Zapper - Season 2 Edition

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            size := extcodesize(account)
        }
        return size > 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"
        );

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(
            success,
            "Address: unable to send value, recipient may have reverted"
        );
    }

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

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

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

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

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) =
            target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

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

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

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

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

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

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) private pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT

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) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC1155.sol";
import "./IERC1155Receiver.sol";
import "./extensions/IERC1155MetadataURI.sol";
import "../utils/Address.sol";
import "../utils/Context.sol";
import "../utils/introspection/ERC165.sol";

/**
 * @dev Implementation of the basic standard multi-token.
 * See https://eips.ethereum.org/EIPS/eip-1155
 * Originally based on code by Enjin: https://github.com/enjin/erc-1155
 *
 * _Available since v3.1._
 */
contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
    using Address for address;

    // Mapping from token ID to account balances
    mapping(uint256 => mapping(address => uint256)) private _balances;

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

    // Used as the URI for all token types by relying on ID substitution, e.g. https://token-cdn-domain/{id}.json
    string private _uri;

    /**
     * @dev See {_setURI}.
     */
    constructor(string memory uri_) {
        _setURI(uri_);
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId)
        public
        view
        virtual
        override(ERC165, IERC165)
        returns (bool)
    {
        return
            interfaceId == type(IERC1155).interfaceId ||
            interfaceId == type(IERC1155MetadataURI).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC1155MetadataURI-uri}.
     *
     * This implementation returns the same URI for *all* token types. It relies
     * on the token type ID substitution mechanism
     * https://eips.ethereum.org/EIPS/eip-1155#metadata[defined in the EIP].
     *
     * Clients calling this function must replace the `\{id\}` substring with the
     * actual token type ID.
     */
    function uri(uint256) public view virtual override returns (string memory) {
        return _uri;
    }

    /**
     * @dev See {IERC1155-balanceOf}.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function balanceOf(address account, uint256 id)
        public
        view
        virtual
        override
        returns (uint256)
    {
        require(
            account != address(0),
            "ERC1155: balance query for the zero address"
        );
        return _balances[id][account];
    }

    /**
     * @dev See {IERC1155-balanceOfBatch}.
     *
     * Requirements:
     *
     * - `accounts` and `ids` must have the same length.
     */
    function balanceOfBatch(address[] memory accounts, uint256[] memory ids)
        public
        view
        virtual
        override
        returns (uint256[] memory)
    {
        require(
            accounts.length == ids.length,
            "ERC1155: accounts and ids length mismatch"
        );

        uint256[] memory batchBalances = new uint256[](accounts.length);

        for (uint256 i = 0; i < accounts.length; ++i) {
            batchBalances[i] = balanceOf(accounts[i], ids[i]);
        }

        return batchBalances;
    }

    /**
     * @dev See {IERC1155-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved)
        public
        virtual
        override
    {
        require(
            _msgSender() != operator,
            "ERC1155: setting approval status for self"
        );

        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC1155-isApprovedForAll}.
     */
    function isApprovedForAll(address account, address operator)
        public
        view
        virtual
        override
        returns (bool)
    {
        return _operatorApprovals[account][operator];
    }

    /**
     * @dev See {IERC1155-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) public virtual override {
        require(to != address(0), "ERC1155: transfer to the zero address");
        require(
            from == _msgSender() || isApprovedForAll(from, _msgSender()),
            "ERC1155: caller is not owner nor approved"
        );

        address operator = _msgSender();

        _beforeTokenTransfer(
            operator,
            from,
            to,
            _asSingletonArray(id),
            _asSingletonArray(amount),
            data
        );

        uint256 fromBalance = _balances[id][from];
        require(
            fromBalance >= amount,
            "ERC1155: insufficient balance for transfer"
        );
        _balances[id][from] = fromBalance - amount;
        _balances[id][to] += amount;

        emit TransferSingle(operator, from, to, id, amount);

        _doSafeTransferAcceptanceCheck(operator, from, to, id, amount, data);
    }

    /**
     * @dev See {IERC1155-safeBatchTransferFrom}.
     */
    function safeBatchTransferFrom(
        address from,
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) public virtual override {
        require(
            ids.length == amounts.length,
            "ERC1155: ids and amounts length mismatch"
        );
        require(to != address(0), "ERC1155: transfer to the zero address");
        require(
            from == _msgSender() || isApprovedForAll(from, _msgSender()),
            "ERC1155: transfer caller is not owner nor approved"
        );

        address operator = _msgSender();

        _beforeTokenTransfer(operator, from, to, ids, amounts, data);

        for (uint256 i = 0; i < ids.length; ++i) {
            uint256 id = ids[i];
            uint256 amount = amounts[i];

            uint256 fromBalance = _balances[id][from];
            require(
                fromBalance >= amount,
                "ERC1155: insufficient balance for transfer"
            );
            _balances[id][from] = fromBalance - amount;
            _balances[id][to] += amount;
        }

        emit TransferBatch(operator, from, to, ids, amounts);

        _doSafeBatchTransferAcceptanceCheck(
            operator,
            from,
            to,
            ids,
            amounts,
            data
        );
    }

    /**
     * @dev Sets a new URI for all token types, by relying on the token type ID
     * substitution mechanism
     * https://eips.ethereum.org/EIPS/eip-1155#metadata[defined in the EIP].
     *
     * By this mechanism, any occurrence of the `\{id\}` substring in either the
     * URI or any of the amounts in the JSON file at said URI will be replaced by
     * clients with the token type ID.
     *
     * For example, the `https://token-cdn-domain/\{id\}.json` URI would be
     * interpreted by clients as
     * `https://token-cdn-domain/000000000000000000000000000000000000000000000000000000000004cce0.json`
     * for token type ID 0x4cce0.
     *
     * See {uri}.
     *
     * Because these URIs cannot be meaningfully represented by the {URI} event,
     * this function emits no events.
     */
    function _setURI(string memory newuri) internal virtual {
        _uri = newuri;
    }

    /**
     * @dev Creates `amount` tokens of token type `id`, and assigns them to `account`.
     *
     * Emits a {TransferSingle} event.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - If `account` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
     * acceptance magic value.
     */
    function _mint(
        address account,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) internal virtual {
        require(account != address(0), "ERC1155: mint to the zero address");

        address operator = _msgSender();

        _beforeTokenTransfer(
            operator,
            address(0),
            account,
            _asSingletonArray(id),
            _asSingletonArray(amount),
            data
        );

        _balances[id][account] += amount;
        emit TransferSingle(operator, address(0), account, id, amount);

        _doSafeTransferAcceptanceCheck(
            operator,
            address(0),
            account,
            id,
            amount,
            data
        );
    }

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {_mint}.
     *
     * Requirements:
     *
     * - `ids` and `amounts` must have the same length.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
     * acceptance magic value.
     */
    function _mintBatch(
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) internal virtual {
        require(to != address(0), "ERC1155: mint to the zero address");
        require(
            ids.length == amounts.length,
            "ERC1155: ids and amounts length mismatch"
        );

        address operator = _msgSender();

        _beforeTokenTransfer(operator, address(0), to, ids, amounts, data);

        for (uint256 i = 0; i < ids.length; i++) {
            _balances[ids[i]][to] += amounts[i];
        }

        emit TransferBatch(operator, address(0), to, ids, amounts);

        _doSafeBatchTransferAcceptanceCheck(
            operator,
            address(0),
            to,
            ids,
            amounts,
            data
        );
    }

    /**
     * @dev Destroys `amount` tokens of token type `id` from `account`
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens of token type `id`.
     */
    function _burn(
        address account,
        uint256 id,
        uint256 amount
    ) internal virtual {
        require(account != address(0), "ERC1155: burn from the zero address");

        address operator = _msgSender();

        _beforeTokenTransfer(
            operator,
            account,
            address(0),
            _asSingletonArray(id),
            _asSingletonArray(amount),
            ""
        );

        uint256 accountBalance = _balances[id][account];
        require(
            accountBalance >= amount,
            "ERC1155: burn amount exceeds balance"
        );
        _balances[id][account] = accountBalance - amount;

        emit TransferSingle(operator, account, address(0), id, amount);
    }

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {_burn}.
     *
     * Requirements:
     *
     * - `ids` and `amounts` must have the same length.
     */
    function _burnBatch(
        address account,
        uint256[] memory ids,
        uint256[] memory amounts
    ) internal virtual {
        require(account != address(0), "ERC1155: burn from the zero address");
        require(
            ids.length == amounts.length,
            "ERC1155: ids and amounts length mismatch"
        );

        address operator = _msgSender();

        _beforeTokenTransfer(operator, account, address(0), ids, amounts, "");

        for (uint256 i = 0; i < ids.length; i++) {
            uint256 id = ids[i];
            uint256 amount = amounts[i];

            uint256 accountBalance = _balances[id][account];
            require(
                accountBalance >= amount,
                "ERC1155: burn amount exceeds balance"
            );
            _balances[id][account] = accountBalance - amount;
        }

        emit TransferBatch(operator, account, address(0), ids, amounts);
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning, as well as batched variants.
     *
     * The same hook is called on both single and batched variants. For single
     * transfers, the length of the `id` and `amount` arrays will be 1.
     *
     * Calling conditions (for each `id` and `amount` pair):
     *
     * - When `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * of token type `id` will be  transferred to `to`.
     * - When `from` is zero, `amount` tokens of token type `id` will be minted
     * for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens of token type `id`
     * will be burned.
     * - `from` and `to` are never both zero.
     * - `ids` and `amounts` have the same, non-zero length.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address operator,
        address from,
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) internal virtual {}

    function _doSafeTransferAcceptanceCheck(
        address operator,
        address from,
        address to,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) private {
        if (to.isContract()) {
            try
                IERC1155Receiver(to).onERC1155Received(
                    operator,
                    from,
                    id,
                    amount,
                    data
                )
            returns (bytes4 response) {
                if (
                    response != IERC1155Receiver(to).onERC1155Received.selector
                ) {
                    revert("ERC1155: ERC1155Receiver rejected tokens");
                }
            } catch Error(string memory reason) {
                revert(reason);
            } catch {
                revert("ERC1155: transfer to non ERC1155Receiver implementer");
            }
        }
    }

    function _doSafeBatchTransferAcceptanceCheck(
        address operator,
        address from,
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) private {
        if (to.isContract()) {
            try
                IERC1155Receiver(to).onERC1155BatchReceived(
                    operator,
                    from,
                    ids,
                    amounts,
                    data
                )
            returns (bytes4 response) {
                if (
                    response !=
                    IERC1155Receiver(to).onERC1155BatchReceived.selector
                ) {
                    revert("ERC1155: ERC1155Receiver rejected tokens");
                }
            } catch Error(string memory reason) {
                revert(reason);
            } catch {
                revert("ERC1155: transfer to non ERC1155Receiver implementer");
            }
        }
    }

    function _asSingletonArray(uint256 element)
        private
        pure
        returns (uint256[] memory)
    {
        uint256[] memory array = new uint256[](1);
        array[0] = element;

        return array;
    }
}

// SPDX-License-Identifier: MIT

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;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

/**
 * @dev Required interface of an ERC1155 compliant contract, as defined in the
 * https://eips.ethereum.org/EIPS/eip-1155[EIP].
 *
 * _Available since v3.1._
 */
interface IERC1155 is IERC165 {
    /**
     * @dev Emitted when `value` tokens of token type `id` are transferred from `from` to `to` by `operator`.
     */
    event TransferSingle(
        address indexed operator,
        address indexed from,
        address indexed to,
        uint256 id,
        uint256 value
    );

    /**
     * @dev Equivalent to multiple {TransferSingle} events, where `operator`, `from` and `to` are the same for all
     * transfers.
     */
    event TransferBatch(
        address indexed operator,
        address indexed from,
        address indexed to,
        uint256[] ids,
        uint256[] values
    );

    /**
     * @dev Emitted when `account` grants or revokes permission to `operator` to transfer their tokens, according to
     * `approved`.
     */
    event ApprovalForAll(
        address indexed account,
        address indexed operator,
        bool approved
    );

    /**
     * @dev Emitted when the URI for token type `id` changes to `value`, if it is a non-programmatic URI.
     *
     * If an {URI} event was emitted for `id`, the standard
     * https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[guarantees] that `value` will equal the value
     * returned by {IERC1155MetadataURI-uri}.
     */
    event URI(string value, uint256 indexed id);

    /**
     * @dev Returns the amount of tokens of token type `id` owned by `account`.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function balanceOf(address account, uint256 id)
        external
        view
        returns (uint256);

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {balanceOf}.
     *
     * Requirements:
     *
     * - `accounts` and `ids` must have the same length.
     */
    function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids)
        external
        view
        returns (uint256[] memory);

    /**
     * @dev Grants or revokes permission to `operator` to transfer the caller's tokens, according to `approved`,
     *
     * Emits an {ApprovalForAll} event.
     *
     * Requirements:
     *
     * - `operator` cannot be the caller.
     */
    function setApprovalForAll(address operator, bool approved) external;

    /**
     * @dev Returns true if `operator` is approved to transfer ``account``'s tokens.
     *
     * See {setApprovalForAll}.
     */
    function isApprovedForAll(address account, address operator)
        external
        view
        returns (bool);

    /**
     * @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
     *
     * Emits a {TransferSingle} event.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - If the caller is not `from`, it must be have been approved to spend ``from``'s tokens via {setApprovalForAll}.
     * - `from` must have a balance of tokens of type `id` of at least `amount`.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
     * acceptance magic value.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        uint256 amount,
        bytes calldata data
    ) external;

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {safeTransferFrom}.
     *
     * Emits a {TransferBatch} event.
     *
     * Requirements:
     *
     * - `ids` and `amounts` must have the same length.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
     * acceptance magic value.
     */
    function safeBatchTransferFrom(
        address from,
        address to,
        uint256[] calldata ids,
        uint256[] calldata amounts,
        bytes calldata data
    ) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC1155.sol";

/**
 * @dev Interface of the optional ERC1155MetadataExtension interface, as defined
 * in the https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[EIP].
 *
 * _Available since v3.1._
 */
interface IERC1155MetadataURI is IERC1155 {
    /**
     * @dev Returns the URI for token type `id`.
     *
     * If the `\{id\}` substring is present in the URI, it must be replaced by
     * clients with the actual token type ID.
     */
    function uri(uint256 id) external view returns (string memory);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

/**
 * @dev _Available since v3.1._
 */
interface IERC1155Receiver is IERC165 {
    /**
        @dev Handles the receipt of a single ERC1155 token type. This function is
        called at the end of a `safeTransferFrom` after the balance has been updated.
        To accept the transfer, this must return
        `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
        (i.e. 0xf23a6e61, or its own function selector).
        @param operator The address which initiated the transfer (i.e. msg.sender)
        @param from The address which previously owned the token
        @param id The ID of the token being transferred
        @param value The amount of tokens being transferred
        @param data Additional data with no specified format
        @return `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))` if transfer is allowed
    */
    function onERC1155Received(
        address operator,
        address from,
        uint256 id,
        uint256 value,
        bytes calldata data
    ) external returns (bytes4);

    /**
        @dev Handles the receipt of a multiple ERC1155 token types. This function
        is called at the end of a `safeBatchTransferFrom` after the balances have
        been updated. To accept the transfer(s), this must return
        `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
        (i.e. 0xbc197c81, or its own function selector).
        @param operator The address which initiated the batch transfer (i.e. msg.sender)
        @param from The address which previously owned the token
        @param ids An array containing ids of each token being transferred (order and length must match values array)
        @param values An array containing amounts of each token being transferred (order and length must match ids array)
        @param data Additional data with no specified format
        @return `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))` if transfer is allowed
    */
    function onERC1155BatchReceived(
        address operator,
        address from,
        uint256[] calldata ids,
        uint256[] calldata values,
        bytes calldata data
    ) external returns (bytes4);
}

// SPDX-License-Identifier: MIT

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);
}

// SPDX-License-Identifier: MIT

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() {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

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

// ███████╗░█████╗░██████╗░██████╗░███████╗██████╗░░░░███████╗██╗
// ╚════██║██╔══██╗██╔══██╗██╔══██╗██╔════╝██╔══██╗░░░██╔════╝██║
// ░░███╔═╝███████║██████╔╝██████╔╝█████╗░░██████╔╝░░░█████╗░░██║
// ██╔══╝░░██╔══██║██╔═══╝░██╔═══╝░██╔══╝░░██╔══██╗░░░██╔══╝░░██║
// ███████╗██║░░██║██║░░░░░██║░░░░░███████╗██║░░██║██╗██║░░░░░██║
// ╚══════╝╚═╝░░╚═╝╚═╝░░░░░╚═╝░░░░░╚══════╝╚═╝░░╚═╝╚═╝╚═╝░░░░░╚═╝
// Copyright (C) 2021 zapper
// Copyright (c) 2018 Tasuku Nakamura

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//

///@author Zapper
///@notice This contract checks if a message has been signed by a verified signer via personal_sign.
// SPDX-License-Identifier: GPL-2.0

pragma solidity ^0.8.0;

contract SignatureVerifier_V2 {
    address public signer;

    constructor(address _signer) {
        signer = _signer;
    }

    function verify(bytes32 messageHash, bytes memory signature)
        internal
        view
        returns (bool)
    {
        bytes32 ethSignedMessageHash = getEthSignedMessageHash(messageHash);

        return recoverSigner(ethSignedMessageHash, signature) == signer;
    }

    function getEthSignedMessageHash(bytes32 messageHash)
        internal
        pure
        returns (bytes32)
    {
        return
            keccak256(
                abi.encodePacked(
                    "\x19Ethereum Signed Message:\n32",
                    messageHash
                )
            );
    }

    function recoverSigner(
        bytes32 _ethSignedMessageHash,
        bytes memory _signature
    ) internal pure returns (address) {
        (bytes32 r, bytes32 s, uint8 v) = splitSignature(_signature);

        return ecrecover(_ethSignedMessageHash, v, r, s);
    }

    function splitSignature(bytes memory signature)
        internal
        pure
        returns (
            bytes32 r,
            bytes32 s,
            uint8 v
        )
    {
        require(signature.length == 65, "invalid signature length");

        assembly {
            r := mload(add(signature, 32))
            s := mload(add(signature, 64))
            v := byte(0, mload(add(signature, 96)))
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

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

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

// ███████╗░█████╗░██████╗░██████╗░███████╗██████╗░░░░███████╗██╗
// ╚════██║██╔══██╗██╔══██╗██╔══██╗██╔════╝██╔══██╗░░░██╔════╝██║
// ░░███╔═╝███████║██████╔╝██████╔╝█████╗░░██████╔╝░░░█████╗░░██║
// ██╔══╝░░██╔══██║██╔═══╝░██╔═══╝░██╔══╝░░██╔══██╗░░░██╔══╝░░██║
// ███████╗██║░░██║██║░░░░░██║░░░░░███████╗██║░░██║██╗██║░░░░░██║
// ╚══════╝╚═╝░░╚═╝╚═╝░░░░░╚═╝░░░░░╚══════╝╚═╝░░╚═╝╚═╝╚═╝░░░░░╚═╝
// Copyright (C) 2021 zapper

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//

///@author Zapper
///@notice This contract manages Zapper V2 NFTs and Volts.
/// Volts can be claimed through quests in order to mint various NFTs.
/// Crafting combines NFTs of the same type into higher tier NFTs. NFTs
/// can also be redemeed for Volts.

// SPDX-License-Identifier: GPL-2.0

pragma solidity ^0.8.0;
import "./ERC1155/ERC1155.sol";
import "./access/Ownable.sol";
import "./SignatureVerifier/SignatureVerifier_V2.sol";
import "./ERC1155/IERC1155.sol";
import "./utils/Strings.sol";

contract Zapper_NFT_V2_0_1 is ERC1155, Ownable, SignatureVerifier_V2 {
    // Used in pausable modifier
    bool public paused;

    // NFT name
    string public name;

    // NFT symbol
    string public symbol;

    // Season deadline
    uint256 public deadline;

    // Modifier to apply to cost of NFT when redeeming in bps
    uint256 public redeemModifier = 7500;

    // Quantity of NFTs consumed per crafting event
    uint256 public craftingRequirement = 3;

    // Mapping from token ID to token supply
    mapping(uint256 => uint256) private tokenSupply;

    // Mapping of accessory contracts that have permission to mint
    mapping(address => bool) public accessoryContract;

    // Total Volt supply
    uint256 public voltSupply;

    // Mapping from account to Volt balance
    mapping(address => uint256) public voltBalance;

    // Mapping from token ID to token existence
    mapping(uint256 => bool) private exists;

    // Mapping for the rarity classes for use in crafting
    mapping(uint256 => uint256) public nextRarity;

    // Mapping from token ID to token cost in volts
    mapping(uint256 => uint256) public cost;

    // Mapping from account to nonce
    mapping(address => uint256) public nonces;

    // Emitted when `account` claims Volts
    event ClaimVolts(
        address indexed account,
        uint256 voltsRecieved,
        uint256 nonce
    );

    // Emitted when `account` burns Volts
    event BurnVolts(address indexed account, uint256 voltsBurned);

    // Emitted when `account` mints one or more NFTs by spending Volts
    event Mint(address indexed account, uint256 voltsSpent);

    // Emitted when `account` redeems Volts by burning one or more NFTs
    event Redeem(address indexed account, uint256 voltsRecieved);

    // Emitted when `account` crafts one or more of the same NFT
    event Craft(address indexed account, uint256 craftID);

    // Emitted when `account` crafts multiple different NFTs
    event CraftBatch(address indexed account, uint256[] craftIDs);

    // Emitted when a new NFT type is added
    event Add(uint256 id, uint256 cost, uint256 nextRarity);

    // Emitted when the baseURI is updated
    event updateBaseURI(string uri);

    modifier pausable {
        require(!paused, "Paused");
        _;
    }

    modifier beforeDeadline {
        require(block.timestamp <= deadline, "Deadline elapsed");
        _;
    }

    constructor(
        string memory _name,
        string memory _symbol,
        string memory _uri,
        address signer,
        address manager,
        uint256 _deadline
    ) ERC1155(_uri) SignatureVerifier_V2(signer) {
        name = _name;
        symbol = _symbol;
        deadline = _deadline;
        transferOwnership(manager);
    }

    /**
     * @dev Adds a new NFT and initializes crafting params
     * @param costs An array of the cost of each ID. 0 if it cannot
     * be crafted
     * @param nextRarities An array of higher rarity IDs which can be
     * crafted from the ID. 0 if max rarity.
     */
    function add(
        uint256[] calldata ids,
        uint256[] calldata costs,
        uint256[] calldata nextRarities
    ) external onlyOwner {
        require(
            ids.length == costs.length && ids.length == nextRarities.length,
            "Mismatched array lengths"
        );

        for (uint256 i = 0; i < ids.length; i++) {
            uint256 newId = ids[i];
            require(!exists[newId], "ID already exists");
            require(newId != 0, "Invalid ID");

            exists[newId] = true;

            cost[newId] = costs[i];
            nextRarity[newId] = nextRarities[i];

            emit Add(newId, costs[i], nextRarities[i]);
        }
    }

    /**
     * @notice Claims Volts earned through quests
     * @param voltsEarned The quantity of Volts being awarded
     * @param signature The signature granting msg.sender the volts
     */
    function claimVolts(uint256 voltsEarned, bytes calldata signature)
        external
        pausable
        beforeDeadline
    {
        bytes32 messageHash =
            getMessageHash(msg.sender, voltsEarned, nonces[msg.sender]++);

        require(verify(messageHash, signature), "Invalid Signature");

        _createVolts(voltsEarned);

        emit ClaimVolts(msg.sender, voltsEarned, nonces[msg.sender]);
    }

    /**
     * @notice Burns Volts
     * @param voltsBurned The quantity of Volts being burned
     */
    function burnVolts(uint256 voltsBurned) external pausable {
        _burnVolts(voltsBurned);

        emit BurnVolts(msg.sender, voltsBurned);
    }

    /**
     * @notice Mints a desired quantity of a single NFT ID
     * in exchange for Volts
     * @param id The ID of the  NFT to mint
     * @param quantity The quantity of the NFT to mint
     */
    function mint(uint256 id, uint256 quantity) external pausable {
        require(exists[id], "Invalid ID");

        uint256 voltsSpent;

        if (!accessoryContract[msg.sender]) {
            require(cost[id] > 0, "Price not set");

            voltsSpent = cost[id] * quantity;
            _burnVolts(voltsSpent);
        }

        _mint(msg.sender, id, quantity, new bytes(0));

        emit Mint(msg.sender, voltsSpent);
    }

    /**
     * @notice Batch Mints desired quantities of different NFT IDs
     * in exchange for Volts
     * @param ids An array consisting of the IDs of the NFTs to mint
     * @param quantities  An array consisting of the quantities of the NFTs to mint
     */
    function mintBatch(uint256[] calldata ids, uint256[] calldata quantities)
        external
        pausable
    {
        require(ids.length == quantities.length, "Mismatched array lengths");

        uint256 voltsSpent;

        if (!accessoryContract[msg.sender]) {
            for (uint256 i = 0; i < ids.length; i++) {
                require(exists[ids[i]], "Invalid ID");
                require(cost[ids[i]] > 0, "Price not set");

                voltsSpent += cost[ids[i]] * quantities[i];
            }

            _burnVolts(voltsSpent);
        } else {
            for (uint256 i = 0; i < ids.length; i++) {
                require(exists[ids[i]], "Invalid ID");
            }
        }

        _mintBatch(msg.sender, ids, quantities, new bytes(0));

        emit Mint(msg.sender, voltsSpent);
    }

    /**
     * @notice Burns an NFT
     * @dev Does not award Volts!
     * @param id The ID of the  NFT to burn
     * @param quantity The quantity of the NFT to burn
     */
    function burn(uint256 id, uint256 quantity) external pausable {
        _burn(msg.sender, id, quantity);
    }

    /**
     * @notice Batch burns NFTs
     * @dev Does not award Volts!
     * @param ids An array consisting of the IDs of the  NFTs to burn
     * @param quantities An array consisting of the quantities
     * of each NFT to burn
     */
    function burnBatch(uint256[] calldata ids, uint256[] calldata quantities)
        external
        pausable
    {
        _burnBatch(msg.sender, ids, quantities);
    }

    /**
     * @notice Redeems an NFT for Volts. Redeeming NFTs is
     * subject to a modifier which returns some percentage of
     * the full cost of the NFT
     * @param id ID of the  NFT to redeem
     * @param quantity The quantity of the NFT being redeemed
     */
    function redeem(uint256 id, uint256 quantity) external pausable {
        require(cost[id] > 0, "Cannot redeem this type");

        _burn(msg.sender, id, quantity);

        uint256 voltsRecieved = (cost[id] * quantity * redeemModifier) / 10000;

        _createVolts(voltsRecieved);

        emit Redeem(msg.sender, voltsRecieved);
    }

    /**
     * @notice Redeems multiple NFTs for Volts. Redeeming NFTs is
     * subject to a modifier which returns some percentage of
     * the full cost of the NFT
     * @param ids An array consisting of the IDs of the NFTs to redeem
     * @param quantities An array consisting of the quantities of
     * each NFT to redeem
     */
    function redeemBatch(uint256[] calldata ids, uint256[] calldata quantities)
        external
        pausable
    {
        _burnBatch(msg.sender, ids, quantities);

        uint256 voltsRecieved;

        for (uint256 i = 0; i < ids.length; i++) {
            require(cost[ids[i]] > 0, "Cannot redeem this type");

            voltsRecieved +=
                (cost[ids[i]] * quantities[i] * redeemModifier) /
                10000;
        }

        _createVolts(voltsRecieved);

        emit Redeem(msg.sender, voltsRecieved);
    }

    /**
     * @notice Crafts higher tier NFTs with lower tier NFTs
     * @param id ID of the NFT used for crafting
     * @param quantity The quantity of id to consume in crafting
     */
    function craft(uint256 id, uint256 quantity) external pausable {
        uint256 craftID = nextRarity[id];
        require(craftID != 0, "Already maximum rarity");
        require(
            quantity % craftingRequirement == 0,
            "Incorrect quantity for crafting"
        );

        _burn(msg.sender, id, quantity);

        uint256 craftQuantity = quantity / craftingRequirement;

        _mint(msg.sender, craftID, craftQuantity, new bytes(0));

        emit Craft(msg.sender, craftID);
    }

    /**
     * @notice Crafts multiple different higher tier NFTs with
     * lower tier NFTs
     * @param ids An array consisting of the IDs of the NFT used for crafting
     * @param quantities An array consisting of the quantities of the NFT
     * to consume in crafting
     */
    function craftBatch(uint256[] calldata ids, uint256[] calldata quantities)
        external
        pausable
    {
        _burnBatch(msg.sender, ids, quantities);

        uint256[] memory craftQuantities = new uint256[](quantities.length);
        uint256[] memory craftIds = new uint256[](ids.length);

        for (uint256 i = 0; i < ids.length; i++) {
            uint256 craftID = nextRarity[ids[i]];
            require(craftID != 0, "Already maximum rarity");
            require(
                quantities[i] % craftingRequirement == 0,
                "Incorrect quantity for crafting"
            );

            craftIds[i] = craftID;
            craftQuantities[i] = quantities[i] / craftingRequirement;
        }

        _mintBatch(msg.sender, craftIds, craftQuantities, new bytes(0));

        emit CraftBatch(msg.sender, craftIds);
    }

    /**
     * @dev Function to set the URI for all NFT IDs
     */
    function setBaseURI(string calldata _uri) external onlyOwner {
        _setURI(_uri);

        emit updateBaseURI(_uri);
    }

    /**
     * @dev Returns the URI of a token given its ID
     * @param id ID of the token to query
     * @return uri of the token or an empty string if it does not exist
     */
    function uri(uint256 id) public view override returns (string memory) {
        require(exists[id], "URI query for nonexistent token");

        string memory baseUri = super.uri(0);
        return string(abi.encodePacked(baseUri, Strings.toString(id)));
    }

    /**
     * @notice Maps the rarity classes and Volt costs
     * for use in crafting
     * @param ids An array of the  IDs being updated
     * @param costs An array of the cost of each ID
     * @param nextRarities An array of higher rarity IDs which
     * can be crafted from the ID
     */
    function updateCraftingParameters(
        uint256[] calldata ids,
        uint256[] calldata costs,
        uint256[] calldata nextRarities
    ) external onlyOwner {
        require(
            ids.length == costs.length && ids.length == nextRarities.length,
            "Mismatched array lengths"
        );

        for (uint256 i = 0; i < ids.length; i++) {
            require(exists[ids[i]], "ID does not exist");

            cost[ids[i]] = costs[i];
            nextRarity[ids[i]] = nextRarities[i];
        }
    }

    /**
     * @dev Updates the modifier which is used when redeeming
     * NFTs for Volts
     */
    function updateRedeemModifier(uint256 _redeemModifier) external onlyOwner {
        redeemModifier = _redeemModifier;
    }

    /**
     * @dev Updates the crafting requirement modifier which determines
     * the quantity of NFTs that are burned in order to craft
     * higher rarity NFTs
     */
    function updateCraftingRequirement(uint256 _craftingRequirement)
        external
        onlyOwner
    {
        craftingRequirement = _craftingRequirement;
    }

    /**
     * @dev Updates the mapping of accessory contracts which have
     * special permssions to mint NFTs (lootbox, bridge, etc.)
     */
    function updateAccessoryContracts(address _accessoryContract, bool allowed)
        external
        onlyOwner
    {
        accessoryContract[_accessoryContract] = allowed;
    }

    /**
     * @dev Updates the deadline after which Volts can no longer be claimed
     */
    function updateDeadline(uint256 _deadline) external onlyOwner {
        deadline = _deadline;
    }

    /**
     * @dev Returns the total quantity for a token ID
     * @param id ID of the token to query
     * @return amount of token in existence
     */
    function totalSupply(uint256 id) external view returns (uint256) {
        return tokenSupply[id];
    }

    /**
     * @dev Pause or unpause the contract
     */
    function pause() external onlyOwner {
        paused = !paused;
    }

    /**
     * @dev Function to return the message hash that will be
     * signed by the signer
     */
    function getMessageHash(
        address account,
        uint256 volts,
        uint256 nonce
    ) public pure returns (bytes32) {
        return keccak256(abi.encodePacked(account, volts, nonce));
    }

    /**
     * @dev Internal override function for minting an NFT
     */
    function _mint(
        address account,
        uint256 id,
        uint256 amount,
        bytes memory data
    ) internal override {
        super._mint(account, id, amount, data);

        tokenSupply[id] += amount;
    }

    /**
     * @dev Internal override function for batch minting NFTs
     */
    function _mintBatch(
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) internal override {
        super._mintBatch(to, ids, amounts, data);

        for (uint256 i = 0; i < ids.length; i++) {
            tokenSupply[ids[i]] += amounts[i];
        }
    }

    /**
     * @dev Internal override function for burning an NFT
     */
    function _burn(
        address account,
        uint256 id,
        uint256 amount
    ) internal override {
        super._burn(account, id, amount);

        tokenSupply[id] -= amount;
    }

    /**
     * @dev Internal override function for batch burning NFTs
     */
    function _burnBatch(
        address account,
        uint256[] memory ids,
        uint256[] memory amounts
    ) internal override {
        super._burnBatch(account, ids, amounts);

        for (uint256 i; i < ids.length; i++) {
            tokenSupply[ids[i]] -= amounts[i];
        }
    }

    /**
     * @dev Internal function to create volts
     */
    function _createVolts(uint256 quantity) internal {
        voltBalance[msg.sender] += quantity;
        voltSupply += quantity;
    }

    /**
     * @dev Internal function to burn volts
     */
    function _burnVolts(uint256 quantity) internal {
        require(
            voltBalance[msg.sender] >= quantity,
            "Insufficient Volt balance"
        );

        voltBalance[msg.sender] -= quantity;
        voltSupply -= quantity;
    }
}

{
  "compilationTarget": {
    "contracts/NFT/Zapper_NFT_V2.sol": "Zapper_NFT_V2_0_1"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs",
    "useLiteralContent": true
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}