flurkV3.sol

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

// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

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/contracts/security/ReentrancyGuard.sol


// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

pragma solidity ^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() {
    _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 making 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: @openzeppelin/contracts/utils/introspection/IERC165.sol


// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

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/contracts/token/ERC721/IERC721.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

/**
 * @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: contracts/FlurksMarket.sol


pragma solidity 0.8.10;

/**
 * @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());
  }
}

/**
 * @dev Contract module which provides access control
 *
 * the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * mapped to 
 * `onlyOwner`
 */
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);
  }
}

contract FlurksMarket is Context, ReentrancyGuard, Pausable, Ownable {
  IERC721 flurksContract; // instance of the Flurks contract

  struct Offer {
    bool isForSale;
    uint flurkID;
    address seller;
    uint minValue; // in ether
    address onlySellTo;
  }

  struct Bid {
    bool hasBid;
    uint flurkID;
    address bidder;
    uint value;
  }

  // A record of flurks that are offered for sale at a specific minimum value, and perhaps to a specific person
  mapping (uint => Offer) public flurkOffers;

  // A record of the highest flurk bid
  mapping (uint => Bid) public flurkBids;

  // A record of pending ETH withdrawls by address
  mapping (address => uint) public pendingWithdrawals;

  event FlurkOfferCreated(uint indexed flurkID, uint minValue, address indexed Oferrer);
  event FlurkOfferWithdrawn(uint indexed flurkID);

  event FlurkBidCreated(uint indexed flurkID, uint value, address indexed fromAddress);
  event FlurkBidWithdrawn(uint indexed flurkID, uint value, address indexed fromAddress);

  event FlurkBought(uint indexed flurkID, uint value, address indexed fromAddress, address indexed toAddress);

  // Initializes contract with an instance of Flurks contract, and sets deployer as owner
  constructor(address initialFlurksAddress) {
    flurksContract = IERC721(initialFlurksAddress);
  }

  function pause() public whenNotPaused onlyOwner {
    _pause();
  }

  function unpause() public whenPaused onlyOwner {
    _unpause();
  }

  modifier onlyHeckingCuteAndValidFlurk(uint flurkID) {
    require(flurkID <= 4984, "flurk ID is not cute and valid");
    _;
  }

  modifier onlyFlurkOwner(uint flurkID) {
    require(flurksContract.ownerOf(flurkID) == _msgSender(), "you are not the owner of this token");
    _;
  }

  // Allows the owner of a Flurks to stop offering it for sale
  function WithdrawFlurk(uint flurkID) public
    nonReentrant
    onlyHeckingCuteAndValidFlurk(flurkID)
    onlyFlurkOwner(flurkID)
  {
    flurkOffers[flurkID] = Offer(false, flurkID, _msgSender(), 0, address(0x0));
    emit FlurkOfferWithdrawn(flurkID);
  }

  // Allows a CryptoFlurk owner to offer it for sale
  function OfferFlurk(uint flurkID, uint minSalePriceInWei) public
    whenNotPaused
    nonReentrant
    onlyHeckingCuteAndValidFlurk(flurkID)
    onlyFlurkOwner(flurkID)
  {
    flurkOffers[flurkID] = Offer(true, flurkID, _msgSender(), minSalePriceInWei, address(0x0));
    emit FlurkOfferCreated(flurkID, minSalePriceInWei, address(0x0));
  }

  // Allows a CryptoFlurk owner to offer it for sale to a specific address
  function OfferFlurkToAddress(uint flurkID, uint minSalePriceInWei, address toAddress) public
    whenNotPaused
    nonReentrant
    onlyHeckingCuteAndValidFlurk(flurkID)
    onlyFlurkOwner(flurkID)
  {
    flurkOffers[flurkID] = Offer(true, flurkID, _msgSender(), minSalePriceInWei, toAddress);
    emit FlurkOfferCreated(flurkID, minSalePriceInWei, toAddress);
  }

  // Allows users to buy a Flurk offered for sale
  function BuyFlurk(uint flurkID) payable public
    whenNotPaused
    nonReentrant 
    onlyHeckingCuteAndValidFlurk(flurkID) 
  {
    Offer memory offer = flurkOffers[flurkID];
    require(offer.isForSale, "flurk is not for sale!");
    // Check if offer is valid for anyone or a specific address
    require(offer.onlySellTo == address(0x0) || offer.onlySellTo == _msgSender(), "this offer is not for you");
    require(msg.value == offer.minValue, "not enough ether"); // Didn"t send enough ETH

    address seller = offer.seller;
    require(seller != _msgSender(), "seller cannot buy its own token");
    require(seller == flurksContract.ownerOf(flurkID), "seller no longer owner of flurk");

    flurkOffers[flurkID] = Offer(false, flurkID, _msgSender(), 0, address(0x0));
    flurksContract.safeTransferFrom(seller, _msgSender(), flurkID);
    pendingWithdrawals[seller] += msg.value;
    emit FlurkBought(flurkID, msg.value, seller, _msgSender());

    // Check for the case where there is a bid from the new owner and refund it.
    // Any other bid can stay in place.
    Bid memory bid = flurkBids[flurkID];
    if (bid.bidder == _msgSender()) {
      // Kill bid and refund value
      pendingWithdrawals[_msgSender()] += bid.value;
      flurkBids[flurkID] = Bid(false, flurkID, address(0x0), 0);
    }
  }

  // Allows users to enter bids for any Flurk
  function BidFlurk(uint flurkID) payable public
    whenNotPaused
    nonReentrant
    onlyHeckingCuteAndValidFlurk(flurkID)
  {
    require(flurksContract.ownerOf(flurkID) != _msgSender(), "you already own this flurk");
    require(msg.value > 0, "cannot enter bid of zero");
    
    Bid memory existing = flurkBids[flurkID];
    require(msg.value > existing.value, "your bid is too low");
    
    if (existing.value > 0) { // Refund the failing bid
      pendingWithdrawals[existing.bidder] += existing.value;
    }

    flurkBids[flurkID] = Bid(true, flurkID, _msgSender(), msg.value);
    emit FlurkBidCreated(flurkID, msg.value, _msgSender());
  }

  // Allows Flurk owners to accept bids for their Flurks
  function AcceptFlurkBid(uint flurkID, uint minPrice) public
    whenNotPaused
    nonReentrant
    onlyHeckingCuteAndValidFlurk(flurkID)
    onlyFlurkOwner(flurkID) 
  {
    address seller = _msgSender();
    Bid memory bid = flurkBids[flurkID];

    require(bid.value > 0, "cannot enter bid of zero");
    require(bid.value > minPrice, "your bid is too low");
    require(seller != bid.bidder, "you already own this token");

    // remove flurk offer
    flurkOffers[flurkID] = Offer(false, flurkID, bid.bidder, 0, address(0x0));

    // remove flurk bid
    flurkBids[flurkID] = Bid(false, flurkID, address(0x0), 0);
    
    // send the token to the bidder
    flurksContract.safeTransferFrom(_msgSender(), bid.bidder, flurkID);
    
    // pay the seller
    pendingWithdrawals[seller] += bid.value;
    emit FlurkBought(flurkID, bid.value, seller, bid.bidder);
  }

  // Allows bidders to withdraw their bids 
  function WithdrawFlurkBid(uint flurkID) public 
    nonReentrant
    onlyHeckingCuteAndValidFlurk(flurkID)
  {
    Bid memory bid = flurkBids[flurkID];
    require(bid.bidder == _msgSender(), "the bidder is not message sender");

    emit FlurkBidWithdrawn(flurkID, bid.value, _msgSender());
    uint amount = bid.value;
    flurkBids[flurkID] = Bid(false, flurkID, address(0x0), 0);

    // Refund the bid money
    payable(_msgSender()).transfer(amount);
  }

  // Allows users to retrieve ETH from sales
  function withdraw() public nonReentrant {
    uint amount = pendingWithdrawals[_msgSender()];
    // Remember to zero the pending refund before
    // sending to prevent re-entrancy attacks
    pendingWithdrawals[_msgSender()] = 0;
    payable(_msgSender()).transfer(amount);
  }
}