Staking 01032302

// SPDX-License-Identifier: BSD-4-Clause
/*
 * ABDK Math 64.64 Smart Contract Library.  Copyright © 2019 by ABDK Consulting.
 * Author: Mikhail Vladimirov <mikhail.vladimirov@gmail.com>
 */
pragma solidity ^0.8.0;

/**
 * Smart contract library of mathematical functions operating with signed
 * 64.64-bit fixed point numbers.  Signed 64.64-bit fixed point number is
 * basically a simple fraction whose numerator is signed 128-bit integer and
 * denominator is 2^64.  As long as denominator is always the same, there is no
 * need to store it, thus in Solidity signed 64.64-bit fixed point numbers are
 * represented by int128 type holding only the numerator.
 */
library ABDKMath64x64 {
  /*
   * Minimum value signed 64.64-bit fixed point number may have. 
   */
  int128 private constant MIN_64x64 = -0x80000000000000000000000000000000;

  /*
   * Maximum value signed 64.64-bit fixed point number may have. 
   */
  int128 private constant MAX_64x64 = 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF;

  /**
   * Convert signed 256-bit integer number into signed 64.64-bit fixed point
   * number.  Revert on overflow.
   *
   * @param x signed 256-bit integer number
   * @return signed 64.64-bit fixed point number
   */
  function fromInt (int256 x) internal pure returns (int128) {
    unchecked {
      require (x >= -0x8000000000000000 && x <= 0x7FFFFFFFFFFFFFFF);
      return int128 (x << 64);
    }
  }

  /**
   * Convert signed 64.64 fixed point number into signed 64-bit integer number
   * rounding down.
   *
   * @param x signed 64.64-bit fixed point number
   * @return signed 64-bit integer number
   */
  function toInt (int128 x) internal pure returns (int64) {
    unchecked {
      return int64 (x >> 64);
    }
  }

  /**
   * Convert unsigned 256-bit integer number into signed 64.64-bit fixed point
   * number.  Revert on overflow.
   *
   * @param x unsigned 256-bit integer number
   * @return signed 64.64-bit fixed point number
   */
  function fromUInt (uint256 x) internal pure returns (int128) {
    unchecked {
      require (x <= 0x7FFFFFFFFFFFFFFF);
      return int128 (int256 (x << 64));
    }
  }

  /**
   * Convert signed 64.64 fixed point number into unsigned 64-bit integer
   * number rounding down.  Revert on underflow.
   *
   * @param x signed 64.64-bit fixed point number
   * @return unsigned 64-bit integer number
   */
  function toUInt (int128 x) internal pure returns (uint64) {
    unchecked {
      require (x >= 0);
      return uint64 (uint128 (x >> 64));
    }
  }

  /**
   * Convert signed 128.128 fixed point number into signed 64.64-bit fixed point
   * number rounding down.  Revert on overflow.
   *
   * @param x signed 128.128-bin fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function from128x128 (int256 x) internal pure returns (int128) {
    unchecked {
      int256 result = x >> 64;
      require (result >= MIN_64x64 && result <= MAX_64x64);
      return int128 (result);
    }
  }

  /**
   * Convert signed 64.64 fixed point number into signed 128.128 fixed point
   * number.
   *
   * @param x signed 64.64-bit fixed point number
   * @return signed 128.128 fixed point number
   */
  function to128x128 (int128 x) internal pure returns (int256) {
    unchecked {
      return int256 (x) << 64;
    }
  }

  /**
   * Calculate x + y.  Revert on overflow.
   *
   * @param x signed 64.64-bit fixed point number
   * @param y signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function add (int128 x, int128 y) internal pure returns (int128) {
    unchecked {
      int256 result = int256(x) + y;
      require (result >= MIN_64x64 && result <= MAX_64x64);
      return int128 (result);
    }
  }

  /**
   * Calculate x - y.  Revert on overflow.
   *
   * @param x signed 64.64-bit fixed point number
   * @param y signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function sub (int128 x, int128 y) internal pure returns (int128) {
    unchecked {
      int256 result = int256(x) - y;
      require (result >= MIN_64x64 && result <= MAX_64x64);
      return int128 (result);
    }
  }

  /**
   * Calculate x * y rounding down.  Revert on overflow.
   *
   * @param x signed 64.64-bit fixed point number
   * @param y signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function mul (int128 x, int128 y) internal pure returns (int128) {
    unchecked {
      int256 result = int256(x) * y >> 64;
      require (result >= MIN_64x64 && result <= MAX_64x64);
      return int128 (result);
    }
  }

  /**
   * Calculate x * y rounding towards zero, where x is signed 64.64 fixed point
   * number and y is signed 256-bit integer number.  Revert on overflow.
   *
   * @param x signed 64.64 fixed point number
   * @param y signed 256-bit integer number
   * @return signed 256-bit integer number
   */
  function muli (int128 x, int256 y) internal pure returns (int256) {
    unchecked {
      if (x == MIN_64x64) {
        require (y >= -0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF &&
          y <= 0x1000000000000000000000000000000000000000000000000);
        return -y << 63;
      } else {
        bool negativeResult = false;
        if (x < 0) {
          x = -x;
          negativeResult = true;
        }
        if (y < 0) {
          y = -y; // We rely on overflow behavior here
          negativeResult = !negativeResult;
        }
        uint256 absoluteResult = mulu (x, uint256 (y));
        if (negativeResult) {
          require (absoluteResult <=
            0x8000000000000000000000000000000000000000000000000000000000000000);
          return -int256 (absoluteResult); // We rely on overflow behavior here
        } else {
          require (absoluteResult <=
            0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
          return int256 (absoluteResult);
        }
      }
    }
  }

  /**
   * Calculate x * y rounding down, where x is signed 64.64 fixed point number
   * and y is unsigned 256-bit integer number.  Revert on overflow.
   *
   * @param x signed 64.64 fixed point number
   * @param y unsigned 256-bit integer number
   * @return unsigned 256-bit integer number
   */
  function mulu (int128 x, uint256 y) internal pure returns (uint256) {
    unchecked {
      if (y == 0) return 0;

      require (x >= 0);

      uint256 lo = (uint256 (int256 (x)) * (y & 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF)) >> 64;
      uint256 hi = uint256 (int256 (x)) * (y >> 128);

      require (hi <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
      hi <<= 64;

      require (hi <=
        0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF - lo);
      return hi + lo;
    }
  }

  /**
   * Calculate x / y rounding towards zero.  Revert on overflow or when y is
   * zero.
   *
   * @param x signed 64.64-bit fixed point number
   * @param y signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function div (int128 x, int128 y) internal pure returns (int128) {
    unchecked {
      require (y != 0);
      int256 result = (int256 (x) << 64) / y;
      require (result >= MIN_64x64 && result <= MAX_64x64);
      return int128 (result);
    }
  }

  /**
   * Calculate x / y rounding towards zero, where x and y are signed 256-bit
   * integer numbers.  Revert on overflow or when y is zero.
   *
   * @param x signed 256-bit integer number
   * @param y signed 256-bit integer number
   * @return signed 64.64-bit fixed point number
   */
  function divi (int256 x, int256 y) internal pure returns (int128) {
    unchecked {
      require (y != 0);

      bool negativeResult = false;
      if (x < 0) {
        x = -x; // We rely on overflow behavior here
        negativeResult = true;
      }
      if (y < 0) {
        y = -y; // We rely on overflow behavior here
        negativeResult = !negativeResult;
      }
      uint128 absoluteResult = divuu (uint256 (x), uint256 (y));
      if (negativeResult) {
        require (absoluteResult <= 0x80000000000000000000000000000000);
        return -int128 (absoluteResult); // We rely on overflow behavior here
      } else {
        require (absoluteResult <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
        return int128 (absoluteResult); // We rely on overflow behavior here
      }
    }
  }

  /**
   * Calculate x / y rounding towards zero, where x and y are unsigned 256-bit
   * integer numbers.  Revert on overflow or when y is zero.
   *
   * @param x unsigned 256-bit integer number
   * @param y unsigned 256-bit integer number
   * @return signed 64.64-bit fixed point number
   */
  function divu (uint256 x, uint256 y) internal pure returns (int128) {
    unchecked {
      require (y != 0);
      uint128 result = divuu (x, y);
      require (result <= uint128 (MAX_64x64));
      return int128 (result);
    }
  }

  /**
   * Calculate -x.  Revert on overflow.
   *
   * @param x signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function neg (int128 x) internal pure returns (int128) {
    unchecked {
      require (x != MIN_64x64);
      return -x;
    }
  }

  /**
   * Calculate |x|.  Revert on overflow.
   *
   * @param x signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function abs (int128 x) internal pure returns (int128) {
    unchecked {
      require (x != MIN_64x64);
      return x < 0 ? -x : x;
    }
  }

  /**
   * Calculate 1 / x rounding towards zero.  Revert on overflow or when x is
   * zero.
   *
   * @param x signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function inv (int128 x) internal pure returns (int128) {
    unchecked {
      require (x != 0);
      int256 result = int256 (0x100000000000000000000000000000000) / x;
      require (result >= MIN_64x64 && result <= MAX_64x64);
      return int128 (result);
    }
  }

  /**
   * Calculate arithmetics average of x and y, i.e. (x + y) / 2 rounding down.
   *
   * @param x signed 64.64-bit fixed point number
   * @param y signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function avg (int128 x, int128 y) internal pure returns (int128) {
    unchecked {
      return int128 ((int256 (x) + int256 (y)) >> 1);
    }
  }

  /**
   * Calculate geometric average of x and y, i.e. sqrt (x * y) rounding down.
   * Revert on overflow or in case x * y is negative.
   *
   * @param x signed 64.64-bit fixed point number
   * @param y signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function gavg (int128 x, int128 y) internal pure returns (int128) {
    unchecked {
      int256 m = int256 (x) * int256 (y);
      require (m >= 0);
      require (m <
          0x4000000000000000000000000000000000000000000000000000000000000000);
      return int128 (sqrtu (uint256 (m)));
    }
  }

  /**
   * Calculate x^y assuming 0^0 is 1, where x is signed 64.64 fixed point number
   * and y is unsigned 256-bit integer number.  Revert on overflow.
   *
   * @param x signed 64.64-bit fixed point number
   * @param y uint256 value
   * @return signed 64.64-bit fixed point number
   */
  function pow (int128 x, uint256 y) internal pure returns (int128) {
    unchecked {
      bool negative = x < 0 && y & 1 == 1;

      uint256 absX = uint128 (x < 0 ? -x : x);
      uint256 absResult;
      absResult = 0x100000000000000000000000000000000;

      if (absX <= 0x10000000000000000) {
        absX <<= 63;
        while (y != 0) {
          if (y & 0x1 != 0) {
            absResult = absResult * absX >> 127;
          }
          absX = absX * absX >> 127;

          if (y & 0x2 != 0) {
            absResult = absResult * absX >> 127;
          }
          absX = absX * absX >> 127;

          if (y & 0x4 != 0) {
            absResult = absResult * absX >> 127;
          }
          absX = absX * absX >> 127;

          if (y & 0x8 != 0) {
            absResult = absResult * absX >> 127;
          }
          absX = absX * absX >> 127;

          y >>= 4;
        }

        absResult >>= 64;
      } else {
        uint256 absXShift = 63;
        if (absX < 0x1000000000000000000000000) { absX <<= 32; absXShift -= 32; }
        if (absX < 0x10000000000000000000000000000) { absX <<= 16; absXShift -= 16; }
        if (absX < 0x1000000000000000000000000000000) { absX <<= 8; absXShift -= 8; }
        if (absX < 0x10000000000000000000000000000000) { absX <<= 4; absXShift -= 4; }
        if (absX < 0x40000000000000000000000000000000) { absX <<= 2; absXShift -= 2; }
        if (absX < 0x80000000000000000000000000000000) { absX <<= 1; absXShift -= 1; }

        uint256 resultShift = 0;
        while (y != 0) {
          require (absXShift < 64);

          if (y & 0x1 != 0) {
            absResult = absResult * absX >> 127;
            resultShift += absXShift;
            if (absResult > 0x100000000000000000000000000000000) {
              absResult >>= 1;
              resultShift += 1;
            }
          }
          absX = absX * absX >> 127;
          absXShift <<= 1;
          if (absX >= 0x100000000000000000000000000000000) {
              absX >>= 1;
              absXShift += 1;
          }

          y >>= 1;
        }

        require (resultShift < 64);
        absResult >>= 64 - resultShift;
      }
      int256 result = negative ? -int256 (absResult) : int256 (absResult);
      require (result >= MIN_64x64 && result <= MAX_64x64);
      return int128 (result);
    }
  }

  /**
   * Calculate sqrt (x) rounding down.  Revert if x < 0.
   *
   * @param x signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function sqrt (int128 x) internal pure returns (int128) {
    unchecked {
      require (x >= 0);
      return int128 (sqrtu (uint256 (int256 (x)) << 64));
    }
  }

  /**
   * Calculate binary logarithm of x.  Revert if x <= 0.
   *
   * @param x signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function log_2 (int128 x) internal pure returns (int128) {
    unchecked {
      require (x > 0);

      int256 msb = 0;
      int256 xc = x;
      if (xc >= 0x10000000000000000) { xc >>= 64; msb += 64; }
      if (xc >= 0x100000000) { xc >>= 32; msb += 32; }
      if (xc >= 0x10000) { xc >>= 16; msb += 16; }
      if (xc >= 0x100) { xc >>= 8; msb += 8; }
      if (xc >= 0x10) { xc >>= 4; msb += 4; }
      if (xc >= 0x4) { xc >>= 2; msb += 2; }
      if (xc >= 0x2) msb += 1;  // No need to shift xc anymore

      int256 result = msb - 64 << 64;
      uint256 ux = uint256 (int256 (x)) << uint256 (127 - msb);
      for (int256 bit = 0x8000000000000000; bit > 0; bit >>= 1) {
        ux *= ux;
        uint256 b = ux >> 255;
        ux >>= 127 + b;
        result += bit * int256 (b);
      }

      return int128 (result);
    }
  }

  /**
   * Calculate natural logarithm of x.  Revert if x <= 0.
   *
   * @param x signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function ln (int128 x) internal pure returns (int128) {
    unchecked {
      require (x > 0);

      return int128 (int256 (
          uint256 (int256 (log_2 (x))) * 0xB17217F7D1CF79ABC9E3B39803F2F6AF >> 128));
    }
  }

  /**
   * Calculate binary exponent of x.  Revert on overflow.
   *
   * @param x signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function exp_2 (int128 x) internal pure returns (int128) {
    unchecked {
      require (x < 0x400000000000000000); // Overflow

      if (x < -0x400000000000000000) return 0; // Underflow

      uint256 result = 0x80000000000000000000000000000000;

      if (x & 0x8000000000000000 > 0)
        result = result * 0x16A09E667F3BCC908B2FB1366EA957D3E >> 128;
      if (x & 0x4000000000000000 > 0)
        result = result * 0x1306FE0A31B7152DE8D5A46305C85EDEC >> 128;
      if (x & 0x2000000000000000 > 0)
        result = result * 0x1172B83C7D517ADCDF7C8C50EB14A791F >> 128;
      if (x & 0x1000000000000000 > 0)
        result = result * 0x10B5586CF9890F6298B92B71842A98363 >> 128;
      if (x & 0x800000000000000 > 0)
        result = result * 0x1059B0D31585743AE7C548EB68CA417FD >> 128;
      if (x & 0x400000000000000 > 0)
        result = result * 0x102C9A3E778060EE6F7CACA4F7A29BDE8 >> 128;
      if (x & 0x200000000000000 > 0)
        result = result * 0x10163DA9FB33356D84A66AE336DCDFA3F >> 128;
      if (x & 0x100000000000000 > 0)
        result = result * 0x100B1AFA5ABCBED6129AB13EC11DC9543 >> 128;
      if (x & 0x80000000000000 > 0)
        result = result * 0x10058C86DA1C09EA1FF19D294CF2F679B >> 128;
      if (x & 0x40000000000000 > 0)
        result = result * 0x1002C605E2E8CEC506D21BFC89A23A00F >> 128;
      if (x & 0x20000000000000 > 0)
        result = result * 0x100162F3904051FA128BCA9C55C31E5DF >> 128;
      if (x & 0x10000000000000 > 0)
        result = result * 0x1000B175EFFDC76BA38E31671CA939725 >> 128;
      if (x & 0x8000000000000 > 0)
        result = result * 0x100058BA01FB9F96D6CACD4B180917C3D >> 128;
      if (x & 0x4000000000000 > 0)
        result = result * 0x10002C5CC37DA9491D0985C348C68E7B3 >> 128;
      if (x & 0x2000000000000 > 0)
        result = result * 0x1000162E525EE054754457D5995292026 >> 128;
      if (x & 0x1000000000000 > 0)
        result = result * 0x10000B17255775C040618BF4A4ADE83FC >> 128;
      if (x & 0x800000000000 > 0)
        result = result * 0x1000058B91B5BC9AE2EED81E9B7D4CFAB >> 128;
      if (x & 0x400000000000 > 0)
        result = result * 0x100002C5C89D5EC6CA4D7C8ACC017B7C9 >> 128;
      if (x & 0x200000000000 > 0)
        result = result * 0x10000162E43F4F831060E02D839A9D16D >> 128;
      if (x & 0x100000000000 > 0)
        result = result * 0x100000B1721BCFC99D9F890EA06911763 >> 128;
      if (x & 0x80000000000 > 0)
        result = result * 0x10000058B90CF1E6D97F9CA14DBCC1628 >> 128;
      if (x & 0x40000000000 > 0)
        result = result * 0x1000002C5C863B73F016468F6BAC5CA2B >> 128;
      if (x & 0x20000000000 > 0)
        result = result * 0x100000162E430E5A18F6119E3C02282A5 >> 128;
      if (x & 0x10000000000 > 0)
        result = result * 0x1000000B1721835514B86E6D96EFD1BFE >> 128;
      if (x & 0x8000000000 > 0)
        result = result * 0x100000058B90C0B48C6BE5DF846C5B2EF >> 128;
      if (x & 0x4000000000 > 0)
        result = result * 0x10000002C5C8601CC6B9E94213C72737A >> 128;
      if (x & 0x2000000000 > 0)
        result = result * 0x1000000162E42FFF037DF38AA2B219F06 >> 128;
      if (x & 0x1000000000 > 0)
        result = result * 0x10000000B17217FBA9C739AA5819F44F9 >> 128;
      if (x & 0x800000000 > 0)
        result = result * 0x1000000058B90BFCDEE5ACD3C1CEDC823 >> 128;
      if (x & 0x400000000 > 0)
        result = result * 0x100000002C5C85FE31F35A6A30DA1BE50 >> 128;
      if (x & 0x200000000 > 0)
        result = result * 0x10000000162E42FF0999CE3541B9FFFCF >> 128;
      if (x & 0x100000000 > 0)
        result = result * 0x100000000B17217F80F4EF5AADDA45554 >> 128;
      if (x & 0x80000000 > 0)
        result = result * 0x10000000058B90BFBF8479BD5A81B51AD >> 128;
      if (x & 0x40000000 > 0)
        result = result * 0x1000000002C5C85FDF84BD62AE30A74CC >> 128;
      if (x & 0x20000000 > 0)
        result = result * 0x100000000162E42FEFB2FED257559BDAA >> 128;
      if (x & 0x10000000 > 0)
        result = result * 0x1000000000B17217F7D5A7716BBA4A9AE >> 128;
      if (x & 0x8000000 > 0)
        result = result * 0x100000000058B90BFBE9DDBAC5E109CCE >> 128;
      if (x & 0x4000000 > 0)
        result = result * 0x10000000002C5C85FDF4B15DE6F17EB0D >> 128;
      if (x & 0x2000000 > 0)
        result = result * 0x1000000000162E42FEFA494F1478FDE05 >> 128;
      if (x & 0x1000000 > 0)
        result = result * 0x10000000000B17217F7D20CF927C8E94C >> 128;
      if (x & 0x800000 > 0)
        result = result * 0x1000000000058B90BFBE8F71CB4E4B33D >> 128;
      if (x & 0x400000 > 0)
        result = result * 0x100000000002C5C85FDF477B662B26945 >> 128;
      if (x & 0x200000 > 0)
        result = result * 0x10000000000162E42FEFA3AE53369388C >> 128;
      if (x & 0x100000 > 0)
        result = result * 0x100000000000B17217F7D1D351A389D40 >> 128;
      if (x & 0x80000 > 0)
        result = result * 0x10000000000058B90BFBE8E8B2D3D4EDE >> 128;
      if (x & 0x40000 > 0)
        result = result * 0x1000000000002C5C85FDF4741BEA6E77E >> 128;
      if (x & 0x20000 > 0)
        result = result * 0x100000000000162E42FEFA39FE95583C2 >> 128;
      if (x & 0x10000 > 0)
        result = result * 0x1000000000000B17217F7D1CFB72B45E1 >> 128;
      if (x & 0x8000 > 0)
        result = result * 0x100000000000058B90BFBE8E7CC35C3F0 >> 128;
      if (x & 0x4000 > 0)
        result = result * 0x10000000000002C5C85FDF473E242EA38 >> 128;
      if (x & 0x2000 > 0)
        result = result * 0x1000000000000162E42FEFA39F02B772C >> 128;
      if (x & 0x1000 > 0)
        result = result * 0x10000000000000B17217F7D1CF7D83C1A >> 128;
      if (x & 0x800 > 0)
        result = result * 0x1000000000000058B90BFBE8E7BDCBE2E >> 128;
      if (x & 0x400 > 0)
        result = result * 0x100000000000002C5C85FDF473DEA871F >> 128;
      if (x & 0x200 > 0)
        result = result * 0x10000000000000162E42FEFA39EF44D91 >> 128;
      if (x & 0x100 > 0)
        result = result * 0x100000000000000B17217F7D1CF79E949 >> 128;
      if (x & 0x80 > 0)
        result = result * 0x10000000000000058B90BFBE8E7BCE544 >> 128;
      if (x & 0x40 > 0)
        result = result * 0x1000000000000002C5C85FDF473DE6ECA >> 128;
      if (x & 0x20 > 0)
        result = result * 0x100000000000000162E42FEFA39EF366F >> 128;
      if (x & 0x10 > 0)
        result = result * 0x1000000000000000B17217F7D1CF79AFA >> 128;
      if (x & 0x8 > 0)
        result = result * 0x100000000000000058B90BFBE8E7BCD6D >> 128;
      if (x & 0x4 > 0)
        result = result * 0x10000000000000002C5C85FDF473DE6B2 >> 128;
      if (x & 0x2 > 0)
        result = result * 0x1000000000000000162E42FEFA39EF358 >> 128;
      if (x & 0x1 > 0)
        result = result * 0x10000000000000000B17217F7D1CF79AB >> 128;

      result >>= uint256 (int256 (63 - (x >> 64)));
      require (result <= uint256 (int256 (MAX_64x64)));

      return int128 (int256 (result));
    }
  }

  /**
   * Calculate natural exponent of x.  Revert on overflow.
   *
   * @param x signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */
  function exp (int128 x) internal pure returns (int128) {
    unchecked {
      require (x < 0x400000000000000000); // Overflow

      if (x < -0x400000000000000000) return 0; // Underflow

      return exp_2 (
          int128 (int256 (x) * 0x171547652B82FE1777D0FFDA0D23A7D12 >> 128));
    }
  }

  /**
   * Calculate x / y rounding towards zero, where x and y are unsigned 256-bit
   * integer numbers.  Revert on overflow or when y is zero.
   *
   * @param x unsigned 256-bit integer number
   * @param y unsigned 256-bit integer number
   * @return unsigned 64.64-bit fixed point number
   */
  function divuu (uint256 x, uint256 y) private pure returns (uint128) {
    unchecked {
      require (y != 0);

      uint256 result;

      if (x <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF)
        result = (x << 64) / y;
      else {
        uint256 msb = 192;
        uint256 xc = x >> 192;
        if (xc >= 0x100000000) { xc >>= 32; msb += 32; }
        if (xc >= 0x10000) { xc >>= 16; msb += 16; }
        if (xc >= 0x100) { xc >>= 8; msb += 8; }
        if (xc >= 0x10) { xc >>= 4; msb += 4; }
        if (xc >= 0x4) { xc >>= 2; msb += 2; }
        if (xc >= 0x2) msb += 1;  // No need to shift xc anymore

        result = (x << 255 - msb) / ((y - 1 >> msb - 191) + 1);
        require (result <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);

        uint256 hi = result * (y >> 128);
        uint256 lo = result * (y & 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);

        uint256 xh = x >> 192;
        uint256 xl = x << 64;

        if (xl < lo) xh -= 1;
        xl -= lo; // We rely on overflow behavior here
        lo = hi << 128;
        if (xl < lo) xh -= 1;
        xl -= lo; // We rely on overflow behavior here

        assert (xh == hi >> 128);

        result += xl / y;
      }

      require (result <= 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF);
      return uint128 (result);
    }
  }

  /**
   * Calculate sqrt (x) rounding down, where x is unsigned 256-bit integer
   * number.
   *
   * @param x unsigned 256-bit integer number
   * @return unsigned 128-bit integer number
   */
  function sqrtu (uint256 x) private pure returns (uint128) {
    unchecked {
      if (x == 0) return 0;
      else {
        uint256 xx = x;
        uint256 r = 1;
        if (xx >= 0x100000000000000000000000000000000) { xx >>= 128; r <<= 64; }
        if (xx >= 0x10000000000000000) { xx >>= 64; r <<= 32; }
        if (xx >= 0x100000000) { xx >>= 32; r <<= 16; }
        if (xx >= 0x10000) { xx >>= 16; r <<= 8; }
        if (xx >= 0x100) { xx >>= 8; r <<= 4; }
        if (xx >= 0x10) { xx >>= 4; r <<= 2; }
        if (xx >= 0x8) { r <<= 1; }
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1;
        r = (r + x / r) >> 1; // Seven iterations should be enough
        uint256 r1 = x / r;
        return uint128 (r < r1 ? r : r1);
      }
    }
  }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/AccessControl.sol)

pragma solidity ^0.8.0;

import "./IAccessControl.sol";
import "../utils/Context.sol";
import "../utils/Strings.sol";
import "../utils/introspection/ERC165.sol";

/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms. This is a lightweight version that doesn't allow enumerating role
 * members except through off-chain means by accessing the contract event logs. Some
 * applications may benefit from on-chain enumerability, for those cases see
 * {AccessControlEnumerable}.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it.
 */
abstract contract AccessControl is Context, IAccessControl, ERC165 {
    struct RoleData {
        mapping(address => bool) members;
        bytes32 adminRole;
    }

    mapping(bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Modifier that checks that an account has a specific role. Reverts
     * with a standardized message including the required role.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     *
     * _Available since v4.1._
     */
    modifier onlyRole(bytes32 role) {
        _checkRole(role);
        _;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IAccessControl).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
        return _roles[role].members[account];
    }

    /**
     * @dev Revert with a standard message if `_msgSender()` is missing `role`.
     * Overriding this function changes the behavior of the {onlyRole} modifier.
     *
     * Format of the revert message is described in {_checkRole}.
     *
     * _Available since v4.6._
     */
    function _checkRole(bytes32 role) internal view virtual {
        _checkRole(role, _msgSender());
    }

    /**
     * @dev Revert with a standard message if `account` is missing `role`.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
     */
    function _checkRole(bytes32 role, address account) internal view virtual {
        if (!hasRole(role, account)) {
            revert(
                string(
                    abi.encodePacked(
                        "AccessControl: account ",
                        Strings.toHexString(uint160(account), 20),
                        " is missing role ",
                        Strings.toHexString(uint256(role), 32)
                    )
                )
            );
        }
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     *
     * May emit a {RoleGranted} event.
     */
    function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     *
     * May emit a {RoleRevoked} event.
     */
    function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been revoked `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     *
     * May emit a {RoleRevoked} event.
     */
    function renounceRole(bytes32 role, address account) public virtual override {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * May emit a {RoleGranted} event.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     *
     * NOTE: This function is deprecated in favor of {_grantRole}.
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        bytes32 previousAdminRole = getRoleAdmin(role);
        _roles[role].adminRole = adminRole;
        emit RoleAdminChanged(role, previousAdminRole, adminRole);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * Internal function without access restriction.
     *
     * May emit a {RoleGranted} event.
     */
    function _grantRole(bytes32 role, address account) internal virtual {
        if (!hasRole(role, account)) {
            _roles[role].members[account] = true;
            emit RoleGranted(role, account, _msgSender());
        }
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * Internal function without access restriction.
     *
     * May emit a {RoleRevoked} event.
     */
    function _revokeRole(bytes32 role, address account) internal virtual {
        if (hasRole(role, account)) {
            _roles[role].members[account] = false;
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly
                /// @solidity memory-safe-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @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 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.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/AccessControl.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

contract Drainable is AccessControl {
	bytes32 public constant DRAINER_ADMIN = keccak256("DRAINER_ADMIN");
	bytes32 public constant DRAINER = keccak256("DRAINER");

    constructor() {
        _grantRole(DRAINER_ADMIN, msg.sender);
        _setRoleAdmin(DRAINER, DRAINER_ADMIN);
        grantRole(DRAINER, msg.sender);
    }

    modifier onlyAdmin {
        require(hasRole(DRAINER, msg.sender), "err-invalid-drainer");
        _;
    }

    function drain(address _token, address _receiver, uint256 _amount) external onlyAdmin {
        IERC20(_token).transfer(_receiver, _amount);
    }

    function drainETH(address payable _receiver, uint256 _amount) external onlyAdmin {
        (bool success) = _receiver.send(_amount);
        require(success);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;

import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/Address.sol";
import "../../utils/Context.sol";
import "../../utils/Strings.sol";
import "../../utils/introspection/ERC165.sol";

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping(address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    /**
     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return
            interfaceId == type(IERC721).interfaceId ||
            interfaceId == type(IERC721Metadata).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: address zero is not a valid owner");
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _owners[tokenId];
        require(owner != address(0), "ERC721: invalid token ID");
        return owner;
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        _requireMinted(tokenId);

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

    /**
     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
     * by default, can be overridden in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not token owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        _requireMinted(tokenId);

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        _setApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner nor approved");

        _transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes memory data
    ) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner nor approved");
        _safeTransfer(from, to, tokenId, data);
    }

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * `data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(
        address from,
        address to,
        uint256 tokenId,
        bytes memory data
    ) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _owners[tokenId] != address(0);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || isApprovedForAll(owner, spender) || getApproved(tokenId) == spender);
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeMint(
        address to,
        uint256 tokenId,
        bytes memory data
    ) internal virtual {
        _mint(to, tokenId);
        require(
            _checkOnERC721Received(address(0), to, tokenId, data),
            "ERC721: transfer to non ERC721Receiver implementer"
        );
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId);

        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(address(0), to, tokenId);

        _afterTokenTransfer(address(0), to, tokenId);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Clear approvals
        _approve(address(0), tokenId);

        _balances[owner] -= 1;
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);

        _afterTokenTransfer(owner, address(0), tokenId);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

        // Clear approvals from the previous owner
        _approve(address(0), tokenId);

        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);

        _afterTokenTransfer(from, to, tokenId);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits an {Approval} event.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
    }

    /**
     * @dev Approve `operator` to operate on all of `owner` tokens
     *
     * Emits an {ApprovalForAll} event.
     */
    function _setApprovalForAll(
        address owner,
        address operator,
        bool approved
    ) internal virtual {
        require(owner != operator, "ERC721: approve to caller");
        _operatorApprovals[owner][operator] = approved;
        emit ApprovalForAll(owner, operator, approved);
    }

    /**
     * @dev Reverts if the `tokenId` has not been minted yet.
     */
    function _requireMinted(uint256 tokenId) internal view virtual {
        require(_exists(tokenId), "ERC721: invalid token ID");
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory data
    ) private returns (bool) {
        if (to.isContract()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, data) returns (bytes4 retval) {
                return retval == IERC721Receiver.onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    /// @solidity memory-safe-assembly
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/IAccessControl.sol)

pragma solidity ^0.8.0;

/**
 * @dev External interface of AccessControl declared to support ERC165 detection.
 */
interface IAccessControl {
    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {AccessControl-_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) external view returns (bool);

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {AccessControl-_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) external view returns (bytes32);

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) external;

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) external;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);

    /**
     * @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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from,
        address to,
        uint256 amount
    ) external returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @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.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the 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 virtual onlyOwner {
        _transferOwnership(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 virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";

contract Pausable is Ownable {
    bool public paused;

    modifier ifNotPaused {
        require(!paused, "err-paused");
        _;
    }

    function pause() external onlyOwner {
        paused = true;
    }

    function unpause() external onlyOwner {
        paused = false;
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity ^0.8.15;

library Rates {
    function convertDefault(uint256 _amount, uint256 _exchangeRate, uint8 _decimals) public pure returns (uint256) {
        return _amount * _exchangeRate / 10 ** _decimals;
    }

    function convertInverse(uint256 _amount, uint256 _exchangeRate, uint8 _decimals) public pure returns (uint256) {
        return 10 ** _decimals * _amount / _exchangeRate;
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity 0.8.15;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "contracts/Stage2/StandardTokenGateway.sol";
import "contracts/Pausable.sol";
import "contracts/Rates.sol";
import "contracts/Drainable.sol";

contract Staking is ERC721, Ownable, Pausable, Drainable {
    uint256 private _tokenId;
    uint256 private immutable RATE_FACTOR = 10 ** 5;
    uint8 private immutable RATE_DEC = 5;

    // Standard Token data feed
    StandardTokenGateway public tokenGateway;

    bool public active;                 // active or not, needs to be set manually
    bool public isCatastrophe;          // in the event of a catastrophe, let users withdraw

    uint256 public windowStart;         // the start time for the 'stake'
    uint256 public windowEnd;           // the end time for the 'stake'
    uint256 public maturity;            // the maturity date
    uint256 public initialisedAt;       // the time of contract initialisation (epoch time)
    uint256 public allocatedSeuro;      // the amount of seuro allocated, inc rewards

    address public immutable TST_ADDRESS;
    address public immutable SEURO_ADDRESS;
    uint256 public immutable SI_RATE;   // simple interest rate for the bond (factor of 10 ** 5)
    uint256 public immutable minTST;    // the allowed minimum amount of TST to bond

    mapping(address => Position) private _positions;

    struct Position { uint96 nonce; uint256 tokenId; bool open; uint256 stake; uint256 reward; bool burned; }

    event Mint(address indexed user, uint256 stake, uint256 allocatedSeuro);
    event Burn(address indexed user, uint256 stake, uint256 reward, uint256 allocatedSeuro);
    event Withdraw(address indexed user, uint256 amount);

    constructor(string memory _name, string memory _symbol, uint256 _start, uint256 _end, uint256 _maturity, address _gatewayAddress, address _standardAddress, address _seuroAddress, uint256 _si) ERC721(_name, _symbol) {
        tokenGateway = StandardTokenGateway(_gatewayAddress);
        SI_RATE = _si;
        TST_ADDRESS = _standardAddress;
        SEURO_ADDRESS = _seuroAddress;
        windowStart = _start;
        windowEnd = _end;
        maturity = _maturity;
        initialisedAt = block.timestamp;
        minTST = 1 ether;
    }

    function activate() external onlyOwner { require(active == false, "err-already-active"); active = true; }

    function disable() external onlyOwner { require(active, "err-not-active"); active = false; }

    // calculates the reward in SEURO based in the input of amount of TSTs
    function calculateReward(uint256 _amount) public view returns (uint256 reward) {
        uint256 tstReward = Rates.convertDefault(_amount, SI_RATE, RATE_DEC);
        return Rates.convertDefault(tstReward, tokenGateway.priceTstEur(), tokenGateway.priceDec());
    }

    // fetches the balance of the contract for the give erc20 token
    function balance(address _address) public view returns (uint256) { return IERC20(_address).balanceOf(address(this)); }

    // fetches the remaining about of tokens in the contract
    function remaining(address _address) public view returns (uint256) { return balance(_address) - allocatedSeuro; }

    // Main API to begin staking
    function mint(uint256 _amount) external ifNotPaused {
        require(active == true, "err-not-active");
        require(_amount >= minTST, "err-not-min");
        require(block.timestamp >= windowStart, "err-not-started");
        require(block.timestamp < windowEnd, "err-finished");

        // calculate the reward so we can also update the remaining SEURO
        uint256 reward = calculateReward(_amount);
        require(remaining(SEURO_ADDRESS) >= reward, "err-overlimit");

        // Transfer funds from sender to this contract
        // TODO send to some other guy not this contract!

        IERC20(TST_ADDRESS).transferFrom(msg.sender, address(this), _amount);

        Position memory pos = _positions[msg.sender];
        require(pos.burned == false, "err-already-claimed");

        if (pos.nonce == 0) {
            _mint(msg.sender, ++_tokenId);

            pos.open = true;
            pos.tokenId = _tokenId;
        }

        // update the position
        pos.stake += _amount;
        pos.nonce += 1;
        pos.reward += reward;

        // update the position
        _positions[msg.sender] = pos;

        // update the rewards in SEUR to be paid out
        allocatedSeuro += reward;

        emit Mint(msg.sender, _amount, allocatedSeuro);
    }

    function burn() external ifNotPaused {
        require(block.timestamp >= maturity, "err-maturity");

        Position storage pos = _positions[msg.sender];
        require(pos.nonce > 0, "err-not-valid");
        require(pos.open == true, "err-closed");

        // burn the token
        _burn(pos.tokenId);

        // transfer stake
        IERC20(TST_ADDRESS).transfer(msg.sender, pos.stake);
        // transfer reward
        IERC20(SEURO_ADDRESS).transfer(msg.sender, pos.reward);

        // update position states
        pos.open = false;
        pos.burned = true;

        allocatedSeuro -= pos.reward;

        emit Burn(msg.sender, pos.stake, pos.reward, allocatedSeuro);
    }

    // withdraw to the owner's address
    function withdraw(address _address) external onlyOwner {
        uint256 bal = IERC20(_address).balanceOf(address(this));

        require(bal > 0, "err-no-funds");
        IERC20(_address).transfer(owner(), bal);

        emit Withdraw(_address, bal);
    }

    function position(address owner) external view returns (Position memory) { return _positions[owner]; }

    function enableCatastrophe() external onlyOwner {
        require(active == true, "err-already-active");
        require(isCatastrophe == false, "err-already-isCatastrophe");
        isCatastrophe = true;
        active = false;
    }

    function disableCatastrophe() external onlyOwner {
        require(active == false, "err-already-active");
        require(isCatastrophe == true, "err-already-isCatastrophe-false");
        isCatastrophe = false;
        active = true;
    }

    function emergencyWithdraw() external {
        require(isCatastrophe == true, "err-not-catastrophe");

        Position memory pos = _positions[msg.sender];
        require(pos.nonce > 0, "err-no-position");
        require(pos.open == true, "err-postition-closed");

        IERC20(TST_ADDRESS).transfer(msg.sender, pos.stake);

        // closed for business
        pos.open = false;

        // burn the token
        _burn(pos.tokenId);

        _positions[msg.sender] = pos;

        emit Withdraw(msg.sender, pos.stake);
    }

    function setTokenGateway(address _tokenGateway) external {
        require(_tokenGateway != address(0), "err-invalid-gateway");
        tokenGateway = StandardTokenGateway(_tokenGateway);
    }

    // both erc721 and access control include supportsInterface, need to override both
    // explanation here: https://forum.openzeppelin.com/t/derived-contract-must-override-function-supportsinterface/6315/5
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC721, AccessControl) returns (bool) {
        return super.supportsInterface(interfaceId);
    }
}

// SPDX-License-Identifier: GPL-3.0-or-later
pragma solidity 0.8.15;

import "@openzeppelin/contracts/access/AccessControl.sol";
import "abdk-libraries-solidity/ABDKMath64x64.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

// StandardTokenGateway holds TSTs and acts as a standard token data feed with:
// - price per token in sEURO;
// - amount of obtainable tokens as bonding rewards left
contract StandardTokenGateway is AccessControl {

    // Reward token (TST)
    IERC20 public immutable TOKEN;

    uint256 public priceTstEur = 5500000;
    uint8 public priceDec = 8;

    // The amount of TST available to get as bond reward
    uint256 public bondRewardPoolSupply = 0;

    // By default enabled.
    // False when token transfers are disabled.
    bool private isActive = true;

    // The storage address
    address public storageAddress;

    bytes32 public constant TST_TOKEN_GATEWAY = keccak256("TST_TOKEN_GATEWAY");

    event Reward(address indexed user, uint256 amount);
    event RewardSupply(uint256 amount);

    constructor(address _tokenAddress) {
        _setupRole(TST_TOKEN_GATEWAY, msg.sender);
        TOKEN = IERC20(_tokenAddress);
    }

    modifier onlyGatewayOwner {
        require(hasRole(TST_TOKEN_GATEWAY, msg.sender), "invalid-gateway-owner");
        _;
    }

    modifier onlyStorageOwner {
        require(msg.sender == storageAddress, "err-not-storage-caller");
        _;
    }

    modifier isActivated {
        require(isActive == true, "err-in-maintenance");
        _;
    }

    function deactivateSystem() external onlyGatewayOwner {
        isActive = false;
    }

    function activateSystem() external onlyGatewayOwner {
        isActive = true;
    }

    function setTstEurPrice(uint256 _price, uint8 _dec) external onlyGatewayOwner {
        priceTstEur = _price;
        priceDec = _dec;
    }

    function updateRewardSupply() external {
        bondRewardPoolSupply = TOKEN.balanceOf(address(this));

        emit RewardSupply(bondRewardPoolSupply);
    }

    modifier enoughBalance(uint256 _toSend) {
        uint256 currBalance = TOKEN.balanceOf(address(this));
        require(currBalance > _toSend, "err-insufficient-tokens");
        _;
    }

    function setStorageAddress(address _newAddress) external onlyGatewayOwner {
        require(_newAddress != address(0), "err-zero-address");
        storageAddress = _newAddress;
    }

    function decreaseRewardSupply(uint256 _amount) external onlyStorageOwner enoughBalance(_amount) {
        require(bondRewardPoolSupply - _amount > 0, "dec-supply-uf");
        bondRewardPoolSupply -= _amount;

        emit RewardSupply(bondRewardPoolSupply);
    }

    function transferReward(address _toUser, uint256 _amount) external onlyStorageOwner isActivated enoughBalance(_amount) {
        TOKEN.transfer(_toUser, _amount);

        emit Reward(_toUser, _amount);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
    uint8 private constant _ADDRESS_LENGTH = 20;

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }
}

{
  "compilationTarget": {
    "contracts/Stage3/Staking.sol": "Staking"
  },
  "evmVersion": "london",
  "libraries": {
    "contracts/Rates.sol:Rates": "0x298c763988e62b72aab5fd3f944daac0124bcb0e"
  },
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}