pragma solidity >=0.5.10;
 
interface IERC20 {
  function totalSupply() external view returns (uint256);
  function balanceOf(address who) external view returns (uint256);
  function allowance(address owner, address spender) external view returns (uint256);
  function transfer(address to, uint256 value) external returns (bool);
  function approve(address spender, uint256 value) external returns (bool);
  function transferFrom(address from, address to, uint256 value) 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 mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    assert(c / a == b);
    return c;
  }
 
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a / b;
    return c;
  }
 
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }
 
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
 
  function ceil(uint256 a, uint256 m) internal pure returns (uint256) {
    uint256 c = add(a,m);
    uint256 d = sub(c,1);
    return mul(div(d,m),m);
  }
}

contract Owned {
  address public owner;
  address public newOwner;

  event OwnershipTransferred(address indexed _from, address indexed _to);

  constructor() public {
    owner = msg.sender;
  }

  modifier onlyOwner {
    require(msg.sender == owner);
    _;
  }

  function transferOwnership(address _newOwner) public onlyOwner {
    newOwner = _newOwner;
  }
  function acceptOwnership() public {
    require(msg.sender == newOwner);
    emit OwnershipTransferred(owner, newOwner);
    owner = newOwner;
    newOwner = address(0);
  }
}

contract ERC20Detailed is IERC20, Owned {
 
  uint8 private _Tokendecimals;
  string private _Tokenname;
  string private _Tokensymbol;
 
  constructor(string memory name, string memory symbol, uint8 decimals) public {
   
   _Tokendecimals = decimals;
    _Tokenname = name;
    _Tokensymbol = symbol;
   
  }
 
  function name() public view returns(string memory) {
    return _Tokenname;
  }
 
  function symbol() public view returns(string memory) {
    return _Tokensymbol;
  }
 
  function decimals() public view returns(uint8) {
    return _Tokendecimals;
  }
}

contract DoYourTip is ERC20Detailed {
 
  using SafeMath for uint256;
  mapping (address => uint256) private _DoYourTipTokenBalances;
  mapping (address => mapping (address => uint256)) private _allowed;
  string constant tokenName = "DoYourTip";
  string constant tokenSymbol = "DYT";
  uint8  constant tokenDecimals = 18;
  uint256 _totalSupply = 2000000000000000000000000;
  
  mapping (address => bool) private _DoYourTipTokenWhitelistAddrs;
  bool _burningFlag = true;
 
  constructor() public payable ERC20Detailed(tokenName, tokenSymbol, tokenDecimals) {
    _mint(msg.sender, _totalSupply);
  }
 
  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }
 
  function balanceOf(address owner) public view returns (uint256) {
    return _DoYourTipTokenBalances[owner];
  }
 
  function allowance(address owner, address spender) public view returns (uint256) {
    return _allowed[owner][spender];
  }
 
  function transfer(address to, uint256 value) public returns (bool) {
    require(value <= _DoYourTipTokenBalances[msg.sender]);
    require(to != address(0));
    
    uint256 DoYourTipTokenDecay = 0;
    uint256 tokensToTransfer = value;
    
    bool burnSomeDYT = ((_burningFlag) && (_DoYourTipTokenWhitelistAddrs[to] != true) && (_DoYourTipTokenWhitelistAddrs[msg.sender] != true));
    
    if(burnSomeDYT) {
        DoYourTipTokenDecay = value.div(50);
        tokensToTransfer = value.sub(DoYourTipTokenDecay);
    }
    _DoYourTipTokenBalances[msg.sender] = _DoYourTipTokenBalances[msg.sender].sub(value);
    _DoYourTipTokenBalances[to] = _DoYourTipTokenBalances[to].add(tokensToTransfer);
    
    if(burnSomeDYT) {
        _totalSupply = _totalSupply.sub(DoYourTipTokenDecay);
        emit Transfer(msg.sender, address(0), DoYourTipTokenDecay);
    }
    emit Transfer(msg.sender, to, tokensToTransfer);
    return true;
  }
 
  function multiTransfer(address[] memory receivers, uint256[] memory amounts) public {
    for (uint256 i = 0; i < receivers.length; i++) {
      transfer(receivers[i], amounts[i]);
    }
  }
 
  function approve(address spender, uint256 value) public returns (bool) {
    require(spender != address(0));
    _allowed[msg.sender][spender] = value;
    emit Approval(msg.sender, spender, value);
    return true;
  }
 
  function transferFrom(address from, address to, uint256 value) public returns (bool) {
    require(value <= _DoYourTipTokenBalances[from]);
    require(value <= _allowed[from][msg.sender]);
    require(to != address(0));
 
    _DoYourTipTokenBalances[from] = _DoYourTipTokenBalances[from].sub(value);
    
    uint256 DoYourTipTokenDecay = 0;
    uint256 tokensToTransfer = value;
    bool burnSomeDYT = ((_burningFlag) && (_DoYourTipTokenWhitelistAddrs[to] != true) && (_DoYourTipTokenWhitelistAddrs[msg.sender] != true));
    
    if(burnSomeDYT) {
        DoYourTipTokenDecay = value.div(50);
        tokensToTransfer = value.sub(DoYourTipTokenDecay);
    }
 
    _DoYourTipTokenBalances[to] = _DoYourTipTokenBalances[to].add(tokensToTransfer);
    _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
 
    emit Transfer(from, to, tokensToTransfer);
    
    if(burnSomeDYT) {
        _totalSupply = _totalSupply.sub(DoYourTipTokenDecay);
        emit Transfer(from, address(0), DoYourTipTokenDecay);
    }
    return true;
  }
 
  function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
    require(spender != address(0));
    _allowed[msg.sender][spender] = (_allowed[msg.sender][spender].add(addedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }
 
  function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
    require(spender != address(0));
    _allowed[msg.sender][spender] = (_allowed[msg.sender][spender].sub(subtractedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }
 
  function _mint(address account, uint256 amount) internal {
    require(amount != 0);
    _DoYourTipTokenBalances[account] = _DoYourTipTokenBalances[account].add(amount);
    emit Transfer(address(0), account, amount);
  }
 
  function burn(uint256 amount) external {
    _burn(msg.sender, amount);
  }
 
  function _burn(address account, uint256 amount) internal {
    require(amount != 0);
    require(amount <= _DoYourTipTokenBalances[account]);
    _totalSupply = _totalSupply.sub(amount);
    _DoYourTipTokenBalances[account] = _DoYourTipTokenBalances[account].sub(amount);
    emit Transfer(account, address(0), amount);
  }
 
  function burnFrom(address account, uint256 amount) external {
    require(amount <= _allowed[account][msg.sender]);
    _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(amount);
    _burn(account, amount);
  }
  
  //OWNER ONLY FUNCTIONS

  function addWhitelist(address user) public onlyOwner() {
    require(_DoYourTipTokenWhitelistAddrs[user] != true);
    _DoYourTipTokenWhitelistAddrs[user] = true;
  }
  
  function removeWhitelist(address user) public onlyOwner() {
    require(_DoYourTipTokenWhitelistAddrs[user] == true);
    delete _DoYourTipTokenWhitelistAddrs[user];
  }

  function turnBurningOn() public onlyOwner() {
    _burningFlag = true;
  }

  function turnBurningOff() public onlyOwner() {
    _burningFlag = false;
  }

}