pragma solidity ^0.4.11;
library SafeMath {
  function mul(uint a, uint b) internal returns (uint) {
    uint c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }
  function div(uint a, uint b) internal returns (uint) {
    assert(b > 0);
    uint c = a / b;
    assert(a == b * c + a % b);
    return c;
  }
  function sub(uint a, uint b) internal returns (uint) {
    assert(b <= a);
    return a - b;
  }
  function add(uint a, uint b) internal returns (uint) {
    uint c = a + b;
    assert(c >= a);
    return c;
  }
  function max64(uint64 a, uint64 b) internal constant returns (uint64) {
    return a >= b ? a : b;
  }
  function min64(uint64 a, uint64 b) internal constant returns (uint64) {
    return a < b ? a : b;
  }
  function max256(uint256 a, uint256 b) internal constant returns (uint256) {
    return a >= b ? a : b;
  }
  function min256(uint256 a, uint256 b) internal constant returns (uint256) {
    return a < b ? a : b;
  }
  function assert(bool assertion) internal {
    if (!assertion) {
      throw;
    }
  }
}
contract Ownable {
    address public owner;
    function Ownable() {
        owner = msg.sender;
    }
    modifier onlyOwner {
        if (msg.sender != owner) throw;
        _;
    }
    function transferOwnership(address newOwner) onlyOwner {
        if (newOwner != address(0)) {
            owner = newOwner;
        }
    }
}
/*
 * Pausable
 * Abstract contract that allows children to implement an
 * emergency stop mechanism.
 */
contract Pausable is Ownable {
  bool public stopped;
  modifier stopInEmergency {
    if (stopped) {
      throw;
    }
    _;
  }

  modifier onlyInEmergency {
    if (!stopped) {
      throw;
    }
    _;
  }
  // called by the owner on emergency, triggers stopped state
  function emergencyStop() external onlyOwner {
    stopped = true;
  }
  // called by the owner on end of emergency, returns to normal state
  function release() external onlyOwner onlyInEmergency {
    stopped = false;
  }
}
contract ERC20Basic {
  uint public totalSupply;
  function balanceOf(address who) constant returns (uint);
  function transfer(address to, uint value);
  event Transfer(address indexed from, address indexed to, uint value);
}
contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) constant returns (uint);
  function transferFrom(address from, address to, uint value);
  function approve(address spender, uint value);
  event Approval(address indexed owner, address indexed spender, uint value);
}
/*
 * PullPayment
 * Base contract supporting async send for pull payments.
 * Inherit from this contract and use asyncSend instead of send.
 */
contract PullPayment {
  using SafeMath for uint;

  mapping(address => uint) public payments;
  event LogRefundETH(address to, uint value);
  /**
  *  Store sent amount as credit to be pulled, called by payer
  **/
  function asyncSend(address dest, uint amount) internal {
    payments[dest] = payments[dest].add(amount);
  }
  // withdraw accumulated balance, called by payee
  function withdrawPayments() {
    address payee = msg.sender;
    uint payment = payments[payee];

    if (payment == 0) {
      throw;
    }
    if (this.balance < payment) {
      throw;
    }
    payments[payee] = 0;
    if (!payee.send(payment)) {
      throw;
    }
    LogRefundETH(payee,payment);
  }
}
contract BasicToken is ERC20Basic {

  using SafeMath for uint;

  mapping(address => uint) balances;

  /*
   * Fix for the ERC20 short address attack
  */
  modifier onlyPayloadSize(uint size) {
     if(msg.data.length < size + 4) {
       throw;
     }
     _;
  }
  function transfer(address _to, uint _value) onlyPayloadSize(2 * 32) {
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    Transfer(msg.sender, _to, _value);
  }
  function balanceOf(address _owner) constant returns (uint balance) {
    return balances[_owner];
  }
}
contract StandardToken is BasicToken, ERC20 {
  mapping (address => mapping (address => uint)) allowed;
  function transferFrom(address _from, address _to, uint _value) onlyPayloadSize(3 * 32) {
    var _allowance = allowed[_from][msg.sender];
    // Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
    // if (_value > _allowance) throw;
    balances[_to] = balances[_to].add(_value);
    balances[_from] = balances[_from].sub(_value);
    allowed[_from][msg.sender] = _allowance.sub(_value);
    Transfer(_from, _to, _value);
  }
  function approve(address _spender, uint _value) {
    // To change the approve amount you first have to reduce the addresses`
    //  allowance to zero by calling `approve(_spender, 0)` if it is not
    //  already 0 to mitigate the race condition described here:
    //  https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
    if ((_value != 0) && (allowed[msg.sender][_spender] != 0)) throw;
    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
  }
  function allowance(address _owner, address _spender) constant returns (uint remaining) {
    return allowed[_owner][_spender];
  }
}
/**
 *  manus token contract. Implements
 */
contract Utcoin is StandardToken, Ownable {
  string public constant name = "UTOPIA";
  string public constant symbol = "utcoin";
  uint public constant decimals = 8;
  // Constructor
  function Utcoin() {
      totalSupply =10000000000000000 ;
      balances[msg.sender] = totalSupply; // Send all tokens to owner
  }
  /**
   *  Burn away the specified amount of utcoin tokens
   */
  function burn(uint _value) onlyOwner returns (bool) {
    balances[msg.sender] = balances[msg.sender].sub(_value);
    totalSupply = totalSupply.sub(_value);
    Transfer(msg.sender, 0x0, _value);
    return true;
  }
}
/*
  This smart contract collects ETH, and in return emits utcoin tokens to the backers
*/
contract Crowdsale is Pausable, PullPayment {

    using SafeMath for uint;

  	struct Backer {
		uint weiReceived; // Amount of Ether given
		uint utcoinSent;
	}

	/*
	* Constants
	*/
	/* Minimum number of manus to sell */
	uint public constant MIN_CAP = 5000000000000000;
	/* Maximum number of manus to sell */
	uint public constant MAX_CAP =8000000000000000 ;
  /* Crowdsale period */
	uint private constant CROWDSALE_PERIOD = 120 days;
  /* Number of utcoin per Ether */
	uint public constant UTCOIN_PER_ETHER = 45500000000;

	/*
	* Variables
	*/
	/* Utcoin contract reference */
	Utcoin public utcoin;
    /* Multisig contract that will receive the Ether */
	address public multisigEther;
	/* Number of Ether received */
	uint public etherReceived;
	/* Number of utcoin sent to Ether contributors */
	uint public utcoinSentToEther;
  /* 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) || utcoinSentToEther >= MIN_CAP ) throw;
		_;
	}

	modifier respectTimeFrame() {
		if ((now < startTime) || (now > endTime )) throw;
		_;
	}

	/*
	 * Event
	*/
	event LogReceivedETH(address addr, uint value);
	event LogUtcoinEmited(address indexed from, uint amount);

	/*
	 * Constructor
	*/
	function Crowdsale(address _utcoinAddress, address _to) {
		utcoin = Utcoin(_utcoinAddress);
		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 {

		uint utcoinToSend = bonus(msg.value.mul(UTCOIN_PER_ETHER).div(1 ether)); // Compute the number of utcoin to send
		if (utcoinToSend.add(utcoinSentToEther) > MAX_CAP) throw;

		Backer backer = backers[beneficiary];
		utcoin.transfer(beneficiary, utcoinToSend); // Transfer utcoin right now

		backer.utcoinSent = backer.utcoinSent.add(utcoinToSend);
		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
		utcoinSentToEther = utcoinSentToEther.add(utcoinToSend);

		// Send events
		LogUtcoinEmited(msg.sender ,utcoinToSend);
		LogReceivedETH(beneficiary, etherReceived);
	}


	/*
	 *Compute the utcoin bonus according to the investment period
	 */
	function bonus(uint amount) internal constant returns (uint) {
		if (now < startTime.add(2 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 manus
			if (utcoinSentToEther == MAX_CAP) {
			} else {
				throw;
			}
		}

		if (utcoinSentToEther < 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 = utcoin.balanceOf(this);
		if (remains > 0) { // Burn the rest of utcoin
			if (!utcoin.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 utcoin owner address.
	 */
	function backUtcoinOwner() onlyOwner public {
		utcoin.transferOwnership(owner);
	}

	/**
	 * Transfer remains to owner in case if impossible to do min invest
	 */
	function getRemainUtcoin() onlyOwner public {
		var remains = MAX_CAP - utcoinSentToEther;
		uint minUtcoinToSell = bonus((UTCOIN_PER_ETHER) / (1 ether));

		if(remains > minUtcoinToSell) throw;

		Backer backer = backers[owner];
		utcoin.transfer(owner, remains); // Transfer utcoin right now

		backer.utcoinSent = backer.utcoinSent.add(remains);

		utcoinSentToEther = utcoinSentToEther.add(remains);

		// Send events
		LogUtcoinEmited(this ,remains);
		LogReceivedETH(owner, etherReceived);
	}


	/*
  	 * When MIN_CAP is not reach:
  	 * 1) backer call the "approve" function of the utcoin token contract with the amount of all utcoin they got in order to be refund
  	 * 2) backer call the "refund" function of the Crowdsale contract with the same amount of utcoin
   	 * 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].utcoinSent) throw; // compare value from backer balance

		utcoin.transferFrom(msg.sender, address(this), _value); // get the token back to the crowdsale contract

		if (!utcoin.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
		}
	}

}