// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: @openzeppelin/contracts/interfaces/IERC165.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (interfaces/IERC165.sol)

pragma solidity ^0.8.0;

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;

import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/Address.sol";
import "../../utils/Context.sol";
import "../../utils/Strings.sol";
import "../../utils/introspection/ERC165.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}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping(address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

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

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

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: address zero is not a valid owner");
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _ownerOf(tokenId);
        require(owner != address(0), "ERC721: invalid token ID");
        return owner;
    }

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

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

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

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

    /**
     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
     * by default, can be overridden in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not token owner or approved for all"
        );

        _approve(to, tokenId);
    }

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

        return _tokenApprovals[tokenId];
    }

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

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

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner or approved");

        _transfer(from, to, tokenId);
    }

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

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes memory data
    ) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner or approved");
        _safeTransfer(from, to, tokenId, data);
    }

    /**
     * @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.
     *
     * `data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(
        address from,
        address to,
        uint256 tokenId,
        bytes memory data
    ) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns the owner of the `tokenId`. Does NOT revert if token doesn't exist
     */
    function _ownerOf(uint256 tokenId) internal view virtual returns (address) {
        return _owners[tokenId];
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _ownerOf(tokenId) != address(0);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || isApprovedForAll(owner, spender) || getApproved(tokenId) == spender);
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _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);
        require(
            _checkOnERC721Received(address(0), to, tokenId, data),
            "ERC721: transfer to non ERC721Receiver implementer"
        );
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId, 1);

        // Check that tokenId was not minted by `_beforeTokenTransfer` hook
        require(!_exists(tokenId), "ERC721: token already minted");

        unchecked {
            // Will not overflow unless all 2**256 token ids are minted to the same owner.
            // Given that tokens are minted one by one, it is impossible in practice that
            // this ever happens. Might change if we allow batch minting.
            // The ERC fails to describe this case.
            _balances[to] += 1;
        }

        _owners[tokenId] = to;

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

        _afterTokenTransfer(address(0), to, tokenId, 1);
    }

    /**
     * @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 virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId, 1);

        // Update ownership in case tokenId was transferred by `_beforeTokenTransfer` hook
        owner = ERC721.ownerOf(tokenId);

        // Clear approvals
        delete _tokenApprovals[tokenId];

        unchecked {
            // Cannot overflow, as that would require more tokens to be burned/transferred
            // out than the owner initially received through minting and transferring in.
            _balances[owner] -= 1;
        }
        delete _owners[tokenId];

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

        _afterTokenTransfer(owner, address(0), tokenId, 1);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId, 1);

        // Check that tokenId was not transferred by `_beforeTokenTransfer` hook
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");

        // Clear approvals from the previous owner
        delete _tokenApprovals[tokenId];

        unchecked {
            // `_balances[from]` cannot overflow for the same reason as described in `_burn`:
            // `from`'s balance is the number of token held, which is at least one before the current
            // transfer.
            // `_balances[to]` could overflow in the conditions described in `_mint`. That would require
            // all 2**256 token ids to be minted, which in practice is impossible.
            _balances[from] -= 1;
            _balances[to] += 1;
        }
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);

        _afterTokenTransfer(from, to, tokenId, 1);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits an {Approval} event.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
    }

    /**
     * @dev Approve `operator` to operate on all of `owner` tokens
     *
     * Emits an {ApprovalForAll} event.
     */
    function _setApprovalForAll(
        address owner,
        address operator,
        bool approved
    ) internal virtual {
        require(owner != operator, "ERC721: approve to caller");
        _operatorApprovals[owner][operator] = approved;
        emit ApprovalForAll(owner, operator, approved);
    }

    /**
     * @dev Reverts if the `tokenId` has not been minted yet.
     */
    function _requireMinted(uint256 tokenId) internal view virtual {
        require(_exists(tokenId), "ERC721: invalid token ID");
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory data
    ) private returns (bool) {
        if (to.isContract()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, data) returns (bytes4 retval) {
                return retval == IERC721Receiver.onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    /// @solidity memory-safe-assembly
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting and burning. If {ERC721Consecutive} is
     * used, the hook may be called as part of a consecutive (batch) mint, as indicated by `batchSize` greater than 1.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s tokens will be transferred to `to`.
     * - When `from` is zero, the tokens will be minted for `to`.
     * - When `to` is zero, ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     * - `batchSize` is non-zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256, /* firstTokenId */
        uint256 batchSize
    ) internal virtual {
        if (batchSize > 1) {
            if (from != address(0)) {
                _balances[from] -= batchSize;
            }
            if (to != address(0)) {
                _balances[to] += batchSize;
            }
        }
    }

    /**
     * @dev Hook that is called after any token transfer. This includes minting and burning. If {ERC721Consecutive} is
     * used, the hook may be called as part of a consecutive (batch) mint, as indicated by `batchSize` greater than 1.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s tokens were transferred to `to`.
     * - When `from` is zero, the tokens were minted for `to`.
     * - When `to` is zero, ``from``'s tokens were burned.
     * - `from` and `to` are never both zero.
     * - `batchSize` is non-zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 firstTokenId,
        uint256 batchSize
    ) internal virtual {}
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

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

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

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

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

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

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

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * 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 caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

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

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

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



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

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)

pragma solidity ^0.8.1;

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

        return account.code.length > 0;
    }

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

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

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

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

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

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

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

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

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

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

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



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

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

import "./math/Math.sol";

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

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        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), _SYMBOLS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @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) {
        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] = _SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }
}

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



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

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: @openzeppelin/contracts/utils/math/Math.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    enum Rounding {
        Down, // Toward negative infinity
        Up, // Toward infinity
        Zero // Toward zero
    }

    /**
     * @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 up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (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; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod0 := mul(x, y)
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            require(denominator > prod1);

            ///////////////////////////////////////////////
            // 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.

            // Does not overflow because the denominator cannot be zero at this stage in the function.
            uint256 twos = denominator & (~denominator + 1);
            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 (rounding == Rounding.Up && 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 down.
     *
     * 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 + (rounding == Rounding.Up && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2, rounded down, of a positive value.
     * 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 + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10, rounded down, of a positive value.
     * 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 + (rounding == Rounding.Up && 10**result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256, rounded down, of a positive value.
     * 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 10, 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 + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);
        }
    }
}

// File: contracts/BlackHolesV2.sol



// SPDX-License-Identifier: MIT
/*                                                                                                                                                                                                                                          
                                                         ........................                                                           
                                                   .....*22222222222222222222222#......                                                     
                                                  ,*****(222222222222222222222222******                                                     
                                                ../22222244444444444444444444444422222#...                                                  
                                             ..*22222244(                       .444222222...                                               
                                          ../22244444(                              44444422#...                                            
                                       ../22222244/                                   .444222222...                                         
                                       ../22244/                                          444222...                                         
                                      .,,(22###*                                          ###222,,,                                         
                                    ../22244*                                                444222...                                      
                                    ../22244*                                                444222...                                      
                                    ../22244*                                                444222...                                      
                                   .../22244*                                                444222...                                      
                                 ../((#22244*                                                444222(((...                                   
                                ...(22222244*                                                44422222#...                                   
                             ...(22222244444/...............................................,444444222222...                                
                             #444444444444444444444444444444444444444444444444444444444444444444444444444442                                
                                 ................./22222222222222222222222222222222222#..................                                   
                                       ../22244/            ..................            444222...                                         
                                       ../22222(**.                                    ***222222...                                         
                                       ../22222244/                                   .444222222...                                         
                                          ../22244444(                              44444422#...                                            
                                          .....*22222244(                       .444222222...                                               
                                                ../22222244444444444444444444444422222#...                                                  
                                                   .....*22222222222222222222222#......                                                     
                                                   .....*#######################(......                                                     
                                                         ........................                                                           
                                                                                  
                                                                          ,----,   
                                                              ,---.    .'   .' \  
                                                              /__./|  ,----,'    | 
                                                        ,---.;  ; |  |    :  .  ; 
                                                        /___/ \  | |  ;    |.'  /  
                                                        \   ;  \ ' |  `----'/  ;   
                                                        \   \  \: |    /  ;  /    
                                                          ;   \  ' .   ;  /  /-,   
                                                          \   \   '  /  /  /.`|   
                                                            \   `  ;./__;      :   
                                                            :   \ ||   :    .'    
                                                              '---" ;   | .'       
                                                                    `---'          
                                                                                  
*/

pragma solidity ^0.8.12;

import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {ERC4906} from "./interfaces/ERC4906.sol";
import "./Utilities.sol";
import "./interfaces/IRenderer.sol";
import "./interfaces/BlackHole.sol";
import "svgnft/contracts/Base64.sol";
import "./interfaces/IBlackHoles.sol";

contract BlackHolesV2 is ERC4906, Ownable {
  error NotAllowed();
  error URIQueryForNonexistentToken();
  error NotBlackHolesContract();

  uint256 public mergeOpenTimestamp;

  mapping(uint256 => uint256) public massesConsumed;

  IRenderer public renderer;
  IBlackHoles public unmigratedBlackHoles;
  IBlackHoles public voidableBlackHoles;

  uint256 minted;
  uint256 burned;

  /**
   * @dev Constructs a new instance of the contract.
   * @param _name Name of the ERC721 token.
   * @param _symbol Symbol of the ERC721 token.
   * @param _mergeOpenTimestamp Timestamp when merging is open.
   * @param _renderer Address of the Renderer contract.
   * @param _unmigratedBlackHoles Address of Black Holes contract.
   */
  constructor(
    string memory _name,
    string memory _symbol,
    uint256 _mergeOpenTimestamp,
    address _renderer,
    address _unmigratedBlackHoles,
    address _voidableBlackHoles
  ) ERC4906(_name, _symbol) {
    mergeOpenTimestamp = _mergeOpenTimestamp;
    renderer = IRenderer(_renderer);
    unmigratedBlackHoles = IBlackHoles(_unmigratedBlackHoles);
    voidableBlackHoles = IBlackHoles(_voidableBlackHoles);
  }

  /**
   * @notice Sets the merging delay.
   * @param _mergeOpenTimestamp Timestamp when merging is open.
   */
  function setMergeOpenTimestamp(uint256 _mergeOpenTimestamp) external onlyOwner {
    mergeOpenTimestamp = _mergeOpenTimestamp;
  }

  /**
   * @notice Returns the token URI for a given token ID.
   * @param _tokenId ID of the token to get the URI for.
   * @return Token URI.
   */
  function tokenURI(uint256 _tokenId) public view virtual override returns (string memory) {
    if (!_exists(_tokenId)) revert URIQueryForNonexistentToken();

    string memory name = string(abi.encodePacked("BlackHole #", utils.uint2str(_tokenId)));
    string
      memory description = "Fully on-chain, procedurally generated, animated black holes. Beyond the event horizon.";

    BlackHole memory blackHole = blackHoleForTokenId(_tokenId);

    string memory svg = renderer.getBlackHoleSVG(blackHole);

    string memory attributes = string.concat(
      "[",
      '{"trait_type": "Level", "value": ',
      utils.uint2str(blackHole.level),
      "},",
      '{"trait_type": "Name", "value": "',
      blackHole.name,
      '"},',
      '{"trait_type": "Mass", "value": ',
      utils.uint2str(blackHole.mass),
      "}]"
    );

    string memory json = string(
      abi.encodePacked(
        '{"name":"',
        name,
        '","description":"',
        description,
        '",',
        '"attributes": ',
        attributes, // attributes
        ', "image": "data:image/svg+xml;base64,',
        Base64.encode(bytes(svg)),
        '"}'
      )
    );
    return string(abi.encodePacked("data:application/json;base64,", Base64.encode(bytes(json))));
  }

  /**
   * @notice Get the structured representation of a token by its ID.
   * @param _tokenId ID of the token.
   * @return BlackHole Structured representation of the token.
   */
  function blackHoleForTokenId(uint256 _tokenId) public view returns (BlackHole memory) {
    uint256 mass = massForTokenId(_tokenId);
    uint256 level = levelForMass(mass);
    string memory name = nameForBlackHoleLevel(level);
    uint256 adjustment = getAdjustmentForMass(mass);

    return
      BlackHole({
        tokenId: _tokenId,
        level: level,
        size: renderer.PIXELS_PER_SIDE() / 2 - (10 - level),
        mass: mass,
        name: name,
        adjustment: adjustment
      });
  }

  /**
   * @notice Gets adjustment for a given mass.
   * @param _mass Mass to calculate the adjustment for.
   * @return Adjustment.
   */
  function getAdjustmentForMass(uint256 _mass) public view returns (uint256) {
    uint256 level = levelForMass(_mass); // 1

    if (level == unmigratedBlackHoles.MAX_LEVEL()) {
      return 0;
    }

    int256 maxAdjustment = 20;
    int256 adjustment = 0;
    uint256[] memory upgradeIntervals = getUpgradeIntervals();

    if (level == 0) {
      adjustment = (-maxAdjustment * int256(_mass - 1)) / int256(upgradeIntervals[0] - 2) + maxAdjustment;
    } else {
      adjustment =
        (-maxAdjustment * int256(_mass - upgradeIntervals[level - 1])) /
        int256(upgradeIntervals[level] - upgradeIntervals[level - 1] - 1) +
        maxAdjustment;
    }

    return uint256(adjustment);
  }

  /**
   * @notice Gets the level for a given mass.
   */
  function levelForMass(uint256 _mass) public view returns (uint256) {
    uint256[] memory upgradeIntervals = getUpgradeIntervals();

    if (_mass < upgradeIntervals[0]) {
      return 0;
    } else if (_mass < upgradeIntervals[1]) {
      return 1;
    } else if (_mass < upgradeIntervals[2]) {
      return 2;
    } else if (_mass < upgradeIntervals[3]) {
      return 3;
    } else {
      return 4;
    }
  }

  function massForTokenId(uint256 _tokenId) public view returns (uint256) {
    return massesConsumed[_tokenId] + 1;
  }

  /**
   * @notice Returns the mass required to upgrade to the next level for each level.
   */
  function getUpgradeIntervals() public view returns (uint256[] memory) {
    uint256 baseUpgradeMass = utils.max(
      unmigratedBlackHoles.totalMinted() /
        unmigratedBlackHoles.MAX_SUPPLY_OF_INTERSTELLAR() /
        2**(unmigratedBlackHoles.MAX_LEVEL() - 1),
      2
    );
    uint256[] memory intervals = new uint256[](unmigratedBlackHoles.MAX_LEVEL() + 1);
    intervals[0] = 5;
    intervals[1] = baseUpgradeMass * 2;
    intervals[2] = baseUpgradeMass * 3;
    intervals[3] = baseUpgradeMass * 8;
    return intervals;
  }

  /**
   * @notice Returns the name of a black hole level.
   * @param _level Level of the black hole.
   * @return name of the black hole level.
   */
  function nameForBlackHoleLevel(uint256 _level) public view returns (string memory) {
    return unmigratedBlackHoles.nameForBlackHoleLevel(_level);
  }

  /**
   * @notice Migrate Black Holes to Voidable Black Holes by burning the Black Holes.
   *         Requires the Approval of this contract on the Edition contract.
   * @param tokenIds The Edition token IDs you want to migrate.
   */
  function migrate(IBlackHoles blackHoles, uint256[] memory tokenIds) public {
    if (!(address(blackHoles) == address(unmigratedBlackHoles) || address(blackHoles) == address(voidableBlackHoles))) {
      revert NotBlackHolesContract();
    }

    uint256 count = tokenIds.length;

    // Burn the Black Holes for the given tokenIds & mint the Voidable Black Holes.
    for (uint256 i; i < count; ) {
      uint256 id = tokenIds[i];
      address owner = blackHoles.ownerOf(id);

      // Check whether we're allowed to migrate this Black Hole.
      if (
        owner != msg.sender &&
        (!blackHoles.isApprovedForAll(owner, msg.sender)) &&
        blackHoles.getApproved(id) != msg.sender
      ) {
        revert NotAllowed();
      }

      // Copy mass.
      massesConsumed[id] = blackHoles.massForTokenId(id) - 1;

      // Burn old.
      blackHoles.transferFrom(owner, address(1), id);

      // Mint new.
      _safeMint(msg.sender, id);

      unchecked {
        ++i;
      }
    }

    // Keep track of how many checks have been minted.
    minted += count;
  }

  /**
   * @notice Returns whether merging is enabled or not.
   */
  function isMergingEnabled() public view returns (bool) {
    return block.timestamp > mergeOpenTimestamp;
  }

  /**
   * @notice Simulates the merge for an array of tokens.
   * @param totalMass mass of tokens to merge.
   * @return BlackHole struct of new Black Hole.
   * @return SVG of new Black Hole.
   */
  function blackHoleForMass(uint256 targetId, uint256 totalMass) public view returns (BlackHole memory, string memory) {
    uint256 mass = totalMass;
    uint256 level = levelForMass(mass);
    string memory name = nameForBlackHoleLevel(level);
    uint256 adjustment = getAdjustmentForMass(mass);

    BlackHole memory blackHole = BlackHole({
      tokenId: targetId,
      level: level,
      size: renderer.PIXELS_PER_SIDE() / 2 - (10 - level),
      mass: mass,
      name: name,
      adjustment: adjustment
    });

    return (blackHole, renderer.getBlackHoleSVG(blackHole));
  }

  /**
   * @notice Merges a list of tokens into a single token.
   * @param tokens List of token IDs to merge. The first token in the list is the target.
   */
  function merge(uint256[] memory tokens) public {
    // Burn all tokens except the first one, aka the target
    // The mass of all other tokens get added to the target
    require(isMergingEnabled(), "Merging not enabled");
    require(tokens.length > 1, "Must merge at least 2 tokens");

    uint256 targetId = tokens[0];

    require(ownerOf(tokens[0]) == msg.sender, "Must own all tokens (target)");

    uint256 sum;
    for (uint256 i = 1; i < tokens.length; ) {
      require(ownerOf(tokens[i]) == msg.sender, "Must own all tokens (burn)");
      sum = sum + massForTokenId(tokens[i]);
      _burn(tokens[i]);

      unchecked {
        ++i;
      }
    }

    burned += uint32(tokens.length - 1);

    massesConsumed[targetId] += sum;

    emit MetadataUpdate(targetId);
  }

  /**
   * @notice Returns Black Holes for a list of token IDs.
   * @param tokenIds List of token IDs.
   */
  function blackHolesForTokenIds(uint256[] memory tokenIds) public view returns (BlackHole[] memory) {
    BlackHole[] memory blackHoles = new BlackHole[](tokenIds.length);
    for (uint256 i = 0; i < tokenIds.length; i++) {
      blackHoles[i] = blackHoleForTokenId(tokenIds[i]);
    }
    return blackHoles;
  }

  /**
   * @notice Returns total number of tokens minted.
   */
  function totalMinted() external view returns (uint256) {
    return minted;
  }

  /**
   * @notice Returns total number of tokens burned.
   */
  function totalBurned() external view returns (uint256) {
    return burned;
  }

  /**
   * @notice Returns how many tokens this contract manages.
   */
  function totalSupply() public view returns (uint256) {
    return minted - burned;
  }
}

// File: contracts/Utilities.sol



//SPDX-License-Identifier: MIT

/*                          
                                .................                               
                          ......22222222222222222......                         
                       ......22244444444444444444222.....                       
                       ...222444444           444444222..                       
                    ...222444444                 44444422*..                    
                    ...222444                       44422*..                    
                    ...222444                       44422*..                    
                    ...222444                       44422*..                    
                    ...222444                       44422*..                    
                    ...222444                       44422*..                    
                    ...222444444                 44444422*..                    
                       ...222444444           444444222..                       
                       ......22244444444444444444222.....                       
                          ......22222222222222222......                         
                                .................
*/
pragma solidity ^0.8.12;

library utils {
  function assemblyKeccak(bytes memory _input) public pure returns (bytes32 x) {
    assembly {
      x := keccak256(add(_input, 0x20), mload(_input))
    }
  }

  function random(string memory input) internal pure returns (uint256) {
    return uint256(assemblyKeccak(abi.encodePacked(input)));
  }

  function randomRange(
    uint256 tokenId,
    string memory keyPrefix,
    uint256 lower,
    uint256 upper
  ) internal pure returns (uint256) {
    uint256 rand = random(string(abi.encodePacked(keyPrefix, uint2str(tokenId))));
    return (rand % (upper - lower + 1)) + lower;
  }

  function min(uint256 a, uint256 b) internal pure returns (uint256) {
    return a < b ? a : b;
  }

  function max(uint256 a, uint256 b) internal pure returns (uint256) {
    return a > b ? a : b;
  }

  function sliceUint(bytes memory bs, uint256 start) internal pure returns (uint256) {
    require(bs.length >= start + 32, "slicing out of range");
    uint256 x;
    assembly {
      x := mload(add(bs, add(0x20, start)))
    }
    return x;
  }

  // function getHslString(HSL memory _hsl) public pure returns (string memory) {
  //   return string(abi.encodePacked("hsl(", uint2str(_hsl.h), ",", uint2str(_hsl.s), "%,", uint2str(_hsl.l), "%)"));
  // }

  // function getHslString(
  //   uint256 _h,
  //   uint256 _s,
  //   uint256 _l
  // ) public pure returns (string memory) {
  //   return string(abi.encodePacked("hsl(", uint2str(_h), ",", uint2str(_s), "%,", uint2str(_l), "%)"));
  // }

  function getHslString(uint256[3] memory _hsl) public pure returns (string memory) {
    return string(abi.encodePacked("hsl(", uint2str(_hsl[0]), ",", uint2str(_hsl[1]), "%,", uint2str(_hsl[2]), "%)"));
  }

  function getHslString(uint256 _packedHsl) public pure returns (string memory) {
    // 3 colors per level, 3 color items per color, H/S/L are color items, 3 bytes each
    return
      string(
        abi.encodePacked(
          "hsl(",
          uint2str((_packedHsl >> (12 * 2)) & 0xFFF),
          ",",
          uint2str((_packedHsl >> (12 * 1)) & 0xFFF),
          "%,",
          uint2str((_packedHsl >> (12 * 0)) & 0xFFF),
          "%)"
        )
      );
  }

  function unpackHsl(uint256 _packedHsl) public pure returns (uint256[3] memory) {
    return [(_packedHsl >> (12 * 2)) & 0xFFF, (_packedHsl >> (12 * 1)) & 0xFFF, (_packedHsl >> (12 * 0)) & 0xFFF];
  }

  function uint2floatstr(uint256 _i_scaled, uint256 _decimals) internal pure returns (string memory) {
    return string.concat(uint2str(_i_scaled / (10**_decimals)), ".", uint2str(_i_scaled % (10**_decimals)));
  }

  function int2str(int256 _i) internal pure returns (string memory _uintAsString) {
    if (_i < 0) {
      return string.concat("-", uint2str(uint256(-_i)));
    } else {
      return uint2str(uint256(_i));
    }
  }

  // converts an unsigned integer to a string
  function uint2str(uint256 _i) internal pure returns (string memory _uintAsString) {
    if (_i == 0) {
      return "0";
    }
    uint256 j = _i;
    uint256 len;
    while (j != 0) {
      len++;
      j /= 10;
    }
    bytes memory bstr = new bytes(len);
    uint256 k = len;
    while (_i != 0) {
      k = k - 1;
      uint8 temp = (48 + uint8(_i - (_i / 10) * 10));
      bytes1 b1 = bytes1(temp);
      bstr[k] = b1;
      _i /= 10;
    }
    return string(bstr);
  }

  function sqrt(uint256 x) internal pure returns (uint256 z) {
    assembly {
      // This segment is to get a reasonable initial estimate for the Babylonian method.
      // If the initial estimate is bad, the number of correct bits increases ~linearly
      // each iteration instead of ~quadratically.
      // The idea is to get z*z*y within a small factor of x.
      // More iterations here gets y in a tighter range. Currently, we will have
      // y in [256, 256*2^16). We ensure y>= 256 so that the relative difference
      // between y and y+1 is small. If x < 256 this is not possible, but those cases
      // are easy enough to verify exhaustively.
      z := 181 // The 'correct' value is 1, but this saves a multiply later
      let y := x
      // Note that we check y>= 2^(k + 8) but shift right by k bits each branch,
      // this is to ensure that if x >= 256, then y >= 256.
      if iszero(lt(y, 0x10000000000000000000000000000000000)) {
        y := shr(128, y)
        z := shl(64, z)
      }
      if iszero(lt(y, 0x1000000000000000000)) {
        y := shr(64, y)
        z := shl(32, z)
      }
      if iszero(lt(y, 0x10000000000)) {
        y := shr(32, y)
        z := shl(16, z)
      }
      if iszero(lt(y, 0x1000000)) {
        y := shr(16, y)
        z := shl(8, z)
      }
      // Now, z*z*y <= x < z*z*(y+1), and y <= 2^(16+8),
      // and either y >= 256, or x < 256.
      // Correctness can be checked exhaustively for x < 256, so we assume y >= 256.
      // Then z*sqrt(y) is within sqrt(257)/sqrt(256) of x, or about 20bps.

      // The estimate sqrt(x) = (181/1024) * (x+1) is off by a factor of ~2.83 both when x=1
      // and when x = 256 or 1/256. In the worst case, this needs seven Babylonian iterations.
      z := shr(18, mul(z, add(y, 65536))) // A multiply is saved from the initial z := 181

      // Run the Babylonian method seven times. This should be enough given initial estimate.
      // Possibly with a quadratic/cubic polynomial above we could get 4-6.
      z := shr(1, add(z, div(x, z)))
      z := shr(1, add(z, div(x, z)))
      z := shr(1, add(z, div(x, z)))
      z := shr(1, add(z, div(x, z)))
      z := shr(1, add(z, div(x, z)))
      z := shr(1, add(z, div(x, z)))
      z := shr(1, add(z, div(x, z)))

      // See https://en.wikipedia.org/wiki/Integer_square_root#Using_only_integer_division.
      // If x+1 is a perfect square, the Babylonian method cycles between
      // floor(sqrt(x)) and ceil(sqrt(x)). This check ensures we return floor.
      // The solmate implementation assigns zRoundDown := div(x, z) first, but
      // since this case is rare, we choose to save gas on the assignment and
      // repeat division in the rare case.
      // If you don't care whether floor or ceil is returned, you can skip this.
      if lt(div(x, z), z) {
        z := div(x, z)
      }
    }
  }
}

// File: contracts/interfaces/BlackHole.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.12;

struct BlackHole {
  uint256 tokenId;
  uint256 level;
  uint256 size;
  uint256 mass;
  uint256 adjustment;
  string name;
}

// File: contracts/interfaces/ERC4906.sol



// SPDX-License-Identifier: CC0-1.0
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "./RefIERC4906.sol";

contract ERC4906 is ERC721, IERC4906 {
  constructor(string memory name_, string memory symbol_) ERC721(name_, symbol_) {}

  /// @dev See {IERC165-supportsInterface}.
  function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165, ERC721) returns (bool) {
    return interfaceId == bytes4(0x49064906) || super.supportsInterface(interfaceId);
  }
}

// File: contracts/interfaces/IBlackHoles.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.12;

import {IERC721} from "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import "./BlackHole.sol";

interface IBlackHoles is IERC721 {
  function blackHoleForTokenId(uint256 _tokenId) external view returns (BlackHole memory);

  function merge(uint256[] memory tokens) external;

  function massForTokenId(uint256 _tokenId) external view returns (uint256);

  function burn(uint256 _tokenId) external;

  function totalMinted() external view returns (uint256);

  function MAX_SUPPLY_OF_INTERSTELLAR() external view returns (uint256);

  function MAX_LEVEL() external view returns (uint256);

  function nameForBlackHoleLevel(uint256 _level) external view returns (string memory);
}

// File: contracts/interfaces/IRenderer.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.12;

import "./BlackHole.sol";

interface IRenderer {
  function PIXELS_PER_SIDE() external view returns (uint256);

  function getBlackHoleSVG(BlackHole memory _blackHole) external view returns (string memory);
}

// File: contracts/interfaces/RefIERC4906.sol



// SPDX-License-Identifier: CC0-1.0
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import "@openzeppelin/contracts/interfaces/IERC165.sol";

/// @title EIP-721 Metadata Update Extension
interface IERC4906 is IERC165, IERC721 {
  /// @dev This event emits when the metadata of a token is changed.
  /// So that the third-party platforms such as NFT market could
  /// timely update the images and related attributes of the NFT.
  event MetadataUpdate(uint256 _tokenId);

  /// @dev This event emits when the metadata of a range of tokens is changed.
  /// So that the third-party platforms such as NFT market could
  /// timely update the images and related attributes of the NFTs.
  event BatchMetadataUpdate(uint256 _fromTokenId, uint256 _toTokenId);
}

// File: svgnft/contracts/Base64.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2;

/// [MIT License]
/// @title Base64
/// @notice Provides a function for encoding some bytes in base64
/// @author Brecht Devos <brecht@loopring.org>
library Base64 {
  bytes internal constant TABLE = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

  /// @notice Encodes some bytes to the base64 representation
  function encode(bytes memory data) internal pure returns (string memory) {
    uint256 len = data.length;
    if (len == 0) return "";

    // multiply by 4/3 rounded up
    uint256 encodedLen = 4 * ((len + 2) / 3);

    // Add some extra buffer at the end
    bytes memory result = new bytes(encodedLen + 32);

    bytes memory table = TABLE;

    assembly {
      let tablePtr := add(table, 1)
      let resultPtr := add(result, 32)

      for {
        let i := 0
      } lt(i, len) {

      } {
        i := add(i, 3)
        let input := and(mload(add(data, i)), 0xffffff)

        let out := mload(add(tablePtr, and(shr(18, input), 0x3F)))
        out := shl(8, out)
        out := add(out, and(mload(add(tablePtr, and(shr(12, input), 0x3F))), 0xFF))
        out := shl(8, out)
        out := add(out, and(mload(add(tablePtr, and(shr(6, input), 0x3F))), 0xFF))
        out := shl(8, out)
        out := add(out, and(mload(add(tablePtr, and(input, 0x3F))), 0xFF))
        out := shl(224, out)

        mstore(resultPtr, out)

        resultPtr := add(resultPtr, 4)
      }

      switch mod(len, 3)
      case 1 {
        mstore(sub(resultPtr, 2), shl(240, 0x3d3d))
      }
      case 2 {
        mstore(sub(resultPtr, 1), shl(248, 0x3d))
      }

      mstore(result, encodedLen)
    }

    return string(result);
  }
}