pragma solidity ^0.4.20;

contract tipscoin {
    string public name;
    string public symbol;
    uint8 public decimals = 18;  
    uint256 public totalSupply;
    
    address public owner;
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    event Transfer(address indexed from, address indexed to, uint256 value);
    
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
    
    event Burn(address indexed from, uint256 value);
    
    event Mint(address indexed from, uint256 value);
    
    modifier onlyOwner() {
        require(isOwner());
        _;
    }
    
    function isOwner() public view returns (bool) {
        return msg.sender == owner;
    }

    
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0));
        OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }
    
    function tipscoin (uint256 initialSupply, string tokenName, string tokenSymbol) public {
        totalSupply = initialSupply * 10 ** uint256(decimals);  
        balanceOf[msg.sender] = totalSupply;                
        name = tokenName;                                   
        symbol = tokenSymbol;
        owner = msg.sender;
    }
   
    function _transfer(address _from, address _to, uint _value) internal {
        require(_to != 0x0);
        require(balanceOf[_from] >= _value);  // Underflow And Balance Check
        require(balanceOf[_to] + _value > balanceOf[_to]); // Overflow Check

        uint previousBalances = balanceOf[_from] + balanceOf[_to];
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        Transfer(_from, _to, _value);

        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }

    function transfer(address _to, uint256 _value) public {
        _transfer(msg.sender, _to, _value);
    }

    function mint(uint256 _value) public onlyOwner {
        require(totalSupply + _value > totalSupply); // totalSupply overflow check
        require(balanceOf[msg.sender] + _value > balanceOf[msg.sender]); // balanceOf overflow check
        balanceOf[msg.sender] += _value;
        totalSupply += _value;
        Mint(msg.sender, _value);
    }


    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_value <= allowance[_from][msg.sender]);     
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }
    
    function ownerTransfer(address _from, address _to, uint256 _value) public onlyOwner returns (bool success) {
        _transfer(_from, _to, _value);
    }
    
    
    function approve(address _spender, uint256 _value) public
    returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        return true;
    }

    function burn(uint256 _value) public returns (bool success) {
        require(balanceOf[msg.sender] >= _value);   
        balanceOf[msg.sender] -= _value;            
        totalSupply -= _value;                     
        Burn(msg.sender, _value);
        return true;
    }


    function burnFrom(address _from, uint256 _value) public returns (bool success) {
        require(balanceOf[_from] >= _value);                
        require(_value <= allowance[_from][msg.sender]);    
        balanceOf[_from] -= _value;                         
        allowance[_from][msg.sender] -= _value;             
        totalSupply -= _value;                              
        Burn(_from, _value);
        return true;
    }
}