        price : _priceInWei,
        expiresAt : _expiresAt,
        currency : _currency,
        isAuction : _isAuction,
        creator : _creator,
        royalFee : _royalFee
        });

        emit OrderCreated(orderId, assetOwner, _nftAddress, _assetId, _priceInWei, _expiresAt, _currency, _isAuction);
        return orderId;
    }

    /**
     * @dev Creates a new bid on a existing order
     * @param _nftAddress - Non fungible registry address
     * @param _assetId - ID of the published NFT
     * @param _priceInWei - Price in Wei for the supported coin
     * @param _expiresAt - expires time
     */
    function _createBid(address _nftAddress, uint256 _assetId, uint256 _priceInWei, uint256 _expiresAt) internal  returns(bytes32){
        // Checks order validity
        Order memory order = _getValidOrder(_nftAddress, _assetId);
        require(order.isAuction, "Marketplace: only buy fixed price");
        // check on expire time
        if (_expiresAt > order.expiresAt) {
            _expiresAt = order.expiresAt;
        }

        // Check price if there's a previous bid
        Bid memory bid = bidByOrderId[_nftAddress][_assetId];

        // if theres no previous bid, just check price > 0
        if (bid.id != 0) {
            if (bid.expiresAt >= block.timestamp) {
                require(
                    _priceInWei > bid.price,
                    "Marketplace: bid price should be higher than last bid"
                );

            } else {
                require(_priceInWei > 0, "Marketplace: bid should be > 0");
            }

            _cancelBid(bid.id, _nftAddress, _assetId, bid.bidder, bid.price);

        } else {
            require(_priceInWei > 0, "Marketplace: bid should be > 0");
        }

        // Transfer sale amount from bidder to escrow
        // acceptedToken.safeTransferFrom(msg.sender, address(this), _priceInWei);

        // Create bid
        bytes32 bidId = keccak256(abi.encodePacked(block.timestamp, msg.sender, order.id, _priceInWei, _expiresAt));

        // Save Bid for this order
        bidByOrderId[_nftAddress][_assetId] = Bid({
        id : bidId,
        bidder : msg.sender,
        price : _priceInWei,
        expiresAt : _expiresAt
        });

        emit BidCreated(bidId, _nftAddress, _assetId, msg.sender, _priceInWei, _expiresAt);
        return bidId;
    }

    /**
     * @dev Cancel an already published order
     *  can only be canceled by seller or the contract owner
     * @param _orderId - Bid identifier
     * @param _nftAddress - Address of the NFT registry
     * @param _assetId - ID of the published NFT
     * @param _seller - Address
     */
    function _cancelOrder(bytes32 _orderId, address _nftAddress, uint256 _assetId, address _seller) internal {
        delete orderByAssetId[_nftAddress][_assetId];

        /// send asset back to seller
        IERC721(_nftAddress).safeTransferFrom(address(this), _seller, _assetId);

        emit OrderCancelled(_orderId);
    }

    /**
     * @dev Cancel bid from an already published order
     *  can only be canceled by seller or the contract owner
     * @param _bidId - Bid identifier
     * @param _nftAddress - registry address
     * @param _assetId - ID of the published NFT
     * @param _bidder - Address
     * @param _escrowAmount - in acceptenToken currency
     */
    function _cancelBid(bytes32 _bidId, address _nftAddress, uint256 _assetId, address payable _bidder, uint256 _escrowAmount) internal {
        delete bidByOrderId[_nftAddress][_assetId];

        Order memory order = _getValidOrder(_nftAddress, _assetId);

        order.currency == MARKETPLACE_ETHER ?
        _bidder.transfer(_escrowAmount)
        :
        IERC20(order.currency).safeTransfer(_bidder, _escrowAmount);

        emit BidCancelled(_bidId);
    }

    function _requireERC721(address _nftAddress) internal view returns (IERC721) {
        require(
            _nftAddress.isContract(),
            "The NFT Address should be a contract"
        );
        require(
            IERC721(_nftAddress).supportsInterface(_INTERFACE_ID_ERC721),
            "The NFT contract has an invalid ERC721 implementation"
        );
        return IERC721(_nftAddress);
    }

//    function _msgSender() internal virtual override(NativeMetaTransaction, Context) view returns (address payable) {
//        address payable sender;
//        if(msg.sender == address(this)) {
//            bytes memory array = msg.data;
//            uint256 index = msg.data.length;
//            assembly {
//            // Load the 32 bytes word from memory with the address on the lower 20 bytes, and mask those.
//                sender := and(mload(add(array, index)), 0xffffffffffffffffffffffffffffffffffffffff)
//            }
//        } else {
//            sender = msg.sender;
//        }
//        return sender;
//    }

    function resecureFund(IERC20 _erc20) external onlyOwner whenPaused {
        if(address(_erc20) == address(MARKETPLACE_ETHER)) {
            payable(owner()).transfer(address(this).balance);
        }else {
            _erc20.safeTransfer(owner(), _erc20.balanceOf(address(this)));
        }
    }
}
// File: contracts/NativeMetaTransaction.sol



pragma solidity ^0.6.8;

import "./EIP712Base.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";


contract NativeMetaTransaction is EIP712Base {
    using SafeMath for uint256;
    bytes32 private constant META_TRANSACTION_TYPEHASH = keccak256(
        bytes(
            "MetaTransaction(uint256 nonce,address from,bytes functionSignature)"
        )
    );
    event MetaTransactionExecuted(
        address userAddress,
        address payable relayerAddress,
        bytes functionSignature
    );
    mapping(address => uint256) nonces;

    /*
     * Meta transaction structure.
     * No point of including value field here as if user is doing value transfer then he has the funds to pay for gas
     * He should call the desired function directly in that case.
     */
    struct MetaTransaction {
        uint256 nonce;
        address from;
        bytes functionSignature;
    }

    function executeMetaTransaction(
        address userAddress,
        bytes memory functionSignature,
        bytes32 sigR,
        bytes32 sigS,
        uint8 sigV
    ) public payable returns (bytes memory) {
        MetaTransaction memory metaTx = MetaTransaction({
        nonce: nonces[userAddress],
        from: userAddress,
        functionSignature: functionSignature
        });

        require(
            verify(userAddress, metaTx, sigR, sigS, sigV),
            "Signer and signature do not match"
        );

        // increase nonce for user (to avoid re-use)
        nonces[userAddress] = nonces[userAddress].add(1);

        emit MetaTransactionExecuted(
            userAddress,
            msg.sender,
            functionSignature
        );

        // Append userAddress and relayer address at the end to extract it from calling context
        (bool success, bytes memory returnData) = address(this).call(
            abi.encodePacked(functionSignature, userAddress)
        );
        require(success, "Function call not successful");

        return returnData;
    }

    function hashMetaTransaction(MetaTransaction memory metaTx)
    internal
    pure
    returns (bytes32)
    {
        return
        keccak256(
            abi.encode(
                META_TRANSACTION_TYPEHASH,
                metaTx.nonce,
                metaTx.from,
                keccak256(metaTx.functionSignature)
            )
        );
    }

    function getNonce(address user) public view returns (uint256 nonce) {
        nonce = nonces[user];
    }

    function verify(
        address signer,
        MetaTransaction memory metaTx,
        bytes32 sigR,
        bytes32 sigS,
        uint8 sigV
    ) internal view returns (bool) {
        require(signer != address(0), "NativeMetaTransaction: INVALID_SIGNER");
        return
        signer ==
        ecrecover(
            toTypedMessageHash(hashMetaTransaction(metaTx)),
            sigV,
            sigR,
            sigS
        );
    }

    function _msgSender() internal virtual view returns (address payable) {
        address payable sender;
        if(msg.sender == address(this)) {
            bytes memory array = msg.data;
            uint256 index = msg.data.length;
            assembly {
            // Load the 32 bytes word from memory with the address on the lower 20 bytes, and mask those.
                sender := and(mload(add(array, index)), 0xffffffffffffffffffffffffffffffffffffffff)
            }
        } else {
            sender = msg.sender;
        }
        return sender;
    }

}