// File: contracts/NftMint721A.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.0 <0.9.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Strings.sol";
import "./ERC721A.sol";

//String_Ownable_IERCmetadata_ERC165_IERC165_context_ERC721_IERC721

contract JustASquareERC721A is ERC721A, Ownable {
	using Strings for uint256;

	string public uriPrefix = "";
	string public uriSuffix = ".json";

	uint256 private cost = 0.01 ether;
	uint256 private costFree = 0;
	uint256 public maxSupply = 2000;
	uint256 public maxSupplyFree = 1000;
	uint256 public maxMintAmountPerTx = 10;
	uint256 public maxMintPerWallet = 20;

	bool public paused = true;

	constructor(string memory _tokenName, string memory _symbol) ERC721A(_tokenName, _symbol) {}

	modifier mintCompliance(uint256 _mintAmount) {
		require(_mintAmount > 0 && _mintAmount <= maxMintAmountPerTx, "Invalid mint amount!");
		require(totalSupply() + _mintAmount <= maxSupply, "Max supply exceeded!");
		require(balanceOf(msg.sender) + _mintAmount <= maxMintPerWallet, "Max supply for your wallet exceeded!");
		_;
	}

	function mint(uint256 _mintAmount) public payable mintCompliance(_mintAmount) {
		require(!paused, "The contract is paused!");
		if (totalSupply() + _mintAmount <= maxSupplyFree) {
			_safeMint(msg.sender, _mintAmount);
		} else {
			require(msg.value >= cost * _mintAmount, "Insufficient funds!");
			_safeMint(msg.sender, _mintAmount);
		}
	}

	function gift(uint256 _mintAmount, address _receiver) public onlyOwner {
		require(totalSupply() + _mintAmount <= maxSupply, "Max supply exceeded!");
		_safeMint(_receiver, _mintAmount);
	}

	function walletOfOwner(address _owner) public view returns (uint256[] memory) {
		uint256 ownerTokenCount = balanceOf(_owner);
		uint256[] memory ownedTokenIds = new uint256[](ownerTokenCount);
		uint256 currentTokenId = 1;
		uint256 ownedTokenIndex = 0;

		while (ownedTokenIndex < ownerTokenCount && currentTokenId <= totalSupply()) {
			address currentTokenOwner = ownerOf(currentTokenId);

			if (currentTokenOwner == _owner) {
				ownedTokenIds[ownedTokenIndex] = currentTokenId;

				ownedTokenIndex++;
			}

			currentTokenId++;
		}

		return ownedTokenIds;
	}

	function tokenURI(uint256 _tokenId) public view virtual override returns (string memory) {
		require(_exists(_tokenId), "ERC721Metadata: URI query for nonexistent token");

		string memory currentBaseURI = _baseURI();
		return bytes(currentBaseURI).length > 0 ? string(abi.encodePacked(currentBaseURI, _tokenId.toString(), uriSuffix)) : "";
	}

	function setCost(uint256 _cost) public onlyOwner {
		cost = _cost;
	}

	function getCost() public view returns (uint256) {
		if (totalSupply() < maxSupplyFree) {
			return costFree;
		}
		return cost;
	}

	function setMaxMintAmountPerTx(uint256 _maxMintAmountPerTx) public onlyOwner {
		maxMintAmountPerTx = _maxMintAmountPerTx;
	}

	function setUriPrefix(string memory _uriPrefix) public onlyOwner {
		uriPrefix = _uriPrefix;
	}

	function setUriSuffix(string memory _uriSuffix) public onlyOwner {
		uriSuffix = _uriSuffix;
	}

	function setPaused(bool _state) public onlyOwner {
		paused = _state;
	}

	function withdraw() public onlyOwner {
		// This will transfer the remaining contract balance to the owner.
		(bool os, ) = payable(owner()).call{ value: address(this).balance }("");
		require(os);
	}

	function withdrawAmount(uint256 _amount) public onlyOwner {
		require(_amount <= address(this).balance, "not enought in contract");
		(bool os, ) = payable(owner()).call{ value: _amount }("");
		require(os);
	}

	function _baseURI() internal view virtual override returns (string memory) {
		return uriPrefix;
	}

	function _startTokenId() internal view virtual override returns (uint256) {
		return 1;
	}
}

// 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/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: contracts/ERC721A.sol



// SPDX-License-Identifier: MIT
// ERC721A Contracts v4.0.0
// Creator: Chiru Labs

pragma solidity ^0.8.4;

import "./IERC721A.sol";

//ERC721Metadata -> IERC721A
//ERC165 -> IERC72A

/**
 * @dev ERC721 token receiver interface.
 */
interface ERC721A__IERC721Receiver {
	function onERC721Received(
		address operator,
		address from,
		uint256 tokenId,
		bytes calldata data
	) external returns (bytes4);
}

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension. Built to optimize for lower gas during batch mints.
 *
 * Assumes serials are sequentially minted starting at _startTokenId() (defaults to 0, e.g. 0, 1, 2, 3..).
 *
 * Assumes that an owner cannot have more than 2**64 - 1 (max value of uint64) of supply.
 *
 * Assumes that the maximum token id cannot exceed 2**256 - 1 (max value of uint256).
 */
contract ERC721A is IERC721A {
	// Mask of an entry in packed address data.
	uint256 private constant BITMASK_ADDRESS_DATA_ENTRY = (1 << 64) - 1;

	// The bit position of `numberMinted` in packed address data.
	uint256 private constant BITPOS_NUMBER_MINTED = 64;

	// The bit position of `numberBurned` in packed address data.
	uint256 private constant BITPOS_NUMBER_BURNED = 128;

	// The bit position of `aux` in packed address data.
	uint256 private constant BITPOS_AUX = 192;

	// Mask of all 256 bits in packed address data except the 64 bits for `aux`.
	uint256 private constant BITMASK_AUX_COMPLEMENT = (1 << 192) - 1;

	// The bit position of `startTimestamp` in packed ownership.
	uint256 private constant BITPOS_START_TIMESTAMP = 160;

	// The bit mask of the `burned` bit in packed ownership.
	uint256 private constant BITMASK_BURNED = 1 << 224;

	// The bit position of the `nextInitialized` bit in packed ownership.
	uint256 private constant BITPOS_NEXT_INITIALIZED = 225;

	// The bit mask of the `nextInitialized` bit in packed ownership.
	uint256 private constant BITMASK_NEXT_INITIALIZED = 1 << 225;

	// The bit position of `extraData` in packed ownership.
	uint256 private constant BITPOS_EXTRA_DATA = 232;

	// The mask of the lower 160 bits for addresses.
	uint256 private constant BITMASK_ADDRESS = (1 << 160) - 1;

	// The maximum `quantity` that can be minted with `_mintERC2309`.
	// This limit is to prevent overflows on the address data entries.
	// For a limit of 5000, a total of 3.689e15 calls to `_mintERC2309`
	// is required to cause an overflow, which is unrealistic.
	uint256 private constant MAX_MINT_ERC2309_QUANTITY_LIMIT = 5000;

	// The tokenId of the next token to be minted.
	uint256 private _currentIndex;

	// The number of tokens burned.
	uint256 private _burnCounter;

	// Token name
	string private _name;

	// Token symbol
	string private _symbol;

	// Mapping from token ID to ownership details
	// An empty struct value does not necessarily mean the token is unowned.
	// See `_packedOwnershipOf` implementation for details.
	//
	// Bits Layout:
	// - [0..159]   `addr`
	// - [160..223] `startTimestamp`
	// - [224]      `burned`
	// - [225]      `nextInitialized`
	// - [232..255] `extraData`
	mapping(uint256 => uint256) private _packedOwnerships;

	// Mapping owner address to address data.
	//
	// Bits Layout:
	// - [0..63]    `balance`
	// - [64..127]  `numberMinted`
	// - [128..191] `numberBurned`
	// - [192..255] `aux`
	mapping(address => uint256) private _packedAddressData;

	// 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;

	constructor(string memory name_, string memory symbol_) {
		_name = name_;
		_symbol = symbol_;
		_currentIndex = _startTokenId();
	}

	/**
	 * @dev Returns the starting token ID.
	 * To change the starting token ID, please override this function.
	 */
	function _startTokenId() internal view virtual returns (uint256) {
		return 0;
	}

	/**
	 * @dev Returns the next token ID to be minted.
	 */
	function _nextTokenId() internal view returns (uint256) {
		return _currentIndex;
	}

	/**
	 * @dev Returns the total number of tokens in existence.
	 * Burned tokens will reduce the count.
	 * To get the total number of tokens minted, please see `_totalMinted`.
	 */
	function totalSupply() public view override returns (uint256) {
		// Counter underflow is impossible as _burnCounter cannot be incremented
		// more than `_currentIndex - _startTokenId()` times.
		unchecked {
			return _currentIndex - _burnCounter - _startTokenId();
		}
	}

	/**
	 * @dev Returns the total amount of tokens minted in the contract.
	 */
	function _totalMinted() internal view returns (uint256) {
		// Counter underflow is impossible as _currentIndex does not decrement,
		// and it is initialized to `_startTokenId()`
		unchecked {
			return _currentIndex - _startTokenId();
		}
	}

	/**
	 * @dev Returns the total number of tokens burned.
	 */
	function _totalBurned() internal view returns (uint256) {
		return _burnCounter;
	}

	/**
	 * @dev See {IERC165-supportsInterface}.
	 */
	function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
		// The interface IDs are constants representing the first 4 bytes of the XOR of
		// all function selectors in the interface. See: https://eips.ethereum.org/EIPS/eip-165
		// e.g. `bytes4(i.functionA.selector ^ i.functionB.selector ^ ...)`
		return
			interfaceId == 0x01ffc9a7 || // ERC165 interface ID for ERC165.
			interfaceId == 0x80ac58cd || // ERC165 interface ID for ERC721.
			interfaceId == 0x5b5e139f; // ERC165 interface ID for ERC721Metadata.
	}

	/**
	 * @dev See {IERC721-balanceOf}.
	 */
	function balanceOf(address owner) public view override returns (uint256) {
		if (owner == address(0)) revert BalanceQueryForZeroAddress();
		return _packedAddressData[owner] & BITMASK_ADDRESS_DATA_ENTRY;
	}

	/**
	 * Returns the number of tokens minted by `owner`.
	 */
	function _numberMinted(address owner) internal view returns (uint256) {
		return (_packedAddressData[owner] >> BITPOS_NUMBER_MINTED) & BITMASK_ADDRESS_DATA_ENTRY;
	}

	/**
	 * Returns the number of tokens burned by or on behalf of `owner`.
	 */
	function _numberBurned(address owner) internal view returns (uint256) {
		return (_packedAddressData[owner] >> BITPOS_NUMBER_BURNED) & BITMASK_ADDRESS_DATA_ENTRY;
	}

	/**
	 * Returns the auxiliary data for `owner`. (e.g. number of whitelist mint slots used).
	 */
	function _getAux(address owner) internal view returns (uint64) {
		return uint64(_packedAddressData[owner] >> BITPOS_AUX);
	}

	/**
	 * Sets the auxiliary data for `owner`. (e.g. number of whitelist mint slots used).
	 * If there are multiple variables, please pack them into a uint64.
	 */
	function _setAux(address owner, uint64 aux) internal {
		uint256 packed = _packedAddressData[owner];
		uint256 auxCasted;
		assembly {
			// Cast aux without masking.
			auxCasted := aux
		}
		packed = (packed & BITMASK_AUX_COMPLEMENT) | (auxCasted << BITPOS_AUX);
		_packedAddressData[owner] = packed;
	}

	/**
	 * Returns the packed ownership data of `tokenId`.
	 */
	function _packedOwnershipOf(uint256 tokenId) private view returns (uint256) {
		uint256 curr = tokenId;

		unchecked {
			if (_startTokenId() <= curr)
				if (curr < _currentIndex) {
					uint256 packed = _packedOwnerships[curr];
					// If not burned.
					if (packed & BITMASK_BURNED == 0) {
						// Invariant:
						// There will always be an ownership that has an address and is not burned
						// before an ownership that does not have an address and is not burned.
						// Hence, curr will not underflow.
						//
						// We can directly compare the packed value.
						// If the address is zero, packed is zero.
						while (packed == 0) {
							packed = _packedOwnerships[--curr];
						}
						return packed;
					}
				}
		}
		revert OwnerQueryForNonexistentToken();
	}

	/**
	 * Returns the unpacked `TokenOwnership` struct from `packed`.
	 */
	function _unpackedOwnership(uint256 packed) private pure returns (TokenOwnership memory ownership) {
		ownership.addr = address(uint160(packed));
		ownership.startTimestamp = uint64(packed >> BITPOS_START_TIMESTAMP);
		ownership.burned = packed & BITMASK_BURNED != 0;
		ownership.extraData = uint24(packed >> BITPOS_EXTRA_DATA);
	}

	/**
	 * Returns the unpacked `TokenOwnership` struct at `index`.
	 */
	function _ownershipAt(uint256 index) internal view returns (TokenOwnership memory) {
		return _unpackedOwnership(_packedOwnerships[index]);
	}

	/**
	 * @dev Initializes the ownership slot minted at `index` for efficiency purposes.
	 */
	function _initializeOwnershipAt(uint256 index) internal {
		if (_packedOwnerships[index] == 0) {
			_packedOwnerships[index] = _packedOwnershipOf(index);
		}
	}

	/**
	 * 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 _ownershipOf(uint256 tokenId) internal view returns (TokenOwnership memory) {
		return _unpackedOwnership(_packedOwnershipOf(tokenId));
	}

	/**
	 * @dev Packs ownership data into a single uint256.
	 */
	function _packOwnershipData(address owner, uint256 flags) private view returns (uint256 result) {
		assembly {
			// Mask `owner` to the lower 160 bits, in case the upper bits somehow aren't clean.
			owner := and(owner, BITMASK_ADDRESS)
			// `owner | (block.timestamp << BITPOS_START_TIMESTAMP) | flags`.
			result := or(owner, or(shl(BITPOS_START_TIMESTAMP, timestamp()), flags))
		}
	}

	/**
	 * @dev See {IERC721-ownerOf}.
	 */
	function ownerOf(uint256 tokenId) public view override returns (address) {
		return address(uint160(_packedOwnershipOf(tokenId)));
	}

	/**
	 * @dev See {IERC721Metadata-name}.
	 */
	function name() public view virtual override returns (string memory) {
		return _name;
	}

	/**
	 * @dev See {IERC721Metadata-symbol}.
	 */
	function symbol() public view virtual override returns (string memory) {
		return _symbol;
	}

	/**
	 * @dev See {IERC721Metadata-tokenURI}.
	 */
	function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
		if (!_exists(tokenId)) revert URIQueryForNonexistentToken();

		string memory baseURI = _baseURI();
		return bytes(baseURI).length != 0 ? string(abi.encodePacked(baseURI, _toString(tokenId))) : "";
	}

	/**
	 * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
	 * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
	 * by default, it can be overridden in child contracts.
	 */
	function _baseURI() internal view virtual returns (string memory) {
		return "";
	}

	/**
	 * @dev Casts the boolean to uint256 without branching.
	 */
	function _boolToUint256(bool value) private pure returns (uint256 result) {
		assembly {
			result := value
		}
	}

	/**
	 * @dev See {IERC721-approve}.
	 */
	function approve(address to, uint256 tokenId) public override {
		address owner = ownerOf(tokenId);

		if (_msgSenderERC721A() != owner)
			if (!isApprovedForAll(owner, _msgSenderERC721A())) {
				revert ApprovalCallerNotOwnerNorApproved();
			}

		_tokenApprovals[tokenId] = to;
		emit Approval(owner, to, tokenId);
	}

	/**
	 * @dev See {IERC721-getApproved}.
	 */
	function getApproved(uint256 tokenId) public view override returns (address) {
		if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();

		return _tokenApprovals[tokenId];
	}

	/**
	 * @dev See {IERC721-setApprovalForAll}.
	 */
	function setApprovalForAll(address operator, bool approved) public virtual override {
		if (operator == _msgSenderERC721A()) revert ApproveToCaller();

		_operatorApprovals[_msgSenderERC721A()][operator] = approved;
		emit ApprovalForAll(_msgSenderERC721A(), operator, approved);
	}

	/**
	 * @dev See {IERC721-isApprovedForAll}.
	 */
	function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
		return _operatorApprovals[owner][operator];
	}

	/**
	 * @dev See {IERC721-safeTransferFrom}.
	 */
	function safeTransferFrom(
		address from,
		address to,
		uint256 tokenId
	) public virtual override {
		safeTransferFrom(from, to, tokenId, "");
	}

	/**
	 * @dev See {IERC721-safeTransferFrom}.
	 */
	function safeTransferFrom(
		address from,
		address to,
		uint256 tokenId,
		bytes memory _data
	) public virtual override {
		transferFrom(from, to, tokenId);
		if (to.code.length != 0)
			if (!_checkContractOnERC721Received(from, to, tokenId, _data)) {
				revert TransferToNonERC721ReceiverImplementer();
			}
	}

	/**
	 * @dev Returns whether `tokenId` exists.
	 *
	 * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
	 *
	 * Tokens start existing when they are minted (`_mint`),
	 */
	function _exists(uint256 tokenId) internal view returns (bool) {
		return
			_startTokenId() <= tokenId &&
			tokenId < _currentIndex && // If within bounds,
			_packedOwnerships[tokenId] & BITMASK_BURNED == 0; // and not burned.
	}

	/**
	 * @dev Equivalent to `_safeMint(to, quantity, '')`.
	 */
	function _safeMint(address to, uint256 quantity) internal {
		_safeMint(to, quantity, "");
	}

	/**
	 * @dev Safely mints `quantity` tokens and transfers them to `to`.
	 *
	 * Requirements:
	 *
	 * - If `to` refers to a smart contract, it must implement
	 *   {IERC721Receiver-onERC721Received}, which is called for each safe transfer.
	 * - `quantity` must be greater than 0.
	 *
	 * See {_mint}.
	 *
	 * Emits a {Transfer} event for each mint.
	 */
	function _safeMint(
		address to,
		uint256 quantity,
		bytes memory _data
	) internal {
		_mint(to, quantity);

		unchecked {
			if (to.code.length != 0) {
				uint256 end = _currentIndex;
				uint256 index = end - quantity;
				do {
					if (!_checkContractOnERC721Received(address(0), to, index++, _data)) {
						revert TransferToNonERC721ReceiverImplementer();
					}
				} while (index < end);
				// Reentrancy protection.
				if (_currentIndex != end) revert();
			}
		}
	}

	/**
	 * @dev Mints `quantity` tokens and transfers them to `to`.
	 *
	 * Requirements:
	 *
	 * - `to` cannot be the zero address.
	 * - `quantity` must be greater than 0.
	 *
	 * Emits a {Transfer} event for each mint.
	 */
	function _mint(address to, uint256 quantity) internal {
		uint256 startTokenId = _currentIndex;
		if (to == address(0)) revert MintToZeroAddress();
		if (quantity == 0) revert MintZeroQuantity();

		_beforeTokenTransfers(address(0), to, startTokenId, quantity);

		// Overflows are incredibly unrealistic.
		// `balance` and `numberMinted` have a maximum limit of 2**64.
		// `tokenId` has a maximum limit of 2**256.
		unchecked {
			// Updates:
			// - `balance += quantity`.
			// - `numberMinted += quantity`.
			//
			// We can directly add to the `balance` and `numberMinted`.
			_packedAddressData[to] += quantity * ((1 << BITPOS_NUMBER_MINTED) | 1);

			// Updates:
			// - `address` to the owner.
			// - `startTimestamp` to the timestamp of minting.
			// - `burned` to `false`.
			// - `nextInitialized` to `quantity == 1`.
			_packedOwnerships[startTokenId] = _packOwnershipData(to, (_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED) | _nextExtraData(address(0), to, 0));

			uint256 tokenId = startTokenId;
			uint256 end = quantity + startTokenId;
			do {
				emit Transfer(address(0), to, tokenId++);
			} while (tokenId < end);

			_currentIndex = startTokenId + quantity;
		}
		_afterTokenTransfers(address(0), to, startTokenId, quantity);
	}

	/**
	 * @dev Mints `quantity` tokens and transfers them to `to`.
	 *
	 * This function is intended for efficient minting only during contract creation.
	 *
	 * It emits only one {ConsecutiveTransfer} as defined in
	 * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309),
	 * instead of a sequence of {Transfer} event(s).
	 *
	 * Calling this function outside of contract creation WILL make your contract
	 * non-compliant with the ERC721 standard.
	 * For full ERC721 compliance, substituting ERC721 {Transfer} event(s) with the ERC2309
	 * {ConsecutiveTransfer} event is only permissible during contract creation.
	 *
	 * Requirements:
	 *
	 * - `to` cannot be the zero address.
	 * - `quantity` must be greater than 0.
	 *
	 * Emits a {ConsecutiveTransfer} event.
	 */
	function _mintERC2309(address to, uint256 quantity) internal {
		uint256 startTokenId = _currentIndex;
		if (to == address(0)) revert MintToZeroAddress();
		if (quantity == 0) revert MintZeroQuantity();
		if (quantity > MAX_MINT_ERC2309_QUANTITY_LIMIT) revert MintERC2309QuantityExceedsLimit();

		_beforeTokenTransfers(address(0), to, startTokenId, quantity);

		// Overflows are unrealistic due to the above check for `quantity` to be below the limit.
		unchecked {
			// Updates:
			// - `balance += quantity`.
			// - `numberMinted += quantity`.
			//
			// We can directly add to the `balance` and `numberMinted`.
			_packedAddressData[to] += quantity * ((1 << BITPOS_NUMBER_MINTED) | 1);

			// Updates:
			// - `address` to the owner.
			// - `startTimestamp` to the timestamp of minting.
			// - `burned` to `false`.
			// - `nextInitialized` to `quantity == 1`.
			_packedOwnerships[startTokenId] = _packOwnershipData(to, (_boolToUint256(quantity == 1) << BITPOS_NEXT_INITIALIZED) | _nextExtraData(address(0), to, 0));

			emit ConsecutiveTransfer(startTokenId, startTokenId + quantity - 1, address(0), to);

			_currentIndex = startTokenId + quantity;
		}
		_afterTokenTransfers(address(0), to, startTokenId, quantity);
	}

	/**
	 * @dev Returns the storage slot and value for the approved address of `tokenId`.
	 */
	function _getApprovedAddress(uint256 tokenId) private view returns (uint256 approvedAddressSlot, address approvedAddress) {
		mapping(uint256 => address) storage tokenApprovalsPtr = _tokenApprovals;
		// The following is equivalent to `approvedAddress = _tokenApprovals[tokenId]`.
		assembly {
			// Compute the slot.
			mstore(0x00, tokenId)
			mstore(0x20, tokenApprovalsPtr.slot)
			approvedAddressSlot := keccak256(0x00, 0x40)
			// Load the slot's value from storage.
			approvedAddress := sload(approvedAddressSlot)
		}
	}

	/**
	 * @dev Returns whether the `approvedAddress` is equals to `from` or `msgSender`.
	 */
	function _isOwnerOrApproved(
		address approvedAddress,
		address from,
		address msgSender
	) private pure returns (bool result) {
		assembly {
			// Mask `from` to the lower 160 bits, in case the upper bits somehow aren't clean.
			from := and(from, BITMASK_ADDRESS)
			// Mask `msgSender` to the lower 160 bits, in case the upper bits somehow aren't clean.
			msgSender := and(msgSender, BITMASK_ADDRESS)
			// `msgSender == from || msgSender == approvedAddress`.
			result := or(eq(msgSender, from), eq(msgSender, approvedAddress))
		}
	}

	/**
	 * @dev Transfers `tokenId` from `from` to `to`.
	 *
	 * Requirements:
	 *
	 * - `to` cannot be the zero address.
	 * - `tokenId` token must be owned by `from`.
	 *
	 * Emits a {Transfer} event.
	 */
	function transferFrom(
		address from,
		address to,
		uint256 tokenId
	) public virtual override {
		uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);

		if (address(uint160(prevOwnershipPacked)) != from) revert TransferFromIncorrectOwner();

		(uint256 approvedAddressSlot, address approvedAddress) = _getApprovedAddress(tokenId);

		// The nested ifs save around 20+ gas over a compound boolean condition.
		if (!_isOwnerOrApproved(approvedAddress, from, _msgSenderERC721A()))
			if (!isApprovedForAll(from, _msgSenderERC721A())) revert TransferCallerNotOwnerNorApproved();

		if (to == address(0)) revert TransferToZeroAddress();

		_beforeTokenTransfers(from, to, tokenId, 1);

		// Clear approvals from the previous owner.
		assembly {
			if approvedAddress {
				// This is equivalent to `delete _tokenApprovals[tokenId]`.
				sstore(approvedAddressSlot, 0)
			}
		}

		// Underflow of the sender's balance is impossible because we check for
		// ownership above and the recipient's balance can't realistically overflow.
		// Counter overflow is incredibly unrealistic as tokenId would have to be 2**256.
		unchecked {
			// We can directly increment and decrement the balances.
			--_packedAddressData[from]; // Updates: `balance -= 1`.
			++_packedAddressData[to]; // Updates: `balance += 1`.

			// Updates:
			// - `address` to the next owner.
			// - `startTimestamp` to the timestamp of transfering.
			// - `burned` to `false`.
			// - `nextInitialized` to `true`.
			_packedOwnerships[tokenId] = _packOwnershipData(to, BITMASK_NEXT_INITIALIZED | _nextExtraData(from, to, prevOwnershipPacked));

			// If the next slot may not have been initialized (i.e. `nextInitialized == false`) .
			if (prevOwnershipPacked & BITMASK_NEXT_INITIALIZED == 0) {
				uint256 nextTokenId = tokenId + 1;
				// If the next slot's address is zero and not burned (i.e. packed value is zero).
				if (_packedOwnerships[nextTokenId] == 0) {
					// If the next slot is within bounds.
					if (nextTokenId != _currentIndex) {
						// Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.
						_packedOwnerships[nextTokenId] = prevOwnershipPacked;
					}
				}
			}
		}

		emit Transfer(from, to, tokenId);
		_afterTokenTransfers(from, to, tokenId, 1);
	}

	/**
	 * @dev Equivalent to `_burn(tokenId, false)`.
	 */
	function _burn(uint256 tokenId) internal virtual {
		_burn(tokenId, false);
	}

	/**
	 * @dev Destroys `tokenId`.
	 * The approval is cleared when the token is burned.
	 *
	 * Requirements:
	 *
	 * - `tokenId` must exist.
	 *
	 * Emits a {Transfer} event.
	 */
	function _burn(uint256 tokenId, bool approvalCheck) internal virtual {
		uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);

		address from = address(uint160(prevOwnershipPacked));

		(uint256 approvedAddressSlot, address approvedAddress) = _getApprovedAddress(tokenId);

		if (approvalCheck)
			if (!_isOwnerOrApproved(approvedAddress, from, _msgSenderERC721A()))
				if (!isApprovedForAll(from, _msgSenderERC721A()))
					// The nested ifs save around 20+ gas over a compound boolean condition.
					revert TransferCallerNotOwnerNorApproved();

		_beforeTokenTransfers(from, address(0), tokenId, 1);

		// Clear approvals from the previous owner.
		assembly {
			if approvedAddress {
				// This is equivalent to `delete _tokenApprovals[tokenId]`.
				sstore(approvedAddressSlot, 0)
			}
		}

		// Underflow of the sender's balance is impossible because we check for
		// ownership above and the recipient's balance can't realistically overflow.
		// Counter overflow is incredibly unrealistic as `tokenId` would have to be 2**256.
		unchecked {
			// Updates:
			// - `balance -= 1`.
			// - `numberBurned += 1`.
			//
			// We can directly decrement the balance, and increment the number burned.
			// This is equivalent to `packed -= 1; packed += 1 << BITPOS_NUMBER_BURNED;`.
			_packedAddressData[from] += (1 << BITPOS_NUMBER_BURNED) - 1;

			// Updates:
			// - `address` to the last owner.
			// - `startTimestamp` to the timestamp of burning.
			// - `burned` to `true`.
			// - `nextInitialized` to `true`.
			_packedOwnerships[tokenId] = _packOwnershipData(from, (BITMASK_BURNED | BITMASK_NEXT_INITIALIZED) | _nextExtraData(from, address(0), prevOwnershipPacked));

			// If the next slot may not have been initialized (i.e. `nextInitialized == false`) .
			if (prevOwnershipPacked & BITMASK_NEXT_INITIALIZED == 0) {
				uint256 nextTokenId = tokenId + 1;
				// If the next slot's address is zero and not burned (i.e. packed value is zero).
				if (_packedOwnerships[nextTokenId] == 0) {
					// If the next slot is within bounds.
					if (nextTokenId != _currentIndex) {
						// Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.
						_packedOwnerships[nextTokenId] = prevOwnershipPacked;
					}
				}
			}
		}

		emit Transfer(from, address(0), tokenId);
		_afterTokenTransfers(from, address(0), tokenId, 1);

		// Overflow not possible, as _burnCounter cannot be exceed _currentIndex times.
		unchecked {
			_burnCounter++;
		}
	}

	/**
	 * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target 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 _checkContractOnERC721Received(
		address from,
		address to,
		uint256 tokenId,
		bytes memory _data
	) private returns (bool) {
		try ERC721A__IERC721Receiver(to).onERC721Received(_msgSenderERC721A(), from, tokenId, _data) returns (bytes4 retval) {
			return retval == ERC721A__IERC721Receiver(to).onERC721Received.selector;
		} catch (bytes memory reason) {
			if (reason.length == 0) {
				revert TransferToNonERC721ReceiverImplementer();
			} else {
				assembly {
					revert(add(32, reason), mload(reason))
				}
			}
		}
	}

	/**
	 * @dev Returns the next extra data for the packed ownership data.
	 * The returned result is shifted into position.
	 */
	function _nextExtraData(
		address from,
		address to,
		uint256 prevOwnershipPacked
	) internal view virtual returns (uint256) {
		uint24 previousExtraData;
		assembly {
			previousExtraData := shr(BITPOS_EXTRA_DATA, prevOwnershipPacked)
		}
		return uint256(_extraData(from, to, previousExtraData)) << BITPOS_EXTRA_DATA;
	}

	/**
	 * @dev Called during each token transfer to set the 24bit `extraData` field.
	 * Intended to be overridden by the cosumer contract.
	 *
	 * `previousExtraData` - the value of `extraData` before transfer.
	 *
	 * Calling conditions:
	 *
	 * - When `from` and `to` are both non-zero, `from`'s `tokenId` will be
	 * transferred to `to`.
	 * - When `from` is zero, `tokenId` will be minted for `to`.
	 * - When `to` is zero, `tokenId` will be burned by `from`.
	 * - `from` and `to` are never both zero.
	 */
	function _extraData(
		address from,
		address to,
		uint24 previousExtraData
	) internal view virtual returns (uint24) {}

	/**
	 * @dev Hook that is called before a set of serially-ordered token ids are about to be transferred. This includes minting.
	 * And also called before burning one token.
	 *
	 * startTokenId - the first token id to be transferred
	 * quantity - the amount to be transferred
	 *
	 * Calling conditions:
	 *
	 * - When `from` and `to` are both non-zero, `from`'s `tokenId` will be
	 * transferred to `to`.
	 * - When `from` is zero, `tokenId` will be minted for `to`.
	 * - When `to` is zero, `tokenId` will be burned by `from`.
	 * - `from` and `to` are never both zero.
	 */
	function _beforeTokenTransfers(
		address from,
		address to,
		uint256 startTokenId,
		uint256 quantity
	) internal virtual {}

	/**
	 * @dev Hook that is called after a set of serially-ordered token ids have been transferred. This includes
	 * minting.
	 * And also called after one token has been burned.
	 *
	 * startTokenId - the first token id to be transferred
	 * quantity - the amount to be transferred
	 *
	 * Calling conditions:
	 *
	 * - When `from` and `to` are both non-zero, `from`'s `tokenId` has been
	 * transferred to `to`.
	 * - When `from` is zero, `tokenId` has been minted for `to`.
	 * - When `to` is zero, `tokenId` has been burned by `from`.
	 * - `from` and `to` are never both zero.
	 */
	function _afterTokenTransfers(
		address from,
		address to,
		uint256 startTokenId,
		uint256 quantity
	) internal virtual {}

	/**
	 * @dev Returns the message sender (defaults to `msg.sender`).
	 *
	 * If you are writing GSN compatible contracts, you need to override this function.
	 */
	function _msgSenderERC721A() internal view virtual returns (address) {
		return msg.sender;
	}

	/**
	 * @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)
		}
	}
}

// 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;
    }
}

// File: contracts/IERC721A.sol



// SPDX-License-Identifier: MIT
// ERC721A Contracts v4.0.0
// Creator: Chiru Labs

pragma solidity ^0.8.4;

/**
 * @dev Interface of an ERC721A compliant contract.
 */
interface IERC721A {
	/**
	 * The caller must own the token or be an approved operator.
	 */
	error ApprovalCallerNotOwnerNorApproved();

	/**
	 * The token does not exist.
	 */
	error ApprovalQueryForNonexistentToken();

	/**
	 * The caller cannot approve to their own address.
	 */
	error ApproveToCaller();

	/**
	 * Cannot query the balance for the zero address.
	 */
	error BalanceQueryForZeroAddress();

	/**
	 * Cannot mint to the zero address.
	 */
	error MintToZeroAddress();

	/**
	 * The quantity of tokens minted must be more than zero.
	 */
	error MintZeroQuantity();

	/**
	 * The token does not exist.
	 */
	error OwnerQueryForNonexistentToken();

	/**
	 * The caller must own the token or be an approved operator.
	 */
	error TransferCallerNotOwnerNorApproved();

	/**
	 * The token must be owned by `from`.
	 */
	error TransferFromIncorrectOwner();

	/**
	 * Cannot safely transfer to a contract that does not implement the ERC721Receiver interface.
	 */
	error TransferToNonERC721ReceiverImplementer();

	/**
	 * Cannot transfer to the zero address.
	 */
	error TransferToZeroAddress();

	/**
	 * The token does not exist.
	 */
	error URIQueryForNonexistentToken();

	/**
	 * The `quantity` minted with ERC2309 exceeds the safety limit.
	 */
	error MintERC2309QuantityExceedsLimit();

	struct TokenOwnership {
		// The address of the owner.
		address addr;
		// Keeps track of the start time of ownership with minimal overhead for tokenomics.
		uint64 startTimestamp;
		// Whether the token has been burned.
		bool burned;
		// Arbitrary data similar to `startTimestamp` that can be set through `_extraData`.
		uint24 extraData;
	}

	/**
	 * @dev Returns the total amount of tokens stored by the contract.
	 *
	 * Burned tokens are calculated here, use `_totalMinted()` if you want to count just minted tokens.
	 */
	function totalSupply() external view returns (uint256);

	// ==============================
	//            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);

	// ==============================
	//            IERC721
	// ==============================

	/**
	 * @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 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 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 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);

	// ==============================
	//        IERC721Metadata
	// ==============================

	/**
	 * @dev Returns the token collection name.
	 */
	function name() external view returns (string memory);

	/**
	 * @dev Returns the token collection symbol.
	 */
	function symbol() external view returns (string memory);

	/**
	 * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
	 */
	function tokenURI(uint256 tokenId) external view returns (string memory);

	// ==============================
	//            IERC2309
	// ==============================

	/**
	 * @dev Emitted when tokens in `fromTokenId` to `toTokenId` (inclusive) is transferred from `from` to `to`,
	 * as defined in the ERC2309 standard. See `_mintERC2309` for more details.
	 */
	event ConsecutiveTransfer(uint256 indexed fromTokenId, uint256 toTokenId, address indexed from, address indexed to);
}