pragma solidity ^0.4.23;

/**
 * @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 c) {
    if (a == 0) {
      return 0;
    }
    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 a / b;
  }

  /**
  * @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 c) {
    c = a + b;
    assert(c >= a);
    return c;
  }
}

///////////////////////////////////////////
/**
 * @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);
}

/**
 * @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];
  }

}

/**
 * @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);
}

/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract OwnableToken {
  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 OwnableToken() 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;
  }

}

/**
 * @title Burnable Token
 * @dev Token that can be irreversibly burned (destroyed).
 */
contract BurnableToken is BasicToken, OwnableToken {

  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 onlyOwner {
    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);
  }
}

/**
 * @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;
  }

}

contract esToken is OwnableToken, BurnableToken, StandardToken {
	string public name;
	string public symbol;
	uint8 public decimals;

	bool public paused = true;
	mapping(address => bool) public whitelist;

	modifier whenNotPaused() {
		require(!paused || whitelist[msg.sender]);
		_;
	}

	constructor(string _name,string _symbol,uint8 _decimals, address holder, address buffer) public {
		name = _name;
		symbol = _symbol;
		decimals = _decimals;
		Transfer(address(0), holder, balances[holder] = totalSupply_ = uint256(10)**(9 + decimals));
		addToWhitelist(holder);
		addToWhitelist(buffer);
	}

	function unpause() public onlyOwner {
		paused = false;
	}

	function pause() public onlyOwner {
		paused = true;
	}

	function addToWhitelist(address addr) public onlyOwner {
		whitelist[addr] = true;
	}
    
	function removeFromWhitelist(address addr) public onlyOwner {
		whitelist[addr] = false;
	}

	function transfer(address to, uint256 value) public whenNotPaused returns (bool) {
		return super.transfer(to, value);
	}

	function transferFrom(address from, address to, uint256 value) public whenNotPaused returns (bool) {
		return super.transferFrom(from, to, value);
	}

}
///////////////////////////////////////////

//import "../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
   */
  constructor(uint256 _rate, address _wallet, ERC20 _token) public {
    require(_rate > 0);
    require(_wallet != 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);
    emit 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);
  }
}

//import "/zepp/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
   */
  constructor(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);
  }

}

//import "../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 {
    // solium-disable-next-line security/no-block-members
    require(block.timestamp >= openingTime && block.timestamp <= closingTime);
    _;
  }

  /**
   * @dev Constructor, takes crowdsale opening and closing times.
   * @param _openingTime Crowdsale opening time
   * @param _closingTime Crowdsale closing time
   */
  constructor(uint256 _openingTime, uint256 _closingTime) public {
    // solium-disable-next-line security/no-block-members
    //require(_openingTime >= block.timestamp);
    //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) {
    // solium-disable-next-line security/no-block-members
    return block.timestamp > 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);
  }

}

//import "../../../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 OwnershipRenounced(address indexed previousOwner);
  event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);


  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  constructor() 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;
  }

  /**
   * @dev Allows the current owner to relinquish control of the contract.
   */
  function renounceOwnership() public onlyOwner {
    emit OwnershipRenounced(owner);
    owner = address(0);
  }
}

//import "./FinalizableCrowdsale.sol";
/**
 * @title FinalizableCrowdsale
 * @dev Extension of Crowdsale where an owner can do extra work
 * after finishing.
 */
contract FinalizableCrowdsale is TimedCrowdsale, Ownable {
  using SafeMath for uint256;

  bool public isFinalized = false;

  event Finalized();

  /**
   * @dev Must be called after crowdsale ends, to do some extra finalization
   * work. Calls the contract's finalization function.
   */
  function finalize() onlyOwner public {
    require(!isFinalized);
    require(hasClosed());

    finalization();
    emit Finalized();

    isFinalized = true;
  }

  /**
   * @dev Can be overridden to add finalization logic. The overriding function
   * should call super.finalization() to ensure the chain of finalization is
   * executed entirely.
   */
  function finalization() internal {
  }

}

//import "./utils/RefundVault.sol";
/**
 * @title RefundVault
 * @dev This contract is used for storing funds while a crowdsale
 * is in progress. Supports refunding the money if crowdsale fails,
 * and forwarding it if crowdsale is successful.
 */
contract RefundVault is Ownable {
  using SafeMath for uint256;

  enum State { Active, Refunding, Closed }

  mapping (address => uint256) public deposited;
  address public wallet;
  State public state;

  event Closed();
  event RefundsEnabled();
  event Refunded(address indexed beneficiary, uint256 weiAmount);

  /**
   * @param _wallet Vault address
   */
  constructor(address _wallet) public {
    require(_wallet != address(0));
    wallet = _wallet;
    state = State.Active;
  }

  /**
   * @param investor Investor address
   */
  function deposit(address investor) onlyOwner public payable {
    require(state == State.Active);
    deposited[investor] = deposited[investor].add(msg.value);
  }

  function close() onlyOwner public {
    require(state == State.Active);
    state = State.Closed;
    emit Closed();
    wallet.transfer(address(this).balance);
  }

  function enableRefunds() onlyOwner public {
    require(state == State.Active);
    state = State.Refunding;
    emit RefundsEnabled();
  }

  /**
   * @param investor Investor address
   */
  function refund(address investor) public {
    require(state == State.Refunding);
    uint256 depositedValue = deposited[investor];
    deposited[investor] = 0;
    investor.transfer(depositedValue);
    emit Refunded(investor, depositedValue);
  }
}

//import "/zepp/crowdsale/distribution/RefundableCrowdsale.sol";
/**
 * @title RefundableCrowdsale
 * @dev Extension of Crowdsale contract that adds a funding goal, and
 * the possibility of users getting a refund if goal is not met.
 * Uses a RefundVault as the crowdsale's vault.
 */
contract RefundableCrowdsale is FinalizableCrowdsale {
  using SafeMath for uint256;

  // minimum amount of funds to be raised in weis
  uint256 public goal;

  // refund vault used to hold funds while crowdsale is running
  RefundVault public vault;

  /**
   * @dev Constructor, creates RefundVault.
   * @param _goal Funding goal
   */
  constructor(uint256 _goal) public {
    require(_goal > 0);
    vault = new RefundVault(wallet);
    goal = _goal;
  }

  /**
   * @dev Investors can claim refunds here if crowdsale is unsuccessful
   */
  function claimRefund() public {
    require(isFinalized);
    require(!goalReached());

    vault.refund(msg.sender);
  }

  /**
   * @dev Checks whether funding goal was reached.
   * @return Whether funding goal was reached
   */
  function goalReached() public view returns (bool) {
    return weiRaised >= goal;
  }

  /**
   * @dev vault finalization task, called when owner calls finalize()
   */
  function finalization() internal {
    if (goalReached()) {
      vault.close();
    } else {
      vault.enableRefunds();
    }

    super.finalization();
  }

  /**
   * @dev Overrides Crowdsale fund forwarding, sending funds to vault.
   */
  function _forwardFunds() internal {
    vault.deposit.value(msg.value)(msg.sender);
  }

}

/**
 * @title esCrowdsale
 * @dev This is an example of a fully fledged crowdsale.
 * The way to add new features to a base crowdsale is by multiple inheritance.
 * In this example we are providing following extensions:
 * CappedCrowdsale - sets a max boundary for raised funds
 * RefundableCrowdsale - set a min goal to be reached and returns funds if it's not met
 *
 * After adding multiple features it's good practice to run integration tests
 * to ensure that subcontracts works together as intended.
 */
contract esCrowdsale is CappedCrowdsale, RefundableCrowdsale {

  constructor(
    uint256 _openingTime,
    uint256 _closingTime,
    uint256 _rate,
    address _wallet,
    uint256 _cap,
    ERC20 _token,
    uint256 _goal
  )
    public
    Crowdsale(_rate, _wallet, _token)
    CappedCrowdsale(_cap)
    TimedCrowdsale(_openingTime, _closingTime)
    RefundableCrowdsale(_goal)
  {
    //As goal needs to be met for a successful crowdsale
    //the value needs to less or equal than a cap which is limit for accepted funds
    require(_goal <= _cap);
  }
}