pragma solidity ^0.4.24;

/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, reverts on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    uint256 c = a * b;
    require(c / a == b);

    return c;
  }

  /**
  * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0); // Solidity only automatically asserts 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;
  }

  /**
  * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    uint256 c = a - b;

    return c;
  }

  /**
  * @dev Adds two numbers, reverts on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a);

    return c;
  }

  /**
  * @dev Divides two numbers and returns the remainder (unsigned integer modulo),
  * reverts when dividing by zero.
  */
  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0);
    return a % b;
  }
}



/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
interface IERC20 {
  function totalSupply() external view returns (uint256);

  function balanceOf(address who) external view returns (uint256);

  function allowance(address owner, address spender)
  external view returns (uint256);

  function transfer(address to, uint256 value) external returns (bool);

  function approve(address spender, uint256 value)
  external returns (bool);

  function transferFrom(address from, address to, uint256 value)
  external returns (bool);


  event Transfer(
    address indexed from,
    address indexed to,
    uint256 value
  );

  event TransferWithData(address indexed from, address indexed to, uint value, bytes data);

  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}



/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
 * Originally based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract ERC20 is IERC20 {
  using SafeMath for uint256;

  mapping (address => uint256) private _balances;

  mapping (address => mapping (address => uint256)) private _allowed;

  uint256 private _totalSupply;

  /**
  * @dev Total number of tokens in existence
  */
  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param owner The address to query 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];
  }

  /**
   * @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 Transfer the specified amount of tokens to the specified address.
   *      Invokes the `tokenFallback` function if the recipient is a contract.
   *      The token transfer fails if the recipient is a contract
   *      but does not implement the `tokenFallback` function
   *      or the fallback function to receive funds.
   *
   * @param _to    Receiver address.
   * @param _value Amount of tokens that will be transferred.
   * @param _data  Transaction metadata.
   */

  function transfer(address _to, uint _value, bytes _data) external returns (bool) {
    // Standard function transfer similar to ERC20 transfer with no _data .
    // Added due to backwards compatibility reasons .
    uint codeLength;

    require(_value / 1000000000000000000 >= 1);

    assembly {
    // Retrieve the size of the code on target address, this needs assembly .
      codeLength := extcodesize(_to)
    }

    _balances[msg.sender] = _balances[msg.sender].sub(_value);
    _balances[_to] = _balances[_to].add(_value);
    if (codeLength > 0) {
      ERC223ReceivingContract receiver = ERC223ReceivingContract(_to);

      receiver.tokenFallback(msg.sender, _value, _to);
    }
    emit TransferWithData(msg.sender, _to, _value, _data);
    emit Transfer(msg.sender, _to, _value);
    return true;
  }

  /**
   * @dev Transfer the specified amount of tokens to the specified address.
   *      This function works the same with the previous one
   *      but doesn't contain `_data` param.
   *      Added due to backwards compatibility reasons.
   *
   * @param _to    Receiver address.
   * @param _value Amount of tokens that will be transferred.
   */
  function transfer(address _to, uint _value) external returns (bool) {
    uint codeLength;
    bytes memory empty;

    require(_value / 1000000000000000000 >= 1);

    assembly {
    // Retrieve the size of the code on target address, this needs assembly .
      codeLength := extcodesize(_to)
    }

    _balances[msg.sender] = _balances[msg.sender].sub(_value);
    _balances[_to] = _balances[_to].add(_value);
    if (codeLength > 0) {
      ERC223ReceivingContract receiver = ERC223ReceivingContract(_to);
      receiver.tokenFallback(msg.sender, _value, address(this));
    }

    emit Transfer(msg.sender, _to, _value);
    emit TransferWithData(msg.sender, _to, _value, empty);
    return true;
  }


  /**
   * @dev Transfer the specified amount of tokens to the specified address.
   *      This function works the same with the previous one
   *      but doesn't contain `_data` param.
   *      Added due to backwards compatibility reasons.
   *
   * @param _to    Receiver address.
   * @param _value Amount of tokens that will be transferred.
   */
  function transferByCrowdSale(address _to, uint _value) external returns (bool) {
    bytes memory empty;

    require(_value / 1000000000000000000 >= 1);

    _balances[msg.sender] = _balances[msg.sender].sub(_value);
    _balances[_to] = _balances[_to].add(_value);

    emit Transfer(msg.sender, _to, _value);
    emit TransferWithData(msg.sender, _to, _value, empty);
    return true;
  }

  function _transferGasByOwner(address _from, address _to, uint256 _value) internal {
    _balances[_from] = _balances[_from].sub(_value);
    _balances[_to] = _balances[_to].add(_value);
    emit Transfer(_from, _to, _value);
  }


  /**
   * @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) {
    require(spender != address(0));

    _allowed[msg.sender][spender] = value;
    emit Approval(msg.sender, spender, value);
    return true;
  }

  /**
   * @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(value <= _allowed[from][msg.sender]);

    _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
    _transfer(from, to, value);
    return true;
  }

  /**
   * @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 increaseAllowance(
    address spender,
    uint256 addedValue
  )
  public
  returns (bool)
  {
    require(spender != address(0));

    _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 decreaseAllowance(
    address spender,
    uint256 subtractedValue
  )
  public
  returns (bool)
  {
    require(spender != address(0));

    _allowed[msg.sender][spender] = (
    _allowed[msg.sender][spender].sub(subtractedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  /**
  * @dev Transfer token for a specified addresses
  * @param from The address to transfer from.
  * @param to The address to transfer to.
  * @param value The amount to be transferred.
  */
  function _transfer(address from, address to, uint256 value) internal {
    require(value <= _balances[from]);
    require(to != address(0));

    _balances[from] = _balances[from].sub(value);
    _balances[to] = _balances[to].add(value);
    emit TransferWithData(from, to, value, '');
    emit Transfer(from, to, value);
  }

  /**
   * @dev Internal function that mints an amount of the token and assigns it to
   * an account. This encapsulates the modification of balances such that the
   * proper events are emitted.
   * @param account The account that will receive the created tokens.
   * @param value The amount that will be created.
   */
  function _mint(address account, uint256 value) internal {
    require(account != 0);
    _totalSupply = _totalSupply.add(value);
    _balances[account] = _balances[account].add(value);
    emit TransferWithData(address(0), account, value, '');
    emit Transfer(address(0), account, value);
  }

  /**
   * @dev Internal function that burns an amount of the token of a given
   * account.
   * @param account The account whose tokens will be burnt.
   * @param value The amount that will be burnt.
   */
  function _burn(address account, uint256 value) internal {
    require(account != 0);
    require(value <= _balances[account]);

    _totalSupply = _totalSupply.sub(value);
    _balances[account] = _balances[account].sub(value);
    emit TransferWithData(account, address(0), value, '');
    emit Transfer(account, address(0), value);
  }

  /**
   * @dev Internal function that burns an amount of the token of a given
   * account, deducting from the sender's allowance for said account. Uses the
   * internal burn function.
   * @param account The account whose tokens will be burnt.
   * @param value The amount that will be burnt.
   */
  function _burnFrom(address account, uint256 value) internal {
    require(value <= _allowed[account][msg.sender]);

    // Should https://github.com/OpenZeppelin/zeppelin-solidity/issues/707 be accepted,
    // this function needs to emit an event with the updated approval.
    _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(
      value);
    _burn(account, value);
  }
}


/**
 * @title Roles
 * @dev Library for managing addresses assigned to a Role.
 */
library Roles {
  struct Role {
    mapping (address => bool) bearer;
  }

  /**
   * @dev give an account access to this role
   */
  function add(Role storage role, address account) internal {
    require(account != address(0));
    role.bearer[account] = true;
  }

  /**
   * @dev remove an account's access to this role
   */
  function remove(Role storage role, address account) internal {
    require(account != address(0));
    role.bearer[account] = false;
  }

  /**
   * @dev check if an account has this role
   * @return bool
   */
  function has(Role storage role, address account)
  internal
  view
  returns (bool)
  {
    require(account != address(0));
    return role.bearer[account];
  }
}


contract MinterRole {
  using Roles for Roles.Role;

  event MinterAdded(address indexed account);
  event MinterRemoved(address indexed account);

  Roles.Role private minters;

  constructor() public {
    _addMinter(msg.sender);
  }

  modifier onlyMinter() {
    require(isMinter(msg.sender));
    _;
  }

  function isMinter(address account) public view returns (bool) {
    return minters.has(account);
  }

  function addMinter(address account) public onlyMinter {
    _addMinter(account);
  }

  function renounceMinter() public {
    _removeMinter(msg.sender);
  }

  function _addMinter(address account) internal {
    minters.add(account);
    emit MinterAdded(account);
  }

  function _removeMinter(address account) internal {
    minters.remove(account);
    emit MinterRemoved(account);
  }
}


/**
 * @title ERC20Mintable
 * @dev ERC20 minting logic
 */
contract ERC20Mintable is ERC20, MinterRole {
  /**
   * @dev Function to mint tokens
   * @param to The address that will receive the minted tokens.
   * @param value The amount of tokens to mint.
   * @return A boolean that indicates if the operation was successful.
   */
  function mint(
    address to,
    uint256 value
  )
  public
  onlyMinter
  returns (bool)
  {
    _mint(to, value);
    return true;
  }

  function transferGasByOwner(address _from, address _to, uint256 _value) public onlyMinter returns (bool) {
    super._transferGasByOwner(_from, _to, _value);
    return true;
  }
}


/**
 * @title SimpleToken
 * @dev Very simple ERC20 Token example, where all tokens are pre-assigned to the creator.
 * Note they can later distribute these tokens as they wish using `transfer` and other
 * `ERC20` functions.
 */
contract CryptoMusEstate is ERC20Mintable {

  string public constant name = "Mus#1";
  string public constant symbol = "MUS#1";
  uint8 public constant decimals = 18;

  uint256 public constant INITIAL_SUPPLY = 1000 * (10 ** uint256(decimals));

  /**
   * @dev Constructor that gives msg.sender all of existing tokens.
   */
  constructor() public {
    mint(msg.sender, INITIAL_SUPPLY);
  }

}


/**
 * @title SimpleToken
 * @dev Very simple ERC20 Token example, where all tokens are pre-assigned to the creator.
 * Note they can later distribute these tokens as they wish using `transfer` and other
 * `ERC20` functions.
 */
contract CryptoMusKRW is ERC20Mintable {

  string public constant name = "CryptoMus KRW Stable Token";
  string public constant symbol = "KRWMus";
  uint8 public constant decimals = 18;

  uint256 public constant INITIAL_SUPPLY = 10000000000 * (10 ** uint256(decimals));

  /**
   * @dev Constructor that gives msg.sender all of existing tokens.
   */
  constructor() public {
    mint(msg.sender, INITIAL_SUPPLY);
  }

}



/**
 * @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 private _owner;

  event OwnershipRenounced(address indexed previousOwner);
  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );

  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  constructor() public {
    _owner = msg.sender;
  }

  /**
   * @return the address of the owner.
   */
  function owner() public view returns (address) {
    return _owner;
  }

  /**
   * @dev Throws if called by any account other than the owner.
   */
  modifier onlyOwner() {
    require(isOwner());
    _;
  }

  /**
   * @return true if `msg.sender` is the owner of the contract.
   */
  function isOwner() public view returns (bool) {
    return msg.sender == _owner;
  }

  /**
   * @dev Allows the current owner to relinquish control of the contract.
   * @notice Renouncing to ownership will leave the contract without an owner.
   * It will not be possible to call the functions with the `onlyOwner`
   * modifier anymore.
   */
  function renounceOwnership() public onlyOwner {
    emit OwnershipRenounced(_owner);
    _owner = address(0);
  }

  /**
   * @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 {
    _transferOwnership(newOwner);
  }

  /**
   * @dev Transfers control of the contract to a newOwner.
   * @param newOwner The address to transfer ownership to.
   */
  function _transferOwnership(address newOwner) internal {
    require(newOwner != address(0));
    emit OwnershipTransferred(_owner, newOwner);
    _owner = newOwner;
  }
}

/**
 * @title Crowdsale
 * @dev Crowdsale is a base contract for managing a token crowdsale,
 * allowing investors to purchase tokens with ether. This contract implements
 * such functionality in its most fundamental form and can be extended to provide additional
 * functionality and/or custom behavior.
 * The external interface represents the basic interface for purchasing tokens, and conform
 * the base architecture for crowdsales. They are *not* intended to be modified / overridden.
 * The internal interface conforms the extensible and modifiable surface of crowdsales. Override
 * the methods to add functionality. Consider using 'super' where appropriate to concatenate
 * behavior.
 */
contract ERC223ReceivingContract is Ownable {
  using SafeMath for uint256;

  // The token being sold
  CryptoMusEstate private _token;
  // The token being sold
  CryptoMusKRW private _krwToken;

  // Address where funds are collected
  address private _wallet;
  address private _krwTokenAddress;

  // How many token units a buyer gets per wei.
  // The rate is the conversion between wei and the smallest and indivisible token unit.
  // So, if you are using a rate of 1 with a ERC20Detailed token with 3 decimals called TOK
  // 1 wei will give you 1 unit, or 0.001 TOK.
  uint256 private _rate;

  // Amount of wei raised
  uint256 private _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 TokensPurchased(
    address indexed purchaser,
    address indexed beneficiary,
    uint256 value,
    uint256 amount
  );

  /**
   * @param rate Number of token units a buyer gets per wei
   * @dev The rate is the conversion between wei and the smallest and indivisible
   * token unit. So, if you are using a rate of 1 with a ERC20Detailed token
   * with 3 decimals called TOK, 1 wei will give you 1 unit, or 0.001 TOK.
   * @param token Address of the token being sold
   */
  constructor(uint256 rate, CryptoMusEstate token, CryptoMusKRW krwToken) public {
    require(rate > 0);

    require(token != address(0));

    _rate = rate;
    _wallet = msg.sender;
    _token = token;
    _krwToken = krwToken;
    _krwTokenAddress = krwToken;
  }

  // -----------------------------------------
  // Crowdsale external interface
  // -----------------------------------------


  function tokenFallback(address _from, uint _value, address _to) public {

    if(_krwTokenAddress != _to) {
    } else {
      buyTokens(_from, _value);
    }
  }

  /**
   * @return the token being sold.
   */
  function token() public view returns (CryptoMusEstate) {
    return _token;
  }

  /**
   * @return the address where funds are collected.
   */
  function wallet() public view returns (address) {
    return _wallet;
  }

  /**
   * @return the number of token units a buyer gets per wei.
   */
  function rate() public view returns (uint256) {
    return _rate;
  }

  function setRate(uint256 setRate) public onlyOwner returns (uint256)
  {
    _rate = setRate;
    return _rate;
  }

  /**
   * @return the mount of wei raised.
   */
  function weiRaised() public view returns (uint256) {
    return _weiRaised;
  }

  /**
   * @dev low level token purchase ***DO NOT OVERRIDE***
   * @param beneficiary Address performing the token purchase
   */
  function buyTokens(address beneficiary, uint _value) public {

    uint256 weiAmount = _value;
    _preValidatePurchase(beneficiary, weiAmount);

    // calculate token amount to be created
    uint256 tokens = _getTokenAmount(weiAmount);

    // update state
    _weiRaised = _weiRaised.add(weiAmount);

    _processPurchase(beneficiary, tokens);
    emit TokensPurchased(
      msg.sender,
      beneficiary,
      weiAmount,
      tokens
    );

    _updatePurchasingState(beneficiary, weiAmount);

    _forwardFunds(_value);
    _postValidatePurchase(beneficiary, weiAmount);
  }

  // -----------------------------------------
  // Internal interface (extensible)
  // -----------------------------------------

  /**
   * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met. Use `super` in contracts that inherit from Crowdsale to extend their validations.
   * Example from CappedCrowdsale.sol's _preValidatePurchase method:
   *   super._preValidatePurchase(beneficiary, weiAmount);
   *   require(weiRaised().add(weiAmount) <= cap);
   * @param beneficiary Address performing the token purchase
   * @param weiAmount Value in wei involved in the purchase
   */
  function _preValidatePurchase(
    address beneficiary,
    uint256 weiAmount
  )
  internal
  {
    require(beneficiary != address(0));
    require(weiAmount != 0);
  }

  /**
   * @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid conditions are not met.
   * @param beneficiary Address performing the token purchase
   * @param weiAmount Value in wei involved in the purchase
   */
  function _postValidatePurchase(
    address beneficiary,
    uint256 weiAmount
  )
  internal
  {
    // optional override
  }

  /**
   * @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends its tokens.
   * @param beneficiary Address performing the token purchase
   * @param tokenAmount Number of tokens to be emitted
   */
  function _deliverTokens(
    address beneficiary,
    uint256 tokenAmount
  )
  internal
  {
    _token.transferByCrowdSale(beneficiary, tokenAmount);
  }

  /**
   * @dev Executed when a purchase has been validated and is ready to be executed. Not necessarily emits/sends tokens.
   * @param beneficiary Address receiving the tokens
   * @param tokenAmount Number of tokens to be purchased
   */
  function _processPurchase(
    address beneficiary,
    uint256 tokenAmount
  )
  internal
  {
    _deliverTokens(beneficiary, tokenAmount);
  }

  /**
   * @dev Override for extensions that require an internal state to check for validity (current user contributions, etc.)
   * @param beneficiary Address receiving the tokens
   * @param weiAmount Value in wei involved in the purchase
   */
  function _updatePurchasingState(
    address beneficiary,
    uint256 weiAmount
  )
  internal
  {
    // optional override
  }

  /**
   * @dev Override to extend the way in which ether is converted to tokens.
   * @param weiAmount Value in wei to be converted into tokens
   * @return Number of tokens that can be purchased with the specified _weiAmount
   */
  function _getTokenAmount(uint256 weiAmount)
  internal view returns (uint256)
  {
    return weiAmount.mul(_rate);
  }

  /**
   * @dev Determines how ETH is stored/forwarded on purchases.
   */
  function _forwardFunds(uint _value) internal {

    _krwToken.transferByCrowdSale(_wallet, _value);
  }
}