pragma solidity ^0.4.21;

// File: zeppelin-solidity/contracts/math/SafeMath.sol

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  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;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  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;
  }

  /**
  * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}

// File: zeppelin-solidity/contracts/token/ERC20/ERC20Basic.sol

/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/179
 */
contract ERC20Basic {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}

// File: zeppelin-solidity/contracts/token/ERC20/BasicToken.sol

/**
 * @title Basic token
 * @dev Basic version of StandardToken, with no allowances.
 */
contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) balances;

  uint256 totalSupply_;

  /**
  * @dev total number of tokens in existence
  */
  function totalSupply() public view returns (uint256) {
    return totalSupply_;
  }

  /**
  * @dev transfer token for a specified address
  * @param _to The address to transfer to.
  * @param _value The amount to be transferred.
  */
  function transfer(address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[msg.sender]);

    // SafeMath.sub will throw if there is not enough balance.
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    Transfer(msg.sender, _to, _value);
    return true;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param _owner The address to query the the balance of.
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address _owner) public view returns (uint256 balance) {
    return balances[_owner];
  }

}

// File: zeppelin-solidity/contracts/token/ERC20/BurnableToken.sol

/**
 * @title Burnable Token
 * @dev Token that can be irreversibly burned (destroyed).
 */
contract BurnableToken is BasicToken {

  event Burn(address indexed burner, uint256 value);

  /**
   * @dev Burns a specific amount of tokens.
   * @param _value The amount of token to be burned.
   */
  function burn(uint256 _value) public {
    require(_value <= balances[msg.sender]);
    // no need to require value <= totalSupply, since that would imply the
    // sender's balance is greater than the totalSupply, which *should* be an assertion failure

    address burner = msg.sender;
    balances[burner] = balances[burner].sub(_value);
    totalSupply_ = totalSupply_.sub(_value);
    Burn(burner, _value);
    Transfer(burner, address(0), _value);
  }
}

// File: zeppelin-solidity/contracts/ownership/Ownable.sol

/**
 * @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));
    OwnershipTransferred(owner, newOwner);
    owner = newOwner;
  }

}

// File: zeppelin-solidity/contracts/token/ERC20/ERC20.sol

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) public view returns (uint256);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: zeppelin-solidity/contracts/token/ERC20/StandardToken.sol

/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * @dev https://github.com/ethereum/EIPs/issues/20
 * @dev Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract StandardToken is ERC20, BasicToken {

  mapping (address => mapping (address => uint256)) internal allowed;


  /**
   * @dev Transfer tokens from one address to another
   * @param _from address The address which you want to send tokens from
   * @param _to address The address which you want to transfer to
   * @param _value uint256 the amount of tokens to be transferred
   */
  function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    Transfer(_from, _to, _value);
    return true;
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   *
   * Beware that changing an allowance with this method brings the risk that someone may use both the old
   * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
   * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
   * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
   * @param _spender The address which will spend the funds.
   * @param _value The amount of tokens to be spent.
   */
  function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
    return true;
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param _owner address The address which owns the funds.
   * @param _spender address The address which will spend the funds.
   * @return A uint256 specifying the amount of tokens still available for the spender.
   */
  function allowance(address _owner, address _spender) public view returns (uint256) {
    return allowed[_owner][_spender];
  }

  /**
   * @dev Increase the amount of tokens that an owner allowed to a spender.
   *
   * approve should be called when allowed[_spender] == 0. To increment
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param _spender The address which will spend the funds.
   * @param _addedValue The amount of tokens to increase the allowance by.
   */
  function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
    allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

  /**
   * @dev Decrease the amount of tokens that an owner allowed to a spender.
   *
   * approve should be called when allowed[_spender] == 0. To decrement
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param _spender The address which will spend the funds.
   * @param _subtractedValue The amount of tokens to decrease the allowance by.
   */
  function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
    uint oldValue = allowed[msg.sender][_spender];
    if (_subtractedValue > oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    }
    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

}

// File: zeppelin-solidity/contracts/token/ERC20/MintableToken.sol

/**
 * @title Mintable token
 * @dev Simple ERC20 Token example, with mintable token creation
 * @dev Issue: * https://github.com/OpenZeppelin/zeppelin-solidity/issues/120
 * Based on code by TokenMarketNet: https://github.com/TokenMarketNet/ico/blob/master/contracts/MintableToken.sol
 */
contract MintableToken is StandardToken, Ownable {
  event Mint(address indexed to, uint256 amount);
  event MintFinished();

  bool public mintingFinished = false;


  modifier canMint() {
    require(!mintingFinished);
    _;
  }

  /**
   * @dev Function to mint tokens
   * @param _to The address that will receive the minted tokens.
   * @param _amount The amount of tokens to mint.
   * @return A boolean that indicates if the operation was successful.
   */
  function mint(address _to, uint256 _amount) onlyOwner canMint public returns (bool) {
    totalSupply_ = totalSupply_.add(_amount);
    balances[_to] = balances[_to].add(_amount);
    Mint(_to, _amount);
    Transfer(address(0), _to, _amount);
    return true;
  }

  /**
   * @dev Function to stop minting new tokens.
   * @return True if the operation was successful.
   */
  function finishMinting() onlyOwner canMint public returns (bool) {
    mintingFinished = true;
    MintFinished();
    return true;
  }
}

// File: zeppelin-solidity/contracts/token/ERC20/CappedToken.sol

/**
 * @title Capped token
 * @dev Mintable token with a token cap.
 */
contract CappedToken is MintableToken {

  uint256 public cap;

  function CappedToken(uint256 _cap) public {
    require(_cap > 0);
    cap = _cap;
  }

  /**
   * @dev Function to mint tokens
   * @param _to The address that will receive the minted tokens.
   * @param _amount The amount of tokens to mint.
   * @return A boolean that indicates if the operation was successful.
   */
  function mint(address _to, uint256 _amount) onlyOwner canMint public returns (bool) {
    require(totalSupply_.add(_amount) <= cap);

    return super.mint(_to, _amount);
  }

}

// File: contracts/SintToken.sol

contract SintToken is BurnableToken, CappedToken {

    event TransfersUnlocked();
    event Timelock(address indexed beneficiary, uint256 releaseTime);

    string public constant name = "Sint Token";
    string public constant symbol = "SIN";
    uint8 public constant decimals = 18;

    mapping (address => uint256) private lockedUntil; // timestamps

    bool public lockedTransfers = true;

    function SintToken(
        uint256 _cap
    )
        public
        CappedToken(_cap.mul(1 ether))
    {
        //
    }

    modifier whenLockedTransfers() {
        require(lockedTransfers);
        _;
    }

    modifier whenUnlockedTransfers(address _sender) {
        require(!lockedTransfers);
        require(lockedUntil[_sender] < now, "Timelock"); // optional time lock
        _;
    }

    function unlockTransfers()
        onlyOwner
        whenLockedTransfers
        public
    {
        lockedTransfers = false;
        emit TransfersUnlocked();
    }

    function timelock(address _beneficiary, uint256 _releaseTime)
        onlyOwner
        whenLockedTransfers
        public
        returns (bool)
    {
        lockedUntil[_beneficiary] = _releaseTime;
        emit Timelock(_beneficiary, _releaseTime);
        return true;
    }

    function transfer(address _to, uint256 _value)
        whenUnlockedTransfers(msg.sender)
        public
        returns (bool)
    {
        return super.transfer(_to, _value);
    }

    function transferFrom(address _from, address _to, uint256 _value)
        whenUnlockedTransfers(_from)
        public
        returns (bool)
    {
        return super.transferFrom(_from, _to, _value);
    }

}

// File: zeppelin-solidity/contracts/crowdsale/Crowdsale.sol

/**
 * @title Crowdsale
 * @dev Crowdsale is a base contract for managing a token crowdsale,
 * allowing investors to purchase tokens with ether. This contract implements
 * such functionality in its most fundamental form and can be extended to provide additional
 * functionality and/or custom behavior.
 * The external interface represents the basic interface for purchasing tokens, and conform
 * the base architecture for crowdsales. They are *not* intended to be modified / overriden.
 * The internal interface conforms the extensible and modifiable surface of crowdsales. Override
 * the methods to add functionality. Consider using 'super' where appropiate to concatenate
 * behavior.
 */

contract Crowdsale {
  using SafeMath for uint256;

  // The token being sold
  ERC20 public token;

  // Address where funds are collected
  address public wallet;

  // How many token units a buyer gets per wei
  uint256 public rate;

  // Amount of wei raised
  uint256 public weiRaised;

  /**
   * 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);

  /**
   * @param _rate Number of token units a buyer gets per wei
   * @param _wallet Address where collected funds will be forwarded to
   * @param _token Address of the token being sold
   */
  function Crowdsale(uint256 _rate, address _wallet, ERC20 _token) public {
    require(_rate > 0);
    require(_wallet != address(0));
    require(_token != address(0));

    rate = _rate;
    wallet = _wallet;
    token = _token;
  }

  // -----------------------------------------
  // Crowdsale external interface
  // -----------------------------------------

  /**
   * @dev fallback function ***DO NOT OVERRIDE***
   */
  function () external payable {
    buyTokens(msg.sender);
  }

  /**
   * @dev low level token purchase ***DO NOT OVERRIDE***
   * @param _beneficiary Address performing the token purchase
   */
  function buyTokens(address _beneficiary) public payable {

    uint256 weiAmount = msg.value;
    _preValidatePurchase(_beneficiary, weiAmount);

    // calculate token amount to be created
    uint256 tokens = _getTokenAmount(weiAmount);

    // update state
    weiRaised = weiRaised.add(weiAmount);

    _processPurchase(_beneficiary, tokens);
    TokenPurchase(msg.sender, _beneficiary, weiAmount, tokens);

    _updatePurchasingState(_beneficiary, weiAmount);

    _forwardFunds();
    _postValidatePurchase(_beneficiary, weiAmount);
  }

  // -----------------------------------------
  // Internal interface (extensible)
  // -----------------------------------------

  /**
   * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met. Use super to concatenate validations.
   * @param _beneficiary Address performing the token purchase
   * @param _weiAmount Value in wei involved in the purchase
   */
  function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal {
    require(_beneficiary != address(0));
    require(_weiAmount != 0);
  }

  /**
   * @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid conditions are not met.
   * @param _beneficiary Address performing the token purchase
   * @param _weiAmount Value in wei involved in the purchase
   */
  function _postValidatePurchase(address _beneficiary, uint256 _weiAmount) internal {
    // optional override
  }

  /**
   * @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends its tokens.
   * @param _beneficiary Address performing the token purchase
   * @param _tokenAmount Number of tokens to be emitted
   */
  function _deliverTokens(address _beneficiary, uint256 _tokenAmount) internal {
    token.transfer(_beneficiary, _tokenAmount);
  }

  /**
   * @dev Executed when a purchase has been validated and is ready to be executed. Not necessarily emits/sends tokens.
   * @param _beneficiary Address receiving the tokens
   * @param _tokenAmount Number of tokens to be purchased
   */
  function _processPurchase(address _beneficiary, uint256 _tokenAmount) internal {
    _deliverTokens(_beneficiary, _tokenAmount);
  }

  /**
   * @dev Override for extensions that require an internal state to check for validity (current user contributions, etc.)
   * @param _beneficiary Address receiving the tokens
   * @param _weiAmount Value in wei involved in the purchase
   */
  function _updatePurchasingState(address _beneficiary, uint256 _weiAmount) internal {
    // optional override
  }

  /**
   * @dev Override to extend the way in which ether is converted to tokens.
   * @param _weiAmount Value in wei to be converted into tokens
   * @return Number of tokens that can be purchased with the specified _weiAmount
   */
  function _getTokenAmount(uint256 _weiAmount) internal view returns (uint256) {
    return _weiAmount.mul(rate);
  }

  /**
   * @dev Determines how ETH is stored/forwarded on purchases.
   */
  function _forwardFunds() internal {
    wallet.transfer(msg.value);
  }
}

// File: zeppelin-solidity/contracts/crowdsale/emission/MintedCrowdsale.sol

/**
 * @title MintedCrowdsale
 * @dev Extension of Crowdsale contract whose tokens are minted in each purchase.
 * Token ownership should be transferred to MintedCrowdsale for minting.
 */
contract MintedCrowdsale is Crowdsale {

  /**
   * @dev Overrides delivery by minting tokens upon purchase.
   * @param _beneficiary Token purchaser
   * @param _tokenAmount Number of tokens to be minted
   */
  function _deliverTokens(address _beneficiary, uint256 _tokenAmount) internal {
    require(MintableToken(token).mint(_beneficiary, _tokenAmount));
  }
}

// File: zeppelin-solidity/contracts/crowdsale/validation/CappedCrowdsale.sol

/**
 * @title CappedCrowdsale
 * @dev Crowdsale with a limit for total contributions.
 */
contract CappedCrowdsale is Crowdsale {
  using SafeMath for uint256;

  uint256 public cap;

  /**
   * @dev Constructor, takes maximum amount of wei accepted in the crowdsale.
   * @param _cap Max amount of wei to be contributed
   */
  function CappedCrowdsale(uint256 _cap) public {
    require(_cap > 0);
    cap = _cap;
  }

  /**
   * @dev Checks whether the cap has been reached.
   * @return Whether the cap was reached
   */
  function capReached() public view returns (bool) {
    return weiRaised >= cap;
  }

  /**
   * @dev Extend parent behavior requiring purchase to respect the funding cap.
   * @param _beneficiary Token purchaser
   * @param _weiAmount Amount of wei contributed
   */
  function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal {
    super._preValidatePurchase(_beneficiary, _weiAmount);
    require(weiRaised.add(_weiAmount) <= cap);
  }

}

// File: zeppelin-solidity/contracts/crowdsale/validation/TimedCrowdsale.sol

/**
 * @title TimedCrowdsale
 * @dev Crowdsale accepting contributions only within a time frame.
 */
contract TimedCrowdsale is Crowdsale {
  using SafeMath for uint256;

  uint256 public openingTime;
  uint256 public closingTime;

  /**
   * @dev Reverts if not in crowdsale time range.
   */
  modifier onlyWhileOpen {
    require(now >= openingTime && now <= closingTime);
    _;
  }

  /**
   * @dev Constructor, takes crowdsale opening and closing times.
   * @param _openingTime Crowdsale opening time
   * @param _closingTime Crowdsale closing time
   */
  function TimedCrowdsale(uint256 _openingTime, uint256 _closingTime) public {
    require(_openingTime >= now);
    require(_closingTime >= _openingTime);

    openingTime = _openingTime;
    closingTime = _closingTime;
  }

  /**
   * @dev Checks whether the period in which the crowdsale is open has already elapsed.
   * @return Whether crowdsale period has elapsed
   */
  function hasClosed() public view returns (bool) {
    return now > closingTime;
  }

  /**
   * @dev Extend parent behavior requiring to be within contributing period
   * @param _beneficiary Token purchaser
   * @param _weiAmount Amount of wei contributed
   */
  function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal onlyWhileOpen {
    super._preValidatePurchase(_beneficiary, _weiAmount);
  }

}

// File: contracts/SintCrowdsale.sol

contract SintCrowdsale is CappedCrowdsale, TimedCrowdsale, MintedCrowdsale, Ownable {

    uint256 public constant minAmount = 0.1 ether;

    // timestamps
    uint256[3] internal bonusEndDates = [
        1525687140, // 2018-05-07 23:59:59 CET
        1526291940, // 2018-05-14 23:59:59 CET
        1526896740 // 2018-05-21 23:59:59 CET
    ];

    uint8[3] internal bonusPercentages = [
        30,
        20,
        10
    ];

    address[8] internal advisorWallets = [
        0x542A625Ab5182Af9219B92A723e0B937a5edDCa5, // Bogdan Fiedur
        0xBd8DD5e35C9935fCB48B7575FbF1A25FC3BD0dCd, // Bas Geelen
        0xb5C51Ca28cbb7F07a8123275C3b51319588E767d, // Lin JC
        0x31F9961B4b42221680C3d86eA08761E4E121f231, // Jakub Garszynski
        0x8164876957be1bF660b81419421B16641af19dF9, // Tobias Schulz
        0x3e2eDBE3cC53f5105D8451D73846de47B38931f6, // Denis Farnosov
        0xcacc29637Ca90bC49F0aeD017C1eFCa50E0C2951, // Maciej Szafraniec
        0xc7F218965226391B89e7aEC7c10dafF384Eee7C7 // Shams Hassan
    ];

    address internal teamWallet = 0x78f1C69DcB99A5038e511e6f42F40ABd6bFA4d2a;

    function SintCrowdsale(
        uint256 _openingTime,
        uint256 _closingTime,
        uint256 _rate,
        address _wallet,
        SintToken _token,
        uint256 _cap
    )
        public
        Crowdsale(_rate, _wallet, _token)
        CappedCrowdsale(_cap.mul(1 ether))
        TimedCrowdsale(_openingTime, _closingTime)
    {
        require(bonusEndDates.length == bonusPercentages.length);
        require(advisorWallets.length > 0);
    }

    function _preValidatePurchase(address _beneficiary, uint256 _weiAmount)
        internal
    {
        require(_weiAmount >= minAmount);
        super._preValidatePurchase(_beneficiary, _weiAmount);
    }

    function _getCurrentBonus()
        internal
        view
        returns (uint8)
    {
        for (uint8 i = 0; i < bonusEndDates.length; i++)
        {
            if (bonusEndDates[i] > now)
            {
                return 100 + bonusPercentages[i];
            }
        }

        return 100;
    }

    function _getTokenAmount(uint256 _weiAmount)
        internal
        view
        returns (uint256)
    {
        uint8 currentBonus = _getCurrentBonus();
        return _weiAmount.mul(rate).mul(currentBonus).div(100);
    }

    function distributeTeamTokens()
        onlyOwner
        public
    {
        require(hasClosed());

        uint256 tokenCap = CappedToken(token).cap();

        // advisors
        // mint and split 3% of total token supply evenly between advisors
        uint256 advisorAllowance = tokenCap.mul(3).div(100).div(advisorWallets.length);
        for (uint8 i = 0; i < advisorWallets.length; i++)
        {
            require(MintableToken(token).mint(advisorWallets[i], advisorAllowance));
        }

        // founders and team
        // mint and lock for two years 6% of total supply
        uint256 teamAllowance = tokenCap.mul(6).div(100);
        require(MintableToken(token).mint(teamWallet, teamAllowance));
        require(SintToken(token).timelock(teamWallet, closingTime + 60 * 60 * 24 * 365 * 2));
    }

    function transferTokenOwnership(address newOwner)
        onlyOwner
        public
    {
        SintToken(token).transferOwnership(newOwner);
    }

}