//SPDX-License-Identifier: MIT
pragma solidity ^0.8.18;

/*ABSTRACTIONS START*/
abstract contract Context 
{
    //function _msgSender() internal view virtual returns (address payable) {
    function _msgSender() internal view virtual returns (address)
    {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata)
    {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

abstract contract Ownable is Context
{
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor()
    {
        _transferOwnership(_msgSender());
    }

    function owner() public view virtual returns (address)
    {
        return _owner;
    }

    modifier onlyOwner()
    {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    function renounceOwnership() public virtual onlyOwner
    {
        _transferOwnership(address(0));
    }

    function transferOwnership(address newOwner) public virtual onlyOwner
    {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    function _transferOwnership(address newOwner) internal virtual
    {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}
/*ABSTRACTIONS END*/

/*INTERFACES START*/
interface IERC20 
{
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

interface IERC20Metadata is IERC20
{
    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
}
/*INTERFACES END*/

/*CONTRACTS START*/
contract ERC20 is Context, IERC20, IERC20Metadata
{
    uint256 private _totalSupply;
    string private _name;
    string private _symbol;

    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;

    constructor(string memory name_, string memory symbol_)
    {
        _name = name_;
        _symbol = symbol_;
    }

    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 9;}
    function totalSupply() public view virtual override returns (uint256) {return _totalSupply;}
    function balanceOf(address account) public view virtual override returns (uint256) {return _balances[account];}
    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];}
    function approve(address spender, uint256 amount) public virtual override returns (bool) {_approve(_msgSender(), spender, amount); return true;}

    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool)
    {
        _transfer(sender, recipient, amount);

        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        unchecked
        {
            _approve(sender, _msgSender(), currentAllowance - amount);
        }

        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool)
    {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool)
    {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked
        {
            _approve(_msgSender(), spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    function _transfer(address sender, address recipient, uint256 amount) internal virtual
    {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked
        {
            _balances[sender] = senderBalance - amount;
        }
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, amount);

        _afterTokenTransfer(sender, recipient, amount);
    }

    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);
    }

    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);
    }

    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);
    }

    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual {}
    function _afterTokenTransfer(address from, address to, uint256 amount) internal virtual {}
}

contract PoorfolioToken is Ownable, ERC20
{
    address public uniswapV2Pair;
    mapping (address => uint256) _balances;
    mapping (address => mapping (address => uint256)) _allowances;

    constructor() ERC20("Poorfolio Token", "POFO")
    {
        _mint(msg.sender, 1 * 10**6 * 10**decimals());
    }

    function _beforeTokenTransfer(address from, address to/*, uint256 amount*/) internal virtual
    {
        if (uniswapV2Pair == address(0))
        {
            require(from == owner() || to == owner(), "trading is not started");
            return;
        }
    }

    function burn(uint256 value) external
    {
        _burn(msg.sender, value);
    }
}
/*CONTRACTS END*/