pragma solidity ^0.4.4;

contract ERC20Basic {
    uint256 public totalSupply;
    function balanceOf(address who) public constant returns (uint256 balance);
    function transfer(address to, uint256 value) public returns (bool success);
    event Transfer(address indexed from, address indexed to, uint256 value);
} 

contract ERC20 is ERC20Basic {
    function allowance(address owner, address spender) public constant returns (uint256 remaining);
    function transferFrom(address from, address to, uint256 value) public returns (bool success);
    function approve(address spender, uint256 value) public returns (bool success);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {
    
    function mul(uint256 a, uint256 b) internal constant returns (uint256) {
        uint256 c = a * b;
        assert(a == 0 || c / a == b);
        return c;
    }

    function div(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;
    }
  
}

/**
 * @title Basic token
 * @dev Basic version of StandardToken, with no allowances. 
 */
contract BasicToken is ERC20Basic {
    
    using SafeMath for uint256;

    mapping(address => uint256) public 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 success)  {
        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];
    }
 
}
 
/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 */
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 amout of tokens to be transfered
    */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success)  {
        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[_to] = balances[_to].add(_value);
        balances[_from] = balances[_from].sub(_value);
        allowed[_from][msg.sender] = _allowance.sub(_value);
        Transfer(_from, _to, _value);
        return true;
    }

    /**
    * @dev Aprove the passed address to spend the specified amount of tokens on behalf of msg.sender.
    * @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 success)  {

        require((_value == 0) || (allowed[msg.sender][_spender] == 0));

        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 specifing the amount of tokens still available for the spender.
    */
    function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }
 
}
 
/**
 * @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;

    /**
    * @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) onlyOwner  public {
        require(newOwner != address(0));      
        owner = newOwner;
    }
 
}
 
/**
 * @title Mintable token
 * @dev Simple ERC20 Token example, with mintable token creation
 */
 
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 recieve 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) public onlyOwner canMint 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() public onlyOwner returns (bool)  {
        mintingFinished = true;
        MintFinished();
        return true;
    }
  
}


// Token Contract
contract GWTToken is MintableToken {
    
    string public constant name = "Global Wind Token";
    
    string public constant symbol = "GWT";
    
    uint32 public constant decimals = 18; 

}