// SPDX-License-Identifier: BUSL-1.1
// For further clarification please see https://license.premia.legal

pragma solidity ^0.8.0;

import {OwnableInternal, OwnableStorage} from "@solidstate/contracts/access/OwnableInternal.sol";
import {EnumerableSet} from "@solidstate/contracts/utils/EnumerableSet.sol";
import {ABDKMath64x64} from "abdk-libraries-solidity/ABDKMath64x64.sol";

import {OptionMath} from "../libraries/OptionMath.sol";
import {VolatilitySurfaceOracleStorage} from "./VolatilitySurfaceOracleStorage.sol";
import {IVolatilitySurfaceOracle} from "./IVolatilitySurfaceOracle.sol";

/**
 * @title Premia volatility surface oracle contract
 */
contract VolatilitySurfaceOracle is IVolatilitySurfaceOracle, OwnableInternal {
    using VolatilitySurfaceOracleStorage for VolatilitySurfaceOracleStorage.Layout;
    using EnumerableSet for EnumerableSet.AddressSet;
    using ABDKMath64x64 for int128;

    uint256 private constant DECIMALS = 12;

    event UpdateParameters(
        address indexed base,
        address indexed underlying,
        bytes32 params // Parameters for volatility model
    );

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function formatParams(int256[5] memory params)
        external
        pure
        returns (bytes32 result)
    {
        return VolatilitySurfaceOracleStorage.formatParams(params);
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function parseParams(bytes32 input)
        external
        pure
        returns (int256[] memory params)
    {
        return VolatilitySurfaceOracleStorage.parseParams(input);
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function getWhitelistedRelayers() external view returns (address[] memory) {
        VolatilitySurfaceOracleStorage.Layout
            storage l = VolatilitySurfaceOracleStorage.layout();

        uint256 length = l.whitelistedRelayers.length();
        address[] memory result = new address[](length);

        for (uint256 i = 0; i < length; i++) {
            result[i] = l.whitelistedRelayers.at(i);
        }

        return result;
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function getParams(address base, address underlying)
        external
        view
        returns (VolatilitySurfaceOracleStorage.Update memory)
    {
        VolatilitySurfaceOracleStorage.Layout
            storage l = VolatilitySurfaceOracleStorage.layout();
        return l.parameters[base][underlying];
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function getParamsUnpacked(address base, address underlying)
        external
        view
        returns (int256[] memory)
    {
        VolatilitySurfaceOracleStorage.Layout
            storage l = VolatilitySurfaceOracleStorage.layout();
        bytes32 packed = l.getParams(base, underlying);
        return VolatilitySurfaceOracleStorage.parseParams(packed);
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function getTimeToMaturity64x64(uint64 maturity)
        external
        view
        returns (int128)
    {
        return ABDKMath64x64.divu(maturity - block.timestamp, 365 days);
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function getAnnualizedVolatility64x64(
        address base,
        address underlying,
        int128 spot64x64,
        int128 strike64x64,
        int128 timeToMaturity64x64
    ) external view returns (int128) {
        return
            _getAnnualizedVolatility64x64(
                base,
                underlying,
                spot64x64,
                strike64x64,
                timeToMaturity64x64
            );
    }

    /**
     * @notice see getAnnualizedVolatility64x64(address,address,int128,int128,int128)
     * @dev deprecated - will be removed once PoolInternal call is updated
     */
    function getAnnualizedVolatility64x64(
        address base,
        address underlying,
        int128 spot64x64,
        int128 strike64x64,
        int128 timeToMaturity64x64,
        bool
    ) external view returns (int128) {
        return
            _getAnnualizedVolatility64x64(
                base,
                underlying,
                spot64x64,
                strike64x64,
                timeToMaturity64x64
            );
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function getBlackScholesPrice64x64(
        address base,
        address underlying,
        int128 spot64x64,
        int128 strike64x64,
        int128 timeToMaturity64x64,
        bool isCall
    ) external view returns (int128) {
        return
            _getBlackScholesPrice64x64(
                base,
                underlying,
                spot64x64,
                strike64x64,
                timeToMaturity64x64,
                isCall
            );
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function getBlackScholesPrice(
        address base,
        address underlying,
        int128 spot64x64,
        int128 strike64x64,
        int128 timeToMaturity64x64,
        bool isCall
    ) external view returns (uint256) {
        return
            _getBlackScholesPrice64x64(
                base,
                underlying,
                spot64x64,
                strike64x64,
                timeToMaturity64x64,
                isCall
            ).mulu(10**18);
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function addWhitelistedRelayers(address[] memory accounts)
        external
        onlyOwner
    {
        VolatilitySurfaceOracleStorage.Layout
            storage l = VolatilitySurfaceOracleStorage.layout();

        for (uint256 i = 0; i < accounts.length; i++) {
            l.whitelistedRelayers.add(accounts[i]);
        }
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function removeWhitelistedRelayers(address[] memory accounts)
        external
        onlyOwner
    {
        VolatilitySurfaceOracleStorage.Layout
            storage l = VolatilitySurfaceOracleStorage.layout();

        for (uint256 i = 0; i < accounts.length; i++) {
            l.whitelistedRelayers.remove(accounts[i]);
        }
    }

    /**
     * @inheritdoc IVolatilitySurfaceOracle
     */
    function updateParams(
        address[] memory base,
        address[] memory underlying,
        bytes32[] memory parameters
    ) external {
        uint256 length = base.length;
        require(
            length == underlying.length && length == parameters.length,
            "Wrong array length"
        );

        VolatilitySurfaceOracleStorage.Layout
            storage l = VolatilitySurfaceOracleStorage.layout();

        require(
            l.whitelistedRelayers.contains(msg.sender),
            "Relayer not whitelisted"
        );

        for (uint256 i = 0; i < length; i++) {
            l.parameters[base[i]][
                underlying[i]
            ] = VolatilitySurfaceOracleStorage.Update({
                updatedAt: block.timestamp,
                params: parameters[i]
            });

            emit UpdateParameters(base[i], underlying[i], parameters[i]);
        }
    }

    /**
     * @notice convert decimal parameter to 64x64 fixed point representation
     * @param value parameter to convert
     * @return 64x64 fixed point representation of parameter
     */
    function _toParameter64x64(int256 value) private pure returns (int128) {
        return ABDKMath64x64.divi(value, int256(10**DECIMALS));
    }

    /**
     * @notice calculate the annualized volatility for given set of parameters
     * @param base The base token of the pair
     * @param underlying The underlying token of the pair
     * @param spot64x64 64x64 fixed point representation of spot price
     * @param strike64x64 64x64 fixed point representation of strike price
     * @param timeToMaturity64x64 64x64 fixed point representation of time to maturity (denominated in years)
     * @return 64x64 fixed point representation of annualized implied volatility, where 1 is defined as 100%
     */
    function _getAnnualizedVolatility64x64(
        address base,
        address underlying,
        int128 spot64x64,
        int128 strike64x64,
        int128 timeToMaturity64x64
    ) private view returns (int128) {
        VolatilitySurfaceOracleStorage.Layout
            storage l = VolatilitySurfaceOracleStorage.layout();

        int256[] memory params = VolatilitySurfaceOracleStorage.parseParams(
            l.getParams(base, underlying)
        );

        // Time adjusted log moneyness
        int128 M64x64 = spot64x64.div(strike64x64).ln().div(
            timeToMaturity64x64.sqrt()
        );

        return
            _toParameter64x64(params[0]) +
            _toParameter64x64(params[1]).mul(M64x64) +
            _toParameter64x64(params[2]).mul(M64x64.mul(M64x64)) +
            _toParameter64x64(params[3]).mul(timeToMaturity64x64) +
            _toParameter64x64(params[4]).mul(M64x64).mul(timeToMaturity64x64);
    }

    /**
     * @notice calculate the price of an option using the Black-Scholes model
     * @param base The base token of the pair
     * @param underlying The underlying token of the pair
     * @param spot64x64 Spot price, as a 64x64 fixed point representation
     * @param strike64x64 Strike, as a64x64 fixed point representation
     * @param timeToMaturity64x64 64x64 fixed point representation of time to maturity (denominated in years)
     * @param isCall Whether it is for call or put
     * @return 64x64 fixed point representation of the Black Scholes price
     */
    function _getBlackScholesPrice64x64(
        address base,
        address underlying,
        int128 spot64x64,
        int128 strike64x64,
        int128 timeToMaturity64x64,
        bool isCall
    ) private view returns (int128) {
        int128 annualizedVol = _getAnnualizedVolatility64x64(
            base,
            underlying,
            spot64x64,
            strike64x64,
            timeToMaturity64x64
        );
        int128 annualizedVar = annualizedVol.mul(annualizedVol);

        return
            OptionMath._blackScholesPrice(
                annualizedVar,
                strike64x64,
                spot64x64,
                timeToMaturity64x64,
                isCall
            );
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import { OwnableStorage } from './OwnableStorage.sol';

abstract contract OwnableInternal {
    using OwnableStorage for OwnableStorage.Layout;

    modifier onlyOwner() {
        require(
            msg.sender == OwnableStorage.layout().owner,
            'Ownable: sender must be owner'
        );
        _;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @title Set implementation with enumeration functions
 * @dev derived from https://github.com/OpenZeppelin/openzeppelin-contracts (MIT license)
 */
library EnumerableSet {
    struct Set {
        bytes32[] _values;
        // 1-indexed to allow 0 to signify nonexistence
        mapping(bytes32 => uint256) _indexes;
    }

    struct Bytes32Set {
        Set _inner;
    }

    struct AddressSet {
        Set _inner;
    }

    struct UintSet {
        Set _inner;
    }

    function at(Bytes32Set storage set, uint256 index)
        internal
        view
        returns (bytes32)
    {
        return _at(set._inner, index);
    }

    function at(AddressSet storage set, uint256 index)
        internal
        view
        returns (address)
    {
        return address(uint160(uint256(_at(set._inner, index))));
    }

    function at(UintSet storage set, uint256 index)
        internal
        view
        returns (uint256)
    {
        return uint256(_at(set._inner, index));
    }

    function contains(Bytes32Set storage set, bytes32 value)
        internal
        view
        returns (bool)
    {
        return _contains(set._inner, value);
    }

    function contains(AddressSet storage set, address value)
        internal
        view
        returns (bool)
    {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    function contains(UintSet storage set, uint256 value)
        internal
        view
        returns (bool)
    {
        return _contains(set._inner, bytes32(value));
    }

    function indexOf(Bytes32Set storage set, bytes32 value)
        internal
        view
        returns (uint256)
    {
        return _indexOf(set._inner, value);
    }

    function indexOf(AddressSet storage set, address value)
        internal
        view
        returns (uint256)
    {
        return _indexOf(set._inner, bytes32(uint256(uint160(value))));
    }

    function indexOf(UintSet storage set, uint256 value)
        internal
        view
        returns (uint256)
    {
        return _indexOf(set._inner, bytes32(value));
    }

    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

    function add(Bytes32Set storage set, bytes32 value)
        internal
        returns (bool)
    {
        return _add(set._inner, value);
    }

    function add(AddressSet storage set, address value)
        internal
        returns (bool)
    {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    function remove(Bytes32Set storage set, bytes32 value)
        internal
        returns (bool)
    {
        return _remove(set._inner, value);
    }

    function remove(AddressSet storage set, address value)
        internal
        returns (bool)
    {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    function remove(UintSet storage set, uint256 value)
        internal
        returns (bool)
    {
        return _remove(set._inner, bytes32(value));
    }

    function _at(Set storage set, uint256 index)
        private
        view
        returns (bytes32)
    {
        require(
            set._values.length > index,
            'EnumerableSet: index out of bounds'
        );
        return set._values[index];
    }

    function _contains(Set storage set, bytes32 value)
        private
        view
        returns (bool)
    {
        return set._indexes[value] != 0;
    }

    function _indexOf(Set storage set, bytes32 value)
        private
        view
        returns (uint256)
    {
        unchecked {
            return set._indexes[value] - 1;
        }
    }

    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    function _remove(Set storage set, bytes32 value) private returns (bool) {
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) {
            unchecked {
                bytes32 last = set._values[set._values.length - 1];

                // move last value to now-vacant index

                set._values[valueIndex - 1] = last;
                set._indexes[last] = valueIndex;
            }
            // clear last index

            set._values.pop();
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }
}

// SPDX-License-Identifier: BSD-4-Clause
/*
 * ABDK Math 64.64 Smart Contract Library.  Copyright © 2019 by ABDK Consulting.
 * Author: Mikhail Vladimirov <[email protected]>
 */
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: BUSL-1.1
// For further clarification please see https://license.premia.legal

pragma solidity ^0.8.0;

import {ABDKMath64x64} from "abdk-libraries-solidity/ABDKMath64x64.sol";

library OptionMath {
    using ABDKMath64x64 for int128;

    struct QuoteArgs {
        int128 varianceAnnualized64x64; // 64x64 fixed point representation of annualized variance
        int128 strike64x64; // 64x64 fixed point representation of strike price
        int128 spot64x64; // 64x64 fixed point representation of spot price
        int128 timeToMaturity64x64; // 64x64 fixed point representation of duration of option contract (in years)
        int128 oldCLevel64x64; // 64x64 fixed point representation of C-Level of Pool before purchase
        int128 oldPoolState; // 64x64 fixed point representation of current state of the pool
        int128 newPoolState; // 64x64 fixed point representation of state of the pool after trade
        int128 steepness64x64; // 64x64 fixed point representation of Pool state delta multiplier
        int128 minAPY64x64; // 64x64 fixed point representation of minimum APY for capital locked up to underwrite options
        bool isCall; // whether to price "call" or "put" option
    }

    struct CalculateCLevelDecayArgs {
        int128 timeIntervalsElapsed64x64; // 64x64 fixed point representation of quantity of discrete arbitrary intervals elapsed since last update
        int128 oldCLevel64x64; // 64x64 fixed point representation of C-Level prior to accounting for decay
        int128 utilization64x64; // 64x64 fixed point representation of pool capital utilization rate
        int128 utilizationLowerBound64x64;
        int128 utilizationUpperBound64x64;
        int128 cLevelLowerBound64x64;
        int128 cLevelUpperBound64x64;
        int128 cConvergenceULowerBound64x64;
        int128 cConvergenceUUpperBound64x64;
    }

    // 64x64 fixed point integer constants
    int128 internal constant ONE_64x64 = 0x10000000000000000;
    int128 internal constant THREE_64x64 = 0x30000000000000000;

    // 64x64 fixed point constants used in Choudhury’s approximation of the Black-Scholes CDF
    int128 private constant CDF_CONST_0 = 0x09109f285df452394; // 2260 / 3989
    int128 private constant CDF_CONST_1 = 0x19abac0ea1da65036; // 6400 / 3989
    int128 private constant CDF_CONST_2 = 0x0d3c84b78b749bd6b; // 3300 / 3989

    /**
     * @notice recalculate C-Level based on change in liquidity
     * @param initialCLevel64x64 64x64 fixed point representation of C-Level of Pool before update
     * @param oldPoolState64x64 64x64 fixed point representation of liquidity in pool before update
     * @param newPoolState64x64 64x64 fixed point representation of liquidity in pool after update
     * @param steepness64x64 64x64 fixed point representation of steepness coefficient
     * @return 64x64 fixed point representation of new C-Level
     */
    function calculateCLevel(
        int128 initialCLevel64x64,
        int128 oldPoolState64x64,
        int128 newPoolState64x64,
        int128 steepness64x64
    ) external pure returns (int128) {
        return
            newPoolState64x64
                .sub(oldPoolState64x64)
                .div(
                    oldPoolState64x64 > newPoolState64x64
                        ? oldPoolState64x64
                        : newPoolState64x64
                )
                .mul(steepness64x64)
                .neg()
                .exp()
                .mul(initialCLevel64x64);
    }

    /**
     * @notice calculate the price of an option using the Premia Finance model
     * @param args arguments of quotePrice
     * @return premiaPrice64x64 64x64 fixed point representation of Premia option price
     * @return cLevel64x64 64x64 fixed point representation of C-Level of Pool after purchase
     */
    function quotePrice(QuoteArgs memory args)
        external
        pure
        returns (
            int128 premiaPrice64x64,
            int128 cLevel64x64,
            int128 slippageCoefficient64x64
        )
    {
        int128 deltaPoolState64x64 = args
            .newPoolState
            .sub(args.oldPoolState)
            .div(args.oldPoolState)
            .mul(args.steepness64x64);
        int128 tradingDelta64x64 = deltaPoolState64x64.neg().exp();

        int128 blackScholesPrice64x64 = _blackScholesPrice(
            args.varianceAnnualized64x64,
            args.strike64x64,
            args.spot64x64,
            args.timeToMaturity64x64,
            args.isCall
        );

        cLevel64x64 = tradingDelta64x64.mul(args.oldCLevel64x64);
        slippageCoefficient64x64 = ONE_64x64.sub(tradingDelta64x64).div(
            deltaPoolState64x64
        );

        premiaPrice64x64 = blackScholesPrice64x64.mul(cLevel64x64).mul(
            slippageCoefficient64x64
        );

        int128 intrinsicValue64x64;

        if (args.isCall && args.strike64x64 < args.spot64x64) {
            intrinsicValue64x64 = args.spot64x64.sub(args.strike64x64);
        } else if (!args.isCall && args.strike64x64 > args.spot64x64) {
            intrinsicValue64x64 = args.strike64x64.sub(args.spot64x64);
        }

        int128 collateralValue64x64 = args.isCall
            ? args.spot64x64
            : args.strike64x64;

        int128 minPrice64x64 = intrinsicValue64x64.add(
            collateralValue64x64.mul(args.minAPY64x64).mul(
                args.timeToMaturity64x64
            )
        );

        if (minPrice64x64 > premiaPrice64x64) {
            premiaPrice64x64 = minPrice64x64;
        }
    }

    /**
     * @notice calculate the decay of C-Level based on heat diffusion function
     * @param args structured CalculateCLevelDecayArgs
     * @return cLevelDecayed64x64 C-Level after accounting for decay
     */
    function calculateCLevelDecay(CalculateCLevelDecayArgs memory args)
        external
        pure
        returns (int128 cLevelDecayed64x64)
    {
        int128 convFHighU64x64 = (args.utilization64x64 >=
            args.utilizationUpperBound64x64 &&
            args.oldCLevel64x64 <= args.cLevelLowerBound64x64)
            ? ONE_64x64
            : int128(0);

        int128 convFLowU64x64 = (args.utilization64x64 <=
            args.utilizationLowerBound64x64 &&
            args.oldCLevel64x64 >= args.cLevelUpperBound64x64)
            ? ONE_64x64
            : int128(0);

        cLevelDecayed64x64 = args
            .oldCLevel64x64
            .sub(args.cConvergenceULowerBound64x64.mul(convFLowU64x64))
            .sub(args.cConvergenceUUpperBound64x64.mul(convFHighU64x64))
            .mul(
                convFLowU64x64
                    .mul(ONE_64x64.sub(args.utilization64x64))
                    .add(convFHighU64x64.mul(args.utilization64x64))
                    .mul(args.timeIntervalsElapsed64x64)
                    .neg()
                    .exp()
            )
            .add(
                args.cConvergenceULowerBound64x64.mul(convFLowU64x64).add(
                    args.cConvergenceUUpperBound64x64.mul(convFHighU64x64)
                )
            );
    }

    /**
     * @notice calculate the exponential decay coefficient for a given interval
     * @param oldTimestamp timestamp of previous update
     * @param newTimestamp current timestamp
     * @return 64x64 fixed point representation of exponential decay coefficient
     */
    function _decay(uint256 oldTimestamp, uint256 newTimestamp)
        internal
        pure
        returns (int128)
    {
        return
            ONE_64x64.sub(
                (-ABDKMath64x64.divu(newTimestamp - oldTimestamp, 7 days)).exp()
            );
    }

    /**
     * @notice calculate Choudhury’s approximation of the Black-Scholes CDF
     * @param input64x64 64x64 fixed point representation of random variable
     * @return 64x64 fixed point representation of the approximated CDF of x
     */
    function _N(int128 input64x64) internal pure returns (int128) {
        // squaring via mul is cheaper than via pow
        int128 inputSquared64x64 = input64x64.mul(input64x64);

        int128 value64x64 = (-inputSquared64x64 >> 1).exp().div(
            CDF_CONST_0.add(CDF_CONST_1.mul(input64x64.abs())).add(
                CDF_CONST_2.mul(inputSquared64x64.add(THREE_64x64).sqrt())
            )
        );

        return input64x64 > 0 ? ONE_64x64.sub(value64x64) : value64x64;
    }

    /**
     * @notice calculate the price of an option using the Black-Scholes model
     * @param varianceAnnualized64x64 64x64 fixed point representation of annualized variance
     * @param strike64x64 64x64 fixed point representation of strike price
     * @param spot64x64 64x64 fixed point representation of spot price
     * @param timeToMaturity64x64 64x64 fixed point representation of duration of option contract (in years)
     * @param isCall whether to price "call" or "put" option
     * @return 64x64 fixed point representation of Black-Scholes option price
     */
    function _blackScholesPrice(
        int128 varianceAnnualized64x64,
        int128 strike64x64,
        int128 spot64x64,
        int128 timeToMaturity64x64,
        bool isCall
    ) internal pure returns (int128) {
        int128 cumulativeVariance64x64 = timeToMaturity64x64.mul(
            varianceAnnualized64x64
        );
        int128 cumulativeVarianceSqrt64x64 = cumulativeVariance64x64.sqrt();

        int128 d1_64x64 = spot64x64
            .div(strike64x64)
            .ln()
            .add(cumulativeVariance64x64 >> 1)
            .div(cumulativeVarianceSqrt64x64);
        int128 d2_64x64 = d1_64x64.sub(cumulativeVarianceSqrt64x64);

        if (isCall) {
            return
                spot64x64.mul(_N(d1_64x64)).sub(strike64x64.mul(_N(d2_64x64)));
        } else {
            return
                -spot64x64.mul(_N(-d1_64x64)).sub(
                    strike64x64.mul(_N(-d2_64x64))
                );
        }
    }
}

// SPDX-License-Identifier: BUSL-1.1

pragma solidity ^0.8.0;

import {EnumerableSet} from "@solidstate/contracts/utils/EnumerableSet.sol";

library VolatilitySurfaceOracleStorage {
    bytes32 internal constant STORAGE_SLOT =
        keccak256("premia.contracts.storage.VolatilitySurfaceOracle");

    uint256 internal constant PARAM_BITS = 51;
    uint256 internal constant PARAM_BITS_MINUS_ONE = 50;
    uint256 internal constant PARAM_AMOUNT = 5;
    // START_BIT = PARAM_BITS * (PARAM_AMOUNT - 1)
    uint256 internal constant START_BIT = 204;

    struct Update {
        uint256 updatedAt;
        bytes32 params;
    }

    struct Layout {
        // Base token -> Underlying token -> Update
        mapping(address => mapping(address => Update)) parameters;
        // Relayer addresses which can be trusted to provide accurate option trades
        EnumerableSet.AddressSet whitelistedRelayers;
    }

    function layout() internal pure returns (Layout storage l) {
        bytes32 slot = STORAGE_SLOT;
        assembly {
            l.slot := slot
        }
    }

    function getParams(
        Layout storage l,
        address base,
        address underlying
    ) internal view returns (bytes32) {
        return l.parameters[base][underlying].params;
    }

    function parseParams(bytes32 input)
        internal
        pure
        returns (int256[] memory params)
    {
        params = new int256[](PARAM_AMOUNT);

        // Value to add to negative numbers to cast them to int256
        int256 toAdd = (int256(-1) >> PARAM_BITS) << PARAM_BITS;

        assembly {
            let i := 0
            // Value equal to -1

            let mid := shl(PARAM_BITS_MINUS_ONE, 1)

            for {

            } lt(i, PARAM_AMOUNT) {

            } {
                let offset := sub(START_BIT, mul(PARAM_BITS, i))
                let param := shr(
                    offset,
                    sub(
                        input,
                        shl(
                            add(offset, PARAM_BITS),
                            shr(add(offset, PARAM_BITS), input)
                        )
                    )
                )

                // Check if value is a negative number and needs casting
                if or(eq(param, mid), gt(param, mid)) {
                    param := add(param, toAdd)
                }

                // Store result in the params array
                mstore(add(params, add(0x20, mul(0x20, i))), param)

                i := add(i, 1)
            }
        }
    }

    function formatParams(int256[5] memory params)
        internal
        pure
        returns (bytes32 result)
    {
        int256 max = int256(1 << PARAM_BITS_MINUS_ONE);

        unchecked {
            for (uint256 i = 0; i < PARAM_AMOUNT; i++) {
                require(params[i] < max && params[i] > -max, "Out of bounds");
            }
        }

        assembly {
            let i := 0

            for {

            } lt(i, PARAM_AMOUNT) {

            } {
                let offset := sub(START_BIT, mul(PARAM_BITS, i))
                let param := mload(add(params, mul(0x20, i)))

                result := add(
                    result,
                    shl(
                        offset,
                        sub(param, shl(PARAM_BITS, shr(PARAM_BITS, param)))
                    )
                )

                i := add(i, 1)
            }
        }
    }
}

// SPDX-License-Identifier: LGPL-3.0-or-later

pragma solidity ^0.8.0;

import {VolatilitySurfaceOracleStorage} from "./VolatilitySurfaceOracleStorage.sol";

interface IVolatilitySurfaceOracle {
    /**
     * @notice Pack IV model parameters into a single bytes32
     * @dev This function is used to pack the parameters into a single variable, which is then used as input in `update`
     * @param params Parameters of IV model to pack
     * @return result The packed parameters of IV model
     */
    function formatParams(int256[5] memory params)
        external
        pure
        returns (bytes32 result);

    /**
     * @notice Unpack IV model parameters from a bytes32
     * @param input Packed IV model parameters to unpack
     * @return params The unpacked parameters of the IV model
     */
    function parseParams(bytes32 input)
        external
        pure
        returns (int256[] memory params);

    /**
     * @notice Get the list of whitelisted relayers
     * @return The list of whitelisted relayers
     */
    function getWhitelistedRelayers() external view returns (address[] memory);

    /**
     * @notice Get the IV model parameters of a token pair
     * @param base The base token of the pair
     * @param underlying The underlying token of the pair
     * @return The IV model parameters
     */
    function getParams(address base, address underlying)
        external
        view
        returns (VolatilitySurfaceOracleStorage.Update memory);

    /**
     * @notice Get unpacked IV model parameters
     * @param base The base token of the pair
     * @param underlying The underlying token of the pair
     * @return The unpacked IV model parameters
     */
    function getParamsUnpacked(address base, address underlying)
        external
        view
        returns (int256[] memory);

    /**
     * @notice Get time to maturity in years, as a 64x64 fixed point representation
     * @param maturity Maturity timestamp
     * @return Time to maturity (in years), as a 64x64 fixed point representation
     */
    function getTimeToMaturity64x64(uint64 maturity)
        external
        view
        returns (int128);

    /**
     * @notice calculate the annualized volatility for given set of parameters
     * @param base The base token of the pair
     * @param underlying The underlying token of the pair
     * @param spot64x64 64x64 fixed point representation of spot price
     * @param strike64x64 64x64 fixed point representation of strike price
     * @param timeToMaturity64x64 64x64 fixed point representation of time to maturity (denominated in years)
     * @return 64x64 fixed point representation of annualized implied volatility, where 1 is defined as 100%
     */
    function getAnnualizedVolatility64x64(
        address base,
        address underlying,
        int128 spot64x64,
        int128 strike64x64,
        int128 timeToMaturity64x64
    ) external view returns (int128);

    /**
     * @notice calculate the price of an option using the Black-Scholes model
     * @param base The base token of the pair
     * @param underlying The underlying token of the pair
     * @param spot64x64 Spot price, as a 64x64 fixed point representation
     * @param strike64x64 Strike, as a64x64 fixed point representation
     * @param timeToMaturity64x64 64x64 fixed point representation of time to maturity (denominated in years)
     * @param isCall Whether it is for call or put
     * @return 64x64 fixed point representation of the Black Scholes price
     */
    function getBlackScholesPrice64x64(
        address base,
        address underlying,
        int128 spot64x64,
        int128 strike64x64,
        int128 timeToMaturity64x64,
        bool isCall
    ) external view returns (int128);

    /**
     * @notice Get Black Scholes price as an uint256 with 18 decimals
     * @param base The base token of the pair
     * @param underlying The underlying token of the pair
     * @param spot64x64 Spot price, as a 64x64 fixed point representation
     * @param strike64x64 Strike, as a64x64 fixed point representation
     * @param timeToMaturity64x64 64x64 fixed point representation of time to maturity (denominated in years)
     * @param isCall Whether it is for call or put
     * @return Black scholes price, as an uint256 with 18 decimals
     */
    function getBlackScholesPrice(
        address base,
        address underlying,
        int128 spot64x64,
        int128 strike64x64,
        int128 timeToMaturity64x64,
        bool isCall
    ) external view returns (uint256);

    /**
     * @notice Add relayers to the whitelist so that they can add oracle surfaces
     * @param accounts The addresses to add to the whitelist
     */
    function addWhitelistedRelayers(address[] memory accounts) external;

    /**
     * @notice Remove relayers from the whitelist so that they cannot add oracle surfaces
     * @param accounts The addresses to remove from the whitelist
     */
    function removeWhitelistedRelayers(address[] memory accounts) external;

    /**
     * @notice Update a list of IV model parameters
     * @param base List of base tokens
     * @param underlying List of underlying tokens
     * @param parameters List of IV model parameters
     */
    function updateParams(
        address[] memory base,
        address[] memory underlying,
        bytes32[] memory parameters
    ) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

library OwnableStorage {
    struct Layout {
        address owner;
    }

    bytes32 internal constant STORAGE_SLOT =
        keccak256('solidstate.contracts.storage.Ownable');

    function layout() internal pure returns (Layout storage l) {
        bytes32 slot = STORAGE_SLOT;
        assembly {
            l.slot := slot
        }
    }

    function setOwner(Layout storage l, address owner) internal {
        l.owner = owner;
    }
}