contract Crowdsale {
    using SafeMath for uint256;

    // The token being sold
    SignalsToken public token;

    // address where funds are collected
    address public wallet;

    // amount of raised money in wei
    uint256 public weiRaised;

    // start/end related 
    uint256 public startTime;
    bool public hasEnded;

    /**
     * event for token purchase logging
     * @param purchaser who paid for the tokens
     * @param beneficiary who got the tokens
     * @param value weis paid for purchase
     * @param amount amount of tokens purchased
     */
    event TokenPurchase(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);

    function Crowdsale(address _token, address _wallet) public {
        require(_wallet != 0x0);
        token = SignalsToken(_token);
        wallet = _wallet;
    }

    // fallback function can be used to buy tokens
    function () public payable {
        buyTokens(msg.sender);
    }

    // low level token purchase function
    function buyTokens(address beneficiary) private {}

    // send ether to the fund collection wallet
    // override to create custom fund forwarding mechanisms
    function forwardFunds() internal {
        wallet.transfer(msg.value);
    }

    // @return true if the transaction can buy tokens
    function validPurchase() internal constant returns (bool) {}

}
/**
 * @title Crowdsale
 * @dev Crowdsale is a base contract for managing a token crowdsale.
 * Crowdsales have a start and end timestamps, where investors can make
 * token purchases and the crowdsale will assign them tokens based
 * on a token per ETH rate. Funds collected are forwarded to a wallet
 * as they arrive.
 */
function () public payable {
    buyTokens(msg.sender);
}

// fallback function can be used to buy tokens