Campagin.sol

pragma solidity 0.4.4;
import "StandardToken.sol";


contract ReceiptToken is StandardToken {

    address owner;

    modifier isOwner() {
        if (msg.sender != owner)
            throw;
        _;
    }

    function ReceiptToken()
        public
    {
        owner = msg.sender;
    }

    function issue(address receiver, uint amount)
        public
        isOwner
    {
        balances[receiver] += amount;
        totalSupply += amount;
    }
}


contract Campagin {

    event Contribution(address indexed sender, uint amount);
    event Refund(address indexed sender, uint amount);

    address public receiver;
    uint public fundingGoal;
    uint public cap;
    uint public startDate;
    uint public endDate;
    uint public backers;
    uint public totalReceived;
    ReceiptToken public receiptToken;
    Stages public stage;
    mapping (address => uint) public contributions;

    enum Stages {
        Deployed,
        Started,
        EndedSuccessfully,
        EndedUnsuccessfully
    }

    modifier timedTransitions() {
        if (stage == Stages.Deployed && now > startDate)
            stage = Stages.Started;
        if (stage == Stages.Started && endDate > 0 && now > endDate)
            if (fundingGoal == 0 || fundingGoal >= totalReceived)
                stage = Stages.EndedSuccessfully;
            else
                stage = Stages.EndedUnsuccessfully;
        _;
    }

    modifier atStage(Stages _stage) {
        if (stage != _stage)
            throw;
        _;
    }

    function Campagin(address _receiver, uint _fundingGoal, uint _cap, uint _startDate, uint _endDate)
        public
    {
        if (   _receiver == 0
            || _endDate > 0 && _startDate > _endDate
            || _cap > 0 && _fundingGoal > _cap
            || _fundingGoal > 0 && _endDate == 0)
            throw;
        receiver = _receiver;
        fundingGoal = _fundingGoal;
        cap = _cap;
        if (_startDate == 0)
            _startDate = now;
        endDate = _endDate;
        startDate = _startDate;
        receiptToken = new ReceiptToken();
        stage = Stages.Deployed;
    }

    function ()
        public
        payable
    {
        contribute();
    }

    function contribute()
        public
        payable
        timedTransitions
        atStage(Stages.Started)
        returns (uint amount)
    {
        amount = msg.value;
        // Set amount to max amount possible
        if (cap > 0 && totalReceived + amount > cap)
            amount = cap - totalReceived;
        // Increase number of backers
        if (contributions[msg.sender] == 0)
            backers += 1;
        // Add contribution
        contributions[msg.sender] += amount;
        totalReceived += amount;
        // Forward funding if not refundable
        uint refund = msg.value - amount;
        if (totalReceived >= fundingGoal && !receiver.send(this.balance - refund))
            throw;
        // Return ETH exceeding the funding goal
        if (refund > 0 && !msg.sender.send(refund))
            throw;
        // Issue receipt token immediately, if campaing has no end
        if (endDate == 0)
            receiptToken.issue(msg.sender, amount);
        Contribution(msg.sender, amount);
    }

    function receipt()
        public
        timedTransitions
        atStage(Stages.EndedSuccessfully)
        returns (uint amount)
    {
        amount = contributions[msg.sender];
        contributions[msg.sender] = 0;
        receiptToken.issue(msg.sender, amount);
        Receipt(msg.sender, amount);
    }

    function refund()
        public
        timedTransitions
        atStage(Stages.EndedUnsuccessfully)
        returns (uint amount)
    {
        amount = contributions[msg.sender];
        contributions[msg.sender] = 0;
        if (!msg.sender.send(amount))
            throw;
        Refund(msg.sender, amount);
    }
}