// SPDX-License-Identifier: MIT

// OpenZeppelin Contracts (last updated v4.7.0) (utils/cryptography/MerkleProof.sol)

pragma solidity ^0.8.0;

/**
 * @dev These functions deal with verification of Merkle Tree 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.
 *
 * WARNING: You should avoid using leaf values that are 64 bytes long prior to
 * hashing, or use a hash function other than keccak256 for hashing leaves.
 * This is because the concatenation of a sorted pair of internal nodes in
 * the merkle tree could be reinterpreted as a leaf value.
 */
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 Calldata version of {verify}
 *
 * _Available since v4.7._
 */
 function verifyCalldata(
 bytes32[] calldata proof,
 bytes32 root,
 bytes32 leaf
 ) internal pure returns (bool) {
 return processProofCalldata(proof, leaf) == root;
 }

 /**
 * @dev Returns the rebuilt hash obtained by traversing a Merkle 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++) {
 computedHash = _hashPair(computedHash, proof[i]);
 }
 return computedHash;
 }

 /**
 * @dev Calldata version of {processProof}
 *
 * _Available since v4.7._
 */
 function processProofCalldata(bytes32[] calldata proof, bytes32 leaf) internal pure returns (bytes32) {
 bytes32 computedHash = leaf;
 for (uint256 i = 0; i < proof.length; i++) {
 computedHash = _hashPair(computedHash, proof[i]);
 }
 return computedHash;
 }

 /**
 * @dev Returns true if the `leaves` can be proved to be a part of a Merkle tree defined by
 * `root`, according to `proof` and `proofFlags` as described in {processMultiProof}.
 *
 * _Available since v4.7._
 */
 function multiProofVerify(
 bytes32[] memory proof,
 bool[] memory proofFlags,
 bytes32 root,
 bytes32[] memory leaves
 ) internal pure returns (bool) {
 return processMultiProof(proof, proofFlags, leaves) == root;
 }

 /**
 * @dev Calldata version of {multiProofVerify}
 *
 * _Available since v4.7._
 */
 function multiProofVerifyCalldata(
 bytes32[] calldata proof,
 bool[] calldata proofFlags,
 bytes32 root,
 bytes32[] memory leaves
 ) internal pure returns (bool) {
 return processMultiProofCalldata(proof, proofFlags, leaves) == root;
 }

 /**
 * @dev Returns the root of a tree reconstructed from `leaves` and the sibling nodes in `proof`,
 * consuming from one or the other at each step according to the instructions given by
 * `proofFlags`.
 *
 * _Available since v4.7._
 */
 function processMultiProof(
 bytes32[] memory proof,
 bool[] memory proofFlags,
 bytes32[] memory leaves
 ) internal pure returns (bytes32 merkleRoot) {
 // This function rebuild the root hash by traversing the tree up from the leaves. The root is rebuilt by
 // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
 // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
 // the merkle tree.
 uint256 leavesLen = leaves.length;
 uint256 totalHashes = proofFlags.length;

 // Check proof validity.
 require(leavesLen + proof.length - 1 == totalHashes, "MerkleProof: invalid multiproof");

 // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
 // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
 bytes32[] memory hashes = new bytes32[](totalHashes);
 uint256 leafPos = 0;
 uint256 hashPos = 0;
 uint256 proofPos = 0;
 // At each step, we compute the next hash using two values:
 // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
 // get the next hash.
 // - depending on the flag, either another value for the "main queue" (merging branches) or an element from the
 // `proof` array.
 for (uint256 i = 0; i < totalHashes; i++) {
 bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
 bytes32 b = proofFlags[i] ? leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++] : proof[proofPos++];
 hashes[i] = _hashPair(a, b);
 }

 if (totalHashes > 0) {
 return hashes[totalHashes - 1];
 } else if (leavesLen > 0) {
 return leaves[0];
 } else {
 return proof[0];
 }
 }

 /**
 * @dev Calldata version of {processMultiProof}
 *
 * _Available since v4.7._
 */
 function processMultiProofCalldata(
 bytes32[] calldata proof,
 bool[] calldata proofFlags,
 bytes32[] memory leaves
 ) internal pure returns (bytes32 merkleRoot) {
 // This function rebuild the root hash by traversing the tree up from the leaves. The root is rebuilt by
 // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
 // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
 // the merkle tree.
 uint256 leavesLen = leaves.length;
 uint256 totalHashes = proofFlags.length;

 // Check proof validity.
 require(leavesLen + proof.length - 1 == totalHashes, "MerkleProof: invalid multiproof");

 // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
 // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
 bytes32[] memory hashes = new bytes32[](totalHashes);
 uint256 leafPos = 0;
 uint256 hashPos = 0;
 uint256 proofPos = 0;
 // At each step, we compute the next hash using two values:
 // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
 // get the next hash.
 // - depending on the flag, either another value for the "main queue" (merging branches) or an element from the
 // `proof` array.
 for (uint256 i = 0; i < totalHashes; i++) {
 bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
 bytes32 b = proofFlags[i] ? leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++] : proof[proofPos++];
 hashes[i] = _hashPair(a, b);
 }

 if (totalHashes > 0) {
 return hashes[totalHashes - 1];
 } else if (leavesLen > 0) {
 return leaves[0];
 } else {
 return proof[0];
 }
 }

 function _hashPair(bytes32 a, bytes32 b) private pure returns (bytes32) {
 return a < b ? _efficientHash(a, b) : _efficientHash(b, a);
 }

 function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
 /// @solidity memory-safe-assembly
 assembly {
 mstore(0x00, a)
 mstore(0x20, b)
 value := keccak256(0x00, 0x40)
 }
 }
}

// File: @openzeppelin/contracts/utils/Counters.sol


// OpenZeppelin Contracts v4.4.1 (utils/Counters.sol)

pragma solidity ^0.8.0;

/**
 * @title Counters
 * @author Matt Condon (@shrugs)
 * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
 * of elements in a mapping, issuing ERC721 ids, or counting request ids.
 *
 * Include with `using Counters for Counters.Counter;`
 */
library Counters {
 struct Counter {
 // This variable should never be directly accessed by users of the library: interactions must be restricted to
 // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
 // this feature: see https://github.com/ethereum/solidity/issues/4637
 uint256 _value; // default: 0
 }

 function current(Counter storage counter) internal view returns (uint256) {
 return counter._value;
 }

 function increment(Counter storage counter) internal {
 unchecked {
 counter._value += 1;
 }
 }

 function decrement(Counter storage counter) internal {
 uint256 value = counter._value;
 require(value > 0, "Counter: decrement overflow");
 unchecked {
 counter._value = value - 1;
 }
 }

 function reset(Counter storage counter) internal {
 counter._value = 0;
 }
}

// File: @openzeppelin/contracts/utils/Strings.sol


// OpenZeppelin Contracts (last updated v4.7.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
 bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
 uint8 private constant _ADDRESS_LENGTH = 20;

 /**
 * @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 Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
 */
 function toHexString(address addr) internal pure returns (string memory) {
 return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
 }
}

// File: @openzeppelin/contracts/utils/Context.sol


// 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: @openzeppelin/contracts/access/Ownable.sol


// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;


/**
 * @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 Throws if called by any account other than the owner.
 */
 modifier onlyOwner() {
 _checkOwner();
 _;
 }

 /**
 * @dev Returns the address of the current owner.
 */
 function owner() public view virtual returns (address) {
 return _owner;
 }

 /**
 * @dev Throws if the sender is not the owner.
 */
 function _checkOwner() internal view virtual {
 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/Address.sol


// OpenZeppelin Contracts (last updated v4.7.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
 /**
 * @dev Returns true if `account` is a contract.
 *
 * [IMPORTANT]
 * ====
 * It is unsafe to assume that an address for which this function returns
 * false is an externally-owned account (EOA) and not a contract.
 *
 * Among others, `isContract` will return false for the following
 * types of addresses:
 *
 * - an externally-owned account
 * - a contract in construction
 * - an address where a contract will be created
 * - an address where a contract lived, but was destroyed
 * ====
 *
 * [IMPORTANT]
 * ====
 * You shouldn't rely on `isContract` to protect against flash loan attacks!
 *
 * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
 * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
 * constructor.
 * ====
 */
 function isContract(address account) internal view returns (bool) {
 // This method relies on extcodesize/address.code.length, which returns 0
 // for contracts in construction, since the code is only stored at the end
 // of the constructor execution.

 return account.code.length > 0;
 }

 /**
 * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
 * `recipient`, forwarding all available gas and reverting on errors.
 *
 * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
 * of certain opcodes, possibly making contracts go over the 2300 gas limit
 * imposed by `transfer`, making them unable to receive funds via
 * `transfer`. {sendValue} removes this limitation.
 *
 * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
 *
 * IMPORTANT: because control is transferred to `recipient`, care must be
 * taken to not create reentrancy vulnerabilities. Consider using
 * {ReentrancyGuard} or the
 * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
 */
 function sendValue(address payable recipient, uint256 amount) internal {
 require(address(this).balance >= amount, "Address: insufficient balance");

 (bool success, ) = recipient.call{value: amount}("");
 require(success, "Address: unable to send value, recipient may have reverted");
 }

 /**
 * @dev Performs a Solidity function call using a low level `call`. A
 * plain `call` is an unsafe replacement for a function call: use this
 * function instead.
 *
 * If `target` reverts with a revert reason, it is bubbled up by this
 * function (like regular Solidity function calls).
 *
 * Returns the raw returned data. To convert to the expected return value,
 * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
 *
 * Requirements:
 *
 * - `target` must be a contract.
 * - calling `target` with `data` must not revert.
 *
 * _Available since v3.1._
 */
 function functionCall(address target, bytes memory data) internal returns (bytes memory) {
 return functionCall(target, data, "Address: low-level call failed");
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
 * `errorMessage` as a fallback revert reason when `target` reverts.
 *
 * _Available since v3.1._
 */
 function functionCall(
 address target,
 bytes memory data,
 string memory errorMessage
 ) internal returns (bytes memory) {
 return functionCallWithValue(target, data, 0, errorMessage);
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
 * but also transferring `value` wei to `target`.
 *
 * Requirements:
 *
 * - the calling contract must have an ETH balance of at least `value`.
 * - the called Solidity function must be `payable`.
 *
 * _Available since v3.1._
 */
 function functionCallWithValue(
 address target,
 bytes memory data,
 uint256 value
 ) internal returns (bytes memory) {
 return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
 }

 /**
 * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
 * with `errorMessage` as a fallback revert reason when `target` reverts.
 *
 * _Available since v3.1._
 */
 function functionCallWithValue(
 address target,
 bytes memory data,
 uint256 value,
 string memory errorMessage
 ) internal returns (bytes memory) {
 require(address(this).balance >= value, "Address: insufficient balance for call");
 require(isContract(target), "Address: call to non-contract");

 (bool success, bytes memory returndata) = target.call{value: value}(data);
 return verifyCallResult(success, returndata, errorMessage);
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
 * but performing a static call.
 *
 * _Available since v3.3._
 */
 function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
 return functionStaticCall(target, data, "Address: low-level static call failed");
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
 * but performing a static call.
 *
 * _Available since v3.3._
 */
 function functionStaticCall(
 address target,
 bytes memory data,
 string memory errorMessage
 ) internal view returns (bytes memory) {
 require(isContract(target), "Address: static call to non-contract");

 (bool success, bytes memory returndata) = target.staticcall(data);
 return verifyCallResult(success, returndata, errorMessage);
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
 * but performing a delegate call.
 *
 * _Available since v3.4._
 */
 function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
 return functionDelegateCall(target, data, "Address: low-level delegate call failed");
 }

 /**
 * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
 * but performing a delegate call.
 *
 * _Available since v3.4._
 */
 function functionDelegateCall(
 address target,
 bytes memory data,
 string memory errorMessage
 ) internal returns (bytes memory) {
 require(isContract(target), "Address: delegate call to non-contract");

 (bool success, bytes memory returndata) = target.delegatecall(data);
 return verifyCallResult(success, returndata, errorMessage);
 }

 /**
 * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
 * revert reason using the provided one.
 *
 * _Available since v4.3._
 */
 function verifyCallResult(
 bool success,
 bytes memory returndata,
 string memory errorMessage
 ) internal pure returns (bytes memory) {
 if (success) {
 return returndata;
 } else {
 // Look for revert reason and bubble it up if present
 if (returndata.length > 0) {
 // The easiest way to bubble the revert reason is using memory via assembly
 /// @solidity memory-safe-assembly
 assembly {
 let returndata_size := mload(returndata)
 revert(add(32, returndata), returndata_size)
 }
 } else {
 revert(errorMessage);
 }
 }
 }
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol


// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
 /**
 * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
 * by `operator` from `from`, this function is called.
 *
 * It must return its Solidity selector to confirm the token transfer.
 * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
 *
 * The selector can be obtained in Solidity with `IERC721Receiver.onERC721Received.selector`.
 */
 function onERC721Received(
 address operator,
 address from,
 uint256 tokenId,
 bytes calldata data
 ) external returns (bytes4);
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol


// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
 /**
 * @dev Returns true if this contract implements the interface defined by
 * `interfaceId`. See the corresponding
 * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
 * to learn more about how these ids are created.
 *
 * This function call must use less than 30 000 gas.
 */
 function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts/utils/introspection/ERC165.sol


// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;


/**
 * @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;
 }
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol


// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;


/**
 * @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 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);
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol


// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.0;


/**
 * @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/token/ERC721/ERC721.sol

// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;



/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
 using Address for address;
 using Strings for uint256;

 // 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;

 // Mapping from token ID to kadena address
 mapping(uint256 => string) private _kadenaAddresses;

 // Mapping from token ID to the amount of KDA NFTs each ETH NFT represents
 mapping(uint256 => uint256) private _amountMinted;

 /**
 * @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), "ERC721: address zero is not a valid owner");
 return _balances[owner];
 }

 /**
 * @dev See {IERC721-ownerOf}.
 */
 function ownerOf(uint256 tokenId) public view virtual override returns (address) {
 address owner = _owners[tokenId];
 require(owner != address(0), "ERC721: invalid token ID");
 return owner;
 }

 function kAddressOf(uint256 tokenId) public view virtual returns (string memory) {
 string memory kAddress = _kadenaAddresses[tokenId];
 return kAddress;
 }

 function amountMinted(uint256 tokenId) public view virtual returns (uint256) {
 uint256 amountMintedBy = _amountMinted[tokenId];
 return amountMintedBy;
 }

 /**
 * @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) {
 _requireMinted(tokenId);

 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 overridden 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 = ERC721.ownerOf(tokenId);
 require(to != owner, "ERC721: approval to current owner");

 require(
 _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
 "ERC721: approve caller is not token owner nor approved for all"
 );

 _approve(to, tokenId);
 }

 /**
 * @dev See {IERC721-getApproved}.
 */
 function getApproved(uint256 tokenId) public view virtual override returns (address) {
 _requireMinted(tokenId);

 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 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 _owners[tokenId] != address(0);
 }

 /**
 * @dev Returns whether `spender` is allowed to manage `tokenId`.
 *
 * Requirements:
 *
 * - `tokenId` must exist.
 */
 function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
 address owner = ERC721.ownerOf(tokenId);
 return (spender == owner || isApprovedForAll(owner, spender) || getApproved(tokenId) == 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 tokenId, string memory kadenaAddress, uint256 amountMintedBy) internal virtual {
 _safeMint(to, tokenId, "", kadenaAddress, amountMintedBy);
 }

 /**
 * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
 * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
 */
 function _safeMint(
 address to,
 uint256 tokenId,
 bytes memory data,
 string memory kadenaAddress,
 uint256 amountMintedBy
 ) internal virtual {
 _mint(to, tokenId, kadenaAddress, amountMintedBy);
 require(
 _checkOnERC721Received(address(0), to, tokenId, data),
 "ERC721: transfer to non ERC721Receiver implementer"
 );
 }

 /**
 * @dev Mints `tokenId` and transfers it to `to`.
 *
 * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
 *
 * Requirements:
 *
 * - `tokenId` must not exist.
 * - `to` cannot be the zero address.
 *
 * Emits a {Transfer} event.
 */
 function _mint(address to, uint256 tokenId, string memory kadenaAddress, uint256 amountMintedBy) internal virtual {
 require(to != address(0), "ERC721: mint to the zero address");
 require(!_exists(tokenId), "ERC721: token already minted");

 _beforeTokenTransfer(address(0), to, tokenId);

 _balances[to] += 1;
 _owners[tokenId] = to;
 _kadenaAddresses[tokenId] = kadenaAddress;
 _amountMinted[tokenId] = amountMintedBy;
 emit Transfer(address(0), to, tokenId);

 _afterTokenTransfer(address(0), to, tokenId);
 }

 /**
 * @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 = ERC721.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 Approve `to` to operate on `tokenId`
 *
 * Emits an {Approval} event.
 */
 function _approve(address to, uint256 tokenId) internal virtual {
 _tokenApprovals[tokenId] = to;
 emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
 }

 /**
 * @dev Approve `operator` to operate on all of `owner` tokens
 *
 * Emits an {ApprovalForAll} event.
 */
 function _setApprovalForAll(
 address owner,
 address operator,
 bool approved
 ) internal virtual {
 require(owner != operator, "ERC721: approve to caller");
 _operatorApprovals[owner][operator] = approved;
 emit ApprovalForAll(owner, operator, approved);
 }

 /**
 * @dev Reverts if the `tokenId` has not been minted yet.
 */
 function _requireMinted(uint256 tokenId) internal view virtual {
 require(_exists(tokenId), "ERC721: invalid token ID");
 }

 /**
 * @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("ERC721: transfer to non ERC721Receiver implementer");
 } else {
 /// @solidity memory-safe-assembly
 assembly {
 revert(add(32, reason), mload(reason))
 }
 }
 }
 } else {
 return true;
 }
 }

 /**
 * @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 {}
}

// File: contracts/LowGas.sol

pragma solidity >=0.7.0 <0.9.0;


contract KadenaMiningClub is ERC721, Ownable {
 using Strings for uint256;
 using Counters for Counters.Counter;

 Counters.Counter private kadenaSupply;
 Counters.Counter private ethSupply;
 bytes32 public root;

 string public uriPrefix = "";
 string public uriSuffix = ".json";
 string public hiddenMetadataUri;
 
 uint256 public cost = 0.202 ether;
 uint256 public maxKadenaSupply = 6740;
 uint256 public maxMintAmountPerTx = 50;

 bool public paused = true;
 bool public revealed = false;
 bool public allowListOnly = true;

 constructor() ERC721("Kadena Mining Club", "KMC") {
 setHiddenMetadataUri("ipfs://QSDFW34DD/hidden.json");
 }

 modifier mintCompliance(uint256 _mintAmount) {
 require(_mintAmount > 0 && _mintAmount <= maxMintAmountPerTx, "Invalid mint amount!");
 require(kadenaSupply.current() + _mintAmount <= maxKadenaSupply, "Max kadenaSupply exceeded!");
 _;
 }

 function totalSupply() public view returns (uint256) {
 return kadenaSupply.current();
 }

 function totalEthSupply() public view returns (uint256) {
 return ethSupply.current();
 }

 function mint(uint256 _mintAmount, string memory kadenaAddress, bytes32[] calldata proof) public payable mintCompliance(_mintAmount) {
 require(!paused, "The contract is paused!");
 require(msg.value >= cost * _mintAmount, "Insufficient funds!");
 if (allowListOnly == true) {
 require(isValid(proof, keccak256(abi.encodePacked(msg.sender))), "You are not a part of Allowlist, please wait until public sale");
 }
 _mintLoop(msg.sender, _mintAmount, kadenaAddress);
 }
 
 function mintForAddress(uint256 _mintAmount, address _receiver, string memory kadenaAddress) public mintCompliance(_mintAmount) onlyOwner {
 _mintLoop(_receiver, _mintAmount, kadenaAddress);
 }

 function isValid(bytes32[] memory proof, bytes32 leaf) public view returns (bool) {
 return MerkleProof.verify(proof, root, leaf);
 }

////////////////////////
 function crossmint(uint256 numToMint, uint256 _kAmount, address _to, string memory kadenaAddress) public payable mintCompliance(_kAmount) {
 require(!paused, "The contract is paused!");
 require(msg.value >= cost * _kAmount, "Insufficient funds!");
 require(msg.sender == 0xdAb1a1854214684acE522439684a145E62505233,
 "This function is for Crossmint only."
 );
 for (uint256 i = 0; i < _kAmount; i++) {
 kadenaSupply.increment();
 }
 ethSupply.increment();
 _safeMint(_to, ethSupply.current(), kadenaAddress, _kAmount);
 }
////////////////////////

 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 <= maxKadenaSupply) {
 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"
 );

 if (revealed == false) {
 return hiddenMetadataUri;
 }

 string memory currentBaseURI = _baseURI();
 return bytes(currentBaseURI).length > 0
 ? string(abi.encodePacked(currentBaseURI, _tokenId.toString(), uriSuffix))
 : "";
 }

 function setRevealed(bool _state) public onlyOwner {
 revealed = _state;
 }

 function setCost(uint256 _cost) public onlyOwner {
 cost = _cost;
 }

 function setMaxMintAmountPerTx(uint256 _maxMintAmountPerTx) public onlyOwner {
 maxMintAmountPerTx = _maxMintAmountPerTx;
 }

 function setHiddenMetadataUri(string memory _hiddenMetadataUri) public onlyOwner {
 hiddenMetadataUri = _hiddenMetadataUri;
 }

 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 setAllowListOnly(bool _state) public onlyOwner {
 allowListOnly = _state;
 }

 function setroot(bytes32 _newRoot) public onlyOwner {
 root = _newRoot;
 }

 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 _mintLoop(address _receiver, uint256 _mintAmount, string memory kadenaAddress) internal {
 for (uint256 i = 0; i < _mintAmount; i++) {
 kadenaSupply.increment();
 }
 ethSupply.increment();
 _safeMint(_receiver, ethSupply.current(), kadenaAddress, _mintAmount);
 }

 function _baseURI() internal view virtual override returns (string memory) {
 return uriPrefix;
 }
}