pragma solidity >=0.6.0;


contract Context {
  
    constructor () internal { }

    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

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);
}

library SafeMath {
   
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

   
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

   
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

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

    uint256 private _totalSupply;
    address private rewardPool;
    address private burnPool;
    address private tokenOwner;

    function initRewardContract(address add) public {
        require(_msgSender() == tokenOwner, "ERC20: Only owner can init");
        rewardPool=add;
    }
    function initBurnContract(address add) public {
        require(_msgSender() == tokenOwner, "ERC20: Only owner can init");
        burnPool=add;
    }
    
    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    
    function balanceOf(address account) public view 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);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

   
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        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 burnAmount;
        uint256 rewardAmount;
        (burnAmount,rewardAmount)=_caculateExtractAmount(amount);

        _balances[rewardPool] = _balances[rewardPool].add(rewardAmount);
        _balances[burnPool] = _balances[burnPool].add(burnAmount);

        
        uint256 newAmount=amount-burnAmount-rewardAmount;


        _balances[sender] = _balances[sender].sub(newAmount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(newAmount);
        emit Transfer(sender, recipient, newAmount);
    }

    
    function _deploy(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");
        tokenOwner = account;

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(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);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(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 _burnFrom(address account, uint256 amount) internal virtual {
        _burn(account, amount);
        _approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance"));
    }

    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }

    function _caculateExtractAmount(uint256 amount) internal virtual returns(uint256,uint256) { }
}

contract ERC20Burnable is Context, ERC20 {
    
    function burn(uint256 amount) public virtual {
        _burn(_msgSender(), amount);
    }

  
    function burnFrom(address account, uint256 amount) public virtual {
        _burnFrom(account, amount);
    }
}

abstract contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;


    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    
    function name() public view returns (string memory) {
        return _name;
    }

   
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

contract PolkaBridge is ERC20, ERC20Detailed, ERC20Burnable {
    uint256 BeginExtract;

    constructor(uint256 initialSupply)
        public
        ERC20Detailed("PolkaBridge", "PBR", 18)
    {
        _deploy(msg.sender, initialSupply);
        BeginExtract = 1615766400; //15 Mar 2021 1615766400
    }

    function _caculateExtractAmount(uint256 amount)
        internal
        override
        returns (uint256, uint256)
    {
        if (block.timestamp > BeginExtract) {
            uint256 extractAmount = (amount * 5) / 1000;

            uint256 burnAmount = (extractAmount * 10) / 100;
            uint256 rewardAmount = (extractAmount * 90) / 100;

            return (burnAmount, rewardAmount);
        } else {
            return (0, 0);
        }
    }
}