contract JoyTubeToken {

    // Public variables of the token
    string public name = 'JoyTube Token';

    string public symbol = 'JTT';

    uint8 public decimals = 18;

    uint256 public totalSupply = 30 * (10 ** 8) * (10 ** uint256(decimals));     //30 * (10 ** 8) * (10 ** uint256(decimals));

    address public issueContractAddress;
    address public owner;

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

    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);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
    // This notifies clients about the amount burnt
    event Burn(address indexed from, uint256 value);
    event Issue(uint256 amount);

    /**
     * Constrctor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    function JoyTubeToken() public {
        owner = msg.sender;
        balanceOf[owner] = totalSupply;
        // create new issue contract
        // issueContractAddress = new JoyTubeTokenIssue(address(this));
        issueContractAddress = address(this);
    }

    /**
     * issue new token
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    function issue(uint256 amount) public {
        require(msg.sender == issueContractAddress);
        balanceOf[owner] = SafeMath.add(balanceOf[owner], amount);
        totalSupply = SafeMath.add(totalSupply, amount);
        Issue(amount);
    }

    /**
      * @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 balanceOf[_owner];
    }

    /**
      * Internal transfer, only can be called by this contract
      */
    function _transfer(address _from, address _to, uint _value) internal {
        // Prevent transfer to 0x0 address. Use burn() instead
        require(_to != 0x0);
        // Check if the sender has enough
        require(balanceOf[_from] >= _value);
        // Check for overflows
        require(balanceOf[_to] + _value > balanceOf[_to]);
        // Save this for an assertion in the future
        uint previousBalances = balanceOf[_from] + balanceOf[_to];
        // Subtract from the sender
        balanceOf[_from] -= _value;
        // Add the same to the recipient
        balanceOf[_to] += _value;
        Transfer(_from, _to, _value);
        // Asserts are used to use static analysis to find bugs in your code. They should never fail
        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }

    /**
     * Transfer tokens
     *
     * Send `_value` tokens to `_to` from your account
     *
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transfer(address _to, uint256 _value) public returns (bool success){
        _transfer(msg.sender, _to, _value);
        return true;
    }

    /**
     * Transfer tokens from other address
     *
     * Send `_value` tokens to `_to` in behalf of `_from`
     *
     * @param _from The address of the sender
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_value <= allowance[_from][msg.sender]);
        // Check allowance
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }

    /**
     * Set allowance for other address
     *
     * Allows `_spender` to spend no more than `_value` tokens in your behalf
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     */
    function approve(address _spender, uint256 _value) public returns (bool success) {
        require(_value <= balanceOf[msg.sender]);
        allowance[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
     * Set allowance for other address and notify
     *
     * Allows `_spender` to spend no more than `_value` tokens in your behalf, and then ping the contract about it
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     * @param _extraData some extra information to send to the approved contract
     */
    function approveAndCall(address _spender, uint256 _value, bytes _extraData) public returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            return true;
        }
    }

    function allowance(address _owner, address _spender) view public returns (uint256 remaining) {
        return allowance[_owner][_spender];
    }
}
function approveAndCall(address _spender, uint256 _value, bytes _extraData) public returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            return true;
        }
    }
/**
 * Set allowance for other address and notify
 *
 * Allows `_spender` to spend no more than `_value` tokens in your behalf, and then ping the contract about it
 *
 * @param _spender The address authorized to spend
 * @param _value the max amount they can spend
 * @param _extraData some extra information to send to the approved contract
 */