// File: contracts/johndoeR1.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.8.19;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Burnable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "./IUniswapV2Factory.sol";
import "./IUniswapV2Pair.sol";
import "./IUniswapV2Router01.sol";
import "./IUniswapV2Router02.sol";

contract Token is ERC20, ERC20Burnable, Ownable {

	address public xtaxAddress;
	uint16[3] public xtaxFees;

	mapping (address => bool) public isExcludedFromFees;

	uint16[3] public totalFees;
	bool private _swapping;

	// Disabled as the default and will be activated prior to the token launch.
	bool tradingActive = false;

	address addrOwner = 0x489Cec81305F6dDc71A11354b6286612aa21817c;
	address addrTaxes = 0xdf196D7F12C79c65fdAf5dEF71B290c78C8A79f9;
	address uniswapRouterV2 = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D;

	IUniswapV2Router02 public routerV2;
	address public pairV2;
	mapping (address => bool) public AMMPairs;
 
	event xtaxAddressUpdated(address xtaxAddress);
	event xtaxFeesUpdated(uint16 buyFee, uint16 sellFee, uint16 transferFee);
	event xtaxFeeSent(address recipient, uint256 amount);

	event ExcludeFromFees(address indexed account, bool isExcluded);

	event RouterV2Updated(address indexed routerV2);
	event AMMPairsUpdated(address indexed AMMPair, bool isPair);
 
	constructor()
		ERC20(unicode"John Doe", unicode"JOHN") 
	{
		// Taxes Buy & Sell 1%
		// No Transfer Fee
		xtaxAddressSetup(addrTaxes);
		xtaxFeesSetup(100, 100, 0);

		_excludeFromFees(addrOwner, true);
		_excludeFromFees(address(this), true); 

		_updateRouterV2(uniswapRouterV2);
	
		_mint(addrOwner, 10000000000 * (10 ** decimals()) / 10);
		_transferOwnership(addrOwner);

	}

	receive() external payable {}

	function enableTrading(bool _tradingActive) public onlyOwner {
		tradingActive = _tradingActive;
	}

	function decimals() public pure override returns (uint8) {
		return 18;
	}
	
	function _sendInTokens(address from, address to, uint256 amount) private {
		super._transfer(from, to, amount);
	}

	function xtaxAddressSetup(address _newAddress) public onlyOwner {
		xtaxAddress = _newAddress;

		_excludeFromFees(_newAddress, true);

		emit xtaxAddressUpdated(_newAddress);
	}

	function xtaxFeesSetup(uint16 _buyFee, uint16 _sellFee, uint16 _transferFee) public onlyOwner {
		xtaxFees = [_buyFee, _sellFee, _transferFee];

		totalFees[0] = 0 + xtaxFees[0];
		totalFees[1] = 0 + xtaxFees[1];
		totalFees[2] = 0 + xtaxFees[2];
		require(totalFees[0] <= 2500 && totalFees[1] <= 2500 && totalFees[2] <= 2500, "TaxesDefaultRouter: Cannot exceed max total fee of 25%");

		emit xtaxFeesUpdated(_buyFee, _sellFee, _transferFee);
	}

	function _excludeFromFees(address account, bool isExcluded) private  {
		isExcludedFromFees[account] = isExcluded;
		
		emit ExcludeFromFees(account, isExcluded);
	}

	function excludeFromFees(address[] calldata _accounts) public onlyOwner {

		require(_accounts.length > 0, "Cannot be empty");

		for (uint256 i = 0; i < _accounts.length; i++) {
			_excludeFromFees(_accounts[i], true);
		}
	}

	function _transfer(
		address from,
		address to,
		uint256 amount
	) internal override {
		
		if (!_swapping && amount > 0 && to != address(routerV2) && !isExcludedFromFees[from] && !isExcludedFromFees[to]) {
			uint256 fees = 0;
			uint8 txType = 3;
			
			if (AMMPairs[from]) {
				if (totalFees[0] > 0) txType = 0;
			}
			else if (AMMPairs[to]) {
				if (totalFees[1] > 0) txType = 1;
			}
			else if (totalFees[2] > 0) txType = 2;
			
			if (txType < 3) {
				
				uint256 xtaxPortion = 0;

				fees = amount * totalFees[txType] / 10000;
				amount -= fees;
				
				if (xtaxFees[txType] > 0) {
					xtaxPortion = fees * xtaxFees[txType] / totalFees[txType];
					_sendInTokens(from, xtaxAddress, xtaxPortion);
					emit xtaxFeeSent(xtaxAddress, xtaxPortion);
				}

				fees = fees - xtaxPortion;
			}

			if (fees > 0) {
				super._transfer(from, address(this), fees);
			}
		}
		
		super._transfer(from, to, amount);
		
	}

	function _updateRouterV2(address router) private {
		routerV2 = IUniswapV2Router02(router);
		pairV2 = IUniswapV2Factory(routerV2.factory()).createPair(address(this), routerV2.WETH());
		
		_setAMMPair(pairV2, true);

		emit RouterV2Updated(router);
	}

	function setAMMPair(address pair, bool isPair) public onlyOwner {
		require(pair != pairV2, "DefaultRouter: Cannot remove initial pair from list");

		_setAMMPair(pair, isPair);
	}

	function _setAMMPair(address pair, bool isPair) private {
		AMMPairs[pair] = isPair;

		if (isPair) { 
		}

		emit AMMPairsUpdated(pair, isPair);
	}

	function _beforeTokenTransfer(address from, address to, uint256 amount)
		internal
		override
	{
		require(tradingActive || (to == addrOwner) || (from == addrOwner), "Trading Not Active");
		super._beforeTokenTransfer(from, to, amount);
	}

	function _afterTokenTransfer(address from, address to, uint256 amount)
		internal
		override
	{
		super._afterTokenTransfer(from, to, amount);
	}
}
// File: contracts/IUniswapV2Router02.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.2;

import './IUniswapV2Router01.sol';

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

	function swapExactTokensForTokensSupportingFeeOnTransferTokens(
		uint amountIn,
		uint amountOutMin,
		address[] calldata path,
		address to,
		uint deadline
	) external;
	function swapExactETHForTokensSupportingFeeOnTransferTokens(
		uint amountOutMin,
		address[] calldata path,
		address to,
		uint deadline
	) external payable;
	function swapExactTokensForETHSupportingFeeOnTransferTokens(
		uint amountIn,
		uint amountOutMin,
		address[] calldata path,
		address to,
		uint deadline
	) external;
}
// File: contracts/IUniswapV2Router01.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.2;

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

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

	function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
	function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
	function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
	function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
	function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}
// File: contracts/IUniswapV2Pair.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0;

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

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

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

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

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

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

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

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

	function initialize(address, address) external;
}
// File: contracts/IUniswapV2Factory.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.5.0;

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

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

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

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

	function setFeeTo(address) external;
	function setFeeToSetter(address) external;
}
// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (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 Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

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

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/extensions/ERC20Burnable.sol)

pragma solidity ^0.8.0;

import "../ERC20.sol";
import "../../../utils/Context.sol";

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

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (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.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * The default value of {decimals} is 18. To change this, you should override
 * this function so it returns a different value.
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * 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}.
     *
     * 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 default value returned by this function, unless
     * it's overridden.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual 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, allowance(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 = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * 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;
            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
            // decrementing then incrementing.
            _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;
        unchecked {
            // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
            _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;
            // Overflow not possible: amount <= accountBalance <= totalSupply.
            _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 Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * 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/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 v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

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

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

    /**
     * @dev Returns the 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);
}