// File: contracts/LBRLedger.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.9;

import './ERC721Enum.sol';
import '@openzeppelin/contracts/security/ReentrancyGuard.sol';
import './PaymentSplitter.sol';
import '@openzeppelin/contracts/utils/Address.sol';
import '@openzeppelin/contracts/utils/Strings.sol';
import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/utils/Counters.sol';
import '../interfaces/ILBRLedger.sol';

/**
 * @title LBR Ledger minting contract
 * @author Maxwell J. Rux
 */
contract LBRLedger is
  ERC721Enum,
  Ownable,
  ReentrancyGuard,
  PaymentSplitter,
  ILBRLedger
{
  using Counters for Counters.Counter;
  using Strings for uint256;

  string private _uri;
  string private _contractURI;
  uint256 private _price = 0.08 ether;
  uint256 private constant MAX_SUPPLY = 5000;
  uint256 private constant MAX_MULTIMINT = 25;
  uint256 private constant MAX_RESERVED_SUPPLY = 250;

  // number of NFTs in reserve that have already been minted
  Counters.Counter private _reserved;

  bool _status = false;

  constructor(
    string memory __uri,
    address[] memory payees,
    uint256[] memory shares,
    string memory _name,
    string memory _symbol
  ) ERC721M(_name, _symbol) PaymentSplitter(payees, shares) {
    _uri = __uri;
  }

  /**
   * @dev Mint an LBR Ledger NFT
   * @param numMints Number of mints
   */
  function mint(uint256 numMints) external payable override nonReentrant {
    require(_status, 'LBRLedger: Sale is paused');
    require(
      msg.value >= price() * numMints,
      'LBRLedger: Not enough ether sent'
    );
    require(
      totalSupply() + numMints <= MAX_SUPPLY,
      'LBRLedger: New mint exceeds maximum supply'
    );
    require(
      totalSupply() + numMints <=
        MAX_SUPPLY - MAX_RESERVED_SUPPLY + _reserved.current(),
      'LBRLedger: New mint exceeds maximum available supply'
    );
    require(
      numMints <= MAX_MULTIMINT,
      'LBRLedger: Exceeds max mints per transaction'
    );

    uint256 tokenIndex = totalSupply();
    for (uint256 i = 0; i < numMints; ++i) {
      _safeMint(msg.sender, tokenIndex + i);
    }
    delete tokenIndex;
  }

  /**
   * @dev Mints reserved NFTs to an address other than the sender. Sender must be owner
   * @param numMints Number of mints
   * @param recipient Recipient of new mints
   */
  function mintReservedToAddress(uint256 numMints, address recipient)
    external
    onlyOwner
  {
    require(
      totalSupply() + numMints <= MAX_SUPPLY,
      'LBRLedger: New mint exceeds maximum supply'
    );
    require(
      _reserved.current() + numMints <= MAX_RESERVED_SUPPLY,
      'LBRLedger: New mint exceeds reserve supply'
    );
    uint256 tokenIndex = totalSupply();
    for (uint256 i = 0; i < numMints; ++i) {
      _reserved.increment();
      _safeMint(recipient, tokenIndex + i);
    }
    delete tokenIndex;
  }

  /**
   * @dev Mints reserved NFTs to the sender. Sender must be owner
   * @param numMints Number of mints
   */
  function mintReserved(uint256 numMints) external onlyOwner {
    require(
      totalSupply() + numMints <= MAX_SUPPLY,
      'LBRLedger: New mint exceeds maximum supply'
    );
    require(
      _reserved.current() + numMints <= MAX_RESERVED_SUPPLY,
      'LBRLedger: New mint exceeds reserve supply'
    );
    uint256 tokenIndex = totalSupply();
    for (uint256 i = 0; i < numMints; ++i) {
      _reserved.increment();
      _safeMint(msg.sender, tokenIndex + i);
    }
    delete tokenIndex;
  }

  /**
   * @dev Sets base uri used for tokenURI. Sender must be owner
   * @param __uri The new uri to set base uri to
   */
  function setBaseURI(string memory __uri) external onlyOwner {
    _uri = __uri;
  }

  /**
   * @dev Sets price per mint. Sender must be owner
   * @param __price New price
   */
  function setPrice(uint256 __price) external onlyOwner {
    _price = __price;
  }

  /**
   * @dev Changes sale state to opposite of what it was previously. Sender must be owner
   */
  function flipSaleState() external onlyOwner {
    _status = !_status;
  }

  function setContractURI(string memory __contractURI) external onlyOwner {
    _contractURI = __contractURI;
  }

  function contractURI() public view override returns (string memory) {
    return _contractURI;
  }

  function price() public view override returns (uint256) {
    return _price;
  }

  function reserved() public view override returns (uint256) {
    return _reserved.current();
  }

  function baseURI() public view override returns (string memory) {
    return _uri;
  }

  function _baseURI() internal view virtual override returns (string memory) {
    return _uri;
  }
}

// File: contracts/ERC721Enum.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/ERC721Enumerable.sol)

pragma solidity ^0.8.0;

import './ERC721M.sol';
import '@openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol';

/**
 * @dev This implements an optional extension of {ERC721} defined in the EIP that adds
 * enumerability of all the token ids in the contract as well as all token ids owned by each
 * account.
 */
abstract contract ERC721Enum is ERC721M, IERC721Enumerable {
  function supportsInterface(bytes4 interfaceId)
    public
    view
    virtual
    override(IERC165, ERC721M)
    returns (bool)
  {
    return
      interfaceId == type(IERC721Enumerable).interfaceId ||
      super.supportsInterface(interfaceId);
  }

  /**
   * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
   */
  function tokenOfOwnerByIndex(address owner, uint256 index)
    public
    view
    virtual
    override
    returns (uint256)
  {
    require(
      index < ERC721M.balanceOf(owner),
      'ERC721Enum: owner index out of bounds'
    );
    uint256 counter = 0;
    for (uint256 i = 0; i < _owners.length; ++i) {
      if (owner == _owners[i]) {
        if (counter == index) {
          return i;
        } else {
          ++counter;
        }
      }
    }
    require(false, 'ERC721Enum: owner index out of bounds');
  }

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

  /**
   * @dev See {IERC721Enumerable-tokenByIndex}.
   */
  function tokenByIndex(uint256 index)
    public
    view
    virtual
    override
    returns (uint256)
  {
    require(_exists(index), 'ERC721Enumerable: global index out of bounds');
    return index;
  }

  function tokensOfOwner(address owner) public view returns (uint256[] memory) {
    require(
      ERC721M.balanceOf(owner) > 0,
      'ERC721Enum: owner index out of bounds'
    );
    uint256 b = balanceOf(owner);
    uint256[] memory ids = new uint256[](b);
    for (uint256 i = 0; i < b; ++i) {
      ids[i] = tokenOfOwnerByIndex(owner, i);
    }
    return ids;
  }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: contracts/PaymentSplitter.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import '@openzeppelin/contracts/utils/Address.sol';
import '@openzeppelin/contracts/utils/Context.sol';
import '@openzeppelin/contracts/utils/math/SafeMath.sol';

/**
 * @title PaymentSplitter
 * @dev This contract allows to split Ether payments among a group of accounts. The sender does not need to be aware
 * that the Ether will be split in this way, since it is handled transparently by the contract.
 *
 * The split can be in equal parts or in any other arbitrary proportion. The way this is specified is by assigning each
 * account to a number of shares. Of all the Ether that this contract receives, each account will then be able to claim
 * an amount proportional to the percentage of total shares they were assigned.
 *
 * `PaymentSplitter` follows a _pull payment_ model. This means that payments are not automatically forwarded to the
 * accounts but kept in this contract, and the actual transfer is triggered as a separate step by calling the {release}
 * function.
 */
contract PaymentSplitter is Context {
  event PayeeAdded(address account, uint256 shares);
  event PaymentReleased(address to, uint256 amount);
  event PaymentReceived(address from, uint256 amount);

  uint256 private _totalShares;
  uint256 private _totalReleased;

  mapping(address => uint256) private _shares;
  mapping(address => uint256) private _released;
  address[] private _payees;

  /**
   * @dev Creates an instance of `PaymentSplitter` where each account in `payees` is assigned the number of shares at
   * the matching position in the `shares` array.
   *
   * All addresses in `payees` must be non-zero. Both arrays must have the same non-zero length, and there must be no
   * duplicates in `payees`.
   */
  constructor(address[] memory payees, uint256[] memory shares_) payable {
    require(
      payees.length == shares_.length,
      'PaymentSplitter: payees and shares length mismatch'
    );
    require(payees.length > 0, 'PaymentSplitter: no payees');

    for (uint256 i = 0; i < payees.length; i++) {
      _addPayee(payees[i], shares_[i]);
    }
  }

  /**
   * @dev The Ether received will be logged with {PaymentReceived} events. Note that these events are not fully
   * reliable: it's possible for a contract to receive Ether without triggering this function. This only affects the
   * reliability of the events, and not the actual splitting of Ether.
   *
   * To learn more about this see the Solidity documentation for
   * https://solidity.readthedocs.io/en/latest/contracts.html#fallback-function[fallback
   * functions].
   */
  receive() external payable virtual {
    emit PaymentReceived(_msgSender(), msg.value);
  }

  /**
   * @dev Getter for the total shares held by payees.
   */
  function totalShares() public view returns (uint256) {
    return _totalShares;
  }

  /**
   * @dev Getter for the total amount of Ether already released.
   */
  function totalReleased() public view returns (uint256) {
    return _totalReleased;
  }

  /**
   * @dev Getter for the amount of shares held by an account.
   */
  function shares(address account) public view returns (uint256) {
    return _shares[account];
  }

  /**
   * @dev Getter for the amount of Ether already released to a payee.
   */
  function released(address account) public view returns (uint256) {
    return _released[account];
  }

  /**
   * @dev Getter for the address of the payee number `index`.
   */
  function payee(uint256 index) public view returns (address) {
    return _payees[index];
  }

  /**
   * @dev Triggers a transfer to `account` of the amount of Ether they are owed, according to their percentage of the
   * total shares and their previous withdrawals.
   */
  function release(address payable account) public virtual {
    require(_shares[account] > 0, 'PaymentSplitter: account has no shares');

    uint256 totalReceived = address(this).balance + _totalReleased;
    uint256 payment = (totalReceived * _shares[account]) /
      _totalShares -
      _released[account];

    require(payment != 0, 'PaymentSplitter: account is not due payment');

    _released[account] = _released[account] + payment;
    _totalReleased = _totalReleased + payment;

    Address.sendValue(account, payment);
    emit PaymentReleased(account, payment);
  }

  /**
   * @dev Add a new payee to the contract.
   * @param account The address of the payee to add.
   * @param shares_ The number of shares owned by the payee.
   */
  function _addPayee(address account, uint256 shares_) private {
    require(
      account != address(0),
      'PaymentSplitter: account is the zero address'
    );
    require(shares_ > 0, 'PaymentSplitter: shares are 0');
    require(
      _shares[account] == 0,
      'PaymentSplitter: account already has shares'
    );

    _payees.push(account);
    _shares[account] = shares_;
    _totalShares = _totalShares + shares_;
    emit PayeeAdded(account, shares_);
  }
}

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



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

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

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

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

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

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

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

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



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

pragma solidity ^0.8.0;

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

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

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

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

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

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



// SPDX-License-Identifier: MIT
// 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: interfaces/ILBRLedger.sol



// SPDX-License-Identifier: MIT
// Author: LBR Ledger
// Developed by Max J. Rux
// Dev GitHub: @TheBigMort

pragma solidity ^0.8.9;

interface ILBRLedger {
  function mint(uint256 numMints) external payable;

  function contractURI() external view returns (string memory);

  function price() external view returns (uint256);

  function reserved() external view returns (uint256);

  function baseURI() external view returns (string memory);
}

// File: contracts/ERC721M.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;

import '@openzeppelin/contracts/token/ERC721/IERC721.sol';
import '@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol';
import '@openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol';
import '@openzeppelin/contracts/utils/Address.sol';
import '@openzeppelin/contracts/utils/Context.sol';
import '@openzeppelin/contracts/utils/Strings.sol';
import '@openzeppelin/contracts/utils/introspection/ERC165.sol';

/**
 * @dev Modified version of the ERC721 token standard that uses arrays and iteration
 * instead of mappings for owners.
 */
contract ERC721M is Context, ERC165, IERC721, IERC721Metadata {
  using Address for address;
  using Strings for uint256;

  string private _name;
  string private _symbol;

  address[] internal _owners;

  mapping(uint256 => address) private _tokenApprovals;
  mapping(address => mapping(address => bool)) private _operatorApprovals;

  constructor(string memory name_, string memory symbol_) {
    _name = name_;
    _symbol = symbol_;
  }

  function supportsInterface(bytes4 interfaceId)
    public
    view
    virtual
    override(ERC165, IERC165)
    returns (bool)
  {
    return
      interfaceId == type(IERC721).interfaceId ||
      interfaceId == type(IERC721Metadata).interfaceId ||
      super.supportsInterface(interfaceId);
  }

  function balanceOf(address owner)
    public
    view
    virtual
    override
    returns (uint256)
  {
    require(owner != address(0), 'ERC721: balance query for the zero address');
    uint256 counter = 0;
    for (uint256 i = 0; i < _owners.length; ++i) {
      if (_owners[i] == owner) {
        ++counter;
      }
    }
    return counter;
  }

  function ownerOf(uint256 tokenId)
    public
    view
    virtual
    override
    returns (address)
  {
    require(_exists(tokenId), 'ERC721: owner query for nonexistent token');
    return _owners[tokenId];
  }

  function name() public view virtual override returns (string memory) {
    return _name;
  }

  function symbol() public view virtual override returns (string memory) {
    return _symbol;
  }

  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()))
        : '';
  }

  function _baseURI() internal view virtual returns (string memory) {
    return '';
  }

  function approve(address to, uint256 tokenId) public virtual override {
    address owner = ERC721M.ownerOf(tokenId);
    require(to != owner, 'ERC721: approval to current owner');

    require(
      _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
      'ERC721: approve caller is not owner nor approved for all'
    );

    _approve(to, tokenId);
  }

  function getApproved(uint256 tokenId)
    public
    view
    virtual
    override
    returns (address)
  {
    require(_exists(tokenId), 'ERC721: approved query for nonexistent token');

    return _tokenApprovals[tokenId];
  }

  function setApprovalForAll(address operator, bool approved)
    public
    virtual
    override
  {
    _setApprovalForAll(_msgSender(), operator, approved);
  }

  function isApprovedForAll(address owner, address operator)
    public
    view
    virtual
    override
    returns (bool)
  {
    return _operatorApprovals[owner][operator];
  }

  function transferFrom(
    address from,
    address to,
    uint256 tokenId
  ) public virtual override {
    require(
      _isApprovedOrOwner(_msgSender(), tokenId),
      'ERC721: transfer caller is not owner nor approved'
    );

    _transfer(from, to, tokenId);
  }

  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId
  ) public virtual override {
    safeTransferFrom(from, to, tokenId, '');
  }

  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId,
    bytes memory _data
  ) public virtual override {
    require(
      _isApprovedOrOwner(_msgSender(), tokenId),
      'ERC721: transfer caller is not owner nor approved'
    );
    _safeTransfer(from, to, tokenId, _data);
  }

  function _safeTransfer(
    address from,
    address to,
    uint256 tokenId,
    bytes memory _data
  ) internal virtual {
    _transfer(from, to, tokenId);
    require(
      _checkOnERC721Received(from, to, tokenId, _data),
      'ERC721: transfer to non ERC721Receiver implementer'
    );
  }

  function _exists(uint256 tokenId) internal view virtual returns (bool) {
    return tokenId >= 0 && tokenId < _owners.length;
  }

  function _isApprovedOrOwner(address spender, uint256 tokenId)
    internal
    view
    virtual
    returns (bool)
  {
    require(_exists(tokenId), 'ERC721: operator query for nonexistent token');
    address owner = ERC721M.ownerOf(tokenId);
    return (spender == owner ||
      getApproved(tokenId) == spender ||
      isApprovedForAll(owner, spender));
  }

  function _safeMint(address to, uint256 tokenId) internal virtual {
    _safeMint(to, tokenId, '');
  }

  function _safeMint(
    address to,
    uint256 tokenId,
    bytes memory _data
  ) internal virtual {
    _mint(to, tokenId);
    require(
      _checkOnERC721Received(address(0), to, tokenId, _data),
      'ERC721: transfer to non ERC721Receiver implementer'
    );
  }

  function _mint(address to, uint256 tokenId) internal virtual {
    require(to != address(0), 'ERC721: mint to the zero address');
    require(!_exists(tokenId), 'ERC721: token already minted');

    _beforeTokenTransfer(address(0), to, tokenId);

    _owners.push(to);

    emit Transfer(address(0), to, tokenId);

    _afterTokenTransfer(address(0), to, tokenId);
  }

  function _burn(uint256 tokenId) internal virtual {
    address owner = ERC721M.ownerOf(tokenId);

    _beforeTokenTransfer(owner, address(0), tokenId);

    _approve(address(0), tokenId);

    delete _owners[tokenId];

    emit Transfer(owner, address(0), tokenId);

    _afterTokenTransfer(owner, address(0), tokenId);
  }

  function _transfer(
    address from,
    address to,
    uint256 tokenId
  ) internal virtual {
    require(
      ERC721M.ownerOf(tokenId) == from,
      'ERC721: transfer from incorrect owner'
    );
    require(to != address(0), 'ERC721: transfer to the zero address');

    _beforeTokenTransfer(from, to, tokenId);

    // Clear approvals from the previous owner
    _approve(address(0), tokenId);

    _owners[tokenId] = to;

    emit Transfer(from, to, tokenId);

    _afterTokenTransfer(from, to, tokenId);
  }

  function _approve(address to, uint256 tokenId) internal virtual {
    _tokenApprovals[tokenId] = to;
    emit Approval(ERC721M.ownerOf(tokenId), to, tokenId);
  }

  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);
  }

  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 {
          assembly {
            revert(add(32, reason), mload(reason))
          }
        }
      }
    } else {
      return true;
    }
  }

  function _beforeTokenTransfer(
    address from,
    address to,
    uint256 tokenId
  ) internal virtual {}

  function _afterTokenTransfer(
    address from,
    address to,
    uint256 tokenId
  ) internal virtual {}
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/extensions/IERC721Enumerable.sol)

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Enumerable is IERC721 {
    /**
     * @dev Returns the total amount of tokens stored by the contract.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
     * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256);

    /**
     * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
     * Use along with {totalSupply} to enumerate all tokens.
     */
    function tokenByIndex(uint256 index) external view returns (uint256);
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

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

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

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

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

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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 `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @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/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: @openzeppelin/contracts/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @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/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT
// 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/math/SafeMath.sol



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

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @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;
        }
    }
}