// File: /contracts/Platform/DAO/DaoFactory.sol



// SPDX-License-Identifier: MIT

import {DaoToken} from "./DaoToken.sol";
import {IERC20Dao} from "./interfaces/IERC20Dao.sol";
import {Pausable} from "../../Pausable.sol";
import {IDAOJoin} from "./interfaces/IDAOJoin.sol";

pragma solidity ^0.8.0;

/**
 * @author MetaPlayerOne DAO
 * @title DaoFactory
 * @notice Contract which manages daos in MetaPlayerOne.
 */
contract DaoFactory is Pausable {
    struct Dao { string name; string symbol; address owner_of; uint256 amount; uint256 limit; uint256 price; address token_address; }

    mapping(address => Dao) private _dao_by_contract;
    mapping(address => address[]) private _daos_by_owner;
    mapping(address => address) private _owner_by_dao;
    mapping(address => bool) private _is_activated;

    /**
    * @dev setup owner of this contract.
    */
    constructor (address owner_of_) Pausable(owner_of_) {}
    
    /**
    * @dev emits when new dao has been created or added to DaoFactory.
    */
    event daoCreated(string name, string symbol, address owner_of, uint256 presale, uint256 limit, uint256 price, address token_address, address join_address, bool created);

    /**
    * @dev function which creates dao with params.
    * @param name name of ERC20 which you want to add to DaoFactory.
    * @param symbol symbol of ERC20 which you want to add to DaoFactory.
    * @param presale presale of ERC20 which you want to add to DaoFactory.
    * @param limit limit of ERC20 which you want to add to DaoFactory.
    * @param price mint price of ERC20 which you want to add to DaoFactory.
    */
    function createDao(string memory name, string memory symbol, uint256 presale, uint256 limit, uint256 price) public notPaused {
        DaoToken token = new DaoToken(name, symbol, msg.sender, presale, limit, price);
        address join;
        try token.limit() { join = IDAOJoin(address(token)).joinAddress(); } catch {} 
        address token_address = address(token);
        _dao_by_contract[token_address] = Dao(name, symbol, msg.sender, presale, limit, price, token_address);
        _daos_by_owner[msg.sender].push(token_address);
        _owner_by_dao[token_address] = msg.sender;
        _is_activated[token_address] = true;
        emit daoCreated(name, symbol, msg.sender, presale, limit, price, token_address, join, true);
    }

    /**
    * @dev function which creates dao with params.
    * @param token_address token address of ERC20 which you want to add to DaoFactory.
    */
    function addDao(address token_address) public notPaused {
        require(!_is_activated[token_address], "Dao is already activated");
        IERC20Dao token = IERC20Dao(token_address);
        uint256 limit = 0;
        uint256 presale = 0;
        uint256 price = 0;
        try token.limit() { limit = token.limit(); } catch {}
        try token.presale() { presale = token.presale(); } catch {}
        try token.price() { price = token.price(); } catch {}
        _dao_by_contract[token_address] = Dao(token.name(), token.symbol(), msg.sender, presale, limit, price, token_address);
        _daos_by_owner[msg.sender].push(token_address);
        _owner_by_dao[token_address] = msg.sender;
        _is_activated[token_address] = true;
        emit daoCreated(token.name(), token.symbol(), msg.sender, presale, limit, price, token_address, address(0), false);
    }

    /**
    * @dev function which creates dao with params.
    * @param owner_of address of user, which daos should be returned
    * @return address list of dao addresses which this user register
    */
    function getDaosByOwner(address owner_of) public view returns (address[] memory) {
        return _daos_by_owner[owner_of];
    }

    /**
    * @dev function which creates dao with params.
    * @param dao_address includes name of project, project description and project banner and project logo
    * @return owner_of returns owner of requested dao.
    */
    function getDaoOwner(address dao_address) public view returns (address) {
        return _owner_by_dao[dao_address];
    }
}

// File: /contracts/Platform/DAO/interfaces/IERC20Dao.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

interface IERC20Dao {
    function name() external view returns (string memory);

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

    function price() external view returns (uint256);

    function limit() external view returns (uint256);

    function presale() external view returns (uint256);
}

// File: /contracts/Platform/DAO/interfaces/IDAOJoin.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

interface IDAOJoin {
    function joinAddress() external returns(address);
}

// File: /contracts/Platform/DAO/JoinDAOContract.sol




// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {ReentrancyGuard} from "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import {Pausable} from "../../Pausable.sol";

contract JoinDAOContract is Pausable, ReentrancyGuard {
    address private _token_address;
    uint256 private _price;

    constructor(address token_address_, uint256 price_, address owner_of_) Pausable(owner_of_) {
        _token_address = token_address_;
        _price = price_;
    }

    event poolCreated(address token_address, uint256 price, address creator);
    event priceEdited(address token_address, uint256 price);
    event ownerChanged(address token_address, address owner_of);
    event bought(address token_address, uint256 amount, uint256 amount_paid);

    function buy(uint256 amount_) public payable nonReentrant {
        require(msg.value >= _price * amount_ / 1 ether, "Not enough funds send");
        IERC20(_token_address).transfer(msg.sender, amount_);
        payable(_owner_of).send(msg.value);
        emit bought(_token_address, amount_, msg.value);
    }

    function removeLiquidity(address token_address_) public {
        require(_owner_of == msg.sender, "Permission denied");
        IERC20(token_address_).transfer(msg.sender, IERC20(token_address_).balanceOf(address(this)));
    }

    function setPrice(address token_address_, uint256 price_) public {
        require(_owner_of == msg.sender, "Permission denied");
        emit priceEdited(token_address_, price_);
    }

    function setTokenOwner(address token_address_, address owner_of_) public {
        require(_owner_of == msg.sender, "Permission denied");
        _owner_of = owner_of_;
        emit ownerChanged(token_address_, owner_of_);
    }
}
// File: /contracts/Platform/DAO/DaoToken.sol



// SPDX-License-Identifier: MIT

import {IERC20,ERC20Burnable,ERC20} from "@openzeppelin/contracts/token/ERC20/extensions/ERC20Burnable.sol";
import {Pausable} from "../../Pausable.sol";
import {JoinDAOContract} from "./JoinDAOContract.sol";
import {ReentrancyGuard} from "@openzeppelin/contracts/security/ReentrancyGuard.sol";

pragma solidity ^0.8.0;

contract DaoToken is ERC20Burnable, Pausable, ReentrancyGuard {
    uint256 private _limit;
    uint256 private _price;
    address private _join_contract_address;

    constructor(string memory name, string memory symbol, address owner_of, uint256 presale_, uint256 limit_, uint256 price_) ERC20(name, symbol) Pausable(owner_of) {
        if (limit_ > 0) {
            require(limit_ >= presale_, "Limit overrized");
            JoinDAOContract join = new JoinDAOContract(address(this), price_, owner_of);
            _mint(address(join), limit_ - presale_);
            _join_contract_address = address(join);
        }
        if (presale_ > 0) {
            _mint(owner_of, presale_);
        }
        _limit = limit_;
        _price = price_;
    }

    function mint(uint256 amount_) public payable notPaused nonReentrant {
        require(_limit == 0, "Permission denied");
        if (_price > 0) {
            require(msg.value >= (_price * amount_) / 1 ether);
            payable(_owner_of).transfer(msg.value);
        }
        _mint(msg.sender, amount_);
    }

    function setPrice(uint256 price_) public {
        require(msg.sender == _owner_of, "Permissin denied");
        _price = price_;
    }

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

    function limit() public view virtual returns (uint256) {
        return _limit;
    }

    function joinAddress() public view virtual returns (address) {
        return _join_contract_address;
    }
}

// File: /contracts/Pausable.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/**
 * @author MetaPlayerOne DAO
 * @title Pausable
 * @notice Contract which manages allocations in MetaPlayerOne.
 */
contract Pausable {
    address internal _owner_of;
    bool internal _paused = false;

    /**
    * @dev setup owner of this contract with paused off state.
    */
    constructor(address owner_of_) {
        _owner_of = owner_of_;
        _paused = false;
    }

    /**
    * @dev modifier which can be used on child contract for checking if contract services are paused.
    */
    modifier notPaused() {
        require(!_paused, "Contract is paused");
        _;
    }

    /**
    * @dev function which setup paused variable.
    * @param paused_ new boolean value of paused condition.
    */
    function setPaused(bool paused_) external {
        require(_paused == paused_, "Param has been asigned already");
        require(_owner_of == msg.sender, "Permission address");
        _paused = paused_;
    }

    /**
    * @dev function which setup owner variable.
    * @param owner_of_ new owner of contract.
    */
    function setOwner(address owner_of_) external {
        require(_owner_of == msg.sender, "Permission address");
        _owner_of = owner_of_;
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (utils/Context.sol)

pragma solidity ^0.8.0;

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

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

// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
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);
}

// File: @openzeppelin/contracts/token/ERC20/extensions/ERC20Burnable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (token/ERC20/extensions/ERC20Burnable.sol)

pragma solidity ^0.8.0;

import "../ERC20.sol";
import "../../../utils/Context.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 `amount` tokens from the caller.
     *
     * See {ERC20-_burn}.
     */
    function burn(uint256 amount) public virtual {
        _burn(_msgSender(), amount);
    }

    /**
     * @dev Destroys `amount` 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
     * `amount`.
     */
    function burnFrom(address account, uint256 amount) public virtual {
        uint256 currentAllowance = allowance(account, _msgSender());
        require(currentAllowance >= amount, "ERC20: burn amount exceeds allowance");
        unchecked {
            _approve(account, _msgSender(), currentAllowance - amount);
        }
        _burn(account, amount);
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

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

    /**
     * @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);
}

// File: @openzeppelin/contracts/token/ERC20/ERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (token/ERC20/ERC20.sol)

pragma solidity ^0.8.0;

import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";

/**
 * @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}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * 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.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;

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

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * 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 override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override 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 value {ERC20} uses, unless this function is
     * 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 override returns (uint8) {
        return 18;
    }

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

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

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

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

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        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}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);

        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        unchecked {
            _approve(sender, _msgSender(), currentAllowance - amount);
        }

        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(_msgSender(), spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `sender` to `recipient`.
     *
     * 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.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[sender] = senderBalance - amount;
        }
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, amount);

        _afterTokenTransfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
        }
        _totalSupply -= amount;

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` 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.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

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

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

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

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

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

        _;

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