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Contract Diff Checker

Contract Name:
KrownMarketplace

Contract Source Code:

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)

pragma solidity ^0.8.20;

import {Context} from "../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.
 *
 * The initial owner is set to the address provided by the deployer. 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;

    /**
     * @dev The caller account is not authorized to perform an operation.
     */
    error OwnableUnauthorizedAccount(address account);

    /**
     * @dev The owner is not a valid owner account. (eg. `address(0)`)
     */
    error OwnableInvalidOwner(address owner);

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

    /**
     * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
     */
    constructor(address initialOwner) {
        if (initialOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(initialOwner);
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        if (owner() != _msgSender()) {
            revert OwnableUnauthorizedAccount(_msgSender());
        }
    }

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

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.20;

import {IERC165} from "../../utils/introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC-721 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`.
     *
     * 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;

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC-721 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 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: Note that the caller is responsible to confirm that the recipient is capable of receiving ERC-721
     * or else they may be permanently lost. Usage of {safeTransferFrom} prevents loss, though the caller must
     * understand this adds an external call which potentially creates a reentrancy vulnerability.
     *
     * 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 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 address zero.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool approved) external;

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

    /**
     * @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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.20;

/**
 * @title ERC-721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC-721 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 `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.1) (utils/Context.sol)

pragma solidity ^0.8.20;

/**
 * @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;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (utils/introspection/IERC165.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC-165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[ERC].
 *
 * 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[ERC 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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/Pausable.sol)

pragma solidity ^0.8.20;

import {Context} from "../utils/Context.sol";

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

    /**
     * @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);

    /**
     * @dev The operation failed because the contract is paused.
     */
    error EnforcedPause();

    /**
     * @dev The operation failed because the contract is not paused.
     */
    error ExpectedPause();

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

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

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

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

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        if (paused()) {
            revert EnforcedPause();
        }
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        if (!paused()) {
            revert ExpectedPause();
        }
    }

    /**
     * @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());
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (utils/ReentrancyGuard.sol)

pragma solidity ^0.8.20;

/**
 * @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 EIP-1153 (transient storage) is available on the chain you're deploying at,
 * consider using {ReentrancyGuardTransient} instead.
 *
 * 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;

    /**
     * @dev Unauthorized reentrant call.
     */
    error ReentrancyGuardReentrantCall();

    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() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be NOT_ENTERED
        if (_status == ENTERED) {
            revert ReentrancyGuardReentrantCall();
        }

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

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

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == ENTERED;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

interface IEIP2981 {
    /**
     * @dev Returns how much royalty is owed and to whom, based on a sale price that may be denominated in any unit of
     * exchange. The royalty amount is denominated and should be paid in that same unit of exchange.
     * @param tokenId The NFT token ID being sold
     * @param salePrice The price of the NFT asset specified
     * @return receiver Address of who should be sent the royalty payment
     * @return royaltyAmount The royalty payment amount for salePrice
     */
    function royaltyInfo(uint256 tokenId, uint256 salePrice)
        external
        view
        returns (address receiver, uint256 royaltyAmount);
}

// SPDX-License-Identifier: MIT

/*
 /$$   /$$ /$$$$$$$   /$$$$$$  /$$      /$$ /$$   /$$       /$$        /$$$$$$  /$$$$$$$   /$$$$$$$ 
| $$  /$$/| $$__  $$ /$$__  $$| $$  /$ | $$| $$$ | $$      | $$       /$$__  $$| $$__  $$ /$$__  $$
| $$ /$$/ | $$  \ $$| $$  \ $$| $$ /$$$| $$| $$$$| $$      | $$      | $$  \ $$| $$  \ $$| $$  \__/
| $$$$$/  | $$$$$$$/| $$  | $$| $$/$$ $$ $$| $$ $$ $$      | $$      | $$$$$$$$| $$$$$$$ |  $$$$$$ 
| $$  $$  | $$__  $$| $$  | $$| $$$$_  $$$$| $$  $$$$      | $$      | $$__  $$| $$__  $$ \____  $$
| $$\  $$ | $$  \ $$| $$  | $$| $$$/ \  $$$| $$\  $$$      | $$      | $$  | $$| $$  \ $$ /$$  \ $$
| $$ \  $$| $$  | $$|  $$$$$$/| $$/   \  $$| $$ \  $$      | $$$$$$$$| $$  | $$| $$$$$$$/|  $$$$$$/
|__/  \__/|__/  |__/ \______/ |__/     \__/|__/  \__/      |________/|__/  |__/|_______/  \______/ 

krownlabs.app
x.com/krownlabs
discord.gg/KTU4krfhrG

*/

pragma solidity ^0.8.20;

import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Pausable.sol";
import "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import "@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol";
import "@openzeppelin/contracts/utils/introspection/IERC165.sol";
import "./IEIP2981.sol";

interface IERC721WithOwner is IERC721 {
    function owner() external view returns (address);
}

contract KrownMarketplace is 
    Ownable,
    ReentrancyGuard,
    Pausable,
    IERC721Receiver 
{
    /* ========== CONSTANTS ========== */

    uint256 public constant MAX_ROYALTY = 1000; // 10%
    uint256 public constant MIN_ROYALTY = 50; // 0,5%
    uint256 public constant MAX_PRICE = 1000000 ether; // 1m ether
    uint256 public constant MIN_PRICE = 0.001 ether;
    uint256 public constant BID_TIMEOUT = 24 hours;
    uint256 public constant MIN_EXPIRATION_TIME = 1 hours;
    uint256 public constant MAX_EXPIRATION_TIME = 90 days;
    uint256 public constant CLEANUP_BATCH_SIZE = 50;
    uint256 public constant PRICE_UPDATE_DELAY = 5 minutes;
    uint256 public constant MIN_BID_INCREMENT = 5; // 5%

    /* ========== STRUCTS ========== */

    struct Listing {
        address seller;
        address nftContract;
        uint256 tokenId;
        uint96 price;
        bool active;
        uint96 highestBid;
        address highestBidder;
        bool acceptingBids;
        uint40 listingTime;
        uint40 expirationTime;
        uint40 lastPriceUpdate;
    }

    struct CollectionListings {
        Listing[] listings;
        mapping(uint256 => uint256) tokenIdToIndex;
        mapping(uint256 => bool) isListed;
        uint256 activeListingsCount;
    }

    struct Bid {
        address bidder;
        uint96 amount;
        uint40 timestamp;
    }

    struct RoyaltyInfo {
        address receiver;
        uint96 percentage;
    }

    /* ========== STATE VARIABLES ========== */

    uint256 public marketplaceFee;
    mapping(address => CollectionListings) public collectionListings;
    mapping(address => mapping(uint256 => Bid[])) public bidsHistory;
    mapping(address => uint256) private pendingPayments;
    mapping(address => RoyaltyInfo) public collectionRoyalties;
    mapping(address => bool) public collectionOwners;

    /* ========== EVENTS ========== */

    event Listed(
        address indexed seller,
        address indexed nftContract,
        uint256 indexed tokenId,
        uint256 price,
        bool acceptingBids,
        uint256 expirationTime
    );
    event Sale(
        address indexed seller,
        address indexed buyer,
        address indexed nftContract,
        uint256 tokenId,
        uint256 price
    );
    event Cancelled(
        address indexed seller,
        address indexed nftContract,
        uint256 indexed tokenId
    );
    event BidPlaced(
        address indexed bidder,
        address indexed nftContract,
        uint256 indexed tokenId,
        uint256 amount
    );
    event BidAccepted(
        address indexed seller,
        address indexed bidder,
        address indexed nftContract,
        uint256 tokenId,
        uint256 amount
    );
    event PaymentPending(
        address indexed recipient,
        uint256 amount
    );
    event MarketplaceFeeUpdated(uint256 newFee);
    event EmergencyWithdraw(address indexed recipient, uint256 amount);
    event CollectionListingsCleaned(address indexed nftContract, uint256 count);
    event RoyaltySet(
        address indexed nftContract, 
        address indexed receiver, 
        uint256 percentage
    );

    /* ========== ERRORS ========== */

    error ZeroAddress();
    error UnauthorizedCaller();
    error InvalidPrice();
    error ListingNotActive();
    error InvalidExpiration();
    error BidTooLow();
    error ListingExpired();
    error InvalidInterface();
    error NotListed();
    error TransferFailed();
    error RoyaltyTooHigh();
    error BidNotAllowed();
    error NoValidBid();
    error BatchSizeTooLarge();
    error PriceUpdateTooSoon();
    error InsufficientPendingPayment();
    error PriceExceedsMaximum();
    error RoyaltyTooLow();

    /* ========== MODIFIERS ========== */

    modifier checkPrice(uint256 price) {
        if (price < MIN_PRICE || price > MAX_PRICE) revert InvalidPrice();
        _;
    }

    modifier onlyCollectionOwner(address nftContract) {
        if (!collectionOwners[nftContract] || 
            msg.sender != IERC721WithOwner(nftContract).owner()) {
            revert UnauthorizedCaller();
        }
        _;
    }

    /* ========== CONSTRUCTOR ========== */

    constructor(
        uint256 _marketplaceFee
    ) Ownable(msg.sender) {
        if(_marketplaceFee > 1000) revert InvalidPrice();
        marketplaceFee = _marketplaceFee;
    }


    /* ========== MAIN FUNCTIONS ========== */

    function listNFT(
        address _nftContract,
        uint256 _tokenId,
        uint256 _price,
        bool _acceptingBids,
        uint256 _expirationTime
    ) external 
        whenNotPaused 
        nonReentrant
        checkPrice(_price)
    {
        if(collectionListings[_nftContract].isListed[_tokenId]) revert NotListed();
        if(_expirationTime < block.timestamp + MIN_EXPIRATION_TIME ||
           _expirationTime > block.timestamp + MAX_EXPIRATION_TIME) {
            revert InvalidExpiration();
        }

        // Interface and ownership checks
        IERC721 nft = IERC721(_nftContract);
        if(!_checkInterface(nft)) revert InvalidInterface();
        if(nft.ownerOf(_tokenId) != msg.sender) revert UnauthorizedCaller();
        if(nft.getApproved(_tokenId) != address(this) && 
           !nft.isApprovedForAll(msg.sender, address(this))) {
            revert UnauthorizedCaller();
        }

        Listing memory listing = Listing({
            seller: msg.sender,
            nftContract: _nftContract,
            tokenId: _tokenId,
            price: uint96(_price),
            active: true,
            highestBid: 0,
            highestBidder: address(0),
            acceptingBids: _acceptingBids,
            listingTime: uint40(block.timestamp),
            expirationTime: uint40(_expirationTime),
            lastPriceUpdate: uint40(block.timestamp)
        });

        CollectionListings storage collection = collectionListings[_nftContract];
        collection.listings.push(listing);
        collection.tokenIdToIndex[_tokenId] = collection.listings.length - 1;
        collection.isListed[_tokenId] = true;
        collection.activeListingsCount++;

        emit Listed(msg.sender, _nftContract, _tokenId, _price, _acceptingBids, _expirationTime);
    }

    function buyNFT(
        address _nftContract,
        uint256 _tokenId,
        uint256 maxPrice
    ) external payable nonReentrant whenNotPaused {
        CollectionListings storage collection = collectionListings[_nftContract];
        if(!collection.isListed[_tokenId]) revert NotListed();
        
        Listing storage listing = collection.listings[collection.tokenIdToIndex[_tokenId]];
        
        if(!listing.active) revert ListingNotActive();
        if(msg.value != listing.price) revert InvalidPrice();
        if(listing.price > maxPrice) revert PriceExceedsMaximum();
        if(listing.seller == msg.sender) revert UnauthorizedCaller();
        if(block.timestamp >= listing.expirationTime) revert ListingExpired();
        
        // Verify current ownership
        if(IERC721(_nftContract).ownerOf(_tokenId) != listing.seller) {
            revert UnauthorizedCaller();
        }

        address seller = listing.seller;
        uint256 price = listing.price;
        
        // Remove listing first
        _removeListingFromCollection(_nftContract, _tokenId);
        
        // Handle payments through pending payments
        _distributePendingPayments(price, seller, _nftContract);
        
        // Transfer NFT last
        IERC721(_nftContract).safeTransferFrom(seller, msg.sender, _tokenId);

        emit Sale(seller, msg.sender, _nftContract, _tokenId, price);
    }

    function placeBid(
        address _nftContract,
        uint256 _tokenId
    ) external payable nonReentrant whenNotPaused {
        CollectionListings storage collection = collectionListings[_nftContract];
        if(!collection.isListed[_tokenId]) revert NotListed();
        
        Listing storage listing = collection.listings[collection.tokenIdToIndex[_tokenId]];
        
        if(!listing.active) revert ListingNotActive();
        if(!listing.acceptingBids) revert BidNotAllowed();
        if(msg.sender == listing.seller) revert UnauthorizedCaller();
        
        // Minimum bid increment check
        uint256 minBidRequired = listing.highestBid + (listing.highestBid * MIN_BID_INCREMENT / 100);
        if(msg.value <= minBidRequired) revert BidTooLow();
        if(msg.value < listing.price) revert BidTooLow();
        if(block.timestamp >= listing.expirationTime) revert ListingExpired();
        
        // Verify current ownership
        if(IERC721(listing.nftContract).ownerOf(listing.tokenId) != listing.seller) {
            revert UnauthorizedCaller();
        }

        // Return funds to previous highest bidder through pending payments
        if(listing.highestBidder != address(0)) {
            pendingPayments[listing.highestBidder] += listing.highestBid;
            emit PaymentPending(listing.highestBidder, listing.highestBid);
        }

        // Update bid information
        listing.highestBid = uint96(msg.value);
        listing.highestBidder = msg.sender;

        // Record bid in history
        bidsHistory[_nftContract][_tokenId].push(Bid({
            bidder: msg.sender,
            amount: uint96(msg.value),
            timestamp: uint40(block.timestamp)
        }));

        emit BidPlaced(msg.sender, _nftContract, _tokenId, msg.value);
    }

    function acceptBid(
        address _nftContract,
        uint256 _tokenId
    ) external nonReentrant whenNotPaused {
        CollectionListings storage collection = collectionListings[_nftContract];
        if(!collection.isListed[_tokenId]) revert NotListed();
        
        Listing storage listing = collection.listings[collection.tokenIdToIndex[_tokenId]];
        
        if(msg.sender != listing.seller) revert UnauthorizedCaller();
        if(!listing.active || !listing.acceptingBids) revert ListingNotActive();
        if(listing.highestBidder == address(0)) revert NoValidBid();
        if(block.timestamp >= listing.expirationTime) revert ListingExpired();
        
        // Verify current ownership
        if(IERC721(_nftContract).ownerOf(_tokenId) != msg.sender) {
            revert UnauthorizedCaller();
        }

        address buyer = listing.highestBidder;
        uint256 salePrice = listing.highestBid;
        
        // Remove listing
        _removeListingFromCollection(_nftContract, _tokenId);
        
        // Handle payments
        _distributePendingPayments(salePrice, msg.sender, _nftContract);
        
        // Transfer NFT
        IERC721(_nftContract).safeTransferFrom(msg.sender, buyer, _tokenId);

        emit BidAccepted(msg.sender, buyer, _nftContract, _tokenId, salePrice);
    }

    function cancelListing(
        address _nftContract,
        uint256 _tokenId
    ) external whenNotPaused {
        CollectionListings storage collection = collectionListings[_nftContract];
        if(!collection.isListed[_tokenId]) revert NotListed();
        
        Listing storage listing = collection.listings[collection.tokenIdToIndex[_tokenId]];
        
        if(listing.seller != msg.sender && owner() != msg.sender) {
            revert UnauthorizedCaller();
        }
        if(!listing.active) revert ListingNotActive();

        if(listing.highestBidder != address(0)) {
            pendingPayments[listing.highestBidder] += listing.highestBid;
            emit PaymentPending(listing.highestBidder, listing.highestBid);
        }

        _removeListingFromCollection(_nftContract, _tokenId);
        emit Cancelled(msg.sender, _nftContract, _tokenId);
    }

    /* ========== COLLECTION MANAGEMENT ========== */

    function registerAsCollectionOwner(address nftContract) external {
        if(nftContract == address(0)) revert ZeroAddress();
        if(!_checkInterface(IERC721(nftContract))) revert InvalidInterface();
        if(msg.sender != IERC721WithOwner(nftContract).owner()) {
            revert UnauthorizedCaller();
        }
        collectionOwners[nftContract] = true;
    }

    function setRoyalty(
        address nftContract,
        address receiver,
        uint256 percentage
    ) external onlyCollectionOwner(nftContract) {
        if(percentage > MAX_ROYALTY) revert RoyaltyTooHigh();
        if(percentage < MIN_ROYALTY) revert RoyaltyTooLow();
        if(receiver == address(0)) revert ZeroAddress();

        collectionRoyalties[nftContract] = RoyaltyInfo({
            receiver: receiver,
            percentage: uint96(percentage)
        });
        
        emit RoyaltySet(nftContract, receiver, percentage);
    }

    /* ========== INTERNAL FUNCTIONS ========== */

    function _removeListingFromCollection(address nftContract, uint256 tokenId) internal {
        CollectionListings storage collection = collectionListings[nftContract];
        uint256 index = collection.tokenIdToIndex[tokenId];
        uint256 lastIndex = collection.listings.length - 1;
        
        if (index != lastIndex) {
            Listing memory lastListing = collection.listings[lastIndex];
            collection.listings[index] = lastListing;
            collection.tokenIdToIndex[lastListing.tokenId] = index;
        }
        
        collection.listings.pop();
        delete collection.tokenIdToIndex[tokenId];
        delete collection.isListed[tokenId];
        
        if (collection.activeListingsCount > 0) {
            collection.activeListingsCount--;
        }
    }

    function _distributePendingPayments(
        uint256 amount,
        address seller,
        address nftContract
    ) internal {
        uint256 marketplaceFeeAmount = (amount * marketplaceFee) / 10000;
        uint256 remainingAmount = amount - marketplaceFeeAmount;

        // Handle royalties
        (address royaltyReceiver, uint256 royaltyAmount) = _getRoyalty(nftContract, amount);
        if (royaltyReceiver != address(0)) {
            remainingAmount -= royaltyAmount;
            // Direct transfer of royalties
            (bool royaltySent,) = payable(royaltyReceiver).call{value: royaltyAmount}("");
            if(!royaltySent) revert TransferFailed();
            emit PaymentPending(royaltyReceiver, 0);
        }

        // Direct transfer of marketplace fee
        (bool feeSent,) = payable(owner()).call{value: marketplaceFeeAmount}("");
        if(!feeSent) revert TransferFailed();
        emit PaymentPending(address(this), 0);

        // Direct transfer to seller
        (bool sellerSent,) = payable(seller).call{value: remainingAmount}("");
        if(!sellerSent) revert TransferFailed();
        emit PaymentPending(seller, 0);
    }

    function _getRoyalty(
        address nftContract,
        uint256 amount
    ) internal view returns (address receiver, uint256 royaltyAmount) {
        // First check if there's a manually set royalty
        RoyaltyInfo memory royalty = collectionRoyalties[nftContract];
        if (royalty.receiver != address(0)) {
            return (royalty.receiver, (amount * royalty.percentage) / 10000);
        }

        // If no manual royalty, check if contract supports EIP2981 interface
        try IERC165(nftContract).supportsInterface(0x2a55205a) returns (bool supported) {
            // Only try to get royalty info if interface is supported
            if (supported) {
                try IEIP2981(nftContract).royaltyInfo(0, amount) returns (
                    address _receiver,
                    uint256 _royaltyAmount
                ) {
                    if (_receiver != address(0)) {
                        // Limit royalty to 10%
                        uint256 maxRoyalty = (amount * MAX_ROYALTY) / 10000;
                        return (_receiver, _royaltyAmount > maxRoyalty ? maxRoyalty : _royaltyAmount);
                    }
                } catch {
                    return (address(0), 0);
                }
            }
        } catch {
            return (address(0), 0);
        }

        return (address(0), 0);
    }

    function _checkInterface(IERC721 nft) internal view returns (bool) {
        try nft.supportsInterface(type(IERC721).interfaceId) returns (bool supported) {
            return supported;
        } catch {
            return false;
        }
    }

    /* ========== PAYMENT FUNCTIONS ========== */

    function withdrawPendingPayments() external nonReentrant whenNotPaused {
        uint256 amount = pendingPayments[msg.sender];
        if(amount == 0) revert InsufficientPendingPayment();

        // Update state before transfer
        pendingPayments[msg.sender] = 0;
        
        // Execute transfer
        (bool sent,) = payable(msg.sender).call{value: amount}("");
        if(!sent) revert TransferFailed();
        
        emit PaymentPending(msg.sender, 0); // Update pending amount to 0
    }

    /* ========== ADMIN FUNCTIONS ========== */

    function updateMarketplaceFee(uint256 _newFee) external onlyOwner {
        if(_newFee > 1000) revert InvalidPrice();
        marketplaceFee = _newFee;
        emit MarketplaceFeeUpdated(_newFee);
    }

    function emergencyWithdraw() external onlyOwner {
        uint256 balance = address(this).balance;
        if(balance > 0) {
            (bool success,) = payable(owner()).call{value: balance}("");
            if(!success) revert TransferFailed();
            emit EmergencyWithdraw(owner(), balance);
        }
    }

    function pause() external onlyOwner {
        _pause();
    }

    function unpause() external onlyOwner {
        _unpause();
    }

    /* ========== MAINTENANCE FUNCTIONS ========== */

    function cleanupExpiredListings(
        address nftContract,
        uint256 batchSize
    ) external nonReentrant {
        if(batchSize > CLEANUP_BATCH_SIZE) revert BatchSizeTooLarge();
        
        CollectionListings storage collection = collectionListings[nftContract];
        uint256 length = collection.listings.length;
        uint256 processed = 0;
        uint256 cleanedCount = 0;
        
        for (uint256 i = 0; i < length && processed < batchSize; i++) {
            Listing memory listing = collection.listings[i];
            
            if (listing.active && block.timestamp >= listing.expirationTime) {
                if (listing.highestBidder != address(0)) {
                    pendingPayments[listing.highestBidder] += listing.highestBid;
                    emit PaymentPending(listing.highestBidder, listing.highestBid);
                }
                
                _removeListingFromCollection(nftContract, listing.tokenId);
                cleanedCount++;
            }
            
            processed++;
        }
        
        if (cleanedCount > 0) {
            emit CollectionListingsCleaned(nftContract, cleanedCount);
        }
    }

    /* ========== VIEW FUNCTIONS ========== */

    function getPendingPayment(address user) external view returns (uint256) {
        return pendingPayments[user];
    }

    function getCollectionListings(
        address nftContract,
        uint256 offset,
        uint256 limit
    ) external view returns (Listing[] memory, uint256 total) {
        CollectionListings storage collection = collectionListings[nftContract];
        uint256 length = collection.listings.length;
        
        if (offset >= length) {
            return (new Listing[](0), length);
        }
        
        uint256 remaining = length - offset;
        uint256 currentLimit = remaining < limit ? remaining : limit;
        
        Listing[] memory result = new Listing[](currentLimit);
        for (uint256 i = 0; i < currentLimit; i++) {
            result[i] = collection.listings[offset + i];
        }
        
        return (result, length);
    }

    function getCollectionRoyalty(
        address _nftContract
    ) external view returns (RoyaltyInfo memory) {
        return collectionRoyalties[_nftContract];
    }

    /* ========== IERC721Receiver ========== */

    function onERC721Received(
        address,
        address,
        uint256,
        bytes calldata
    ) external pure override returns (bytes4) {
        return this.onERC721Received.selector;
    }
}

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