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Contract Diff Checker

Contract Name:
Dice

Contract Source Code:

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)

pragma solidity ^0.8.20;

import {Context} from "../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.
 *
 * The initial owner is set to the address provided by the deployer. 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;

    /**
     * @dev The caller account is not authorized to perform an operation.
     */
    error OwnableUnauthorizedAccount(address account);

    /**
     * @dev The owner is not a valid owner account. (eg. `address(0)`)
     */
    error OwnableInvalidOwner(address owner);

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
     */
    constructor(address initialOwner) {
        if (initialOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(initialOwner);
    }

    /**
     * @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 {
        if (owner() != _msgSender()) {
            revert OwnableUnauthorizedAccount(_msgSender());
        }
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling 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 {
        if (newOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _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);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/draft-IERC6093.sol)
pragma solidity ^0.8.20;

/**
 * @dev Standard ERC20 Errors
 * Interface of the https://eips.ethereum.org/EIPS/eip-6093[ERC-6093] custom errors for ERC20 tokens.
 */
interface IERC20Errors {
    /**
     * @dev Indicates an error related to the current `balance` of a `sender`. Used in transfers.
     * @param sender Address whose tokens are being transferred.
     * @param balance Current balance for the interacting account.
     * @param needed Minimum amount required to perform a transfer.
     */
    error ERC20InsufficientBalance(address sender, uint256 balance, uint256 needed);

    /**
     * @dev Indicates a failure with the token `sender`. Used in transfers.
     * @param sender Address whose tokens are being transferred.
     */
    error ERC20InvalidSender(address sender);

    /**
     * @dev Indicates a failure with the token `receiver`. Used in transfers.
     * @param receiver Address to which tokens are being transferred.
     */
    error ERC20InvalidReceiver(address receiver);

    /**
     * @dev Indicates a failure with the `spender`’s `allowance`. Used in transfers.
     * @param spender Address that may be allowed to operate on tokens without being their owner.
     * @param allowance Amount of tokens a `spender` is allowed to operate with.
     * @param needed Minimum amount required to perform a transfer.
     */
    error ERC20InsufficientAllowance(address spender, uint256 allowance, uint256 needed);

    /**
     * @dev Indicates a failure with the `approver` of a token to be approved. Used in approvals.
     * @param approver Address initiating an approval operation.
     */
    error ERC20InvalidApprover(address approver);

    /**
     * @dev Indicates a failure with the `spender` to be approved. Used in approvals.
     * @param spender Address that may be allowed to operate on tokens without being their owner.
     */
    error ERC20InvalidSpender(address spender);
}

/**
 * @dev Standard ERC721 Errors
 * Interface of the https://eips.ethereum.org/EIPS/eip-6093[ERC-6093] custom errors for ERC721 tokens.
 */
interface IERC721Errors {
    /**
     * @dev Indicates that an address can't be an owner. For example, `address(0)` is a forbidden owner in EIP-20.
     * Used in balance queries.
     * @param owner Address of the current owner of a token.
     */
    error ERC721InvalidOwner(address owner);

    /**
     * @dev Indicates a `tokenId` whose `owner` is the zero address.
     * @param tokenId Identifier number of a token.
     */
    error ERC721NonexistentToken(uint256 tokenId);

    /**
     * @dev Indicates an error related to the ownership over a particular token. Used in transfers.
     * @param sender Address whose tokens are being transferred.
     * @param tokenId Identifier number of a token.
     * @param owner Address of the current owner of a token.
     */
    error ERC721IncorrectOwner(address sender, uint256 tokenId, address owner);

    /**
     * @dev Indicates a failure with the token `sender`. Used in transfers.
     * @param sender Address whose tokens are being transferred.
     */
    error ERC721InvalidSender(address sender);

    /**
     * @dev Indicates a failure with the token `receiver`. Used in transfers.
     * @param receiver Address to which tokens are being transferred.
     */
    error ERC721InvalidReceiver(address receiver);

    /**
     * @dev Indicates a failure with the `operator`’s approval. Used in transfers.
     * @param operator Address that may be allowed to operate on tokens without being their owner.
     * @param tokenId Identifier number of a token.
     */
    error ERC721InsufficientApproval(address operator, uint256 tokenId);

    /**
     * @dev Indicates a failure with the `approver` of a token to be approved. Used in approvals.
     * @param approver Address initiating an approval operation.
     */
    error ERC721InvalidApprover(address approver);

    /**
     * @dev Indicates a failure with the `operator` to be approved. Used in approvals.
     * @param operator Address that may be allowed to operate on tokens without being their owner.
     */
    error ERC721InvalidOperator(address operator);
}

/**
 * @dev Standard ERC1155 Errors
 * Interface of the https://eips.ethereum.org/EIPS/eip-6093[ERC-6093] custom errors for ERC1155 tokens.
 */
interface IERC1155Errors {
    /**
     * @dev Indicates an error related to the current `balance` of a `sender`. Used in transfers.
     * @param sender Address whose tokens are being transferred.
     * @param balance Current balance for the interacting account.
     * @param needed Minimum amount required to perform a transfer.
     * @param tokenId Identifier number of a token.
     */
    error ERC1155InsufficientBalance(address sender, uint256 balance, uint256 needed, uint256 tokenId);

    /**
     * @dev Indicates a failure with the token `sender`. Used in transfers.
     * @param sender Address whose tokens are being transferred.
     */
    error ERC1155InvalidSender(address sender);

    /**
     * @dev Indicates a failure with the token `receiver`. Used in transfers.
     * @param receiver Address to which tokens are being transferred.
     */
    error ERC1155InvalidReceiver(address receiver);

    /**
     * @dev Indicates a failure with the `operator`’s approval. Used in transfers.
     * @param operator Address that may be allowed to operate on tokens without being their owner.
     * @param owner Address of the current owner of a token.
     */
    error ERC1155MissingApprovalForAll(address operator, address owner);

    /**
     * @dev Indicates a failure with the `approver` of a token to be approved. Used in approvals.
     * @param approver Address initiating an approval operation.
     */
    error ERC1155InvalidApprover(address approver);

    /**
     * @dev Indicates a failure with the `operator` to be approved. Used in approvals.
     * @param operator Address that may be allowed to operate on tokens without being their owner.
     */
    error ERC1155InvalidOperator(address operator);

    /**
     * @dev Indicates an array length mismatch between ids and values in a safeBatchTransferFrom operation.
     * Used in batch transfers.
     * @param idsLength Length of the array of token identifiers
     * @param valuesLength Length of the array of token amounts
     */
    error ERC1155InvalidArrayLength(uint256 idsLength, uint256 valuesLength);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.20;

import {IERC721} from "./IERC721.sol";
import {IERC721Receiver} from "./IERC721Receiver.sol";
import {IERC721Metadata} from "./extensions/IERC721Metadata.sol";
import {Context} from "../../utils/Context.sol";
import {Strings} from "../../utils/Strings.sol";
import {IERC165, ERC165} from "../../utils/introspection/ERC165.sol";
import {IERC721Errors} from "../../interfaces/draft-IERC6093.sol";

/**
 * @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}.
 */
abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Errors {
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    mapping(uint256 tokenId => address) private _owners;

    mapping(address owner => uint256) private _balances;

    mapping(uint256 tokenId => address) private _tokenApprovals;

    mapping(address owner => mapping(address operator => bool)) private _operatorApprovals;

    /**
     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

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

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual returns (uint256) {
        if (owner == address(0)) {
            revert ERC721InvalidOwner(address(0));
        }
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual returns (address) {
        return _requireOwned(tokenId);
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual returns (string memory) {
        _requireOwned(tokenId);

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string.concat(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 {
        _approve(to, tokenId, _msgSender());
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual returns (address) {
        _requireOwned(tokenId);

        return _getApproved(tokenId);
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual {
        _setApprovalForAll(_msgSender(), operator, approved);
    }

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

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(address from, address to, uint256 tokenId) public virtual {
        if (to == address(0)) {
            revert ERC721InvalidReceiver(address(0));
        }
        // Setting an "auth" arguments enables the `_isAuthorized` check which verifies that the token exists
        // (from != 0). Therefore, it is not needed to verify that the return value is not 0 here.
        address previousOwner = _update(to, tokenId, _msgSender());
        if (previousOwner != from) {
            revert ERC721IncorrectOwner(from, tokenId, previousOwner);
        }
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) public {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory data) public virtual {
        transferFrom(from, to, tokenId);
        _checkOnERC721Received(from, to, tokenId, data);
    }

    /**
     * @dev Returns the owner of the `tokenId`. Does NOT revert if token doesn't exist
     *
     * IMPORTANT: Any overrides to this function that add ownership of tokens not tracked by the
     * core ERC721 logic MUST be matched with the use of {_increaseBalance} to keep balances
     * consistent with ownership. The invariant to preserve is that for any address `a` the value returned by
     * `balanceOf(a)` must be equal to the number of tokens such that `_ownerOf(tokenId)` is `a`.
     */
    function _ownerOf(uint256 tokenId) internal view virtual returns (address) {
        return _owners[tokenId];
    }

    /**
     * @dev Returns the approved address for `tokenId`. Returns 0 if `tokenId` is not minted.
     */
    function _getApproved(uint256 tokenId) internal view virtual returns (address) {
        return _tokenApprovals[tokenId];
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `owner`'s tokens, or `tokenId` in
     * particular (ignoring whether it is owned by `owner`).
     *
     * WARNING: This function assumes that `owner` is the actual owner of `tokenId` and does not verify this
     * assumption.
     */
    function _isAuthorized(address owner, address spender, uint256 tokenId) internal view virtual returns (bool) {
        return
            spender != address(0) &&
            (owner == spender || isApprovedForAll(owner, spender) || _getApproved(tokenId) == spender);
    }

    /**
     * @dev Checks if `spender` can operate on `tokenId`, assuming the provided `owner` is the actual owner.
     * Reverts if `spender` does not have approval from the provided `owner` for the given token or for all its assets
     * the `spender` for the specific `tokenId`.
     *
     * WARNING: This function assumes that `owner` is the actual owner of `tokenId` and does not verify this
     * assumption.
     */
    function _checkAuthorized(address owner, address spender, uint256 tokenId) internal view virtual {
        if (!_isAuthorized(owner, spender, tokenId)) {
            if (owner == address(0)) {
                revert ERC721NonexistentToken(tokenId);
            } else {
                revert ERC721InsufficientApproval(spender, tokenId);
            }
        }
    }

    /**
     * @dev Unsafe write access to the balances, used by extensions that "mint" tokens using an {ownerOf} override.
     *
     * NOTE: the value is limited to type(uint128).max. This protect against _balance overflow. It is unrealistic that
     * a uint256 would ever overflow from increments when these increments are bounded to uint128 values.
     *
     * WARNING: Increasing an account's balance using this function tends to be paired with an override of the
     * {_ownerOf} function to resolve the ownership of the corresponding tokens so that balances and ownership
     * remain consistent with one another.
     */
    function _increaseBalance(address account, uint128 value) internal virtual {
        unchecked {
            _balances[account] += value;
        }
    }

    /**
     * @dev Transfers `tokenId` from its current owner to `to`, or alternatively mints (or burns) if the current owner
     * (or `to`) is the zero address. Returns the owner of the `tokenId` before the update.
     *
     * The `auth` argument is optional. If the value passed is non 0, then this function will check that
     * `auth` is either the owner of the token, or approved to operate on the token (by the owner).
     *
     * Emits a {Transfer} event.
     *
     * NOTE: If overriding this function in a way that tracks balances, see also {_increaseBalance}.
     */
    function _update(address to, uint256 tokenId, address auth) internal virtual returns (address) {
        address from = _ownerOf(tokenId);

        // Perform (optional) operator check
        if (auth != address(0)) {
            _checkAuthorized(from, auth, tokenId);
        }

        // Execute the update
        if (from != address(0)) {
            // Clear approval. No need to re-authorize or emit the Approval event
            _approve(address(0), tokenId, address(0), false);

            unchecked {
                _balances[from] -= 1;
            }
        }

        if (to != address(0)) {
            unchecked {
                _balances[to] += 1;
            }
        }

        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);

        return from;
    }

    /**
     * @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) internal {
        if (to == address(0)) {
            revert ERC721InvalidReceiver(address(0));
        }
        address previousOwner = _update(to, tokenId, address(0));
        if (previousOwner != address(0)) {
            revert ERC721InvalidSender(address(0));
        }
    }

    /**
     * @dev Mints `tokenId`, transfers it to `to` and checks for `to` acceptance.
     *
     * 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) internal {
        _safeMint(to, tokenId, "");
    }

    /**
     * @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) internal virtual {
        _mint(to, tokenId);
        _checkOnERC721Received(address(0), to, tokenId, data);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     * This is an internal function that does not check if the sender is authorized to operate on the token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal {
        address previousOwner = _update(address(0), tokenId, address(0));
        if (previousOwner == address(0)) {
            revert ERC721NonexistentToken(tokenId);
        }
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(address from, address to, uint256 tokenId) internal {
        if (to == address(0)) {
            revert ERC721InvalidReceiver(address(0));
        }
        address previousOwner = _update(to, tokenId, address(0));
        if (previousOwner == address(0)) {
            revert ERC721NonexistentToken(tokenId);
        } else if (previousOwner != from) {
            revert ERC721IncorrectOwner(from, tokenId, previousOwner);
        }
    }

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking that contract recipients
     * are aware of the ERC721 standard to prevent tokens from being forever locked.
     *
     * `data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is like {safeTransferFrom} in the sense that it invokes
     * {IERC721Receiver-onERC721Received} on the receiver, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `tokenId` token must exist and be owned by `from`.
     * - `to` cannot be the zero address.
     * - `from` cannot be the zero address.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(address from, address to, uint256 tokenId) internal {
        _safeTransfer(from, to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeTransfer-address-address-uint256-}[`_safeTransfer`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeTransfer(address from, address to, uint256 tokenId, bytes memory data) internal virtual {
        _transfer(from, to, tokenId);
        _checkOnERC721Received(from, to, tokenId, data);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * The `auth` argument is optional. If the value passed is non 0, then this function will check that `auth` is
     * either the owner of the token, or approved to operate on all tokens held by this owner.
     *
     * Emits an {Approval} event.
     *
     * Overrides to this logic should be done to the variant with an additional `bool emitEvent` argument.
     */
    function _approve(address to, uint256 tokenId, address auth) internal {
        _approve(to, tokenId, auth, true);
    }

    /**
     * @dev Variant of `_approve` with an optional flag to enable or disable the {Approval} event. The event is not
     * emitted in the context of transfers.
     */
    function _approve(address to, uint256 tokenId, address auth, bool emitEvent) internal virtual {
        // Avoid reading the owner unless necessary
        if (emitEvent || auth != address(0)) {
            address owner = _requireOwned(tokenId);

            // We do not use _isAuthorized because single-token approvals should not be able to call approve
            if (auth != address(0) && owner != auth && !isApprovedForAll(owner, auth)) {
                revert ERC721InvalidApprover(auth);
            }

            if (emitEvent) {
                emit Approval(owner, to, tokenId);
            }
        }

        _tokenApprovals[tokenId] = to;
    }

    /**
     * @dev Approve `operator` to operate on all of `owner` tokens
     *
     * Requirements:
     * - operator can't be the address zero.
     *
     * Emits an {ApprovalForAll} event.
     */
    function _setApprovalForAll(address owner, address operator, bool approved) internal virtual {
        if (operator == address(0)) {
            revert ERC721InvalidOperator(operator);
        }
        _operatorApprovals[owner][operator] = approved;
        emit ApprovalForAll(owner, operator, approved);
    }

    /**
     * @dev Reverts if the `tokenId` doesn't have a current owner (it hasn't been minted, or it has been burned).
     * Returns the owner.
     *
     * Overrides to ownership logic should be done to {_ownerOf}.
     */
    function _requireOwned(uint256 tokenId) internal view returns (address) {
        address owner = _ownerOf(tokenId);
        if (owner == address(0)) {
            revert ERC721NonexistentToken(tokenId);
        }
        return owner;
    }

    /**
     * @dev Private function to invoke {IERC721Receiver-onERC721Received} on a target address. This will revert if the
     * recipient doesn't accept the token transfer. 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
     */
    function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory data) private {
        if (to.code.length > 0) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, data) returns (bytes4 retval) {
                if (retval != IERC721Receiver.onERC721Received.selector) {
                    revert ERC721InvalidReceiver(to);
                }
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert ERC721InvalidReceiver(to);
                } else {
                    /// @solidity memory-safe-assembly
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC721/extensions/ERC721Enumerable.sol)

pragma solidity ^0.8.20;

import {ERC721} from "../ERC721.sol";
import {IERC721Enumerable} from "./IERC721Enumerable.sol";
import {IERC165} from "../../../utils/introspection/ERC165.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.
 *
 * CAUTION: `ERC721` extensions that implement custom `balanceOf` logic, such as `ERC721Consecutive`,
 * interfere with enumerability and should not be used together with `ERC721Enumerable`.
 */
abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {
    mapping(address owner => mapping(uint256 index => uint256)) private _ownedTokens;
    mapping(uint256 tokenId => uint256) private _ownedTokensIndex;

    uint256[] private _allTokens;
    mapping(uint256 tokenId => uint256) private _allTokensIndex;

    /**
     * @dev An `owner`'s token query was out of bounds for `index`.
     *
     * NOTE: The owner being `address(0)` indicates a global out of bounds index.
     */
    error ERC721OutOfBoundsIndex(address owner, uint256 index);

    /**
     * @dev Batch mint is not allowed.
     */
    error ERC721EnumerableForbiddenBatchMint();

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165, ERC721) returns (bool) {
        return interfaceId == type(IERC721Enumerable).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) public view virtual returns (uint256) {
        if (index >= balanceOf(owner)) {
            revert ERC721OutOfBoundsIndex(owner, index);
        }
        return _ownedTokens[owner][index];
    }

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

    /**
     * @dev See {IERC721Enumerable-tokenByIndex}.
     */
    function tokenByIndex(uint256 index) public view virtual returns (uint256) {
        if (index >= totalSupply()) {
            revert ERC721OutOfBoundsIndex(address(0), index);
        }
        return _allTokens[index];
    }

    /**
     * @dev See {ERC721-_update}.
     */
    function _update(address to, uint256 tokenId, address auth) internal virtual override returns (address) {
        address previousOwner = super._update(to, tokenId, auth);

        if (previousOwner == address(0)) {
            _addTokenToAllTokensEnumeration(tokenId);
        } else if (previousOwner != to) {
            _removeTokenFromOwnerEnumeration(previousOwner, tokenId);
        }
        if (to == address(0)) {
            _removeTokenFromAllTokensEnumeration(tokenId);
        } else if (previousOwner != to) {
            _addTokenToOwnerEnumeration(to, tokenId);
        }

        return previousOwner;
    }

    /**
     * @dev Private function to add a token to this extension's ownership-tracking data structures.
     * @param to address representing the new owner of the given token ID
     * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
     */
    function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
        uint256 length = balanceOf(to) - 1;
        _ownedTokens[to][length] = tokenId;
        _ownedTokensIndex[tokenId] = length;
    }

    /**
     * @dev Private function to add a token to this extension's token tracking data structures.
     * @param tokenId uint256 ID of the token to be added to the tokens list
     */
    function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
        _allTokensIndex[tokenId] = _allTokens.length;
        _allTokens.push(tokenId);
    }

    /**
     * @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
     * while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
     * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
     * This has O(1) time complexity, but alters the order of the _ownedTokens array.
     * @param from address representing the previous owner of the given token ID
     * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
     */
    function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId) private {
        // To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = balanceOf(from);
        uint256 tokenIndex = _ownedTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary
        if (tokenIndex != lastTokenIndex) {
            uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];

            _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
            _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
        }

        // This also deletes the contents at the last position of the array
        delete _ownedTokensIndex[tokenId];
        delete _ownedTokens[from][lastTokenIndex];
    }

    /**
     * @dev Private function to remove a token from this extension's token tracking data structures.
     * This has O(1) time complexity, but alters the order of the _allTokens array.
     * @param tokenId uint256 ID of the token to be removed from the tokens list
     */
    function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
        // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = _allTokens.length - 1;
        uint256 tokenIndex = _allTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
        // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
        // an 'if' statement (like in _removeTokenFromOwnerEnumeration)
        uint256 lastTokenId = _allTokens[lastTokenIndex];

        _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
        _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index

        // This also deletes the contents at the last position of the array
        delete _allTokensIndex[tokenId];
        _allTokens.pop();
    }

    /**
     * See {ERC721-_increaseBalance}. We need that to account tokens that were minted in batch
     */
    function _increaseBalance(address account, uint128 amount) internal virtual override {
        if (amount > 0) {
            revert ERC721EnumerableForbiddenBatchMint();
        }
        super._increaseBalance(account, amount);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC721/extensions/IERC721Enumerable.sol)

pragma solidity ^0.8.20;

import {IERC721} from "../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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.20;

import {IERC721} from "../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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.20;

import {IERC165} from "../../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`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon
     *   a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must 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: Note that the caller is responsible to confirm that the recipient is capable of receiving ERC721
     * or else they may be permanently lost. Usage of {safeTransferFrom} prevents loss, though the caller must
     * understand this adds an external call which potentially creates a reentrancy vulnerability.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 tokenId) external;

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

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the address zero.
     *
     * 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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.20;

/**
 * @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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.1) (utils/Context.sol)

pragma solidity ^0.8.20;

/**
 * @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;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/introspection/ERC165.sol)

pragma solidity ^0.8.20;

import {IERC165} from "./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);
 * }
 * ```
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/introspection/IERC165.sol)

pragma solidity ^0.8.20;

/**
 * @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);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/math/Math.sol)

pragma solidity ^0.8.20;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Muldiv operation overflow.
     */
    error MathOverflowedMulDiv();

    enum Rounding {
        Floor, // Toward negative infinity
        Ceil, // Toward positive infinity
        Trunc, // Toward zero
        Expand // Away from zero
    }

    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     */
    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 subtraction of two unsigned integers, with an overflow flag.
     */
    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.
     */
    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.
     */
    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.
     */
    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 largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds towards infinity instead
     * of rounding towards zero.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        if (b == 0) {
            // Guarantee the same behavior as in a regular Solidity division.
            return a / b;
        }

        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a == 0 ? 0 : (a - 1) / b + 1;
    }

    /**
     * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or
     * denominator == 0.
     * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv) with further edits by
     * Uniswap Labs also under MIT license.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
            // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2^256 + prod0.
            uint256 prod0 = x * y; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                // Solidity will revert if denominator == 0, unlike the div opcode on its own.
                // The surrounding unchecked block does not change this fact.
                // See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            if (denominator <= prod1) {
                revert MathOverflowedMulDiv();
            }

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0].
            uint256 remainder;
            assembly {
                // Compute remainder using mulmod.
                remainder := mulmod(x, y, denominator)

                // Subtract 256 bit number from 512 bit number.
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator and compute largest power of two divisor of denominator.
            // Always >= 1. See https://cs.stackexchange.com/q/138556/92363.

            uint256 twos = denominator & (0 - denominator);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

                // Divide [prod1 prod0] by twos.
                prod0 := div(prod0, twos)

                // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                twos := add(div(sub(0, twos), twos), 1)
            }

            // Shift in bits from prod1 into prod0.
            prod0 |= prod1 * twos;

            // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
            // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
            // four bits. That is, denominator * inv = 1 mod 2^4.
            uint256 inverse = (3 * denominator) ^ 2;

            // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also
            // works in modular arithmetic, doubling the correct bits in each step.
            inverse *= 2 - denominator * inverse; // inverse mod 2^8
            inverse *= 2 - denominator * inverse; // inverse mod 2^16
            inverse *= 2 - denominator * inverse; // inverse mod 2^32
            inverse *= 2 - denominator * inverse; // inverse mod 2^64
            inverse *= 2 - denominator * inverse; // inverse mod 2^128
            inverse *= 2 - denominator * inverse; // inverse mod 2^256

            // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
            // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
            // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inverse;
            return result;
        }
    }

    /**
     * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
        uint256 result = mulDiv(x, y, denominator);
        if (unsignedRoundsUp(rounding) && mulmod(x, y, denominator) > 0) {
            result += 1;
        }
        return result;
    }

    /**
     * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded
     * towards zero.
     *
     * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
     */
    function sqrt(uint256 a) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
        //
        // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
        // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
        //
        // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
        // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
        // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
        //
        // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
        uint256 result = 1 << (log2(a) >> 1);

        // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
        // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
        // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
        // into the expected uint128 result.
        unchecked {
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            return min(result, a / result);
        }
    }

    /**
     * @notice Calculates sqrt(a), following the selected rounding direction.
     */
    function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = sqrt(a);
            return result + (unsignedRoundsUp(rounding) && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     */
    function log2(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 128;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 64;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 32;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 16;
            }
            if (value >> 8 > 0) {
                value >>= 8;
                result += 8;
            }
            if (value >> 4 > 0) {
                value >>= 4;
                result += 4;
            }
            if (value >> 2 > 0) {
                value >>= 2;
                result += 2;
            }
            if (value >> 1 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log2(value);
            return result + (unsignedRoundsUp(rounding) && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     */
    function log10(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >= 10 ** 64) {
                value /= 10 ** 64;
                result += 64;
            }
            if (value >= 10 ** 32) {
                value /= 10 ** 32;
                result += 32;
            }
            if (value >= 10 ** 16) {
                value /= 10 ** 16;
                result += 16;
            }
            if (value >= 10 ** 8) {
                value /= 10 ** 8;
                result += 8;
            }
            if (value >= 10 ** 4) {
                value /= 10 ** 4;
                result += 4;
            }
            if (value >= 10 ** 2) {
                value /= 10 ** 2;
                result += 2;
            }
            if (value >= 10 ** 1) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log10(value);
            return result + (unsignedRoundsUp(rounding) && 10 ** result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     *
     * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
     */
    function log256(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 16;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 8;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 4;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 2;
            }
            if (value >> 8 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 256, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (unsignedRoundsUp(rounding) && 1 << (result << 3) < value ? 1 : 0);
        }
    }

    /**
     * @dev Returns whether a provided rounding mode is considered rounding up for unsigned integers.
     */
    function unsignedRoundsUp(Rounding rounding) internal pure returns (bool) {
        return uint8(rounding) % 2 == 1;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/math/SignedMath.sol)

pragma solidity ^0.8.20;

/**
 * @dev Standard signed math utilities missing in the Solidity language.
 */
library SignedMath {
    /**
     * @dev Returns the largest of two signed numbers.
     */
    function max(int256 a, int256 b) internal pure returns (int256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two signed numbers.
     */
    function min(int256 a, int256 b) internal pure returns (int256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two signed numbers without overflow.
     * The result is rounded towards zero.
     */
    function average(int256 a, int256 b) internal pure returns (int256) {
        // Formula from the book "Hacker's Delight"
        int256 x = (a & b) + ((a ^ b) >> 1);
        return x + (int256(uint256(x) >> 255) & (a ^ b));
    }

    /**
     * @dev Returns the absolute unsigned value of a signed value.
     */
    function abs(int256 n) internal pure returns (uint256) {
        unchecked {
            // must be unchecked in order to support `n = type(int256).min`
            return uint256(n >= 0 ? n : -n);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/Strings.sol)

pragma solidity ^0.8.20;

import {Math} from "./math/Math.sol";
import {SignedMath} from "./math/SignedMath.sol";

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant HEX_DIGITS = "0123456789abcdef";
    uint8 private constant ADDRESS_LENGTH = 20;

    /**
     * @dev The `value` string doesn't fit in the specified `length`.
     */
    error StringsInsufficientHexLength(uint256 value, uint256 length);

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = Math.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            /// @solidity memory-safe-assembly
            assembly {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                /// @solidity memory-safe-assembly
                assembly {
                    mstore8(ptr, byte(mod(value, 10), HEX_DIGITS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `int256` to its ASCII `string` decimal representation.
     */
    function toStringSigned(int256 value) internal pure returns (string memory) {
        return string.concat(value < 0 ? "-" : "", toString(SignedMath.abs(value)));
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, Math.log256(value) + 1);
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        uint256 localValue = value;
        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_DIGITS[localValue & 0xf];
            localValue >>= 4;
        }
        if (localValue != 0) {
            revert StringsInsufficientHexLength(value, length);
        }
        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);
    }

    /**
     * @dev Returns true if the two strings are equal.
     */
    function equal(string memory a, string memory b) internal pure returns (bool) {
        return bytes(a).length == bytes(b).length && keccak256(bytes(a)) == keccak256(bytes(b));
    }
}

// SPDX-License-Identifier: MIT
pragma solidity 0.8.26;

import {Strings} from "@openzeppelin/contracts/utils/Strings.sol";
import {ERC721, ERC721Enumerable} from "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {Pseudorandom} from "./lib/Pseudorandom.sol";
import {IDice} from "./interfaces/IDice.sol";
import {IAnyrand} from "./interfaces/IAnyrand.sol";
import {IRandomiserCallbackV3} from "./interfaces/IRandomiserCallbackV3.sol";
import {DiceMetadata} from "./DiceMetadata.sol";

/// @title Dice
/// @custom:version 1.0.0
/// @notice 1 token = 1 die
contract Dice is
    IDice,
    DiceMetadata,
    IRandomiserCallbackV3,
    ERC721Enumerable,
    Ownable
{
    using Strings for uint256;

    /// @notice Callback gas limit for a reveal call
    uint256 public constant CALLBACK_GAS_REVEAL_OVERHEAD = 300_000;
    /// @notice Callback gas limit per quantity of reveal
    uint256 public constant CALLBACK_GAS_PER_REVEAL = 150_000;
    /// @notice Callback gas limit for a roll call
    uint256 public constant CALLBACK_GAS_ROLL_OVERHEAD = 300_000;
    /// @notice Callback gas limit per quantity of roll
    uint256 public constant CALLBACK_GAS_PER_ROLL = 50_000;

    /// @notice Purchase price for a die
    uint256 public immutable price;
    /// @notice Token states
    mapping(uint256 tokenId => TokenState) public tokenStates;
    /// @notice Die rolls
    mapping(uint256 tokenId => uint256[]) public rolls;
    /// @notice Anyrand coordinator
    address internal immutable _randomiser;
    /// @notice Randomness request routing information
    mapping(uint256 requestId => RequestInfo) internal _requestInfos;
    /// @notice Timestamp of mint start
    uint256 public mintStartedAt;
    /// @notice Limited edition model rarity
    TokenRarity public immutable leModelRarity;
    /// @notice Limited edition model index
    uint256 public immutable leModelIdx;
    /// @notice How long the limited edition model is available for
    uint256 public immutable leModelPeriod;
    /// @notice Whether the limited edition model is still available to mint
    bool public isLimitedEditionModelAvailable;
    /// @notice Whether the contract is paused
    bool public isPaused;

    event MintStarted(uint256 timestamp);
    event TokenPurchased(
        uint256 indexed requestId,
        uint256 indexed tokenId,
        address indexed purchaser,
        uint256 price
    );
    event DieRollRequested(uint256 indexed tokenId, uint256 indexed requestId);
    event DieRolled(uint256 indexed tokenId, uint256 nthRoll, uint256 roll);
    event TokenRevealed(uint256 indexed tokenId, TokenMetadata metadata);
    event RandomnessIgnored(uint256 indexed requestId, uint256 randomness);
    event LimitedEditionModelRemoved(TokenRarity rarity, uint256 index);
    event PaymentExcessRefunded(address indexed to, uint256 amount);
    event ExternalURIUpdated(string externalURI);
    event WithdrawSucceeded(address indexed to, uint256 amount);
    event PauseToggled(bool indexed isPaused);

    constructor(
        uint256 price_,
        address randomiser_,
        string memory baseURI_,
        string[][] memory tokenModels_,
        TokenRarity leModelRarity_,
        uint256 leModelIdx_,
        uint256 leModelPeriod_
    )
        DiceMetadata(baseURI_, tokenModels_)
        ERC721("Dice", "DICE")
        Ownable(msg.sender)
    {
        price = price_;
        _randomiser = randomiser_;

        require(
            tokenModels_[uint256(leModelRarity_)].length > 1 &&
                leModelIdx_ < tokenModels_[uint256(leModelRarity_)].length,
            "Dice: min 2 models in same rarity as LE"
        );
        leModelRarity = leModelRarity_;
        leModelIdx = leModelIdx_;
        leModelPeriod = leModelPeriod_;
        isLimitedEditionModelAvailable = true;
    }

    /// @notice Only allow calls after mint has started
    modifier onlyAfterMintStarted() {
        require(mintStartedAt != 0, "Dice: mint not started");
        _;
    }

    /// @notice Only allow calls when the contract is not paused
    modifier whenNotPaused() {
        require(!isPaused, "Dice: contract is paused");
        _;
    }

    /// @notice Toggle contract pause
    /// @param isPaused_ Whether to pause the contract
    function pause(bool isPaused_) external onlyOwner {
        isPaused = isPaused_;
        emit PauseToggled(isPaused_);
    }

    /// @notice Enable minting
    function start() external onlyOwner {
        require(mintStartedAt == 0, "Dice: mint already started");
        mintStartedAt = block.timestamp;
        emit MintStarted(block.timestamp);
    }

    /// @notice Get the randomiser address
    function randomiser() public view virtual returns (address) {
        return _randomiser;
    }

    /// @notice Get the request info for a VRF request ID
    /// @param requestId VRF request ID
    function requestInfos(
        uint256 requestId
    ) external view returns (RequestInfo memory) {
        return _requestInfos[requestId];
    }

    /// @notice Helper function to get purchase price (NFT purchase price + VRF request price)
    /// @param quantity How many to purchase
    function getPurchasePrice(
        uint256 quantity
    ) external view returns (uint256) {
        (uint256 requestPrice, ) = IAnyrand(randomiser()).getRequestPrice(
            CALLBACK_GAS_REVEAL_OVERHEAD + CALLBACK_GAS_PER_REVEAL * quantity
        );
        return quantity * price + requestPrice;
    }

    /// @notice Remove the limited edition model after 48h
    function _removeLimitedEditionModel() internal {
        if (!isLimitedEditionModelAvailable) {
            // Already removed
            return;
        }

        // Not removed -> check if it needs to be removed
        if (block.timestamp < mintStartedAt + leModelPeriod) {
            // LE mint not yet over
            return;
        }

        // Remove the limited edition model
        TokenMetadata[] storage models = _tokenModels[leModelRarity];
        TokenMetadata memory lastModel = models[models.length - 1];
        // Fix (update) the last model's index -- rarity is the same
        lastModel.index = uint248(leModelIdx);
        // Swap LE model with (updated) last model
        models[leModelIdx] = lastModel;
        // Pop last model
        models.pop();
        // Disable this code from ever running again
        isLimitedEditionModelAvailable = false;
        emit LimitedEditionModelRemoved(leModelRarity, leModelIdx);
    }

    /// @notice Purchase di(c)e
    /// @param quantity How many to purchase
    function purchase(
        uint256 quantity
    ) external payable onlyAfterMintStarted whenNotPaused {
        _removeLimitedEditionModel();
        uint256 totalGasLimit = CALLBACK_GAS_REVEAL_OVERHEAD +
            CALLBACK_GAS_PER_REVEAL *
            quantity;
        (uint256 requestPrice, ) = IAnyrand(randomiser()).getRequestPrice(
            totalGasLimit
        );
        uint256 totalPrice = (quantity * price) + requestPrice;
        require(msg.value >= totalPrice, "Dice: insufficient payment");
        if (msg.value > totalPrice) {
            // refund excess
            (bool success, ) = payable(msg.sender).call{
                value: msg.value - totalPrice
            }("");
            require(success, "Dice: Refund failed");
            emit PaymentExcessRefunded(msg.sender, msg.value - totalPrice);
        }

        uint256 startingTokenId = totalSupply() + 1;
        uint256[] memory tokenIds = new uint256[](quantity);
        for (uint256 i = 0; i < quantity; ++i) {
            tokenIds[i] = startingTokenId + i;
            tokenStates[tokenIds[i]] = TokenState.Minted;
        }

        uint256 requestId = IAnyrand(randomiser()).requestRandomness{
            value: requestPrice
        }(block.timestamp + 30 seconds, totalGasLimit);
        _requestInfos[requestId] = RequestInfo({
            kind: RequestKind.Mint,
            tokenIds: tokenIds
        });

        for (uint256 i = 0; i < quantity; ++i) {
            _safeMint(msg.sender, tokenIds[i]);
            emit TokenPurchased(requestId, tokenIds[i], msg.sender, totalPrice);
        }
    }

    /// @notice Helper function to get roll price (VRF request price)
    /// @param quantity How many rolls
    function getRollPrice(uint256 quantity) external view returns (uint256) {
        (uint256 requestPrice, ) = IAnyrand(randomiser()).getRequestPrice(
            CALLBACK_GAS_ROLL_OVERHEAD + CALLBACK_GAS_PER_ROLL * quantity
        );
        return requestPrice;
    }

    /// @notice Roll a die
    /// @param tokenIds Token ids of dice
    function roll(uint256[] calldata tokenIds) external payable whenNotPaused {
        uint256 totalGasLimit = CALLBACK_GAS_ROLL_OVERHEAD +
            CALLBACK_GAS_PER_ROLL *
            tokenIds.length;
        (uint256 requestPrice, ) = IAnyrand(randomiser()).getRequestPrice(
            totalGasLimit
        );
        require(msg.value >= requestPrice, "Dice: insufficient payment");
        if (msg.value > requestPrice) {
            // refund excess
            (bool success, ) = payable(msg.sender).call{
                value: msg.value - requestPrice
            }("");
            require(success, "Dice: refund failed");
            emit PaymentExcessRefunded(msg.sender, msg.value - requestPrice);
        }

        for (uint256 i; i < tokenIds.length; ++i) {
            require(msg.sender == ownerOf(tokenIds[i]), "Dice: invalid sender");
            require(
                tokenStates[tokenIds[i]] == TokenState.Revealed,
                "Dice: token not revealed"
            );
            if (i == 0) continue;
            require(tokenIds[i] > tokenIds[i - 1], "Dice: unsorted tokenIds");
        }

        uint256 requestId = IAnyrand(randomiser()).requestRandomness{
            value: requestPrice
        }(block.timestamp + 30 seconds, totalGasLimit);
        _requestInfos[requestId] = RequestInfo({
            kind: RequestKind.Roll,
            tokenIds: tokenIds
        });

        for (uint256 i = 0; i < tokenIds.length; ++i)
            emit DieRollRequested(tokenIds[i], requestId);
    }

    /// @notice Anyrand callback
    function receiveRandomness(uint256 requestId, uint256 randomness) public {
        require(msg.sender == randomiser(), "Dice: invalid sender");
        RequestInfo storage requestInfo = _requestInfos[requestId];
        RequestKind requestKind = requestInfo.kind;
        requestInfo.kind = RequestKind.Nullified;
        if (requestKind == RequestKind.Mint) {
            // Reveal token
            _reveal(requestInfo.tokenIds, randomness);
            // Initial roll
            _roll(requestInfo.tokenIds, Pseudorandom.derive(randomness));
        } else if (requestKind == RequestKind.Roll) {
            // Roll die
            _roll(requestInfo.tokenIds, randomness);
        } else {
            // Dead request
            emit RandomnessIgnored(requestId, randomness);
        }
    }

    /// @notice Get total rolls for a die
    /// @param tokenId Token ID
    function getTotalRolls(uint256 tokenId) public view returns (uint256) {
        return rolls[tokenId].length;
    }

    /// @notice Roll dice
    /// @param tokenIds Token IDs
    /// @param randomness Seed
    function _roll(uint256[] memory tokenIds, uint256 randomness) internal {
        for (uint256 i; i < tokenIds.length; ++i) {
            uint256 tokenId = tokenIds[i];
            require(
                tokenStates[tokenId] == TokenState.Revealed,
                "Dice: invalid token state"
            );
            uint256 seed = Pseudorandom.derive(abi.encode(tokenId, randomness));
            uint256 y = Pseudorandom.pick(seed, 6);
            rolls[tokenId].push(y);
            uint256 totalRolls = getTotalRolls(tokenId);
            emit DieRolled(tokenId, totalRolls - 1, y);
        }
    }

    /// @notice Calc the rarity of a die from index out of 1_000_000
    /// @param y index
    function calcRarityFromIndex(uint256 y) public pure returns (TokenRarity) {
        assert(y < 1_000_000);
        TokenRarity rarity;
        if (y < 100) {
            // Legendary
            rarity = TokenRarity.Legendary;
        } else if (y < 100 + 5_000) {
            // Epic
            rarity = TokenRarity.Epic;
        } else if (y < 100 + 5_000 + 79_900) {
            // Rare
            rarity = TokenRarity.Rare;
        } else if (y < 100 + 5_000 + 79_900 + 335_000) {
            // Uncommon
            rarity = TokenRarity.Uncommon;
        } else {
            // Common
            rarity = TokenRarity.Common;
        }
        return rarity;
    }

    /// @notice Reveal the rarity of purchased dice
    /// @param tokenIds Token IDs
    /// @param randomness Seed
    function _reveal(uint256[] memory tokenIds, uint256 randomness) internal {
        for (uint256 i; i < tokenIds.length; ++i) {
            uint256 tokenId = tokenIds[i];
            require(
                tokenStates[tokenId] == TokenState.Minted,
                "Dice: invalid token state"
            );
            tokenStates[tokenId] = TokenState.Revealed;
            uint256 seed = Pseudorandom.derive(abi.encode(tokenId, randomness));
            // Derive rarity from seed
            uint256 r = Pseudorandom.pick(seed, 1_000_000);
            TokenRarity rarity = calcRarityFromIndex(r);
            // Derive token metadata from seed
            TokenMetadata[] storage models = _tokenModels[rarity];
            uint256 m = models.length == 1
                ? 0
                : Pseudorandom.pick(Pseudorandom.derive(seed), models.length);
            _assignTokenMetadata(tokenId, rarity, uint240(m));
            emit TokenRevealed(tokenId, models[m]);
        }
    }

    /// @notice Get the token URI for a die
    /// @param tokenId Token ID
    function tokenURI(
        uint256 tokenId
    ) public view virtual override returns (string memory) {
        _requireOwned(tokenId);
        require(
            tokenStates[tokenId] == TokenState.Revealed,
            "Dice: token not revealed"
        );
        return _tokenURI(tokenId);
    }

    /// @notice Get the token details for a die
    /// @param tokenId Token ID
    function getTokenDetails(
        uint256 tokenId
    ) external view returns (string memory uri, uint256 currentRoll) {
        uri = tokenURI(tokenId);
        uint256[] storage tokenRolls = rolls[tokenId];
        // tokenURI should revert unless revealed
        assert(tokenRolls.length > 0);
        return (uri, tokenRolls[tokenRolls.length - 1]);
    }

    /// @notice Set external URI
    /// @param externalURI New external URI
    function setExternalURI(string memory externalURI) external onlyOwner {
        __externalURI = externalURI;
        emit ExternalURIUpdated(externalURI);
    }

    /// @notice Withdraw proceeds
    function withdraw() external onlyOwner {
        uint256 balance = address(this).balance;
        (bool success, ) = msg.sender.call{value: balance}("");
        require(success, "Dice: withdraw failed");
        emit WithdrawSucceeded(msg.sender, balance);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8;

import {Base64} from "solady/src/utils/Base64.sol";
import {LibString} from "solady/src/utils/LibString.sol";
import {IDice} from "./interfaces/IDice.sol";

/// @title DiceMetadata
/// @author Kevin Charm <[email protected]>
/// @notice Generates JSON metadata onchain
abstract contract DiceMetadata is IDice {
    using LibString for uint256;

    struct TokenMetadataPointer {
        bool isAssigned;
        TokenRarity rarity;
        uint240 index;
    }

    /// @notice External URI base for external_url
    string public __externalURI = "https://dice.anyrand.com/dice/?id=";
    /// @notice Base URI for token metadata
    string public __baseURI;
    /// @notice Mapping of rarities to indices of tokenModelIds
    mapping(TokenRarity rarity => TokenMetadata[] models) internal _tokenModels;
    /// @notice Mapping of minted token IDs to models
    mapping(uint256 tokenId => TokenMetadataPointer) internal _tokenMetadatas;

    constructor(string memory baseURI_, string[][] memory tokenModels_) {
        __baseURI = baseURI_;

        require(
            tokenModels_.length == (uint256(type(TokenRarity).max) + 1),
            "Dice: Incomplete rarity set"
        );
        for (uint256 r; r < tokenModels_.length; ++r) {
            TokenRarity rarity = TokenRarity(r);
            string[] memory models = tokenModels_[r];
            require(
                models.length > 0,
                "Dice: Rarity must have at least one model"
            );
            for (uint240 i; i < models.length; ++i) {
                _tokenModels[rarity].push(
                    TokenMetadata({rarity: rarity, index: i, name: models[i]})
                );
            }
        }
    }

    function _assignTokenMetadata(
        uint256 tokenId,
        TokenRarity rarity,
        uint240 index
    ) internal {
        require(
            !_tokenMetadatas[tokenId].isAssigned,
            "Dice: Token metadata already assigned"
        );
        _tokenMetadatas[tokenId] = TokenMetadataPointer({
            isAssigned: true,
            rarity: rarity,
            index: index
        });
    }

    function getTokenModelsByRarity(
        TokenRarity rarity
    ) public view returns (TokenMetadata[] memory) {
        return _tokenModels[rarity];
    }

    function getTokenModel(
        TokenRarity rarity,
        uint240 index
    ) public view returns (TokenMetadata memory) {
        return _tokenModels[rarity][index];
    }

    function getTokenMetadata(
        uint256 tokenId
    ) public view returns (TokenMetadata memory) {
        TokenMetadataPointer memory ptr = _tokenMetadatas[tokenId];
        require(ptr.isAssigned, "Dice: Token metadata not assigned");
        return _tokenModels[ptr.rarity][ptr.index];
    }

    function getRarityName(
        TokenRarity rarity
    ) public pure returns (string memory) {
        if (rarity == TokenRarity.Common) {
            return "Common";
        } else if (rarity == TokenRarity.Uncommon) {
            return "Uncommon";
        } else if (rarity == TokenRarity.Rare) {
            return "Rare";
        } else if (rarity == TokenRarity.Epic) {
            return "Epic";
        } else {
            // if (rarity == TokenRarity.Legendary)
            return "Legendary";
        }
    }

    function _tokenURI(uint256 tokenId) internal view returns (string memory) {
        TokenMetadata memory metadata = getTokenMetadata(tokenId);
        string memory externalURL = string.concat(
            __externalURI,
            tokenId.toString()
        );
        string memory r = uint256(metadata.rarity).toString();
        string memory i = uint256(metadata.index).toString();
        string memory image = string.concat(
            __baseURI,
            "img/",
            r,
            "/",
            i,
            ".png"
        );
        string memory gltf = string.concat(
            __baseURI,
            "gltf/",
            r,
            "/",
            i,
            ".glb"
        );
        string memory tokenIdStr = tokenId.toString();
        return
            string.concat(
                "data:application/json;base64,",
                Base64.encode(
                    abi.encodePacked(
                        '{"name":"Onchain Die #',
                        tokenIdStr,
                        '","description":"Reroll your dice using verifiable randomness on dice.anyrand.com","external_url":"',
                        externalURL,
                        '","image":"',
                        image,
                        '","animation_url":"',
                        gltf,
                        '","attributes": [{"trait_type":"Rarity","value":"',
                        getRarityName(metadata.rarity),
                        '"}, {"trait_type":"Model","value":"',
                        metadata.name,
                        '"}]}'
                    )
                )
            );
    }
}

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8;

interface IAnyrand {
    event RandomnessRequested(
        uint256 indexed requestId,
        address indexed requester,
        bytes32 indexed pubKeyHash,
        uint256 round,
        uint256 callbackGasLimit,
        uint256 feePaid,
        uint256 effectiveFeePerGas
    );
    event RandomnessFulfilled(
        uint256 indexed requestId,
        uint256[] randomWords,
        bool callbackSuccess,
        uint256 actualGasUsed
    );
    event RandomnessCallbackFailed(
        uint256 indexed requestId,
        bytes32 retdata,
        uint256 gasLimit,
        uint256 actualGasUsed
    );
    event RequestPremiumMultiplierUpdated(uint256 newPrice);
    event ETHWithdrawn(uint256 amount);
    event BeaconUpdated(address indexed newBeacon);
    event MaxCallbackGasLimitUpdated(uint256 newMaxCallbackGasLimit);
    event MaxDeadlineDeltaUpdated(uint256 maxDeadlineDelta);
    event GasStationUpdated(address indexed newGasStation);
    event MaxFeePerGasUpdated(uint256 maxFeePerGas);

    error TransferFailed(address to, uint256 value);
    error IncorrectPayment(uint256 got, uint256 want);
    error OverGasLimit(uint256 callbackGasLimit);
    error InvalidRequestHash(bytes32 requestHash);
    error InvalidDeadline(uint256 deadline);
    error InsufficientGas();
    error InvalidBeacon(address beacon);

    /// @notice Compute the total request price
    /// @param callbackGasLimit The callback gas limit that will be used for
    ///     the randomness request
    function getRequestPrice(
        uint256 callbackGasLimit
    ) external view returns (uint256 totalPrice, uint256 effectiveFeePerGas);

    /// @notice Request randomness
    /// @param deadline Timestamp of when the randomness should be fulfilled. A
    ///     beacon round closest to this timestamp (rounding up to the nearest
    ///     future round) will be used as the round from which to derive
    ///     randomness.
    /// @param callbackGasLimit Gas limit for callback
    function requestRandomness(
        uint256 deadline,
        uint256 callbackGasLimit
    ) external payable returns (uint256);
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8;

interface IDice {
    enum TokenState {
        Unminted,
        Minted,
        Revealed
    }

    enum TokenRarity {
        Common,
        Uncommon,
        Rare,
        Epic,
        Legendary
    }

    /// @notice Represents metadata for a type of die
    struct TokenMetadata {
        /// @notice Rarity of the die
        TokenRarity rarity;
        /// @notice Index of the die in the rarity set
        uint248 index;
        /// @notice Name/value of the trait
        string name;
    }

    enum RequestKind {
        Nullified,
        Mint,
        Roll
    }

    struct RequestInfo {
        RequestKind kind;
        uint256[] tokenIds;
    }
}

// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity ^0.8;

interface IRandomiserCallbackV3 {
    /// @notice Receive random words from a randomiser.
    /// @dev Ensure that proper access control is enforced on this function;
    ///     only the designated randomiser may call this function and the
    ///     requestId should be as expected from the randomness request.
    /// @param requestId The identifier for the original randomness request
    /// @param randomWord Uniform random number in the range [0, 2**256)
    function receiveRandomness(uint256 requestId, uint256 randomWord) external;
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8;

/// @title Pseudorandom
/// @author Kevin Charm <[email protected]>
/// @notice Pseudorandom. Not to be confused with the cat known as pseudotheos.
library Pseudorandom {
    uint256 private constant _UINT256_MAX = type(uint256).max;

    /// @notice Derive a pseudorandom number from a seed using bytes
    /// @param seed The input to derive from
    /// @return output keccak256(seed)
    function derive(bytes memory seed) internal pure returns (uint256 output) {
        assembly {
            let len := mload(seed)
            output := keccak256(add(seed, 0x20), len)
        }
    }

    /// @notice Derive a pseudorandom number from a seed using u256
    /// @param seed The input to derive from
    /// @return output keccak256(seed)
    function derive(uint256 seed) internal pure returns (uint256 output) {
        assembly {
            mstore(0x00, seed)
            output := keccak256(0x00, 0x20)
        }
    }

    /// @notice Derive a uniform random number in the range [0, max) from seed
    ///     without modulo bias.
    /// @param seed The input to derive from
    /// @param max The upper bound of the range
    /// @return A pseudorandom number in the range [0, max)
    function pick(uint256 seed, uint256 max) internal pure returns (uint256) {
        // modulo reduction of _UINT256_MAX by max
        uint256 ceiling = _UINT256_MAX - (_UINT256_MAX % max);
        uint256 candidate;
        do {
            candidate = derive(seed);
        } while (candidate >= ceiling);
        return candidate % max;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

/// @notice Library to encode strings in Base64.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/utils/Base64.sol)
/// @author Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/Base64.sol)
/// @author Modified from (https://github.com/Brechtpd/base64/blob/main/base64.sol) by Brecht Devos - <[email protected]>.
library Base64 {
    /// @dev Encodes `data` using the base64 encoding described in RFC 4648.
    /// See: https://datatracker.ietf.org/doc/html/rfc4648
    /// @param fileSafe  Whether to replace '+' with '-' and '/' with '_'.
    /// @param noPadding Whether to strip away the padding.
    function encode(bytes memory data, bool fileSafe, bool noPadding)
        internal
        pure
        returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let dataLength := mload(data)

            if dataLength {
                // Multiply by 4/3 rounded up.
                // The `shl(2, ...)` is equivalent to multiplying by 4.
                let encodedLength := shl(2, div(add(dataLength, 2), 3))

                // Set `result` to point to the start of the free memory.
                result := mload(0x40)

                // Store the table into the scratch space.
                // Offsetted by -1 byte so that the `mload` will load the character.
                // We will rewrite the free memory pointer at `0x40` later with
                // the allocated size.
                // The magic constant 0x0670 will turn "-_" into "+/".
                mstore(0x1f, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef")
                mstore(0x3f, xor("ghijklmnopqrstuvwxyz0123456789-_", mul(iszero(fileSafe), 0x0670)))

                // Skip the first slot, which stores the length.
                let ptr := add(result, 0x20)
                let end := add(ptr, encodedLength)

                let dataEnd := add(add(0x20, data), dataLength)
                let dataEndValue := mload(dataEnd) // Cache the value at the `dataEnd` slot.
                mstore(dataEnd, 0x00) // Zeroize the `dataEnd` slot to clear dirty bits.

                // Run over the input, 3 bytes at a time.
                for {} 1 {} {
                    data := add(data, 3) // Advance 3 bytes.
                    let input := mload(data)

                    // Write 4 bytes. Optimized for fewer stack operations.
                    mstore8(0, mload(and(shr(18, input), 0x3F)))
                    mstore8(1, mload(and(shr(12, input), 0x3F)))
                    mstore8(2, mload(and(shr(6, input), 0x3F)))
                    mstore8(3, mload(and(input, 0x3F)))
                    mstore(ptr, mload(0x00))

                    ptr := add(ptr, 4) // Advance 4 bytes.
                    if iszero(lt(ptr, end)) { break }
                }
                mstore(dataEnd, dataEndValue) // Restore the cached value at `dataEnd`.
                mstore(0x40, add(end, 0x20)) // Allocate the memory.
                // Equivalent to `o = [0, 2, 1][dataLength % 3]`.
                let o := div(2, mod(dataLength, 3))
                // Offset `ptr` and pad with '='. We can simply write over the end.
                mstore(sub(ptr, o), shl(240, 0x3d3d))
                // Set `o` to zero if there is padding.
                o := mul(iszero(iszero(noPadding)), o)
                mstore(sub(ptr, o), 0) // Zeroize the slot after the string.
                mstore(result, sub(encodedLength, o)) // Store the length.
            }
        }
    }

    /// @dev Encodes `data` using the base64 encoding described in RFC 4648.
    /// Equivalent to `encode(data, false, false)`.
    function encode(bytes memory data) internal pure returns (string memory result) {
        result = encode(data, false, false);
    }

    /// @dev Encodes `data` using the base64 encoding described in RFC 4648.
    /// Equivalent to `encode(data, fileSafe, false)`.
    function encode(bytes memory data, bool fileSafe)
        internal
        pure
        returns (string memory result)
    {
        result = encode(data, fileSafe, false);
    }

    /// @dev Decodes base64 encoded `data`.
    ///
    /// Supports:
    /// - RFC 4648 (both standard and file-safe mode).
    /// - RFC 3501 (63: ',').
    ///
    /// Does not support:
    /// - Line breaks.
    ///
    /// Note: For performance reasons,
    /// this function will NOT revert on invalid `data` inputs.
    /// Outputs for invalid inputs will simply be undefined behaviour.
    /// It is the user's responsibility to ensure that the `data`
    /// is a valid base64 encoded string.
    function decode(string memory data) internal pure returns (bytes memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            let dataLength := mload(data)

            if dataLength {
                let decodedLength := mul(shr(2, dataLength), 3)

                for {} 1 {} {
                    // If padded.
                    if iszero(and(dataLength, 3)) {
                        let t := xor(mload(add(data, dataLength)), 0x3d3d)
                        // forgefmt: disable-next-item
                        decodedLength := sub(
                            decodedLength,
                            add(iszero(byte(30, t)), iszero(byte(31, t)))
                        )
                        break
                    }
                    // If non-padded.
                    decodedLength := add(decodedLength, sub(and(dataLength, 3), 1))
                    break
                }
                result := mload(0x40)

                // Write the length of the bytes.
                mstore(result, decodedLength)

                // Skip the first slot, which stores the length.
                let ptr := add(result, 0x20)
                let end := add(ptr, decodedLength)

                // Load the table into the scratch space.
                // Constants are optimized for smaller bytecode with zero gas overhead.
                // `m` also doubles as the mask of the upper 6 bits.
                let m := 0xfc000000fc00686c7074787c8084888c9094989ca0a4a8acb0b4b8bcc0c4c8cc
                mstore(0x5b, m)
                mstore(0x3b, 0x04080c1014181c2024282c3034383c4044484c5054585c6064)
                mstore(0x1a, 0xf8fcf800fcd0d4d8dce0e4e8ecf0f4)

                for {} 1 {} {
                    // Read 4 bytes.
                    data := add(data, 4)
                    let input := mload(data)

                    // Write 3 bytes.
                    // forgefmt: disable-next-item
                    mstore(ptr, or(
                        and(m, mload(byte(28, input))),
                        shr(6, or(
                            and(m, mload(byte(29, input))),
                            shr(6, or(
                                and(m, mload(byte(30, input))),
                                shr(6, mload(byte(31, input)))
                            ))
                        ))
                    ))
                    ptr := add(ptr, 3)
                    if iszero(lt(ptr, end)) { break }
                }
                mstore(0x40, add(end, 0x20)) // Allocate the memory.
                mstore(end, 0) // Zeroize the slot after the bytes.
                mstore(0x60, 0) // Restore the zero slot.
            }
        }
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

/// @notice Library for converting numbers into strings and other string operations.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/utils/LibString.sol)
/// @author Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/LibString.sol)
///
/// @dev Note:
/// For performance and bytecode compactness, most of the string operations are restricted to
/// byte strings (7-bit ASCII), except where otherwise specified.
/// Usage of byte string operations on charsets with runes spanning two or more bytes
/// can lead to undefined behavior.
library LibString {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                        CUSTOM ERRORS                       */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The length of the output is too small to contain all the hex digits.
    error HexLengthInsufficient();

    /// @dev The length of the string is more than 32 bytes.
    error TooBigForSmallString();

    /// @dev The input string must be a 7-bit ASCII.
    error StringNot7BitASCII();

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                         CONSTANTS                          */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The constant returned when the `search` is not found in the string.
    uint256 internal constant NOT_FOUND = type(uint256).max;

    /// @dev Lookup for '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'.
    uint128 internal constant ALPHANUMERIC_7_BIT_ASCII = 0x7fffffe07fffffe03ff000000000000;

    /// @dev Lookup for 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'.
    uint128 internal constant LETTERS_7_BIT_ASCII = 0x7fffffe07fffffe0000000000000000;

    /// @dev Lookup for 'abcdefghijklmnopqrstuvwxyz'.
    uint128 internal constant LOWERCASE_7_BIT_ASCII = 0x7fffffe000000000000000000000000;

    /// @dev Lookup for 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'.
    uint128 internal constant UPPERCASE_7_BIT_ASCII = 0x7fffffe0000000000000000;

    /// @dev Lookup for '0123456789'.
    uint128 internal constant DIGITS_7_BIT_ASCII = 0x3ff000000000000;

    /// @dev Lookup for '0123456789abcdefABCDEF'.
    uint128 internal constant HEXDIGITS_7_BIT_ASCII = 0x7e0000007e03ff000000000000;

    /// @dev Lookup for '01234567'.
    uint128 internal constant OCTDIGITS_7_BIT_ASCII = 0xff000000000000;

    /// @dev Lookup for '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~ \t\n\r\x0b\x0c'.
    uint128 internal constant PRINTABLE_7_BIT_ASCII = 0x7fffffffffffffffffffffff00003e00;

    /// @dev Lookup for '!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~'.
    uint128 internal constant PUNCTUATION_7_BIT_ASCII = 0x78000001f8000001fc00fffe00000000;

    /// @dev Lookup for ' \t\n\r\x0b\x0c'.
    uint128 internal constant WHITESPACE_7_BIT_ASCII = 0x100003e00;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     DECIMAL OPERATIONS                     */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the base 10 decimal representation of `value`.
    function toString(uint256 value) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            // The maximum value of a uint256 contains 78 digits (1 byte per digit), but
            // we allocate 0xa0 bytes to keep the free memory pointer 32-byte word aligned.
            // We will need 1 word for the trailing zeros padding, 1 word for the length,
            // and 3 words for a maximum of 78 digits.
            result := add(mload(0x40), 0x80)
            mstore(0x40, add(result, 0x20)) // Allocate memory.
            mstore(result, 0) // Zeroize the slot after the string.

            let end := result // Cache the end of the memory to calculate the length later.
            let w := not(0) // Tsk.
            // We write the string from rightmost digit to leftmost digit.
            // The following is essentially a do-while loop that also handles the zero case.
            for { let temp := value } 1 {} {
                result := add(result, w) // `sub(result, 1)`.
                // Store the character to the pointer.
                // The ASCII index of the '0' character is 48.
                mstore8(result, add(48, mod(temp, 10)))
                temp := div(temp, 10) // Keep dividing `temp` until zero.
                if iszero(temp) { break }
            }
            let n := sub(end, result)
            result := sub(result, 0x20) // Move the pointer 32 bytes back to make room for the length.
            mstore(result, n) // Store the length.
        }
    }

    /// @dev Returns the base 10 decimal representation of `value`.
    function toString(int256 value) internal pure returns (string memory result) {
        if (value >= 0) return toString(uint256(value));
        unchecked {
            result = toString(~uint256(value) + 1);
        }
        /// @solidity memory-safe-assembly
        assembly {
            // We still have some spare memory space on the left,
            // as we have allocated 3 words (96 bytes) for up to 78 digits.
            let n := mload(result) // Load the string length.
            mstore(result, 0x2d) // Store the '-' character.
            result := sub(result, 1) // Move back the string pointer by a byte.
            mstore(result, add(n, 1)) // Update the string length.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   HEXADECIMAL OPERATIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the hexadecimal representation of `value`,
    /// left-padded to an input length of `length` bytes.
    /// The output is prefixed with "0x" encoded using 2 hexadecimal digits per byte,
    /// giving a total length of `length * 2 + 2` bytes.
    /// Reverts if `length` is too small for the output to contain all the digits.
    function toHexString(uint256 value, uint256 length)
        internal
        pure
        returns (string memory result)
    {
        result = toHexStringNoPrefix(value, length);
        /// @solidity memory-safe-assembly
        assembly {
            let n := add(mload(result), 2) // Compute the length.
            mstore(result, 0x3078) // Store the "0x" prefix.
            result := sub(result, 2) // Move the pointer.
            mstore(result, n) // Store the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`,
    /// left-padded to an input length of `length` bytes.
    /// The output is not prefixed with "0x" and is encoded using 2 hexadecimal digits per byte,
    /// giving a total length of `length * 2` bytes.
    /// Reverts if `length` is too small for the output to contain all the digits.
    function toHexStringNoPrefix(uint256 value, uint256 length)
        internal
        pure
        returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            // We need 0x20 bytes for the trailing zeros padding, `length * 2` bytes
            // for the digits, 0x02 bytes for the prefix, and 0x20 bytes for the length.
            // We add 0x20 to the total and round down to a multiple of 0x20.
            // (0x20 + 0x20 + 0x02 + 0x20) = 0x62.
            result := add(mload(0x40), and(add(shl(1, length), 0x42), not(0x1f)))
            mstore(0x40, add(result, 0x20)) // Allocate memory.
            mstore(result, 0) // Zeroize the slot after the string.

            let end := result // Cache the end to calculate the length later.
            // Store "0123456789abcdef" in scratch space.
            mstore(0x0f, 0x30313233343536373839616263646566)

            let start := sub(result, add(length, length))
            let w := not(1) // Tsk.
            let temp := value
            // We write the string from rightmost digit to leftmost digit.
            // The following is essentially a do-while loop that also handles the zero case.
            for {} 1 {} {
                result := add(result, w) // `sub(result, 2)`.
                mstore8(add(result, 1), mload(and(temp, 15)))
                mstore8(result, mload(and(shr(4, temp), 15)))
                temp := shr(8, temp)
                if iszero(xor(result, start)) { break }
            }
            if temp {
                mstore(0x00, 0x2194895a) // `HexLengthInsufficient()`.
                revert(0x1c, 0x04)
            }
            let n := sub(end, result)
            result := sub(result, 0x20)
            mstore(result, n) // Store the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x" and encoded using 2 hexadecimal digits per byte.
    /// As address are 20 bytes long, the output will left-padded to have
    /// a length of `20 * 2 + 2` bytes.
    function toHexString(uint256 value) internal pure returns (string memory result) {
        result = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let n := add(mload(result), 2) // Compute the length.
            mstore(result, 0x3078) // Store the "0x" prefix.
            result := sub(result, 2) // Move the pointer.
            mstore(result, n) // Store the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x".
    /// The output excludes leading "0" from the `toHexString` output.
    /// `0x00: "0x0", 0x01: "0x1", 0x12: "0x12", 0x123: "0x123"`.
    function toMinimalHexString(uint256 value) internal pure returns (string memory result) {
        result = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let o := eq(byte(0, mload(add(result, 0x20))), 0x30) // Whether leading zero is present.
            let n := add(mload(result), 2) // Compute the length.
            mstore(add(result, o), 0x3078) // Store the "0x" prefix, accounting for leading zero.
            result := sub(add(result, o), 2) // Move the pointer, accounting for leading zero.
            mstore(result, sub(n, o)) // Store the length, accounting for leading zero.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output excludes leading "0" from the `toHexStringNoPrefix` output.
    /// `0x00: "0", 0x01: "1", 0x12: "12", 0x123: "123"`.
    function toMinimalHexStringNoPrefix(uint256 value)
        internal
        pure
        returns (string memory result)
    {
        result = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let o := eq(byte(0, mload(add(result, 0x20))), 0x30) // Whether leading zero is present.
            let n := mload(result) // Get the length.
            result := add(result, o) // Move the pointer, accounting for leading zero.
            mstore(result, sub(n, o)) // Store the length, accounting for leading zero.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is encoded using 2 hexadecimal digits per byte.
    /// As address are 20 bytes long, the output will left-padded to have
    /// a length of `20 * 2` bytes.
    function toHexStringNoPrefix(uint256 value) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            // We need 0x20 bytes for the trailing zeros padding, 0x20 bytes for the length,
            // 0x02 bytes for the prefix, and 0x40 bytes for the digits.
            // The next multiple of 0x20 above (0x20 + 0x20 + 0x02 + 0x40) is 0xa0.
            result := add(mload(0x40), 0x80)
            mstore(0x40, add(result, 0x20)) // Allocate memory.
            mstore(result, 0) // Zeroize the slot after the string.

            let end := result // Cache the end to calculate the length later.
            mstore(0x0f, 0x30313233343536373839616263646566) // Store the "0123456789abcdef" lookup.

            let w := not(1) // Tsk.
            // We write the string from rightmost digit to leftmost digit.
            // The following is essentially a do-while loop that also handles the zero case.
            for { let temp := value } 1 {} {
                result := add(result, w) // `sub(result, 2)`.
                mstore8(add(result, 1), mload(and(temp, 15)))
                mstore8(result, mload(and(shr(4, temp), 15)))
                temp := shr(8, temp)
                if iszero(temp) { break }
            }
            let n := sub(end, result)
            result := sub(result, 0x20)
            mstore(result, n) // Store the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x", encoded using 2 hexadecimal digits per byte,
    /// and the alphabets are capitalized conditionally according to
    /// https://eips.ethereum.org/EIPS/eip-55
    function toHexStringChecksummed(address value) internal pure returns (string memory result) {
        result = toHexString(value);
        /// @solidity memory-safe-assembly
        assembly {
            let mask := shl(6, div(not(0), 255)) // `0b010000000100000000 ...`
            let o := add(result, 0x22)
            let hashed := and(keccak256(o, 40), mul(34, mask)) // `0b10001000 ... `
            let t := shl(240, 136) // `0b10001000 << 240`
            for { let i := 0 } 1 {} {
                mstore(add(i, i), mul(t, byte(i, hashed)))
                i := add(i, 1)
                if eq(i, 20) { break }
            }
            mstore(o, xor(mload(o), shr(1, and(mload(0x00), and(mload(o), mask)))))
            o := add(o, 0x20)
            mstore(o, xor(mload(o), shr(1, and(mload(0x20), and(mload(o), mask)))))
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x" and encoded using 2 hexadecimal digits per byte.
    function toHexString(address value) internal pure returns (string memory result) {
        result = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let n := add(mload(result), 2) // Compute the length.
            mstore(result, 0x3078) // Store the "0x" prefix.
            result := sub(result, 2) // Move the pointer.
            mstore(result, n) // Store the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is encoded using 2 hexadecimal digits per byte.
    function toHexStringNoPrefix(address value) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            // Allocate memory.
            // We need 0x20 bytes for the trailing zeros padding, 0x20 bytes for the length,
            // 0x02 bytes for the prefix, and 0x28 bytes for the digits.
            // The next multiple of 0x20 above (0x20 + 0x20 + 0x02 + 0x28) is 0x80.
            mstore(0x40, add(result, 0x80))
            mstore(0x0f, 0x30313233343536373839616263646566) // Store the "0123456789abcdef" lookup.

            result := add(result, 2)
            mstore(result, 40) // Store the length.
            let o := add(result, 0x20)
            mstore(add(o, 40), 0) // Zeroize the slot after the string.
            value := shl(96, value)
            // We write the string from rightmost digit to leftmost digit.
            // The following is essentially a do-while loop that also handles the zero case.
            for { let i := 0 } 1 {} {
                let p := add(o, add(i, i))
                let temp := byte(i, value)
                mstore8(add(p, 1), mload(and(temp, 15)))
                mstore8(p, mload(shr(4, temp)))
                i := add(i, 1)
                if eq(i, 20) { break }
            }
        }
    }

    /// @dev Returns the hex encoded string from the raw bytes.
    /// The output is encoded using 2 hexadecimal digits per byte.
    function toHexString(bytes memory raw) internal pure returns (string memory result) {
        result = toHexStringNoPrefix(raw);
        /// @solidity memory-safe-assembly
        assembly {
            let n := add(mload(result), 2) // Compute the length.
            mstore(result, 0x3078) // Store the "0x" prefix.
            result := sub(result, 2) // Move the pointer.
            mstore(result, n) // Store the length.
        }
    }

    /// @dev Returns the hex encoded string from the raw bytes.
    /// The output is encoded using 2 hexadecimal digits per byte.
    function toHexStringNoPrefix(bytes memory raw) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            let n := mload(raw)
            result := add(mload(0x40), 2) // Skip 2 bytes for the optional prefix.
            mstore(result, add(n, n)) // Store the length of the output.

            mstore(0x0f, 0x30313233343536373839616263646566) // Store the "0123456789abcdef" lookup.
            let o := add(result, 0x20)
            let end := add(raw, n)
            for {} iszero(eq(raw, end)) {} {
                raw := add(raw, 1)
                mstore8(add(o, 1), mload(and(mload(raw), 15)))
                mstore8(o, mload(and(shr(4, mload(raw)), 15)))
                o := add(o, 2)
            }
            mstore(o, 0) // Zeroize the slot after the string.
            mstore(0x40, add(o, 0x20)) // Allocate memory.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   RUNE STRING OPERATIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the number of UTF characters in the string.
    function runeCount(string memory s) internal pure returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            if mload(s) {
                mstore(0x00, div(not(0), 255))
                mstore(0x20, 0x0202020202020202020202020202020202020202020202020303030304040506)
                let o := add(s, 0x20)
                let end := add(o, mload(s))
                for { result := 1 } 1 { result := add(result, 1) } {
                    o := add(o, byte(0, mload(shr(250, mload(o)))))
                    if iszero(lt(o, end)) { break }
                }
            }
        }
    }

    /// @dev Returns if this string is a 7-bit ASCII string.
    /// (i.e. all characters codes are in [0..127])
    function is7BitASCII(string memory s) internal pure returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := 1
            let mask := shl(7, div(not(0), 255))
            let n := mload(s)
            if n {
                let o := add(s, 0x20)
                let end := add(o, n)
                let last := mload(end)
                mstore(end, 0)
                for {} 1 {} {
                    if and(mask, mload(o)) {
                        result := 0
                        break
                    }
                    o := add(o, 0x20)
                    if iszero(lt(o, end)) { break }
                }
                mstore(end, last)
            }
        }
    }

    /// @dev Returns if this string is a 7-bit ASCII string,
    /// AND all characters are in the `allowed` lookup.
    /// Note: If `s` is empty, returns true regardless of `allowed`.
    function is7BitASCII(string memory s, uint128 allowed) internal pure returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := 1
            if mload(s) {
                let allowed_ := shr(128, shl(128, allowed))
                let o := add(s, 0x20)
                for { let end := add(o, mload(s)) } 1 {} {
                    result := and(result, shr(byte(0, mload(o)), allowed_))
                    o := add(o, 1)
                    if iszero(and(result, lt(o, end))) { break }
                }
            }
        }
    }

    /// @dev Converts the bytes in the 7-bit ASCII string `s` to
    /// an allowed lookup for use in `is7BitASCII(s, allowed)`.
    /// To save runtime gas, you can cache the result in an immutable variable.
    function to7BitASCIIAllowedLookup(string memory s) internal pure returns (uint128 result) {
        /// @solidity memory-safe-assembly
        assembly {
            if mload(s) {
                let o := add(s, 0x20)
                for { let end := add(o, mload(s)) } 1 {} {
                    result := or(result, shl(byte(0, mload(o)), 1))
                    o := add(o, 1)
                    if iszero(lt(o, end)) { break }
                }
                if shr(128, result) {
                    mstore(0x00, 0xc9807e0d) // `StringNot7BitASCII()`.
                    revert(0x1c, 0x04)
                }
            }
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   BYTE STRING OPERATIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    // For performance and bytecode compactness, byte string operations are restricted
    // to 7-bit ASCII strings. All offsets are byte offsets, not UTF character offsets.
    // Usage of byte string operations on charsets with runes spanning two or more bytes
    // can lead to undefined behavior.

    /// @dev Returns `subject` all occurrences of `needle` replaced with `replacement`.
    function replace(string memory subject, string memory needle, string memory replacement)
        internal
        pure
        returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            let needleLen := mload(needle)
            let replacementLen := mload(replacement)
            let d := sub(result, subject) // Memory difference.
            let i := add(subject, 0x20) // Subject bytes pointer.
            let end := add(i, mload(subject))
            if iszero(gt(needleLen, mload(subject))) {
                let subjectSearchEnd := add(sub(end, needleLen), 1)
                let h := 0 // The hash of `needle`.
                if iszero(lt(needleLen, 0x20)) { h := keccak256(add(needle, 0x20), needleLen) }
                let s := mload(add(needle, 0x20))
                for { let m := shl(3, sub(0x20, and(needleLen, 0x1f))) } 1 {} {
                    let t := mload(i)
                    // Whether the first `needleLen % 32` bytes of `subject` and `needle` matches.
                    if iszero(shr(m, xor(t, s))) {
                        if h {
                            if iszero(eq(keccak256(i, needleLen), h)) {
                                mstore(add(i, d), t)
                                i := add(i, 1)
                                if iszero(lt(i, subjectSearchEnd)) { break }
                                continue
                            }
                        }
                        // Copy the `replacement` one word at a time.
                        for { let j := 0 } 1 {} {
                            mstore(add(add(i, d), j), mload(add(add(replacement, 0x20), j)))
                            j := add(j, 0x20)
                            if iszero(lt(j, replacementLen)) { break }
                        }
                        d := sub(add(d, replacementLen), needleLen)
                        if needleLen {
                            i := add(i, needleLen)
                            if iszero(lt(i, subjectSearchEnd)) { break }
                            continue
                        }
                    }
                    mstore(add(i, d), t)
                    i := add(i, 1)
                    if iszero(lt(i, subjectSearchEnd)) { break }
                }
            }
            let n := add(sub(d, add(result, 0x20)), end)
            // Copy the rest of the string one word at a time.
            for {} lt(i, end) { i := add(i, 0x20) } { mstore(add(i, d), mload(i)) }
            let o := add(i, d)
            mstore(o, 0) // Zeroize the slot after the string.
            mstore(0x40, add(o, 0x20)) // Allocate memory.
            mstore(result, n) // Store the length.
        }
    }

    /// @dev Returns the byte index of the first location of `needle` in `subject`,
    /// needleing from left to right, starting from `from`.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `needle` is not found.
    function indexOf(string memory subject, string memory needle, uint256 from)
        internal
        pure
        returns (uint256 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            result := not(0) // Initialize to `NOT_FOUND`.
            for { let subjectLen := mload(subject) } 1 {} {
                if iszero(mload(needle)) {
                    result := from
                    if iszero(gt(from, subjectLen)) { break }
                    result := subjectLen
                    break
                }
                let needleLen := mload(needle)
                let subjectStart := add(subject, 0x20)

                subject := add(subjectStart, from)
                let end := add(sub(add(subjectStart, subjectLen), needleLen), 1)
                let m := shl(3, sub(0x20, and(needleLen, 0x1f)))
                let s := mload(add(needle, 0x20))

                if iszero(and(lt(subject, end), lt(from, subjectLen))) { break }

                if iszero(lt(needleLen, 0x20)) {
                    for { let h := keccak256(add(needle, 0x20), needleLen) } 1 {} {
                        if iszero(shr(m, xor(mload(subject), s))) {
                            if eq(keccak256(subject, needleLen), h) {
                                result := sub(subject, subjectStart)
                                break
                            }
                        }
                        subject := add(subject, 1)
                        if iszero(lt(subject, end)) { break }
                    }
                    break
                }
                for {} 1 {} {
                    if iszero(shr(m, xor(mload(subject), s))) {
                        result := sub(subject, subjectStart)
                        break
                    }
                    subject := add(subject, 1)
                    if iszero(lt(subject, end)) { break }
                }
                break
            }
        }
    }

    /// @dev Returns the byte index of the first location of `needle` in `subject`,
    /// needleing from left to right.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `needle` is not found.
    function indexOf(string memory subject, string memory needle)
        internal
        pure
        returns (uint256 result)
    {
        result = indexOf(subject, needle, 0);
    }

    /// @dev Returns the byte index of the first location of `needle` in `subject`,
    /// needleing from right to left, starting from `from`.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `needle` is not found.
    function lastIndexOf(string memory subject, string memory needle, uint256 from)
        internal
        pure
        returns (uint256 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            for {} 1 {} {
                result := not(0) // Initialize to `NOT_FOUND`.
                let needleLen := mload(needle)
                if gt(needleLen, mload(subject)) { break }
                let w := result

                let fromMax := sub(mload(subject), needleLen)
                if iszero(gt(fromMax, from)) { from := fromMax }

                let end := add(add(subject, 0x20), w)
                subject := add(add(subject, 0x20), from)
                if iszero(gt(subject, end)) { break }
                // As this function is not too often used,
                // we shall simply use keccak256 for smaller bytecode size.
                for { let h := keccak256(add(needle, 0x20), needleLen) } 1 {} {
                    if eq(keccak256(subject, needleLen), h) {
                        result := sub(subject, add(end, 1))
                        break
                    }
                    subject := add(subject, w) // `sub(subject, 1)`.
                    if iszero(gt(subject, end)) { break }
                }
                break
            }
        }
    }

    /// @dev Returns the byte index of the first location of `needle` in `subject`,
    /// needleing from right to left.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `needle` is not found.
    function lastIndexOf(string memory subject, string memory needle)
        internal
        pure
        returns (uint256 result)
    {
        result = lastIndexOf(subject, needle, type(uint256).max);
    }

    /// @dev Returns true if `needle` is found in `subject`, false otherwise.
    function contains(string memory subject, string memory needle) internal pure returns (bool) {
        return indexOf(subject, needle) != NOT_FOUND;
    }

    /// @dev Returns whether `subject` starts with `needle`.
    function startsWith(string memory subject, string memory needle)
        internal
        pure
        returns (bool result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let needleLen := mload(needle)
            // Just using keccak256 directly is actually cheaper.
            // forgefmt: disable-next-item
            result := and(
                iszero(gt(needleLen, mload(subject))),
                eq(
                    keccak256(add(subject, 0x20), needleLen),
                    keccak256(add(needle, 0x20), needleLen)
                )
            )
        }
    }

    /// @dev Returns whether `subject` ends with `needle`.
    function endsWith(string memory subject, string memory needle)
        internal
        pure
        returns (bool result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let needleLen := mload(needle)
            // Whether `needle` is not longer than `subject`.
            let inRange := iszero(gt(needleLen, mload(subject)))
            // Just using keccak256 directly is actually cheaper.
            // forgefmt: disable-next-item
            result := and(
                eq(
                    keccak256(
                        // `subject + 0x20 + max(subjectLen - needleLen, 0)`.
                        add(add(subject, 0x20), mul(inRange, sub(mload(subject), needleLen))),
                        needleLen
                    ),
                    keccak256(add(needle, 0x20), needleLen)
                ),
                inRange
            )
        }
    }

    /// @dev Returns `subject` repeated `times`.
    function repeat(string memory subject, uint256 times)
        internal
        pure
        returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let subjectLen := mload(subject)
            if iszero(or(iszero(times), iszero(subjectLen))) {
                result := mload(0x40)
                subject := add(subject, 0x20)
                let o := add(result, 0x20)
                for {} 1 {} {
                    // Copy the `subject` one word at a time.
                    for { let j := 0 } 1 {} {
                        mstore(add(o, j), mload(add(subject, j)))
                        j := add(j, 0x20)
                        if iszero(lt(j, subjectLen)) { break }
                    }
                    o := add(o, subjectLen)
                    times := sub(times, 1)
                    if iszero(times) { break }
                }
                mstore(o, 0) // Zeroize the slot after the string.
                mstore(0x40, add(o, 0x20)) // Allocate memory.
                mstore(result, sub(o, add(result, 0x20))) // Store the length.
            }
        }
    }

    /// @dev Returns a copy of `subject` sliced from `start` to `end` (exclusive).
    /// `start` and `end` are byte offsets.
    function slice(string memory subject, uint256 start, uint256 end)
        internal
        pure
        returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let subjectLen := mload(subject)
            if iszero(gt(subjectLen, end)) { end := subjectLen }
            if iszero(gt(subjectLen, start)) { start := subjectLen }
            if lt(start, end) {
                result := mload(0x40)
                let n := sub(end, start)
                let i := add(subject, start)
                let w := not(0x1f)
                // Copy the `subject` one word at a time, backwards.
                for { let j := and(add(n, 0x1f), w) } 1 {} {
                    mstore(add(result, j), mload(add(i, j)))
                    j := add(j, w) // `sub(j, 0x20)`.
                    if iszero(j) { break }
                }
                let o := add(add(result, 0x20), n)
                mstore(o, 0) // Zeroize the slot after the string.
                mstore(0x40, add(o, 0x20)) // Allocate memory.
                mstore(result, n) // Store the length.
            }
        }
    }

    /// @dev Returns a copy of `subject` sliced from `start` to the end of the string.
    /// `start` is a byte offset.
    function slice(string memory subject, uint256 start)
        internal
        pure
        returns (string memory result)
    {
        result = slice(subject, start, type(uint256).max);
    }

    /// @dev Returns all the indices of `needle` in `subject`.
    /// The indices are byte offsets.
    function indicesOf(string memory subject, string memory needle)
        internal
        pure
        returns (uint256[] memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let searchLen := mload(needle)
            if iszero(gt(searchLen, mload(subject))) {
                result := mload(0x40)
                let i := add(subject, 0x20)
                let o := add(result, 0x20)
                let subjectSearchEnd := add(sub(add(i, mload(subject)), searchLen), 1)
                let h := 0 // The hash of `needle`.
                if iszero(lt(searchLen, 0x20)) { h := keccak256(add(needle, 0x20), searchLen) }
                let s := mload(add(needle, 0x20))
                for { let m := shl(3, sub(0x20, and(searchLen, 0x1f))) } 1 {} {
                    let t := mload(i)
                    // Whether the first `searchLen % 32` bytes of `subject` and `needle` matches.
                    if iszero(shr(m, xor(t, s))) {
                        if h {
                            if iszero(eq(keccak256(i, searchLen), h)) {
                                i := add(i, 1)
                                if iszero(lt(i, subjectSearchEnd)) { break }
                                continue
                            }
                        }
                        mstore(o, sub(i, add(subject, 0x20))) // Append to `result`.
                        o := add(o, 0x20)
                        i := add(i, searchLen) // Advance `i` by `searchLen`.
                        if searchLen {
                            if iszero(lt(i, subjectSearchEnd)) { break }
                            continue
                        }
                    }
                    i := add(i, 1)
                    if iszero(lt(i, subjectSearchEnd)) { break }
                }
                mstore(result, shr(5, sub(o, add(result, 0x20)))) // Store the length of `result`.
                // Allocate memory for result.
                // We allocate one more word, so this array can be recycled for {split}.
                mstore(0x40, add(o, 0x20))
            }
        }
    }

    /// @dev Returns a arrays of strings based on the `delimiter` inside of the `subject` string.
    function split(string memory subject, string memory delimiter)
        internal
        pure
        returns (string[] memory result)
    {
        uint256[] memory indices = indicesOf(subject, delimiter);
        /// @solidity memory-safe-assembly
        assembly {
            let w := not(0x1f)
            let indexPtr := add(indices, 0x20)
            let indicesEnd := add(indexPtr, shl(5, add(mload(indices), 1)))
            mstore(add(indicesEnd, w), mload(subject))
            mstore(indices, add(mload(indices), 1))
            for { let prevIndex := 0 } 1 {} {
                let index := mload(indexPtr)
                mstore(indexPtr, 0x60)
                if iszero(eq(index, prevIndex)) {
                    let element := mload(0x40)
                    let l := sub(index, prevIndex)
                    mstore(element, l) // Store the length of the element.
                    // Copy the `subject` one word at a time, backwards.
                    for { let o := and(add(l, 0x1f), w) } 1 {} {
                        mstore(add(element, o), mload(add(add(subject, prevIndex), o)))
                        o := add(o, w) // `sub(o, 0x20)`.
                        if iszero(o) { break }
                    }
                    mstore(add(add(element, 0x20), l), 0) // Zeroize the slot after the string.
                    // Allocate memory for the length and the bytes, rounded up to a multiple of 32.
                    mstore(0x40, add(element, and(add(l, 0x3f), w)))
                    mstore(indexPtr, element) // Store the `element` into the array.
                }
                prevIndex := add(index, mload(delimiter))
                indexPtr := add(indexPtr, 0x20)
                if iszero(lt(indexPtr, indicesEnd)) { break }
            }
            result := indices
            if iszero(mload(delimiter)) {
                result := add(indices, 0x20)
                mstore(result, sub(mload(indices), 2))
            }
        }
    }

    /// @dev Returns a concatenated string of `a` and `b`.
    /// Cheaper than `string.concat()` and does not de-align the free memory pointer.
    function concat(string memory a, string memory b)
        internal
        pure
        returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            let w := not(0x1f)
            let aLen := mload(a)
            // Copy `a` one word at a time, backwards.
            for { let o := and(add(aLen, 0x20), w) } 1 {} {
                mstore(add(result, o), mload(add(a, o)))
                o := add(o, w) // `sub(o, 0x20)`.
                if iszero(o) { break }
            }
            let bLen := mload(b)
            let output := add(result, aLen)
            // Copy `b` one word at a time, backwards.
            for { let o := and(add(bLen, 0x20), w) } 1 {} {
                mstore(add(output, o), mload(add(b, o)))
                o := add(o, w) // `sub(o, 0x20)`.
                if iszero(o) { break }
            }
            let totalLen := add(aLen, bLen)
            let last := add(add(result, 0x20), totalLen)
            mstore(last, 0) // Zeroize the slot after the string.
            mstore(result, totalLen) // Store the length.
            mstore(0x40, add(last, 0x20)) // Allocate memory.
        }
    }

    /// @dev Returns a copy of the string in either lowercase or UPPERCASE.
    /// WARNING! This function is only compatible with 7-bit ASCII strings.
    function toCase(string memory subject, bool toUpper)
        internal
        pure
        returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let n := mload(subject)
            if n {
                result := mload(0x40)
                let o := add(result, 0x20)
                let d := sub(subject, result)
                let flags := shl(add(70, shl(5, toUpper)), 0x3ffffff)
                for { let end := add(o, n) } 1 {} {
                    let b := byte(0, mload(add(d, o)))
                    mstore8(o, xor(and(shr(b, flags), 0x20), b))
                    o := add(o, 1)
                    if eq(o, end) { break }
                }
                mstore(result, n) // Store the length.
                mstore(o, 0) // Zeroize the slot after the string.
                mstore(0x40, add(o, 0x20)) // Allocate memory.
            }
        }
    }

    /// @dev Returns a string from a small bytes32 string.
    /// `s` must be null-terminated, or behavior will be undefined.
    function fromSmallString(bytes32 s) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            let n := 0
            for {} byte(n, s) { n := add(n, 1) } {} // Scan for '\0'.
            mstore(result, n) // Store the length.
            let o := add(result, 0x20)
            mstore(o, s) // Store the bytes of the string.
            mstore(add(o, n), 0) // Zeroize the slot after the string.
            mstore(0x40, add(result, 0x40)) // Allocate memory.
        }
    }

    /// @dev Returns the small string, with all bytes after the first null byte zeroized.
    function normalizeSmallString(bytes32 s) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            for {} byte(result, s) { result := add(result, 1) } {} // Scan for '\0'.
            mstore(0x00, s)
            mstore(result, 0x00)
            result := mload(0x00)
        }
    }

    /// @dev Returns the string as a normalized null-terminated small string.
    function toSmallString(string memory s) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(s)
            if iszero(lt(result, 33)) {
                mstore(0x00, 0xec92f9a3) // `TooBigForSmallString()`.
                revert(0x1c, 0x04)
            }
            result := shl(shl(3, sub(32, result)), mload(add(s, result)))
        }
    }

    /// @dev Returns a lowercased copy of the string.
    /// WARNING! This function is only compatible with 7-bit ASCII strings.
    function lower(string memory subject) internal pure returns (string memory result) {
        result = toCase(subject, false);
    }

    /// @dev Returns an UPPERCASED copy of the string.
    /// WARNING! This function is only compatible with 7-bit ASCII strings.
    function upper(string memory subject) internal pure returns (string memory result) {
        result = toCase(subject, true);
    }

    /// @dev Escapes the string to be used within HTML tags.
    function escapeHTML(string memory s) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            let end := add(s, mload(s))
            let o := add(result, 0x20)
            // Store the bytes of the packed offsets and strides into the scratch space.
            // `packed = (stride << 5) | offset`. Max offset is 20. Max stride is 6.
            mstore(0x1f, 0x900094)
            mstore(0x08, 0xc0000000a6ab)
            // Store "&quot;&amp;&#39;&lt;&gt;" into the scratch space.
            mstore(0x00, shl(64, 0x2671756f743b26616d703b262333393b266c743b2667743b))
            for {} iszero(eq(s, end)) {} {
                s := add(s, 1)
                let c := and(mload(s), 0xff)
                // Not in `["\"","'","&","<",">"]`.
                if iszero(and(shl(c, 1), 0x500000c400000000)) {
                    mstore8(o, c)
                    o := add(o, 1)
                    continue
                }
                let t := shr(248, mload(c))
                mstore(o, mload(and(t, 0x1f)))
                o := add(o, shr(5, t))
            }
            mstore(o, 0) // Zeroize the slot after the string.
            mstore(result, sub(o, add(result, 0x20))) // Store the length.
            mstore(0x40, add(o, 0x20)) // Allocate memory.
        }
    }

    /// @dev Escapes the string to be used within double-quotes in a JSON.
    /// If `addDoubleQuotes` is true, the result will be enclosed in double-quotes.
    function escapeJSON(string memory s, bool addDoubleQuotes)
        internal
        pure
        returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            let o := add(result, 0x20)
            if addDoubleQuotes {
                mstore8(o, 34)
                o := add(1, o)
            }
            // Store "\\u0000" in scratch space.
            // Store "0123456789abcdef" in scratch space.
            // Also, store `{0x08:"b", 0x09:"t", 0x0a:"n", 0x0c:"f", 0x0d:"r"}`.
            // into the scratch space.
            mstore(0x15, 0x5c75303030303031323334353637383961626364656662746e006672)
            // Bitmask for detecting `["\"","\\"]`.
            let e := or(shl(0x22, 1), shl(0x5c, 1))
            for { let end := add(s, mload(s)) } iszero(eq(s, end)) {} {
                s := add(s, 1)
                let c := and(mload(s), 0xff)
                if iszero(lt(c, 0x20)) {
                    if iszero(and(shl(c, 1), e)) {
                        // Not in `["\"","\\"]`.
                        mstore8(o, c)
                        o := add(o, 1)
                        continue
                    }
                    mstore8(o, 0x5c) // "\\".
                    mstore8(add(o, 1), c)
                    o := add(o, 2)
                    continue
                }
                if iszero(and(shl(c, 1), 0x3700)) {
                    // Not in `["\b","\t","\n","\f","\d"]`.
                    mstore8(0x1d, mload(shr(4, c))) // Hex value.
                    mstore8(0x1e, mload(and(c, 15))) // Hex value.
                    mstore(o, mload(0x19)) // "\\u00XX".
                    o := add(o, 6)
                    continue
                }
                mstore8(o, 0x5c) // "\\".
                mstore8(add(o, 1), mload(add(c, 8)))
                o := add(o, 2)
            }
            if addDoubleQuotes {
                mstore8(o, 34)
                o := add(1, o)
            }
            mstore(o, 0) // Zeroize the slot after the string.
            mstore(result, sub(o, add(result, 0x20))) // Store the length.
            mstore(0x40, add(o, 0x20)) // Allocate memory.
        }
    }

    /// @dev Escapes the string to be used within double-quotes in a JSON.
    function escapeJSON(string memory s) internal pure returns (string memory result) {
        result = escapeJSON(s, false);
    }

    /// @dev Encodes `s` so that it can be safely used in a URI,
    /// just like `encodeURIComponent` in JavaScript.
    /// See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent
    /// See: https://datatracker.ietf.org/doc/html/rfc2396
    /// See: https://datatracker.ietf.org/doc/html/rfc3986
    function encodeURIComponent(string memory s) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            // Store "0123456789ABCDEF" in scratch space.
            // Uppercased to be consistent with JavaScript's implementation.
            mstore(0x0f, 0x30313233343536373839414243444546)
            let o := add(result, 0x20)
            for { let end := add(s, mload(s)) } iszero(eq(s, end)) {} {
                s := add(s, 1)
                let c := and(mload(s), 0xff)
                // If not in `[0-9A-Z-a-z-.!~*'()]`.
                if iszero(and(1, shr(c, 0x47fffffe07fffffe03ff678200000000))) {
                    mstore8(o, 0x25) // '%'.
                    mstore8(add(o, 1), mload(and(shr(4, c), 15)))
                    mstore8(add(o, 2), mload(and(c, 15)))
                    o := add(o, 3)
                    continue
                }
                mstore8(o, c)
                o := add(o, 1)
            }
            mstore(result, sub(o, add(result, 0x20))) // Store the length.
            mstore(o, 0) // Zeroize the slot after the string.
            mstore(0x40, add(o, 0x20)) // Allocate memory.
        }
    }

    /// @dev Returns whether `a` equals `b`.
    function eq(string memory a, string memory b) internal pure returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := eq(keccak256(add(a, 0x20), mload(a)), keccak256(add(b, 0x20), mload(b)))
        }
    }

    /// @dev Returns whether `a` equals `b`, where `b` is a null-terminated small string.
    function eqs(string memory a, bytes32 b) internal pure returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            // These should be evaluated on compile time, as far as possible.
            let m := not(shl(7, div(not(iszero(b)), 255))) // `0x7f7f ...`.
            let x := not(or(m, or(b, add(m, and(b, m)))))
            let r := shl(7, iszero(iszero(shr(128, x))))
            r := or(r, shl(6, iszero(iszero(shr(64, shr(r, x))))))
            r := or(r, shl(5, lt(0xffffffff, shr(r, x))))
            r := or(r, shl(4, lt(0xffff, shr(r, x))))
            r := or(r, shl(3, lt(0xff, shr(r, x))))
            // forgefmt: disable-next-item
            result := gt(eq(mload(a), add(iszero(x), xor(31, shr(3, r)))),
                xor(shr(add(8, r), b), shr(add(8, r), mload(add(a, 0x20)))))
        }
    }

    /// @dev Packs a single string with its length into a single word.
    /// Returns `bytes32(0)` if the length is zero or greater than 31.
    function packOne(string memory a) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            // We don't need to zero right pad the string,
            // since this is our own custom non-standard packing scheme.
            result :=
                mul(
                    // Load the length and the bytes.
                    mload(add(a, 0x1f)),
                    // `length != 0 && length < 32`. Abuses underflow.
                    // Assumes that the length is valid and within the block gas limit.
                    lt(sub(mload(a), 1), 0x1f)
                )
        }
    }

    /// @dev Unpacks a string packed using {packOne}.
    /// Returns the empty string if `packed` is `bytes32(0)`.
    /// If `packed` is not an output of {packOne}, the output behavior is undefined.
    function unpackOne(bytes32 packed) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40) // Grab the free memory pointer.
            mstore(0x40, add(result, 0x40)) // Allocate 2 words (1 for the length, 1 for the bytes).
            mstore(result, 0) // Zeroize the length slot.
            mstore(add(result, 0x1f), packed) // Store the length and bytes.
            mstore(add(add(result, 0x20), mload(result)), 0) // Right pad with zeroes.
        }
    }

    /// @dev Packs two strings with their lengths into a single word.
    /// Returns `bytes32(0)` if combined length is zero or greater than 30.
    function packTwo(string memory a, string memory b) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            let aLen := mload(a)
            // We don't need to zero right pad the strings,
            // since this is our own custom non-standard packing scheme.
            result :=
                mul(
                    or( // Load the length and the bytes of `a` and `b`.
                    shl(shl(3, sub(0x1f, aLen)), mload(add(a, aLen))), mload(sub(add(b, 0x1e), aLen))),
                    // `totalLen != 0 && totalLen < 31`. Abuses underflow.
                    // Assumes that the lengths are valid and within the block gas limit.
                    lt(sub(add(aLen, mload(b)), 1), 0x1e)
                )
        }
    }

    /// @dev Unpacks strings packed using {packTwo}.
    /// Returns the empty strings if `packed` is `bytes32(0)`.
    /// If `packed` is not an output of {packTwo}, the output behavior is undefined.
    function unpackTwo(bytes32 packed)
        internal
        pure
        returns (string memory resultA, string memory resultB)
    {
        /// @solidity memory-safe-assembly
        assembly {
            resultA := mload(0x40) // Grab the free memory pointer.
            resultB := add(resultA, 0x40)
            // Allocate 2 words for each string (1 for the length, 1 for the byte). Total 4 words.
            mstore(0x40, add(resultB, 0x40))
            // Zeroize the length slots.
            mstore(resultA, 0)
            mstore(resultB, 0)
            // Store the lengths and bytes.
            mstore(add(resultA, 0x1f), packed)
            mstore(add(resultB, 0x1f), mload(add(add(resultA, 0x20), mload(resultA))))
            // Right pad with zeroes.
            mstore(add(add(resultA, 0x20), mload(resultA)), 0)
            mstore(add(add(resultB, 0x20), mload(resultB)), 0)
        }
    }

    /// @dev Directly returns `a` without copying.
    function directReturn(string memory a) internal pure {
        assembly {
            // Assumes that the string does not start from the scratch space.
            let retStart := sub(a, 0x20)
            let retUnpaddedSize := add(mload(a), 0x40)
            // Right pad with zeroes. Just in case the string is produced
            // by a method that doesn't zero right pad.
            mstore(add(retStart, retUnpaddedSize), 0)
            mstore(retStart, 0x20) // Store the return offset.
            // End the transaction, returning the string.
            return(retStart, and(not(0x1f), add(0x1f, retUnpaddedSize)))
        }
    }
}

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