// File: src/GachaAuction.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.7;

import "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/security/Pausable.sol";

import "./interfaces/IERC2981.sol";

contract GachaAuction is Ownable, Pausable, ReentrancyGuard {
    using Counters for Counters.Counter;

    struct Drop {
        address tokenAddress;
        uint256 price;
        uint64 notBefore;
        uint64 deadline;
        uint256[] tokenIds;
    }

    event DropCreated(address indexed seller, uint256 dropId);
    event RoyaltyWithheld(address royaltyRecipient, uint256 royaltyAmount);
    event Sale(uint256 indexed dropId, uint256 tokenId, address buyer);

    Counters.Counter private _dropIdCounter;
    mapping(uint256 => Drop) private drops;
    mapping(uint256 => address) public dropSellers;

    uint256 private _auctionFeeBps;

    constructor(uint256 auctionFeeBps_) Ownable() Pausable() ReentrancyGuard() {
        _auctionFeeBps = auctionFeeBps_;
    }

    /// @notice Given a drop struct, kicks off a new drop
    function setup(Drop calldata drop_) external whenNotPaused returns (uint256) {
        uint256 dropId = _dropIdCounter.current();
        drops[dropId] = drop_;
        dropSellers[dropId] = msg.sender;
        emit DropCreated(msg.sender, dropId);

        _dropIdCounter.increment();
        return dropId;
    }

    /// @notice Returns the next drop ID
    function nextDropId() public view returns (uint256) {
        return _dropIdCounter.current();
    }

    function peek(uint256 dropId) public view returns (Drop memory) {
        return drops[dropId];
    }

    /// @notice Buyer's interface, delivers to the caller
    function buy(uint256 dropId_) external payable whenNotPaused nonReentrant {
        _buy(dropId_, msg.sender);
    }

    /// @notice Buyer's interface, delivers to a specified address
    function buy(uint256 dropId_, address deliverTo_) external payable whenNotPaused nonReentrant {
        _buy(dropId_, deliverTo_);
    }

    function _buy(uint256 dropId_, address deliverTo_) private {
        // CHECKS
        Drop storage drop = drops[dropId_];

        require(drop.tokenAddress != address(0), "gacha: not found");
        require(drop.tokenIds.length > 0, "gacha: sold out");
        require(drop.notBefore <= block.timestamp, "gacha: auction not yet started");
        require(drop.deadline == 0 || drop.deadline >= block.timestamp, "gacha: auction already ended");

        require(msg.value == drop.price, "gacha: incorrect amount sent");

        // EFFECTS
        // Select token at (semi-)random
        uint256 tokenIdx = uint256(keccak256(abi.encodePacked(block.timestamp))) % drop.tokenIds.length;
        uint256 tokenId = drop.tokenIds[tokenIdx];

        // Remove the token from the drop tokens list
        drop.tokenIds[tokenIdx] = drop.tokenIds[drop.tokenIds.length - 1];
        drop.tokenIds.pop();

        (, address royaltyReceiver, uint256 royaltyAmount, uint256 sellerShare) = _getProceedsDistribution(
            dropSellers[dropId_],
            drop.tokenAddress,
            tokenId,
            drop.price
        );

        emit Sale(dropId_, tokenId, msg.sender);
        if (royaltyReceiver != address(0) && royaltyAmount > 0) {
            emit RoyaltyWithheld(royaltyReceiver, royaltyAmount);
        }

        // INTERACTIONS
        // Transfer the token and ensure delivery of the token
        IERC721(drop.tokenAddress).safeTransferFrom(dropSellers[dropId_], deliverTo_, tokenId);
        require(IERC721(drop.tokenAddress).ownerOf(tokenId) == deliverTo_, "gacha: token transfer failed"); // ensure delivery

        // Ensure delivery of the payment
        // solhint-disable-next-line avoid-low-level-calls
        (bool paymentSent, ) = dropSellers[dropId_].call{value: sellerShare}("");
        require(paymentSent, "gacha: seller payment failed");

        // Clean up the drop after all items have been sold
        if (drop.tokenIds.length == 0) {
            delete drops[dropId_];
        }
    }

    function _getProceedsDistribution(
        address seller_,
        address tokenAddress_,
        uint256 tokenId_,
        uint256 price_
    )
        private
        view
        returns (
            uint256 auctionFeeAmount,
            address royaltyReceiver,
            uint256 royaltyAmount,
            uint256 sellerShare
        )
    {
        // Auction fee
        auctionFeeAmount = (price_ * _auctionFeeBps) / 10000;

        // EIP-2981 royalty split
        (royaltyReceiver, royaltyAmount) = _getRoyaltyInfo(tokenAddress_, tokenId_, price_ - auctionFeeAmount);
        // No royalty address, or royalty goes to the seller
        if (royaltyReceiver == address(0) || royaltyReceiver == seller_) {
            royaltyAmount = 0;
        }

        // Seller's share
        sellerShare = price_ - (auctionFeeAmount + royaltyAmount);

        // Internal consistency check
        assert(sellerShare + auctionFeeAmount + royaltyAmount <= price_);
    }

    function _getRoyaltyInfo(
        address tokenAddress_,
        uint256 tokenId_,
        uint256 price_
    ) private view returns (address, uint256) {
        try IERC2981(tokenAddress_).royaltyInfo(tokenId_, price_) returns (
            address royaltyReceiver,
            uint256 royaltyAmount
        ) {
            return (royaltyReceiver, royaltyAmount);
        } catch (bytes memory reason) {
            // EIP 2981's `royaltyInfo()` function is not implemented
            // treatment the same as here: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.3.1/contracts/token/ERC721/ERC721.sol#L379
            if (reason.length == 0) {
                return (address(0), 0);
            } else {
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    revert(add(32, reason), mload(reason))
                }
            }
        }
    }

    /// @dev Auction fee setters and getters
    function auctionFeeBps() public view returns (uint256) {
        return _auctionFeeBps;
    }

    function setAuctionFeeBps(uint256 newAuctionFeeBps_) public onlyOwner {
        _auctionFeeBps = newAuctionFeeBps_;
    }

    /// @dev Auction fee & withheld royalty withdrawal
    function withdraw(address payable account_, uint256 amount_) public nonReentrant onlyOwner {
        // solhint-disable-next-line avoid-low-level-calls
        (bool paymentSent, ) = account_.call{value: amount_}("");
        require(paymentSent, "FixedPriceAuction: withdrawal failed");
    }

    /// @dev The following functions relate to pausing of the contract
    function pause() external onlyOwner {
        _pause();
    }

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

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

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

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

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

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

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

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @title Counters
 * @author Matt Condon (@shrugs)
 * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
 * of elements in a mapping, issuing ERC721 ids, or counting request ids.
 *
 * Include with `using Counters for Counters.Counter;`
 */
library Counters {
    struct Counter {
        // This variable should never be directly accessed by users of the library: interactions must be restricted to
        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
        // this feature: see https://github.com/ethereum/solidity/issues/4637
        uint256 _value; // default: 0
    }

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

    function increment(Counter storage counter) internal {
        unchecked {
            counter._value += 1;
        }
    }

    function decrement(Counter storage counter) internal {
        uint256 value = counter._value;
        require(value > 0, "Counter: decrement overflow");
        unchecked {
            counter._value = value - 1;
        }
    }

    function reset(Counter storage counter) internal {
        counter._value = 0;
    }
}

// File: @openzeppelin/contracts/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT

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 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: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _setOwner(_msgSender());
    }

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

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

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

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwner(newOwner);
    }

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

// File: @openzeppelin/contracts/security/Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

    bool private _paused;

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

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

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

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

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

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

// File: src/interfaces/IERC2981.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.7;

import "@openzeppelin/contracts/utils/introspection/IERC165.sol";

///
/// @dev Interface for EIP-2981: NFT Royalty Standard
///
interface IERC2981 is IERC165 {
    /**
     * @notice Called with the sale price to determine how much royalty
     *         is owed and to whom.
     * @param tokenId_ - the NFT asset queried for royalty information
     * @param salePrice_ - the sale price of the NFT asset specified by _tokenId
     * @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);
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

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