// SPDX-License-Identifier: MIT

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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);
}





/**
 * @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;
}





/**
 * @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 `IERC721.onERC721Received.selector`.
	 */
	function onERC721Received(
		address operator,
		address from,
		uint256 tokenId,
		bytes calldata data
	) external returns (bytes4);
}





/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
	/**
	 * @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);
}

// File: @openzeppelin/contracts/utils/Address.sol




/**
 * @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);
			}
		}
	}
}





/**
 * @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;
	}
}





/**
 * @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);
	}
}





/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
	/**
	 * @dev See {IERC165-supportsInterface}.
	 */
	function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
		return interfaceId == type(IERC165).interfaceId;
	}
}





/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721A] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721A is Context, ERC165, IERC721, IERC721Metadata {
	using Address for address;
	using Strings for uint256;


	uint256 private currentIndex = 0;
	uint256 public maxBatchSize = 35;

	// Token name
	string private _name;

	// Token symbol
	string private _symbol;

	// Mapping from token ID to owner address
	mapping(uint256 => address) private _owners;

	// Mapping owner address to token count
	mapping(address => uint256) private _balances;

	// 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;

	/**
	 * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
	 */
	constructor(string memory name_, string memory symbol_) {
		_name = name_;
		_symbol = symbol_;
	}

	/**
	 * @dev See {IERC165-supportsInterface}.
	 */
	function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
		return
			interfaceId == type(IERC721).interfaceId ||
			interfaceId == type(IERC721Metadata).interfaceId ||
			super.supportsInterface(interfaceId);
	}

	/**
	 * @dev See {IERC721-balanceOf}.
	 */
	function balanceOf(address owner) public view virtual override returns (uint256) {
		require(owner != address(0), "ERC721A: balance query for the zero address");
		return _balances[owner];
	}

	function ownerOf(uint256 tokenId) public view virtual override returns (address) {
		require(_exists(tokenId), "ERC721A: owner query for nonexistent token");

		uint256 lowestTokenToCheck;
		if (tokenId >= maxBatchSize) {
			lowestTokenToCheck = tokenId - maxBatchSize + 1;
		}

		for (uint256 curr = tokenId; curr >= lowestTokenToCheck; curr--) {
			address owner = _owners[curr];
			if (owner != address(0)) {
				return owner;
			}
		}

		revert("ERC721A: unable to determine the owner of token");
	}

	/**
	 * @dev See {IERC721-ownerOf}.
	 */
	// function ownerOf(uint256 tokenId) public view virtual override returns (address) {
	//     return ownershipOf(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) {
		require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");

		string memory baseURI = _baseURI();
		return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
	}

	/**
	 * @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, can be overriden in child contracts.
	 */
	function _baseURI() internal view virtual returns (string memory) {
		return "";
	}

	/**
	 * @dev See {IERC721-approve}.
	 */
	function approve(address to, uint256 tokenId) public virtual override {
		address owner = ERC721A.ownerOf(tokenId);
		require(to != owner, "ERC721A: approval to current owner");

		require(
			_msgSender() == owner || isApprovedForAll(owner, _msgSender()),
			"ERC721A: approve caller is not owner nor approved for all"
		);

		_approve(to, tokenId);
	}

	/**
	 * @dev See {IERC721-getApproved}.
	 */
	function getApproved(uint256 tokenId) public view virtual override returns (address) {
		require(_exists(tokenId), "ERC721A: approved query for nonexistent token");

		return _tokenApprovals[tokenId];
	}

	/**
	 * @dev See {IERC721-setApprovalForAll}.
	 */
	function setApprovalForAll(address operator, bool approved) public virtual override {
		_setApprovalForAll(_msgSender(), 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-transferFrom}.
	 */
	function transferFrom(
		address from,
		address to,
		uint256 tokenId
	) public virtual override {
		//solhint-disable-next-line max-line-length
		require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721A: transfer caller is not owner nor approved");

		_transfer(from, to, tokenId);
	}

	/**
	 * @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 {
		require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721A: transfer caller is not owner nor approved");
		_safeTransfer(from, to, tokenId, _data);
	}

	/**
	 * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
	 * are aware of the ERC721A protocol to prevent tokens from being forever locked.
	 *
	 * `_data` is additional data, it has no specified format and it is sent in call to `to`.
	 *
	 * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
	 * implement alternative mechanisms to perform token transfer, such as signature-based.
	 *
	 * Requirements:
	 *
	 * - `from` cannot be the zero address.
	 * - `to` cannot be the zero address.
	 * - `tokenId` token must exist and be owned by `from`.
	 * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
	 *
	 * Emits a {Transfer} event.
	 */
	function _safeTransfer(
		address from,
		address to,
		uint256 tokenId,
		bytes memory _data
	) internal virtual {
		_transfer(from, to, tokenId);
		require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721A: transfer to non ERC721Receiver implementer");
	}

	/**
	 * @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`),
	 * and stop existing when they are burned (`_burn`).
	 */
	function _exists(uint256 tokenId) internal view virtual returns (bool) {
		return tokenId < currentIndex;
	}

	/**
	 * @dev Returns whether `spender` is allowed to manage `tokenId`.
	 *
	 * Requirements:
	 *
	 * - `tokenId` must exist.
	 */
	function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
		require(_exists(tokenId), "ERC721A: operator query for nonexistent token");
		address owner = ERC721A.ownerOf(tokenId);
		return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
	}

	/**
	 * @dev Safely mints `tokenId` and transfers it to `to`.
	 *
	 * Requirements:
	 *
	 * - `tokenId` must not exist.
	 * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
	 *
	 * Emits a {Transfer} event.
	 */
	function _safeMint(address to, uint256 quantity) internal virtual {
		_safeMint(to, quantity, "");
	}

	/**
	 * @dev Same as {xref-ERC721A-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
	 * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
	 */
	function _safeMint(
		address to,
		uint256 quantity,
		bytes memory _data
	) internal virtual {
		uint256 startTokenId = currentIndex;
		require(to != address(0), "ERC721A: mint to the zero address");
		require(!_exists(startTokenId), "ERC721A: token already minted");

		_beforeTokenTransfers(address(0), to, startTokenId, quantity);

		_balances[to] += quantity;
		_owners[startTokenId] =to;

		uint256 updatedIndex = startTokenId;

		for (uint256 i = 0; i < quantity; i++) {
			emit Transfer(address(0), to, updatedIndex);
			require(
				_checkOnERC721Received(address(0), to, updatedIndex, _data),
				"ERC721A: transfer to non ERC721Receiver implementer"
			);
			updatedIndex++;
		}

		currentIndex = updatedIndex;

		_afterTokenTransfers(address(0), to, startTokenId, quantity);
	}

	/**
	 * @dev Destroys `tokenId`.
	 * The approval is cleared when the token is burned.
	 *
	 * Requirements:
	 *
	 * - `tokenId` must exist.
	 *
	 * Emits a {Transfer} event.
	 */
	function _burn(uint256 tokenId) internal virtual {
		address owner = ERC721A.ownerOf(tokenId);

		_beforeTokenTransfer(owner, address(0), tokenId);

		// Clear approvals
		_approve(address(0), tokenId);

		_balances[owner] -= 1;
		delete _owners[tokenId];

		emit Transfer(owner, address(0), tokenId);

		_afterTokenTransfer(owner, address(0), tokenId);
	}

	/**
	 * @dev Transfers `tokenId` from `from` to `to`.
	 *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
	 *
	 * Requirements:
	 *
	 * - `to` cannot be the zero address.
	 * - `tokenId` token must be owned by `from`.
	 *
	 * Emits a {Transfer} event.
	 */
	function _transfer(
		address from,
		address to,
		uint256 tokenId
	) internal virtual {
		require(ERC721A.ownerOf(tokenId) == from, "ERC721A: transfer from incorrect owner");
		require(to != address(0), "ERC721A: transfer to the zero address");

		_beforeTokenTransfer(from, to, tokenId);

		// Clear approvals from the previous owner
		_approve(address(0), tokenId);

		_balances[from] -= 1;
		_balances[to] += 1;
		_owners[tokenId] = to;
		if(_owners[tokenId+1] == address(0))
			_owners[tokenId+1] = from;

		emit Transfer(from, to, tokenId);

		_afterTokenTransfer(from, to, tokenId);
	}

	/**
	 * @dev Approve `to` to operate on `tokenId`
	 *
	 * Emits a {Approval} event.
	 */
	function _approve(address to, uint256 tokenId) internal virtual {
		_tokenApprovals[tokenId] = to;
		emit Approval(ERC721A.ownerOf(tokenId), to, tokenId);
	}

	/**
	 * @dev Approve `operator` to operate on all of `owner` tokens
	 *
	 * Emits a {ApprovalForAll} event.
	 */
	function _setApprovalForAll(
		address owner,
		address operator,
		bool approved
	) internal virtual {
		require(owner != operator, "ERC721A: approve to caller");
		_operatorApprovals[owner][operator] = approved;
		emit ApprovalForAll(owner, operator, approved);
	}

	/**
	 * @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.isContract()) {
			try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
				return retval == IERC721Receiver.onERC721Received.selector;
			} catch (bytes memory reason) {
				if (reason.length == 0) {
					revert("ERC721A: transfer to non ERC721Receiver implementer");
				} else {
					assembly {
						revert(add(32, reason), mload(reason))
					}
				}
			}
		} else {
			return true;
		}
	}

	function getTotalSupply() public view returns(uint256) {
		return currentIndex;
	}
	/**
	 * @dev Hook that is called before any token transfer. This includes minting
	 * and burning.
	 *
	 * 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, ``from``'s `tokenId` will be burned.
	 * - `from` and `to` are never both zero.
	 *
	 * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
	 */
	function _beforeTokenTransfer(
		address from,
		address to,
		uint256 tokenId
	) internal virtual {}

	/**
	 * @dev Hook that is called after any transfer of tokens. This includes
	 * minting and burning.
	 *
	 * Calling conditions:
	 *
	 * - when `from` and `to` are both non-zero.
	 * - `from` and `to` are never both zero.
	 *
	 * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
	 */
	function _afterTokenTransfer(
		address from,
		address to,
		uint256 tokenId
	) internal virtual {}

	function _beforeTokenTransfers(
		address from,
		address to,
		uint256 startTokenId,
		uint256 quantity
	) internal virtual {}

	function _afterTokenTransfers(
		address from,
		address to,
		uint256 startTokenId,
		uint256 quantity
	) internal virtual {}
}





/**
 * @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);
	}
}





/**
 * @dev These functions deal with verification of Merkle Trees proofs.
 *
 * The proofs can be generated using the JavaScript library
 * https://github.com/miguelmota/merkletreejs[merkletreejs].
 * Note: the hashing algorithm should be keccak256 and pair sorting should be enabled.
 *
 * See `test/utils/cryptography/MerkleProof.test.js` for some examples.
 */
library MerkleProof {
	/**
	 * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
	 * defined by `root`. For this, a `proof` must be provided, containing
	 * sibling hashes on the branch from the leaf to the root of the tree. Each
	 * pair of leaves and each pair of pre-images are assumed to be sorted.
	 */
	function verify(
		bytes32[] memory proof,
		bytes32 root,
		bytes32 leaf
	) internal pure returns (bool) {
		return processProof(proof, leaf) == root;
	}

	/**
	 * @dev Returns the rebuilt hash obtained by traversing a Merklee tree up
	 * from `leaf` using `proof`. A `proof` is valid if and only if the rebuilt
	 * hash matches the root of the tree. When processing the proof, the pairs
	 * of leafs & pre-images are assumed to be sorted.
	 *
	 * _Available since v4.4._
	 */
	function processProof(bytes32[] memory proof, bytes32 leaf) internal pure returns (bytes32) {
		bytes32 computedHash = leaf;
		for (uint256 i = 0; i < proof.length; i++) {
			bytes32 proofElement = proof[i];
			if (computedHash <= proofElement) {
				// Hash(current computed hash + current element of the proof)
				computedHash = _efficientHash(computedHash, proofElement);
			} else {
				// Hash(current element of the proof + current computed hash)
				computedHash = _efficientHash(proofElement, computedHash);
			}
		}
		return computedHash;
	}

	function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
		assembly {
			mstore(0x00, a)
			mstore(0x20, b)
			value := keccak256(0x00, 0x40)
		}
	}
}





/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
	/**
	 * @dev Returns the addition of two unsigned integers, with an overflow flag.
	 *
	 * _Available since v3.4._
	 */
	function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
		unchecked {
			uint256 c = a + b;
			if (c < a) return (false, 0);
			return (true, c);
		}
	}

	/**
	 * @dev Returns the substraction of two unsigned integers, with an overflow flag.
	 *
	 * _Available since v3.4._
	 */
	function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
		unchecked {
			if (b > a) return (false, 0);
			return (true, a - b);
		}
	}

	/**
	 * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
	 *
	 * _Available since v3.4._
	 */
	function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
		unchecked {
			// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
			// benefit is lost if 'b' is also tested.
			// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
			if (a == 0) return (true, 0);
			uint256 c = a * b;
			if (c / a != b) return (false, 0);
			return (true, c);
		}
	}

	/**
	 * @dev Returns the division of two unsigned integers, with a division by zero flag.
	 *
	 * _Available since v3.4._
	 */
	function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
		unchecked {
			if (b == 0) return (false, 0);
			return (true, a / b);
		}
	}

	/**
	 * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
	 *
	 * _Available since v3.4._
	 */
	function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
		unchecked {
			if (b == 0) return (false, 0);
			return (true, a % b);
		}
	}

	/**
	 * @dev Returns the addition of two unsigned integers, reverting on
	 * overflow.
	 *
	 * Counterpart to Solidity's `+` operator.
	 *
	 * Requirements:
	 *
	 * - Addition cannot overflow.
	 */
	function add(uint256 a, uint256 b) internal pure returns (uint256) {
		return a + b;
	}

	/**
	 * @dev Returns the subtraction of two unsigned integers, reverting on
	 * overflow (when the result is negative).
	 *
	 * Counterpart to Solidity's `-` operator.
	 *
	 * Requirements:
	 *
	 * - Subtraction cannot overflow.
	 */
	function sub(uint256 a, uint256 b) internal pure returns (uint256) {
		return a - b;
	}

	/**
	 * @dev Returns the multiplication of two unsigned integers, reverting on
	 * overflow.
	 *
	 * Counterpart to Solidity's `*` operator.
	 *
	 * Requirements:
	 *
	 * - Multiplication cannot overflow.
	 */
	function mul(uint256 a, uint256 b) internal pure returns (uint256) {
		return a * b;
	}

	/**
	 * @dev Returns the integer division of two unsigned integers, reverting on
	 * division by zero. The result is rounded towards zero.
	 *
	 * Counterpart to Solidity's `/` operator.
	 *
	 * Requirements:
	 *
	 * - The divisor cannot be zero.
	 */
	function div(uint256 a, uint256 b) internal pure returns (uint256) {
		return a / b;
	}

	/**
	 * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
	 * reverting when dividing by zero.
	 *
	 * Counterpart to Solidity's `%` operator. This function uses a `revert`
	 * opcode (which leaves remaining gas untouched) while Solidity uses an
	 * invalid opcode to revert (consuming all remaining gas).
	 *
	 * Requirements:
	 *
	 * - The divisor cannot be zero.
	 */
	function mod(uint256 a, uint256 b) internal pure returns (uint256) {
		return a % b;
	}

	/**
	 * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
	 * overflow (when the result is negative).
	 *
	 * CAUTION: This function is deprecated because it requires allocating memory for the error
	 * message unnecessarily. For custom revert reasons use {trySub}.
	 *
	 * Counterpart to Solidity's `-` operator.
	 *
	 * Requirements:
	 *
	 * - Subtraction cannot overflow.
	 */
	function sub(
		uint256 a,
		uint256 b,
		string memory errorMessage
	) internal pure returns (uint256) {
		unchecked {
			require(b <= a, errorMessage);
			return a - b;
		}
	}

	/**
	 * @dev Returns the integer division of two unsigned integers, reverting with custom message on
	 * division by zero. The result is rounded towards zero.
	 *
	 * Counterpart to Solidity's `/` operator. Note: this function uses a
	 * `revert` opcode (which leaves remaining gas untouched) while Solidity
	 * uses an invalid opcode to revert (consuming all remaining gas).
	 *
	 * Requirements:
	 *
	 * - The divisor cannot be zero.
	 */
	function div(
		uint256 a,
		uint256 b,
		string memory errorMessage
	) internal pure returns (uint256) {
		unchecked {
			require(b > 0, errorMessage);
			return a / b;
		}
	}

	/**
	 * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
	 * reverting with custom message when dividing by zero.
	 *
	 * CAUTION: This function is deprecated because it requires allocating memory for the error
	 * message unnecessarily. For custom revert reasons use {tryMod}.
	 *
	 * Counterpart to Solidity's `%` operator. This function uses a `revert`
	 * opcode (which leaves remaining gas untouched) while Solidity uses an
	 * invalid opcode to revert (consuming all remaining gas).
	 *
	 * Requirements:
	 *
	 * - The divisor cannot be zero.
	 */
	function mod(
		uint256 a,
		uint256 b,
		string memory errorMessage
	) internal pure returns (uint256) {
		unchecked {
			require(b > 0, errorMessage);
			return a % b;
		}
	}
}





contract Companions is ERC721A, Ownable
{
	using SafeMath for uint256;

	IERC721 starContract;

	string public baseURI;
	string public provenanceHash;

	uint256 public maxSupply = 10000;
	uint256 public maxBatchAmount = 400;

	uint256 public holderMintedAmount;
	uint256 public adminMintedAmount;
	uint256 public whitelistMintedAmount;
	uint256 public publicMintedAmount;

	uint256 public whitelistMintPrice = 0.042 ether;
	uint256 public publicMintPrice;
	uint256 public publicMaxPerTransaction = 10;
	uint256 public startingIndexBlock;
	uint256 public startingIndex;

	bool public holderMintActive = false;
	bool public whitelistMintActive = false;
	bool public publicMintActive = false;

	mapping(uint256 => bool) public usedStarIds;
	mapping(uint256 => uint256) public matchStarComp;
	mapping(address => bool) public mintedWhitelist;

	bytes32 private whitelistRoot;
	bytes32 private tieredWhitelistRoot;


	/**
	* @dev TheSolaVerse: Companions
	*/
	constructor() ERC721A("The SolaVerse: Companions", "Companion") {}


	/**
	* @dev Calculate the total amount minted so far.
	*/
	function totalSupply() public view returns (uint256)
	{
		return holderMintedAmount.add(adminMintedAmount).add(whitelistMintedAmount).add(publicMintedAmount);
	}


	/**
	* @dev SOLA-STAR holder wallets.
	*/
	function holderMint(uint256[] memory _ids) public
	{
		require(holderMintActive, "Holder mint is paused.");
		require(_ids.length <= maxBatchAmount, "Can't mint that many.");

		for (uint256 i=0; i<_ids.length; i++)
		{
			require(starContract.ownerOf(_ids[i]) == msg.sender, "You don't own this one.");
			require(!usedStarIds[_ids[i]], "This one was already used for minting.");
		}

		_safeMint(msg.sender, _ids.length);

		for (uint256 i=0; i<_ids.length; i++)
		{
			usedStarIds[_ids[i]] = true;
			matchStarComp[_ids[i]] = holderMintedAmount + i;
		}

		holderMintedAmount += _ids.length;
	}


	/**
	* @dev Whitelisted wallets.
	*/
	function whitelistMint(bytes32[] memory _proof, uint256 _num_tokens) public payable
	{
		require(whitelistMintActive, "Whitelist mint is paused.");
		require(mintedWhitelist[msg.sender] == false, "Already minted.");
		require(msg.value == _num_tokens.mul(whitelistMintPrice), "Insufficient funds.");

		bytes32 leaf = keccak256(abi.encodePacked(msg.sender));
		require(MerkleProof.verify(_proof, whitelistRoot, leaf), "Invalid proof.");

		_safeMint(msg.sender, _num_tokens);

		whitelistMintedAmount += _num_tokens;
		mintedWhitelist[msg.sender] = true;
	}


	/**
	* @dev Whitelisted wallets with Tiers.
	*/
	function tieredWhitelistMint(bytes32[] memory _proof, uint256 _num_tokens) public payable
	{
		require(whitelistMintActive, "Whitelist mint is paused.");
		require(mintedWhitelist[msg.sender] == false, "Already minted.");
		require(msg.value == _num_tokens.mul(whitelistMintPrice), "Insufficient funds.");

		bytes32 leaf = keccak256(abi.encodePacked(msg.sender, _num_tokens));
		require(MerkleProof.verify(_proof, tieredWhitelistRoot, leaf), "Invalid proof.");

		_safeMint(msg.sender, _num_tokens);

		whitelistMintedAmount += _num_tokens;
		mintedWhitelist[msg.sender] = true;
	}


	/**
	* @dev Public mint.
	*/
	function publicMint(uint256 _num_tokens) public payable
	{
		require(publicMintActive, "Public mint is paused.");
		require(publicMintPrice > 0, "Public mint price not set.");
		require(msg.value == publicMintPrice.mul(_num_tokens), "Insufficient funds.");
		require(_num_tokens <= publicMaxPerTransaction, "Can't mint that many at once.");
		require(totalSupply().add(_num_tokens) <= maxSupply, "Can't mint that many.");

		_safeMint(msg.sender, _num_tokens);

		publicMintedAmount += _num_tokens;

		if (startingIndexBlock == 0 && (totalSupply() == maxSupply))
		{
			startingIndexBlock = block.number;
		}
	}


	/**
	* @dev Admin mint.
	*/
	function adminMint(address _to, uint256 _num_tokens) public onlyOwner
	{
		require(_num_tokens <= maxBatchAmount, "Can't mint that many.");

		_safeMint(_to, _num_tokens);

		adminMintedAmount += _num_tokens;
	}


	/**
	* @dev Link to the SOLA-STAR NFT contract to check ownership during holderMint.
	*/
	function setStarContract(address _addr) public onlyOwner
	{
		starContract = IERC721(_addr);
	}


	/**
	* @dev Set the Merkle Root for the Whitelist.
	*/
	function setWhitelistMerkleRoot(bytes32 _root) public onlyOwner
	{
		whitelistRoot = _root;
	}


	/**
	* @dev Set the Merkle Root for the Tiered Whitelist.
	*/
	function setTieredWhitelistMerkleRoot(bytes32 _root) public onlyOwner
	{
		tieredWhitelistRoot = _root;
	}


	/**
	* @dev Toggle the Holder Mint status.
	*/
	function toggleHolderMint() public onlyOwner
	{
		holderMintActive = !holderMintActive;
	}


	/**
	* @dev Toggle the Whitelist Mint status.
	*/
	function toggleWhitelistMint() public onlyOwner
	{
		whitelistMintActive = !whitelistMintActive;
	}


	/**
	* @dev Toggle the Public Mint status.
	*/
	function togglepublicMint() public onlyOwner
	{
		publicMintActive = !publicMintActive;
	}


	/**
	* @dev Set the cost of the tokens for the public mint.
	*/
	function setPublicMintPrice(uint256 _price) public onlyOwner
	{
		publicMintPrice = _price;
	}


	/**
	* @dev Update the BaseURI for the reveals.
	*/
	function setBaseURI(string memory _newBaseURI) public onlyOwner
	{
		baseURI = _newBaseURI;
	}


	/**
	* @dev Get the Base URI.
	*/
	function _baseURI() internal view virtual override returns (string memory)
	{
		return baseURI;
	}


	/**
	 * @dev Finalize starting index.
	 */
	function finalizeStartingIndex() public onlyOwner
	{
		require(startingIndex == 0, "Starting index already set.");
		require(startingIndexBlock != 0, "Starting index block not set.");

		startingIndex = uint256(blockhash(startingIndexBlock)) % maxSupply;

		if (block.number.sub(startingIndexBlock) > 255)
		{
			startingIndex = uint256(blockhash(block.number.sub(1))) % maxSupply;
		}

		if (startingIndex == 0)
		{
			startingIndex = startingIndex.add(1);
		}
	}


	/**
	 * @dev Set the starting index block for the collection, essentially unblocking setting starting index.
	 */
	function emergencySetStartingIndexBlock() public onlyOwner
	{
		require(startingIndex == 0, "Starting index already set.");

		startingIndexBlock = block.number;
	}


	/**
	 * @dev Set provenance once it's calculated.
	 *
	 * @param _provenance_hash string memory
	 */
	function setProvenanceHash(string memory _provenance_hash) public onlyOwner
	{
		provenanceHash = _provenance_hash;
	}


	/**
	* @dev Withdraw the balance from the contract.
	*/
	function withdraw() public onlyOwner
	{
		uint256 balance = address(this).balance;
		require(balance > 0, "Balance is 0");
		payable(msg.sender).transfer(balance);
	}
}