pragma solidity ^0.4.18;

/**
 * @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));
    OwnershipTransferred(owner, newOwner);
    owner = newOwner;
  }
}


/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/179
 */
contract ERC20Basic {
  uint256 public totalSupply;
  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 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 Basic token
 * @dev Basic version of StandardToken, with no allowances.
 */
contract BasicToken is ERC20Basic {
  using SafeMath for uint256;
  mapping(address => uint256) balances;
  /**
  * @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 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;
  }
}


/**
 * @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);
    _;
  }  
  //NMY Jan 2018: added constructor
  string public constant symbol = "SIZ";
  string public  constant name = "SIZ Token";
  uint8 public constant decimals = 18;
  uint256 public constant INITIAL_SUPPLY = 1000000000 * (10 ** uint256(decimals));
  function MintableToken(address _wallet) public {
     totalSupply = INITIAL_SUPPLY;
     balances[_wallet] = INITIAL_SUPPLY;
     Mint(_wallet, INITIAL_SUPPLY);
  }

  /**
   * @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;
  }
}


/**
 * @title Crowdsale
 * @dev Crowdsale is a base contract for managing a token crowdsale.
 * Crowdsales have a start and end timestamps, where investors can make
 * token purchases and the crowdsale will assign them tokens based
 * on a token per ETH rate. Funds collected are forwarded to a wallet
 * as they arrive.
 */
contract Crowdsale {
  using SafeMath for uint256;
  // The token being sold
  MintableToken public token;
  // start and end timestamps where investments are allowed (both inclusive)
  uint256 public startTime = now + 86400*31 seconds;
  uint256 public endTime =  startTime + 86400*365 seconds;
  
  //uint256 public startTime = now + 120 seconds;
  //uint256 public endTime =  startTime + 3600 seconds;
  // address where funds are collected
  address public wallet = 0xc96c60469E38Fb5f725A7e1a134394a91aC9488f;
  // how many minimum-token units a buyer gets per wei 
  // (ie for 18 decimals token: how many tokens per ether)
  uint256 public rate =  100000;
  // amount of raised money in wei
  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);
  function Crowdsale() public {
    require(startTime >= now);
    require(endTime >= startTime);
    require(rate > 0);
    require(wallet != address(0));
    // NMY Jan 2018: added _wallet parameter
    token = createTokenContract(wallet);
  }
  // creates the token to be sold.
  // override this method to have crowdsale of a specific mintable token.
  // NMY Jan 2018: added _wallet parameter
  function createTokenContract(address _wallet) internal returns (MintableToken) {
    return new MintableToken(_wallet);
  }
  // fallback function can be used to buy tokens
  function () external payable {
    buyTokens(msg.sender);
  }
  // low level token purchase function
  function buyTokens(address beneficiary) public payable {
    require(beneficiary != address(0));
    require(validPurchase());
    uint256 weiAmount = msg.value;
    // calculate token amount to be created
    // uint256 tokens = weiAmount.mul(rate);
    uint256 rateScaled = rate.mul
            (2 ** uint256(11*(now-startTime)/(endTime-startTime+1))); 
    uint256 tokens = weiAmount.mul(rateScaled);
    
    // update state
    weiRaised = weiRaised.add(weiAmount);
    token.mint(beneficiary, tokens);
    TokenPurchase(msg.sender, beneficiary, weiAmount, tokens);
    forwardFunds();
  }
  // send ether to the fund collection wallet
  // override to create custom fund forwarding mechanisms
  function forwardFunds() internal {
    wallet.transfer(msg.value);
  }
  // @return true if the transaction can buy tokens
  function validPurchase() internal view returns (bool) {
    bool withinPeriod = now >= startTime && now <= endTime;
    bool nonZeroPurchase = msg.value != 0;
    return withinPeriod && nonZeroPurchase;
  }
  // @return true if crowdsale event has ended
  function hasEnded() public view returns (bool) {
    return now > endTime;
  }
}


/**
 * @title FinalizableCrowdsale
 * @dev Extension of Crowdsale where an owner can do extra work
 * after finishing.
 */
contract FinalizableCrowdsale is Crowdsale, 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(hasEnded());
    finalization();
    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 {
      //NMY
      //isFinalized = false;
  }
}


/**
 * @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);
  function RefundVault(address _wallet) public {
    require(_wallet != address(0));
    wallet = _wallet;
    state = State.Active;
  }
/**/
  function deposit(address investor) onlyOwner public payable {
    require(state == State.Active);
    deposited[investor] = deposited[investor].add(msg.value);
    //deposited[investor] = SafeMath.add(deposited[investor], msg.value);
  }
  function close() onlyOwner public {
    require(state == State.Active);
    state = State.Closed;
    Closed();
    wallet.transfer(this.balance);
  }
  function enableRefunds() onlyOwner public {
    require(state == State.Active);
    state = State.Refunding;
    RefundsEnabled();
  }
  function refund(address investor) public {
    require(state == State.Refunding);
    uint256 depositedValue = deposited[investor];
    deposited[investor] = 0;
    investor.transfer(depositedValue);
    Refunded(investor, depositedValue);
  }
  /**/
  
}



/**
 * @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 = 5000 * (10 ** 18);
  // refund vault used to hold funds while crowdsale is running
  RefundVault public vault;
  function RefundableCrowdsale() public {
    require(goal > 0);
    vault = new RefundVault(wallet);
  }
  // We're overriding the fund forwarding from Crowdsale.
  // In addition to sending the funds, we want to call
  // the RefundVault deposit function
  // NMY Jan 2018: forwardFunds after the goal is reached
  /**/
  function forwardFunds() internal {
    if (goalReached()) {
        super.forwardFunds();
        if(vault.balance >= 1) vault.close();
    } else {
        vault.deposit.value(msg.value)(msg.sender);
    }
  }
  
  // if crowdsale is unsuccessful, investors can claim refunds here
  function claimRefund() public {
    require(isFinalized);
    require(!goalReached());
    vault.refund(msg.sender);
  }
  
  // vault finalization task, called when owner calls finalize()
  function finalization() internal {
    if (goalReached()) {
        if(vault.balance >= 1)
           vault.close();
    } else {
        vault.enableRefunds();
    }
    super.finalization();
  }
  
  function goalReached() public view returns (bool) {
    return weiRaised >= goal;
  }
  /**/
}