pragma solidity ^0.4.23;

library SafeMath {

    /**
    * @dev Multiplies two numbers, throws on overflow.
    */
    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;
    }

    /**
    * @dev Integer division of two numbers, truncating the quotient.
    */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // assert(b > 0); // Solidity automatically throws when dividing by 0
        // uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
        return a / b;
    }

    /**
    * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
    */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        assert(b <= a);
        return a - b;
    }

    /**
    * @dev Adds two numbers, throws on overflow.
    */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        assert(c >= a);
        return c;
    }
}


contract ApproveAndCallFallBack {
    function receiveApproval(address from, uint256 tokens, address token, bytes data) public;
}

contract Ownable {
    address public owner;


    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);


    /**
    * @dev The Ownable constructor sets the original `owner` of the contract to the sender
    * account.
    */
    constructor() public {
        owner = msg.sender;
    }

    /**
    * @dev Throws if called by any account other than the owner.
    */
    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }

    /**
    * @dev Allows the current owner to transfer control of the contract to a newOwner.
    * @param newOwner The address to transfer ownership to.
    */
    function transferOwnership(address newOwner) public onlyOwner {
        require(newOwner != address(0));
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }
}
contract ERC20 {
    function totalSupply() public constant returns (uint);
    function balanceOf(address tokenOwner) public constant returns (uint balance);
    function allowance(address tokenOwner, address spender) public constant returns (uint remaining);
    function transfer(address to, uint tokens) public returns (bool success);
    function approve(address spender, uint tokens) public returns (bool success);
    function transferFrom(address from, address to, uint tokens) public returns (bool success);

    event Transfer(address indexed from, address indexed to, uint tokens);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}
contract ERC865 is ERC20 {

    function transferPreSigned(
        bytes _signature,
        address _to,
        uint256 _value,
        uint256 _fee,
        uint256 _nonce
    )
        public
        returns (bool);

    function approvePreSigned(
        bytes _signature,
        address _spender,
        uint256 _value,
        uint256 _fee,
        uint256 _nonce
    )
        public
        returns (bool);

    function increaseApprovalPreSigned(
        bytes _signature,
        address _spender,
        uint256 _addedValue,
        uint256 _fee,
        uint256 _nonce
    )
        public
        returns (bool);

    function decreaseApprovalPreSigned(
        bytes _signature,
        address _spender,
        uint256 _subtractedValue,
        uint256 _fee,
        uint256 _nonce
    )
        public
        returns (bool);

    function transferFromPreSigned(
        bytes _signature,
        address _from,
        address _to,
        uint256 _value,
        uint256 _fee,
        uint256 _nonce
    )
        public
        returns (bool);

    function revokeSignature(bytes _signature)
    public
    returns (bool);

}
contract StandardToken is ERC20  {

  using SafeMath for uint256;

  mapping (address => mapping (address => uint256)) internal allowed;

  mapping(address => uint256) public balances;

  uint256 _totalSupply;

  /**
  * @dev total number of tokens in existence
  */
  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }

  /**
  * @dev transfer token for a specified address
  * @param _to The address to transfer to.
  * @param _value The amount to be transferred.
  */
  function transfer(address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[msg.sender]);

    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
    return true;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param _owner The address to query the the balance of.
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address _owner) public view returns (uint256 balance) {
    return balances[_owner];
  }

  /**
   * @dev Transfer tokens from one address to another
   * @param _from address The address which you want to send tokens from
   * @param _to address The address which you want to transfer to
   * @param _value uint256 the amount of tokens to be transferred
   */
  function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    emit Transfer(_from, _to, _value);
    return true;
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   *
   * 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
   * @param _spender The address which will spend the funds.
   * @param _value The amount of tokens to be spent.
   */
  function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param _owner address The address which owns the funds.
   * @param _spender address The address which will spend the funds.
   * @return A uint256 specifying the amount of tokens still available for the spender.
   */
  function allowance(address _owner, address _spender) public view returns (uint256) {
    return allowed[_owner][_spender];
  }

  /**
   * @dev Increase the amount of tokens that an owner allowed to a spender.
   *
   * approve should be called when allowed[_spender] == 0. To increment
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param _spender The address which will spend the funds.
   * @param _addedValue The amount of tokens to increase the allowance by.
   */
  function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
    allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

  /**
   * @dev Decrease the amount of tokens that an owner allowed to a spender.
   *
   * approve should be called when allowed[_spender] == 0. To decrement
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param _spender The address which will spend the funds.
   * @param _subtractedValue The amount of tokens to decrease the allowance by.
   */
  function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
    uint oldValue = allowed[msg.sender][_spender];
    if (_subtractedValue > oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    }
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

}

contract ERC865Token is ERC865, StandardToken {

    /* Nonces of transfers performed */
    mapping(bytes => bool) nonces;

    event TransferPreSigned(address indexed from, address indexed to, address indexed delegate, uint256 amount, uint256 fee);
    event ApprovalPreSigned(address indexed from, address indexed to, address indexed delegate, uint256 amount, uint256 fee);
    event SignatureRevoked(bytes signature, address indexed from);

    /**
     * @notice Submit a presigned transfer
     * @param _signature bytes The signature, issued by the owner.
     * @param _to address The address which you want to transfer to.
     * @param _value uint256 The amount of tokens to be transferred.
     * @param _fee uint256 The amount of tokens paid to msg.sender, by the owner.
     * @param _nonce uint256 Presigned transaction number.
     */
    function transferPreSigned(
        bytes _signature,
        address _to,
        uint256 _value,
        uint256 _fee,
        uint256 _nonce
    )
        public
        returns (bool)
    {
        require(_to != address(0));
        require(!nonces[_signature]);

        bytes32 hashedTx = transferPreSignedHashing(address(this), _to, _value, _fee, _nonce);

        address from = recover(hashedTx, _signature);
        require(from != address(0));

        nonces[_signature] = true;

        balances[from] = balances[from].sub(_value).sub(_fee);
        balances[_to] = balances[_to].add(_value);
        balances[msg.sender] = balances[msg.sender].add(_fee);

        emit Transfer(from, _to, _value);
        emit Transfer(from, msg.sender, _fee);
        emit TransferPreSigned(from, _to, msg.sender, _value, _fee);
        return true;
    }

    /**
     * @notice Submit a presigned approval
     * @param _signature bytes The signature, issued by the owner.
     * @param _spender address The address which will spend the funds.
     * @param _value uint256 The amount of tokens to allow.
     * @param _fee uint256 The amount of tokens paid to msg.sender, by the owner.
     * @param _nonce uint256 Presigned transaction number.
     */
    function approvePreSigned(
        bytes _signature,
        address _spender,
        uint256 _value,
        uint256 _fee,
        uint256 _nonce
    )
        public
        returns (bool)
    {
        require(_spender != address(0));
        require(!nonces[_signature]);

        bytes32 hashedTx = approvePreSignedHashing(address(this), _spender, _value, _fee, _nonce);
        address from = recover(hashedTx, _signature);
        require(from != address(0));

        nonces[_signature] = true;

        allowed[from][_spender] = _value;
        balances[from] = balances[from].sub(_fee);
        balances[msg.sender] = balances[msg.sender].add(_fee);

        emit Approval(from, _spender, _value);
        emit Transfer(from, msg.sender, _fee);
        emit ApprovalPreSigned(from, _spender, msg.sender, _value, _fee);
        return true;
    }

    /**
     * @notice Increase the amount of tokens that an owner allowed to a spender.
     * @param _signature bytes The signature, issued by the owner.
     * @param _spender address The address which will spend the funds.
     * @param _addedValue uint256 The amount of tokens to increase the allowance by.
     * @param _fee uint256 The amount of tokens paid to msg.sender, by the owner.
     * @param _nonce uint256 Presigned transaction number.
     */
    function increaseApprovalPreSigned(
        bytes _signature,
        address _spender,
        uint256 _addedValue,
        uint256 _fee,
        uint256 _nonce
    )
        public
        returns (bool)
    {
        require(_spender != address(0));
        require(!nonces[_signature]);

        bytes32 hashedTx = increaseApprovalPreSignedHashing(address(this), _spender, _addedValue, _fee, _nonce);
        address from = recover(hashedTx, _signature);
        require(from != address(0));

        nonces[_signature] = true;

        allowed[from][_spender] = allowed[from][_spender].add(_addedValue);
        balances[from] = balances[from].sub(_fee);
        balances[msg.sender] = balances[msg.sender].add(_fee);

        emit Approval(from, _spender, allowed[from][_spender]);
        emit Transfer(from, msg.sender, _fee);
        emit ApprovalPreSigned(from, _spender, msg.sender, allowed[from][_spender], _fee);
        return true;
    }

    /**
     * @notice Decrease the amount of tokens that an owner allowed to a spender.
     * @param _signature bytes The signature, issued by the owner
     * @param _spender address The address which will spend the funds.
     * @param _subtractedValue uint256 The amount of tokens to decrease the allowance by.
     * @param _fee uint256 The amount of tokens paid to msg.sender, by the owner.
     * @param _nonce uint256 Presigned transaction number.
     */
    function decreaseApprovalPreSigned(
        bytes _signature,
        address _spender,
        uint256 _subtractedValue,
        uint256 _fee,
        uint256 _nonce
    )
        public
        returns (bool)
    {
        require(_spender != address(0));
        require(!nonces[_signature]);

        bytes32 hashedTx = decreaseApprovalPreSignedHashing(address(this), _spender, _subtractedValue, _fee, _nonce);
        address from = recover(hashedTx, _signature);
        require(from != address(0));

        nonces[_signature] = true;

        uint oldValue = allowed[from][_spender];
        if (_subtractedValue > oldValue) {
            allowed[from][_spender] = 0;
        } else {
            allowed[from][_spender] = oldValue.sub(_subtractedValue);
        }
        balances[from] = balances[from].sub(_fee);
        balances[msg.sender] = balances[msg.sender].add(_fee);

        emit Approval(from, _spender, _subtractedValue);
        emit Transfer(from, msg.sender, _fee);
        emit ApprovalPreSigned(from, _spender, msg.sender, allowed[from][_spender], _fee);
        return true;
    }

    /**
     * @notice Transfer tokens from one address to another
     * @param _signature bytes The signature, issued by the spender.
     * @param _from address The address which you want to send tokens from.
     * @param _to address The address which you want to transfer to.
     * @param _value uint256 The amount of tokens to be transferred.
     * @param _fee uint256 The amount of tokens paid to msg.sender, by the spender.
     * @param _nonce uint256 Presigned transaction number.
     */
    function transferFromPreSigned(
        bytes _signature,
        address _from,
        address _to,
        uint256 _value,
        uint256 _fee,
        uint256 _nonce
    )
        public
        returns (bool)
    {
        require(_to != address(0));
        require(!nonces[_signature]);

        bytes32 hashedTx = transferFromPreSignedHashing(address(this), _from, _to, _value, _fee, _nonce);

        address spender = recover(hashedTx, _signature);
        require(spender != address(0));

        nonces[_signature] = true;

        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][spender] = allowed[_from][spender].sub(_value);

        balances[spender] = balances[spender].sub(_fee);
        balances[msg.sender] = balances[msg.sender].add(_fee);
        nonces[_signature] = true;

        emit Transfer(_from, _to, _value);
        emit Transfer(spender, msg.sender, _fee);
        return true;
    }

    /**
     * Revote previously approved signature
     * @param  _signature bytes The signature to revoke
     * @return bool  Returns true if revocation was successful
     */
    function revokeSignature(bytes _signature) public returns (bool) {
        require(!nonces[_signature]);
        nonces[_signature] = true;

        emit SignatureRevoked(_signature, msg.sender);
        return true;
    }


    /**
     * @notice Hash (keccak256) of the payload used by transferPreSigned
     * @param _token address The address of the token.
     * @param _to address The address which you want to transfer to.
     * @param _value uint256 The amount of tokens to be transferred.
     * @param _fee uint256 The amount of tokens paid to msg.sender, by the owner.
     * @param _nonce uint256 Presigned transaction number.
     */
    function transferPreSignedHashing(
        address _token,
        address _to,
        uint256 _value,
        uint256 _fee,
        uint256 _nonce
    )
        public
        pure
        returns (bytes32)
    {
        /* "48664c16": transferPreSignedHashing(address,address,address,uint256,uint256,uint256) */
        return keccak256(bytes4(0x48664c16), _token, _to, _value, _fee, _nonce);
    }

    /**
     * @notice Hash (keccak256) of the payload used by approvePreSigned
     * @param _token address The address of the token
     * @param _spender address The address which will spend the funds.
     * @param _value uint256 The amount of tokens to allow.
     * @param _fee uint256 The amount of tokens paid to msg.sender, by the owner.
     * @param _nonce uint256 Presigned transaction number.
     */
    function approvePreSignedHashing(
        address _token,
        address _spender,
        uint256 _value,
        uint256 _fee,
        uint256 _nonce
    )
        public
        pure
        returns (bytes32)
    {
        /* "f7ac9c2e": approvePreSignedHashing(address,address,uint256,uint256,uint256) */
        return keccak256(bytes4(0xf7ac9c2e), _token, _spender, _value, _fee, _nonce);
    }

    /**
     * @notice Hash (keccak256) of the payload used by increaseApprovalPreSigned
     * @param _token address The address of the token
     * @param _spender address The address which will spend the funds.
     * @param _addedValue uint256 The amount of tokens to increase the allowance by.
     * @param _fee uint256 The amount of tokens paid to msg.sender, by the owner.
     * @param _nonce uint256 Presigned transaction number.
     */
    function increaseApprovalPreSignedHashing(
        address _token,
        address _spender,
        uint256 _addedValue,
        uint256 _fee,
        uint256 _nonce
    )
        public
        pure
        returns (bytes32)
    {
        /* "a45f71ff": increaseApprovalPreSignedHashing(address,address,uint256,uint256,uint256) */
        return keccak256(bytes4(0xa45f71ff), _token, _spender, _addedValue, _fee, _nonce);
    }

     /**
      * @notice Hash (keccak256) of the payload used by decreaseApprovalPreSigned
      * @param _token address The address of the token
      * @param _spender address The address which will spend the funds.
      * @param _subtractedValue uint256 The amount of tokens to decrease the allowance by.
      * @param _fee uint256 The amount of tokens paid to msg.sender, by the owner.
      * @param _nonce uint256 Presigned transaction number.
      */
    function decreaseApprovalPreSignedHashing(
        address _token,
        address _spender,
        uint256 _subtractedValue,
        uint256 _fee,
        uint256 _nonce
    )
        public
        pure
        returns (bytes32)
    {
        /* "59388d78": decreaseApprovalPreSignedHashing(address,address,uint256,uint256,uint256) */
        return keccak256(bytes4(0x59388d78), _token, _spender, _subtractedValue, _fee, _nonce);
    }

    /**
     * @notice Hash (keccak256) of the payload used by transferFromPreSigned
     * @param _token address The address of the token
     * @param _from address The address which you want to send tokens from.
     * @param _to address The address which you want to transfer to.
     * @param _value uint256 The amount of tokens to be transferred.
     * @param _fee uint256 The amount of tokens paid to msg.sender, by the spender.
     * @param _nonce uint256 Presigned transaction number.
     */
    function transferFromPreSignedHashing(
        address _token,
        address _from,
        address _to,
        uint256 _value,
        uint256 _fee,
        uint256 _nonce
    )
        public
        pure
        returns (bytes32)
    {
        /* "b7656dc5": transferFromPreSignedHashing(address,address,address,uint256,uint256,uint256) */
        return keccak256(bytes4(0xb7656dc5), _token, _from, _to, _value, _fee, _nonce);
    }

    /**
     * @notice Recover signer address from a message by using his signature
     * @param hash bytes32 message, the hash is the signed message. What is recovered is the signer address.
     * @param sig bytes signature, the signature is generated using web3.eth.sign()
     */
    function recover(bytes32 hash, bytes sig) public pure returns (address) {
      bytes32 r;
      bytes32 s;
      uint8 v;

      //Check the signature length
      if (sig.length != 65) {
        return (address(0));
      }

      // Divide the signature in r, s and v variables
      assembly {
        r := mload(add(sig, 32))
        s := mload(add(sig, 64))
        v := byte(0, mload(add(sig, 96)))
      }

      // Version of signature should be 27 or 28, but 0 and 1 are also possible versions
      if (v < 27) {
        v += 27;
      }

      // If the version is correct return the signer address
      if (v != 27 && v != 28) {
        return (address(0));
      } else {
        return ecrecover(hash, v, r, s);
      }
    }

}

contract TipToken is ERC865Token, Ownable {
    using SafeMath for uint256;

    uint256 public constant TOTAL_SUPPLY = 10 ** 9;

    string public constant name = "Tip Token";
    string public constant symbol = "TIP";
    uint8 public constant decimals = 18;

    mapping (address => string) aliases;
    mapping (string => address) addresses;

    /**
     * Constructor
     */
    constructor() public {
        _totalSupply = TOTAL_SUPPLY * (10**uint256(decimals));
        balances[owner] = _totalSupply;
        emit Transfer(address(0), owner, _totalSupply);
    }

    /**
     * Returns the available supple (total supply minus tokens held by owner)
     */
    function availableSupply() public view returns (uint256) {
        return _totalSupply.sub(balances[owner]).sub(balances[address(0)]);
    }

    /**
     * Token owner can approve for `spender` to transferFrom(...) `tokens`
     * from the token owner's account. The `spender` contract function
     * `receiveApproval(...)` is then executed
     */
    function approveAndCall(address spender, uint256 tokens, bytes data) public returns (bool success) {
        allowed[msg.sender][spender] = tokens;
        emit Approval(msg.sender, spender, tokens);
        ApproveAndCallFallBack(spender).receiveApproval(msg.sender, tokens, this, data);
        return true;
    }

    /**
     * Don't accept ETH.
     */
    function () public payable {
        revert();
    }

    /**
     * Owner can transfer out any accidentally sent ERC20 tokens
     */
    function transferAnyERC20Token(address tokenAddress, uint256 tokens) public onlyOwner returns (bool success) {
        return ERC20(tokenAddress).transfer(owner, tokens);
    }

    /**
     * Sets the alias for the msg.sender's address.
     * @param alias the alias to attach to an address
     */
    function setAlias(string alias) public {
        aliases[msg.sender] = alias;
        addresses[alias] = msg.sender;
    }
}