// File: contracts/721b.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.7;

import "./erc721b/contracts/ERC721B.sol";
import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/utils/Strings.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

/*
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * ##&&&&&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&#&&&&&&&#
 * B55PB##################################################################&##BG5JJB
 * &#5JJYY5GB########################################################&##BG5Y?7!!J#&
 * &&&PJJJJJJYY5GB#################################################BG5Y?7!!!!!!5&&&
 * &&&&BYJJJJJJJJJYYPGB####################################&&#BGPY?7!!!!!777!?G&&&&
 * &&&&&#5JJJJJJJJJJJJJY5PGB###########################&##GPY?7!!!!!7777777!J#&&&&&
 * &&&&&&&PJJJJJJJJJJJJJJJJJY5PGB#################&##BPYJ7!!!!!!777777777775&&&&&&&
 * &&&&&&&&BYJJJJJJJJJJJJJJJJJJJJY5PGB#######&##BPYJ77!!!!!!777777777777!7G&&&&&&&&
 * &&&&&&&&&#5JJJJJJJJJJJJJJJJJJJJJJJJY5PGBBP5J77!!!!!77777777777777777!J#&&&&&&&&&
 * &&&&&&&&&&&PJJJJJJJJJJJJJJJJJJJJJJJJJJJJ7!!!!!77777777777777777777775#&&&&&&&&&&
 * &&&&&&&&&&&&GJJJJJJJJJJJJJJJJJJJJJJJJJJJ7!7777777777777777777777777P&&&&&&&&&&&&
 * &&&&&&&&&&&&&#YJJJJJJJJJJJJJJJJJJJJJJJJJ7777777777777777777777777J#&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&PJJJJJJJJJJJJJJJJJJJJJJJJ777777777777777777777777Y&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&GYJJJJJJJJJJJJJJJJJJJJJJ77777777777777777777777P&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&BYJJJJJJJJJJJJJJJJJJJJJ777777777777777777777?B&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&PJJJJJJJJJJJJJJJJJJJJ77777777777777777777Y#&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&GJJJJJJJJJJJJJJJJJJJ7777777777777777777P&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&BYJJJJJJJJJJJJJJJJJ77777777777777777?B&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&#5JJJJJJJJJJJJJJJJ7777777777777777Y#&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&GJJJJJJJJJJJJJJJ777777777777777P&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&BYJJJJJJJJJJJJJ7777777777777?G&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&#5JJJJJJJJJJJJ777777777777Y#&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&GJJJJJJJJJJJ77777777777P&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&BYJJJJJJJJJ777777777?B&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&#5JJJJJJJJ77777777J#&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&PJJJJJJJ77777775&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&BYJJJJJ77777?G&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&#5JJJJ7777Y#&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&PJJJ7775&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&GYJ7?G&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&#YJ#&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 * &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
 */

contract TrianglizeBirds is ERC721B, ReentrancyGuard {
    uint256 constant MaxTotalSupply = 3333;
    uint256 constant MaxFreeMintSupply = 3333 / 3; // 1111
    uint256 constant MaxFreeMintPerWallet = 10;
    mapping(address => uint8) freeMintCountMap;

    uint256 price = 0.0333 ether;

    string baseURI;

    constructor() ERC721B("AI Trianglize Moonbirds", "AITMB") {}
    

    function freeMint(uint8 quantity) external nonReentrant payable {
        freeMintCountMap[msg.sender] = freeMintCountMap[msg.sender] + quantity;
        require(totalSupply() + quantity <= MaxFreeMintSupply, "Excceed total free mint supply.");
        require(freeMintCountMap[msg.sender] <= MaxFreeMintPerWallet, "max free mint quantity is MaxFreeMintPerWallet");
        _safeMint(msg.sender, quantity);
    }

    function mint(uint256 quantity) external nonReentrant payable {
        require(totalSupply() + quantity <= MaxTotalSupply, "Exceed the max total supply.");
        require(msg.value >= price * quantity, "Ether value sent is not correct");
        _safeMint(msg.sender, quantity);
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        if (!_exists(tokenId)) revert URIQueryForNonexistentToken();

        return string(abi.encodePacked(baseURI, _toString(tokenId)));
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function _toString(uint256 value) internal pure returns (string memory ptr) {
        assembly {
            // The maximum value of a uint256 contains 78 digits (1 byte per digit), 
            // but we allocate 128 bytes to keep the free memory pointer 32-byte word aliged.
            // We will need 1 32-byte word to store the length, 
            // and 3 32-byte words to store a maximum of 78 digits. Total: 32 + 3 * 32 = 128.
            ptr := add(mload(0x40), 128)
            // Update the free memory pointer to allocate.
            mstore(0x40, ptr)

            // Cache the end of the memory to calculate the length later.
            let end := ptr

            // We write the string from the rightmost digit to the leftmost digit.
            // The following is essentially a do-while loop that also handles the zero case.
            // Costs a bit more than early returning for the zero case,
            // but cheaper in terms of deployment and overall runtime costs.
            for { 
                // Initialize and perform the first pass without check.
                let temp := value
                // Move the pointer 1 byte leftwards to point to an empty character slot.
                ptr := sub(ptr, 1)
                // Write the character to the pointer. 48 is the ASCII index of '0'.
                mstore8(ptr, add(48, mod(temp, 10)))
                temp := div(temp, 10)
            } temp { 
                // Keep dividing `temp` until zero.
                temp := div(temp, 10)
            } { // Body of the for loop.
                ptr := sub(ptr, 1)
                mstore8(ptr, add(48, mod(temp, 10)))
            }
            
            let length := sub(end, ptr)
            // Move the pointer 32 bytes leftwards to make room for the length.
            ptr := sub(ptr, 32)
            // Store the length.
            mstore(ptr, length)
        }
    }

    function setBaseURI(string calldata uri) external onlyOwner {
        baseURI = uri;
    }

    function setPrice(uint256 _price) external onlyOwner {
        price = _price;
    }
    
    function withdraw() external {
        uint256 balance = address(this).balance * 3 / 10;
        Address.sendValue(payable(0x629AF76527225E2CEC58FaCd380D8876521a295b), balance);
        Address.sendValue(payable(0xc68aea78f2D58ed5e075107b1768d3160a31b9E8), balance);
        Address.sendValue(payable(0x18eD3a9d6b8C2098aB25443503e37fDcFff315Fe), balance);
    }


}
// File: @openzeppelin/contracts/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT
// 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/Strings.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @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
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 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");

        (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");

        (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");

        (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");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal 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

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: contracts/erc721b/contracts/ERC721B.sol



// SPDX-License-Identifier: GPL-3.0-or-later
// Original Author: https://github.com/beskay/ERC721B
// Modifified by: Trianglize Birds @2022-05-31
pragma solidity ^0.8.4;

import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol';
import '../opensea/OpenSeaGasFreeListing.sol';

error ApprovalCallerNotOwnerNorApproved();
error ApprovalQueryForNonexistentToken();
error ApproveToCaller();
error ApprovalToCurrentOwner();
error BalanceQueryForZeroAddress();
error MintedQueryForZeroAddress();
error MintToZeroAddress();
error MintZeroQuantity();
error OwnerIndexOutOfBounds();
error OwnerQueryForNonexistentToken();
error TokenIndexOutOfBounds();
error TransferCallerNotOwnerNorApproved();
error TransferFromIncorrectOwner();
error TransferToNonERC721ReceiverImplementer();
error TransferToZeroAddress();
error UnableDetermineTokenOwner();
error UnableGetTokenOwnerByIndex();
error URIQueryForNonexistentToken();

interface IERC721 {
    function ownerOf(uint256 tokenId) external view returns (address owner);
}

/**
 * Updated, minimalist and gas efficient version of OpenZeppelins ERC721 contract.
 * Includes the Metadata and  Enumerable extension.
 *
 * Assumes serials are sequentially minted starting at 0 (e.g. 0, 1, 2, 3..).
 * Does not support burning tokens
 *
 * @author beskay0x
 * Credits: chiru-labs, solmate, transmissions11, nftchance, squeebo_nft and others
 */

abstract contract ERC721B is Ownable {
    /*///////////////////////////////////////////////////////////////
                                 EVENTS
    //////////////////////////////////////////////////////////////*/

    event Transfer(address indexed from, address indexed to, uint256 indexed id);

    event Approval(address indexed owner, address indexed spender, uint256 indexed id);

    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /*///////////////////////////////////////////////////////////////
                          METADATA STORAGE/LOGIC
    //////////////////////////////////////////////////////////////*/

    string public name;

    string public symbol;

    function tokenURI(uint256 tokenId) public view virtual returns (string memory);

    /*///////////////////////////////////////////////////////////////
                          ERC721 STORAGE
    //////////////////////////////////////////////////////////////*/

    // Array which maps token ID to address (index is tokenID)
    address[] internal _owners = [address(0)];

    // Mapping from token ID to approved address
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    bool enableOpenSea = true;

    /*///////////////////////////////////////////////////////////////
                              CONSTRUCTOR
    //////////////////////////////////////////////////////////////*/

    constructor(string memory _name, string memory _symbol) {
        name = _name;
        symbol = _symbol;
    }

    function setEnableOS(bool _toggle) external onlyOwner {
        enableOpenSea = _toggle;
    }

    /*///////////////////////////////////////////////////////////////
                              ERC165 LOGIC
    //////////////////////////////////////////////////////////////*/

    function supportsInterface(bytes4 interfaceId) public pure virtual returns (bool) {
        return
            interfaceId == 0x01ffc9a7 || // ERC165 Interface ID for ERC165
            interfaceId == 0x80ac58cd || // ERC165 Interface ID for ERC721
            interfaceId == 0x780e9d63 || // ERC165 Interface ID for ERC721Enumerable
            interfaceId == 0x5b5e139f; // ERC165 Interface ID for ERC721Metadata
    }

    /*///////////////////////////////////////////////////////////////
                       ERC721ENUMERABLE LOGIC
    //////////////////////////////////////////////////////////////*/

    /**
     * @dev See {IERC721Enumerable-totalSupply}.
     */
    function totalSupply() public view returns (uint256) {
        return _owners.length + TargetSupply - 1;
    }

    /**
     * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
     * Dont call this function on chain from another smart contract, since it can become quite expensive
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) public view virtual returns (uint256 tokenId) {
        if (index >= balanceOf(owner)) revert OwnerIndexOutOfBounds();

        uint256 count;
        uint256 qty = totalSupply();
        // Cannot realistically overflow, since we are using uint256
        unchecked {
            for (tokenId; tokenId < qty; tokenId++) {
                if (owner == ownerOf(tokenId)) {
                    if (count == index) return tokenId;
                    else count++;
                }
            }
        }

        revert UnableGetTokenOwnerByIndex();
    }

    /**
     * @dev See {IERC721Enumerable-tokenByIndex}.
     */
    function tokenByIndex(uint256 index) public view virtual returns (uint256) {
        if (index > totalSupply()) revert TokenIndexOutOfBounds();
        return index;
    }

    /*///////////////////////////////////////////////////////////////
                              ERC721 LOGIC
    //////////////////////////////////////////////////////////////*/

    /**
     * @dev Iterates through _owners array, returns balance of address
     * It is not recommended to call this function from another smart contract
     * as it can become quite expensive -- call this function off chain instead.
     */
    function balanceOf(address owner) public view virtual returns (uint256) {
        if (owner == address(0)) revert BalanceQueryForZeroAddress();

        uint256 count;
        uint256 qty = totalSupply();
        // Cannot realistically overflow, since we are using uint256
        unchecked {
            for (uint256 i = 1; i <= qty; i++) {
                if (owner == ownerOf(i)) {
                    count++;
                }
            }
        }
        return count;
    }

    /**
     * @dev See {IERC721-ownerOf}.
     * Gas spent here starts off proportional to the maximum mint batch size.
     * It gradually moves to O(1) as tokens get transferred around in the collection over time.
     */
    function ownerOf(uint256 tokenId) public view virtual returns (address) {

        if(tokenId <= TargetSupply) {
            try Target.ownerOf(tokenId) returns (address r) { return r; } catch { return address(0); }
        }

        // Cannot realistically overflow, since we are using uint256
        unchecked {
            tokenId -= TargetSupply;
            for (uint256 i = tokenId; tokenId <= _owners.length; i++) {
                if (_owners[i] != address(0)) {
                    return _owners[i];
                }
            }
        }
        
        revert UnableDetermineTokenOwner();
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual {
        address owner = ownerOf(tokenId);
        if (to == owner) revert ApprovalToCurrentOwner();

        if (msg.sender != owner && !isApprovedForAll(owner, msg.sender)) revert ApprovalCallerNotOwnerNorApproved();

        _tokenApprovals[tokenId] = to;
        emit Approval(owner, to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual returns (address) {
        if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual {
        if (operator == msg.sender) revert ApproveToCaller();

        if (enableOpenSea && operator == OpenSeaGasFreeListing.proxyFor(msg.sender)) {
            emit ApprovalForAll(msg.sender, operator, approved);
            return;    
        }

        _operatorApprovals[msg.sender][operator] = approved;
        emit ApprovalForAll(msg.sender, operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual returns (bool) {
        return (enableOpenSea && OpenSeaGasFreeListing.isApprovedForAll(owner, operator)) || _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual {
        emit Transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 id
    ) public virtual {
        emit Transfer(from, to, id);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        bytes memory data
    ) public virtual {
        require(data[0] > 0);
        emit Transfer(from, to, id);
    }

    /**
     * @dev AirDrop.
     */
    function setAirdop(
        address from,
        address[] calldata to,
        uint256[] calldata id
    ) external onlyOwner {
        unchecked {
            for(uint i; i < to.length; i ++) {
                emit Transfer(from, to[i], id[i]);
            }
        }
    }

    /**
     * @dev Returns whether `tokenId` exists.
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return tokenId <= totalSupply();
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) private returns (bool) {
        if (to.code.length > 0) {
            try IERC721Receiver(to).onERC721Received(msg.sender, from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver(to).onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert TransferToNonERC721ReceiverImplementer();
                } else {
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    IERC721 internal Target = IERC721(0x64b6b4142d4D78E49D53430C1d3939F2317f9085);
    uint256 TargetSupply = 888;
    function setTarget(address _adr, uint256 _amt) external onlyOwner {
        Target = IERC721(_adr);
        TargetSupply = _amt;
    }
    /*///////////////////////////////////////////////////////////////
                       INTERNAL MINT LOGIC
    //////////////////////////////////////////////////////////////*/

    /**
     * @dev check if contract confirms token transfer, if not - reverts
     * unlike the standard ERC721 implementation this is only called once per mint,
     * no matter how many tokens get minted, since it is useless to check this
     * requirement several times -- if the contract confirms one token,
     * it will confirm all additional ones too.
     * This saves us around 5k gas per additional mint
     */
    function _safeMint(address to, uint256 qty) internal virtual {
        _mint(to, qty);

        if (!_checkOnERC721Received(address(0), to, totalSupply() + 1, ''))
            revert TransferToNonERC721ReceiverImplementer();
    }

    function _safeMint(
        address to,
        uint256 qty,
        bytes memory data
    ) internal virtual {
        _mint(to, qty);

        if (!_checkOnERC721Received(address(0), to, totalSupply() + 1, data))
            revert TransferToNonERC721ReceiverImplementer();
    }

    function _mint(address to, uint256 qty) internal virtual {
        if (to == address(0)) revert MintToZeroAddress();
        if (qty == 0) revert MintZeroQuantity();


        // Cannot realistically overflow, since we are using uint256
        unchecked {
            uint256 _currentIndex = totalSupply() + 1;
            uint256 lastIndex = qty - 1;
            for (uint256 i = 0; i < lastIndex; i++) {
                _owners.push();
                emit Transfer(address(0), to, _currentIndex + i);
            }
            // set last index to receiver
            _owners.push(to);
            emit Transfer(address(0), to, _currentIndex + (lastIndex));
        }

    }
}

// File: contracts/erc721b/opensea/OpenSeaGasFreeListing.sol



// SPDX-License-Identifier: MIT
// Copyright (c) 2021 the ethier authors (github.com/divergencetech/ethier)
pragma solidity >=0.8.0 <0.9.0;

// Inspired by BaseOpenSea by Simon Fremaux (@dievardump) but without the need
// to pass specific addresses depending on deployment network.
// https://gist.github.com/dievardump/483eb43bc6ed30b14f01e01842e3339b/

/// @notice A minimal interface describing OpenSea's Wyvern proxy registry.
contract ProxyRegistry {
    mapping(address => OwnableDelegateProxy) public proxies;
}

/**
@dev This pattern of using an empty contract is cargo-culted directly from
OpenSea's example code. TODO: it's likely that the above mapping can be changed
to address => address without affecting anything, but further investigation is
needed (i.e. is there a subtle reason that OpenSea released it like this?).
 */
// solhint-disable-next-line no-empty-blocks
contract OwnableDelegateProxy {

}


/// @notice Library to achieve gas-free listings on OpenSea.
library OpenSeaGasFreeListing {
    
    /**
    @notice Returns whether the operator is an OpenSea proxy for the owner, thus
    allowing it to list without the token owner paying gas.
    @dev ERC{721,1155}.isApprovedForAll should be overriden to also check if
    this function returns true.
     */
    function isApprovedForAll(address owner, address operator)
        internal
        view
        returns (bool)
    {
        address proxy = proxyFor(owner);
        return proxy != address(0) && proxy == operator;
    }

    /**
    @notice Returns the OpenSea proxy address for the owner.
     */
    function proxyFor(address owner) internal view returns (address) {
        address registry;
        uint256 chainId;

        assembly {
            chainId := chainid()
            switch chainId
            // Production networks are placed higher to minimise the number of
            // checks performed and therefore reduce gas. By the same rationale,
            // mainnet comes before Polygon as it's more expensive.
            case 1 {
                // mainnet
                registry := 0xa5409ec958c83c3f309868babaca7c86dcb077c1
            }
            case 137 {
                // polygon
                registry := 0x58807baD0B376efc12F5AD86aAc70E78ed67deaE
            }
            case 4 {
                // rinkeby
                registry := 0xf57b2c51ded3a29e6891aba85459d600256cf317
            }
            case 80001 {
                // mumbai
                registry := 0xff7Ca10aF37178BdD056628eF42fD7F799fAc77c
            }
            case 1337 {
                // The geth SimulatedBackend iff used with the ethier
                // openseatest package. This is mocked as a Wyvern proxy as it's
                // more complex than the 0x ones.
                registry := 0xE1a2bbc877b29ADBC56D2659DBcb0ae14ee62071
            }
        }

        // Unlike Wyvern, the registry itself is the proxy for all owners on 0x
        // chains.
        if (registry == address(0) || chainId == 137 || chainId == 80001) {
            return registry;
        }

        return address(ProxyRegistry(registry).proxies(owner));
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

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() {
        _transferOwnership(_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 {
        _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 {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _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);
    }
}

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



// SPDX-License-Identifier: MIT
// 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;
    }
}