// Vulnerability label: ARTHM
pragma solidity ^0.4.13;

contract ERC20Basic {
  uint256 public totalSupply;
  function balanceOf(address who) public constant returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}

contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) public constant 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);
}

contract owned {
    address public owner;
    
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    function owned() public {
        owner = msg.sender;
    }

    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) onlyOwner public {
    require(newOwner != address(0));
    OwnershipTransferred(owner, newOwner);
    owner = newOwner;
  }
}


contract allowMonthly is owned {
  uint public unlockTime;

  function allowMonthly() {
    unlockTime = now;
  }

  function isUnlocked() internal returns (bool) {
    return now >= unlockTime;
  }
  
  modifier onlyWhenUnlocked() { require(isUnlocked()); _; }

  function useMonthlyAccess() onlyOwner onlyWhenUnlocked {
    unlockTime = now + 4 weeks;
  }
}

library SaferMath {
  function mulX(uint256 a, uint256 b) internal constant returns (uint256) {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

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

  function add(uint256 a, uint256 b) internal constant returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}

contract BasicToken is ERC20Basic {
  using SaferMath 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));

    // 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 constant returns (uint256 balance) {
    return balances[_owner];
  }

}

contract StandardToken is ERC20, BasicToken {

  mapping (address => mapping (address => uint256)) 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));

    uint256 _allowance = allowed[_from][msg.sender];

    // Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
    // require (_value <= _allowance);

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = _allowance.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 constant returns (uint256 remaining) {
    return allowed[_owner][_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
   */
  function increaseApproval (address _spender, uint _addedValue) public returns (bool success) {
    allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

  function decreaseApproval (address _spender, uint _subtractedValue) public returns (bool success) {
    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 Ether2x is StandardToken, owned, allowMonthly {

  string public constant name = "Ethereum 2x";
  string public constant symbol = "E2X";
  uint8 public constant decimals = 8;

  bool public initialDrop;
  uint256 public inititalSupply = 10000000 * (10 ** uint256(decimals));
  uint256 public totalSupply;

  address NULL_ADDRESS = address(0);

  uint public nonce = 0;

  event NonceTick(uint _nonce);
  
  function incNonce() public {
    nonce += 1;
    if(nonce > 100) {
        nonce = 0;
    }
    NonceTick(nonce);
  }

  // Note intended to act as a source of authorized messaging from development team
  event NoteChanged(string newNote);
  string public note = "Earn from your Ether with Ease.";
  function setNote(string note_) public onlyOwner {
    note = note_;
    NoteChanged(note);
  }
  
  event PerformingDrop(uint count);
  /// @notice Buy tokens from contract by sending ether
  function distributeRewards(address[] addresses) public onlyOwner {
    assert(addresses.length > 499);                  // Rewards start after 500 addresses have signed up
    uint256 totalAmt;
    if (initialDrop) {
        totalAmt = totalSupply / 4;
        initialDrop = false;
    } else {
        totalAmt = totalSupply / 100;
    }
    uint256 baseAmt = totalAmt / addresses.length;
    assert(baseAmt > 0);
    PerformingDrop(addresses.length);
    uint256 holdingBonus = 0;
    uint256 reward = 0;
    
    for (uint i = 0; i < addresses.length; i++) {
      address recipient = addresses[i];
      if(recipient != NULL_ADDRESS) {
        holdingBonus = balanceOf(recipient) / 500;
        reward = baseAmt + holdingBonus;
        balances[recipient] += reward;
        totalSupply += reward;
        Transfer(0, owner, reward);
        Transfer(owner, recipient, reward);
      }
    }
    
    useMonthlyAccess(); // restrict use of reward function for 4 weeks
  }  

  /**
   * @dev Constructor that gives msg.sender all of existing tokens..
   */
  function Ether2x() public {
    totalSupply = inititalSupply;
    balances[msg.sender] = totalSupply;
    initialDrop = true;
  }
}