pragma solidity ^0.4.15;

/**
 * @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;
  }
}

contract IRntToken {
    uint256 public decimals = 18;

    uint256 public totalSupply = 1000000000 * (10 ** 18);

    string public name = "RNT Token";

    string public code = "RNT";


    function balanceOf() public constant returns (uint256 balance);

    function transfer(address _to, uint _value) public returns (bool success);

    function transferFrom(address _from, address _to, uint _value) public returns (bool success);
}

contract RntToken is IRntToken {
    using SafeMath for uint256;

    address public owner;

    /* The finalizer contract that allows unlift the transfer limits on this token */
    address public releaseAgent;

    /** A crowdsale contract can release us to the wild if ICO success. If false we are are in transfer lock up period.*/
    bool public released = false;

    /** Map of agents that are allowed to transfer tokens regardless of the lock down period.
    These are crowdsale contracts and possible the team multisig itself. */
    mapping (address => bool) public transferAgents;

    mapping (address => mapping (address => uint256)) public allowed;

    mapping (address => uint256) public balances;

    bool public paused = false;

    event Pause();

    event Unpause();

    event Approval(address indexed _owner, address indexed _spender, uint256 _value);

    event Transfer(address indexed _from, address indexed _to, uint _value);

    function RntToken() payable {
        require(msg.value == 0);
        owner = msg.sender;
        balances[msg.sender] = totalSupply;
    }

    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     */
    modifier whenNotPaused() {
        require(!paused);
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     */
    modifier whenPaused() {
        require(paused);
        _;
    }

    /**
     * Limit token transfer until the crowdsale is over.
     *
     */
    modifier canTransfer(address _sender) {
        require(released || transferAgents[_sender]);
        _;
    }

    /** The function can be called only before or after the tokens have been releasesd */
    modifier inReleaseState(bool releaseState) {
        require(releaseState == released);
        _;
    }

    /** The function can be called only by a whitelisted release agent. */
    modifier onlyReleaseAgent() {
        require(msg.sender == releaseAgent);
        _;
    }

    /**
     * Set the contract that can call release and make the token transferable.
     *
     * Design choice. Allow reset the release agent to fix fat finger mistakes.
     */
    function setReleaseAgent(address addr) onlyOwner inReleaseState(false) public {

        // We don't do interface check here as we might want to a normal wallet address to act as a release agent
        releaseAgent = addr;
    }

    /**
     * Owner can allow a particular address (a crowdsale contract) to transfer tokens despite the lock up period.
     */
    function setTransferAgent(address addr, bool state) onlyOwner inReleaseState(false) public {
        transferAgents[addr] = state;
    }

    /**
     * One way function to release the tokens to the wild.
     *
     * Can be called only from the release agent that is the final ICO contract. It is only called if the crowdsale has been success (first milestone reached).
     */
    function releaseTokenTransfer() public onlyReleaseAgent {
        released = true;
    }

    function transfer(address _to, uint _value) public canTransfer(msg.sender) whenNotPaused returns (bool success) {
        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;
    }

    function transferFrom(address _from, address _to, uint _value) public canTransfer(_from) whenNotPaused returns (bool success) {
        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];
    }

    /**
    * @dev Gets the balance of the sender address.
    * @return An uint256 representing the amount owned by the passed address.
    */
    function balanceOf() public constant returns (uint256 balance) {
        return balances[msg.sender];
    }


    /*PAUSABLE FUNCTIONALITY*/


    /**
     * @dev called by the owner to pause, triggers stopped state
     */
    function pause() onlyOwner whenNotPaused public {
        paused = true;
        Pause();
    }

    /**
     * @dev called by the owner to unpause, returns to normal state
     */
    function unpause() onlyOwner whenPaused public {
        paused = false;
        Unpause();
    }

    /*HAS NO ETHER FUNCTIONALITY*/
    /**
  * @dev Constructor that rejects incoming Ether
  * @dev The `payable` flag is added so we can access `msg.value` without compiler warning. If we
  * leave out payable, then Solidity will allow inheriting contracts to implement a payable
  * constructor. By doing it this way we prevent a payable constructor from working. Alternatively
  * we could use assembly to access msg.value.
  */

    /**
     * @dev Disallows direct send by settings a default function without the `payable` flag.
     */
    function() external {
    }
}