creation_sourcecode: // SPDX-License-Identifier: MIT
  
  // File: @openzeppelin/contracts/utils/math/SafeMath.sol
  
  
  // OpenZeppelin Contracts (last updated v4.9.0) (utils/math/SafeMath.sol)
  
  pragma solidity ^0.8.0;
  
  // CAUTION
  // This version of SafeMath should only be used with Solidity 0.8 or later,
  // because it relies on the compiler's built in overflow checks.
  
  /**
   * @dev Wrappers over Solidity's arithmetic operations.
   *
   * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
   * now has built in overflow checking.
   */
  library SafeMath {
      /**
       * @dev Returns the addition of two unsigned integers, with an overflow flag.
       *
       * _Available since v3.4._
       */
      function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
          unchecked {
              uint256 c = a + b;
              if (c < a) return (false, 0);
              return (true, c);
          }
      }
  
      /**
       * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
       *
       * _Available since v3.4._
       */
      function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
          unchecked {
              if (b > a) return (false, 0);
              return (true, a - b);
          }
      }
  
      /**
       * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
       *
       * _Available since v3.4._
       */
      function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
          unchecked {
              // 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 (true, 0);
              uint256 c = a * b;
              if (c / a != b) return (false, 0);
              return (true, c);
          }
      }
  
      /**
       * @dev Returns the division of two unsigned integers, with a division by zero flag.
       *
       * _Available since v3.4._
       */
      function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
          unchecked {
              if (b == 0) return (false, 0);
              return (true, a / b);
          }
      }
  
      /**
       * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
       *
       * _Available since v3.4._
       */
      function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
          unchecked {
              if (b == 0) return (false, 0);
              return (true, a % b);
          }
      }
  
      /**
       * @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) {
          return a + b;
      }
  
      /**
       * @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 a - b;
      }
  
      /**
       * @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) {
          return a * b;
      }
  
      /**
       * @dev Returns the integer division of two unsigned integers, reverting on
       * division by zero. The result is rounded towards zero.
       *
       * Counterpart to Solidity's `/` operator.
       *
       * Requirements:
       *
       * - The divisor cannot be zero.
       */
      function div(uint256 a, uint256 b) internal pure returns (uint256) {
          return a / b;
      }
  
      /**
       * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
       * reverting 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 a % b;
      }
  
      /**
       * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
       * overflow (when the result is negative).
       *
       * CAUTION: This function is deprecated because it requires allocating memory for the error
       * message unnecessarily. For custom revert reasons use {trySub}.
       *
       * Counterpart to Solidity's `-` operator.
       *
       * Requirements:
       *
       * - Subtraction cannot overflow.
       */
      function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
          unchecked {
              require(b <= a, errorMessage);
              return a - b;
          }
      }
  
      /**
       * @dev Returns the integer division of two unsigned integers, reverting 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.
       */
      function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
          unchecked {
              require(b > 0, errorMessage);
              return a / b;
          }
      }
  
      /**
       * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
       * reverting with custom message when dividing by zero.
       *
       * CAUTION: This function is deprecated because it requires allocating memory for the error
       * message unnecessarily. For custom revert reasons use {tryMod}.
       *
       * 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, string memory errorMessage) internal pure returns (uint256) {
          unchecked {
              require(b > 0, errorMessage);
              return a % b;
          }
      }
  }
  
  // File: @openzeppelin/contracts/utils/math/Math.sol
  
  
  // OpenZeppelin Contracts (last updated v5.0.0) (utils/math/Math.sol)
  
  pragma solidity ^0.8.20;
  
  /**
   * @dev Standard math utilities missing in the Solidity language.
   */
  library Math {
      /**
       * @dev Muldiv operation overflow.
       */
      error MathOverflowedMulDiv();
  
      enum Rounding {
          Floor, // Toward negative infinity
          Ceil, // Toward positive infinity
          Trunc, // Toward zero
          Expand // Away from zero
      }
  
      /**
       * @dev Returns the addition of two unsigned integers, with an overflow flag.
       */
      function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
          unchecked {
              uint256 c = a + b;
              if (c < a) return (false, 0);
              return (true, c);
          }
      }
  
      /**
       * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
       */
      function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
          unchecked {
              if (b > a) return (false, 0);
              return (true, a - b);
          }
      }
  
      /**
       * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
       */
      function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
          unchecked {
              // 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 (true, 0);
              uint256 c = a * b;
              if (c / a != b) return (false, 0);
              return (true, c);
          }
      }
  
      /**
       * @dev Returns the division of two unsigned integers, with a division by zero flag.
       */
      function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
          unchecked {
              if (b == 0) return (false, 0);
              return (true, a / b);
          }
      }
  
      /**
       * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
       */
      function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
          unchecked {
              if (b == 0) return (false, 0);
              return (true, a % b);
          }
      }
  
      /**
       * @dev Returns the largest of two numbers.
       */
      function max(uint256 a, uint256 b) internal pure returns (uint256) {
          return a > b ? a : b;
      }
  
      /**
       * @dev Returns the smallest of two numbers.
       */
      function min(uint256 a, uint256 b) internal pure returns (uint256) {
          return a < b ? a : b;
      }
  
      /**
       * @dev Returns the average of two numbers. The result is rounded towards
       * zero.
       */
      function average(uint256 a, uint256 b) internal pure returns (uint256) {
          // (a + b) / 2 can overflow.
          return (a & b) + (a ^ b) / 2;
      }
  
      /**
       * @dev Returns the ceiling of the division of two numbers.
       *
       * This differs from standard division with `/` in that it rounds towards infinity instead
       * of rounding towards zero.
       */
      function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
          if (b == 0) {
              // Guarantee the same behavior as in a regular Solidity division.
              return a / b;
          }
  
          // (a + b - 1) / b can overflow on addition, so we distribute.
          return a == 0 ? 0 : (a - 1) / b + 1;
      }
  
      /**
       * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or
       * denominator == 0.
       * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv) with further edits by
       * Uniswap Labs also under MIT license.
       */
      function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
          unchecked {
              // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
              // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
              // variables such that product = prod1 * 2^256 + prod0.
              uint256 prod0 = x * y; // Least significant 256 bits of the product
              uint256 prod1; // Most significant 256 bits of the product
              assembly {
                  let mm := mulmod(x, y, not(0))
                  prod1 := sub(sub(mm, prod0), lt(mm, prod0))
              }
  
              // Handle non-overflow cases, 256 by 256 division.
              if (prod1 == 0) {
                  // Solidity will revert if denominator == 0, unlike the div opcode on its own.
                  // The surrounding unchecked block does not change this fact.
                  // See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
                  return prod0 / denominator;
              }
  
              // Make sure the result is less than 2^256. Also prevents denominator == 0.
              if (denominator <= prod1) {
                  revert MathOverflowedMulDiv();
              }
  
              ///////////////////////////////////////////////
              // 512 by 256 division.
              ///////////////////////////////////////////////
  
              // Make division exact by subtracting the remainder from [prod1 prod0].
              uint256 remainder;
              assembly {
                  // Compute remainder using mulmod.
                  remainder := mulmod(x, y, denominator)
  
                  // Subtract 256 bit number from 512 bit number.
                  prod1 := sub(prod1, gt(remainder, prod0))
                  prod0 := sub(prod0, remainder)
              }
  
              // Factor powers of two out of denominator and compute largest power of two divisor of denominator.
              // Always >= 1. See https://cs.stackexchange.com/q/138556/92363.
  
              uint256 twos = denominator & (0 - denominator);
              assembly {
                  // Divide denominator by twos.
                  denominator := div(denominator, twos)
  
                  // Divide [prod1 prod0] by twos.
                  prod0 := div(prod0, twos)
  
                  // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                  twos := add(div(sub(0, twos), twos), 1)
              }
  
              // Shift in bits from prod1 into prod0.
              prod0 |= prod1 * twos;
  
              // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
              // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
              // four bits. That is, denominator * inv = 1 mod 2^4.
              uint256 inverse = (3 * denominator) ^ 2;
  
              // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also
              // works in modular arithmetic, doubling the correct bits in each step.
              inverse *= 2 - denominator * inverse; // inverse mod 2^8
              inverse *= 2 - denominator * inverse; // inverse mod 2^16
              inverse *= 2 - denominator * inverse; // inverse mod 2^32
              inverse *= 2 - denominator * inverse; // inverse mod 2^64
              inverse *= 2 - denominator * inverse; // inverse mod 2^128
              inverse *= 2 - denominator * inverse; // inverse mod 2^256
  
              // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
              // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
              // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
              // is no longer required.
              result = prod0 * inverse;
              return result;
          }
      }
  
      /**
       * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
       */
      function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
          uint256 result = mulDiv(x, y, denominator);
          if (unsignedRoundsUp(rounding) && mulmod(x, y, denominator) > 0) {
              result += 1;
          }
          return result;
      }
  
      /**
       * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded
       * towards zero.
       *
       * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
       */
      function sqrt(uint256 a) internal pure returns (uint256) {
          if (a == 0) {
              return 0;
          }
  
          // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
          //
          // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
          // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
          //
          // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
          // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
          // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
          //
          // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
          uint256 result = 1 << (log2(a) >> 1);
  
          // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
          // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
          // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
          // into the expected uint128 result.
          unchecked {
              result = (result + a / result) >> 1;
              result = (result + a / result) >> 1;
              result = (result + a / result) >> 1;
              result = (result + a / result) >> 1;
              result = (result + a / result) >> 1;
              result = (result + a / result) >> 1;
              result = (result + a / result) >> 1;
              return min(result, a / result);
          }
      }
  
      /**
       * @notice Calculates sqrt(a), following the selected rounding direction.
       */
      function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
          unchecked {
              uint256 result = sqrt(a);
              return result + (unsignedRoundsUp(rounding) && result * result < a ? 1 : 0);
          }
      }
  
      /**
       * @dev Return the log in base 2 of a positive value rounded towards zero.
       * Returns 0 if given 0.
       */
      function log2(uint256 value) internal pure returns (uint256) {
          uint256 result = 0;
          unchecked {
              if (value >> 128 > 0) {
                  value >>= 128;
                  result += 128;
              }
              if (value >> 64 > 0) {
                  value >>= 64;
                  result += 64;
              }
              if (value >> 32 > 0) {
                  value >>= 32;
                  result += 32;
              }
              if (value >> 16 > 0) {
                  value >>= 16;
                  result += 16;
              }
              if (value >> 8 > 0) {
                  value >>= 8;
                  result += 8;
              }
              if (value >> 4 > 0) {
                  value >>= 4;
                  result += 4;
              }
              if (value >> 2 > 0) {
                  value >>= 2;
                  result += 2;
              }
              if (value >> 1 > 0) {
                  result += 1;
              }
          }
          return result;
      }
  
      /**
       * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
       * Returns 0 if given 0.
       */
      function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
          unchecked {
              uint256 result = log2(value);
              return result + (unsignedRoundsUp(rounding) && 1 << result < value ? 1 : 0);
          }
      }
  
      /**
       * @dev Return the log in base 10 of a positive value rounded towards zero.
       * Returns 0 if given 0.
       */
      function log10(uint256 value) internal pure returns (uint256) {
          uint256 result = 0;
          unchecked {
              if (value >= 10 ** 64) {
                  value /= 10 ** 64;
                  result += 64;
              }
              if (value >= 10 ** 32) {
                  value /= 10 ** 32;
                  result += 32;
              }
              if (value >= 10 ** 16) {
                  value /= 10 ** 16;
                  result += 16;
              }
              if (value >= 10 ** 8) {
                  value /= 10 ** 8;
                  result += 8;
              }
              if (value >= 10 ** 4) {
                  value /= 10 ** 4;
                  result += 4;
              }
              if (value >= 10 ** 2) {
                  value /= 10 ** 2;
                  result += 2;
              }
              if (value >= 10 ** 1) {
                  result += 1;
              }
          }
          return result;
      }
  
      /**
       * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
       * Returns 0 if given 0.
       */
      function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
          unchecked {
              uint256 result = log10(value);
              return result + (unsignedRoundsUp(rounding) && 10 ** result < value ? 1 : 0);
          }
      }
  
      /**
       * @dev Return the log in base 256 of a positive value rounded towards zero.
       * Returns 0 if given 0.
       *
       * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
       */
      function log256(uint256 value) internal pure returns (uint256) {
          uint256 result = 0;
          unchecked {
              if (value >> 128 > 0) {
                  value >>= 128;
                  result += 16;
              }
              if (value >> 64 > 0) {
                  value >>= 64;
                  result += 8;
              }
              if (value >> 32 > 0) {
                  value >>= 32;
                  result += 4;
              }
              if (value >> 16 > 0) {
                  value >>= 16;
                  result += 2;
              }
              if (value >> 8 > 0) {
                  result += 1;
              }
          }
          return result;
      }
  
      /**
       * @dev Return the log in base 256, following the selected rounding direction, of a positive value.
       * Returns 0 if given 0.
       */
      function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
          unchecked {
              uint256 result = log256(value);
              return result + (unsignedRoundsUp(rounding) && 1 << (result << 3) < value ? 1 : 0);
          }
      }
  
      /**
       * @dev Returns whether a provided rounding mode is considered rounding up for unsigned integers.
       */
      function unsignedRoundsUp(Rounding rounding) internal pure returns (bool) {
          return uint8(rounding) % 2 == 1;
      }
  }
  
  // File: @openzeppelin/contracts/token/ERC20/IERC20.sol
  
  
  // OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/IERC20.sol)
  
  pragma solidity ^0.8.20;
  
  /**
   * @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 value of tokens in existence.
       */
      function totalSupply() external view returns (uint256);
  
      /**
       * @dev Returns the value of tokens owned by `account`.
       */
      function balanceOf(address account) external view returns (uint256);
  
      /**
       * @dev Moves a `value` amount of 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 value) 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 a `value` amount of tokens 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 value) external returns (bool);
  
      /**
       * @dev Moves a `value` amount of tokens from `from` to `to` using the
       * allowance mechanism. `value` 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 value) external returns (bool);
  }
  
  // File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Permit.sol
  
  
  // OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/extensions/IERC20Permit.sol)
  
  pragma solidity ^0.8.20;
  
  /**
   * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
   * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
   *
   * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
   * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
   * need to send a transaction, and thus is not required to hold Ether at all.
   *
   * ==== Security Considerations
   *
   * There are two important considerations concerning the use of `permit`. The first is that a valid permit signature
   * expresses an allowance, and it should not be assumed to convey additional meaning. In particular, it should not be
   * considered as an intention to spend the allowance in any specific way. The second is that because permits have
   * built-in replay protection and can be submitted by anyone, they can be frontrun. A protocol that uses permits should
   * take this into consideration and allow a `permit` call to fail. Combining these two aspects, a pattern that may be
   * generally recommended is:
   *
   * ```solidity
   * function doThingWithPermit(..., uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public {
   *     try token.permit(msg.sender, address(this), value, deadline, v, r, s) {} catch {}
   *     doThing(..., value);
   * }
   *
   * function doThing(..., uint256 value) public {
   *     token.safeTransferFrom(msg.sender, address(this), value);
   *     ...
   * }
   * ```
   *
   * Observe that: 1) `msg.sender` is used as the owner, leaving no ambiguity as to the signer intent, and 2) the use of
   * `try/catch` allows the permit to fail and makes the code tolerant to frontrunning. (See also
   * {SafeERC20-safeTransferFrom}).
   *
   * Additionally, note that smart contract wallets (such as Argent or Safe) are not able to produce permit signatures, so
   * contracts should have entry points that don't rely on permit.
   */
  interface IERC20Permit {
      /**
       * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
       * given ``owner``'s signed approval.
       *
       * IMPORTANT: The same issues {IERC20-approve} has related to transaction
       * ordering also apply here.
       *
       * Emits an {Approval} event.
       *
       * Requirements:
       *
       * - `spender` cannot be the zero address.
       * - `deadline` must be a timestamp in the future.
       * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
       * over the EIP712-formatted function arguments.
       * - the signature must use ``owner``'s current nonce (see {nonces}).
       *
       * For more information on the signature format, see the
       * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
       * section].
       *
       * CAUTION: See Security Considerations above.
       */
      function permit(
          address owner,
          address spender,
          uint256 value,
          uint256 deadline,
          uint8 v,
          bytes32 r,
          bytes32 s
      ) external;
  
      /**
       * @dev Returns the current nonce for `owner`. This value must be
       * included whenever a signature is generated for {permit}.
       *
       * Every successful call to {permit} increases ``owner``'s nonce by one. This
       * prevents a signature from being used multiple times.
       */
      function nonces(address owner) external view returns (uint256);
  
      /**
       * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
       */
      // solhint-disable-next-line func-name-mixedcase
      function DOMAIN_SEPARATOR() external view returns (bytes32);
  }
  
  // File: @openzeppelin/contracts/utils/Address.sol
  
  
  // OpenZeppelin Contracts (last updated v5.0.0) (utils/Address.sol)
  
  pragma solidity ^0.8.20;
  
  /**
   * @dev Collection of functions related to the address type
   */
  library Address {
      /**
       * @dev The ETH balance of the account is not enough to perform the operation.
       */
      error AddressInsufficientBalance(address account);
  
      /**
       * @dev There's no code at `target` (it is not a contract).
       */
      error AddressEmptyCode(address target);
  
      /**
       * @dev A call to an address target failed. The target may have reverted.
       */
      error FailedInnerCall();
  
      /**
       * @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://consensys.net/diligence/blog/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/v0.8.20/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
       */
      function sendValue(address payable recipient, uint256 amount) internal {
          if (address(this).balance < amount) {
              revert AddressInsufficientBalance(address(this));
          }
  
          (bool success, ) = recipient.call{value: amount}("");
          if (!success) {
              revert FailedInnerCall();
          }
      }
  
      /**
       * @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 or custom error, it is bubbled
       * up by this function (like regular Solidity function calls). However, if
       * the call reverted with no returned reason, this function reverts with a
       * {FailedInnerCall} error.
       *
       * 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.
       */
      function functionCall(address target, bytes memory data) internal returns (bytes memory) {
          return functionCallWithValue(target, data, 0);
      }
  
      /**
       * @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`.
       */
      function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
          if (address(this).balance < value) {
              revert AddressInsufficientBalance(address(this));
          }
          (bool success, bytes memory returndata) = target.call{value: value}(data);
          return verifyCallResultFromTarget(target, success, returndata);
      }
  
      /**
       * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
       * but performing a static call.
       */
      function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
          (bool success, bytes memory returndata) = target.staticcall(data);
          return verifyCallResultFromTarget(target, success, returndata);
      }
  
      /**
       * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
       * but performing a delegate call.
       */
      function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
          (bool success, bytes memory returndata) = target.delegatecall(data);
          return verifyCallResultFromTarget(target, success, returndata);
      }
  
      /**
       * @dev Tool to verify that a low level call to smart-contract was successful, and reverts if the target
       * was not a contract or bubbling up the revert reason (falling back to {FailedInnerCall}) in case of an
       * unsuccessful call.
       */
      function verifyCallResultFromTarget(
          address target,
          bool success,
          bytes memory returndata
      ) internal view returns (bytes memory) {
          if (!success) {
              _revert(returndata);
          } else {
              // only check if target is a contract if the call was successful and the return data is empty
              // otherwise we already know that it was a contract
              if (returndata.length == 0 && target.code.length == 0) {
                  revert AddressEmptyCode(target);
              }
              return returndata;
          }
      }
  
      /**
       * @dev Tool to verify that a low level call was successful, and reverts if it wasn't, either by bubbling the
       * revert reason or with a default {FailedInnerCall} error.
       */
      function verifyCallResult(bool success, bytes memory returndata) internal pure returns (bytes memory) {
          if (!success) {
              _revert(returndata);
          } else {
              return returndata;
          }
      }
  
      /**
       * @dev Reverts with returndata if present. Otherwise reverts with {FailedInnerCall}.
       */
      function _revert(bytes memory returndata) private pure {
          // 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 FailedInnerCall();
          }
      }
  }
  
  // File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol
  
  
  // OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/utils/SafeERC20.sol)
  
  pragma solidity ^0.8.20;
  
  
  
  
  /**
   * @title SafeERC20
   * @dev Wrappers around ERC20 operations that throw on failure (when the token
   * contract returns false). Tokens that return no value (and instead revert or
   * throw on failure) are also supported, non-reverting calls are assumed to be
   * successful.
   * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
   * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
   */
  library SafeERC20 {
      using Address for address;
  
      /**
       * @dev An operation with an ERC20 token failed.
       */
      error SafeERC20FailedOperation(address token);
  
      /**
       * @dev Indicates a failed `decreaseAllowance` request.
       */
      error SafeERC20FailedDecreaseAllowance(address spender, uint256 currentAllowance, uint256 requestedDecrease);
  
      /**
       * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
       * non-reverting calls are assumed to be successful.
       */
      function safeTransfer(IERC20 token, address to, uint256 value) internal {
          _callOptionalReturn(token, abi.encodeCall(token.transfer, (to, value)));
      }
  
      /**
       * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
       * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
       */
      function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
          _callOptionalReturn(token, abi.encodeCall(token.transferFrom, (from, to, value)));
      }
  
      /**
       * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
       * non-reverting calls are assumed to be successful.
       */
      function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
          uint256 oldAllowance = token.allowance(address(this), spender);
          forceApprove(token, spender, oldAllowance + value);
      }
  
      /**
       * @dev Decrease the calling contract's allowance toward `spender` by `requestedDecrease`. If `token` returns no
       * value, non-reverting calls are assumed to be successful.
       */
      function safeDecreaseAllowance(IERC20 token, address spender, uint256 requestedDecrease) internal {
          unchecked {
              uint256 currentAllowance = token.allowance(address(this), spender);
              if (currentAllowance < requestedDecrease) {
                  revert SafeERC20FailedDecreaseAllowance(spender, currentAllowance, requestedDecrease);
              }
              forceApprove(token, spender, currentAllowance - requestedDecrease);
          }
      }
  
      /**
       * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
       * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
       * to be set to zero before setting it to a non-zero value, such as USDT.
       */
      function forceApprove(IERC20 token, address spender, uint256 value) internal {
          bytes memory approvalCall = abi.encodeCall(token.approve, (spender, value));
  
          if (!_callOptionalReturnBool(token, approvalCall)) {
              _callOptionalReturn(token, abi.encodeCall(token.approve, (spender, 0)));
              _callOptionalReturn(token, approvalCall);
          }
      }
  
      /**
       * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
       * on the return value: the return value is optional (but if data is returned, it must not be false).
       * @param token The token targeted by the call.
       * @param data The call data (encoded using abi.encode or one of its variants).
       */
      function _callOptionalReturn(IERC20 token, bytes memory data) private {
          // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
          // we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
          // the target address contains contract code and also asserts for success in the low-level call.
  
          bytes memory returndata = address(token).functionCall(data);
          if (returndata.length != 0 && !abi.decode(returndata, (bool))) {
              revert SafeERC20FailedOperation(address(token));
          }
      }
  
      /**
       * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
       * on the return value: the return value is optional (but if data is returned, it must not be false).
       * @param token The token targeted by the call.
       * @param data The call data (encoded using abi.encode or one of its variants).
       *
       * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
       */
      function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
          // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
          // we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
          // and not revert is the subcall reverts.
  
          (bool success, bytes memory returndata) = address(token).call(data);
          return success && (returndata.length == 0 || abi.decode(returndata, (bool))) && address(token).code.length > 0;
      }
  }
  
  // File: @openzeppelin/contracts/utils/Context.sol
  
  
  // OpenZeppelin Contracts (last updated v5.0.1) (utils/Context.sol)
  
  pragma solidity ^0.8.20;
  
  /**
   * @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;
      }
  
      function _contextSuffixLength() internal view virtual returns (uint256) {
          return 0;
      }
  }
  
  // File: @openzeppelin/contracts/access/Ownable.sol
  
  
  // OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)
  
  pragma solidity ^0.8.20;
  
  
  /**
   * @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.
   *
   * The initial owner is set to the address provided by the deployer. 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;
  
      /**
       * @dev The caller account is not authorized to perform an operation.
       */
      error OwnableUnauthorizedAccount(address account);
  
      /**
       * @dev The owner is not a valid owner account. (eg. `address(0)`)
       */
      error OwnableInvalidOwner(address owner);
  
      event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
  
      /**
       * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
       */
      constructor(address initialOwner) {
          if (initialOwner == address(0)) {
              revert OwnableInvalidOwner(address(0));
          }
          _transferOwnership(initialOwner);
      }
  
      /**
       * @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 {
          if (owner() != _msgSender()) {
              revert OwnableUnauthorizedAccount(_msgSender());
          }
      }
  
      /**
       * @dev Leaves the contract without owner. It will not be possible to call
       * `onlyOwner` functions. Can only be called by the current owner.
       *
       * NOTE: Renouncing ownership will leave the contract without an owner,
       * thereby disabling 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 {
          if (newOwner == address(0)) {
              revert OwnableInvalidOwner(address(0));
          }
          _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);
      }
  }
  
  // File: @openzeppelin/contracts/security/ReentrancyGuard.sol
  
  
  // OpenZeppelin Contracts (last updated v4.9.0) (security/ReentrancyGuard.sol)
  
  pragma solidity ^0.8.0;
  
  /**
   * @dev Contract module that helps prevent reentrant calls to a function.
   *
   * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
   * available, which can be applied to functions to make sure there are no nested
   * (reentrant) calls to them.
   *
   * Note that because there is a single `nonReentrant` guard, functions marked as
   * `nonReentrant` may not call one another. This can be worked around by making
   * those functions `private`, and then adding `external` `nonReentrant` entry
   * points to them.
   *
   * TIP: If you would like to learn more about reentrancy and alternative ways
   * to protect against it, check out our blog post
   * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
   */
  abstract contract ReentrancyGuard {
      // Booleans are more expensive than uint256 or any type that takes up a full
      // word because each write operation emits an extra SLOAD to first read the
      // slot's contents, replace the bits taken up by the boolean, and then write
      // back. This is the compiler's defense against contract upgrades and
      // pointer aliasing, and it cannot be disabled.
  
      // The values being non-zero value makes deployment a bit more expensive,
      // but in exchange the refund on every call to nonReentrant will be lower in
      // amount. Since refunds are capped to a percentage of the total
      // transaction's gas, it is best to keep them low in cases like this one, to
      // increase the likelihood of the full refund coming into effect.
      uint256 private constant _NOT_ENTERED = 1;
      uint256 private constant _ENTERED = 2;
  
      uint256 private _status;
  
      constructor() {
          _status = _NOT_ENTERED;
      }
  
      /**
       * @dev Prevents a contract from calling itself, directly or indirectly.
       * Calling a `nonReentrant` function from another `nonReentrant`
       * function is not supported. It is possible to prevent this from happening
       * by making the `nonReentrant` function external, and making it call a
       * `private` function that does the actual work.
       */
      modifier nonReentrant() {
          _nonReentrantBefore();
          _;
          _nonReentrantAfter();
      }
  
      function _nonReentrantBefore() private {
          // On the first call to nonReentrant, _status will be _NOT_ENTERED
          require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
  
          // Any calls to nonReentrant after this point will fail
          _status = _ENTERED;
      }
  
      function _nonReentrantAfter() private {
          // By storing the original value once again, a refund is triggered (see
          // https://eips.ethereum.org/EIPS/eip-2200)
          _status = _NOT_ENTERED;
      }
  
      /**
       * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
       * `nonReentrant` function in the call stack.
       */
      function _reentrancyGuardEntered() internal view returns (bool) {
          return _status == _ENTERED;
      }
  }
  
  // File: Staking.sol
  
  
  
  pragma solidity ^0.8.9;
  
  
  
  
  
  
  
  contract MasterChef is Ownable, ReentrancyGuard {
      using SafeMath for uint256;
      using SafeERC20  for IERC20;
  
      // Info of each user.
      struct UserInfo {
          uint256 amount;      
          uint256 rewardDebt; // userRewardPerTokenPaid
          uint256 rewardLockedUp; // rewards
          uint256 timestamp; //stake time
      }
  
      // Info of each pool.
      struct PoolInfo {
          IERC20 lpToken;
          uint256 duration; // total lock period in seconds
          uint256 apy;  // apy in basis point
          uint256 lastRewardTime;  // Last block time that reward distribution occurs.
          uint256 accTokenPerShare;   // Accumulated reward per share, rewardPerTokenStored
          uint256 totalSupply; // total supply in this pool
      }
  
      // The Reward TOKEN!
      IERC20 public rewardToken;
      
      // rewards durations
      uint256 public rewardDuration = 365 days;
  
      address private claimingContract;
      
      // Info of each pool.
      PoolInfo[] public poolInfo;
  
      // mapping of stakeholder address by pool id
      mapping(uint256 => address[]) public stakeHolders;
  
      // Info of each user that stakes LP tokens.
      mapping(uint256 => mapping(address => UserInfo)) public userInfo;
  
      // Total locked up rewards
      uint256 public totalLockedUpRewards;
  
      uint256 public totalClaimedRewards;
  
      event Deposit(address indexed user, uint256 indexed pid, uint256 amount, uint256 indexed timestamp);
      event Withdraw(address indexed user, uint256 indexed pid, uint256 amount, uint256 indexed timestamp);
      event Harvest(address indexed user, uint256 amount, uint256 indexed timestamp);
  
      constructor(
          address _rewardToken
      ) Ownable(msg.sender)  {
          rewardToken = IERC20(_rewardToken);
      }
  
      modifier onlyClaimingContract {
          require(msg.sender == claimingContract);
          _;
      }
  
      function getClaimingContract() external view returns (address) {
          return claimingContract;
      }
  
      function setClaimingContract(address _claimingContract) external onlyOwner {
          claimingContract = _claimingContract;
      }
  
      function poolLength() external view returns (uint256) {
          return poolInfo.length;
      }
  
      function stakeHoldersLength(uint256 _pid) external view returns (uint256) {
          return stakeHolders[_pid].length;
      }
  
      function initializePools(IERC20 _lptoken1) external onlyOwner {
          add(_lptoken1, 86400*30, 800, true);
          add(_lptoken1, 86400*30*3, 2000, true);
          add(_lptoken1, 86400*30*6, 3500, true);
          add(_lptoken1, 86400*30*9, 4000, true);
          add(_lptoken1, 86400*30*12, 5000, true);    
  
          add(_lptoken1, 86400*30, 1200, true);
          add(_lptoken1, 86400*30*3, 2500, true);
          add(_lptoken1, 86400*30*6, 4500, true);
          add(_lptoken1, 86400*30*9, 5500, true);
          add(_lptoken1, 86400*30*12, 7000, true);     
      }
  
      function add(IERC20 _lptoken, uint256 _duration, uint256 _apy, bool _withUpdate) public onlyOwner {
          
          if (_withUpdate) {
              massUpdatePools();
          }
          poolInfo.push(PoolInfo({
          lpToken: _lptoken,
          duration: _duration,
          apy: _apy,
          lastRewardTime: block.timestamp,
          accTokenPerShare: 0,
          totalSupply:0
          }));
      }
  
      function set(uint256 _pid, uint256 _duration, uint256 _apy, bool _withUpdate) public onlyOwner {
          if (_withUpdate) {
              massUpdatePools();
          }
          poolInfo[_pid].duration = _duration;
          poolInfo[_pid].apy = _apy;
      }
  
      // Return reward multiplier over the given _from to _to block.
      function getMultiplier(uint256 _from, uint256 _to) public pure returns (uint256) {
          return _to.sub(_from);
      }
  
      // View function to see pending 888 on frontend.
      function pendingToken(uint256 _pid, address _user) external view returns (uint256) {
          PoolInfo storage pool = poolInfo[_pid];
          UserInfo storage user = userInfo[_pid][_user];
          uint256 accTokenPerShare = pool.accTokenPerShare;
          uint256 lpSupply = pool.totalSupply;
          if (block.timestamp > pool.lastRewardTime && lpSupply != 0) {
              uint256 multiplier = getMultiplier(pool.lastRewardTime, block.timestamp);
              // calculate Rewards (totalSupply x apy / 10000) / 1year
              uint256 tokenReward = lpSupply.mul(pool.apy).mul(multiplier).div(10000).div(rewardDuration);
              accTokenPerShare = accTokenPerShare.add(tokenReward.mul(1e18).div(lpSupply)); // tokenReward.mul(1e12).div(lpSupply)
          }
          uint256 pending = user.amount.mul(accTokenPerShare).div(1e18).sub(user.rewardDebt);
          return pending.add(user.rewardLockedUp);
      }
  
      // Update reward variables for all pools. Be careful of gas spending!
      function massUpdatePools() public {
          uint256 length = poolInfo.length;
          for (uint256 pid = 0; pid < length; ++pid) {
              updatePool(pid);
          }
      }
  
      // Update reward variables of the given pool to be up-to-date.
      function updatePool(uint256 _pid) public {
          PoolInfo storage pool = poolInfo[_pid];
          if (block.timestamp <= pool.lastRewardTime) {
              return;
          }
          uint256 lpSupply = pool.totalSupply;
          if (lpSupply == 0) {
              pool.lastRewardTime = block.timestamp;
              return;
          }
          uint256 multiplier = getMultiplier(pool.lastRewardTime, block.timestamp);
          uint256 tokenReward = lpSupply.mul(pool.apy).mul(multiplier).div(10000).div(rewardDuration);
          
          pool.accTokenPerShare = pool.accTokenPerShare.add(tokenReward.mul(1e18).div(lpSupply));
          pool.lastRewardTime = block.timestamp;
      }
  
  
      // Deposit LP tokens to MasterChef for 888 allocation.
      function deposit(uint256 _pid, uint256 _amount) public nonReentrant { 
          PoolInfo storage pool = poolInfo[_pid];
          UserInfo storage user = userInfo[_pid][msg.sender];
          updatePool(_pid);
          LockupPendingToken(_pid, msg.sender);
          if (_amount > 0) {
              if( user.amount == 0 ) {
                  addStakeholder(msg.sender, _pid);
                  user.timestamp = block.timestamp;
              }
              pool.lpToken.safeTransferFrom(address(msg.sender), address(this), _amount);
              user.amount = user.amount.add(_amount);
              pool.totalSupply = pool.totalSupply.add(_amount);
              emit Deposit(msg.sender, _pid, user.amount, block.timestamp);
          }
          user.rewardDebt = user.amount.mul(pool.accTokenPerShare).div(1e18);
      }
  
      function deposit(uint256 _pid, uint256 _amount, address _owner, address _sender) external onlyClaimingContract nonReentrant { 
          PoolInfo storage pool = poolInfo[_pid];
          UserInfo storage user = userInfo[_pid][_sender];
          updatePool(_pid);
          LockupPendingToken(_pid, _sender);
          if (_amount > 0) {
              if( user.amount == 0 ) {
                  addStakeholder(_sender, _pid);
                  user.timestamp = block.timestamp;
              }
              pool.lpToken.safeTransferFrom(address(_owner), address(this), _amount);
              user.amount = user.amount.add(_amount);
              pool.totalSupply = pool.totalSupply.add(_amount);
              emit Deposit(_sender, _pid, user.amount, block.timestamp);
          }
          user.rewardDebt = user.amount.mul(pool.accTokenPerShare).div(1e18);
      }
  
  
      // Withdraw LP tokens from MasterChef.
      function withdraw(uint256 _pid, uint256 _amount) internal nonReentrant {
          PoolInfo storage pool = poolInfo[_pid];
          UserInfo storage user = userInfo[_pid][msg.sender];
          require(user.amount >= _amount, "withdraw: not good");
          require(block.timestamp >= user.timestamp.add(pool.duration), "Stake period is not expired..");
          updatePool(_pid);
          LockupPendingToken(_pid, msg.sender);
          if (_amount > 0) {
              user.amount = user.amount.sub(_amount);
              pool.totalSupply = pool.totalSupply.sub(_amount);
              pool.lpToken.safeTransfer(address(msg.sender), _amount);
          }
          if ( user.amount == 0 ) {
              removeStakeholder(msg.sender, _pid);
          }
  
          user.rewardDebt = user.amount.mul(pool.accTokenPerShare).div(1e18);
          emit Withdraw(msg.sender, _pid, _amount, block.timestamp);
      }
  
      // Pay or lockup pending 888s.
      function LockupPendingToken(uint256 _pid, address _msgSender) internal {
          PoolInfo storage pool = poolInfo[_pid];
          UserInfo storage user = userInfo[_pid][_msgSender];
  
          uint256 pending = user.amount.mul(pool.accTokenPerShare).div(1e18).sub(user.rewardDebt); 
  
          user.rewardLockedUp = user.rewardLockedUp.add(pending);
          totalLockedUpRewards = totalLockedUpRewards.add(pending);
          
      }
  
      function getRewards(uint256 _pid) public nonReentrant {
          PoolInfo storage pool = poolInfo[_pid];
          UserInfo storage user = userInfo[_pid][msg.sender];
          require(block.timestamp >= user.timestamp.add(pool.duration + 7 days), "Stake period is not expired..");
          updatePool(_pid);
          LockupPendingToken(_pid, msg.sender);
  
          uint256 pending = user.amount.mul(pool.accTokenPerShare).div(1e18).sub(user.rewardDebt);
  
          if (pending > 0 || user.rewardLockedUp > 0) {
              uint256 totalRewards = pending.add(user.rewardLockedUp);
              totalClaimedRewards = totalClaimedRewards.add(totalRewards);    
              // reset lockup
              totalLockedUpRewards = totalLockedUpRewards.sub(user.rewardLockedUp);
              user.rewardLockedUp = 0;
              user.rewardDebt = user.amount.mul(pool.accTokenPerShare).div(1e18);
              // send rewards
              rewardToken.safeTransferFrom(owner(), msg.sender, totalRewards);
              
              emit Harvest(msg.sender, totalRewards, block.timestamp);
          }
      }
  
      function exit(uint256 _pid, uint256 _amount) external {
          withdraw(_pid, _amount);
      }
  
      function remainingRewardTokens() external view returns (uint256) {
          return Math.min(rewardToken.balanceOf(owner()), rewardToken.allowance(owner(), address(this)));
      }
  
      function withdrawAllowed(uint256 _pid, address _user) public view returns (bool) {
          PoolInfo storage pool = poolInfo[_pid];
          UserInfo storage user = userInfo[_pid][_user];
  
          return block.timestamp >= user.timestamp.add(pool.duration);
      }
  
      function isStakeholder(address _address, uint256 _pid)
          internal
          view
          returns(bool, uint256)
      {
          for (uint256 s = 0; s < stakeHolders[_pid].length; s += 1){
              if (_address == stakeHolders[_pid][s]) return (true, s);
          }
          return (false, 0);
      }
  
     
      function addStakeholder(address _stakeholder, uint256 _pid)
          internal
      {
          (bool _isStakeholder, ) = isStakeholder(_stakeholder, _pid);
          if(!_isStakeholder) stakeHolders[_pid].push(_stakeholder);
      }
  
      
      function removeStakeholder(address _stakeholder, uint _pid)
          internal
      {
          (bool _isStakeholder, uint256 s) = isStakeholder(_stakeholder, _pid);
          if(_isStakeholder){
              stakeHolders[_pid][s] = stakeHolders[_pid][stakeHolders[_pid].length - 1];
              stakeHolders[_pid].pop();
          } 
      }
   
  }