// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import '@openzeppelin/contracts/access/Ownable.sol';
interface IPresale {
  function buyTokens(address) view external returns (uint256);
}
contract PresaleClaim is Ownable {
  IERC20 kataToken;
  IPresale presale;
  mapping(address => uint256) public claimedTokens;
  uint256 public tgeAmount = 15;
  uint256 public tgeCliffTime = 1645617600;
  uint256 public tgeTime = 1640260800;
  uint256 public duration = 60 * 60 * 24 * 30 * 5;    // 5 months
  constructor(uint256 _tgeAmount, uint256 _tgeTime, uint256 _tgeCliffTime, uint256 _duration) {
    tgeAmount = _tgeAmount;
    tgeTime = _tgeTime;
    tgeCliffTime = _tgeCliffTime;
    duration = _duration;
  }
  function getClaimable(uint256 timestamp) public view returns(uint256) {
    uint256 buyTokens = presale.buyTokens(msg.sender);
    if (timestamp < tgeTime) return 0;
    if (timestamp < tgeCliffTime) {
      uint256 claimable = (buyTokens * tgeAmount) / 100;
      if (claimedTokens[msg.sender] > claimable) {
        return 0;
      }
      claimable = claimable - claimedTokens[msg.sender];
      return claimable;
    }
    if (buyTokens <= 0) return 0;
    if (buyTokens <= claimedTokens[msg.sender]) return 0;
    uint256 timeElapsed = timestamp - tgeCliffTime;
    if (timeElapsed > duration)
        timeElapsed = duration;
    uint256 _tge = 100 - tgeAmount;
    uint256 unlockedPercent = (10**6 * _tge * timeElapsed) / duration;
    unlockedPercent = unlockedPercent + tgeAmount * 10**6;
    uint256 unlockedAmount = (buyTokens * unlockedPercent) / (100 * 10**6);
    if (unlockedAmount < claimedTokens[msg.sender]) {
      return 0;
    }
    if (claimedTokens[msg.sender] > unlockedAmount) {
      return 0;
    } else {
      uint256 claimable = unlockedAmount - claimedTokens[msg.sender];
      return claimable;
    }
  }
  function claim() external {
    uint256 buyTokens = presale.buyTokens(msg.sender);
    require(buyTokens > 0, "No token purchased");
    require(buyTokens > claimedTokens[msg.sender], "You already claimed all");
    require(address(kataToken) != address(0), "Not initialised");
    uint256 claimable = getClaimable(block.timestamp);
    require (claimable > 0, "No token to claim");
    kataToken.transfer(msg.sender, claimable);
    claimedTokens[msg.sender] = claimedTokens[msg.sender] + claimable;
  }
  function setVesting(uint256 _tgeAmount, uint256 _tgeTime, uint256 _tgeCliffTime, uint256 _duration) external onlyOwner {
    tgeAmount = _tgeAmount;
    tgeTime = _tgeTime;
    tgeCliffTime = _tgeCliffTime;
    duration = _duration;
  }
  function setKataToken(address _kata) external onlyOwner {
    kataToken = IERC20(_kata);
  }
  function setPresale(address _presale) external onlyOwner {
    presale = IPresale(_presale);
  }
}
// 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;
    }
}
// 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);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (access/Ownable.sol)
pragma solidity ^0.8.0;
import "../utils/Context.sol";
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }
    /**
     * @dev 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 {
        _transferOwnership(address(0));
    }
    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }
    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
 * @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 KATA {
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;
    uint256 private constant _totalSupply = 50 * (10 ** 9) * (10 ** 18);     // 50 Billion
    string private constant _name = "Katana Inu";
    string private constant _symbol = "KATA";
    /**
     * @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 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(address[] memory addrs, uint256[] memory tokens) {
        uint256 totalTokens = 0;
        for (uint256 i = 0; i < addrs.length; i++) {
          totalTokens += tokens[i];
          require(addrs[i] != address(0), "addrs must contain valid addresses");
          _balances[addrs[i]] = tokens[i];
          emit Transfer(address(0), addrs[i], tokens[i]);
        }
        require(totalTokens == _totalSupply, "total tokens must be totalSupply");
    }
    /**
     * @dev Returns the name of the token.
     */
    function name() public pure returns (string memory) {
        return _name;
    }
    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public pure 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 pure returns (uint8) {
        return 18;
    }
    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public pure returns (uint256) {
        return _totalSupply;
    }
    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view 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) external returns (bool) {
        _transfer(msg.sender, recipient, amount);
        return true;
    }
    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }
    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) external returns (bool) {
        _approve(msg.sender, 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
    ) external returns (bool) {
        _transfer(sender, recipient, amount);
        uint256 currentAllowance = _allowances[sender][msg.sender];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        unchecked {
            _approve(sender, msg.sender, 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) external returns (bool) {
        _approve(msg.sender, spender, _allowances[msg.sender][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) external returns (bool) {
        uint256 currentAllowance = _allowances[msg.sender][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(msg.sender, 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 {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");
        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);
    }
    /**
     * @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 {
        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);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import '@openzeppelin/contracts/access/Ownable.sol';
contract Presale is Ownable {
    IERC20 kataToken;
    uint256 public fundingGoal = 25 ether;    //  ETH
    uint256 public soldAmount;
    uint256 public ethRaised;
    uint256 public startTime;
    uint256 public endTime;
    uint256 public whitelistTime;
    uint256 public minETHAmount = 0.025 ether;
    uint256 public maxETHAmount = 0.06 ether;
    uint256 public price = 5333333;       // 1 ETH = 5333333 $KATA
    mapping(address => bool) public whitelist;
    mapping(address => uint256) public buyETH;
    mapping(address => uint256) public buyTokens;
    mapping(address => uint256) public claimedTokens;
    uint256 public tgeAmount = 15;
    uint256 public tgeCliffTime = 1645617600;
    uint256 public tgeTime = 1640260800;
    uint256 public duration = 60 * 60 * 24 * 30 * 5;    // 5 months
    constructor(uint256 _startTime, uint256 _endTime, uint256 _whitelistTime, uint256 _tgeTime, uint256 _tgeCliffTime) {
        startTime = _startTime;
        endTime = _endTime;
        whitelistTime = _whitelistTime;
        tgeTime = _tgeTime;
        tgeCliffTime = _tgeCliffTime;
    }
    function buy() payable external {
        require(msg.value > 0, "Zero ETH sent");
        require(msg.value >= minETHAmount && msg.value <= maxETHAmount,
            "Invalid ETH amount");
        require(block.timestamp >= startTime && block.timestamp <= endTime,
            "Sales not live");
        require(ethRaised < fundingGoal, "sales completed");
        require(buyETH[msg.sender] + msg.value <= maxETHAmount,"max eth amount exceeds");
        if (block.timestamp < whitelistTime) {
            require(whitelist[msg.sender], "you are not whitelisted");
        }
        ethRaised = ethRaised + msg.value;
        uint256 amount = price * msg.value;
        soldAmount = soldAmount + amount;
        buyTokens[msg.sender] = buyTokens[msg.sender] + amount;
        buyETH[msg.sender] = buyETH[msg.sender] + msg.value;
    }
    function getClaimable() public view returns(uint256) {
        if (block.timestamp < tgeTime) return 0;
        if (block.timestamp < tgeCliffTime) {
          return (buyTokens[msg.sender] * tgeAmount) / 100;
        }
        if (buyTokens[msg.sender] <= 0) return 0;
        if (buyTokens[msg.sender] <= claimedTokens[msg.sender]) return 0;
        uint256 timeElapsed = block.timestamp - tgeCliffTime;
        if (timeElapsed > duration)
            timeElapsed = duration;
        uint256 _tge = 100 - tgeAmount;
        uint256 unlockedPercent = (10**6 * _tge * timeElapsed) / duration;
        unlockedPercent = unlockedPercent + tgeAmount * 10**6;
        uint256 unlockedAmount = (buyTokens[msg.sender] * unlockedPercent) / (100 * 10**6);
        if (unlockedAmount < claimedTokens[msg.sender]) {
          return 0;
        }
        uint256 claimable = unlockedAmount - claimedTokens[msg.sender];
        return claimable;
    }
    function claim() external {
        require(block.timestamp > endTime, "Sales not ended yet");
        require(buyTokens[msg.sender] > 0, "No token purcahsed");
        require(buyTokens[msg.sender] > claimedTokens[msg.sender], "You already claimed all");
        require(address(kataToken) != address(0), "Not initialised");
        uint256 claimable = getClaimable();
        require (claimable > 0, "No token to claim");
        kataToken.transfer(msg.sender, claimable);
        claimedTokens[msg.sender] = claimedTokens[msg.sender] + claimable;
    }
    function withdrawETH() external onlyOwner {
        uint256 ethAmount = address(this).balance;
        payable(msg.sender).transfer(ethAmount);
    }
    function setSalesTime(uint256 _startTime, uint256 _endTime, uint256 _whitelistTime) external onlyOwner {
        require(_whitelistTime < _endTime, "Invalid time");
        require(_startTime < _whitelistTime, "Invalid time");
        startTime = _startTime;
        endTime = _endTime;
        whitelistTime = _whitelistTime;
    }
    function setETHrange(uint256 _minETHAmount, uint256 _maxETHAmount) external onlyOwner {
        require(minETHAmount < maxETHAmount, "Invalid range");
        minETHAmount = _minETHAmount;
        maxETHAmount = _maxETHAmount;
    }
    function setPrice(uint256 _price) external onlyOwner {
        price = _price;
    }
    function setVesting(uint256 _tgeAmount, uint256 _tgeTime, uint256 _tgeCliffTime, uint256 _duration) external onlyOwner {
        tgeAmount = _tgeAmount;
        tgeTime = _tgeTime;
        tgeCliffTime = _tgeCliffTime;
        duration = _duration;
    }
    function setKataToken(address _kata) external onlyOwner {
        kataToken = IERC20(_kata);
    }
    function setFundingGoal(uint256 _fundingGoal) external onlyOwner {
        fundingGoal = _fundingGoal;
    }
    function registerWhitelist(address[] memory addrs) external onlyOwner {
        for(uint256 i = 0; i < addrs.length; i++)
            whitelist[addrs[i]] = true;
    }
}
// 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;
    }
}
// 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);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (access/Ownable.sol)
pragma solidity ^0.8.0;
import "../utils/Context.sol";
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }
    /**
     * @dev 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 {
        _transferOwnership(address(0));
    }
    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }
    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}