// File: /contracts/StakingPoolModWithdraw.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

import "./TokenERC20.sol";
import "./StakingPoolFactory.sol";
import "./RewardManager.sol";

contract StakingPoolModWithdraw is Context, Ownable, ReentrancyGuard {

    mapping (address => uint256) private stakes;
    mapping (address => uint256) private stakeTimes;

    uint256 public stakedTotal;
    uint256 public maturityDays;
    uint256 public launchTime;
    uint256 public closingTime;
    uint256 public poolSize;
    uint256 public poolApy;
    TokenERC20 public tokenERC20;
    StakingPoolFactory public poolFactory;
    RewardManager public rewardManager;

    uint256 interval = 86400;

    event Staked(address indexed _staker, uint256 _requestedAmount, uint256 _stakedAmount);
    event PaidOut(address indexed _staker, uint256 _reward);
    event Refunded(address indexed _staker, uint256 _amount);

    constructor (
        TokenERC20 _tokenERC20,
        StakingPoolFactory _poolFactory,
        RewardManager _rewardManager,
        uint256 _maturityDays,
        uint256 _launchTime,
        uint256 _closingTime,
        uint256 _poolSize,
        uint256 _poolApy
    ) {
        tokenERC20 = _tokenERC20;
        poolFactory = _poolFactory;
        rewardManager = _rewardManager;

        require(_maturityDays > 0, "Staking Pool: zero maturity days");

        maturityDays = _maturityDays;

        require(_launchTime > 0, "Staking Pool: zero staking start time");
        if (_launchTime < block.timestamp) {
            launchTime = block.timestamp;
        } else {
            launchTime = _launchTime;
        }

        require(_closingTime > _launchTime, "Staking Pool: closing time must be after launch time");
        closingTime = _closingTime;

        require(_poolSize > 0, "Staking Pool: pool size must be positive");
        poolSize = _poolSize;

        require(_poolApy >= 0, "Staking Pool: pool apy must be positive");
        poolApy = _poolApy;
    }

    function stakeOf(address account) external view returns (uint256) {
        return stakes[account];
    }

    function stakeTimeOf(address account) external view returns (uint256) {
        return stakeTimes[account];
    }

    function getRewards(address account) external view returns (uint256) {
        if (block.timestamp > stakeTimes[account] + (maturityDays * interval)) {
            return stakes[account] * poolApy * maturityDays / 36000;
        }

        return 0;
    }

    function stake(uint256 amount)
        external
        _positive(amount)
        _realAddress(_msgSender())
        _after(launchTime)
        _before(closingTime)
        _hasAllowance(_msgSender(), amount)
        returns (bool)
    {
        address staker = _msgSender();
        uint256 remaining = amount;
        if (remaining > (poolSize - stakedTotal)) {
            remaining = poolSize - stakedTotal;
        }
        // These requires are not necessary, because it will never happen, but won't hurt to double check
        // this is because stakedTotal is only modified in this method during the staking period
        require(remaining > 0, "Staking Pool: Pool is filled");
        require((remaining + stakedTotal) <= poolSize, "Staking Pool: this will increase staking amount pass the cap");

        if (!_payMe(staker, remaining)) {
            return false;
        }
        emit Staked(staker, amount, remaining);

        if (remaining < amount) {
            // Return the unstaked amount to sender (from allowance)
            uint256 refund = amount - remaining;
            if (_payTo(staker, staker, refund)) {
                emit Refunded(staker, refund);
            }
        }

        // Transfer is completed
        stakedTotal = stakedTotal + remaining;
        stakes[staker] = stakes[staker] + remaining;
        stakeTimes[staker] = block.timestamp;

        return true;
    }

    function withdraw()
        external
        nonReentrant
        _realAddress(_msgSender())
    {
        address staker = _msgSender();

        require(stakes[staker] > 0, "Zero staked SpellFire");

        uint256 amount = stakes[staker];

        require(block.timestamp > stakeTimes[staker] + (maturityDays * interval));
            uint256 reward = amount * poolApy * maturityDays / 36000;
            _payDirect(staker, amount);
            rewardManager.rewardUser(staker, reward);
            PaidOut(staker, reward);
            stakes[staker] = 0;
    }

    function _payMe(address payer, uint256 amount)
        private
        returns (bool) 
    {
        return _payTo(payer, address(this), amount);
    }

    function _payTo(address allower, address receiver, uint256 amount)
        _hasAllowance(allower, amount)
        private
        returns (bool) 
    {
        // Request to transfer amount from the contract to receiver.
        // contract does not own the funds, so the allower must have added allowance to the contract
        // Allower is the original owner.
        return tokenERC20.transferFrom(allower, receiver, amount);
    }

    function _payDirect(address to, uint256 amount)
        private
        _positive(amount)
        returns (bool) 
    {
        return tokenERC20.transfer(to, amount);
    }

    modifier _realAddress(address addr) {
        require(addr != address(0), "Staking Pool: zero address");
        _;
    }

    modifier _positive(uint256 amount) {
        require(amount >= 0, "Staking Pool: negative amount");
        _;
    }

    modifier _after(uint eventTime) {
        require(block.timestamp >= eventTime, "Staking Pool: bad timing for the request");
        _;
    }

    modifier _before(uint eventTime) {
        require(block.timestamp < eventTime, "Staking Pool: bad timing for the request");
        _;
    }

    modifier _hasAllowance(address allower, uint256 amount) {
        // Make sure the allower has provided the right allowance.
        uint256 ourAllowance = tokenERC20.allowance(allower, address(this));
        require(amount <= ourAllowance, "Staking Pool: Make sure to add enough allowance");
        _;
    }
}
// File: /contracts/TokenERC20.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract TokenERC20 is ERC20('Mixsome', 'SOME') {
    constructor () {
        _mint(msg.sender, 93777508090614882400000000);
    }
}
// File: /contracts/StakingPoolFactory.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;

import "./TokenERC20.sol";
import "./PoolCreator.sol";
import "./StakingPool.sol";
import "./RewardManager.sol";

contract StakingPoolFactory is PoolCreator {
    TokenERC20 public tokenERC20;
    RewardManager public rewardManager;

    event PoolCreated(
        address indexed pool,
        uint256 maturityDays,
        uint256 launchTime,
        uint256 poolSize,
        uint256 poolApy
    );

    constructor(TokenERC20 _tokenERC20, RewardManager _rewardManager) {
        tokenERC20 = _tokenERC20;
        rewardManager = _rewardManager;
    }

    function create(
        uint256 maturityDays,
        uint256 launchTime,
        uint256 closingTime,
        uint256 poolSize,
        uint256 poolApy
    ) public onlyPoolCreator returns (address) {
        address newPool =
            address(
                new StakingPool(
                    tokenERC20,
                    this,
                    rewardManager,
                    maturityDays,
                    launchTime,
                    closingTime,
                    poolSize,
                    poolApy
                )
            );

        emit PoolCreated(newPool, maturityDays, launchTime, poolSize, poolApy);

        rewardManager.addPool(newPool);

        return newPool;
    }
}
// File: /contracts/StakingPool.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

import "./TokenERC20.sol";
import "./StakingPoolFactory.sol";
import "./RewardManager.sol";

contract StakingPool is Context, Ownable, ReentrancyGuard {

    mapping (address => uint256) private stakes;
    mapping (address => uint256) private stakeTimes;

    uint256 public stakedTotal;
    uint256 public maturityDays;
    uint256 public launchTime;
    uint256 public closingTime;
    uint256 public poolSize;
    uint256 public poolApy;
    TokenERC20 public tokenERC20;
    StakingPoolFactory public poolFactory;
    RewardManager public rewardManager;

    uint256 interval = 86400;

    event Staked(address indexed _staker, uint256 _requestedAmount, uint256 _stakedAmount);
    event PaidOut(address indexed _staker, uint256 _reward);
    event Refunded(address indexed _staker, uint256 _amount);

    constructor (
        TokenERC20 _tokenERC20,
        StakingPoolFactory _poolFactory,
        RewardManager _rewardManager,
        uint256 _maturityDays,
        uint256 _launchTime,
        uint256 _closingTime,
        uint256 _poolSize,
        uint256 _poolApy
    ) {
        tokenERC20 = _tokenERC20;
        poolFactory = _poolFactory;
        rewardManager = _rewardManager;

        require(_maturityDays > 0, "Staking Pool: zero maturity days");

        maturityDays = _maturityDays;

        require(_launchTime > 0, "Staking Pool: zero staking start time");
        if (_launchTime < block.timestamp) {
            launchTime = block.timestamp;
        } else {
            launchTime = _launchTime;
        }

        require(_closingTime > _launchTime, "Staking Pool: closing time must be after launch time");
        closingTime = _closingTime;

        require(_poolSize > 0, "Staking Pool: pool size must be positive");
        poolSize = _poolSize;

        require(_poolApy > 0, "Staking Pool: pool apy must be positive");
        poolApy = _poolApy;
    }

    function stakeOf(address account) external view returns (uint256) {
        return stakes[account];
    }

    function stakeTimeOf(address account) external view returns (uint256) {
        return stakeTimes[account];
    }

    function getRewards(address account) external view returns (uint256) {
        if (block.timestamp > stakeTimes[account] + (maturityDays * interval)) {
            return stakes[account] * poolApy * maturityDays / 36000;
        }

        return 0;
    }

    function stake(uint256 amount)
        external
        _positive(amount)
        _realAddress(_msgSender())
        _after(launchTime)
        _before(closingTime)
        _hasAllowance(_msgSender(), amount)
        returns (bool)
    {
        address staker = _msgSender();
        uint256 remaining = amount;
        if (remaining > (poolSize - stakedTotal)) {
            remaining = poolSize - stakedTotal;
        }
        // These requires are not necessary, because it will never happen, but won't hurt to double check
        // this is because stakedTotal is only modified in this method during the staking period
        require(remaining > 0, "Staking Pool: Pool is filled");
        require((remaining + stakedTotal) <= poolSize, "Staking Pool: this will increase staking amount pass the cap");

        if (!_payMe(staker, remaining)) {
            return false;
        }
        emit Staked(staker, amount, remaining);

        if (remaining < amount) {
            // Return the unstaked amount to sender (from allowance)
            uint256 refund = amount - remaining;
            if (_payTo(staker, staker, refund)) {
                emit Refunded(staker, refund);
            }
        }

        // Transfer is completed
        stakedTotal = stakedTotal + remaining;
        stakes[staker] = stakes[staker] + remaining;
        stakeTimes[staker] = block.timestamp;

        return true;
    }

    function withdraw()
        external
        nonReentrant
        _realAddress(_msgSender())
    {
        address staker = _msgSender();

        require(stakes[staker] > 0, "Zero staked Mixsome");

        uint256 amount = stakes[staker];
        stakes[staker] = 0;
        _payDirect(staker, amount);

        if (block.timestamp > stakeTimes[staker] + (maturityDays * interval)) {
            uint256 reward = amount * poolApy * maturityDays / 36000;
            rewardManager.rewardUser(staker, reward);
            PaidOut(staker, reward);
        }
    }

    function _payMe(address payer, uint256 amount)
        private
        returns (bool) 
    {
        return _payTo(payer, address(this), amount);
    }

    function _payTo(address allower, address receiver, uint256 amount)
        _hasAllowance(allower, amount)
        private
        returns (bool) 
    {
        // Request to transfer amount from the contract to receiver.
        // contract does not own the funds, so the allower must have added allowance to the contract
        // Allower is the original owner.
        return tokenERC20.transferFrom(allower, receiver, amount);
    }

    function _payDirect(address to, uint256 amount)
        private
        _positive(amount)
        returns (bool) 
    {
        return tokenERC20.transfer(to, amount);
    }

    modifier _realAddress(address addr) {
        require(addr != address(0), "Staking Pool: zero address");
        _;
    }

    modifier _positive(uint256 amount) {
        require(amount >= 0, "Staking Pool: negative amount");
        _;
    }

    modifier _after(uint eventTime) {
        require(block.timestamp >= eventTime, "Staking Pool: bad timing for the request");
        _;
    }

    modifier _before(uint eventTime) {
        require(block.timestamp < eventTime, "Staking Pool: bad timing for the request");
        _;
    }

    modifier _hasAllowance(address allower, uint256 amount) {
        // Make sure the allower has provided the right allowance.
        uint256 ourAllowance = tokenERC20.allowance(allower, address(this));
        require(amount <= ourAllowance, "Staking Pool: Make sure to add enough allowance");
        _;
    }
}
// File: /contracts/Roles.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;

/**
 * @title Roles
 * @dev Library for managing addresses assigned to a Role.
 */
library Roles {
    struct Role {
        mapping(address => bool) bearer;
    }

    /**
     * @dev Give an account access to this role.
     */
    function add(Role storage role, address account) internal {
        require(!has(role, account), "Roles: account already has role");
        role.bearer[account] = true;
    }

    /**
     * @dev Remove an account's access to this role.
     */
    function remove(Role storage role, address account) internal {
        require(has(role, account), "Roles: account does not have role");
        role.bearer[account] = false;
    }

    /**
     * @dev Check if an account has this role.
     * @return bool
     */
    function has(Role storage role, address account)
        internal
        view
        returns (bool)
    {
        require(account != address(0), "Roles: account is the zero address");
        return role.bearer[account];
    }
}
// File: /contracts/Rewarder.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;

import "@openzeppelin/contracts/utils/Context.sol";

import "./Roles.sol";

contract Rewarder is Context {
    using Roles for Roles.Role;

    event RewarderAdded(address indexed account);
    event RewarderRemoved(address indexed account);

    Roles.Role private _rewarders;

    constructor() {
        if (!isRewarder(_msgSender())) {
            _addRewarder(_msgSender());
        }
    }

    modifier onlyRewarder() {
        require(
            isRewarder(_msgSender()),
            "RewarderRole: caller does not have the Rewarder role"
        );
        _;
    }

    function isRewarder(address account) public view returns (bool) {
        return _rewarders.has(account);
    }

    function addRewarder(address account) public onlyRewarder {
        _addRewarder(account);
    }

    function renounceRewarder() public {
        _removeRewarder(_msgSender());
    }

    function _addRewarder(address account) internal {
        _rewarders.add(account);
        emit RewarderAdded(account);
    }

    function _removeRewarder(address account) internal {
        _rewarders.remove(account);
        emit RewarderRemoved(account);
    }
}
// File: /contracts/RewardManager.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "./TokenERC20.sol";
import "./Operator.sol";
import "./Rewarder.sol";

contract RewardManager is Context, Ownable, Operator, Rewarder {
    TokenERC20 tokenERC20;
    address operator;

    constructor(TokenERC20 _tokenERC20) {
        tokenERC20 = _tokenERC20;
    }

    function setOperator(address _newOperator) public onlyOwner {
        require(_newOperator != address(0));

        addOperator(_newOperator);
    }

    function addPool(address _poolAddress) public onlyOperator {
        require(_poolAddress != address(0));

        addRewarder(_poolAddress);
    }

    function rewardUser(address _user, uint256 _amount) public onlyRewarder {
        require(_user != address(0));

        tokenERC20.transfer(_user, _amount);
    }
}
// File: /contracts/PoolCreator.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;

import "@openzeppelin/contracts/utils/Context.sol";

import "./Roles.sol";

contract PoolCreator is Context {
    using Roles for Roles.Role;

    event PoolCreatorAdded(address indexed account);
    event PoolCreatorRemoved(address indexed account);

    Roles.Role private _poolCreators;

    constructor() {
        if (!isPoolCreator(_msgSender())) {
            _addPoolCreator(_msgSender());
        }
    }

    modifier onlyPoolCreator() {
        require(
            isPoolCreator(_msgSender()),
            "PoolCreatorRole: caller does not have the PoolCreator role"
        );
        _;
    }

    function isPoolCreator(address account) public view returns (bool) {
        return _poolCreators.has(account);
    }

    function addPoolCreator(address account) public onlyPoolCreator {
        _addPoolCreator(account);
    }

    function renouncePoolCreator() public {
        _removePoolCreator(_msgSender());
    }

    function _addPoolCreator(address account) internal {
        _poolCreators.add(account);
        emit PoolCreatorAdded(account);
    }

    function _removePoolCreator(address account) internal {
        _poolCreators.remove(account);
        emit PoolCreatorRemoved(account);
    }
}
// File: /contracts/Operator.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;

import "@openzeppelin/contracts/utils/Context.sol";

import "./Roles.sol";

contract Operator is Context {
    using Roles for Roles.Role;

    event OperatorAdded(address indexed account);
    event OperatorRemoved(address indexed account);

    Roles.Role private _operators;

    constructor() {
        if (!isOperator(_msgSender())) {
            _addOperator(_msgSender());
        }
    }

    modifier onlyOperator() {
        require(
            isOperator(_msgSender()),
            "OperatorRole: caller does not have the Operator role"
        );
        _;
    }

    function isOperator(address account) public view returns (bool) {
        return _operators.has(account);
    }

    function addOperator(address account) public onlyOperator {
        _addOperator(account);
    }

    function renounceOperator() public {
        _removeOperator(_msgSender());
    }

    function _addOperator(address account) internal {
        _operators.add(account);
        emit OperatorAdded(account);
    }

    function _removeOperator(address account) internal {
        _operators.remove(account);
        emit OperatorRemoved(account);
    }
}
// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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



// SPDX-License-Identifier: MIT

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/IERC20.sol



// SPDX-License-Identifier: MIT

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

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

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 make 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;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}