pragma solidity ^0.4.23;

/**
 * @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;
  }
}

contract Ownable {
  address public owner;

  event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   */
  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.
   */
  function transferOwnership(address newOwner) public onlyOwner {
    require(newOwner != address(0));
    OwnershipTransferred(owner, newOwner);
    owner = newOwner;
  }

}

contract Claimable is Ownable {
  address public pendingOwner;

  /**
   * @dev Modifier throws if called by any account other than the pendingOwner.
   */
  modifier onlyPendingOwner() {
    require(msg.sender == pendingOwner);
    _;
  }

  /**
   * @dev Allows the current owner to set the pendingOwner address.
   */
  function transferOwnership(address newOwner) public onlyOwner{
    pendingOwner = newOwner;
  }

  /**
   * @dev Allows the pendingOwner address to finalize the transfer.
   */
  function claimOwnership() onlyPendingOwner public {
    OwnershipTransferred(owner, pendingOwner);
    owner = pendingOwner;
    pendingOwner = address(0);
  }
}

contract Pausable is Ownable {
  event Pause();
  event Unpause();

  bool public paused = false;


  /**
   * @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);
    _;
  }

  /**
   * @dev called by the owner to pause, triggers stopped state
   */
  function pause() onlyOwner whenNotPaused public {
    paused = true;
    emit Pause();
  }

  /**
   * @dev called by the owner to unpause, returns to normal state
   */
  function unpause() onlyOwner whenPaused public {
    paused = false;
    emit Unpause();
  }
}

/**
 * @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);
}

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
  );
}

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];
  }

}


contract BurnableToken is BasicToken {

  event Burn(address indexed burner, uint256 value);

  /**
   * @dev Burns a specific amount of tokens.
   * @param _value The amount of token to be burned.
   */
  function burn(uint256 _value) public {
    _burn(msg.sender, _value);
  }

  function _burn(address _who, uint256 _value) internal {
    require(_value <= balances[_who]);
    // no need to require value <= totalSupply, since that would imply the
    // sender's balance is greater than the totalSupply, which *should* be an assertion failure

    balances[_who] = balances[_who].sub(_value);
    totalSupply_ = totalSupply_.sub(_value);
    emit Burn(_who, _value);
    emit Transfer(_who, address(0), _value);
  }
}

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 PausableToken is StandardToken, Pausable {

  function transfer(address _to, uint256 _value) public whenNotPaused returns (bool) {
    return super.transfer(_to, _value);
  }

  function transferFrom(address _from, address _to, uint256 _value) public whenNotPaused returns (bool) {
    return super.transferFrom(_from, _to, _value);
  }

  function approve(address _spender, uint256 _value) public whenNotPaused returns (bool) {
    return super.approve(_spender, _value);
  }

  function increaseApproval(address _spender, uint _addedValue) public whenNotPaused returns (bool success) {
    return super.increaseApproval(_spender, _addedValue);
  }

  function decreaseApproval(address _spender, uint _subtractedValue) public whenNotPaused returns (bool success)
  {
    return super.decreaseApproval(_spender, _subtractedValue);
  }
}

contract ComissionList is Claimable {
  using SafeMath for uint256;

  struct Transfer {
    uint256 stat;
    uint256 perc;
  }

  mapping (string => Transfer) refillPaySystemInfo;
  mapping (string => Transfer) widthrawPaySystemInfo;

  Transfer transferInfo;

  event RefillCommisionIsChanged(string _paySystem, uint256 stat, uint256 perc);
  event WidthrawCommisionIsChanged(string _paySystem, uint256 stat, uint256 perc);
  event TransferCommisionIsChanged(uint256 stat, uint256 perc);

  // установить информацию по комиссии для пополняемой платёжной системы
  function setRefillFor(string _paySystem, uint256 _stat, uint256 _perc) public onlyOwner returns (uint256) {
    refillPaySystemInfo[_paySystem].stat = _stat;
    refillPaySystemInfo[_paySystem].perc = _perc;

    RefillCommisionIsChanged(_paySystem, _stat, _perc);
  }

  // установить информацию по комиссии для снимаеомй платёжной системы
  function setWidthrawFor(string _paySystem,uint256 _stat, uint256 _perc) public onlyOwner returns (uint256) {
    widthrawPaySystemInfo[_paySystem].stat = _stat;
    widthrawPaySystemInfo[_paySystem].perc = _perc;

    WidthrawCommisionIsChanged(_paySystem, _stat, _perc);
  }

  // установить информацию по комиссии для перевода
  function setTransfer(uint256 _stat, uint256 _perc) public onlyOwner returns (uint256) {
    transferInfo.stat = _stat;
    transferInfo.perc = _perc;

    TransferCommisionIsChanged(_stat, _perc);
  }

  // взять процент по комиссии для пополняемой платёжной системы
  function getRefillStatFor(string _paySystem) public view returns (uint256) {
    return refillPaySystemInfo[_paySystem].perc;
  }

  // взять фикс по комиссии для пополняемой платёжной системы
  function getRefillPercFor(string _paySystem) public view returns (uint256) {
    return refillPaySystemInfo[_paySystem].stat;
  }

  // взять процент по комиссии для снимаемой платёжной системы
  function getWidthrawStatFor(string _paySystem) public view returns (uint256) {
    return widthrawPaySystemInfo[_paySystem].perc;
  }

  // взять фикс по комиссии для снимаемой платёжной системы
  function getWidthrawPercFor(string _paySystem) public view returns (uint256) {
    return widthrawPaySystemInfo[_paySystem].stat;
  }

  // взять процент по комиссии для перевода
  function getTransferPerc() public view returns (uint256) {
    return transferInfo.perc;
  }
  
  // взять фикс по комиссии для перевода
  function getTransferStat() public view returns (uint256) {
    return transferInfo.stat;
  }

  // рассчитать комиссию со снятия для платёжной системы и суммы
  function calcWidthraw(string _paySystem, uint256 _value) public view returns(uint256) {
    uint256 _totalComission;
    _totalComission = widthrawPaySystemInfo[_paySystem].stat + (_value / 100 ) * widthrawPaySystemInfo[_paySystem].perc;

    return _totalComission;
  }

  // рассчитать комиссию с пополнения для платёжной системы и суммы
  function calcRefill(string _paySystem, uint256 _value) public view returns(uint256) {
    uint256 _totalComission;
    _totalComission = refillPaySystemInfo[_paySystem].stat + (_value / 100 ) * refillPaySystemInfo[_paySystem].perc;

    return _totalComission;
  }

  // рассчитать комиссию с перевода для платёжной системы и суммы
  function calcTransfer(uint256 _value) public view returns(uint256) {
    uint256 _totalComission;
    _totalComission = transferInfo.stat + (_value / 100 ) * transferInfo.perc;

    return _totalComission;
  }
}

contract EvaCurrency is PausableToken, BurnableToken {
  string public name = "EvaUSD";
  string public symbol = "EUSD";

  ComissionList public comissionList;

  uint8 public constant decimals = 3;

  mapping(address => uint) lastUsedNonce;

  address public staker;

  event Mint(address indexed to, uint256 amount);

  function EvaCurrency(string _name, string _symbol) public {
    name = _name;
    symbol = _symbol;
    staker = msg.sender;
  }

  function changeName(string _name, string _symbol) onlyOwner public {
      name = _name;
      symbol = _symbol;
  }

  function setComissionList(ComissionList _comissionList) onlyOwner public {
    comissionList = _comissionList;
  }

  modifier onlyStaker() {
    require(msg.sender == staker);
    _;
  }

  // Перевод между кошельками по VRS
  function transferOnBehalf(address _to, uint _amount, uint _nonce, uint8 _v, bytes32 _r, bytes32 _s) onlyStaker public returns (bool success) {
    uint256 fee;
    uint256 resultAmount;
    bytes32 hash = keccak256(_to, _amount, _nonce, address(this));
    address sender = ecrecover(hash, _v, _r, _s);

    require(lastUsedNonce[sender] < _nonce);
    require(_amount <= balances[sender]);

    fee = comissionList.calcTransfer(_amount);
    resultAmount = _amount.sub(fee);

    balances[sender] = balances[sender].sub(_amount);
    balances[_to] = balances[_to].add(resultAmount);
    balances[staker] = balances[staker].add(fee);
    lastUsedNonce[sender] = _nonce;
    
    return true;
  }

  function withdrawOnBehalf(uint _amount, string _paySystem, uint _nonce, uint8 _v, bytes32 _r, bytes32 _s) onlyStaker public returns (bool success) {
    uint256 fee;
    uint256 resultAmount;
    bytes32 hash = keccak256(address(0), _amount, _nonce, address(this));
    address sender = ecrecover(hash, _v, _r, _s);

    require(lastUsedNonce[sender] < _nonce);
    require(_amount <= balances[sender]);

    fee = comissionList.calcWidthraw(_paySystem, _amount);
    resultAmount = _amount.sub(fee);

    balances[sender] = balances[sender].sub(_amount);
    balances[staker] = balances[staker].add(fee);
    totalSupply_.sub(resultAmount);

    Burn(sender, resultAmount);
    return true;
  }

  // Пополнение баланса пользователя, так-же отправляет комиссию для staker
  // _to - адрес пополняемого кошелька, _amount - сумма, _paySystem - платёжная система
  function refill(address _to, uint256 _amount, string _paySystem) onlyStaker public returns (bool success) {
      uint256 fee;
      uint256 resultAmount;

      fee = comissionList.calcRefill(_paySystem, _amount);
      resultAmount = _amount.sub(fee);

      balances[_to] = balances[staker].add(resultAmount);
      balances[staker] = balances[staker].add(fee);
      totalSupply_.add(_amount);

      Mint(_to, resultAmount);
      return true;
  }

  function changeStaker(address _staker) onlyOwner public returns (bool success) {
    staker = _staker;
  }
  
  function getNullAddress() public view returns (address) {
    return address(0);
  }
}