contract DFX is SafeMath{

    string public name = "DeFiProtocol";
    string public symbol = "DFX";
    uint8 public decimals = 18;
    uint256 public totalSupply;
    uint256 public INITIAL_SUPPLY = 10000000000000000000000000000;
  	address public owner;

    /* This creates an array with all balances */
    mapping (address => uint256) public balanceOf;
  	mapping (address => uint256) public freezeOf;
    mapping (address => mapping (address => uint256)) public allowance;

    /* This generates a public event on the blockchain that will notify clients */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /* This notifies clients about the amount burnt */
    event Burn(address indexed from, uint256 value);

	/* This notifies clients about the amount frozen */
    event Freeze(address indexed from, uint256 value);

	/* This notifies clients about the amount unfrozen */
    event Unfreeze(address indexed from, uint256 value);

    /* Initializes contract with initial supply tokens to the creator of the contract */
    constructor () public {
        balanceOf[msg.sender] = INITIAL_SUPPLY;              // Give the creator all initial tokens
        totalSupply = INITIAL_SUPPLY;                        // Update total supply
		    owner = msg.sender;
    }

    /* Send coins */
    function transfer(address _to, uint256 _value) public {
        require (_to != address(0),"0 address not allowed");           // Prevent transfer to 0x0 address. Use burn() instead
	    	require (_value > 0, "value invalid ");
        require (balanceOf[msg.sender] >= _value, "balance not enough") ;           // Check if the sender has enough
        require (balanceOf[_to] + _value > balanceOf[_to],"overflow") ; // Check for overflows
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);                     // Subtract from the sender
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);                            // Add the same to the recipient
        emit Transfer(msg.sender, _to, _value);                   // Notify anyone listening that this transfer took place
    }

    /* Allow another contract to spend some tokens in your behalf */
    function approve(address _spender, uint256 _value) public
        returns (bool success) {
	    	require (_value > 0, "value invalid") ;
        allowance[msg.sender][_spender] = _value;
        return true;
    }


    /* A contract attempts to get the coins */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
		require (_to != address(0),"0 address not allowed");   // Prevent transfer to 0x0 address. Use burn() instead
		require (_value > 0, "value invalid ");
        require (balanceOf[msg.sender] >= _value, "balance not enough") ;  // Check if the sender has enough
        require (balanceOf[_to] + _value > balanceOf[_to],"overflow") ; // Check for overflows
        require (_value <= allowance[_from][msg.sender],"allowance not enough") ;     // Check allowance
        balanceOf[_from] = SafeMath.safeSub(balanceOf[_from], _value);                           // Subtract from the sender
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);                             // Add the same to the recipient
        allowance[_from][msg.sender] = SafeMath.safeSub(allowance[_from][msg.sender], _value);
        emit Transfer(_from, _to, _value);
        return true;
    }

    function burn(uint256 _value) public returns (bool success)  {
        require (balanceOf[msg.sender] >= _value, "balance not enough") ;            // Check if the sender has enough
	    	require (_value > 0, "value invalid ");
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);                      // Subtract from the sender
        totalSupply = SafeMath.safeSub(totalSupply,_value);                                // Updates totalSupply
        emit Burn(msg.sender, _value);
        return true;
    }

  	function freeze(uint256 _value) public returns (bool success) {
        require (balanceOf[msg.sender] >= _value, "balance not enough") ;       // Check if the sender has enough
        require (_value > 0, "value invalid ");
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);                      // Subtract from the sender
        freezeOf[msg.sender] = SafeMath.safeAdd(freezeOf[msg.sender], _value);                                // Updates totalSupply
        emit Freeze(msg.sender, _value);
        return true;
    }

  	function unfreeze(uint256 _value) public returns (bool success) {
        require (balanceOf[msg.sender] >= _value, "balance not enough") ;     // Check if the sender has enough
	    	 require (_value > 0, "value invalid ");
        freezeOf[msg.sender] = SafeMath.safeSub(freezeOf[msg.sender], _value);                      // Subtract from the sender
		    balanceOf[msg.sender] = SafeMath.safeAdd(balanceOf[msg.sender], _value);
        emit Unfreeze(msg.sender, _value);
        return true;
    }

	// transfer balance to owner
	function withdrawEther(uint256 amount) public {
		require(msg.sender == owner,"only owner");
		owner.transfer(amount);
	}

	// can accept ether
	function() payable public{
    }
}
function approve(address _spender, uint256 _value) public
    returns (bool success) {
 	require (_value > 0, "value invalid") ;
    allowance[msg.sender][_spender] = _value;
    return true;
}

/* Allow another contract to spend some tokens in your behalf */