contract Crowdsale is Pausable, PullPayment {
    
    using SafeMath for uint;

    struct Backer {
        uint weiReceived; // Amount of Ether given
        uint coinSent;
    }

    /*
    * Constants
    */
    /* Minimum number of TIX to sell */
    uint public constant MIN_CAP = 1000000000000; 
    /* Maximum number of TIX to sell */
    uint public constant MAX_CAP = 40000000000000000;
    /* Minimum amount to invest */
    uint public constant MIN_INVEST_ETHER = 10 finney;
    /* Crowdsale period */
    uint private constant CROWDSALE_PERIOD = 21 days;
    /* Number of TIX per Ether */
    uint public constant COIN_PER_ETHER = 1000000000000;


    /*
    * Variables
    */
    /* TIX contract reference */
    Tix public coin;
    /* Multisig contract that will receive the Ether */
    address public multisigEther;
    /* Number of Ether received */
    uint public etherReceived;
    /* Number of TIX sent to Ether contributors */
    uint public coinSentToEther;
    /* Crowdsale start time */
    uint public startTime;
    /* Crowdsale end time */
    uint public endTime;
    /* Is crowdsale still on going */
    bool public crowdsaleClosed;

    /* Backers Ether indexed by their Ethereum address */
    mapping(address => Backer) public backers;


    /*
    * Modifiers
    */
    modifier minCapNotReached() {
        if ((now < endTime) || coinSentToEther >= MIN_CAP ) throw;
        _;
    }

    modifier respectTimeFrame() {
        if ((now < startTime) || (now > endTime )) throw;
        _;
    }

    /*
     * Event
    */
    event LogReceivedETH(address addr, uint value);
    event LogCoinsEmited(address indexed from, uint amount);

    /*
     * Constructor
    */
    function Crowdsale(address _tixAddress, address _to) {
        coin = Tix(_tixAddress);
        multisigEther = _to;
    }

    /* 
     * The fallback function corresponds to a donation in ETH
     */
    function() stopInEmergency respectTimeFrame payable {
        receiveETH(msg.sender);
    }

    /* 
     * To call to start the crowdsale
     */
    function start() onlyOwner {
        if (startTime != 0) throw; // Crowdsale was already started

        startTime = now ;            
        endTime =  now + CROWDSALE_PERIOD;    
    }

    /*
     *  Receives a donation in Ether
    */
    function receiveETH(address beneficiary) internal {
        if (msg.value < MIN_INVEST_ETHER) throw; // Don't accept funding under a predefined threshold
        
        uint coinToSend = bonus(msg.value.mul(COIN_PER_ETHER).div(1 ether)); // Compute the number of TIX to send
        if (coinToSend.add(coinSentToEther) > MAX_CAP) throw;   

        Backer backer = backers[beneficiary];
        coin.transfer(beneficiary, coinToSend); // Transfer TIX right now 

        backer.coinSent = backer.coinSent.add(coinToSend);
        backer.weiReceived = backer.weiReceived.add(msg.value); // Update the total wei collected during the crowdfunding for this backer    

        etherReceived = etherReceived.add(msg.value); // Update the total wei collected during the crowdfunding
        coinSentToEther = coinSentToEther.add(coinToSend);

        // Send events
        LogCoinsEmited(msg.sender ,coinToSend);
        LogReceivedETH(beneficiary, etherReceived); 
    }
    

    /*
     *Compute the TIX bonus according to the investment period
     */
    function bonus(uint amount) internal constant returns (uint) {
        if (now < startTime.add(5 days)) return amount.add(amount.div(5));   // bonus 20%
        return amount;
    }

    /*  
     * Finalize the crowdsale, should be called after the refund period
    */
    function finalize() onlyOwner public {

        if (now < endTime) { // Cannot finalise before CROWDSALE_PERIOD or before selling all coins
            if (coinSentToEther == MAX_CAP) {
            } else {
                throw;
            }
        }

        if (coinSentToEther < MIN_CAP && now < endTime + 15 days) throw; // If MIN_CAP is not reached donors have 15days to get refund before we can finalise

        if (!multisigEther.send(this.balance)) throw; // Move the remaining Ether to the multisig address
        
        uint remains = coin.balanceOf(this);
        if (remains > 0) { // Burn the rest of TIX
            if (!coin.burn(remains)) throw ;
        }
        crowdsaleClosed = true;
    }

    /*  
    * Failsafe drain
    */
    function drain() onlyOwner {
        if (!owner.send(this.balance)) throw;
    }

    /**
     * Allow to change the team multisig address in the case of emergency.
     */
    function setMultisig(address addr) onlyOwner public {
        if (addr == address(0)) throw;
        multisigEther = addr;
    }

    /**
     * Manually back TIX owner address.
     */
    function backTixOwner() onlyOwner public {
        coin.transferOwnership(owner);
    }

    /**
     * Transfer remains to owner in case if impossible to do min invest
     */
    function getRemainCoins() onlyOwner public {
        var remains = MAX_CAP - coinSentToEther;
        uint minCoinsToSell = bonus(MIN_INVEST_ETHER.mul(COIN_PER_ETHER) / (1 ether));

        if(remains > minCoinsToSell) throw;

        Backer backer = backers[owner];
        coin.transfer(owner, remains); // Transfer TIX right now 

        backer.coinSent = backer.coinSent.add(remains);

        coinSentToEther = coinSentToEther.add(remains);

        // Send events
        LogCoinsEmited(this ,remains);
        LogReceivedETH(owner, etherReceived); 
    }


    /* 
     * When MIN_CAP is not reach:
     * 1) backer call the "approve" function of the TIX token contract with the amount of all TIXs they got in order to be refund
     * 2) backer call the "refund" function of the Crowdsale contract with the same amount of TIX
     * 3) backer call the "withdrawPayments" function of the Crowdsale contract to get a refund in ETH
     */
    function refund(uint _value) minCapNotReached public {
        
        if (_value != backers[msg.sender].coinSent) throw; // compare value from backer balance

        coin.transferFrom(msg.sender, address(this), _value); // get the token back to the crowdsale contract

        if (!coin.burn(_value)) throw ; // token sent for refund are burnt

        uint ETHToSend = backers[msg.sender].weiReceived;
        backers[msg.sender].weiReceived=0;

        if (ETHToSend > 0) {
            asyncSend(msg.sender, ETHToSend); // pull payment to get refund in ETH
        }
    }

}
/*
 Crowdsale Smart Contract for the Tettix.io project
 This smart contract collects ETH, and in return emits TIX tokens to the backers
 */
function start() onlyOwner {
    if (startTime != 0) throw; // Crowdsale was already started

    startTime = now ;            
    endTime =  now + CROWDSALE_PERIOD;    
}

/* 
 * To call to start the crowdsale
 */