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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;

import {IERC20} from '@aave/core-v3/contracts/dependencies/openzeppelin/contracts/IERC20.sol';
import {GPv2SafeERC20} from '@aave/core-v3/contracts/dependencies/gnosis/contracts/GPv2SafeERC20.sol';
import {SafeCast} from '@openzeppelin/contracts/utils/math/SafeCast.sol';
import {IGhoFacilitator} from '../../gho/interfaces/IGhoFacilitator.sol';
import {IGhoToken} from '../../gho/interfaces/IGhoToken.sol';
import {IGsmPriceStrategy} from './priceStrategy/interfaces/IGsmPriceStrategy.sol';
import {IGsm4626} from './interfaces/IGsm4626.sol';
import {Gsm} from './Gsm.sol';

/**
 * @title Gsm4626
 * @author Aave
 * @notice GHO Stability Module for ERC4626 vault shares. It provides buy/sell facilities to go to/from an ERC4626
 * vault share to/from GHO.
 * @dev Aimed to be used with ERC4626 vault shares as underlying asset. Users can use the ERC4626 vault share to
 * buy/sell GHO and the generated yield is redirected to the GHO Treasury in form of GHO.
 * @dev To be covered by a proxy contract.
 */
contract Gsm4626 is Gsm, IGsm4626 {
  using GPv2SafeERC20 for IERC20;
  using SafeCast for uint256;

  /**
   * @dev Constructor
   * @param ghoToken The address of the GHO token contract
   * @param underlyingAsset The address of the ERC4626 vault
   * @param priceStrategy The address of the price strategy
   */
  constructor(
    address ghoToken,
    address underlyingAsset,
    address priceStrategy
  ) Gsm(ghoToken, underlyingAsset, priceStrategy) {
    // Intentionally left blank
  }

  /// @inheritdoc IGsm4626
  function backWithGho(
    uint256 amount
  ) external notSeized onlyRole(CONFIGURATOR_ROLE) returns (uint256) {
    require(amount > 0, 'INVALID_AMOUNT');

    (, uint256 ghoMinted) = IGhoToken(GHO_TOKEN).getFacilitatorBucket(address(this));
    (, uint256 deficit) = _getCurrentBacking(ghoMinted);
    require(deficit > 0, 'NO_CURRENT_DEFICIT_BACKING');

    uint256 ghoToBack = amount > deficit ? deficit : amount;

    IGhoToken(GHO_TOKEN).transferFrom(msg.sender, address(this), ghoToBack);
    IGhoToken(GHO_TOKEN).burn(ghoToBack);

    emit BackingProvided(msg.sender, GHO_TOKEN, ghoToBack, ghoToBack, deficit - ghoToBack);
    return ghoToBack;
  }

  /// @inheritdoc IGsm4626
  function backWithUnderlying(
    uint256 amount
  ) external notSeized onlyRole(CONFIGURATOR_ROLE) returns (uint256) {
    require(amount > 0, 'INVALID_AMOUNT');

    (, uint256 ghoMinted) = IGhoToken(GHO_TOKEN).getFacilitatorBucket(address(this));
    (, uint256 deficit) = _getCurrentBacking(ghoMinted);
    require(deficit > 0, 'NO_CURRENT_DEFICIT_BACKING');

    uint128 deficitInUnderlying = IGsmPriceStrategy(PRICE_STRATEGY)
      .getGhoPriceInAsset(deficit, false)
      .toUint128();

    if (amount >= deficitInUnderlying) {
      _currentExposure += deficitInUnderlying;
      IERC20(UNDERLYING_ASSET).safeTransferFrom(msg.sender, address(this), deficitInUnderlying);

      emit BackingProvided(msg.sender, UNDERLYING_ASSET, deficitInUnderlying, deficit, 0);
      return deficitInUnderlying;
    } else {
      uint256 amountInGho = IGsmPriceStrategy(PRICE_STRATEGY).getAssetPriceInGho(amount, false);

      _currentExposure += uint128(amount);
      IERC20(UNDERLYING_ASSET).safeTransferFrom(msg.sender, address(this), amount);

      emit BackingProvided(
        msg.sender,
        UNDERLYING_ASSET,
        amount,
        amountInGho,
        deficit - amountInGho
      );
      return amount;
    }
  }

  /// @inheritdoc IGsm4626
  function getCurrentBacking() external view returns (uint256, uint256) {
    (, uint256 ghoMinted) = IGhoToken(GHO_TOKEN).getFacilitatorBucket(address(this));
    return _getCurrentBacking(ghoMinted);
  }

  /// @inheritdoc IGhoFacilitator
  function distributeFeesToTreasury() public override(Gsm, IGhoFacilitator) {
    _cumulateYieldInGho();
    super.distributeFeesToTreasury();
  }

  /// @inheritdoc Gsm
  function _beforeBuyAsset(address, uint256, address) internal override {
    _cumulateYieldInGho();
  }

  /// @inheritdoc Gsm
  function _beforeSellAsset(address, uint256, address) internal override {}

  /**
   * @dev Cumulates yield in form of GHO, aimed to be redirected to the treasury
   * @dev It mints GHO backed by the excess of underlying produced by the ERC4626 yield
   * @dev If the GHO amount exceeds the amount available, it will mint up to the remaining capacity
   */
  function _cumulateYieldInGho() internal {
    (uint256 ghoCapacity, uint256 ghoLevel) = IGhoToken(GHO_TOKEN).getFacilitatorBucket(
      address(this)
    );
    uint256 ghoAvailableToMint = ghoCapacity > ghoLevel ? ghoCapacity - ghoLevel : 0;
    (uint256 ghoExcess, ) = _getCurrentBacking(ghoLevel);
    if (ghoExcess > 0 && ghoAvailableToMint > 0) {
      ghoExcess = ghoExcess > ghoAvailableToMint ? ghoAvailableToMint : ghoExcess;
      _accruedFees += uint128(ghoExcess);
      IGhoToken(GHO_TOKEN).mint(address(this), ghoExcess);
    }
  }

  /**
   * @dev Calculates the excess or deficit of GHO minted, reflective of GSM backing
   * @param ghoMinted The amount of GHO currently minted by the GSM
   * @return The excess amount of GHO minted, relative to the value of the underlying
   * @return The deficit of GHO minted, relative to the value of the underlying
   */
  function _getCurrentBacking(uint256 ghoMinted) internal view returns (uint256, uint256) {
    uint256 ghoToBack = IGsmPriceStrategy(PRICE_STRATEGY).getAssetPriceInGho(
      _currentExposure,
      false
    );
    if (ghoToBack >= ghoMinted) {
      return (ghoToBack - ghoMinted, 0);
    } else {
      return (0, ghoMinted - ghoToBack);
    }
  }
}

// SPDX-License-Identifier: AGPL-3.0
pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
  /**
   * @dev Returns the amount of tokens in existence.
   */
  function totalSupply() external view returns (uint256);

  /**
   * @dev Returns the amount of tokens owned by `account`.
   */
  function balanceOf(address account) external view returns (uint256);

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

  /**
   * @dev Returns the remaining number of tokens that `spender` will be
   * allowed to spend on behalf of `owner` through {transferFrom}. This is
   * zero by default.
   *
   * This value changes when {approve} or {transferFrom} are called.
   */
  function allowance(address owner, address spender) external view returns (uint256);

  /**
   * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
   *
   * Returns a boolean value indicating whether the operation succeeded.
   *
   * IMPORTANT: Beware that changing an allowance with this method brings the risk
   * that someone may use both the old and the new allowance by unfortunate
   * transaction ordering. One possible solution to mitigate this race
   * condition is to first reduce the spender's allowance to 0 and set the
   * desired value afterwards:
   * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
   *
   * Emits an {Approval} event.
   */
  function approve(address spender, uint256 amount) external returns (bool);

  /**
   * @dev Moves `amount` tokens from `sender` to `recipient` using the
   * allowance mechanism. `amount` is then deducted from the caller's
   * allowance.
   *
   * Returns a boolean value indicating whether the operation succeeded.
   *
   * Emits a {Transfer} event.
   */
  function transferFrom(
    address sender,
    address recipient,
    uint256 amount
  ) external returns (bool);

  /**
   * @dev Emitted when `value` tokens are moved from one account (`from`) to
   * another (`to`).
   *
   * Note that `value` may be zero.
   */
  event Transfer(address indexed from, address indexed to, uint256 value);

  /**
   * @dev Emitted when the allowance of a `spender` for an `owner` is set by
   * a call to {approve}. `value` is the new allowance.
   */
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

// SPDX-License-Identifier: LGPL-3.0-or-later
pragma solidity 0.8.10;

import {IERC20} from '../../openzeppelin/contracts/IERC20.sol';

/// @title Gnosis Protocol v2 Safe ERC20 Transfer Library
/// @author Gnosis Developers
/// @dev Gas-efficient version of Openzeppelin's SafeERC20 contract.
library GPv2SafeERC20 {
  /// @dev Wrapper around a call to the ERC20 function `transfer` that reverts
  /// also when the token returns `false`.
  function safeTransfer(
    IERC20 token,
    address to,
    uint256 value
  ) internal {
    bytes4 selector_ = token.transfer.selector;

    // solhint-disable-next-line no-inline-assembly
    assembly {
      let freeMemoryPointer := mload(0x40)
      mstore(freeMemoryPointer, selector_)
      mstore(add(freeMemoryPointer, 4), and(to, 0xffffffffffffffffffffffffffffffffffffffff))
      mstore(add(freeMemoryPointer, 36), value)

      if iszero(call(gas(), token, 0, freeMemoryPointer, 68, 0, 0)) {
        returndatacopy(0, 0, returndatasize())
        revert(0, returndatasize())
      }
    }

    require(getLastTransferResult(token), 'GPv2: failed transfer');
  }

  /// @dev Wrapper around a call to the ERC20 function `transferFrom` that
  /// reverts also when the token returns `false`.
  function safeTransferFrom(
    IERC20 token,
    address from,
    address to,
    uint256 value
  ) internal {
    bytes4 selector_ = token.transferFrom.selector;

    // solhint-disable-next-line no-inline-assembly
    assembly {
      let freeMemoryPointer := mload(0x40)
      mstore(freeMemoryPointer, selector_)
      mstore(add(freeMemoryPointer, 4), and(from, 0xffffffffffffffffffffffffffffffffffffffff))
      mstore(add(freeMemoryPointer, 36), and(to, 0xffffffffffffffffffffffffffffffffffffffff))
      mstore(add(freeMemoryPointer, 68), value)

      if iszero(call(gas(), token, 0, freeMemoryPointer, 100, 0, 0)) {
        returndatacopy(0, 0, returndatasize())
        revert(0, returndatasize())
      }
    }

    require(getLastTransferResult(token), 'GPv2: failed transferFrom');
  }

  /// @dev Verifies that the last return was a successful `transfer*` call.
  /// This is done by checking that the return data is either empty, or
  /// is a valid ABI encoded boolean.
  function getLastTransferResult(IERC20 token) private view returns (bool success) {
    // NOTE: Inspecting previous return data requires assembly. Note that
    // we write the return data to memory 0 in the case where the return
    // data size is 32, this is OK since the first 64 bytes of memory are
    // reserved by Solidy as a scratch space that can be used within
    // assembly blocks.
    // <https://docs.soliditylang.org/en/v0.7.6/internals/layout_in_memory.html>
    // solhint-disable-next-line no-inline-assembly
    assembly {
      /// @dev Revert with an ABI encoded Solidity error with a message
      /// that fits into 32-bytes.
      ///
      /// An ABI encoded Solidity error has the following memory layout:
      ///
      /// ------------+----------------------------------
      ///  byte range | value
      /// ------------+----------------------------------
      ///  0x00..0x04 |        selector("Error(string)")
      ///  0x04..0x24 |      string offset (always 0x20)
      ///  0x24..0x44 |                    string length
      ///  0x44..0x64 | string value, padded to 32-bytes
      function revertWithMessage(length, message) {
        mstore(0x00, '\x08\xc3\x79\xa0')
        mstore(0x04, 0x20)
        mstore(0x24, length)
        mstore(0x44, message)
        revert(0x00, 0x64)
      }

      switch returndatasize()
      // Non-standard ERC20 transfer without return.
      case 0 {
        // NOTE: When the return data size is 0, verify that there
        // is code at the address. This is done in order to maintain
        // compatibility with Solidity calling conventions.
        // <https://docs.soliditylang.org/en/v0.7.6/control-structures.html#external-function-calls>
        if iszero(extcodesize(token)) {
          revertWithMessage(20, 'GPv2: not a contract')
        }

        success := 1
      }
      // Standard ERC20 transfer returning boolean success value.
      case 32 {
        returndatacopy(0, 0, returndatasize())

        // NOTE: For ABI encoding v1, any non-zero value is accepted
        // as `true` for a boolean. In order to stay compatible with
        // OpenZeppelin's `SafeERC20` library which is known to work
        // with the existing ERC20 implementation we care about,
        // make sure we return success for any non-zero return value
        // from the `transfer*` call.
        success := iszero(iszero(mload(0)))
      }
      default {
        revertWithMessage(31, 'GPv2: malformed transfer result')
      }
    }
  }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/SafeCast.sol)
// This file was procedurally generated from scripts/generate/templates/SafeCast.js.

pragma solidity ^0.8.0;

/**
 * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
 * checks.
 *
 * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
 * easily result in undesired exploitation or bugs, since developers usually
 * assume that overflows raise errors. `SafeCast` restores this intuition by
 * reverting the transaction when such an operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 *
 * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing
 * all math on `uint256` and `int256` and then downcasting.
 */
library SafeCast {
    /**
     * @dev Returns the downcasted uint248 from uint256, reverting on
     * overflow (when the input is greater than largest uint248).
     *
     * Counterpart to Solidity's `uint248` operator.
     *
     * Requirements:
     *
     * - input must fit into 248 bits
     *
     * _Available since v4.7._
     */
    function toUint248(uint256 value) internal pure returns (uint248) {
        require(value <= type(uint248).max, "SafeCast: value doesn't fit in 248 bits");
        return uint248(value);
    }

    /**
     * @dev Returns the downcasted uint240 from uint256, reverting on
     * overflow (when the input is greater than largest uint240).
     *
     * Counterpart to Solidity's `uint240` operator.
     *
     * Requirements:
     *
     * - input must fit into 240 bits
     *
     * _Available since v4.7._
     */
    function toUint240(uint256 value) internal pure returns (uint240) {
        require(value <= type(uint240).max, "SafeCast: value doesn't fit in 240 bits");
        return uint240(value);
    }

    /**
     * @dev Returns the downcasted uint232 from uint256, reverting on
     * overflow (when the input is greater than largest uint232).
     *
     * Counterpart to Solidity's `uint232` operator.
     *
     * Requirements:
     *
     * - input must fit into 232 bits
     *
     * _Available since v4.7._
     */
    function toUint232(uint256 value) internal pure returns (uint232) {
        require(value <= type(uint232).max, "SafeCast: value doesn't fit in 232 bits");
        return uint232(value);
    }

    /**
     * @dev Returns the downcasted uint224 from uint256, reverting on
     * overflow (when the input is greater than largest uint224).
     *
     * Counterpart to Solidity's `uint224` operator.
     *
     * Requirements:
     *
     * - input must fit into 224 bits
     *
     * _Available since v4.2._
     */
    function toUint224(uint256 value) internal pure returns (uint224) {
        require(value <= type(uint224).max, "SafeCast: value doesn't fit in 224 bits");
        return uint224(value);
    }

    /**
     * @dev Returns the downcasted uint216 from uint256, reverting on
     * overflow (when the input is greater than largest uint216).
     *
     * Counterpart to Solidity's `uint216` operator.
     *
     * Requirements:
     *
     * - input must fit into 216 bits
     *
     * _Available since v4.7._
     */
    function toUint216(uint256 value) internal pure returns (uint216) {
        require(value <= type(uint216).max, "SafeCast: value doesn't fit in 216 bits");
        return uint216(value);
    }

    /**
     * @dev Returns the downcasted uint208 from uint256, reverting on
     * overflow (when the input is greater than largest uint208).
     *
     * Counterpart to Solidity's `uint208` operator.
     *
     * Requirements:
     *
     * - input must fit into 208 bits
     *
     * _Available since v4.7._
     */
    function toUint208(uint256 value) internal pure returns (uint208) {
        require(value <= type(uint208).max, "SafeCast: value doesn't fit in 208 bits");
        return uint208(value);
    }

    /**
     * @dev Returns the downcasted uint200 from uint256, reverting on
     * overflow (when the input is greater than largest uint200).
     *
     * Counterpart to Solidity's `uint200` operator.
     *
     * Requirements:
     *
     * - input must fit into 200 bits
     *
     * _Available since v4.7._
     */
    function toUint200(uint256 value) internal pure returns (uint200) {
        require(value <= type(uint200).max, "SafeCast: value doesn't fit in 200 bits");
        return uint200(value);
    }

    /**
     * @dev Returns the downcasted uint192 from uint256, reverting on
     * overflow (when the input is greater than largest uint192).
     *
     * Counterpart to Solidity's `uint192` operator.
     *
     * Requirements:
     *
     * - input must fit into 192 bits
     *
     * _Available since v4.7._
     */
    function toUint192(uint256 value) internal pure returns (uint192) {
        require(value <= type(uint192).max, "SafeCast: value doesn't fit in 192 bits");
        return uint192(value);
    }

    /**
     * @dev Returns the downcasted uint184 from uint256, reverting on
     * overflow (when the input is greater than largest uint184).
     *
     * Counterpart to Solidity's `uint184` operator.
     *
     * Requirements:
     *
     * - input must fit into 184 bits
     *
     * _Available since v4.7._
     */
    function toUint184(uint256 value) internal pure returns (uint184) {
        require(value <= type(uint184).max, "SafeCast: value doesn't fit in 184 bits");
        return uint184(value);
    }

    /**
     * @dev Returns the downcasted uint176 from uint256, reverting on
     * overflow (when the input is greater than largest uint176).
     *
     * Counterpart to Solidity's `uint176` operator.
     *
     * Requirements:
     *
     * - input must fit into 176 bits
     *
     * _Available since v4.7._
     */
    function toUint176(uint256 value) internal pure returns (uint176) {
        require(value <= type(uint176).max, "SafeCast: value doesn't fit in 176 bits");
        return uint176(value);
    }

    /**
     * @dev Returns the downcasted uint168 from uint256, reverting on
     * overflow (when the input is greater than largest uint168).
     *
     * Counterpart to Solidity's `uint168` operator.
     *
     * Requirements:
     *
     * - input must fit into 168 bits
     *
     * _Available since v4.7._
     */
    function toUint168(uint256 value) internal pure returns (uint168) {
        require(value <= type(uint168).max, "SafeCast: value doesn't fit in 168 bits");
        return uint168(value);
    }

    /**
     * @dev Returns the downcasted uint160 from uint256, reverting on
     * overflow (when the input is greater than largest uint160).
     *
     * Counterpart to Solidity's `uint160` operator.
     *
     * Requirements:
     *
     * - input must fit into 160 bits
     *
     * _Available since v4.7._
     */
    function toUint160(uint256 value) internal pure returns (uint160) {
        require(value <= type(uint160).max, "SafeCast: value doesn't fit in 160 bits");
        return uint160(value);
    }

    /**
     * @dev Returns the downcasted uint152 from uint256, reverting on
     * overflow (when the input is greater than largest uint152).
     *
     * Counterpart to Solidity's `uint152` operator.
     *
     * Requirements:
     *
     * - input must fit into 152 bits
     *
     * _Available since v4.7._
     */
    function toUint152(uint256 value) internal pure returns (uint152) {
        require(value <= type(uint152).max, "SafeCast: value doesn't fit in 152 bits");
        return uint152(value);
    }

    /**
     * @dev Returns the downcasted uint144 from uint256, reverting on
     * overflow (when the input is greater than largest uint144).
     *
     * Counterpart to Solidity's `uint144` operator.
     *
     * Requirements:
     *
     * - input must fit into 144 bits
     *
     * _Available since v4.7._
     */
    function toUint144(uint256 value) internal pure returns (uint144) {
        require(value <= type(uint144).max, "SafeCast: value doesn't fit in 144 bits");
        return uint144(value);
    }

    /**
     * @dev Returns the downcasted uint136 from uint256, reverting on
     * overflow (when the input is greater than largest uint136).
     *
     * Counterpart to Solidity's `uint136` operator.
     *
     * Requirements:
     *
     * - input must fit into 136 bits
     *
     * _Available since v4.7._
     */
    function toUint136(uint256 value) internal pure returns (uint136) {
        require(value <= type(uint136).max, "SafeCast: value doesn't fit in 136 bits");
        return uint136(value);
    }

    /**
     * @dev Returns the downcasted uint128 from uint256, reverting on
     * overflow (when the input is greater than largest uint128).
     *
     * Counterpart to Solidity's `uint128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v2.5._
     */
    function toUint128(uint256 value) internal pure returns (uint128) {
        require(value <= type(uint128).max, "SafeCast: value doesn't fit in 128 bits");
        return uint128(value);
    }

    /**
     * @dev Returns the downcasted uint120 from uint256, reverting on
     * overflow (when the input is greater than largest uint120).
     *
     * Counterpart to Solidity's `uint120` operator.
     *
     * Requirements:
     *
     * - input must fit into 120 bits
     *
     * _Available since v4.7._
     */
    function toUint120(uint256 value) internal pure returns (uint120) {
        require(value <= type(uint120).max, "SafeCast: value doesn't fit in 120 bits");
        return uint120(value);
    }

    /**
     * @dev Returns the downcasted uint112 from uint256, reverting on
     * overflow (when the input is greater than largest uint112).
     *
     * Counterpart to Solidity's `uint112` operator.
     *
     * Requirements:
     *
     * - input must fit into 112 bits
     *
     * _Available since v4.7._
     */
    function toUint112(uint256 value) internal pure returns (uint112) {
        require(value <= type(uint112).max, "SafeCast: value doesn't fit in 112 bits");
        return uint112(value);
    }

    /**
     * @dev Returns the downcasted uint104 from uint256, reverting on
     * overflow (when the input is greater than largest uint104).
     *
     * Counterpart to Solidity's `uint104` operator.
     *
     * Requirements:
     *
     * - input must fit into 104 bits
     *
     * _Available since v4.7._
     */
    function toUint104(uint256 value) internal pure returns (uint104) {
        require(value <= type(uint104).max, "SafeCast: value doesn't fit in 104 bits");
        return uint104(value);
    }

    /**
     * @dev Returns the downcasted uint96 from uint256, reverting on
     * overflow (when the input is greater than largest uint96).
     *
     * Counterpart to Solidity's `uint96` operator.
     *
     * Requirements:
     *
     * - input must fit into 96 bits
     *
     * _Available since v4.2._
     */
    function toUint96(uint256 value) internal pure returns (uint96) {
        require(value <= type(uint96).max, "SafeCast: value doesn't fit in 96 bits");
        return uint96(value);
    }

    /**
     * @dev Returns the downcasted uint88 from uint256, reverting on
     * overflow (when the input is greater than largest uint88).
     *
     * Counterpart to Solidity's `uint88` operator.
     *
     * Requirements:
     *
     * - input must fit into 88 bits
     *
     * _Available since v4.7._
     */
    function toUint88(uint256 value) internal pure returns (uint88) {
        require(value <= type(uint88).max, "SafeCast: value doesn't fit in 88 bits");
        return uint88(value);
    }

    /**
     * @dev Returns the downcasted uint80 from uint256, reverting on
     * overflow (when the input is greater than largest uint80).
     *
     * Counterpart to Solidity's `uint80` operator.
     *
     * Requirements:
     *
     * - input must fit into 80 bits
     *
     * _Available since v4.7._
     */
    function toUint80(uint256 value) internal pure returns (uint80) {
        require(value <= type(uint80).max, "SafeCast: value doesn't fit in 80 bits");
        return uint80(value);
    }

    /**
     * @dev Returns the downcasted uint72 from uint256, reverting on
     * overflow (when the input is greater than largest uint72).
     *
     * Counterpart to Solidity's `uint72` operator.
     *
     * Requirements:
     *
     * - input must fit into 72 bits
     *
     * _Available since v4.7._
     */
    function toUint72(uint256 value) internal pure returns (uint72) {
        require(value <= type(uint72).max, "SafeCast: value doesn't fit in 72 bits");
        return uint72(value);
    }

    /**
     * @dev Returns the downcasted uint64 from uint256, reverting on
     * overflow (when the input is greater than largest uint64).
     *
     * Counterpart to Solidity's `uint64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v2.5._
     */
    function toUint64(uint256 value) internal pure returns (uint64) {
        require(value <= type(uint64).max, "SafeCast: value doesn't fit in 64 bits");
        return uint64(value);
    }

    /**
     * @dev Returns the downcasted uint56 from uint256, reverting on
     * overflow (when the input is greater than largest uint56).
     *
     * Counterpart to Solidity's `uint56` operator.
     *
     * Requirements:
     *
     * - input must fit into 56 bits
     *
     * _Available since v4.7._
     */
    function toUint56(uint256 value) internal pure returns (uint56) {
        require(value <= type(uint56).max, "SafeCast: value doesn't fit in 56 bits");
        return uint56(value);
    }

    /**
     * @dev Returns the downcasted uint48 from uint256, reverting on
     * overflow (when the input is greater than largest uint48).
     *
     * Counterpart to Solidity's `uint48` operator.
     *
     * Requirements:
     *
     * - input must fit into 48 bits
     *
     * _Available since v4.7._
     */
    function toUint48(uint256 value) internal pure returns (uint48) {
        require(value <= type(uint48).max, "SafeCast: value doesn't fit in 48 bits");
        return uint48(value);
    }

    /**
     * @dev Returns the downcasted uint40 from uint256, reverting on
     * overflow (when the input is greater than largest uint40).
     *
     * Counterpart to Solidity's `uint40` operator.
     *
     * Requirements:
     *
     * - input must fit into 40 bits
     *
     * _Available since v4.7._
     */
    function toUint40(uint256 value) internal pure returns (uint40) {
        require(value <= type(uint40).max, "SafeCast: value doesn't fit in 40 bits");
        return uint40(value);
    }

    /**
     * @dev Returns the downcasted uint32 from uint256, reverting on
     * overflow (when the input is greater than largest uint32).
     *
     * Counterpart to Solidity's `uint32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v2.5._
     */
    function toUint32(uint256 value) internal pure returns (uint32) {
        require(value <= type(uint32).max, "SafeCast: value doesn't fit in 32 bits");
        return uint32(value);
    }

    /**
     * @dev Returns the downcasted uint24 from uint256, reverting on
     * overflow (when the input is greater than largest uint24).
     *
     * Counterpart to Solidity's `uint24` operator.
     *
     * Requirements:
     *
     * - input must fit into 24 bits
     *
     * _Available since v4.7._
     */
    function toUint24(uint256 value) internal pure returns (uint24) {
        require(value <= type(uint24).max, "SafeCast: value doesn't fit in 24 bits");
        return uint24(value);
    }

    /**
     * @dev Returns the downcasted uint16 from uint256, reverting on
     * overflow (when the input is greater than largest uint16).
     *
     * Counterpart to Solidity's `uint16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v2.5._
     */
    function toUint16(uint256 value) internal pure returns (uint16) {
        require(value <= type(uint16).max, "SafeCast: value doesn't fit in 16 bits");
        return uint16(value);
    }

    /**
     * @dev Returns the downcasted uint8 from uint256, reverting on
     * overflow (when the input is greater than largest uint8).
     *
     * Counterpart to Solidity's `uint8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits
     *
     * _Available since v2.5._
     */
    function toUint8(uint256 value) internal pure returns (uint8) {
        require(value <= type(uint8).max, "SafeCast: value doesn't fit in 8 bits");
        return uint8(value);
    }

    /**
     * @dev Converts a signed int256 into an unsigned uint256.
     *
     * Requirements:
     *
     * - input must be greater than or equal to 0.
     *
     * _Available since v3.0._
     */
    function toUint256(int256 value) internal pure returns (uint256) {
        require(value >= 0, "SafeCast: value must be positive");
        return uint256(value);
    }

    /**
     * @dev Returns the downcasted int248 from int256, reverting on
     * overflow (when the input is less than smallest int248 or
     * greater than largest int248).
     *
     * Counterpart to Solidity's `int248` operator.
     *
     * Requirements:
     *
     * - input must fit into 248 bits
     *
     * _Available since v4.7._
     */
    function toInt248(int256 value) internal pure returns (int248 downcasted) {
        downcasted = int248(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 248 bits");
    }

    /**
     * @dev Returns the downcasted int240 from int256, reverting on
     * overflow (when the input is less than smallest int240 or
     * greater than largest int240).
     *
     * Counterpart to Solidity's `int240` operator.
     *
     * Requirements:
     *
     * - input must fit into 240 bits
     *
     * _Available since v4.7._
     */
    function toInt240(int256 value) internal pure returns (int240 downcasted) {
        downcasted = int240(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 240 bits");
    }

    /**
     * @dev Returns the downcasted int232 from int256, reverting on
     * overflow (when the input is less than smallest int232 or
     * greater than largest int232).
     *
     * Counterpart to Solidity's `int232` operator.
     *
     * Requirements:
     *
     * - input must fit into 232 bits
     *
     * _Available since v4.7._
     */
    function toInt232(int256 value) internal pure returns (int232 downcasted) {
        downcasted = int232(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 232 bits");
    }

    /**
     * @dev Returns the downcasted int224 from int256, reverting on
     * overflow (when the input is less than smallest int224 or
     * greater than largest int224).
     *
     * Counterpart to Solidity's `int224` operator.
     *
     * Requirements:
     *
     * - input must fit into 224 bits
     *
     * _Available since v4.7._
     */
    function toInt224(int256 value) internal pure returns (int224 downcasted) {
        downcasted = int224(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 224 bits");
    }

    /**
     * @dev Returns the downcasted int216 from int256, reverting on
     * overflow (when the input is less than smallest int216 or
     * greater than largest int216).
     *
     * Counterpart to Solidity's `int216` operator.
     *
     * Requirements:
     *
     * - input must fit into 216 bits
     *
     * _Available since v4.7._
     */
    function toInt216(int256 value) internal pure returns (int216 downcasted) {
        downcasted = int216(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 216 bits");
    }

    /**
     * @dev Returns the downcasted int208 from int256, reverting on
     * overflow (when the input is less than smallest int208 or
     * greater than largest int208).
     *
     * Counterpart to Solidity's `int208` operator.
     *
     * Requirements:
     *
     * - input must fit into 208 bits
     *
     * _Available since v4.7._
     */
    function toInt208(int256 value) internal pure returns (int208 downcasted) {
        downcasted = int208(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 208 bits");
    }

    /**
     * @dev Returns the downcasted int200 from int256, reverting on
     * overflow (when the input is less than smallest int200 or
     * greater than largest int200).
     *
     * Counterpart to Solidity's `int200` operator.
     *
     * Requirements:
     *
     * - input must fit into 200 bits
     *
     * _Available since v4.7._
     */
    function toInt200(int256 value) internal pure returns (int200 downcasted) {
        downcasted = int200(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 200 bits");
    }

    /**
     * @dev Returns the downcasted int192 from int256, reverting on
     * overflow (when the input is less than smallest int192 or
     * greater than largest int192).
     *
     * Counterpart to Solidity's `int192` operator.
     *
     * Requirements:
     *
     * - input must fit into 192 bits
     *
     * _Available since v4.7._
     */
    function toInt192(int256 value) internal pure returns (int192 downcasted) {
        downcasted = int192(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 192 bits");
    }

    /**
     * @dev Returns the downcasted int184 from int256, reverting on
     * overflow (when the input is less than smallest int184 or
     * greater than largest int184).
     *
     * Counterpart to Solidity's `int184` operator.
     *
     * Requirements:
     *
     * - input must fit into 184 bits
     *
     * _Available since v4.7._
     */
    function toInt184(int256 value) internal pure returns (int184 downcasted) {
        downcasted = int184(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 184 bits");
    }

    /**
     * @dev Returns the downcasted int176 from int256, reverting on
     * overflow (when the input is less than smallest int176 or
     * greater than largest int176).
     *
     * Counterpart to Solidity's `int176` operator.
     *
     * Requirements:
     *
     * - input must fit into 176 bits
     *
     * _Available since v4.7._
     */
    function toInt176(int256 value) internal pure returns (int176 downcasted) {
        downcasted = int176(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 176 bits");
    }

    /**
     * @dev Returns the downcasted int168 from int256, reverting on
     * overflow (when the input is less than smallest int168 or
     * greater than largest int168).
     *
     * Counterpart to Solidity's `int168` operator.
     *
     * Requirements:
     *
     * - input must fit into 168 bits
     *
     * _Available since v4.7._
     */
    function toInt168(int256 value) internal pure returns (int168 downcasted) {
        downcasted = int168(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 168 bits");
    }

    /**
     * @dev Returns the downcasted int160 from int256, reverting on
     * overflow (when the input is less than smallest int160 or
     * greater than largest int160).
     *
     * Counterpart to Solidity's `int160` operator.
     *
     * Requirements:
     *
     * - input must fit into 160 bits
     *
     * _Available since v4.7._
     */
    function toInt160(int256 value) internal pure returns (int160 downcasted) {
        downcasted = int160(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 160 bits");
    }

    /**
     * @dev Returns the downcasted int152 from int256, reverting on
     * overflow (when the input is less than smallest int152 or
     * greater than largest int152).
     *
     * Counterpart to Solidity's `int152` operator.
     *
     * Requirements:
     *
     * - input must fit into 152 bits
     *
     * _Available since v4.7._
     */
    function toInt152(int256 value) internal pure returns (int152 downcasted) {
        downcasted = int152(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 152 bits");
    }

    /**
     * @dev Returns the downcasted int144 from int256, reverting on
     * overflow (when the input is less than smallest int144 or
     * greater than largest int144).
     *
     * Counterpart to Solidity's `int144` operator.
     *
     * Requirements:
     *
     * - input must fit into 144 bits
     *
     * _Available since v4.7._
     */
    function toInt144(int256 value) internal pure returns (int144 downcasted) {
        downcasted = int144(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 144 bits");
    }

    /**
     * @dev Returns the downcasted int136 from int256, reverting on
     * overflow (when the input is less than smallest int136 or
     * greater than largest int136).
     *
     * Counterpart to Solidity's `int136` operator.
     *
     * Requirements:
     *
     * - input must fit into 136 bits
     *
     * _Available since v4.7._
     */
    function toInt136(int256 value) internal pure returns (int136 downcasted) {
        downcasted = int136(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 136 bits");
    }

    /**
     * @dev Returns the downcasted int128 from int256, reverting on
     * overflow (when the input is less than smallest int128 or
     * greater than largest int128).
     *
     * Counterpart to Solidity's `int128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v3.1._
     */
    function toInt128(int256 value) internal pure returns (int128 downcasted) {
        downcasted = int128(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 128 bits");
    }

    /**
     * @dev Returns the downcasted int120 from int256, reverting on
     * overflow (when the input is less than smallest int120 or
     * greater than largest int120).
     *
     * Counterpart to Solidity's `int120` operator.
     *
     * Requirements:
     *
     * - input must fit into 120 bits
     *
     * _Available since v4.7._
     */
    function toInt120(int256 value) internal pure returns (int120 downcasted) {
        downcasted = int120(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 120 bits");
    }

    /**
     * @dev Returns the downcasted int112 from int256, reverting on
     * overflow (when the input is less than smallest int112 or
     * greater than largest int112).
     *
     * Counterpart to Solidity's `int112` operator.
     *
     * Requirements:
     *
     * - input must fit into 112 bits
     *
     * _Available since v4.7._
     */
    function toInt112(int256 value) internal pure returns (int112 downcasted) {
        downcasted = int112(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 112 bits");
    }

    /**
     * @dev Returns the downcasted int104 from int256, reverting on
     * overflow (when the input is less than smallest int104 or
     * greater than largest int104).
     *
     * Counterpart to Solidity's `int104` operator.
     *
     * Requirements:
     *
     * - input must fit into 104 bits
     *
     * _Available since v4.7._
     */
    function toInt104(int256 value) internal pure returns (int104 downcasted) {
        downcasted = int104(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 104 bits");
    }

    /**
     * @dev Returns the downcasted int96 from int256, reverting on
     * overflow (when the input is less than smallest int96 or
     * greater than largest int96).
     *
     * Counterpart to Solidity's `int96` operator.
     *
     * Requirements:
     *
     * - input must fit into 96 bits
     *
     * _Available since v4.7._
     */
    function toInt96(int256 value) internal pure returns (int96 downcasted) {
        downcasted = int96(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 96 bits");
    }

    /**
     * @dev Returns the downcasted int88 from int256, reverting on
     * overflow (when the input is less than smallest int88 or
     * greater than largest int88).
     *
     * Counterpart to Solidity's `int88` operator.
     *
     * Requirements:
     *
     * - input must fit into 88 bits
     *
     * _Available since v4.7._
     */
    function toInt88(int256 value) internal pure returns (int88 downcasted) {
        downcasted = int88(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 88 bits");
    }

    /**
     * @dev Returns the downcasted int80 from int256, reverting on
     * overflow (when the input is less than smallest int80 or
     * greater than largest int80).
     *
     * Counterpart to Solidity's `int80` operator.
     *
     * Requirements:
     *
     * - input must fit into 80 bits
     *
     * _Available since v4.7._
     */
    function toInt80(int256 value) internal pure returns (int80 downcasted) {
        downcasted = int80(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 80 bits");
    }

    /**
     * @dev Returns the downcasted int72 from int256, reverting on
     * overflow (when the input is less than smallest int72 or
     * greater than largest int72).
     *
     * Counterpart to Solidity's `int72` operator.
     *
     * Requirements:
     *
     * - input must fit into 72 bits
     *
     * _Available since v4.7._
     */
    function toInt72(int256 value) internal pure returns (int72 downcasted) {
        downcasted = int72(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 72 bits");
    }

    /**
     * @dev Returns the downcasted int64 from int256, reverting on
     * overflow (when the input is less than smallest int64 or
     * greater than largest int64).
     *
     * Counterpart to Solidity's `int64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v3.1._
     */
    function toInt64(int256 value) internal pure returns (int64 downcasted) {
        downcasted = int64(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 64 bits");
    }

    /**
     * @dev Returns the downcasted int56 from int256, reverting on
     * overflow (when the input is less than smallest int56 or
     * greater than largest int56).
     *
     * Counterpart to Solidity's `int56` operator.
     *
     * Requirements:
     *
     * - input must fit into 56 bits
     *
     * _Available since v4.7._
     */
    function toInt56(int256 value) internal pure returns (int56 downcasted) {
        downcasted = int56(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 56 bits");
    }

    /**
     * @dev Returns the downcasted int48 from int256, reverting on
     * overflow (when the input is less than smallest int48 or
     * greater than largest int48).
     *
     * Counterpart to Solidity's `int48` operator.
     *
     * Requirements:
     *
     * - input must fit into 48 bits
     *
     * _Available since v4.7._
     */
    function toInt48(int256 value) internal pure returns (int48 downcasted) {
        downcasted = int48(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 48 bits");
    }

    /**
     * @dev Returns the downcasted int40 from int256, reverting on
     * overflow (when the input is less than smallest int40 or
     * greater than largest int40).
     *
     * Counterpart to Solidity's `int40` operator.
     *
     * Requirements:
     *
     * - input must fit into 40 bits
     *
     * _Available since v4.7._
     */
    function toInt40(int256 value) internal pure returns (int40 downcasted) {
        downcasted = int40(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 40 bits");
    }

    /**
     * @dev Returns the downcasted int32 from int256, reverting on
     * overflow (when the input is less than smallest int32 or
     * greater than largest int32).
     *
     * Counterpart to Solidity's `int32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v3.1._
     */
    function toInt32(int256 value) internal pure returns (int32 downcasted) {
        downcasted = int32(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 32 bits");
    }

    /**
     * @dev Returns the downcasted int24 from int256, reverting on
     * overflow (when the input is less than smallest int24 or
     * greater than largest int24).
     *
     * Counterpart to Solidity's `int24` operator.
     *
     * Requirements:
     *
     * - input must fit into 24 bits
     *
     * _Available since v4.7._
     */
    function toInt24(int256 value) internal pure returns (int24 downcasted) {
        downcasted = int24(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 24 bits");
    }

    /**
     * @dev Returns the downcasted int16 from int256, reverting on
     * overflow (when the input is less than smallest int16 or
     * greater than largest int16).
     *
     * Counterpart to Solidity's `int16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v3.1._
     */
    function toInt16(int256 value) internal pure returns (int16 downcasted) {
        downcasted = int16(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 16 bits");
    }

    /**
     * @dev Returns the downcasted int8 from int256, reverting on
     * overflow (when the input is less than smallest int8 or
     * greater than largest int8).
     *
     * Counterpart to Solidity's `int8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits
     *
     * _Available since v3.1._
     */
    function toInt8(int256 value) internal pure returns (int8 downcasted) {
        downcasted = int8(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 8 bits");
    }

    /**
     * @dev Converts an unsigned uint256 into a signed int256.
     *
     * Requirements:
     *
     * - input must be less than or equal to maxInt256.
     *
     * _Available since v3.0._
     */
    function toInt256(uint256 value) internal pure returns (int256) {
        // Note: Unsafe cast below is okay because `type(int256).max` is guaranteed to be positive
        require(value <= uint256(type(int256).max), "SafeCast: value doesn't fit in an int256");
        return int256(value);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/**
 * @title IGhoFacilitator
 * @author Aave
 * @notice Defines the behavior of a Gho Facilitator
 */
interface IGhoFacilitator {
  /**
   * @dev Emitted when fees are distributed to the GhoTreasury
   * @param ghoTreasury The address of the ghoTreasury
   * @param asset The address of the asset transferred to the ghoTreasury
   * @param amount The amount of the asset transferred to the ghoTreasury
   */
  event FeesDistributedToTreasury(
    address indexed ghoTreasury,
    address indexed asset,
    uint256 amount
  );

  /**
   * @dev Emitted when Gho Treasury address is updated
   * @param oldGhoTreasury The address of the old GhoTreasury contract
   * @param newGhoTreasury The address of the new GhoTreasury contract
   */
  event GhoTreasuryUpdated(address indexed oldGhoTreasury, address indexed newGhoTreasury);

  /**
   * @notice Distribute fees to the GhoTreasury
   */
  function distributeFeesToTreasury() external;

  /**
   * @notice Updates the address of the Gho Treasury
   * @dev WARNING: The GhoTreasury is where revenue fees are sent to. Update carefully
   * @param newGhoTreasury The address of the GhoTreasury
   */
  function updateGhoTreasury(address newGhoTreasury) external;

  /**
   * @notice Returns the address of the Gho Treasury
   * @return The address of the GhoTreasury contract
   */
  function getGhoTreasury() external view returns (address);
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {IERC20} from '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import {IAccessControl} from '@openzeppelin/contracts/access/IAccessControl.sol';

/**
 * @title IGhoToken
 * @author Aave
 */
interface IGhoToken is IERC20, IAccessControl {
  struct Facilitator {
    uint128 bucketCapacity;
    uint128 bucketLevel;
    string label;
  }

  /**
   * @dev Emitted when a new facilitator is added
   * @param facilitatorAddress The address of the new facilitator
   * @param label A hashed human readable identifier for the facilitator
   * @param bucketCapacity The initial capacity of the facilitator's bucket
   */
  event FacilitatorAdded(
    address indexed facilitatorAddress,
    bytes32 indexed label,
    uint256 bucketCapacity
  );

  /**
   * @dev Emitted when a facilitator is removed
   * @param facilitatorAddress The address of the removed facilitator
   */
  event FacilitatorRemoved(address indexed facilitatorAddress);

  /**
   * @dev Emitted when the bucket capacity of a facilitator is updated
   * @param facilitatorAddress The address of the facilitator whose bucket capacity is being changed
   * @param oldCapacity The old capacity of the bucket
   * @param newCapacity The new capacity of the bucket
   */
  event FacilitatorBucketCapacityUpdated(
    address indexed facilitatorAddress,
    uint256 oldCapacity,
    uint256 newCapacity
  );

  /**
   * @dev Emitted when the bucket level changed
   * @param facilitatorAddress The address of the facilitator whose bucket level is being changed
   * @param oldLevel The old level of the bucket
   * @param newLevel The new level of the bucket
   */
  event FacilitatorBucketLevelUpdated(
    address indexed facilitatorAddress,
    uint256 oldLevel,
    uint256 newLevel
  );

  /**
   * @notice Returns the identifier of the Facilitator Manager Role
   * @return The bytes32 id hash of the FacilitatorManager role
   */
  function FACILITATOR_MANAGER_ROLE() external pure returns (bytes32);

  /**
   * @notice Returns the identifier of the Bucket Manager Role
   * @return The bytes32 id hash of the BucketManager role
   */
  function BUCKET_MANAGER_ROLE() external pure returns (bytes32);

  /**
   * @notice Mints the requested amount of tokens to the account address.
   * @dev Only facilitators with enough bucket capacity available can mint.
   * @dev The bucket level is increased upon minting.
   * @param account The address receiving the GHO tokens
   * @param amount The amount to mint
   */
  function mint(address account, uint256 amount) external;

  /**
   * @notice Burns the requested amount of tokens from the account address.
   * @dev Only active facilitators (bucket level > 0) can burn.
   * @dev The bucket level is decreased upon burning.
   * @param amount The amount to burn
   */
  function burn(uint256 amount) external;

  /**
   * @notice Add the facilitator passed with the parameters to the facilitators list.
   * @dev Only accounts with `FACILITATOR_MANAGER_ROLE` role can call this function
   * @param facilitatorAddress The address of the facilitator to add
   * @param facilitatorLabel A human readable identifier for the facilitator
   * @param bucketCapacity The upward limit of GHO can be minted by the facilitator
   */
  function addFacilitator(
    address facilitatorAddress,
    string calldata facilitatorLabel,
    uint128 bucketCapacity
  ) external;

  /**
   * @notice Remove the facilitator from the facilitators list.
   * @dev Only accounts with `FACILITATOR_MANAGER_ROLE` role can call this function
   * @param facilitatorAddress The address of the facilitator to remove
   */
  function removeFacilitator(address facilitatorAddress) external;

  /**
   * @notice Set the bucket capacity of the facilitator.
   * @dev Only accounts with `BUCKET_MANAGER_ROLE` role can call this function
   * @param facilitator The address of the facilitator
   * @param newCapacity The new capacity of the bucket
   */
  function setFacilitatorBucketCapacity(address facilitator, uint128 newCapacity) external;

  /**
   * @notice Returns the facilitator data
   * @param facilitator The address of the facilitator
   * @return The facilitator configuration
   */
  function getFacilitator(address facilitator) external view returns (Facilitator memory);

  /**
   * @notice Returns the bucket configuration of the facilitator
   * @param facilitator The address of the facilitator
   * @return The capacity of the facilitator's bucket
   * @return The level of the facilitator's bucket
   */
  function getFacilitatorBucket(address facilitator) external view returns (uint256, uint256);

  /**
   * @notice Returns the list of the addresses of the active facilitator
   * @return The list of the facilitators addresses
   */
  function getFacilitatorsList() external view returns (address[] memory);
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/**
 * @title IGsmPriceStrategy
 * @author Aave
 * @notice Defines the behaviour of Price Strategies
 */
interface IGsmPriceStrategy {
  /**
   * @notice Returns the number of decimals of GHO
   * @return The number of decimals of GHO
   */
  function GHO_DECIMALS() external view returns (uint256);

  /**
   * @notice Returns the address of the underlying asset being priced
   * @return The address of the underlying asset
   */
  function UNDERLYING_ASSET() external view returns (address);

  /**
   * @notice Returns the decimals of the underlying asset being priced
   * @return The number of decimals of the underlying asset
   */
  function UNDERLYING_ASSET_DECIMALS() external view returns (uint256);

  /**
   * @notice Returns the price of the underlying asset (GHO denominated)
   * @param assetAmount The amount of the underlying asset to calculate the price of
   * @param roundUp True if the price should be rounded up, false if rounded down
   * @return The price of the underlying asset (expressed in GHO units)
   */
  function getAssetPriceInGho(uint256 assetAmount, bool roundUp) external view returns (uint256);

  /**
   * @notice Returns the price of GHO (denominated in the underlying asset)
   * @param ghoAmount The amount of GHO to calculate the price of
   * @param roundUp True if the price should be rounded up, false if rounded down
   * @return The price of the GHO amount (expressed in underlying asset units)
   */
  function getGhoPriceInAsset(uint256 ghoAmount, bool roundUp) external view returns (uint256);
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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

/**
 * @title IGsm4626
 * @author Aave
 * @notice Defines the behaviour of a GHO Stability Module with an ERC-4626 underlying asset
 */
interface IGsm4626 is IGsm {
  /**
   * @dev Emitted when an asset is provided to the GSM to backstop a loss
   * @param backer The address of the backer
   * @param asset The address of the provided asset
   * @param amount The amount of the asset
   * @param ghoAmount The amount of the asset, in GHO terms
   * @param remainingLoss The loss balance that remains after the operation
   */
  event BackingProvided(
    address indexed backer,
    address indexed asset,
    uint256 amount,
    uint256 ghoAmount,
    uint256 remainingLoss
  );

  /**
   * @notice Restores backing of GHO by burning GHO
   * @dev Useful in the event the underlying value declines relative to GHO minted
   * @dev Passing an amount higher than the current deficit will result in backing the entire deficit
   * @param amount The amount of GHO to be burned
   * @return The amount of GHO used for backing
   */
  function backWithGho(uint256 amount) external returns (uint256);

  /**
   * @notice Restores backing of GHO by providing underlying asset
   * @dev Useful in the event the underlying value declines relative to GHO minted
   * @dev Passing an amount higher than the current deficit will result in backing the entire deficit
   * @param amount The amount of underlying to be used for backing
   * @return The amount of underlying used for backing
   */
  function backWithUnderlying(uint256 amount) external returns (uint256);

  /**
   * @notice Returns the excess or deficit of GHO, reflecting current GSM backing
   * @return The excess amount of GHO minted, relative to the value of the underlying
   * @return The deficit of GHO minted, relative to the value of the underlying
   */
  function getCurrentBacking() external view returns (uint256, uint256);
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;

import {VersionedInitializable} from '@aave/core-v3/contracts/protocol/libraries/aave-upgradeability/VersionedInitializable.sol';
import {IERC20} from '@aave/core-v3/contracts/dependencies/openzeppelin/contracts/IERC20.sol';
import {GPv2SafeERC20} from '@aave/core-v3/contracts/dependencies/gnosis/contracts/GPv2SafeERC20.sol';
import {EIP712} from '@openzeppelin/contracts/utils/cryptography/EIP712.sol';
import {SignatureChecker} from '@openzeppelin/contracts/utils/cryptography/SignatureChecker.sol';
import {SafeCast} from '@openzeppelin/contracts/utils/math/SafeCast.sol';
import {AccessControl} from '@openzeppelin/contracts/access/AccessControl.sol';
import {IGhoFacilitator} from '../../gho/interfaces/IGhoFacilitator.sol';
import {IGhoToken} from '../../gho/interfaces/IGhoToken.sol';
import {IGsmPriceStrategy} from './priceStrategy/interfaces/IGsmPriceStrategy.sol';
import {IGsmFeeStrategy} from './feeStrategy/interfaces/IGsmFeeStrategy.sol';
import {IGsm} from './interfaces/IGsm.sol';

/**
 * @title Gsm
 * @author Aave
 * @notice GHO Stability Module. It provides buy/sell facilities to go to/from an underlying asset to/from GHO.
 * @dev To be covered by a proxy contract.
 */
contract Gsm is AccessControl, VersionedInitializable, EIP712, IGsm {
  using GPv2SafeERC20 for IERC20;
  using SafeCast for uint256;

  /// @inheritdoc IGsm
  bytes32 public constant CONFIGURATOR_ROLE = keccak256('CONFIGURATOR_ROLE');

  /// @inheritdoc IGsm
  bytes32 public constant TOKEN_RESCUER_ROLE = keccak256('TOKEN_RESCUER_ROLE');

  /// @inheritdoc IGsm
  bytes32 public constant SWAP_FREEZER_ROLE = keccak256('SWAP_FREEZER_ROLE');

  /// @inheritdoc IGsm
  bytes32 public constant LIQUIDATOR_ROLE = keccak256('LIQUIDATOR_ROLE');

  /// @inheritdoc IGsm
  bytes32 public constant BUY_ASSET_WITH_SIG_TYPEHASH =
    keccak256(
      'BuyAssetWithSig(address originator,uint256 minAmount,address receiver,uint256 nonce,uint256 deadline)'
    );

  /// @inheritdoc IGsm
  bytes32 public constant SELL_ASSET_WITH_SIG_TYPEHASH =
    keccak256(
      'SellAssetWithSig(address originator,uint256 maxAmount,address receiver,uint256 nonce,uint256 deadline)'
    );

  /// @inheritdoc IGsm
  address public immutable GHO_TOKEN;

  /// @inheritdoc IGsm
  address public immutable UNDERLYING_ASSET;

  /// @inheritdoc IGsm
  address public immutable PRICE_STRATEGY;

  /// @inheritdoc IGsm
  mapping(address => uint256) public nonces;

  address internal _ghoTreasury;
  address internal _feeStrategy;
  bool internal _isFrozen;
  bool internal _isSeized;
  uint128 internal _exposureCap;
  uint128 internal _currentExposure;
  uint128 internal _accruedFees;

  /**
   * @dev Require GSM to not be frozen for functions marked by this modifier
   */
  modifier notFrozen() {
    require(!_isFrozen, 'GSM_FROZEN');
    _;
  }

  /**
   * @dev Require GSM to not be seized for functions marked by this modifier
   */
  modifier notSeized() {
    require(!_isSeized, 'GSM_SEIZED');
    _;
  }

  /**
   * @dev Constructor
   * @param ghoToken The address of the GHO token contract
   * @param underlyingAsset The address of the collateral asset
   * @param priceStrategy The address of the price strategy
   */
  constructor(address ghoToken, address underlyingAsset, address priceStrategy) EIP712('GSM', '1') {
    require(ghoToken != address(0), 'ZERO_ADDRESS_NOT_VALID');
    require(underlyingAsset != address(0), 'ZERO_ADDRESS_NOT_VALID');
    require(
      IGsmPriceStrategy(priceStrategy).UNDERLYING_ASSET() == underlyingAsset,
      'INVALID_PRICE_STRATEGY'
    );
    GHO_TOKEN = ghoToken;
    UNDERLYING_ASSET = underlyingAsset;
    PRICE_STRATEGY = priceStrategy;
  }

  /**
   * @notice GSM initializer
   * @param admin The address of the default admin role
   * @param ghoTreasury The address of the GHO treasury
   * @param exposureCap Maximum amount of user-supplied underlying asset in GSM
   */
  function initialize(
    address admin,
    address ghoTreasury,
    uint128 exposureCap
  ) external initializer {
    require(admin != address(0), 'ZERO_ADDRESS_NOT_VALID');
    _grantRole(DEFAULT_ADMIN_ROLE, admin);
    _grantRole(CONFIGURATOR_ROLE, admin);
    _updateGhoTreasury(ghoTreasury);
    _updateExposureCap(exposureCap);
  }

  /// @inheritdoc IGsm
  function buyAsset(
    uint256 minAmount,
    address receiver
  ) external notFrozen notSeized returns (uint256, uint256) {
    return _buyAsset(msg.sender, minAmount, receiver);
  }

  /// @inheritdoc IGsm
  function buyAssetWithSig(
    address originator,
    uint256 minAmount,
    address receiver,
    uint256 deadline,
    bytes calldata signature
  ) external notFrozen notSeized returns (uint256, uint256) {
    require(deadline >= block.timestamp, 'SIGNATURE_DEADLINE_EXPIRED');
    bytes32 digest = keccak256(
      abi.encode(
        '\x19\x01',
        _domainSeparatorV4(),
        BUY_ASSET_WITH_SIG_TYPEHASH,
        abi.encode(originator, minAmount, receiver, nonces[originator]++, deadline)
      )
    );
    require(
      SignatureChecker.isValidSignatureNow(originator, digest, signature),
      'SIGNATURE_INVALID'
    );

    return _buyAsset(originator, minAmount, receiver);
  }

  /// @inheritdoc IGsm
  function sellAsset(
    uint256 maxAmount,
    address receiver
  ) external notFrozen notSeized returns (uint256, uint256) {
    return _sellAsset(msg.sender, maxAmount, receiver);
  }

  /// @inheritdoc IGsm
  function sellAssetWithSig(
    address originator,
    uint256 maxAmount,
    address receiver,
    uint256 deadline,
    bytes calldata signature
  ) external notFrozen notSeized returns (uint256, uint256) {
    require(deadline >= block.timestamp, 'SIGNATURE_DEADLINE_EXPIRED');
    bytes32 digest = keccak256(
      abi.encode(
        '\x19\x01',
        _domainSeparatorV4(),
        SELL_ASSET_WITH_SIG_TYPEHASH,
        abi.encode(originator, maxAmount, receiver, nonces[originator]++, deadline)
      )
    );
    require(
      SignatureChecker.isValidSignatureNow(originator, digest, signature),
      'SIGNATURE_INVALID'
    );

    return _sellAsset(originator, maxAmount, receiver);
  }

  /// @inheritdoc IGsm
  function rescueTokens(
    address token,
    address to,
    uint256 amount
  ) external onlyRole(TOKEN_RESCUER_ROLE) {
    require(amount > 0, 'INVALID_AMOUNT');
    if (token == GHO_TOKEN) {
      uint256 rescuableBalance = IERC20(token).balanceOf(address(this)) - _accruedFees;
      require(rescuableBalance >= amount, 'INSUFFICIENT_GHO_TO_RESCUE');
    }
    if (token == UNDERLYING_ASSET) {
      uint256 rescuableBalance = IERC20(token).balanceOf(address(this)) - _currentExposure;
      require(rescuableBalance >= amount, 'INSUFFICIENT_EXOGENOUS_ASSET_TO_RESCUE');
    }
    IERC20(token).safeTransfer(to, amount);
    emit TokensRescued(token, to, amount);
  }

  /// @inheritdoc IGsm
  function setSwapFreeze(bool enable) external onlyRole(SWAP_FREEZER_ROLE) {
    if (enable) {
      require(!_isFrozen, 'GSM_ALREADY_FROZEN');
    } else {
      require(_isFrozen, 'GSM_ALREADY_UNFROZEN');
    }
    _isFrozen = enable;
    emit SwapFreeze(msg.sender, enable);
  }

  /// @inheritdoc IGsm
  function seize() external notSeized onlyRole(LIQUIDATOR_ROLE) returns (uint256) {
    _isSeized = true;
    _currentExposure = 0;
    _updateExposureCap(0);

    (, uint256 ghoMinted) = IGhoToken(GHO_TOKEN).getFacilitatorBucket(address(this));
    uint256 underlyingBalance = IERC20(UNDERLYING_ASSET).balanceOf(address(this));
    if (underlyingBalance > 0) {
      IERC20(UNDERLYING_ASSET).safeTransfer(_ghoTreasury, underlyingBalance);
    }

    emit Seized(msg.sender, _ghoTreasury, underlyingBalance, ghoMinted);
    return underlyingBalance;
  }

  /// @inheritdoc IGsm
  function burnAfterSeize(uint256 amount) external onlyRole(LIQUIDATOR_ROLE) returns (uint256) {
    require(_isSeized, 'GSM_NOT_SEIZED');
    require(amount > 0, 'INVALID_AMOUNT');

    (, uint256 ghoMinted) = IGhoToken(GHO_TOKEN).getFacilitatorBucket(address(this));
    if (amount > ghoMinted) {
      amount = ghoMinted;
    }
    IGhoToken(GHO_TOKEN).transferFrom(msg.sender, address(this), amount);
    IGhoToken(GHO_TOKEN).burn(amount);

    emit BurnAfterSeize(msg.sender, amount, (ghoMinted - amount));
    return amount;
  }

  /// @inheritdoc IGsm
  function updateFeeStrategy(address feeStrategy) external onlyRole(CONFIGURATOR_ROLE) {
    _updateFeeStrategy(feeStrategy);
  }

  /// @inheritdoc IGsm
  function updateExposureCap(uint128 exposureCap) external onlyRole(CONFIGURATOR_ROLE) {
    _updateExposureCap(exposureCap);
  }

  /// @inheritdoc IGhoFacilitator
  function distributeFeesToTreasury() public virtual override {
    uint256 accruedFees = _accruedFees;
    if (accruedFees > 0) {
      _accruedFees = 0;
      IERC20(GHO_TOKEN).transfer(_ghoTreasury, accruedFees);
      emit FeesDistributedToTreasury(_ghoTreasury, GHO_TOKEN, accruedFees);
    }
  }

  /// @inheritdoc IGhoFacilitator
  function updateGhoTreasury(address newGhoTreasury) external override onlyRole(CONFIGURATOR_ROLE) {
    _updateGhoTreasury(newGhoTreasury);
  }

  /// @inheritdoc IGsm
  function DOMAIN_SEPARATOR() external view returns (bytes32) {
    return _domainSeparatorV4();
  }

  /// @inheritdoc IGsm
  function getGhoAmountForBuyAsset(
    uint256 minAssetAmount
  ) external view returns (uint256, uint256, uint256, uint256) {
    return _calculateGhoAmountForBuyAsset(minAssetAmount);
  }

  /// @inheritdoc IGsm
  function getGhoAmountForSellAsset(
    uint256 maxAssetAmount
  ) external view returns (uint256, uint256, uint256, uint256) {
    return _calculateGhoAmountForSellAsset(maxAssetAmount);
  }

  /// @inheritdoc IGsm
  function getAssetAmountForBuyAsset(
    uint256 maxGhoAmount
  ) external view returns (uint256, uint256, uint256, uint256) {
    bool withFee = _feeStrategy != address(0);
    uint256 grossAmount = withFee
      ? IGsmFeeStrategy(_feeStrategy).getGrossAmountFromTotalBought(maxGhoAmount)
      : maxGhoAmount;
    // round down so maxGhoAmount is guaranteed
    uint256 assetAmount = IGsmPriceStrategy(PRICE_STRATEGY).getGhoPriceInAsset(grossAmount, false);
    uint256 finalGrossAmount = IGsmPriceStrategy(PRICE_STRATEGY).getAssetPriceInGho(
      assetAmount,
      true
    );
    uint256 finalFee = withFee ? IGsmFeeStrategy(_feeStrategy).getBuyFee(finalGrossAmount) : 0;
    return (assetAmount, finalGrossAmount + finalFee, finalGrossAmount, finalFee);
  }

  /// @inheritdoc IGsm
  function getAssetAmountForSellAsset(
    uint256 minGhoAmount
  ) external view returns (uint256, uint256, uint256, uint256) {
    bool withFee = _feeStrategy != address(0);
    uint256 grossAmount = withFee
      ? IGsmFeeStrategy(_feeStrategy).getGrossAmountFromTotalSold(minGhoAmount)
      : minGhoAmount;
    // round up so minGhoAmount is guaranteed
    uint256 assetAmount = IGsmPriceStrategy(PRICE_STRATEGY).getGhoPriceInAsset(grossAmount, true);
    uint256 finalGrossAmount = IGsmPriceStrategy(PRICE_STRATEGY).getAssetPriceInGho(
      assetAmount,
      false
    );
    uint256 finalFee = withFee ? IGsmFeeStrategy(_feeStrategy).getSellFee(finalGrossAmount) : 0;
    return (assetAmount, finalGrossAmount - finalFee, finalGrossAmount, finalFee);
  }

  /// @inheritdoc IGsm
  function getAvailableUnderlyingExposure() external view returns (uint256) {
    return _exposureCap > _currentExposure ? _exposureCap - _currentExposure : 0;
  }

  /// @inheritdoc IGsm
  function getExposureCap() external view returns (uint128) {
    return _exposureCap;
  }

  /// @inheritdoc IGsm
  function getAvailableLiquidity() external view returns (uint256) {
    return _currentExposure;
  }

  /// @inheritdoc IGsm
  function getFeeStrategy() external view returns (address) {
    return _feeStrategy;
  }

  /// @inheritdoc IGsm
  function getAccruedFees() external view returns (uint256) {
    return _accruedFees;
  }

  /// @inheritdoc IGsm
  function getIsFrozen() external view returns (bool) {
    return _isFrozen;
  }

  /// @inheritdoc IGsm
  function getIsSeized() external view returns (bool) {
    return _isSeized;
  }

  /// @inheritdoc IGsm
  function canSwap() external view returns (bool) {
    return !_isFrozen && !_isSeized;
  }

  /// @inheritdoc IGhoFacilitator
  function getGhoTreasury() external view override returns (address) {
    return _ghoTreasury;
  }

  /// @inheritdoc IGsm
  function GSM_REVISION() public pure virtual override returns (uint256) {
    return 1;
  }

  /**
   * @dev Buys an underlying asset with GHO
   * @param originator The originator of the request
   * @param minAmount The minimum amount of the underlying asset desired for purchase
   * @param receiver The recipient address of the underlying asset being purchased
   * @return The amount of underlying asset bought
   * @return The amount of GHO sold by the user
   */
  function _buyAsset(
    address originator,
    uint256 minAmount,
    address receiver
  ) internal returns (uint256, uint256) {
    (
      uint256 assetAmount,
      uint256 ghoSold,
      uint256 grossAmount,
      uint256 fee
    ) = _calculateGhoAmountForBuyAsset(minAmount);

    _beforeBuyAsset(originator, assetAmount, receiver);

    require(assetAmount > 0, 'INVALID_AMOUNT');
    require(_currentExposure >= assetAmount, 'INSUFFICIENT_AVAILABLE_EXOGENOUS_ASSET_LIQUIDITY');

    _currentExposure -= uint128(assetAmount);
    _accruedFees += fee.toUint128();
    IGhoToken(GHO_TOKEN).transferFrom(originator, address(this), ghoSold);
    IGhoToken(GHO_TOKEN).burn(grossAmount);
    IERC20(UNDERLYING_ASSET).safeTransfer(receiver, assetAmount);

    emit BuyAsset(originator, receiver, assetAmount, ghoSold, fee);
    return (assetAmount, ghoSold);
  }

  /**
   * @dev Hook that is called before `buyAsset`.
   * @dev This can be used to add custom logic
   * @param originator Originator of the request
   * @param amount The amount of the underlying asset desired for purchase
   * @param receiver Recipient address of the underlying asset being purchased
   */
  function _beforeBuyAsset(address originator, uint256 amount, address receiver) internal virtual {}

  /**
   * @dev Sells an underlying asset for GHO
   * @param originator The originator of the request
   * @param maxAmount The maximum amount of the underlying asset desired to sell
   * @param receiver The recipient address of the GHO being purchased
   * @return The amount of underlying asset sold
   * @return The amount of GHO bought by the user
   */
  function _sellAsset(
    address originator,
    uint256 maxAmount,
    address receiver
  ) internal returns (uint256, uint256) {
    (
      uint256 assetAmount,
      uint256 ghoBought,
      uint256 grossAmount,
      uint256 fee
    ) = _calculateGhoAmountForSellAsset(maxAmount);

    _beforeSellAsset(originator, assetAmount, receiver);

    require(assetAmount > 0, 'INVALID_AMOUNT');
    require(_currentExposure + assetAmount <= _exposureCap, 'EXOGENOUS_ASSET_EXPOSURE_TOO_HIGH');

    _currentExposure += uint128(assetAmount);
    _accruedFees += fee.toUint128();
    IERC20(UNDERLYING_ASSET).safeTransferFrom(originator, address(this), assetAmount);

    IGhoToken(GHO_TOKEN).mint(address(this), grossAmount);
    IGhoToken(GHO_TOKEN).transfer(receiver, ghoBought);

    emit SellAsset(originator, receiver, assetAmount, grossAmount, fee);
    return (assetAmount, ghoBought);
  }

  /**
   * @dev Hook that is called before `sellAsset`.
   * @dev This can be used to add custom logic
   * @param originator Originator of the request
   * @param amount The amount of the underlying asset desired to sell
   * @param receiver Recipient address of the GHO being purchased
   */
  function _beforeSellAsset(
    address originator,
    uint256 amount,
    address receiver
  ) internal virtual {}

  /**
   * @dev Returns the amount of GHO sold in exchange of buying underlying asset
   * @param assetAmount The amount of underlying asset to buy
   * @return The exact amount of asset the user purchases
   * @return The total amount of GHO the user sells (gross amount in GHO plus fee)
   * @return The gross amount of GHO
   * @return The fee amount in GHO, applied on top of gross amount of GHO
   */
  function _calculateGhoAmountForBuyAsset(
    uint256 assetAmount
  ) internal view returns (uint256, uint256, uint256, uint256) {
    bool withFee = _feeStrategy != address(0);
    // pick the highest GHO amount possible for given asset amount
    uint256 grossAmount = IGsmPriceStrategy(PRICE_STRATEGY).getAssetPriceInGho(assetAmount, true);
    uint256 fee = withFee ? IGsmFeeStrategy(_feeStrategy).getBuyFee(grossAmount) : 0;
    uint256 ghoSold = grossAmount + fee;
    uint256 finalGrossAmount = withFee
      ? IGsmFeeStrategy(_feeStrategy).getGrossAmountFromTotalBought(ghoSold)
      : ghoSold;
    // pick the lowest asset amount possible for given GHO amount
    uint256 finalAssetAmount = IGsmPriceStrategy(PRICE_STRATEGY).getGhoPriceInAsset(
      finalGrossAmount,
      false
    );
    uint256 finalFee = ghoSold - finalGrossAmount;
    return (finalAssetAmount, finalGrossAmount + finalFee, finalGrossAmount, finalFee);
  }

  /**
   * @dev Returns the amount of GHO bought in exchange of a given amount of underlying asset
   * @param assetAmount The amount of underlying asset to sell
   * @return The exact amount of asset the user sells
   * @return The total amount of GHO the user buys (gross amount in GHO minus fee)
   * @return The gross amount of GHO
   * @return The fee amount in GHO, applied to the gross amount of GHO
   */
  function _calculateGhoAmountForSellAsset(
    uint256 assetAmount
  ) internal view returns (uint256, uint256, uint256, uint256) {
    bool withFee = _feeStrategy != address(0);
    // pick the lowest GHO amount possible for given asset amount
    uint256 grossAmount = IGsmPriceStrategy(PRICE_STRATEGY).getAssetPriceInGho(assetAmount, false);
    uint256 fee = withFee ? IGsmFeeStrategy(_feeStrategy).getSellFee(grossAmount) : 0;
    uint256 ghoBought = grossAmount - fee;
    uint256 finalGrossAmount = withFee
      ? IGsmFeeStrategy(_feeStrategy).getGrossAmountFromTotalSold(ghoBought)
      : ghoBought;
    // pick the highest asset amount possible for given GHO amount
    uint256 finalAssetAmount = IGsmPriceStrategy(PRICE_STRATEGY).getGhoPriceInAsset(
      finalGrossAmount,
      true
    );
    uint256 finalFee = finalGrossAmount - ghoBought;
    return (finalAssetAmount, finalGrossAmount - finalFee, finalGrossAmount, finalFee);
  }

  /**
   * @dev Updates Fee Strategy
   * @param feeStrategy The address of the new Fee Strategy
   */
  function _updateFeeStrategy(address feeStrategy) internal {
    address oldFeeStrategy = _feeStrategy;
    _feeStrategy = feeStrategy;
    emit FeeStrategyUpdated(oldFeeStrategy, feeStrategy);
  }

  /**
   * @dev Updates Exposure Cap
   * @param exposureCap The value of the new Exposure Cap
   */
  function _updateExposureCap(uint128 exposureCap) internal {
    uint128 oldExposureCap = _exposureCap;
    _exposureCap = exposureCap;
    emit ExposureCapUpdated(oldExposureCap, exposureCap);
  }

  /**
   * @dev Updates GHO Treasury Address
   * @param newGhoTreasury The address of the new GHO Treasury
   */
  function _updateGhoTreasury(address newGhoTreasury) internal {
    require(newGhoTreasury != address(0), 'ZERO_ADDRESS_NOT_VALID');
    address oldGhoTreasury = _ghoTreasury;
    _ghoTreasury = newGhoTreasury;
    emit GhoTreasuryUpdated(oldGhoTreasury, newGhoTreasury);
  }

  /// @inheritdoc VersionedInitializable
  function getRevision() internal pure virtual override returns (uint256) {
    return GSM_REVISION();
  }
}

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

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

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

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);
}

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

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import {IAccessControl} from '@openzeppelin/contracts/access/IAccessControl.sol';
import {IGhoFacilitator} from '../../../gho/interfaces/IGhoFacilitator.sol';

/**
 * @title IGsm
 * @author Aave
 * @notice Defines the behaviour of a GHO Stability Module
 */
interface IGsm is IAccessControl, IGhoFacilitator {
  /**
   * @dev Emitted when a user buys an asset (selling GHO) in the GSM
   * @param originator The address of the buyer originating the request
   * @param receiver The address of the receiver of the underlying asset
   * @param underlyingAmount The amount of the underlying asset bought
   * @param ghoAmount The amount of GHO sold, inclusive of fee
   * @param fee The fee paid by the buyer, in GHO
   */
  event BuyAsset(
    address indexed originator,
    address indexed receiver,
    uint256 underlyingAmount,
    uint256 ghoAmount,
    uint256 fee
  );

  /**
   * @dev Emitted when a user sells an asset (buying GHO) in the GSM
   * @param originator The address of the seller originating the request
   * @param receiver The address of the receiver of GHO
   * @param underlyingAmount The amount of the underlying asset sold
   * @param ghoAmount The amount of GHO bought, inclusive of fee
   * @param fee The fee paid by the buyer, in GHO
   */
  event SellAsset(
    address indexed originator,
    address indexed receiver,
    uint256 underlyingAmount,
    uint256 ghoAmount,
    uint256 fee
  );

  /**
   * @dev Emitted when the Swap Freezer freezes buys/sells
   * @param freezer The address of the Swap Freezer
   * @param enabled True if swap functions are frozen, False otherwise
   */
  event SwapFreeze(address indexed freezer, bool enabled);

  /**
   * @dev Emitted when a Liquidator seizes GSM funds
   * @param seizer The address originating the seizure request
   * @param recipient The address of the recipient of seized funds
   * @param underlyingAmount The amount of the underlying asset seized
   * @param ghoOutstanding The amount of remaining GHO that the GSM had minted
   */
  event Seized(
    address indexed seizer,
    address indexed recipient,
    uint256 underlyingAmount,
    uint256 ghoOutstanding
  );

  /**
   * @dev Emitted when burning GHO after a seizure of GSM funds
   * @param burner The address of the burner
   * @param amount The amount of GHO burned
   * @param ghoOutstanding The amount of remaining GHO that the GSM had minted
   */
  event BurnAfterSeize(address indexed burner, uint256 amount, uint256 ghoOutstanding);

  /**
   * @dev Emitted when the Fee Strategy is updated
   * @param oldFeeStrategy The address of the old Fee Strategy
   * @param newFeeStrategy The address of the new Fee Strategy
   */
  event FeeStrategyUpdated(address indexed oldFeeStrategy, address indexed newFeeStrategy);

  /**
   * @dev Emitted when the GSM underlying asset Exposure Cap is updated
   * @param oldExposureCap The amount of the old Exposure Cap
   * @param newExposureCap The amount of the new Exposure Cap
   */
  event ExposureCapUpdated(uint256 oldExposureCap, uint256 newExposureCap);

  /**
   * @dev Emitted when tokens are rescued from the GSM
   * @param tokenRescued The address of the rescued token
   * @param recipient The address that received the rescued tokens
   * @param amountRescued The amount of token rescued
   */
  event TokensRescued(
    address indexed tokenRescued,
    address indexed recipient,
    uint256 amountRescued
  );

  /**
   * @notice Buys the GSM underlying asset in exchange for selling GHO
   * @dev Use `getAssetAmountForBuyAsset` function to calculate the amount based on the GHO amount to sell
   * @param minAmount The minimum amount of the underlying asset to buy
   * @param receiver Recipient address of the underlying asset being purchased
   * @return The amount of underlying asset bought
   * @return The amount of GHO sold by the user
   */
  function buyAsset(uint256 minAmount, address receiver) external returns (uint256, uint256);

  /**
   * @notice Buys the GSM underlying asset in exchange for selling GHO, using an EIP-712 signature
   * @dev Use `getAssetAmountForBuyAsset` function to calculate the amount based on the GHO amount to sell
   * @param originator The signer of the request
   * @param minAmount The minimum amount of the underlying asset to buy
   * @param receiver Recipient address of the underlying asset being purchased
   * @param deadline Signature expiration deadline
   * @param signature Signature data
   * @return The amount of underlying asset bought
   * @return The amount of GHO sold by the user
   */
  function buyAssetWithSig(
    address originator,
    uint256 minAmount,
    address receiver,
    uint256 deadline,
    bytes calldata signature
  ) external returns (uint256, uint256);

  /**
   * @notice Sells the GSM underlying asset in exchange for buying GHO
   * @dev Use `getAssetAmountForSellAsset` function to calculate the amount based on the GHO amount to buy
   * @param maxAmount The maximum amount of the underlying asset to sell
   * @param receiver Recipient address of the GHO being purchased
   * @return The amount of underlying asset sold
   * @return The amount of GHO bought by the user
   */
  function sellAsset(uint256 maxAmount, address receiver) external returns (uint256, uint256);

  /**
   * @notice Sells the GSM underlying asset in exchange for buying GHO, using an EIP-712 signature
   * @dev Use `getAssetAmountForSellAsset` function to calculate the amount based on the GHO amount to buy
   * @param originator The signer of the request
   * @param maxAmount The maximum amount of the underlying asset to sell
   * @param receiver Recipient address of the GHO being purchased
   * @param deadline Signature expiration deadline
   * @param signature Signature data
   * @return The amount of underlying asset sold
   * @return The amount of GHO bought by the user
   */
  function sellAssetWithSig(
    address originator,
    uint256 maxAmount,
    address receiver,
    uint256 deadline,
    bytes calldata signature
  ) external returns (uint256, uint256);

  /**
   * @notice Rescue and transfer tokens locked in this contract
   * @param token The address of the token
   * @param to The address of the recipient
   * @param amount The amount of token to transfer
   */
  function rescueTokens(address token, address to, uint256 amount) external;

  /**
   * @notice Enable or disable the swap freeze
   * @param enable True to freeze swap functions, false otherwise
   */
  function setSwapFreeze(bool enable) external;

  /**
   * @notice Seizes all of the underlying asset from the GSM, sending to the Treasury
   * @dev Seizing is a last resort mechanism to provide the Treasury with the entire amount of underlying asset
   * so it can be used to backstop any potential event impacting the functionality of the Gsm.
   * @dev Seizing disables the swap feature
   * @return The amount of underlying asset seized and transferred to Treasury
   */
  function seize() external returns (uint256);

  /**
   * @notice Burns an amount of GHO after seizure reducing the facilitator bucket level effectively
   * @dev Passing an amount higher than the facilitator bucket level will result in burning all minted GHO
   * @dev Only callable if the GSM has assets seized, helpful to wind down the facilitator
   * @param amount The amount of GHO to burn
   * @return The amount of GHO burned
   */
  function burnAfterSeize(uint256 amount) external returns (uint256);

  /**
   * @notice Updates the address of the Fee Strategy
   * @param feeStrategy The address of the new FeeStrategy
   */
  function updateFeeStrategy(address feeStrategy) external;

  /**
   * @notice Updates the exposure cap of the underlying asset
   * @param exposureCap The new value for the exposure cap (in underlying asset terms)
   */
  function updateExposureCap(uint128 exposureCap) external;

  /**
   * @notice Returns the EIP712 domain separator
   * @return The EIP712 domain separator
   */
  function DOMAIN_SEPARATOR() external view returns (bytes32);

  /**
   * @notice Returns the total amount of GHO, gross amount and fee result of buying assets
   * @param minAssetAmount The minimum amount of underlying asset to buy
   * @return The exact amount of underlying asset to be bought
   * @return The total amount of GHO the user sells (gross amount in GHO plus fee)
   * @return The gross amount of GHO
   * @return The fee amount in GHO, applied on top of gross amount of GHO
   */
  function getGhoAmountForBuyAsset(
    uint256 minAssetAmount
  ) external view returns (uint256, uint256, uint256, uint256);

  /**
   * @notice Returns the total amount of GHO, gross amount and fee result of selling assets
   * @param maxAssetAmount The maximum amount of underlying asset to sell
   * @return The exact amount of underlying asset to sell
   * @return The total amount of GHO the user buys (gross amount in GHO minus fee)
   * @return The gross amount of GHO
   * @return The fee amount in GHO, applied to the gross amount of GHO
   */
  function getGhoAmountForSellAsset(
    uint256 maxAssetAmount
  ) external view returns (uint256, uint256, uint256, uint256);

  /**
   * @notice Returns the amount of underlying asset, gross amount of GHO and fee result of buying assets
   * @param maxGhoAmount The maximum amount of GHO the user provides for buying underlying asset
   * @return The amount of underlying asset the user buys
   * @return The exact amount of GHO the user provides
   * @return The gross amount of GHO corresponding to the given total amount of GHO
   * @return The fee amount in GHO, charged for buying assets
   */
  function getAssetAmountForBuyAsset(
    uint256 maxGhoAmount
  ) external view returns (uint256, uint256, uint256, uint256);

  /**
   * @notice Returns the amount of underlying asset, gross amount of GHO and fee result of selling assets
   * @param minGhoAmount The minimum amount of GHO the user must receive for selling underlying asset
   * @return The amount of underlying asset the user sells
   * @return The exact amount of GHO the user receives in exchange
   * @return The gross amount of GHO corresponding to the given total amount of GHO
   * @return The fee amount in GHO, charged for selling assets
   */
  function getAssetAmountForSellAsset(
    uint256 minGhoAmount
  ) external view returns (uint256, uint256, uint256, uint256);

  /**
   * @notice Returns the remaining GSM exposure capacity
   * @return The amount of underlying asset that can be sold to the GSM
   */
  function getAvailableUnderlyingExposure() external view returns (uint256);

  /**
   * @notice Returns the exposure limit to the underlying asset
   * @return The maximum amount of underlying asset that can be sold to the GSM
   */
  function getExposureCap() external view returns (uint128);

  /**
   * @notice Returns the actual underlying asset balance immediately available in the GSM
   * @return The amount of underlying asset that can be bought from the GSM
   */
  function getAvailableLiquidity() external view returns (uint256);

  /**
   * @notice Returns the Fee Strategy for the GSM
   * @dev It returns 0x0 in case of no fee strategy
   * @return The address of the FeeStrategy
   */
  function getFeeStrategy() external view returns (address);

  /**
   * @notice Returns the amount of current accrued fees
   * @dev It does not factor in potential fees that can be accrued upon distribution of fees
   * @return The amount of accrued fees
   */
  function getAccruedFees() external view returns (uint256);

  /**
   * @notice Returns the freeze status of the GSM
   * @return True if frozen, false if not
   */
  function getIsFrozen() external view returns (bool);

  /**
   * @notice Returns the current seizure status of the GSM
   * @return True if the GSM has been seized, false if not
   */
  function getIsSeized() external view returns (bool);

  /**
   * @notice Returns whether or not swaps via buyAsset/sellAsset are currently possible
   * @return True if the GSM has swapping enabled, false otherwise
   */
  function canSwap() external view returns (bool);

  /**
   * @notice Returns the GSM revision number
   * @return The revision number
   */
  function GSM_REVISION() external pure returns (uint256);

  /**
   * @notice Returns the address of the GHO token
   * @return The address of GHO token contract
   */
  function GHO_TOKEN() external view returns (address);

  /**
   * @notice Returns the underlying asset of the GSM
   * @return The address of the underlying asset
   */
  function UNDERLYING_ASSET() external view returns (address);

  /**
   * @notice Returns the price strategy of the GSM
   * @return The address of the price strategy
   */
  function PRICE_STRATEGY() external view returns (address);

  /**
   * @notice Returns the current nonce (for EIP-712 signature methods) of an address
   * @param user The address of the user
   * @return The current nonce of the user
   */
  function nonces(address user) external view returns (uint256);

  /**
   * @notice Returns the identifier of the Configurator Role
   * @return The bytes32 id hash of the Configurator role
   */
  function CONFIGURATOR_ROLE() external pure returns (bytes32);

  /**
   * @notice Returns the identifier of the Token Rescuer Role
   * @return The bytes32 id hash of the TokenRescuer role
   */
  function TOKEN_RESCUER_ROLE() external pure returns (bytes32);

  /**
   * @notice Returns the identifier of the Swap Freezer Role
   * @return The bytes32 id hash of the SwapFreezer role
   */
  function SWAP_FREEZER_ROLE() external pure returns (bytes32);

  /**
   * @notice Returns the identifier of the Liquidator Role
   * @return The bytes32 id hash of the Liquidator role
   */
  function LIQUIDATOR_ROLE() external pure returns (bytes32);

  /**
   * @notice Returns the EIP-712 signature typehash for buyAssetWithSig
   * @return The bytes32 signature typehash for buyAssetWithSig
   */
  function BUY_ASSET_WITH_SIG_TYPEHASH() external pure returns (bytes32);

  /**
   * @notice Returns the EIP-712 signature typehash for sellAssetWithSig
   * @return The bytes32 signature typehash for sellAssetWithSig
   */
  function SELL_ASSET_WITH_SIG_TYPEHASH() external pure returns (bytes32);
}

// SPDX-License-Identifier: AGPL-3.0
pragma solidity 0.8.10;

/**
 * @title VersionedInitializable
 * @author Aave, inspired by the OpenZeppelin Initializable contract
 * @notice Helper contract to implement initializer functions. To use it, replace
 * the constructor with a function that has the `initializer` modifier.
 * @dev WARNING: Unlike constructors, initializer functions must be manually
 * invoked. This applies both to deploying an Initializable contract, as well
 * as extending an Initializable contract via inheritance.
 * WARNING: When used with inheritance, manual care must be taken to not invoke
 * a parent initializer twice, or ensure that all initializers are idempotent,
 * because this is not dealt with automatically as with constructors.
 */
abstract contract VersionedInitializable {
  /**
   * @dev Indicates that the contract has been initialized.
   */
  uint256 private lastInitializedRevision = 0;

  /**
   * @dev Indicates that the contract is in the process of being initialized.
   */
  bool private initializing;

  /**
   * @dev Modifier to use in the initializer function of a contract.
   */
  modifier initializer() {
    uint256 revision = getRevision();
    require(
      initializing || isConstructor() || revision > lastInitializedRevision,
      'Contract instance has already been initialized'
    );

    bool isTopLevelCall = !initializing;
    if (isTopLevelCall) {
      initializing = true;
      lastInitializedRevision = revision;
    }

    _;

    if (isTopLevelCall) {
      initializing = false;
    }
  }

  /**
   * @notice Returns the revision number of the contract
   * @dev Needs to be defined in the inherited class as a constant.
   * @return The revision number
   */
  function getRevision() internal pure virtual returns (uint256);

  /**
   * @notice Returns true if and only if the function is running in the constructor
   * @return True if the function is running in the constructor
   */
  function isConstructor() private view returns (bool) {
    // extcodesize checks the size of the code stored in an address, and
    // address returns the current address. Since the code is still not
    // deployed when running a constructor, any checks on its code size will
    // yield zero, making it an effective way to detect if a contract is
    // under construction or not.
    uint256 cs;
    //solium-disable-next-line
    assembly {
      cs := extcodesize(address())
    }
    return cs == 0;
  }

  // Reserved storage space to allow for layout changes in the future.
  uint256[50] private ______gap;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/cryptography/EIP712.sol)

pragma solidity ^0.8.0;

import "./ECDSA.sol";

/**
 * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
 *
 * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
 * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
 * they need in their contracts using a combination of `abi.encode` and `keccak256`.
 *
 * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
 * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
 * ({_hashTypedDataV4}).
 *
 * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
 * the chain id to protect against replay attacks on an eventual fork of the chain.
 *
 * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
 * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
 *
 * _Available since v3.4._
 */
abstract contract EIP712 {
    /* solhint-disable var-name-mixedcase */
    // Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
    // invalidate the cached domain separator if the chain id changes.
    bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
    uint256 private immutable _CACHED_CHAIN_ID;
    address private immutable _CACHED_THIS;

    bytes32 private immutable _HASHED_NAME;
    bytes32 private immutable _HASHED_VERSION;
    bytes32 private immutable _TYPE_HASH;

    /* solhint-enable var-name-mixedcase */

    /**
     * @dev Initializes the domain separator and parameter caches.
     *
     * The meaning of `name` and `version` is specified in
     * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
     *
     * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
     * - `version`: the current major version of the signing domain.
     *
     * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
     * contract upgrade].
     */
    constructor(string memory name, string memory version) {
        bytes32 hashedName = keccak256(bytes(name));
        bytes32 hashedVersion = keccak256(bytes(version));
        bytes32 typeHash = keccak256(
            "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
        );
        _HASHED_NAME = hashedName;
        _HASHED_VERSION = hashedVersion;
        _CACHED_CHAIN_ID = block.chainid;
        _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(typeHash, hashedName, hashedVersion);
        _CACHED_THIS = address(this);
        _TYPE_HASH = typeHash;
    }

    /**
     * @dev Returns the domain separator for the current chain.
     */
    function _domainSeparatorV4() internal view returns (bytes32) {
        if (address(this) == _CACHED_THIS && block.chainid == _CACHED_CHAIN_ID) {
            return _CACHED_DOMAIN_SEPARATOR;
        } else {
            return _buildDomainSeparator(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION);
        }
    }

    function _buildDomainSeparator(
        bytes32 typeHash,
        bytes32 nameHash,
        bytes32 versionHash
    ) private view returns (bytes32) {
        return keccak256(abi.encode(typeHash, nameHash, versionHash, block.chainid, address(this)));
    }

    /**
     * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
     * function returns the hash of the fully encoded EIP712 message for this domain.
     *
     * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
     *
     * ```solidity
     * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
     *     keccak256("Mail(address to,string contents)"),
     *     mailTo,
     *     keccak256(bytes(mailContents))
     * )));
     * address signer = ECDSA.recover(digest, signature);
     * ```
     */
    function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
        return ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/cryptography/SignatureChecker.sol)

pragma solidity ^0.8.0;

import "./ECDSA.sol";
import "../Address.sol";
import "../../interfaces/IERC1271.sol";

/**
 * @dev Signature verification helper that can be used instead of `ECDSA.recover` to seamlessly support both ECDSA
 * signatures from externally owned accounts (EOAs) as well as ERC1271 signatures from smart contract wallets like
 * Argent and Gnosis Safe.
 *
 * _Available since v4.1._
 */
library SignatureChecker {
    /**
     * @dev Checks if a signature is valid for a given signer and data hash. If the signer is a smart contract, the
     * signature is validated against that smart contract using ERC1271, otherwise it's validated using `ECDSA.recover`.
     *
     * NOTE: Unlike ECDSA signatures, contract signatures are revocable, and the outcome of this function can thus
     * change through time. It could return true at block N and false at block N+1 (or the opposite).
     */
    function isValidSignatureNow(
        address signer,
        bytes32 hash,
        bytes memory signature
    ) internal view returns (bool) {
        (address recovered, ECDSA.RecoverError error) = ECDSA.tryRecover(hash, signature);
        if (error == ECDSA.RecoverError.NoError && recovered == signer) {
            return true;
        }

        (bool success, bytes memory result) = signer.staticcall(
            abi.encodeWithSelector(IERC1271.isValidSignature.selector, hash, signature)
        );
        return (success &&
            result.length == 32 &&
            abi.decode(result, (bytes32)) == bytes32(IERC1271.isValidSignature.selector));
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (access/AccessControl.sol)

pragma solidity ^0.8.0;

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

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

    mapping(bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

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

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

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

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

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

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

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

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

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

        _revokeRole(role, account);
    }

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

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

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

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

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/**
 * @title IGsmFeeStrategy
 * @author Aave
 * @notice Defines the behaviour of Fee Strategies
 * @dev Functions' logic must be invertible, being possible to calculate the fee amount based on the gross amount, and
 * the other way round.
 * @dev All math operations must round up, favoring the protocol.
 */
interface IGsmFeeStrategy {
  /**
   * @notice Returns the fee to be applied when buying an underlying asset in exchange for GHO
   * @param grossAmount The amount of GHO being sold for the underlying asset
   * @return The fee amount of GHO
   */
  function getBuyFee(uint256 grossAmount) external view returns (uint256);

  /**
   * @notice Returns the fee to be applied when buying GHO in exchange for an underlying asset
   * @param grossAmount The amount of underlying, converted to GHO, being sold
   * @return The fee amount of GHO
   */
  function getSellFee(uint256 grossAmount) external view returns (uint256);

  /**
   * @notice Returns the gross amount of GHO being bought based on the total bought amount
   * @param totalAmount The total amount of GHO being bought (gross amount, GHO bought plus fee)
   * @return The gross amount of GHO being bought (total amount minus fee)
   */
  function getGrossAmountFromTotalBought(uint256 totalAmount) external view returns (uint256);

  /**
   * @notice Returns the amount of GHO being sold based on the total sold amount
   * @param totalAmount The total amount of GHO being sold (gross amount, GHO sold minus fee)
   * @return The gross amount of GHO being sold (total amount plus fee)
   */
  function getGrossAmountFromTotalSold(uint256 totalAmount) external view returns (uint256);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/cryptography/ECDSA.sol)

pragma solidity ^0.8.0;

import "../Strings.sol";

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    enum RecoverError {
        NoError,
        InvalidSignature,
        InvalidSignatureLength,
        InvalidSignatureS,
        InvalidSignatureV // Deprecated in v4.8
    }

    function _throwError(RecoverError error) private pure {
        if (error == RecoverError.NoError) {
            return; // no error: do nothing
        } else if (error == RecoverError.InvalidSignature) {
            revert("ECDSA: invalid signature");
        } else if (error == RecoverError.InvalidSignatureLength) {
            revert("ECDSA: invalid signature length");
        } else if (error == RecoverError.InvalidSignatureS) {
            revert("ECDSA: invalid signature 's' value");
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature` or error string. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     *
     * Documentation for signature generation:
     * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
     * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
     *
     * _Available since v4.3._
     */
    function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
        if (signature.length == 65) {
            bytes32 r;
            bytes32 s;
            uint8 v;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            /// @solidity memory-safe-assembly
            assembly {
                r := mload(add(signature, 0x20))
                s := mload(add(signature, 0x40))
                v := byte(0, mload(add(signature, 0x60)))
            }
            return tryRecover(hash, v, r, s);
        } else {
            return (address(0), RecoverError.InvalidSignatureLength);
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, signature);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
     *
     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address, RecoverError) {
        bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
        uint8 v = uint8((uint256(vs) >> 255) + 27);
        return tryRecover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
     *
     * _Available since v4.2._
     */
    function recover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, r, vs);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
     * `r` and `s` signature fields separately.
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address, RecoverError) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return (address(0), RecoverError.InvalidSignatureS);
        }

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        if (signer == address(0)) {
            return (address(0), RecoverError.InvalidSignature);
        }

        return (signer, RecoverError.NoError);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from `s`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
    }

    /**
     * @dev Returns an Ethereum Signed Typed Data, created from a
     * `domainSeparator` and a `structHash`. This produces hash corresponding
     * to the one signed with the
     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
     * JSON-RPC method as part of EIP-712.
     *
     * See {recover}.
     */
    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)

pragma solidity ^0.8.1;

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

        return account.code.length > 0;
    }

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

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

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

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

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

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

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

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

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

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) 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(errorMessage);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (interfaces/IERC1271.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC1271 standard signature validation method for
 * contracts as defined in https://eips.ethereum.org/EIPS/eip-1271[ERC-1271].
 *
 * _Available since v4.1._
 */
interface IERC1271 {
    /**
     * @dev Should return whether the signature provided is valid for the provided data
     * @param hash      Hash of the data to be signed
     * @param signature Signature byte array associated with _data
     */
    function isValidSignature(bytes32 hash, bytes memory signature) external view returns (bytes4 magicValue);
}

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

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

import "./math/Math.sol";

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

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = Math.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            /// @solidity memory-safe-assembly
            assembly {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                /// @solidity memory-safe-assembly
                assembly {
                    mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, Math.log256(value) + 1);
        }
    }

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

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

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

pragma solidity ^0.8.0;

import "./IERC165.sol";

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    enum Rounding {
        Down, // Toward negative infinity
        Up, // Toward infinity
        Zero // Toward zero
    }

    /**
     * @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 up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (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; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod0 := mul(x, y)
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            require(denominator > prod1);

            ///////////////////////////////////////////////
            // 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.

            // Does not overflow because the denominator cannot be zero at this stage in the function.
            uint256 twos = denominator & (~denominator + 1);
            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 (rounding == Rounding.Up && 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 down.
     *
     * 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 + (rounding == Rounding.Up && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2, rounded down, of a positive value.
     * 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 + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10, rounded down, of a positive value.
     * 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 + (rounding == Rounding.Up && 10**result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256, rounded down, of a positive value.
     * 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 10, 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 + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);
        }
    }
}

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

pragma solidity ^0.8.0;

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