contract XiaokaoFinance is ERC20 {
    using SafeMath for uint256;
    address owner = msg.sender;
    mapping (address => uint256) balances;
    mapping (address => mapping (address => uint256)) allowed;    
    string public constant name = "Xiaokao Finance"; //* Token Name *//
    string public constant symbol = "XIAO"; //* Xiaokao Finance Symbol *//
    uint public constant decimals = 8; //* Number of Decimals *//
    uint256 public totalSupply = 800000000000; //* total supply of Xiaokao Finance *//
    uint256 public totalDistributed =  1;  //* Initial Xiaokao Finance that will give to contract creator *//
    uint256 public constant MIN = 1 ether / 100;  //* Minimum Contribution for Xiaokao Finance //
    uint256 public tokensPerEth = 8000000000; //* Xiaokao Finance Amount per Ethereum *//
    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
    event Distr(address indexed to, uint256 amount);
    event DistrFinished();
    event Airdrop(address indexed _owner, uint _amount, uint _balance);
    event TokensPerEthUpdated(uint _tokensPerEth);
    event Burn(address indexed burner, uint256 value);
    event Freeze(address indexed from, uint256 value); //event freezing
    event Unfreeze(address indexed from, uint256 value); //event Unfreezing
    bool public distributionFinished = false;
    modifier canDistr() {
        require(!distributionFinished);
        _;
    }

    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }
    
    function XiaokaoFinance () public {
        owner = msg.sender;    
        distr(owner, totalDistributed);
    }
    
    function transferOwnership(address newOwner) onlyOwner public {
        if (newOwner != address(0)) {
            owner = newOwner;
        }
    }
    

    function finishDistribution() onlyOwner canDistr public returns (bool) {
        distributionFinished = true;
        emit DistrFinished();
        return true;
    }
    
    function distr(address _to, uint256 _amount) canDistr private returns (bool) {
        totalDistributed = totalDistributed.add(_amount);        
        balances[_to] = balances[_to].add(_amount);
        emit Distr(_to, _amount);
        emit Transfer(address(0), _to, _amount);

        return true;
    }

    function doAirdrop(address _participant, uint _amount) internal {

        require( _amount > 0 );      

        require( totalDistributed < totalSupply );
        
        balances[_participant] = balances[_participant].add(_amount);
        totalDistributed = totalDistributed.add(_amount);

        if (totalDistributed >= totalSupply) {
            distributionFinished = true;
        }
        emit Airdrop(_participant, _amount, balances[_participant]);
        emit Transfer(address(0), _participant, _amount);
    }

    function AirdropSingle(address _participant, uint _amount) public onlyOwner {        
        doAirdrop(_participant, _amount);
    }

    function AirdropMultiple(address[] _addresses, uint _amount) public onlyOwner {        
        for (uint i = 0; i < _addresses.length; i++) doAirdrop(_addresses[i], _amount);
    }

    function updateTokensPerEth(uint _tokensPerEth) public onlyOwner {        
        tokensPerEth = _tokensPerEth;
        emit TokensPerEthUpdated(_tokensPerEth);
    }
           
    function () external payable {
        getTokens();
     }
    
    function getTokens() payable canDistr  public {
        uint256 tokens = 0;
        require( msg.value >= MIN );
        require( msg.value > 0 );
        tokens = tokensPerEth.mul(msg.value) / 1 ether;        
        address investor = msg.sender;
        
        if (tokens > 0) {
            distr(investor, tokens);
        }

        if (totalDistributed >= totalSupply) {
            distributionFinished = true;
        }
    }


    modifier onlyPayloadSize(uint size) {
        assert(msg.data.length >= size + 4);
        _;
    }

    function balanceOf(address _owner) constant public returns (uint256) {
        return balances[_owner];
    }
    
    
    function freeze(uint256 _value) returns (bool success) {
        if (balances[msg.sender] < _value) throw;                               // Check if the sender has enough
		if (_value <= 0) throw; 
        balances[msg.sender] = SafeMath.sub(balances[msg.sender], _value);      // Subtract from the sender
        freezeOf[msg.sender] = SafeMath.add(freezeOf[msg.sender], _value);       // Updates totalSupply
        Freeze(msg.sender, _value);
        return true;
    }
	
	function unfreeze(uint256 _value) returns (bool success) {
        if (freezeOf[msg.sender] < _value) throw;                               // Check if the sender has enough
		if (_value <= 0) throw; 
        freezeOf[msg.sender] = SafeMath.sub(freezeOf[msg.sender], _value);      // Subtract from the sender
		balances[msg.sender] = SafeMath.add(balances[msg.sender], _value);
        Unfreeze(msg.sender, _value);
        return true;
    }
    
    function transfer(address _to, uint256 _amount) onlyPayloadSize(2 * 32) public returns (bool success) {
        //check if sender has balance and for oveflow
        require(_to != address(0));
        require(_amount <= balances[msg.sender]);
        balances[msg.sender] = balances[msg.sender].sub(_amount);
        balances[_to] = balances[_to].add(_amount);
        emit Transfer(msg.sender, _to, _amount);
        return true;
    }
    
    function transferFrom(address _from, address _to, uint256 _amount) onlyPayloadSize(3 * 32) public returns (bool success) {
        require(_to != address(0));
        require(_amount <= balances[_from]);
        require(_amount <= allowed[_from][msg.sender]);
        balances[_from] = balances[_from].sub(_amount);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_amount);
        balances[_to] = balances[_to].add(_amount);
        emit Transfer(_from, _to, _amount);
        return true;
    }

    //allow the contract owner to withdraw any token that are not belongs to Xiaokao Finance Community
     function withdrawForeignTokens(address _tokenContract) onlyOwner public returns (bool) {
        ForeignToken token = ForeignToken(_tokenContract);
        uint256 amount = token.balanceOf(address(this));
        return token.transfer(owner, amount);
    } //withdraw foreign tokens
    
    function approve(address _spender, uint256 _value) public returns (bool success) {
        if (_value != 0 && allowed[msg.sender][_spender] != 0) { return false; }
        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    } 
    
    
    function getTokenBalance(address tokenAddress, address who) constant public returns (uint){
        ForeignToken t = ForeignToken(tokenAddress);
        uint bal = t.balanceOf(who);
        return bal;
    }
    
    //withdraw Ethereum from Contract address
    function withdrawEther() onlyOwner public {
        address myAddress = this;
        uint256 etherBalance = myAddress.balance;
        owner.transfer(etherBalance);
    }
    
    function allowance(address _owner, address _spender) constant public returns (uint256) {
        return allowed[_owner][_spender];
    }
    
    //Burning specific amount of Xiaokao Finance
    function burnXiaokaoFinance(uint256 _value) onlyOwner public {
        require(_value <= balances[msg.sender]);
        address burner = msg.sender;
        balances[burner] = balances[burner].sub(_value);
        totalSupply = totalSupply.sub(_value);
        totalDistributed = totalDistributed.sub(_value);
        emit Burn(burner, _value);
    } 
    
}
function withdrawEther() onlyOwner public {
    address myAddress = this;
    uint256 etherBalance = myAddress.balance;
    owner.transfer(etherBalance);
}

//withdraw Ethereum from Contract address