// File: contracts/Token/Sender.sol

pragma solidity ^0.5.0;


/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Sender {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor() internal {}

    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts-ethereum-package/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.5.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP. Does not include
 * the optional functions; to access them see {ERC20Detailed}.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: 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
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: @openzeppelin/upgrades/contracts/Initializable.sol

pragma solidity >=0.4.24 <0.6.0;


/**
 * @title Initializable
 *
 * @dev Helper contract to support initializer functions. To use it, replace
 * the constructor with a function that has the `initializer` modifier.
 * WARNING: Unlike constructors, initializer functions must be manually
 * invoked. This applies both to deploying an Initializable contract, as well
 * as extending an Initializable contract via inheritance.
 * WARNING: When used with inheritance, manual care must be taken to not invoke
 * a parent initializer twice, or ensure that all initializers are idempotent,
 * because this is not dealt with automatically as with constructors.
 */
contract Initializable {

  /**
   * @dev Indicates that the contract has been initialized.
   */
  bool private initialized;

  /**
   * @dev Indicates that the contract is in the process of being initialized.
   */
  bool private initializing;

  /**
   * @dev Modifier to use in the initializer function of a contract.
   */
  modifier initializer() {
    require(initializing || isConstructor() || !initialized, "Contract instance has already been initialized");

    bool isTopLevelCall = !initializing;
    if (isTopLevelCall) {
      initializing = true;
      initialized = true;
    }

    _;

    if (isTopLevelCall) {
      initializing = false;
    }
  }

  /// @dev Returns true if and only if the function is running in the constructor
  function isConstructor() private view returns (bool) {
    // extcodesize checks the size of the code stored in an address, and
    // address returns the current address. Since the code is still not
    // deployed when running a constructor, any checks on its code size will
    // yield zero, making it an effective way to detect if a contract is
    // under construction or not.
    uint256 cs;
    assembly { cs := extcodesize(address) }
    return cs == 0;
  }

  // Reserved storage space to allow for layout changes in the future.
  uint256[50] private ______gap;
}

// File: @openzeppelin/contracts-ethereum-package/contracts/GSN/Context.sol

pragma solidity ^0.5.0;


/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Context is Initializable {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts-ethereum-package/contracts/ownership/Ownable.sol

pragma solidity ^0.5.0;



/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be aplied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Initializable, Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    function initialize(address sender) public initializer {
        _owner = sender;
        emit OwnershipTransferred(address(0), _owner);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _owner;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * > Note: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }

    uint256[50] private ______gap;
}

// File: contracts/utils/DateTimeLibrary.sol

pragma solidity ^0.5.0;

// ----------------------------------------------------------------------------
// BokkyPooBah's DateTime Library v1.01
//
// A gas-efficient Solidity date and time library
//
// https://github.com/bokkypoobah/BokkyPooBahsDateTimeLibrary
//
// Tested date range 1970/01/01 to 2345/12/31
//
// Conventions:
// Unit      | Range         | Notes
// :-------- |:-------------:|:-----
// timestamp | >= 0          | Unix timestamp, number of seconds since 1970/01/01 00:00:00 UTC
// year      | 1970 ... 2345 |
// month     | 1 ... 12      |
// day       | 1 ... 31      |
// hour      | 0 ... 23      |
// minute    | 0 ... 59      |
// second    | 0 ... 59      |
// dayOfWeek | 1 ... 7       | 1 = Monday, ..., 7 = Sunday
//
//
// Enjoy. (c) BokkyPooBah / Bok Consulting Pty Ltd 2018-2019. The MIT Licence.
// ----------------------------------------------------------------------------

library DateTimeLibrary {
    uint256 constant SECONDS_PER_DAY = 24 * 60 * 60;
    uint256 constant SECONDS_PER_HOUR = 60 * 60;
    uint256 constant SECONDS_PER_MINUTE = 60;
    int256 constant OFFSET19700101 = 2440588;

    uint256 constant DOW_MON = 1;
    uint256 constant DOW_TUE = 2;
    uint256 constant DOW_WED = 3;
    uint256 constant DOW_THU = 4;
    uint256 constant DOW_FRI = 5;
    uint256 constant DOW_SAT = 6;
    uint256 constant DOW_SUN = 7;

    // ------------------------------------------------------------------------
    // Calculate the number of days from 1970/01/01 to year/month/day using
    // the date conversion algorithm from
    //   http://aa.usno.navy.mil/faq/docs/JD_Formula.php
    // and subtracting the offset 2440588 so that 1970/01/01 is day 0
    //
    // days = day
    //      - 32075
    //      + 1461 * (year + 4800 + (month - 14) / 12) / 4
    //      + 367 * (month - 2 - (month - 14) / 12 * 12) / 12
    //      - 3 * ((year + 4900 + (month - 14) / 12) / 100) / 4
    //      - offset
    // ------------------------------------------------------------------------
    function _daysFromDate(uint256 year, uint256 month, uint256 day)
        internal
        pure
        returns (uint256 _days)
    {
        require(year >= 1970);
        int256 _year = int256(year);
        int256 _month = int256(month);
        int256 _day = int256(day);

        int256 __days = _day -
            32075 +
            (1461 * (_year + 4800 + (_month - 14) / 12)) /
            4 +
            (367 * (_month - 2 - ((_month - 14) / 12) * 12)) /
            12 -
            (3 * ((_year + 4900 + (_month - 14) / 12) / 100)) /
            4 -
            OFFSET19700101;

        _days = uint256(__days);
    }

    // ------------------------------------------------------------------------
    // Calculate year/month/day from the number of days since 1970/01/01 using
    // the date conversion algorithm from
    //   http://aa.usno.navy.mil/faq/docs/JD_Formula.php
    // and adding the offset 2440588 so that 1970/01/01 is day 0
    //
    // int L = days + 68569 + offset
    // int N = 4 * L / 146097
    // L = L - (146097 * N + 3) / 4
    // year = 4000 * (L + 1) / 1461001
    // L = L - 1461 * year / 4 + 31
    // month = 80 * L / 2447
    // dd = L - 2447 * month / 80
    // L = month / 11
    // month = month + 2 - 12 * L
    // year = 100 * (N - 49) + year + L
    // ------------------------------------------------------------------------
    function _daysToDate(uint256 _days)
        internal
        pure
        returns (uint256 year, uint256 month, uint256 day)
    {
        int256 __days = int256(_days);

        int256 L = __days + 68569 + OFFSET19700101;
        int256 N = (4 * L) / 146097;
        L = L - (146097 * N + 3) / 4;
        int256 _year = (4000 * (L + 1)) / 1461001;
        L = L - (1461 * _year) / 4 + 31;
        int256 _month = (80 * L) / 2447;
        int256 _day = L - (2447 * _month) / 80;
        L = _month / 11;
        _month = _month + 2 - 12 * L;
        _year = 100 * (N - 49) + _year + L;

        year = uint256(_year);
        month = uint256(_month);
        day = uint256(_day);
    }

    function daysFromDate(uint256 year, uint256 month, uint256 day)
        internal
        pure
        returns (uint256 daysSinceDate)
    {
        daysSinceDate = _daysFromDate(year, month, day);
    }
    function timestampFromDate(uint256 year, uint256 month, uint256 day)
        internal
        pure
        returns (uint256 timestamp)
    {
        timestamp = _daysFromDate(year, month, day) * SECONDS_PER_DAY;
    }
    function timestampFromDateTime(
        uint256 year,
        uint256 month,
        uint256 day,
        uint256 hour,
        uint256 minute,
        uint256 second
    ) internal pure returns (uint256 timestamp) {
        timestamp =
            _daysFromDate(year, month, day) *
            SECONDS_PER_DAY +
            hour *
            SECONDS_PER_HOUR +
            minute *
            SECONDS_PER_MINUTE +
            second;
    }
    function timestampToDate(uint256 timestamp)
        internal
        pure
        returns (uint256 year, uint256 month, uint256 day)
    {
        (year, month, day) = _daysToDate(timestamp / SECONDS_PER_DAY);
    }
    function timestampToDateTime(uint256 timestamp)
        internal
        pure
        returns (
            uint256 year,
            uint256 month,
            uint256 day,
            uint256 hour,
            uint256 minute,
            uint256 second
        )
    {
        (year, month, day) = _daysToDate(timestamp / SECONDS_PER_DAY);
        uint256 secs = timestamp % SECONDS_PER_DAY;
        hour = secs / SECONDS_PER_HOUR;
        secs = secs % SECONDS_PER_HOUR;
        minute = secs / SECONDS_PER_MINUTE;
        second = secs % SECONDS_PER_MINUTE;
    }

    function isValidDate(uint256 year, uint256 month, uint256 day)
        internal
        pure
        returns (bool valid)
    {
        if (year >= 1970 && month > 0 && month <= 12) {
            uint256 daysInMonth = _getDaysInMonth(year, month);
            if (day > 0 && day <= daysInMonth) {
                valid = true;
            }
        }
    }
    function isValidDateTime(
        uint256 year,
        uint256 month,
        uint256 day,
        uint256 hour,
        uint256 minute,
        uint256 second
    ) internal pure returns (bool valid) {
        if (isValidDate(year, month, day)) {
            if (hour < 24 && minute < 60 && second < 60) {
                valid = true;
            }
        }
    }
    function isLeapYear(uint256 timestamp)
        internal
        pure
        returns (bool leapYear)
    {
        (uint256 year, , ) = _daysToDate(timestamp / SECONDS_PER_DAY);
        leapYear = _isLeapYear(year);
    }
    function _isLeapYear(uint256 year) internal pure returns (bool leapYear) {
        leapYear = ((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0);
    }
    function isWeekDay(uint256 timestamp) internal pure returns (bool weekDay) {
        weekDay = getDayOfWeek(timestamp) <= DOW_FRI;
    }
    function isWeekEnd(uint256 timestamp) internal pure returns (bool weekEnd) {
        weekEnd = getDayOfWeek(timestamp) >= DOW_SAT;
    }
    function getDaysInMonth(uint256 timestamp)
        internal
        pure
        returns (uint256 daysInMonth)
    {
        (uint256 year, uint256 month, ) = _daysToDate(
            timestamp / SECONDS_PER_DAY
        );
        daysInMonth = _getDaysInMonth(year, month);
    }
    function _getDaysInMonth(uint256 year, uint256 month)
        internal
        pure
        returns (uint256 daysInMonth)
    {
        if (
            month == 1 ||
            month == 3 ||
            month == 5 ||
            month == 7 ||
            month == 8 ||
            month == 10 ||
            month == 12
        ) {
            daysInMonth = 31;
        } else if (month != 2) {
            daysInMonth = 30;
        } else {
            daysInMonth = _isLeapYear(year) ? 29 : 28;
        }
    }
    // 1 = Monday, 7 = Sunday
    function getDayOfWeek(uint256 timestamp)
        internal
        pure
        returns (uint256 dayOfWeek)
    {
        uint256 _days = timestamp / SECONDS_PER_DAY;
        dayOfWeek = ((_days + 3) % 7) + 1;
    }

    function getYear(uint256 timestamp) internal pure returns (uint256 year) {
        (year, , ) = _daysToDate(timestamp / SECONDS_PER_DAY);
    }
    function getMonth(uint256 timestamp) internal pure returns (uint256 month) {
        (, month, ) = _daysToDate(timestamp / SECONDS_PER_DAY);
    }
    function getDay(uint256 timestamp) internal pure returns (uint256 day) {
        (, , day) = _daysToDate(timestamp / SECONDS_PER_DAY);
    }
    function getHour(uint256 timestamp) internal pure returns (uint256 hour) {
        uint256 secs = timestamp % SECONDS_PER_DAY;
        hour = secs / SECONDS_PER_HOUR;
    }
    function getMinute(uint256 timestamp)
        internal
        pure
        returns (uint256 minute)
    {
        uint256 secs = timestamp % SECONDS_PER_HOUR;
        minute = secs / SECONDS_PER_MINUTE;
    }
    function getSecond(uint256 timestamp)
        internal
        pure
        returns (uint256 second)
    {
        second = timestamp % SECONDS_PER_MINUTE;
    }

    function addYears(uint256 timestamp, uint256 _years)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        (uint256 year, uint256 month, uint256 day) = _daysToDate(
            timestamp / SECONDS_PER_DAY
        );
        year += _years;
        uint256 daysInMonth = _getDaysInMonth(year, month);
        if (day > daysInMonth) {
            day = daysInMonth;
        }
        newTimestamp =
            _daysFromDate(year, month, day) *
            SECONDS_PER_DAY +
            (timestamp % SECONDS_PER_DAY);
        require(newTimestamp >= timestamp);
    }
    function addMonths(uint256 timestamp, uint256 _months)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        (uint256 year, uint256 month, uint256 day) = _daysToDate(
            timestamp / SECONDS_PER_DAY
        );
        month += _months;
        year += (month - 1) / 12;
        month = ((month - 1) % 12) + 1;
        uint256 daysInMonth = _getDaysInMonth(year, month);
        if (day > daysInMonth) {
            day = daysInMonth;
        }
        newTimestamp =
            _daysFromDate(year, month, day) *
            SECONDS_PER_DAY +
            (timestamp % SECONDS_PER_DAY);
        require(newTimestamp >= timestamp);
    }
    function addDays(uint256 timestamp, uint256 _days)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        newTimestamp = timestamp + _days * SECONDS_PER_DAY;
        require(newTimestamp >= timestamp);
    }
    function addHours(uint256 timestamp, uint256 _hours)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        newTimestamp = timestamp + _hours * SECONDS_PER_HOUR;
        require(newTimestamp >= timestamp);
    }
    function addMinutes(uint256 timestamp, uint256 _minutes)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        newTimestamp = timestamp + _minutes * SECONDS_PER_MINUTE;
        require(newTimestamp >= timestamp);
    }
    function addSeconds(uint256 timestamp, uint256 _seconds)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        newTimestamp = timestamp + _seconds;
        require(newTimestamp >= timestamp);
    }

    function subYears(uint256 timestamp, uint256 _years)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        (uint256 year, uint256 month, uint256 day) = _daysToDate(
            timestamp / SECONDS_PER_DAY
        );
        year -= _years;
        uint256 daysInMonth = _getDaysInMonth(year, month);
        if (day > daysInMonth) {
            day = daysInMonth;
        }
        newTimestamp =
            _daysFromDate(year, month, day) *
            SECONDS_PER_DAY +
            (timestamp % SECONDS_PER_DAY);
        require(newTimestamp <= timestamp);
    }
    function subMonths(uint256 timestamp, uint256 _months)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        (uint256 year, uint256 month, uint256 day) = _daysToDate(
            timestamp / SECONDS_PER_DAY
        );
        uint256 yearMonth = year * 12 + (month - 1) - _months;
        year = yearMonth / 12;
        month = (yearMonth % 12) + 1;
        uint256 daysInMonth = _getDaysInMonth(year, month);
        if (day > daysInMonth) {
            day = daysInMonth;
        }
        newTimestamp =
            _daysFromDate(year, month, day) *
            SECONDS_PER_DAY +
            (timestamp % SECONDS_PER_DAY);
        require(newTimestamp <= timestamp);
    }
    function subDays(uint256 timestamp, uint256 _days)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        newTimestamp = timestamp - _days * SECONDS_PER_DAY;
        require(newTimestamp <= timestamp);
    }
    function subHours(uint256 timestamp, uint256 _hours)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        newTimestamp = timestamp - _hours * SECONDS_PER_HOUR;
        require(newTimestamp <= timestamp);
    }
    function subMinutes(uint256 timestamp, uint256 _minutes)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        newTimestamp = timestamp - _minutes * SECONDS_PER_MINUTE;
        require(newTimestamp <= timestamp);
    }
    function subSeconds(uint256 timestamp, uint256 _seconds)
        internal
        pure
        returns (uint256 newTimestamp)
    {
        newTimestamp = timestamp - _seconds;
        require(newTimestamp <= timestamp);
    }

    function diffYears(uint256 fromTimestamp, uint256 toTimestamp)
        internal
        pure
        returns (uint256 _years)
    {
        require(fromTimestamp <= toTimestamp);
        (uint256 fromYear, , ) = _daysToDate(fromTimestamp / SECONDS_PER_DAY);
        (uint256 toYear, , ) = _daysToDate(toTimestamp / SECONDS_PER_DAY);
        _years = toYear - fromYear;
    }
    function diffMonths(uint256 fromTimestamp, uint256 toTimestamp)
        internal
        pure
        returns (uint256 _months)
    {
        require(fromTimestamp <= toTimestamp);
        (uint256 fromYear, uint256 fromMonth, ) = _daysToDate(
            fromTimestamp / SECONDS_PER_DAY
        );
        (uint256 toYear, uint256 toMonth, ) = _daysToDate(
            toTimestamp / SECONDS_PER_DAY
        );
        _months = toYear * 12 + toMonth - fromYear * 12 - fromMonth;
    }
    function diffDays(uint256 fromTimestamp, uint256 toTimestamp)
        internal
        pure
        returns (uint256 _days)
    {
        require(fromTimestamp <= toTimestamp);
        _days = (toTimestamp - fromTimestamp) / SECONDS_PER_DAY;
    }
    function diffHours(uint256 fromTimestamp, uint256 toTimestamp)
        internal
        pure
        returns (uint256 _hours)
    {
        require(fromTimestamp <= toTimestamp);
        _hours = (toTimestamp - fromTimestamp) / SECONDS_PER_HOUR;
    }
    function diffMinutes(uint256 fromTimestamp, uint256 toTimestamp)
        internal
        pure
        returns (uint256 _minutes)
    {
        require(fromTimestamp <= toTimestamp);
        _minutes = (toTimestamp - fromTimestamp) / SECONDS_PER_MINUTE;
    }
    function diffSeconds(uint256 fromTimestamp, uint256 toTimestamp)
        internal
        pure
        returns (uint256 _seconds)
    {
        require(fromTimestamp <= toTimestamp);
        _seconds = toTimestamp - fromTimestamp;
    }
}

// File: contracts/utils/Math.sol

/// Math.sol -- mixin for inline numerical wizardry

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.5.0;


library DSMath {

    // --- Unsigned Math ----
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, "ds-math-add-overflow");
    }
    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, "ds-math-sub-underflow");
    }
    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, "ds-math-mul-overflow");
    }


    function min(uint x, uint y) internal pure returns (uint z) {
        return x <= y ? x : y;
    }
    function max(uint x, uint y) internal pure returns (uint z) {
        return x >= y ? x : y;
    }
    function imin(int x, int y) internal pure returns (int z) {
        return x <= y ? x : y;
    }
    function imax(int x, int y) internal pure returns (int z) {
        return x >= y ? x : y;
    }

    // --- Precise Math ---

    uint public constant WAD = 10 ** 18;
    uint public constant RAY = 10 ** 27;

    function wmul(uint x, uint y) internal pure returns (uint z) {
        z = add(mul(x, y), WAD / 2) / WAD;
    }
    function rmul(uint x, uint y) internal pure returns (uint z) {
        z = add(mul(x, y), RAY / 2) / RAY;
    }
    function wdiv(uint x, uint y) internal pure returns (uint z) {
        z = add(mul(x, WAD), y / 2) / y;
    }
    function rdiv(uint x, uint y) internal pure returns (uint z) {
        z = add(mul(x, RAY), y / 2) / y;
    }

    function ray(uint _wad) internal pure returns (uint) {
        return mul(_wad, uint(10 ** 9));
    }

    // This famous algorithm is called "exponentiation by squaring"
    // and calculates x^n with x as fixed-point and n as regular unsigned.
    //
    // It's O(log n), instead of O(n) for naive repeated multiplication.
    //
    // These facts are why it works:
    //
    //  If n is even, then x^n = (x^2)^(n/2).
    //  If n is odd,  then x^n = x * x^(n-1),
    //   and applying the equation for even x gives
    //    x^n = x * (x^2)^((n-1) / 2).
    //
    //  Also, EVM division is flooring and
    //    floor[(n-1) / 2] = floor[n / 2].
    //
    function rpow(uint x, uint n) internal pure returns (uint z) {
        z = n % 2 != 0 ? x : RAY;

        for (n /= 2; n != 0; n /= 2) {
            x = rmul(x, x);

            if (n % 2 != 0) {
                z = rmul(z, x);
            }
        }
    }
}

// File: contracts/PersistentStorage.sol

pragma solidity ^0.5.0;





contract PersistentStorage is Ownable {
    address public tokenSwapManager;
    address public bridge;

    bool public isPaused;
    bool public isShutdown;

    struct Accounting {
        uint256 price;
        uint256 cashPositionPerTokenUnit;
        uint256 balancePerTokenUnit;
        uint256 lendingFee;
    }

    struct Order {
        string orderType;
        uint256 tokensGiven;
        uint256 tokensRecieved;
        uint256 avgBlendedFee;
    }

    uint256 public lastActivityDay;
    uint256 public minRebalanceAmount;
    uint256 public managementFee;
    uint256 public minimumMintingFee;
    uint256 public minimumTrade;

    uint8 public balancePrecision;

    mapping(uint256 => Accounting[]) private accounting;

    uint256[] public mintingFeeBracket;
    mapping(uint256 => uint256) public mintingFee;

    Order[] public allOrders;
    mapping(address => Order[]) public orderByUser;
    mapping(address => uint256) public delayedRedemptionsByUser;

    event AccountingValuesSet(uint256 today);
    event RebalanceValuesSet(uint256 newMinRebalanceAmount);
    event ManagementFeeValuesSet(uint256 newManagementFee);

    function initialize(
        address ownerAddress,
        uint256 _managementFee,
        uint256 _minRebalanceAmount,
        uint8 _balancePrecision,
        uint256 _lastMintingFee,
        uint256 _minimumMintingFee,
        uint256 _minimumTrade
    ) public initializer {
        initialize(ownerAddress);
        managementFee = _managementFee;
        minRebalanceAmount = _minRebalanceAmount;
        mintingFee[~uint256(0)] = _lastMintingFee;
        balancePrecision = _balancePrecision;
        minimumMintingFee = _minimumMintingFee;
        minimumTrade = _minimumTrade;
    }

    function setTokenSwapManager(address _tokenSwapManager) public onlyOwner {
        require(_tokenSwapManager != address(0), "adddress must not be empty");
        tokenSwapManager = _tokenSwapManager;
    }

    function setBridge(address _bridge) public onlyOwner {
        require(_bridge != address(0), "adddress must not be empty");
        bridge = _bridge;
    }

    function setIsPaused(bool _isPaused) public onlyOwner {
        isPaused = _isPaused;
    }

    function shutdown() public onlyOwner {
        isShutdown = true;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwnerOrTokenSwap() {
        require(
            isOwner() || _msgSender() == tokenSwapManager,
            "caller is not the owner or token swap manager"
        );
        _;
    }

    modifier onlyOwnerOrBridge() {
        require(
            isOwner() || _msgSender() == bridge,
            "caller is not the owner or bridge"
        );
        _;
    }

    function setDelayedRedemptionsByUser(
        uint256 amountToRedeem,
        address whitelistedAddress
    ) public onlyOwnerOrTokenSwap {
        delayedRedemptionsByUser[whitelistedAddress] = amountToRedeem;
    }

    /*
     * Saves order in mapping (address => Order[]) orderByUser
     * overwrite == false, append to Order[]
     * overwrite == true, overwrite element at orderIndex
     */

    function setOrderByUser(
        address whitelistedAddress,
        string memory orderType,
        uint256 tokensGiven,
        uint256 tokensRecieved,
        uint256 avgBlendedFee,
        uint256 orderIndex,
        bool overwrite
    ) public onlyOwnerOrTokenSwap() {
        Order memory newOrder = Order(
            orderType,
            tokensGiven,
            tokensRecieved,
            avgBlendedFee
        );

        if (!overwrite) {
            orderByUser[whitelistedAddress].push(newOrder);
            setOrder(
                orderType,
                tokensGiven,
                tokensRecieved,
                avgBlendedFee,
                orderIndex,
                overwrite
            );
        } else {
            orderByUser[whitelistedAddress][orderIndex] = newOrder;
        }
    }

    /*
     * Gets Order[] For User Address
     * Return order at Index in Order[]
     */

    function getOrderByUser(address whitelistedAddress, uint256 orderIndex)
        public
        view
        returns (
            string memory orderType,
            uint256 tokensGiven,
            uint256 tokensRecieved,
            uint256 avgBlendedFee
        )
    {

            Order storage orderAtIndex
         = orderByUser[whitelistedAddress][orderIndex];
        return (
            orderAtIndex.orderType,
            orderAtIndex.tokensGiven,
            orderAtIndex.tokensRecieved,
            orderAtIndex.avgBlendedFee
        );
    }

    /*
     * Save order to allOrders array
     * overwrite == false, append to allOrders array
     * overwrite == true, overwrite element at orderIndex
     */
    function setOrder(
        string memory orderType,
        uint256 tokensGiven,
        uint256 tokensRecieved,
        uint256 avgBlendedFee,
        uint256 orderIndex,
        bool overwrite
    ) public onlyOwnerOrTokenSwap() {
        Order memory newOrder = Order(
            orderType,
            tokensGiven,
            tokensRecieved,
            avgBlendedFee
        );

        if (!overwrite) {
            allOrders.push(newOrder);
        } else {
            allOrders[orderIndex] = newOrder;
        }
    }

    /*
     * Get Order
     */
    function getOrder(uint256 index)
        public
        view
        returns (
            string memory orderType,
            uint256 tokensGiven,
            uint256 tokensRecieved,
            uint256 avgBlendedFee
        )
    {
        Order storage orderAtIndex = allOrders[index];
        return (
            orderAtIndex.orderType,
            orderAtIndex.tokensGiven,
            orderAtIndex.tokensRecieved,
            orderAtIndex.avgBlendedFee
        );
    }

    // @dev Get accounting values for a specific day
    // @param date format as 20200123 for 23th of January 2020
    function getAccounting(uint256 date)
        public
        view
        returns (uint256, uint256, uint256, uint256)
    {
        return (
            accounting[date][accounting[date].length - 1].price,
            accounting[date][accounting[date].length - 1]
                .cashPositionPerTokenUnit,
            accounting[date][accounting[date].length - 1].balancePerTokenUnit,
            accounting[date][accounting[date].length - 1].lendingFee
        );
    }

    // @dev Set accounting values for the day
    function setAccounting(
        uint256 _price,
        uint256 _cashPositionPerTokenUnit,
        uint256 _balancePerTokenUnit,
        uint256 _lendingFee
    ) external onlyOwnerOrTokenSwap() {
        (uint256 year, uint256 month, uint256 day) = DateTimeLibrary
            .timestampToDate(block.timestamp);
        uint256 today = year * 10000 + month * 100 + day;
        accounting[today].push(
            Accounting(
                _price,
                _cashPositionPerTokenUnit,
                _balancePerTokenUnit,
                _lendingFee
            )
        );
        lastActivityDay = today;
        emit AccountingValuesSet(today);
    }

    // @dev Set accounting values for the day
    function setAccountingForLastActivityDay(
        uint256 _price,
        uint256 _cashPositionPerTokenUnit,
        uint256 _balancePerTokenUnit,
        uint256 _lendingFee
    ) external onlyOwnerOrTokenSwap() {
        accounting[lastActivityDay].push(
            Accounting(
                _price,
                _cashPositionPerTokenUnit,
                _balancePerTokenUnit,
                _lendingFee
            )
        );
        emit AccountingValuesSet(lastActivityDay);
    }

    // @dev Set last rebalance information
    function setMinRebalanceAmount(uint256 _minRebalanceAmount)
        external
        onlyOwner
    {
        minRebalanceAmount = _minRebalanceAmount;

        emit RebalanceValuesSet(minRebalanceAmount);
    }

    // @dev Set last rebalance information
    function setManagementFee(uint256 _managementFee) external onlyOwner {
        managementFee = _managementFee;
        emit ManagementFeeValuesSet(managementFee);
    }

    // @dev Returns price
    function getPrice() public view returns (uint256 price) {
        return
            accounting[lastActivityDay][accounting[lastActivityDay].length - 1]
                .price;
    }

    // @dev Returns cash position amount
    function getCashPositionPerTokenUnit()
        public
        view
        returns (uint256 amount)
    {
        return
            accounting[lastActivityDay][accounting[lastActivityDay].length - 1]
                .cashPositionPerTokenUnit;
    }

    // @dev Returns borrowed crypto amount
    function getBalancePerTokenUnit() public view returns (uint256 amount) {
        return
            accounting[lastActivityDay][accounting[lastActivityDay].length - 1]
                .balancePerTokenUnit;
    }

    // @dev Returns lending fee
    function getLendingFee() public view returns (uint256 lendingRate) {
        return
            accounting[lastActivityDay][accounting[lastActivityDay].length - 1]
                .lendingFee;
    }

    // @dev Sets last minting fee
    function setLastMintingFee(uint256 _mintingFee) public onlyOwner {
        mintingFee[~uint256(0)] = _mintingFee;
    }

    // @dev Adds minting fee
    function addMintingFeeBracket(uint256 _mintingFeeLimit, uint256 _mintingFee)
        public
        onlyOwner
    {
        require(
            mintingFeeBracket.length == 0 ||
                _mintingFeeLimit >
                mintingFeeBracket[mintingFeeBracket.length - 1],
            "New minting fee bracket needs to be bigger then last one"
        );
        mintingFeeBracket.push(_mintingFeeLimit);
        mintingFee[_mintingFeeLimit] = _mintingFee;
    }

    // @dev Deletes last minting fee
    function deleteLastMintingFeeBracket() public onlyOwner {
        delete mintingFee[mintingFeeBracket[mintingFeeBracket.length - 1]];
        mintingFeeBracket.length--;
    }

    // @dev Changes minting fee
    function changeMintingLimit(
        uint256 _position,
        uint256 _mintingFeeLimit,
        uint256 _mintingFee
    ) public onlyOwner {
        require(
            _mintingFeeLimit > mintingFeeBracket[mintingFeeBracket.length - 1],
            "New minting fee bracket needs to be bigger then last one"
        );
        if (_position != 0) {
            require(
                _mintingFeeLimit > mintingFeeBracket[_position - 1],
                "New minting fee bracket needs to be bigger then last one"
            );
        }
        if (_position < mintingFeeBracket.length - 1) {
            require(
                _mintingFeeLimit < mintingFeeBracket[_position + 1],
                "New minting fee bracket needs to be smaller then next one"
            );
        }
        mintingFeeBracket[_position] = _mintingFeeLimit;
        mintingFee[_mintingFeeLimit] = _mintingFee;
    }

    function getMintingFee(uint256 cash) public view returns (uint256) {
        // Define Start + End Index
        uint256 startIndex = 0;
        uint256 endIndex = mintingFeeBracket.length - 1;
        uint256 middleIndex = endIndex / 2;

        if (cash <= mintingFeeBracket[middleIndex]) {
            endIndex = middleIndex;
        } else {
            startIndex = middleIndex + 1;
        }

        for (uint256 i = startIndex; i <= endIndex; i++) {
            if (cash <= mintingFeeBracket[i]) {
                return mintingFee[mintingFeeBracket[i]];
            }
        }
        return mintingFee[~uint256(0)];
    }

    // @dev Sets last balance precision
    function setLastPrecision(uint8 _balancePrecision) public onlyOwner {
        balancePrecision = _balancePrecision;
    }

    // @dev Sets minimum minting fee
    function setMinimumMintingFee(uint256 _minimumMintingFee) public onlyOwner {
        minimumMintingFee = _minimumMintingFee;
    }

    // @dev Sets minimum trade value
    function setMinimumTrade(uint256 _minimumTrade) public onlyOwner {
        minimumTrade = _minimumTrade;
    }
}

// File: contracts/Token/ERC20Detailed.sol

pragma solidity ^0.5.0;






/**
 * @dev Optional functions from the ERC20 standard.
 */
contract ERC20Detailed is IERC20, Initializable, Ownable {
    string private _name;
    string private _symbol;
    uint8 private _decimals;
    PersistentStorage public _persistenStorage;

    /**
     * @dev Sets the values for `name`, `symbol`, and `decimals`. All three of
     * these values are immutable: they can only be set once during
     * construction.
     */
    function initialize(
        string memory name,
        string memory symbol,
        uint8 decimals,
        address persistenStorage,
        address ownerAddress
    ) public initializer {
        initialize(ownerAddress);
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
        _persistenStorage = PersistentStorage(persistenStorage);
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

// File: @openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol

pragma solidity ^0.5.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot 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-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: contracts/Token/ERC20.sol

pragma solidity ^0.5.0;





/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20Mintable}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Sender, ERC20Detailed {
    using SafeMath for uint256;

    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender)
        public
        view
        returns (uint256)
    {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20};
     *
     * Requirements:
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for `sender`'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount)
        public
        returns (bool)
    {
        _transfer(sender, recipient, amount);
        _approve(
            sender,
            _msgSender(),
            _allowances[sender][_msgSender()].sub(
                amount,
                "ERC20: transfer amount exceeds allowance"
            )
        );
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue)
        public
        returns (bool)
    {
        _approve(
            _msgSender(),
            spender,
            _allowances[_msgSender()][spender].add(addedValue)
        );
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue)
        public
        returns (bool)
    {
        _approve(
            _msgSender(),
            spender,
            _allowances[_msgSender()][spender].sub(
                subtractedValue,
                "ERC20: decreased allowance below zero"
            )
        );
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount)
        internal
    {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender].sub(
            amount,
            "ERC20: transfer amount exceeds balance"
        );
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: burn from the zero address");

        _balances[account] = _balances[account].sub(
            amount,
            "ERC20: burn amount exceeds balance"
        );
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
     *
     * This is internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`.`amount` is then deducted
     * from the caller's allowance.
     *
     * See {_burn} and {_approve}.
     */
    function _burnFrom(address account, uint256 amount) internal {
        _burn(account, amount);
        _approve(
            account,
            _msgSender(),
            _allowances[account][_msgSender()].sub(
                amount,
                "ERC20: burn amount exceeds allowance"
            )
        );
    }
}

// File: contracts/Token/InverseToken.sol

pragma solidity ^0.5.0;



contract InverseToken is ERC20 {
    function mintTokens(address destinationAddress, uint256 amountToMint)
        public
        onlyOwnerOrTokenSwap()
        returns (bool)
    {
        // Mint Tokens on Successful Creation order
        _mint(destinationAddress, amountToMint);
        return true;
    }

    function burnTokens(address fromAddress, uint256 amountToBurn)
        public
        onlyOwnerOrTokenSwap()
        returns (bool)
    {
        // Burn Tokens on Successful Redemption Order
        _burn(fromAddress, amountToBurn);
        return true;
    }

    modifier onlyOwnerOrTokenSwap() {
        require(
            isOwner() || _msgSender() == _persistenStorage.tokenSwapManager(),
            "caller is not the owner or token swap manager"
        );
        _;
    }

    uint256[50] private ______gap;
}