Token Mining

pragma solidity ^0.4.18;

interface token { function transfer(address receiver, uint amount) external; }

contract Crowdsale { address public beneficiary; uint public fundingGoal; uint public amountRaised; uint public deadline; uint public price; token public tokenReward; mapping(address => uint256) public balanceOf; bool fundingGoalReached = false; bool crowdsaleClosed = false;

event GoalReached(address recipient, uint totalAmountRaised);
event FundTransfer(address backer, uint amount, bool isContribution);

/**
 * Constructor function
 *
 * Setup the owner
 */
function Crowdsale(
    address ifSuccessfulSendTo,
    uint fundingGoalInEthers,
    uint durationInMinutes,
    uint etherCostOfEachToken,
    address addressOfTokenUsedAsReward
) public {
    beneficiary = ifSuccessfulSendTo;
    fundingGoal = fundingGoalInEthers * 1 ether;
    deadline = now + durationInMinutes * 1 minutes;
    price = etherCostOfEachToken * 1 ether;
    tokenReward = token(addressOfTokenUsedAsReward);
}

/**
 * Fallback function
 *
 * The function without name is the default function that is called whenever anyone sends funds to a contract
 */
function () payable public {
    require(!crowdsaleClosed);
    uint amount = msg.value;
    balanceOf[msg.sender] += amount;
    amountRaised += amount;
    tokenReward.transfer(msg.sender, amount / price);
   emit FundTransfer(msg.sender, amount, true);
}

modifier afterDeadline() { if (now >= deadline) _; }

/**
 * Check if goal was reached
 *
 * Checks if the goal or time limit has been reached and ends the campaign
 */
function checkGoalReached() public afterDeadline {
    if (amountRaised >= fundingGoal){
        fundingGoalReached = true;
        emit GoalReached(beneficiary, amountRaised);
    }
    crowdsaleClosed = true;
}


/**
 * Withdraw the funds
 *
 * Checks to see if goal or time limit has been reached, and if so, and the funding goal was reached,
 * sends the entire amount to the beneficiary. If goal was not reached, each contributor can withdraw
 * the amount they contributed.
 */
function safeWithdrawal() public afterDeadline {
    if (!fundingGoalReached) {
        uint amount = balanceOf[msg.sender];
        balanceOf[msg.sender] = 0;
        if (amount > 0) {
            if (msg.sender.send(amount)) {
               emit FundTransfer(msg.sender, amount, false);
            } else {
                balanceOf[msg.sender] = amount;
            }
        }
    }

    if (fundingGoalReached && beneficiary == msg.sender) {
        if (beneficiary.send(amountRaised)) {
           emit FundTransfer(beneficiary, amountRaised, false);
        } else {
            //If we fail to send the funds to beneficiary, unlock funders balance
            fundingGoalReached = false;
        }
    }
}

}