Taopad

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.23;

// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)

// OpenZeppelin Contracts (last updated v5.0.0) (utils/Context.sol)

/**
 * @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;
    }
}

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

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

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

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

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

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

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        if (owner() != _msgSender()) {
            revert OwnableUnauthorizedAccount(_msgSender());
        }
    }

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

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        if (newOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(newOwner);
    }

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

// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/ERC20.sol)

// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/IERC20.sol)

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the value of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 value) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the
     * allowance mechanism. `value` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 value) external returns (bool);
}

// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/extensions/IERC20Metadata.sol)

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

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

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/draft-IERC6093.sol)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * The default value of {decimals} is 18. To change this, you should override
 * this function so it returns a different value.
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 */
abstract contract ERC20 is Context, IERC20, IERC20Metadata, IERC20Errors {
    mapping(address account => uint256) private _balances;

    mapping(address account => mapping(address spender => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5.05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the default value returned by this function, unless
     * it's overridden.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `value`.
     */
    function transfer(address to, uint256 value) public virtual returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, value);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `value` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 value) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, value);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `value`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `value`.
     */
    function transferFrom(address from, address to, uint256 value) public virtual returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, value);
        _transfer(from, to, value);
        return true;
    }

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * NOTE: This function is not virtual, {_update} should be overridden instead.
     */
    function _transfer(address from, address to, uint256 value) internal {
        if (from == address(0)) {
            revert ERC20InvalidSender(address(0));
        }
        if (to == address(0)) {
            revert ERC20InvalidReceiver(address(0));
        }
        _update(from, to, value);
    }

    /**
     * @dev Transfers a `value` amount of tokens from `from` to `to`, or alternatively mints (or burns) if `from`
     * (or `to`) is the zero address. All customizations to transfers, mints, and burns should be done by overriding
     * this function.
     *
     * Emits a {Transfer} event.
     */
    function _update(address from, address to, uint256 value) internal virtual {
        if (from == address(0)) {
            // Overflow check required: The rest of the code assumes that totalSupply never overflows
            _totalSupply += value;
        } else {
            uint256 fromBalance = _balances[from];
            if (fromBalance < value) {
                revert ERC20InsufficientBalance(from, fromBalance, value);
            }
            unchecked {
                // Overflow not possible: value <= fromBalance <= totalSupply.
                _balances[from] = fromBalance - value;
            }
        }

        if (to == address(0)) {
            unchecked {
                // Overflow not possible: value <= totalSupply or value <= fromBalance <= totalSupply.
                _totalSupply -= value;
            }
        } else {
            unchecked {
                // Overflow not possible: balance + value is at most totalSupply, which we know fits into a uint256.
                _balances[to] += value;
            }
        }

        emit Transfer(from, to, value);
    }

    /**
     * @dev Creates a `value` amount of tokens and assigns them to `account`, by transferring it from address(0).
     * Relies on the `_update` mechanism
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * NOTE: This function is not virtual, {_update} should be overridden instead.
     */
    function _mint(address account, uint256 value) internal {
        if (account == address(0)) {
            revert ERC20InvalidReceiver(address(0));
        }
        _update(address(0), account, value);
    }

    /**
     * @dev Destroys a `value` amount of tokens from `account`, lowering the total supply.
     * Relies on the `_update` mechanism.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * NOTE: This function is not virtual, {_update} should be overridden instead
     */
    function _burn(address account, uint256 value) internal {
        if (account == address(0)) {
            revert ERC20InvalidSender(address(0));
        }
        _update(account, address(0), value);
    }

    /**
     * @dev Sets `value` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     *
     * Overrides to this logic should be done to the variant with an additional `bool emitEvent` argument.
     */
    function _approve(address owner, address spender, uint256 value) internal {
        _approve(owner, spender, value, true);
    }

    /**
     * @dev Variant of {_approve} with an optional flag to enable or disable the {Approval} event.
     *
     * By default (when calling {_approve}) the flag is set to true. On the other hand, approval changes made by
     * `_spendAllowance` during the `transferFrom` operation set the flag to false. This saves gas by not emitting any
     * `Approval` event during `transferFrom` operations.
     *
     * Anyone who wishes to continue emitting `Approval` events on the`transferFrom` operation can force the flag to
     * true using the following override:
     * ```
     * function _approve(address owner, address spender, uint256 value, bool) internal virtual override {
     *     super._approve(owner, spender, value, true);
     * }
     * ```
     *
     * Requirements are the same as {_approve}.
     */
    function _approve(address owner, address spender, uint256 value, bool emitEvent) internal virtual {
        if (owner == address(0)) {
            revert ERC20InvalidApprover(address(0));
        }
        if (spender == address(0)) {
            revert ERC20InvalidSpender(address(0));
        }
        _allowances[owner][spender] = value;
        if (emitEvent) {
            emit Approval(owner, spender, value);
        }
    }

    /**
     * @dev Updates `owner` s allowance for `spender` based on spent `value`.
     *
     * Does not update the allowance value in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Does not emit an {Approval} event.
     */
    function _spendAllowance(address owner, address spender, uint256 value) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            if (currentAllowance < value) {
                revert ERC20InsufficientAllowance(spender, currentAllowance, value);
            }
            unchecked {
                _approve(owner, spender, currentAllowance - value, false);
            }
        }
    }
}

// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/IERC20.sol)

// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/IERC20Metadata.sol)

// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/utils/SafeERC20.sol)

// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/extensions/IERC20Permit.sol)

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 *
 * ==== Security Considerations
 *
 * There are two important considerations concerning the use of `permit`. The first is that a valid permit signature
 * expresses an allowance, and it should not be assumed to convey additional meaning. In particular, it should not be
 * considered as an intention to spend the allowance in any specific way. The second is that because permits have
 * built-in replay protection and can be submitted by anyone, they can be frontrun. A protocol that uses permits should
 * take this into consideration and allow a `permit` call to fail. Combining these two aspects, a pattern that may be
 * generally recommended is:
 *
 * ```solidity
 * function doThingWithPermit(..., uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public {
 *     try token.permit(msg.sender, address(this), value, deadline, v, r, s) {} catch {}
 *     doThing(..., value);
 * }
 *
 * function doThing(..., uint256 value) public {
 *     token.safeTransferFrom(msg.sender, address(this), value);
 *     ...
 * }
 * ```
 *
 * Observe that: 1) `msg.sender` is used as the owner, leaving no ambiguity as to the signer intent, and 2) the use of
 * `try/catch` allows the permit to fail and makes the code tolerant to frontrunning. (See also
 * {SafeERC20-safeTransferFrom}).
 *
 * Additionally, note that smart contract wallets (such as Argent or Safe) are not able to produce permit signatures, so
 * contracts should have entry points that don't rely on permit.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     *
     * CAUTION: See Security Considerations above.
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// OpenZeppelin Contracts (last updated v5.0.0) (utils/Address.sol)

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev The ETH balance of the account is not enough to perform the operation.
     */
    error AddressInsufficientBalance(address account);

    /**
     * @dev There's no code at `target` (it is not a contract).
     */
    error AddressEmptyCode(address target);

    /**
     * @dev A call to an address target failed. The target may have reverted.
     */
    error FailedInnerCall();

    /**
     * @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://consensys.net/diligence/blog/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/v0.8.20/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        if (address(this).balance < amount) {
            revert AddressInsufficientBalance(address(this));
        }

        (bool success, ) = recipient.call{value: amount}("");
        if (!success) {
            revert FailedInnerCall();
        }
    }

    /**
     * @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 or custom error, it is bubbled
     * up by this function (like regular Solidity function calls). However, if
     * the call reverted with no returned reason, this function reverts with a
     * {FailedInnerCall} error.
     *
     * 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.
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0);
    }

    /**
     * @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`.
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        if (address(this).balance < value) {
            revert AddressInsufficientBalance(address(this));
        }
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

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

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

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and reverts if the target
     * was not a contract or bubbling up the revert reason (falling back to {FailedInnerCall}) in case of an
     * unsuccessful call.
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata
    ) internal view returns (bytes memory) {
        if (!success) {
            _revert(returndata);
        } else {
            // only check if target is a contract if the call was successful and the return data is empty
            // otherwise we already know that it was a contract
            if (returndata.length == 0 && target.code.length == 0) {
                revert AddressEmptyCode(target);
            }
            return returndata;
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and reverts if it wasn't, either by bubbling the
     * revert reason or with a default {FailedInnerCall} error.
     */
    function verifyCallResult(bool success, bytes memory returndata) internal pure returns (bytes memory) {
        if (!success) {
            _revert(returndata);
        } else {
            return returndata;
        }
    }

    /**
     * @dev Reverts with returndata if present. Otherwise reverts with {FailedInnerCall}.
     */
    function _revert(bytes memory returndata) 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 FailedInnerCall();
        }
    }
}

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    /**
     * @dev An operation with an ERC20 token failed.
     */
    error SafeERC20FailedOperation(address token);

    /**
     * @dev Indicates a failed `decreaseAllowance` request.
     */
    error SafeERC20FailedDecreaseAllowance(address spender, uint256 currentAllowance, uint256 requestedDecrease);

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeCall(token.transfer, (to, value)));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeCall(token.transferFrom, (from, to, value)));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        forceApprove(token, spender, oldAllowance + value);
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `requestedDecrease`. If `token` returns no
     * value, non-reverting calls are assumed to be successful.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 requestedDecrease) internal {
        unchecked {
            uint256 currentAllowance = token.allowance(address(this), spender);
            if (currentAllowance < requestedDecrease) {
                revert SafeERC20FailedDecreaseAllowance(spender, currentAllowance, requestedDecrease);
            }
            forceApprove(token, spender, currentAllowance - requestedDecrease);
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
     * to be set to zero before setting it to a non-zero value, such as USDT.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeCall(token.approve, (spender, value));

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeCall(token.approve, (spender, 0)));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data);
        if (returndata.length != 0 && !abi.decode(returndata, (bool))) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return success && (returndata.length == 0 || abi.decode(returndata, (bool))) && address(token).code.length > 0;
    }
}

// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/extensions/ERC20Burnable.sol)

/**
 * @dev Extension of {ERC20} that allows token holders to destroy both their own
 * tokens and those that they have an allowance for, in a way that can be
 * recognized off-chain (via event analysis).
 */
abstract contract ERC20Burnable is Context, ERC20 {
    /**
     * @dev Destroys a `value` amount of tokens from the caller.
     *
     * See {ERC20-_burn}.
     */
    function burn(uint256 value) public virtual {
        _burn(_msgSender(), value);
    }

    /**
     * @dev Destroys a `value` amount of tokens from `account`, deducting from
     * the caller's allowance.
     *
     * See {ERC20-_burn} and {ERC20-allowance}.
     *
     * Requirements:
     *
     * - the caller must have allowance for ``accounts``'s tokens of at least
     * `value`.
     */
    function burnFrom(address account, uint256 value) public virtual {
        _spendAllowance(account, _msgSender(), value);
        _burn(account, value);
    }
}

// OpenZeppelin Contracts (last updated v5.0.0) (utils/ReentrancyGuard.sol)

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

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

    uint256 private _status;

    /**
     * @dev Unauthorized reentrant call.
     */
    error ReentrancyGuardReentrantCall();

    constructor() {
        _status = NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be NOT_ENTERED
        if (_status == ENTERED) {
            revert ReentrancyGuardReentrantCall();
        }

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

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

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == ENTERED;
    }
}

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

interface IUniswapV2Router01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

pragma abicoder v2;

/// @title Callback for IUniswapV3PoolActions#swap
/// @notice Any contract that calls IUniswapV3PoolActions#swap must implement this interface
interface IUniswapV3SwapCallback {
    /// @notice Called to `msg.sender` after executing a swap via IUniswapV3Pool#swap.
    /// @dev In the implementation you must pay the pool tokens owed for the swap.
    /// The caller of this method must be checked to be a UniswapV3Pool deployed by the canonical UniswapV3Factory.
    /// amount0Delta and amount1Delta can both be 0 if no tokens were swapped.
    /// @param amount0Delta The amount of token0 that was sent (negative) or must be received (positive) by the pool by
    /// the end of the swap. If positive, the callback must send that amount of token0 to the pool.
    /// @param amount1Delta The amount of token1 that was sent (negative) or must be received (positive) by the pool by
    /// the end of the swap. If positive, the callback must send that amount of token1 to the pool.
    /// @param data Any data passed through by the caller via the IUniswapV3PoolActions#swap call
    function uniswapV3SwapCallback(
        int256 amount0Delta,
        int256 amount1Delta,
        bytes calldata data
    ) external;
}

/// @title Router token swapping functionality
/// @notice Functions for swapping tokens via Uniswap V3
interface ISwapRouter is IUniswapV3SwapCallback {
    struct ExactInputSingleParams {
        address tokenIn;
        address tokenOut;
        uint24 fee;
        address recipient;
        uint256 deadline;
        uint256 amountIn;
        uint256 amountOutMinimum;
        uint160 sqrtPriceLimitX96;
    }

    /// @notice Swaps `amountIn` of one token for as much as possible of another token
    /// @param params The parameters necessary for the swap, encoded as `ExactInputSingleParams` in calldata
    /// @return amountOut The amount of the received token
    function exactInputSingle(ExactInputSingleParams calldata params) external payable returns (uint256 amountOut);

    struct ExactInputParams {
        bytes path;
        address recipient;
        uint256 deadline;
        uint256 amountIn;
        uint256 amountOutMinimum;
    }

    /// @notice Swaps `amountIn` of one token for as much as possible of another along the specified path
    /// @param params The parameters necessary for the multi-hop swap, encoded as `ExactInputParams` in calldata
    /// @return amountOut The amount of the received token
    function exactInput(ExactInputParams calldata params) external payable returns (uint256 amountOut);

    struct ExactOutputSingleParams {
        address tokenIn;
        address tokenOut;
        uint24 fee;
        address recipient;
        uint256 deadline;
        uint256 amountOut;
        uint256 amountInMaximum;
        uint160 sqrtPriceLimitX96;
    }

    /// @notice Swaps as little as possible of one token for `amountOut` of another token
    /// @param params The parameters necessary for the swap, encoded as `ExactOutputSingleParams` in calldata
    /// @return amountIn The amount of the input token
    function exactOutputSingle(ExactOutputSingleParams calldata params) external payable returns (uint256 amountIn);

    struct ExactOutputParams {
        bytes path;
        address recipient;
        uint256 deadline;
        uint256 amountOut;
        uint256 amountInMaximum;
    }

    /// @notice Swaps as little as possible of one token for `amountOut` of another along the specified path (reversed)
    /// @param params The parameters necessary for the multi-hop swap, encoded as `ExactOutputParams` in calldata
    /// @return amountIn The amount of the input token
    function exactOutput(ExactOutputParams calldata params) external payable returns (uint256 amountIn);
}

/// @title ERC20 rewards
/// @author @niera26
/// @notice buy and sell tax on this token with rewardToken as rewards
/// @notice source: https://github.com/niera26/erc20-rewards-contracts
contract ERC20Rewards is Ownable, ERC20, ERC20Burnable, ReentrancyGuard {
    using SafeERC20 for IERC20;
    using SafeERC20 for IERC20Metadata;

    // =========================================================================
    // dependencies.
    // =========================================================================

    ISwapRouter public constant swapRouter = ISwapRouter(0xE592427A0AEce92De3Edee1F18E0157C05861564);
    IUniswapV2Router02 public constant router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
    IERC20Metadata public constant rewardToken = IERC20Metadata(0x77E06c9eCCf2E797fd462A92B6D7642EF85b0A44); // wTAO

    // =========================================================================
    // rewards management.
    // =========================================================================

    // numerator multiplier so tokenPerShare does not get rounded to 0.
    uint256 private constant PRECISION = 1e18;

    // scale factor so reward token scales to 18 decimals.
    uint256 private immutable SCALE_FACTOR;

    // the accumulated amount of reward token per share.
    uint256 private tokenPerShare;

    // total shares of this token.
    // (different from total supply because of fees and excluded wallets).
    uint256 public totalShares;

    // shareholders record.
    // (non excluded addresses are updated after they send/receive tokens).
    mapping(address => Share) private shareholders;

    struct Share {
        uint256 amount; // recorded balance after last transfer.
        uint256 earned; // amount of tokens earned but not claimed yet.
        uint256 tokenPerShareLast; // token per share value of the last earn occurrence.
    }

    // total amount of reward tokens ever claimed by holders.
    uint256 public totalRewardClaimed;

    // total amount of reward tokens ever distributed.
    uint256 public totalRewardDistributed;

    // amm pair addresses the tranfers from/to are taxed.
    // (populated with WETH/this token pair address in the constructor).
    mapping(address => bool) public pairs;

    // contract addresses that opted in for rewards.
    mapping(address => bool) public isOptin;

    // =========================================================================
    // reward donations.
    // =========================================================================

    // the number of reward tokens to emit per block.
    uint256 public rewardTokenPerBlock;

    // the amout of reward tokens already emitted.
    uint256 public emittedRewardsAcc;

    // last block reward tokens has been emitted.
    uint256 public lastEmittingBlock;

    // =========================================================================
    // operator address.
    // =========================================================================

    // the operator address receive marketing tax and can set non critical
    // settings. Allows to renounce ownership of critical settings. It is the
    // same as the owner by default and receive marketing tax. It can:
    // - update itself.
    // - set uniswap V3 pool fee setting.
    // - set the reward token per block rate.
    address public operator;

    // =========================================================================
    // anti-bot and limitations.
    // =========================================================================

    mapping(address => bool) public isBlacklisted;

    uint256 public maxWallet = type(uint256).max; // set to 1% in initialize
    uint256 public startBlock = 0;
    uint8 public deadBlocks = 1;

    // =========================================================================
    // pool options.
    // =========================================================================

    uint24 public poolFee = 10000; // works for wTAO

    // =========================================================================
    // fees.
    // =========================================================================

    uint24 public constant maxSwapFee = 3000;
    uint24 public constant maxMarketingFee = 8000;
    uint24 public constant feeDenominator = 10000;

    uint24 public buyFee = 2400;
    uint24 public sellFee = 2400;
    uint24 public marketingFee = 8000;

    // =========================================================================
    // events.
    // =========================================================================

    event OptIn(address addr);
    event OptOut(address addr);
    event AddToBlacklist(address addr);
    event RemoveFromBlacklist(address addr);
    event Claim(address indexed addr, address indexed to, uint256 amount);
    event Distribute(address indexed addr, uint256 amount);
    event Sweep(address indexed addr, address indexed token, uint256 amount);

    // =========================================================================
    // modifiers.
    // =========================================================================

    modifier onlyOperator() {
        require(msg.sender == operator, "!operator");
        _;
    }

    // =========================================================================
    // constructor.
    // =========================================================================

    constructor(string memory name, string memory symbol, uint256 _totalSupply)
        Ownable(msg.sender)
        ERC20(name, symbol)
    {
        // operator is deployer by default.
        operator = msg.sender;

        // set the reward token scale factor.
        uint8 rewardTokenDecimals = rewardToken.decimals();

        require(rewardTokenDecimals <= 18, "reward token decimals must be <= 18");

        SCALE_FACTOR = 10 ** (18 - rewardTokenDecimals);

        // mint total supply to itself.
        _mint(address(this), _totalSupply * 10 ** decimals());
    }

    // =========================================================================
    // exposed contract values.
    // =========================================================================

    /**
     * Return the remaining rewards === reward balance - emitted rewards.
     */
    function remainingRewards() public view returns (uint256) {
        return rewardBalance() - emittedRewards();
    }

    /**
     * Return the reward balance === balance - what's remaining to claim.
     *
     * It is the amount that can be emitted in total.
     */
    function rewardBalance() public view returns (uint256) {
        uint256 amountToClaim = totalRewardDistributed - totalRewardClaimed;

        return rewardToken.balanceOf(address(this)) - amountToClaim;
    }

    /**
     * Return the amount of emitted reward since the last block rewards has
     * been emitted, according to the reward token per block.
     */
    function emittedRewards() public view returns (uint256) {
        if (lastEmittingBlock == 0) return 0;
        if (rewardTokenPerBlock == 0) return 0;

        uint256 balance = rewardBalance();

        if (balance == 0) return 0;

        uint256 emitted = emittedRewardsAcc + (rewardTokenPerBlock * (block.number - lastEmittingBlock));

        return emitted < balance ? emitted : balance;
    }

    /**
     * Return the amount of reward tokens the given address can claim.
     */
    function pendingRewards(address addr) external view returns (uint256) {
        return _pendingRewards(shareholders[addr]);
    }

    // =========================================================================
    // exposed user functions.
    // =========================================================================

    /**
     * Claim reward tokens and send them to given address.
     */
    function claim(address to) external nonReentrant {
        Share storage share = shareholders[msg.sender];

        _earn(share);

        uint256 amountToClaim = share.earned;

        if (amountToClaim == 0) return;

        share.earned = 0;

        totalRewardClaimed += amountToClaim;

        rewardToken.safeTransfer(to, amountToClaim);

        emit Claim(msg.sender, to, amountToClaim);
    }

    /**
     * Create a pair between this token and the given token.
     */
    function createAmmPairWith(address token) public {
        IUniswapV2Factory factory = IUniswapV2Factory(router.factory());

        address pair = factory.createPair(token, address(this));

        pairs[pair] = true;
    }

    /**
     * Register an existing pair between this token and the given token.
     */
    function recordAmmPairWith(address token) public {
        IUniswapV2Factory factory = IUniswapV2Factory(router.factory());

        address pair = factory.getPair(token, address(this));

        pairs[pair] = true;
    }

    /**
     * Optin for rewards when you are excluded from rewards (contracts).
     */
    function rewardOptin() external {
        _includeToRewards(msg.sender);

        isOptin[msg.sender] = true;

        emit OptIn(msg.sender);
    }

    /**
     * Optout for rewards when you are included to rewards (contracts).
     */
    function rewardOptout() external {
        _removeFromRewards(msg.sender);

        isOptin[msg.sender] = false;

        emit OptOut(msg.sender);
    }

    /**
     * Swap the collected tax to ETH.
     *
     * Pass minimal expected amount to prevent slippage/frontrun.
     */
    function swapCollectedTax(uint256 amountOutMin) public {
        // return if no tax collected.
        uint256 amountIn = balanceOf(address(this));

        if (amountIn == 0) return;

        // swap tax to eth.
        uint256 collectedEth = _swapTokenToETHV2(address(this), amountIn, amountOutMin);

        // collect marketing tax.
        uint256 marketingAmount = (collectedEth * marketingFee) / feeDenominator;

        if (marketingAmount > 0) {
            payable(operator).transfer(marketingAmount);
        }
    }

    /**
     * Distribute reward token.
     *
     * Pass minimal expected amount to prevent slippage/frontrun.
     */
    function distribute(uint256 amountOutMinimum) public {
        if (totalShares == 0) return;

        // distribute the rewards that was emitted since last update.
        uint256 amountToDistribute = emittedRewards();

        // swap eth balance to reward token and add it to amount to distribute.
        uint256 amountIn = address(this).balance;

        if (amountIn > 0) {
            amountToDistribute += _swapETHToRewardV3(address(this), amountIn, amountOutMinimum);
        }

        // stop when no rewards.
        if (amountToDistribute == 0) return;

        // distribute rewards.
        tokenPerShare += (amountToDistribute * SCALE_FACTOR * PRECISION) / totalShares;
        totalRewardDistributed += amountToDistribute;

        // reset emitted rewards.
        emittedRewardsAcc = 0;
        lastEmittingBlock = block.number;

        emit Distribute(msg.sender, amountToDistribute);
    }

    /**
     * Sweep any other ERC20 mistakenly sent to this contract.
     */
    function sweep(IERC20 otherToken) external {
        require(address(otherToken) != address(this), "!sweep");
        require(address(otherToken) != address(rewardToken), "!sweep");

        uint256 amount = otherToken.balanceOf(address(this));

        otherToken.safeTransfer(msg.sender, amount);

        emit Sweep(msg.sender, address(otherToken), amount);
    }

    // =========================================================================
    // exposed admin functions.
    // =========================================================================

    /**
     * Send initial allocations before trading started.
     */
    function allocate(address to, uint256 amount) external onlyOwner {
        require(startBlock == 0, "!initialized");

        this.transfer(to, amount);
    }

    /**
     * Remove max wallet limits, one shoot.
     */
    function removeLimits() external onlyOwner {
        maxWallet = type(uint256).max;
    }

    /**
     * Set the fees.
     */
    function setFee(uint24 _buyFee, uint24 _sellFee, uint24 _marketingFee) external onlyOwner {
        require(_buyFee <= maxSwapFee, "!buyFee");
        require(_sellFee <= maxSwapFee, "!sellFee");
        require(_marketingFee <= maxMarketingFee, "!marketingFee");

        buyFee = _buyFee;
        sellFee = _sellFee;
        marketingFee = _marketingFee;
    }

    /**
     * Remove the given address from the blacklist.
     */
    function removeFromBlacklist(address addr) external onlyOwner {
        _removeFromBlacklist(addr);
    }

    /**
     * Initialize the trading with the given eth and this contract balance.
     *
     * Starts trading, sets max wallet to 1% of the supply, create the uniswap V2 pair
     * with ETH, adds liquidity.
     *
     * LP tokens are sent to owner.
     */
    function initialize() external payable onlyOwner {
        require(msg.value > 0, "!liquidity");
        require(startBlock == 0, "!initialized");

        // start deadblocks from there.
        startBlock = block.number;

        // init max wallet to 1%.
        maxWallet = totalSupply() / 100;

        // the all balance will be put in the LP.
        uint256 balance = balanceOf(address(this));

        // create an amm pair with WETH.
        // as a contract, pair is automatically excluded from rewards.
        createAmmPairWith(router.WETH());

        // approve router to use total balance.
        _approve(address(this), address(router), balance);

        // add liquidity and send LP to owner.
        router.addLiquidityETH{value: msg.value}(address(this), balance, 0, 0, msg.sender, block.timestamp);
    }

    // =========================================================================
    // exposed operator functions.
    // =========================================================================

    /**
     * Operator can update itself.
     */
    function setOperator(address _operator) external onlyOperator {
        require(address(0) != _operator, "!address");
        operator = _operator;
    }

    /**
     * Set the uniswap V3 pool fee.
     */
    function setPoolFee(uint24 _poolFee) external onlyOperator {
        poolFee = _poolFee;
    }

    /**
     * Set the reward token per block. Accumulates the emitted rewards until this
     * block before updating the value.
     */
    function setRewardTokenPerBlock(uint256 _rewardTokenPerBlock) external onlyOperator {
        emittedRewardsAcc = emittedRewards();
        rewardTokenPerBlock = _rewardTokenPerBlock;
        lastEmittingBlock = block.number;
    }

    /**
     * Set the reward token per block without accumulating what has been
     * emitted. Fallback is case of an error.
     */
    function setRewardTokenPerBlockUnsafe(uint256 _rewardTokenPerBlock) external onlyOperator {
        rewardTokenPerBlock = _rewardTokenPerBlock;
    }

    /**
     * Empty the emitted rewards. Fallback in case of error.
     */
    function resetEmittedRewardsUnsafe() external onlyOperator {
        emittedRewardsAcc = 0;
    }

    // =========================================================================
    // internal functions.
    // =========================================================================

    /**
     * Return whether current block is a dead block (= blacklisted when buying in a dead block).
     */
    function _isDeadBlock() private view returns (bool) {
        return block.number <= startBlock + deadBlocks;
    }

    /**
     * Return addresses excluded from max wallet limit (= this contract, router or pairs).
     *
     * Blacklisted addresses are excluded too so they can buy as much as they want.
     */
    function _isExcludedFromMaxWallet(address addr) private view returns (bool) {
        return address(this) == addr || address(router) == addr || pairs[addr] || isBlacklisted[addr];
    }

    /**
     * Return adresses excluded from taxes (= this contract or router).
     */
    function _isExcludedFromTaxes(address addr) private view returns (bool) {
        return address(this) == addr || address(router) == addr;
    }

    /**
     * Retrun addresses excluded from rewards.
     *
     * - addresses of contracts that didn't opted in for rewards.
     * - blacklisted addresses.
     * - zero address to save gas on mint/burn (its balance is always 0 so it would never get shares anyway)
     * - this contract address is removed too because address(this).code.length == 0 in the constructor.
     * - remove dead address because people are used to it.
     */
    function _isExcludedFromRewards(address addr) private view returns (bool) {
        return address(0) == addr || address(this) == addr || (addr.code.length > 0 && !isOptin[addr])
            || isBlacklisted[addr] || 0x000000000000000000000000000000000000dEaD == addr;
    }

    /**
     * Add the given address to blacklist.
     */
    function _addToBlacklist(address addr) private {
        _removeFromRewards(addr);

        isBlacklisted[addr] = true;

        emit AddToBlacklist(addr);
    }

    /**
     * Remove the given address from blacklist.
     */
    function _removeFromBlacklist(address addr) private {
        _includeToRewards(addr);

        isBlacklisted[addr] = false;

        emit RemoveFromBlacklist(addr);
    }

    /**
     * Include the given address to rewards. Should only concern:
     *
     * - addresses of contracts opting in for rewards.
     * - addresses being removed from blacklist.
     */
    function _includeToRewards(address addr) private {
        // ensure we dont update total shares twice.
        if (!_isExcludedFromRewards(addr)) return;

        // update total shares.
        uint256 balance = balanceOf(addr);

        totalShares += balance;

        // restart earning from now.
        Share storage share = shareholders[addr];

        share.amount = balance;
        share.tokenPerShareLast = tokenPerShare;
    }

    /**
     * Remove the given address from rewards. Should only concern:
     *
     * - addresses of contracts opting out of rewards.
     * - addresses being added to blacklist.
     */
    function _removeFromRewards(address addr) private {
        // ensure we dont update total shares twice.
        if (_isExcludedFromRewards(addr)) return;

        // update total shares.
        totalShares -= balanceOf(addr);

        // make sure pending rewards are earned and stop earning (share.amount = 0)
        Share storage share = shareholders[addr];

        _earn(share);

        share.amount = 0;
    }

    /**
     * Compute the pending rewards of the given share.
     *
     * The rewards earned since the last transfer are added to the already earned
     * rewards.
     */
    function _pendingRewards(Share memory share) private view returns (uint256) {
        uint256 RDiff = tokenPerShare - share.tokenPerShareLast;
        uint256 earned = (share.amount * RDiff) / (SCALE_FACTOR * PRECISION);

        return share.earned + earned;
    }

    /**
     * Earn the rewards of the given share.
     */
    function _earn(Share storage share) private {
        uint256 pending = _pendingRewards(share);

        share.earned = pending;
        share.tokenPerShareLast = tokenPerShare;
    }

    /**
     * Override the update method in order to take fee when transfer is from/to
     * a registered amm pair.
     *
     * - transfers from/to registered pairs are taxed.
     * - addresses buying in a deadblock are blacklisted and cant transfer tokens anymore.
     * - prevents receiving address to get more than max wallet.
     * - taxed tokens are sent to this very contract.
     * - on a taxed sell, the collected tax is swapped for eth.
     * - updates the shares of both the from and to addresses.
     */
    function _update(address from, address to, uint256 amount) internal override {
        // blacklisted addresses cant transfer tokens.
        require(!isBlacklisted[from], "blacklisted");

        // check if it is a taxed buy or sell.
        bool isTaxedBuy = pairs[from] && !_isExcludedFromTaxes(to);
        bool isTaxedSell = !_isExcludedFromTaxes(from) && pairs[to];

        // take the fee if it is a buy or sell.
        uint256 fee = (isTaxedBuy ? buyFee : 0) + (isTaxedSell ? sellFee : 0);

        uint256 taxAmount = (amount * fee) / feeDenominator;

        uint256 actualTransferAmount = amount - taxAmount;

        // add to blacklist while buying in dead block.
        if (isTaxedBuy && _isDeadBlock()) {
            _addToBlacklist(to);
        }

        // prevents max wallet for regular addresses.
        if (!_isExcludedFromMaxWallet(to)) {
            require(actualTransferAmount + balanceOf(to) <= maxWallet, "!maxWallet");
        }

        // transfer the tax to this contract if any.
        if (taxAmount > 0) {
            super._update(from, address(this), taxAmount);
        }

        // swaps the tax to eth if it is a taxed sell.
        if (isTaxedSell) {
            swapCollectedTax(0);
        }

        // transfer the actual amount.
        super._update(from, to, actualTransferAmount);

        // updates shareholders values.
        _updateShare(from);
        _updateShare(to);
    }

    /**
     * Update the total shares and the shares of the given address if it is not
     * excluded from rewards.
     *
     * Earn first with his current share amount then update shares according to
     * its new balance.
     */
    function _updateShare(address addr) private {
        if (_isExcludedFromRewards(addr)) return;

        uint256 balance = balanceOf(addr);

        Share storage share = shareholders[addr];

        totalShares = totalShares - share.amount + balance;

        _earn(share);

        share.amount = balance;
    }

    /**
     * Swap amount of this token for ETH to address and return the amount received.
     */
    function _swapTokenToETHV2(address to, uint256 amountIn, uint256 amountOutMin) private returns (uint256) {
        // return 0 if no amount given.
        if (amountIn == 0) return 0;

        // approve router to spend tokens.
        _approve(address(this), address(router), amountIn);

        // swap the whole amount to eth.
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = router.WETH();

        uint256 originalETHbalance = address(this).balance;

        router.swapExactTokensForETHSupportingFeeOnTransferTokens(amountIn, amountOutMin, path, to, block.timestamp);

        return address(this).balance - originalETHbalance;
    }

    /**
     * Swap amount of ETH for reward tokens to address and return the amount received.
     */
    function _swapETHToRewardV3(address to, uint256 amountIn, uint256 amountOutMinimum) private returns (uint256) {
        // return 0 if no amount given.
        if (amountIn == 0) return 0;

        // build the swap parameter.
        ISwapRouter.ExactInputSingleParams memory params = ISwapRouter.ExactInputSingleParams({
            tokenIn: router.WETH(),
            tokenOut: address(rewardToken),
            fee: poolFee,
            recipient: to,
            deadline: block.timestamp,
            amountIn: amountIn,
            amountOutMinimum: amountOutMinimum,
            sqrtPriceLimitX96: 0
        });

        // execute the swap and return the number of received tokens.
        return swapRouter.exactInputSingle{value: amountIn}(params);
    }

    receive() external payable {}
}

/**
 * Useful Links:
 * 
 * Website: https://taopad.io/
 * X: https://x.com/TaoPadX
 * 
 * Expanding The Tao Ecosystem.
 * $TAOPAD holders receive $wTAO
 * 
 *
 */

/// @title Taopad
/// @author @niera26
/// @notice buy and sell tax on this token with rewardToken as wTao
/// @notice source: https://github.com/taopad/taopad-contracts
contract Taopad is ERC20Rewards {
    constructor() ERC20Rewards("Taopad", "TPAD", 1e6) {}
}

{
  "compilationTarget": {
    "Taopad.sol": "Taopad"
  },
  "evmVersion": "paris",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}