pragma solidity ^0.4.24;
// This contract has the burn option
interface token {
    function transfer(address receiver, uint amount);
    function burn(uint256 _value) returns (bool);
    function balanceOf(address _address) returns (uint256);
}
contract owned { //Contract used to only allow the owner to call some functions
	address public owner;

	function owned() public {
	owner = msg.sender;
	}

	modifier onlyOwner {
	require(msg.sender == owner);
	_;
	}

	function transferOwnership(address newOwner) onlyOwner public {
	owner = newOwner;
	}
}

contract SafeMath {
    //internals

    function safeMul(uint a, uint b) internal returns(uint) {
        uint c = a * b;
        assert(a == 0 || c / a == b);
        return c;
    }

    function safeSub(uint a, uint b) internal returns(uint) {
        assert(b <= a);
        return a - b;
    }

    function safeAdd(uint a, uint b) internal returns(uint) {
        uint c = a + b;
        assert(c >= a && c >= b);
        return c;
    }

}

contract Crowdsale is owned, SafeMath {
    address public beneficiary;
    uint public fundingGoal;
    uint public amountRaised;  //The amount being raised by the crowdsale
    /* the end date of the crowdsale*/
    uint public deadline; /* the end date of the crowdsale*/
    uint public rate; //rate for the crowdsale
    uint public tokenDecimals;
    token public tokenReward; //
    uint public tokensSold = 0;  //the amount of UzmanbuCoin sold  
    /* the start date of the crowdsale*/
    uint public start; /* the start date of the crowdsale*/
    mapping(address => uint256) public balanceOf;  //Ether deposited by the investor
    // bool fundingGoalReached = false;
    bool crowdsaleClosed = false; //It will be true when the crowsale gets closed

    event GoalReached(address beneficiary, uint capital);
    event FundTransfer(address backer, uint amount, bool isContribution);

    /**
     * Constrctor function
     *
     * Setup the owner
     */
    function Crowdsale( ) {
        beneficiary = 0xE579891b98a3f58E26c4B2edB54E22250899363c;
        rate = 40000; //
        tokenDecimals=8;
        fundingGoal = 2500000000 * (10 ** tokenDecimals); 
        start = 1536537600; 
        deadline =1539129600; 
        tokenReward = token(0x19335137283563C9531062EDD04ddf19d42097bd); //Token address. Modify by the current token address
    }    

    /**
     * Fallback function
     *
     * The function without name is the default function that is called whenever anyone sends funds to a contract
     */
     /*
   
     */
    function () payable {
        uint amount = msg.value;  //amount received by the contract
        uint numTokens; //number of token which will be send to the investor
        numTokens = getNumTokens(amount);   //It will be true if the soft capital was reached
        require(numTokens>0 && !crowdsaleClosed && now > start && now < deadline);
        balanceOf[msg.sender] = safeAdd(balanceOf[msg.sender], amount);
        amountRaised = safeAdd(amountRaised, amount); //Amount raised increments with the amount received by the investor
        tokensSold += numTokens; //Tokens sold increased too
        tokenReward.transfer(msg.sender, numTokens); //The contract sends the corresponding tokens to the investor
        beneficiary.transfer(amount);               //Forward ether to beneficiary
        FundTransfer(msg.sender, amount, true);
    }
    /*
    It calculates the amount of tokens to send to the investor 
    */
    function getNumTokens(uint _value) internal returns(uint numTokens) {
        require(_value>=10000000000000000 * 1 wei); //Min amount to invest: 0.01 ETH
        numTokens = safeMul(_value,rate)/(10 ** tokenDecimals); //Number of tokens to give is equal to the amount received by the rate 
        return numTokens;
    }

    function changeBeneficiary(address newBeneficiary) onlyOwner {
        beneficiary = newBeneficiary;
    }

    modifier afterDeadline() { if (now >= deadline) _; }

    /**
     * Check if goal was reached
     *
     * Checks if the goal or time limit has been reached and ends the campaign and burn the tokens
     */
    function checkGoalReached() afterDeadline {
        require(msg.sender == owner); //Checks if the one who executes the function is the owner of the contract
        if (tokensSold >=fundingGoal){
            GoalReached(beneficiary, amountRaised);
        }
        tokenReward.burn(tokenReward.balanceOf(this)); //Burns all the remaining tokens in the contract 
        crowdsaleClosed = true; //The crowdsale gets closed if it has expired
    }



}