pragma solidity ^0.4.21;


/**
 * @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]);

		balances[msg.sender] = balances[msg.sender].sub(_value);
		balances[_to] = balances[_to].add(_value);
		emit 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) {
		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 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);
		emit 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;
		emit 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);
		emit 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);
		}
		emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
		return true;
	}

}

contract NomToken is StandardToken {
	event Mint(address indexed to, uint256 amount);

	address public owner;
	
	string public constant name = "NOM Token"; 
	string public constant symbol = "NOM";
	uint8 public constant decimals = 18;	
	
	uint256 public constant totalTokens = 5650000000 * (10 ** uint256(decimals));
	
	uint256 public initialIssueMinting = totalTokens.mul(60).div(100);	//60% of tokens
	uint public constant initialIssueMintingDate = 1524873600;			//28.04.2018 UTC
	bool public initialIssueMinted = false;
		
	uint256 public firstStageMinting = totalTokens.mul(10).div(100);	//10% of tokens
	uint public constant firstStageMintingDate = 1532736000;			//28.07.2018 UTC
	bool public firstStageMinted = false;
		
	uint256 public secondStageMinting = totalTokens.mul(10).div(100);	//10% of tokens
	uint public constant secondStageMintingDate = 1540684800;			//28.10.2018 UTC
	bool public secondStageMinted = false;
	
	uint256 public thirdStageMinting = totalTokens.mul(10).div(100);	//10% of tokens
	uint public constant thirdStageMintingDate = 1548633600;			//28.01.2019 UTC
	bool public thirdStageMinted = false;
	
	uint256 public fourthStageMinting = totalTokens.mul(10).div(100);	//10% of tokens
	uint public constant fourthStageMintingDate = 1556409600;			//28.04.2019 UTC
	bool public fourthStageMinted = false;
		
	function NomToken() public {
		owner = msg.sender;
	}
	
	 /**
	 * @dev Function to mint tokens
	 * @return A boolean that indicates if the operation was successful.
	 */
	function mint() public returns (bool) {
		require(msg.sender == owner);
		
		uint256 tokensToMint = 0;
		if (now > initialIssueMintingDate && !initialIssueMinted) {
				tokensToMint = tokensToMint.add(initialIssueMinting);
				initialIssueMinted = true;
		}
		if (now > firstStageMintingDate && !firstStageMinted) {
				tokensToMint = tokensToMint.add(firstStageMinting);
				firstStageMinted = true;
		}
		if (now > secondStageMintingDate && !secondStageMinted) {
				tokensToMint = tokensToMint.add(secondStageMinting);
				secondStageMinted = true;
		}
		if (now > thirdStageMintingDate && !thirdStageMinted) {
				tokensToMint = tokensToMint.add(thirdStageMinting);
				thirdStageMinted = true;
		}
		if (now > fourthStageMintingDate && !fourthStageMinted) {
				tokensToMint = tokensToMint.add(fourthStageMinting);
				fourthStageMinted = true;
		}
		require(tokensToMint > 0);
		uint256 newTotalSupply = totalSupply_.add(tokensToMint);
		require(newTotalSupply <= totalTokens);
		
		totalSupply_ = totalSupply_.add(tokensToMint);
		balances[owner] = balances[owner].add(tokensToMint);
		emit Mint(owner, tokensToMint);
		emit Transfer(0x0, owner, tokensToMint);
		return true;
	}
}