// File: /contracts/TravelCare.sol



// SPDX-License-Identifier: Unlicensed
pragma solidity 0.8.11;

import { ERC20 } from "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import { Ownable } from "@openzeppelin/contracts/access/Ownable.sol";


contract TravelCare is
    Ownable,
    ERC20
{
    uint256 public immutable CAP;

    address public marketingWallet;
    uint256 public marketingFee;
    uint256 public burningFee;
    uint256 public maxTxAmount;

    mapping(address => bool) public isExcludedFromFee;

    enum RewardType {
        None,
        Pink_Flamingo,
        Indigo_Bunting,
        Purple_Martin,
        Golden_Eagle,
        Arctic_Tern
    }

    struct RewardTypeInfo {
        uint256 minDuration;
        uint256 minBalance;
    }

    mapping(RewardType => RewardTypeInfo) public categories;

    mapping(address => mapping(RewardType => uint256)) public userToRewardTypeTimestamp;

    constructor(
        address _marketingWallet,
        uint256 _marketingFee,
        uint256 _burningFee,
        uint256 _maxTxAmount
    ) ERC20("TravelCare", "TRAVEL") {
        marketingWallet = _marketingWallet;
        marketingFee = _marketingFee;
        burningFee = _burningFee;
        maxTxAmount = _maxTxAmount;

        isExcludedFromFee[address(this)] = true;
        isExcludedFromFee[msg.sender] = true;

        CAP = 210_000_000 * (10 ** decimals());

        categories[RewardType.Pink_Flamingo] =
            RewardTypeInfo(0, 1000 * (10 ** decimals()));

        categories[RewardType.Indigo_Bunting] =
            RewardTypeInfo(30 days, 11_000 * (10 ** decimals()));

        categories[RewardType.Purple_Martin] =
            RewardTypeInfo(60 days, 63_000 * (10 ** decimals()));

        categories[RewardType.Golden_Eagle] =
            RewardTypeInfo(120 days, 210_000 * (10 ** decimals()));

        categories[RewardType.Arctic_Tern] =
            RewardTypeInfo(180 days, 840_000 * (10 ** decimals()));

        _mint(
            msg.sender,
            CAP
        );
    }

    function getUserRewardStatus(address account)
        public
        view
        returns (RewardType)
    {
        mapping(RewardType => uint256) storage userRewardsToTimestamp = userToRewardTypeTimestamp[account];

        if (
            userRewardsToTimestamp[RewardType.Arctic_Tern] != 0 &&
            (
                block.timestamp - userRewardsToTimestamp[RewardType.Arctic_Tern]
                >= categories[RewardType.Arctic_Tern].minDuration
            )
        )
            return RewardType.Arctic_Tern;

        if (
            userRewardsToTimestamp[RewardType.Golden_Eagle] != 0 &&
            (
                block.timestamp - userRewardsToTimestamp[RewardType.Golden_Eagle]
                >= categories[RewardType.Golden_Eagle].minDuration
            )
        )
            return RewardType.Golden_Eagle;

        if (
            userRewardsToTimestamp[RewardType.Purple_Martin] != 0 &&
            (
                block.timestamp - userRewardsToTimestamp[RewardType.Purple_Martin]
                >= categories[RewardType.Purple_Martin].minDuration
            )
        )
            return RewardType.Purple_Martin;

        if (
            userRewardsToTimestamp[RewardType.Indigo_Bunting] != 0 &&
            (
                block.timestamp - userRewardsToTimestamp[RewardType.Indigo_Bunting]
                >= categories[RewardType.Indigo_Bunting].minDuration
            )
        )
            return RewardType.Indigo_Bunting;

        if (
            userRewardsToTimestamp[RewardType.Pink_Flamingo] != 0 &&
            (
                block.timestamp - userRewardsToTimestamp[RewardType.Pink_Flamingo]
                >= categories[RewardType.Pink_Flamingo].minDuration
            )
        )
            return RewardType.Pink_Flamingo;

        return RewardType.None;
    }

    receive() external payable {}

    function changeRewardRequirements(
        RewardType _rewardType,
        uint256 _newAmount,
        uint256 _newDuration
    ) external onlyOwner {
        require(
            uint8(_rewardType) > uint8(RewardType.None),
            "TravelCare::changeRewardRequirements: invalid reward type"
        );

        categories[_rewardType] = RewardTypeInfo(_newDuration, _newAmount);
    }

    function mint(address _to, uint256 _amount)
        external
        onlyOwner
    {
        require(
           totalSupply() + _amount <= CAP,
            "TravelCare::mint: minting exceeds CAP"
        );

        _mint(
            _to,
            _amount
        );
    }

    function burn(uint256 _amount) external {
        _burn(_msgSender(), _amount);
    }

    function burnFrom(address _from, uint256 _amount) external {
        uint256 currentAllowance = allowance(_from, _msgSender());
        _approve(
            _from,
            _msgSender(),
            currentAllowance - _amount
        );
        _burn(_from, _amount);
    }

    function excludeFromFee(address _account, bool exclude)
        external
        onlyOwner
    {
        isExcludedFromFee[_account] = exclude;
    }

    function setMarketingFee(uint256 _marketingFee)
        external
        onlyOwner
    {
        marketingFee = _marketingFee;
    }

    function setBurningFee(uint256 _burningFee)
        external
        onlyOwner
    {
        burningFee = _burningFee;
    }

    function setMaxTxAmount(uint256 _maxTxAmount)
        external
        onlyOwner
    {
        maxTxAmount = _maxTxAmount;
    }

    function withdrawBNB(uint256 _amount)
        external
        onlyOwner
    {
        payable(msg.sender).transfer(_amount);
    }

    function withdrawToken(address _token, uint256 _amount)
        external
        onlyOwner
    {
        IERC20(_token).transfer(msg.sender, _amount);
    }

    function setMarketingWallet(address _marketingWallet)
        external
        onlyOwner
    {
        marketingWallet = _marketingWallet;
    }

    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal override {
        require(
            sender != address(0),
            "ERC20::_transfer: transfer from the zero address"
        );

        require(
            recipient != address(0),
            "ERC20::_transfer: transfer to the zero address"
        );

        address _owner = owner();
        if (sender != _owner && recipient != _owner)
            require(
                amount <= maxTxAmount,
                "ERC20::_transfer: amount exceeds maxTxAmount"
            );

        bool takeFee = !isExcludedFromFee[sender] && !isExcludedFromFee[recipient];
        if (takeFee) {
            (
                uint256 burnFeeCollected,
                uint256 marketingFeeCollected
            ) = processFee(sender, amount);

            amount = amount
                - burnFeeCollected
                - marketingFeeCollected;
        }

        ERC20._transfer(
            sender,
            recipient,
            amount
        );
    }

    function processFee(address _account, uint256 _tokenAmount)
        private
        returns(
            uint256 burnFeeCollected,
            uint256 marketingFeeCollected
        )
    {
        burnFeeCollected = _tokenAmount * burningFee / 100;
        marketingFeeCollected = _tokenAmount * marketingFee / 100;

        _balances[_account] = _balances[_account]
            - burnFeeCollected
            - marketingFeeCollected;

        _totalSupply = _totalSupply - burnFeeCollected;
        _balances[marketingWallet] = _balances[marketingWallet] + marketingFeeCollected;

        return (
            burnFeeCollected,
            marketingFeeCollected
        );
    }

    function addEligibleRewards(address account) private {
        mapping(RewardType => uint256) storage userRewardsToTimestamp = userToRewardTypeTimestamp[account];
        uint256 balance = balanceOf(account);

        if (
            userRewardsToTimestamp[RewardType.Pink_Flamingo] == 0 &&
            balance >= categories[RewardType.Pink_Flamingo].minBalance
        )
            userRewardsToTimestamp[RewardType.Pink_Flamingo] = block.timestamp;

        if (
            userRewardsToTimestamp[RewardType.Indigo_Bunting] == 0 &&
            balance >= categories[RewardType.Indigo_Bunting].minBalance
        )
            userRewardsToTimestamp[RewardType.Indigo_Bunting] = block.timestamp;

        if (
            userRewardsToTimestamp[RewardType.Purple_Martin] == 0 &&
            balance >= categories[RewardType.Purple_Martin].minBalance
        )
            userRewardsToTimestamp[RewardType.Purple_Martin] = block.timestamp;

        if (
            userRewardsToTimestamp[RewardType.Golden_Eagle] == 0 &&
            balance >= categories[RewardType.Golden_Eagle].minBalance
        )
            userRewardsToTimestamp[RewardType.Golden_Eagle] = block.timestamp;

        if (
            userRewardsToTimestamp[RewardType.Arctic_Tern] == 0 &&
            balance >= categories[RewardType.Arctic_Tern].minBalance
        )
            userRewardsToTimestamp[RewardType.Arctic_Tern] = block.timestamp;
    }

    function removeOutstandingRewards(address account) private {
        mapping(RewardType => uint256) storage userRewardsToTimestamp = userToRewardTypeTimestamp[account];
        uint256 balance = balanceOf(account);

        if (
            userRewardsToTimestamp[RewardType.Pink_Flamingo] != 0 &&
            balance < categories[RewardType.Pink_Flamingo].minBalance
        )
            userRewardsToTimestamp[RewardType.Pink_Flamingo] = 0;

        if (
            userRewardsToTimestamp[RewardType.Indigo_Bunting] != 0 &&
            balance < categories[RewardType.Indigo_Bunting].minBalance
        )
            userRewardsToTimestamp[RewardType.Indigo_Bunting] = 0;

        if (
            userRewardsToTimestamp[RewardType.Purple_Martin] != 0 &&
            balance < categories[RewardType.Purple_Martin].minBalance
        )
            userRewardsToTimestamp[RewardType.Purple_Martin] = 0;

        if (
            userRewardsToTimestamp[RewardType.Golden_Eagle] != 0 &&
            balance < categories[RewardType.Golden_Eagle].minBalance
        )
            userRewardsToTimestamp[RewardType.Golden_Eagle] = 0;

        if (
            userRewardsToTimestamp[RewardType.Arctic_Tern] != 0 &&
            balance < categories[RewardType.Arctic_Tern].minBalance
        )
            userRewardsToTimestamp[RewardType.Arctic_Tern] = 0;
    }

    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal override {
        super._afterTokenTransfer(
            from,
            to,
            amount
        );

        if (from != address(0))
            removeOutstandingRewards(from);

        if (to != address(0))
            addEligibleRewards(to);
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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 v4.4.1 (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/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from,
        address to,
        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 (last updated v4.5.0) (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) internal _balances;

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

    uint256 internal _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:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, 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}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, 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}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, 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) {
        address owner = _msgSender();
        _approve(owner, spender, _allowances[owner][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) {
        address owner = _msgSender();
        uint256 currentAllowance = _allowances[owner][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, 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:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
        }
        _balances[to] += amount;

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, 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 Spend `amount` form the allowance of `owner` toward `spender`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - 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/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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);
    }
}