pragma solidity ^0.4.21;


  /**
   * @title  SafeMath
   * @dev  Math operations with safety checks that throw on error
   */
  library SafeMath {
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
      if (a == 0) {
        return 0;
      }
      uint256 c = a * b;
      assert(c / a == b);
      return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
      // assert(b > 0); // Solidity automatically throws when dividing by 0
      uint256 c = a / b;
      // assert(a == b * c + a % b); // There is no case in which this doesn't hold
      return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
      assert(b <= a);
      return a - b;
    }

    function add(uint256 a, uint256 b) internal pure returns (uint256) {
      uint256 c = a + b;
      assert(c >= a);
      return c;
    }
  }
  /**
   * @title  Ownable
   * @dev  The Ownable contract has an owner address, and provides basic authorization control
   * functions, this simplifies the implementation of "user permissions".
   */
  contract Ownable {
    address public owner;


    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);


    /**
     * @dev  The Ownable constructor sets the original `owner` of the contract to the sender
     * account.
     */
    function Ownable() public {
      owner = msg.sender;
    }

    /**
     * @dev  Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
      require(msg.sender == owner);
      _;
    }

    /**
     * @dev  Allows the current owner to transfer control of the contract to a newOwner.
     * @param  newOwner The address to transfer ownership to.
     */
    function transferOwnership(address newOwner) public onlyOwner {
      require(newOwner != address(0));
      emit OwnershipTransferred(owner, newOwner);
      owner = newOwner;
    }

  }

  interface TokenInterface {
       function totalSupply() external constant returns (uint);
       function balanceOf(address tokenOwner) external constant returns (uint balance);
       function allowance(address tokenOwner, address spender) external constant returns (uint remaining);
       function transfer(address to, uint tokens) external returns (bool success);
       function approve(address spender, uint tokens) external returns (bool success);
       function transferFrom(address from, address to, uint tokens) external returns (bool success);
       function burn(uint256 _value) external; 
       event Transfer(address indexed from, address indexed to, uint tokens);
       event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
       event Burn(address indexed burner, uint256 value);
  }

   contract PVCCrowdsale is Ownable{
    using SafeMath for uint256;
   
    // The token being sold
    TokenInterface public token;

    // start and end timestamps where investments are allowed (both inclusive)
    uint256 public startTime;
    uint256 public endTime;


    // how many token units a buyer gets per wei
    uint256 public ratePerWei = 1000;

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

    uint256 public TOKENS_SOLD;
    
    uint256 maxTokensToSale;
    uint256 TokensForTeamVesting;
    uint256 TokensForAdvisorVesting;
    uint256 bonusInPreSalePhase1;
    uint256 bonusInPreSalePhase2;
    uint256 bonusInPublicSalePhase1;
    uint256 bonusInPublicSalePhase2;
    uint256 bonusInPublicSalePhase3;
    uint256 bonusInPublicSalePhase4;
    uint256 bonusInPublicSalePhase5;
    uint256 bonusInPublicSalePhase6;
    
    bool isCrowdsalePaused = false;
    
    uint256 totalDurationInDays = 145 days;
    mapping(address=>bool) isAddressWhiteListed;
    /**
     * 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 PVCCrowdsale(uint256 _startTime, address _wallet, address _tokenAddress) public 
    {
      
      require(_wallet != 0x0);
      startTime = _startTime;  
      endTime = startTime + totalDurationInDays;
      require(endTime >= startTime);
     
      owner = _wallet;
      
      maxTokensToSale = 32500000 * 10 ** 18;
      TOKENS_SOLD = 346018452900000000000;    // the tokens that have been sold through the previous contract
                     
      weiRaised = 285373570000000000;     // the weis that have been raised through the previous contract

      bonusInPreSalePhase1 = 30;
      bonusInPreSalePhase2 = 25;
      bonusInPublicSalePhase1 = 20;
      bonusInPublicSalePhase2 = 25;
      bonusInPublicSalePhase3 = 20;
      bonusInPublicSalePhase4 = 15;
      bonusInPublicSalePhase5 = 10;
      bonusInPublicSalePhase6 = 5;
      
      TokensForTeamVesting = 7000000 * 10 ** 18;
      TokensForAdvisorVesting = 3000000 * 10 ** 18;
      token = TokenInterface(_tokenAddress);
    }
    
    
    // fallback function can be used to buy tokens
    function () public  payable {
      buyTokens(msg.sender);
    }
      
    function determineBonus(uint tokens) internal view returns (uint256 bonus) 
    {
          uint256 timeElapsed = now - startTime;
          uint256 timeElapsedInDays = timeElapsed.div(1 days);
          
          //Closed pre-sale phase 1 (8 days starting apr 9)
          if (timeElapsedInDays <8)
          {
              bonus = tokens.mul(bonusInPreSalePhase1); 
              bonus = bonus.div(100);
              require (TOKENS_SOLD.add(tokens.add(bonus)) <= maxTokensToSale);
          }
          //Closed pre-sale phase 2 (8 days starting apr 17)
          else if (timeElapsedInDays >=8 && timeElapsedInDays <16)
          {
              bonus = tokens.mul(bonusInPreSalePhase2); 
              bonus = bonus.div(100);
              require (TOKENS_SOLD.add(tokens.add(bonus)) <= maxTokensToSale);
          }
          //Public sale phase 1 original (30 days starting on apr 25)
          //Public sale phase 1 new (10 days ending may 4)
          else if (timeElapsedInDays >=16 && timeElapsedInDays <26)
          {
              bonus = tokens.mul(bonusInPublicSalePhase1); 
              bonus = bonus.div(100);
              require (TOKENS_SOLD.add(tokens.add(bonus)) <= maxTokensToSale);
          }

          //Public sale phase 2 (27 days)
          else if (timeElapsedInDays >=26 && timeElapsedInDays <53)
          {
              bonus = tokens.mul(bonusInPublicSalePhase2); 
              bonus = bonus.div(100);
              require (TOKENS_SOLD.add(tokens.add(bonus)) <= maxTokensToSale);
          }

           //Public sale phase 3 (30 days)
          else if (timeElapsedInDays >=53 && timeElapsedInDays <83)
          {
              bonus = tokens.mul(bonusInPublicSalePhase3); 
              bonus = bonus.div(100);
              require (TOKENS_SOLD.add(tokens.add(bonus)) <= maxTokensToSale);
          }
          //Public sale phase 4 (15 days)
          else if (timeElapsedInDays >=83 && timeElapsedInDays <98)
          {
              bonus = tokens.mul(bonusInPublicSalePhase4); 
              bonus = bonus.div(100);
              require (TOKENS_SOLD.add(tokens.add(bonus)) <= maxTokensToSale);
          }
          //Public sale phase 5 (16 days)
          else if (timeElapsedInDays >=98 && timeElapsedInDays <114)
          {
              bonus = tokens.mul(bonusInPublicSalePhase5); 
              bonus = bonus.div(100);
              require (TOKENS_SOLD.add(tokens.add(bonus)) <= maxTokensToSale);
          }
          //Public sale phase 6 (31 days)
          else if (timeElapsedInDays >=114 && timeElapsedInDays <145)
          {
              bonus = tokens.mul(bonusInPublicSalePhase6); 
              bonus = bonus.div(100);
              require (TOKENS_SOLD.add(tokens.add(bonus)) <= maxTokensToSale);
          }
          //
          else 
          {
              bonus = 0;
          }


      }
    // low level token purchase function
    
    function buyTokens(address beneficiary) public payable {
      require(beneficiary != 0x0);
      require(isCrowdsalePaused == false);
      require(validPurchase());
      
      require(TOKENS_SOLD= startTime && now <= endTime;
      bool nonZeroPurchase = msg.value != 0;
      return withinPeriod && nonZeroPurchase;
    }

    // @return  true if crowdsale event has ended
    function hasEnded() public constant returns (bool) {
      return now > endTime;
    }
    
     /**
      * function to change the end timestamp of the ico
      * can only be called by owner wallet
      **/
      function changeEndDate(uint256 endTimeUnixTimestamp) public onlyOwner{
          endTime = endTimeUnixTimestamp;
      }
      
      /**
      * function to change the start timestamp of the ico
      * can only be called by owner wallet
      **/
      
      function changeStartDate(uint256 startTimeUnixTimestamp) public onlyOwner{
          startTime = startTimeUnixTimestamp;
      }
      
      /**
      * function to change the rate of tokens
      * can only be called by owner wallet
      **/
      function setPriceRate(uint256 newPrice) public onlyOwner {
          ratePerWei = newPrice;
      }
      
       /**
       * function to pause the crowdsale 
       * can only be called from owner wallet
       **/
       
      function pauseCrowdsale() public onlyOwner {
          isCrowdsalePaused = true;
      }

      /**
       * function to resume the crowdsale if it is paused
       * can only be called from owner wallet
       **/ 
      function resumeCrowdsale() public onlyOwner {
          isCrowdsalePaused = false;
      }
      
       /**
        * function through which owner can take back the tokens from the contract
        **/ 
       function takeTokensBack() public onlyOwner
       {
           uint remainingTokensInTheContract = token.balanceOf(address(this));
           token.transfer(owner,remainingTokensInTheContract);
       }
       
       /**
        * once the ICO has ended, owner can send all the unsold tokens to treasury address 
        **/ 
       function sendUnsoldTokensToTreasury(address treasury) public onlyOwner
       {
           require(hasEnded());
           uint remainingTokensInTheContract = token.balanceOf(address(this));
           token.transfer(treasury,remainingTokensInTheContract);
       }
  }