Cryo Explorer Ethereum Mainnet

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

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

interface IPCV {

    // --- Events --
    event THUSDTokenAddressSet(address _thusdTokenAddress);
    event BorrowerOperationsAddressSet(address _borrowerOperationsAddress);
    event CollateralAddressSet(address _collateralAddress);
    event BAMMAddressSet(address _bammAddress);
    event RolesSet(address _council, address _treasury);

    event BAMMDeposit(uint256 _thusdAmount);
    event BAMMWithdraw(uint256 _numShares);
    event THUSDWithdraw(address _recipient, uint256 _thusdAmount);
    event CollateralWithdraw(address _recipient, uint256 _collateralAmount);

    event PCVDebtPaid(uint256 _paidDebt);
    
    event RecipientAdded(address _recipient);
    event RecipientRemoved(address _recipient);

    // --- Functions ---

    function debtToPay() external returns(uint256);
    function payDebt(uint256 _thusdToBurn) external;

    function setAddresses(
        address _thusdTokenAddress, 
        address _borrowerOperations, 
        address payable _bammAddress,
        address _collateralERC20
    ) external;
    function initialize() external;

    function depositToBAMM(uint256 _thusdAmount) external;
    function withdrawFromBAMM(uint256 _numShares) external;
    function withdrawTHUSD(address _recipient, uint256 _thusdAmount) external;
    function withdrawCollateral(address _recipient, uint256 _collateralAmount) external;

    function addRecipientToWhitelist(address _recipient) external;
    function addRecipientsToWhitelist(address[] calldata _recipients) external;
    function removeRecipientFromWhitelist(address _recipient) external;
    function removeRecipientsFromWhitelist(address[] calldata _recipients) external;

    function startChangingRoles(address _council, address _treasury) external;
    function cancelChangingRoles() external;
    function finalizeChangingRoles() external;
    
    function collateralERC20() external view returns(IERC20);
    function thusdToken() external view returns(ITHUSDToken);

}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

// Common interface for the Pools.
interface IPool {

    // --- Events ---

    event CollateralBalanceUpdated(uint256 _newBalance);
    event THUSDBalanceUpdated(uint256 _newBalance);
    event ActivePoolAddressChanged(address _newActivePoolAddress);
    event DefaultPoolAddressChanged(address _newDefaultPoolAddress);
    event StabilityPoolAddressChanged(address _newStabilityPoolAddress);
    event CollateralSent(address _to, uint256 _amount);

    // --- Functions ---

    function getCollateralBalance() external view returns (uint);

    function getTHUSDDebt() external view returns (uint);

    function increaseTHUSDDebt(uint256 _amount) external;

    function decreaseTHUSDDebt(uint256 _amount) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

import "./Interfaces/IBorrowerOperations.sol";
import "./Interfaces/ITroveManager.sol";
import "./Interfaces/ITHUSDToken.sol";
import "./Interfaces/ICollSurplusPool.sol";
import "./Interfaces/ISortedTroves.sol";
import "./Interfaces/IPCV.sol";
import "./Dependencies/LiquityBase.sol";
import "./Dependencies/Ownable.sol";
import "./Dependencies/CheckContract.sol";
import "./Dependencies/SendCollateral.sol";

contract BorrowerOperations is LiquityBase, Ownable, CheckContract, SendCollateral, IBorrowerOperations {

    string constant public NAME = "BorrowerOperations";

    // --- Connected contract declarations ---

    ITroveManager public troveManager;

    address public collateralAddress;
    address public gasPoolAddress;
    address public pcvAddress;
    address public stabilityPoolAddress;

    ICollSurplusPool collSurplusPool;

    ITHUSDToken public thusdToken;

    // A doubly linked list of Troves, sorted by their collateral ratios
    ISortedTroves public sortedTroves;

    /* --- Variable container structs  ---

    Used to hold, return and assign variables inside a function, in order to avoid the error:
    "CompilerError: Stack too deep". */

    struct LocalVariables_adjustTrove {
        uint256 price;
        uint256 collChange;
        uint256 netDebtChange;
        bool isCollIncrease;
        uint256 debt;
        uint256 coll;
        uint256 oldICR;
        uint256 newICR;
        uint256 newTCR;
        uint256 THUSDFee;
        uint256 newDebt;
        uint256 newColl;
        uint256 stake;
    }

    struct LocalVariables_openTrove {
        uint256 price;
        uint256 THUSDFee;
        uint256 netDebt;
        uint256 compositeDebt;
        uint256 ICR;
        uint256 NICR;
        uint256 stake;
        uint256 arrayIndex;
    }

    struct ContractsCache {
        ITroveManager troveManager;
        IActivePool activePool;
        ITHUSDToken thusdToken;
    }

    enum BorrowerOperation {
        openTrove,
        closeTrove,
        adjustTrove
    }

    event TroveUpdated(address indexed _borrower, uint256 _debt, uint256 _coll, uint256 stake, BorrowerOperation operation);
    // --- Dependency setters ---

    function setAddresses(
        address _troveManagerAddress,
        address _activePoolAddress,
        address _defaultPoolAddress,
        address _stabilityPoolAddress,
        address _gasPoolAddress,
        address _collSurplusPoolAddress,
        address _priceFeedAddress,
        address _sortedTrovesAddress,
        address _thusdTokenAddress,
        address _pcvAddress,
        address _collateralAddress
    )
        external
        override
        onlyOwner
    {
        // This makes impossible to open a trove with zero withdrawn THUSD
        assert(MIN_NET_DEBT > 0);

        checkContract(_troveManagerAddress);
        checkContract(_activePoolAddress);
        checkContract(_defaultPoolAddress);
        checkContract(_stabilityPoolAddress);
        checkContract(_gasPoolAddress);
        checkContract(_collSurplusPoolAddress);
        checkContract(_priceFeedAddress);
        checkContract(_sortedTrovesAddress);
        checkContract(_thusdTokenAddress);
        checkContract(_pcvAddress);
        if (_collateralAddress != address(0)) {
            checkContract(_collateralAddress);
        }

        troveManager = ITroveManager(_troveManagerAddress);
        activePool = IActivePool(_activePoolAddress);
        defaultPool = IDefaultPool(_defaultPoolAddress);
        stabilityPoolAddress = _stabilityPoolAddress;
        gasPoolAddress = _gasPoolAddress;
        collSurplusPool = ICollSurplusPool(_collSurplusPoolAddress);
        priceFeed = IPriceFeed(_priceFeedAddress);
        sortedTroves = ISortedTroves(_sortedTrovesAddress);
        thusdToken = ITHUSDToken(_thusdTokenAddress);
        pcvAddress = _pcvAddress;
        collateralAddress = _collateralAddress;
        
        require(
            (Ownable(_defaultPoolAddress).owner() != address(0) || 
            defaultPool.collateralAddress() == _collateralAddress) &&
            (Ownable(_activePoolAddress).owner() != address(0) || 
            activePool.collateralAddress() == _collateralAddress) &&
            (Ownable(_stabilityPoolAddress).owner() != address(0) || 
            IStabilityPool(stabilityPoolAddress).collateralAddress() == _collateralAddress) &&
            (Ownable(_collSurplusPoolAddress).owner() != address(0) || 
            collSurplusPool.collateralAddress() == _collateralAddress) &&
            (address(IPCV(pcvAddress).thusdToken()) == address(0) || 
            address(IPCV(pcvAddress).collateralERC20()) == _collateralAddress),
            "The same collateral address must be used for the entire set of contracts"
        );

        emit TroveManagerAddressChanged(_troveManagerAddress);
        emit ActivePoolAddressChanged(_activePoolAddress);
        emit DefaultPoolAddressChanged(_defaultPoolAddress);
        emit StabilityPoolAddressChanged(_stabilityPoolAddress);
        emit GasPoolAddressChanged(_gasPoolAddress);
        emit CollSurplusPoolAddressChanged(_collSurplusPoolAddress);
        emit PriceFeedAddressChanged(_priceFeedAddress);
        emit SortedTrovesAddressChanged(_sortedTrovesAddress);
        emit THUSDTokenAddressChanged(_thusdTokenAddress);
        emit PCVAddressChanged(_pcvAddress);
        emit CollateralAddressChanged(_collateralAddress);

        _renounceOwnership();
    }

    /// Calls on PCV behalf
    function mintBootstrapLoanFromPCV(uint256 _thusdToMint) external {
        require(msg.sender == pcvAddress, "BorrowerOperations: caller must be PCV");
        thusdToken.mint(pcvAddress, _thusdToMint);
    }

    function burnDebtFromPCV(uint256 _thusdToBurn) external {
        require(msg.sender == pcvAddress, "BorrowerOperations: caller must be PCV");
        thusdToken.burn(pcvAddress, _thusdToBurn);
    }

    // --- Borrower Trove Operations ---

    function openTrove(uint256 _maxFeePercentage, uint256 _THUSDAmount, uint256 _assetAmount, address _upperHint, address _lowerHint) external payable override {
        ContractsCache memory contractsCache = ContractsCache(troveManager, activePool, thusdToken);
        LocalVariables_openTrove memory vars;

        vars.price = priceFeed.fetchPrice();
        bool isRecoveryMode = _checkRecoveryMode(vars.price);

        _requireValidMaxFeePercentage(_maxFeePercentage, isRecoveryMode);
        _requireTroveisNotActive(contractsCache.troveManager, msg.sender);

        vars.THUSDFee;
        vars.netDebt = _THUSDAmount;

        if (!isRecoveryMode) {
            vars.THUSDFee = _triggerBorrowingFee(contractsCache.troveManager, contractsCache.thusdToken, _THUSDAmount, _maxFeePercentage);
            vars.netDebt += vars.THUSDFee;
        }

        _requireAtLeastMinNetDebt(vars.netDebt);

        // ICR is based on the composite debt, i.e. the requested THUSD amount + THUSD borrowing fee + THUSD gas comp.
        vars.compositeDebt = _getCompositeDebt(vars.netDebt);
        assert(vars.compositeDebt > 0);

        // if ETH overwrite the asset value
        _assetAmount = getAssetAmount(_assetAmount);
        vars.ICR = LiquityMath._computeCR(_assetAmount, vars.compositeDebt, vars.price);
        vars.NICR = LiquityMath._computeNominalCR(_assetAmount, vars.compositeDebt);

        if (isRecoveryMode) {
            _requireICRisAboveCCR(vars.ICR);
        } else {
            _requireICRisAboveMCR(vars.ICR);
            uint256 newTCR = _getNewTCRFromTroveChange(_assetAmount, true, vars.compositeDebt, true, vars.price);  // bools: coll increase, debt increase
            _requireNewTCRisAboveCCR(newTCR);
        }

        // Set the trove struct's properties
        contractsCache.troveManager.setTroveStatus(msg.sender, ITroveManager.Status.active);
        contractsCache.troveManager.increaseTroveColl(msg.sender, _assetAmount);
        contractsCache.troveManager.increaseTroveDebt(msg.sender, vars.compositeDebt);

        contractsCache.troveManager.updateTroveRewardSnapshots(msg.sender);
        vars.stake = contractsCache.troveManager.updateStakeAndTotalStakes(msg.sender);

        sortedTroves.insert(msg.sender, vars.NICR, _upperHint, _lowerHint);
        vars.arrayIndex = contractsCache.troveManager.addTroveOwnerToArray(msg.sender);
        emit TroveCreated(msg.sender, vars.arrayIndex);

        /*
         * Move the collateral to the Active Pool, and mint the THUSDAmount to the borrower
         * If the user has insuffient tokens to do the transfer to the Active Pool an error will cause the transaction to revert.
         */
        _activePoolAddColl(contractsCache.activePool, _assetAmount);
        _withdrawTHUSD(contractsCache.activePool, contractsCache.thusdToken, msg.sender, _THUSDAmount, vars.netDebt);
        // Move the THUSD gas compensation to the Gas Pool
        _withdrawTHUSD(contractsCache.activePool, contractsCache.thusdToken, gasPoolAddress, THUSD_GAS_COMPENSATION, THUSD_GAS_COMPENSATION);

        emit TroveUpdated(msg.sender, vars.compositeDebt, _assetAmount, vars.stake, BorrowerOperation.openTrove);
        emit THUSDBorrowingFeePaid(msg.sender, vars.THUSDFee);
    }

    // Send collateral to a trove
    function addColl(uint256 _assetAmount, address _upperHint, address _lowerHint) external payable override {
        _assetAmount = getAssetAmount(_assetAmount);
        _adjustTrove(msg.sender, 0, 0, false, _assetAmount, _upperHint, _lowerHint, 0);
    }

    // Send collateral to a trove. Called by only the Stability Pool.
    function moveCollateralGainToTrove(address _borrower, uint256 _assetAmount, address _upperHint, address _lowerHint) external payable override {
        _requireCallerIsStabilityPool();
        _assetAmount = getAssetAmount(_assetAmount);
        _adjustTrove(_borrower, 0, 0, false, _assetAmount, _upperHint, _lowerHint, 0);
    }

    function getAssetAmount(uint256 _assetAmount) internal view returns (uint256) {
        if (collateralAddress == address(0)) {
            return msg.value;
        }

        require(msg.value == 0, "BorrowerOperations: ERC20 collateral needed, not ETH");
        return _assetAmount;
    }

    // Withdraw collateral from a trove
    function withdrawColl(uint256 _collWithdrawal, address _upperHint, address _lowerHint) external override {
        _adjustTrove(msg.sender, _collWithdrawal, 0, false, 0, _upperHint, _lowerHint, 0);
    }

    // Withdraw THUSD tokens from a trove: mint new THUSD tokens to the owner, and increase the trove's debt accordingly
    function withdrawTHUSD(uint256 _maxFeePercentage, uint256 _THUSDAmount, address _upperHint, address _lowerHint) external override {
        _adjustTrove(msg.sender, 0, _THUSDAmount, true, 0, _upperHint, _lowerHint, _maxFeePercentage);
    }

    // Repay THUSD tokens to a Trove: Burn the repaid THUSD tokens, and reduce the trove's debt accordingly
    function repayTHUSD(uint256 _THUSDAmount, address _upperHint, address _lowerHint) external override {
        _adjustTrove(msg.sender, 0, _THUSDAmount, false, 0, _upperHint, _lowerHint, 0);
    }

    function adjustTrove(uint256 _maxFeePercentage, uint256 _collWithdrawal, uint256 _THUSDChange, bool _isDebtIncrease, uint256 _assetAmount, address _upperHint, address _lowerHint) external payable override {
        _assetAmount = getAssetAmount(_assetAmount);
        _adjustTrove(msg.sender, _collWithdrawal, _THUSDChange, _isDebtIncrease, _assetAmount, _upperHint, _lowerHint, _maxFeePercentage);
    }

    /*
    * _adjustTrove(): Alongside a debt change, this function can perform either a collateral top-up or a collateral withdrawal.
    *
    * It therefore expects either a positive msg.value, or a positive _collWithdrawal argument.
    *
    * If both are positive, it will revert.
    */
    function _adjustTrove(address _borrower, uint256 _collWithdrawal, uint256 _THUSDChange, bool _isDebtIncrease, uint256 _assetAmount, address _upperHint, address _lowerHint, uint256 _maxFeePercentage) internal {
        ContractsCache memory contractsCache = ContractsCache(troveManager, activePool, thusdToken);
        LocalVariables_adjustTrove memory vars;

        vars.price = priceFeed.fetchPrice();
        bool isRecoveryMode = _checkRecoveryMode(vars.price);

        if (_isDebtIncrease) {
            _requireValidMaxFeePercentage(_maxFeePercentage, isRecoveryMode);
            _requireNonZeroDebtChange(_THUSDChange);
        }
        _requireSingularCollChange(_collWithdrawal, _assetAmount);
        _requireNonZeroAdjustment(_collWithdrawal, _THUSDChange, _assetAmount);
        _requireTroveisActive(contractsCache.troveManager, _borrower);

        // Confirm the operation is either a borrower adjusting their own trove, or a pure collateral transfer from the Stability Pool to a trove
        assert(msg.sender == _borrower || (msg.sender == stabilityPoolAddress && _assetAmount > 0 && _THUSDChange == 0));

        contractsCache.troveManager.applyPendingRewards(_borrower);

        // Get the collChange based on whether or not collateral was sent in the transaction
        (vars.collChange, vars.isCollIncrease) = _getCollChange(_assetAmount, _collWithdrawal);

        vars.netDebtChange = _THUSDChange;

        // If the adjustment incorporates a debt increase and system is in Normal Mode, then trigger a borrowing fee
        if (_isDebtIncrease && !isRecoveryMode) {
            vars.THUSDFee = _triggerBorrowingFee(contractsCache.troveManager, contractsCache.thusdToken, _THUSDChange, _maxFeePercentage);
            vars.netDebtChange += vars.THUSDFee; // The raw debt change includes the fee
        }

        vars.debt = contractsCache.troveManager.getTroveDebt(_borrower);
        vars.coll = contractsCache.troveManager.getTroveColl(_borrower);

        // Get the trove's old ICR before the adjustment, and what its new ICR will be after the adjustment
        vars.oldICR = LiquityMath._computeCR(vars.coll, vars.debt, vars.price);
        vars.newICR = _getNewICRFromTroveChange(vars.coll, vars.debt, vars.collChange, vars.isCollIncrease, vars.netDebtChange, _isDebtIncrease, vars.price);
        assert(_collWithdrawal <= vars.coll);

        // Check the adjustment satisfies all conditions for the current system mode
        _requireValidAdjustmentInCurrentMode(isRecoveryMode, _collWithdrawal, _isDebtIncrease, vars);

        // When the adjustment is a debt repayment, check it's a valid amount and that the caller has enough THUSD
        if (!_isDebtIncrease && _THUSDChange > 0) {
            _requireAtLeastMinNetDebt(_getNetDebt(vars.debt) - vars.netDebtChange);
            _requireValidTHUSDRepayment(vars.debt, vars.netDebtChange);
            _requireSufficientTHUSDBalance(contractsCache.thusdToken, _borrower, vars.netDebtChange);
        }

        (vars.newColl, vars.newDebt) = _updateTroveFromAdjustment(contractsCache.troveManager, _borrower, vars.collChange, vars.isCollIncrease, vars.netDebtChange, _isDebtIncrease);
        vars.stake = contractsCache.troveManager.updateStakeAndTotalStakes(_borrower);

        // Re-insert trove in to the sorted list
        uint256 newNICR = _getNewNominalICRFromTroveChange(vars.coll, vars.debt, vars.collChange, vars.isCollIncrease, vars.netDebtChange, _isDebtIncrease);
        sortedTroves.reInsert(_borrower, newNICR, _upperHint, _lowerHint);

        emit TroveUpdated(_borrower, vars.newDebt, vars.newColl, vars.stake, BorrowerOperation.adjustTrove);
        emit THUSDBorrowingFeePaid(msg.sender,  vars.THUSDFee);

        // Use the unmodified _THUSDChange here, as we don't send the fee to the user
        _moveTokensAndCollateralfromAdjustment(
            contractsCache.activePool,
            contractsCache.thusdToken,
            msg.sender,
            vars.collChange,
            vars.isCollIncrease,
            _THUSDChange,
            _isDebtIncrease,
            vars.netDebtChange
        );
    }

    function closeTrove() external override {
        ITroveManager troveManagerCached = troveManager;
        IActivePool activePoolCached = activePool;
        ITHUSDToken thusdTokenCached = thusdToken;
        bool canMint = thusdTokenCached.mintList(address(this));

        _requireTroveisActive(troveManagerCached, msg.sender);
        uint256 price = priceFeed.fetchPrice();
        if (canMint) {
            _requireNotInRecoveryMode(price);
        }

        troveManagerCached.applyPendingRewards(msg.sender);

        uint256 coll = troveManagerCached.getTroveColl(msg.sender);
        uint256 debt = troveManagerCached.getTroveDebt(msg.sender);

        _requireSufficientTHUSDBalance(thusdTokenCached, msg.sender, debt - THUSD_GAS_COMPENSATION);
        if (canMint) {
            uint256 newTCR = _getNewTCRFromTroveChange(coll, false, debt, false, price);
            _requireNewTCRisAboveCCR(newTCR);
        }

        troveManagerCached.removeStake(msg.sender);
        troveManagerCached.closeTrove(msg.sender);

        emit TroveUpdated(msg.sender, 0, 0, 0, BorrowerOperation.closeTrove);

        // Burn the repaid THUSD from the user's balance and the gas compensation from the Gas Pool
        _repayTHUSD(activePoolCached, thusdTokenCached, msg.sender, debt - THUSD_GAS_COMPENSATION);
        _repayTHUSD(activePoolCached, thusdTokenCached, gasPoolAddress, THUSD_GAS_COMPENSATION);

        // Send the collateral back to the user
        activePoolCached.sendCollateral(msg.sender, coll);
    }

    /**
     * Claim remaining collateral from a redemption or from a liquidation with ICR > MCR in Recovery Mode
     */
    function claimCollateral() external override {
        // send collateral from CollSurplus Pool to owner
        collSurplusPool.claimColl(msg.sender);
    }

    // --- Helper functions ---

    function _triggerBorrowingFee(ITroveManager _troveManager, ITHUSDToken _thusdToken, uint256 _THUSDAmount, uint256 _maxFeePercentage) internal returns (uint) {
        _troveManager.decayBaseRateFromBorrowing(); // decay the baseRate state variable
        uint256 THUSDFee = _troveManager.getBorrowingFee(_THUSDAmount);

        _requireUserAcceptsFee(THUSDFee, _THUSDAmount, _maxFeePercentage);

        // Send fee to PCV contract
        _thusdToken.mint(pcvAddress, THUSDFee);
        return THUSDFee;
    }

    function _getUSDValue(uint256 _coll, uint256 _price) internal pure returns (uint) {
        uint256 usdValue = _price * _coll / DECIMAL_PRECISION;

        return usdValue;
    }

    function _getCollChange(
        uint256 _collReceived,
        uint256 _requestedCollWithdrawal
    )
        internal
        pure
        returns(uint256 collChange, bool isCollIncrease)
    {
        if (_collReceived != 0) {
            collChange = _collReceived;
            isCollIncrease = true;
        } else {
            collChange = _requestedCollWithdrawal;
        }
    }

    // Update trove's coll and debt based on whether they increase or decrease
    function _updateTroveFromAdjustment
    (
        ITroveManager _troveManager,
        address _borrower,
        uint256 _collChange,
        bool _isCollIncrease,
        uint256 _debtChange,
        bool _isDebtIncrease
    )
        internal
        returns (uint, uint)
    {
        uint256 newColl = (_isCollIncrease) ? _troveManager.increaseTroveColl(_borrower, _collChange)
                                        : _troveManager.decreaseTroveColl(_borrower, _collChange);
        uint256 newDebt = (_isDebtIncrease) ? _troveManager.increaseTroveDebt(_borrower, _debtChange)
                                        : _troveManager.decreaseTroveDebt(_borrower, _debtChange);

        return (newColl, newDebt);
    }

    function _moveTokensAndCollateralfromAdjustment
    (
        IActivePool _activePool,
        ITHUSDToken _thusdToken,
        address _borrower,
        uint256 _collChange,
        bool _isCollIncrease,
        uint256 _THUSDChange,
        bool _isDebtIncrease,
        uint256 _netDebtChange
    )
        internal
    {
        if (_isDebtIncrease) {
            _withdrawTHUSD(_activePool, _thusdToken, _borrower, _THUSDChange, _netDebtChange);
        } else {
            _repayTHUSD(_activePool, _thusdToken, _borrower, _THUSDChange);
        }

        if (_isCollIncrease) {
            _activePoolAddColl(_activePool, _collChange);
        } else {
            _activePool.sendCollateral(_borrower, _collChange);
        }
    }

    // Send collateral to Active Pool and increase its recorded collateral balance
    function _activePoolAddColl(IActivePool _activePool, uint256 _amount) internal {
        sendCollateralFrom(IERC20(collateralAddress), msg.sender, address(_activePool), _amount);

        if (collateralAddress == address(0)) {
            return;
        }
        _activePool.updateCollateralBalance(_amount);
    }

    // Issue the specified amount of THUSD to _account and increases the total active debt (_netDebtIncrease potentially includes a THUSDFee)
    function _withdrawTHUSD(IActivePool _activePool, ITHUSDToken _thusdToken, address _account, uint256 _THUSDAmount, uint256 _netDebtIncrease) internal {
        _activePool.increaseTHUSDDebt(_netDebtIncrease);
        _thusdToken.mint(_account, _THUSDAmount);
    }

    // Burn the specified amount of THUSD from _account and decreases the total active debt
    function _repayTHUSD(IActivePool _activePool, ITHUSDToken _thusdToken, address _account, uint256 _THUSD) internal {
        _activePool.decreaseTHUSDDebt(_THUSD);
        _thusdToken.burn(_account, _THUSD);
    }

    // --- 'Require' wrapper functions ---

    function _requireSingularCollChange(uint256 _collWithdrawal, uint256 _assetAmount) internal pure {
        require(_assetAmount == 0 || _collWithdrawal == 0, "BorrowerOperations: Cannot withdraw and add coll");
    }

    function _requireCallerIsBorrower(address _borrower) internal view {
        require(msg.sender == _borrower, "BorrowerOps: Caller must be the borrower for a withdrawal");
    }

    function _requireNonZeroAdjustment(uint256 _collWithdrawal, uint256 _THUSDChange, uint256 _assetAmount) internal pure {
        require(_assetAmount != 0 || _collWithdrawal != 0 || _THUSDChange != 0, "BorrowerOps: There must be either a collateral change or a debt change");
    }

    function _requireTroveisActive(ITroveManager _troveManager, address _borrower) internal view {
        ITroveManager.Status status = _troveManager.getTroveStatus(_borrower);
        require(status == ITroveManager.Status.active, "BorrowerOps: Trove does not exist or is closed");
    }

    function _requireTroveisNotActive(ITroveManager _troveManager, address _borrower) internal view {
        ITroveManager.Status status = _troveManager.getTroveStatus(_borrower);
        require(status != ITroveManager.Status.active, "BorrowerOps: Trove is active");
    }

    function _requireNonZeroDebtChange(uint256 _THUSDChange) internal pure {
        require(_THUSDChange > 0, "BorrowerOps: Debt increase requires non-zero debtChange");
    }

    function _requireNotInRecoveryMode(uint256 _price) internal view {
        require(!_checkRecoveryMode(_price), "BorrowerOps: Operation not permitted during Recovery Mode");
    }

    function _requireNoCollWithdrawal(uint256 _collWithdrawal) internal pure {
        require(_collWithdrawal == 0, "BorrowerOps: Collateral withdrawal not permitted Recovery Mode");
    }

    function _requireValidAdjustmentInCurrentMode
    (
        bool _isRecoveryMode,
        uint256 _collWithdrawal,
        bool _isDebtIncrease,
        LocalVariables_adjustTrove memory _vars
    )
        internal
        view
    {
        /*
         *In Recovery Mode, only allow:
         *
         * - Pure collateral top-up
         * - Pure debt repayment
         * - Collateral top-up with debt repayment
         * - A debt increase combined with a collateral top-up which makes the ICR >= 150% and improves the ICR (and by extension improves the TCR).
         *
         * In Normal Mode, ensure:
         *
         * - The new ICR is above MCR
         * - The adjustment won't pull the TCR below CCR
         */
        if (_isRecoveryMode) {
            _requireNoCollWithdrawal(_collWithdrawal);
            if (_isDebtIncrease) {
                _requireICRisAboveCCR(_vars.newICR);
                _requireNewICRisAboveOldICR(_vars.newICR, _vars.oldICR);
            }
        } else { // if Normal Mode
            _requireICRisAboveMCR(_vars.newICR);
            _vars.newTCR = _getNewTCRFromTroveChange(_vars.collChange, _vars.isCollIncrease, _vars.netDebtChange, _isDebtIncrease, _vars.price);
            _requireNewTCRisAboveCCR(_vars.newTCR);
        }
    }

    function _requireICRisAboveMCR(uint256 _newICR) internal pure {
        require(_newICR >= MCR, "BorrowerOps: An operation that would result in ICR < MCR is not permitted");
    }

    function _requireICRisAboveCCR(uint256 _newICR) internal pure {
        require(_newICR >= CCR, "BorrowerOps: Operation must leave trove with ICR >= CCR");
    }

    function _requireNewICRisAboveOldICR(uint256 _newICR, uint256 _oldICR) internal pure {
        require(_newICR >= _oldICR, "BorrowerOps: Cannot decrease your Trove's ICR in Recovery Mode");
    }

    function _requireNewTCRisAboveCCR(uint256 _newTCR) internal pure {
        require(_newTCR >= CCR, "BorrowerOps: An operation that would result in TCR < CCR is not permitted");
    }

    function _requireAtLeastMinNetDebt(uint256 _netDebt) internal pure {
        require (_netDebt >= MIN_NET_DEBT, "BorrowerOps: Trove's net debt must be greater than minimum");
    }

    function _requireValidTHUSDRepayment(uint256 _currentDebt, uint256 _debtRepayment) internal pure {
        require(_debtRepayment <= _currentDebt - THUSD_GAS_COMPENSATION, "BorrowerOps: Amount repaid must not be larger than the Trove's debt");
    }

    function _requireCallerIsStabilityPool() internal view {
        require(msg.sender == stabilityPoolAddress, "BorrowerOps: Caller is not Stability Pool");
    }

     function _requireSufficientTHUSDBalance(ITHUSDToken _thusdToken, address _borrower, uint256 _debtRepayment) internal view {
        require(_thusdToken.balanceOf(_borrower) >= _debtRepayment, "BorrowerOps: Caller doesnt have enough THUSD to make repayment");
    }

    function _requireValidMaxFeePercentage(uint256 _maxFeePercentage, bool _isRecoveryMode) internal pure {
        if (_isRecoveryMode) {
            require(_maxFeePercentage <= DECIMAL_PRECISION,
                "Max fee percentage must less than or equal to 100%");
        } else {
            require(_maxFeePercentage >= BORROWING_FEE_FLOOR && _maxFeePercentage <= DECIMAL_PRECISION,
                "Max fee percentage must be between 0.5% and 100%");
        }
    }

    // --- ICR and TCR getters ---

    // Compute the new collateral ratio, considering the change in coll and debt. Assumes 0 pending rewards.
    function _getNewNominalICRFromTroveChange
    (
        uint256 _coll,
        uint256 _debt,
        uint256 _collChange,
        bool _isCollIncrease,
        uint256 _debtChange,
        bool _isDebtIncrease
    )
        pure
        internal
        returns (uint)
    {
        (uint256 newColl, uint256 newDebt) = _getNewTroveAmounts(_coll, _debt, _collChange, _isCollIncrease, _debtChange, _isDebtIncrease);

        uint256 newNICR = LiquityMath._computeNominalCR(newColl, newDebt);
        return newNICR;
    }

    // Compute the new collateral ratio, considering the change in coll and debt. Assumes 0 pending rewards.
    function _getNewICRFromTroveChange
    (
        uint256 _coll,
        uint256 _debt,
        uint256 _collChange,
        bool _isCollIncrease,
        uint256 _debtChange,
        bool _isDebtIncrease,
        uint256 _price
    )
        pure
        internal
        returns (uint)
    {
        (uint256 newColl, uint256 newDebt) = _getNewTroveAmounts(_coll, _debt, _collChange, _isCollIncrease, _debtChange, _isDebtIncrease);

        uint256 newICR = LiquityMath._computeCR(newColl, newDebt, _price);
        return newICR;
    }

    function _getNewTroveAmounts(
        uint256 _coll,
        uint256 _debt,
        uint256 _collChange,
        bool _isCollIncrease,
        uint256 _debtChange,
        bool _isDebtIncrease
    )
        internal
        pure
        returns (uint, uint)
    {
        uint256 newColl = _coll;
        uint256 newDebt = _debt;

        newColl = _isCollIncrease ? _coll + _collChange :  _coll - _collChange;
        newDebt = _isDebtIncrease ? _debt + _debtChange : _debt - _debtChange;

        return (newColl, newDebt);
    }

    function _getNewTCRFromTroveChange
    (
        uint256 _collChange,
        bool _isCollIncrease,
        uint256 _debtChange,
        bool _isDebtIncrease,
        uint256 _price
    )
        internal
        view
        returns (uint)
    {
        uint256 totalColl = getEntireSystemColl();
        uint256 totalDebt = getEntireSystemDebt();

        totalColl = _isCollIncrease ? totalColl + _collChange : totalColl - _collChange;
        totalDebt = _isDebtIncrease ? totalDebt + _debtChange : totalDebt - _debtChange;

        uint256 newTCR = LiquityMath._computeCR(totalColl, totalDebt, _price);
        return newTCR;
    }

    function getCompositeDebt(uint256 _debt) external pure override returns (uint) {
        return _getCompositeDebt(_debt);
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

/**
 * Based on OpenZeppelin's Ownable contract:
 * https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/access/Ownable.sol
 *
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () {
        _owner = msg.sender;
        emit OwnershipTransferred(address(0), msg.sender);
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return msg.sender == _owner;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     *
     * NOTE: This function is not safe, as it doesn’t check owner is calling it.
     * Make sure you check it before calling it.
     */
    function _renounceOwnership() internal {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

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

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;


contract BaseMath {
    uint256 constant public DECIMAL_PRECISION = 1e18;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

/**
 * @dev Interface of the ERC2612 standard as defined in the EIP.
 *
 * Adds the {permit} method, which can be used to change one's
 * {IERC20-allowance} without having to send a transaction, by signing a
 * message. This allows users to spend tokens without having to hold Ether.
 *
 * See https://eips.ethereum.org/EIPS/eip-2612.
 * 
 * Code adapted from https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2237/
 */
interface IERC2612 {
    /**
     * @dev Sets `amount` as the allowance of `spender` over `owner`'s tokens,
     * given `owner`'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(address owner, address spender, uint256 amount, 
                    uint256 deadline, uint8 v, bytes32 r, bytes32 s) external;
    
    /**
     * @dev Returns the current ERC2612 nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases `owner`'s nonce by one. This
     * prevents a signature from being used multiple times.
     *
     * `owner` can limit the time a Permit is valid for by setting `deadline` to 
     * a value in the near future. The deadline argument can be set to uint(-1) to 
     * create Permits that effectively never expire.
     */
    function nonces(address owner) external view returns (uint256);
    
    function version() external view returns (string memory);
    function permitTypeHash() external view returns (bytes32);
    function domainSeparator() external view returns (bytes32);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

interface IPriceFeed {

    // --- Events ---
    event LastGoodPriceUpdated(uint256 _lastGoodPrice);
   
    // --- Function ---
    function fetchPrice() external returns (uint);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

import "./IPool.sol";


interface IActivePool is IPool {
    // --- Events ---
    event BorrowerOperationsAddressChanged(address _newBorrowerOperationsAddress);
    event TroveManagerAddressChanged(address _newTroveManagerAddress);
    event ActivePoolTHUSDDebtUpdated(uint256 _THUSDDebt);
    event ActivePoolCollateralBalanceUpdated(uint256 _collateral);
    event CollateralAddressChanged(address _newCollateralAddress);
    event CollSurplusPoolAddressChanged(address _newCollSurplusPoolAddress);

    // --- Functions ---
    function sendCollateral(address _account, uint256 _amount) external;
    function updateCollateralBalance(uint256 _amount) external;
    function collateralAddress() external view returns(address);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
import "../Dependencies/IERC2612.sol";

interface ITHUSDToken is IERC20Metadata, IERC2612 {

    // --- Events ---

    event TroveManagerAddressAdded(address _troveManagerAddress);
    event StabilityPoolAddressAdded(address _newStabilityPoolAddress);
    event BorrowerOperationsAddressAdded(address _newBorrowerOperationsAddress);

    event THUSDTokenBalanceUpdated(address _user, uint256 _amount);

    // --- Functions ---
    function mintList(address contractAddress) external view returns (bool);
    function burnList(address contractAddress) external view returns (bool);

    function mint(address _account, uint256 _amount) external;

    function burn(address _account, uint256 _amount) external;

    function increaseAllowance(address spender, uint256 addedValue) external returns (bool);

    function decreaseAllowance(address spender, uint256 subtractedValue) external returns (bool);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

import "./IPool.sol";


interface IDefaultPool is IPool {
    // --- Events ---
    event TroveManagerAddressChanged(address _newTroveManagerAddress);
    event DefaultPoolTHUSDDebtUpdated(uint256 _THUSDDebt);
    event DefaultPoolCollateralBalanceUpdated(uint256 _collateral);
    event CollateralAddressChanged(address _newCollateralAddress);

    // --- Functions ---
    function sendCollateralToActivePool(uint256 _amount) external;
    function updateCollateralBalance(uint256 _amount) external;
    function collateralAddress() external view returns(address);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

import "./IPriceFeed.sol";


interface ILiquityBase {
    function priceFeed() external view returns (IPriceFeed);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

import "./BaseMath.sol";
import "./LiquityMath.sol";
import "../Interfaces/IActivePool.sol";
import "../Interfaces/IDefaultPool.sol";
import "../Interfaces/IPriceFeed.sol";
import "../Interfaces/ILiquityBase.sol";

/*
* Base contract for TroveManager, BorrowerOperations and StabilityPool. Contains global system constants and
* common functions.
*/
contract LiquityBase is BaseMath, ILiquityBase {

    uint256 constant public _100pct = 1e18; // 1e18 == 100%

    // Minimum collateral ratio for individual troves
    uint256 constant public MCR = 1.1e18; // 110%

    // Critical system collateral ratio. If the system's total collateral ratio (TCR) falls below the CCR, Recovery Mode is triggered.
    uint256 constant public CCR = 1.5e18; // 150%

    // Amount of THUSD to be locked in gas pool on opening troves
    uint256 constant public THUSD_GAS_COMPENSATION = 200e18;

    // Minimum amount of net THUSD debt a trove must have
    uint256 constant public MIN_NET_DEBT = 1800e18;
    // uint256 constant public MIN_NET_DEBT = 0;

    uint256 constant public PERCENT_DIVISOR = 200; // dividing by 200 yields 0.5%

    uint256 constant public BORROWING_FEE_FLOOR = DECIMAL_PRECISION / 1000 * 5; // 0.5%

    IActivePool public activePool;

    IDefaultPool public defaultPool;

    IPriceFeed public override priceFeed;

    // --- Gas compensation functions ---

    // Returns the composite debt (drawn debt + gas compensation) of a trove, for the purpose of ICR calculation
    function _getCompositeDebt(uint256 _debt) internal pure returns (uint) {
        return _debt + THUSD_GAS_COMPENSATION;
    }

    function _getNetDebt(uint256 _debt) internal pure returns (uint) {
        return _debt - THUSD_GAS_COMPENSATION;
    }

    // Return the amount of collateral to be drawn from a trove's collateral and sent as gas compensation.
    function _getCollGasCompensation(uint256 _entireColl) internal pure returns (uint) {
        return _entireColl / PERCENT_DIVISOR;
    }

    function getEntireSystemColl() public view returns (uint256 entireSystemColl) {
        uint256 activeColl = activePool.getCollateralBalance();
        uint256 liquidatedColl = defaultPool.getCollateralBalance();

        return activeColl + liquidatedColl;
    }

    function getEntireSystemDebt() public view returns (uint256 entireSystemDebt) {
        uint256 activeDebt = activePool.getTHUSDDebt();
        uint256 closedDebt = defaultPool.getTHUSDDebt();

        return activeDebt + closedDebt;
    }

    function _getTCR(uint256 _price) internal view returns (uint256 TCR) {
        uint256 entireSystemColl = getEntireSystemColl();
        uint256 entireSystemDebt = getEntireSystemDebt();

        TCR = LiquityMath._computeCR(entireSystemColl, entireSystemDebt, _price);
        return TCR;
    }

    function _checkRecoveryMode(uint256 _price) internal view returns (bool) {
        uint256 TCR = _getTCR(_price);
        return TCR < CCR;
    }

    function _requireUserAcceptsFee(uint256 _fee, uint256 _amount, uint256 _maxFeePercentage) internal pure {
        uint256 feePercentage = _fee * DECIMAL_PRECISION / _amount;
        require(feePercentage <= _maxFeePercentage, "Fee exceeded provided maximum");
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

library LiquityMath {

    uint256 internal constant DECIMAL_PRECISION = 1e18;

    /* Precision for Nominal ICR (independent of price). Rationale for the value:
     *
     * - Making it “too high” could lead to overflows.
     * - Making it “too low” could lead to an ICR equal to zero, due to truncation from Solidity floor division.
     *
     * This value of 1e20 is chosen for safety: the NICR will only overflow for numerator > ~1e39 ETH,
     * and will only truncate to 0 if the denominator is at least 1e20 times greater than the numerator.
     *
     */
    uint256 internal constant NICR_PRECISION = 1e20;

    function _min(uint256 _a, uint256 _b) internal pure returns (uint) {
        return (_a < _b) ? _a : _b;
    }

    function _max(uint256 _a, uint256 _b) internal pure returns (uint) {
        return (_a >= _b) ? _a : _b;
    }

    /*
    * Multiply two decimal numbers and use normal rounding rules:
    * -round product up if 19'th mantissa digit >= 5
    * -round product down if 19'th mantissa digit < 5
    *
    * Used only inside the exponentiation, _decPow().
    */
    function decMul(uint256 x, uint256 y) internal pure returns (uint256 decProd) {
        uint256 prod_xy = x * y;

        decProd = (prod_xy + (DECIMAL_PRECISION / 2)) / DECIMAL_PRECISION;
    }

    /*
    * _decPow: Exponentiation function for 18-digit decimal base, and integer exponent n.
    *
    * Uses the efficient "exponentiation by squaring" algorithm. O(log(n)) complexity.
    *
    * Called by one function that represent time in units of minutes:
    * 1) TroveManager._calcDecayedBaseRate
    *
    * The exponent is capped to avoid reverting due to overflow. The cap 525600000 equals
    * "minutes in 1000 years": 60 * 24 * 365 * 1000
    *
    * If a period of > 1000 years is ever used as an exponent in either of the above functions, the result will be
    * negligibly different from just passing the cap, since:
    *
    * In function 1), the decayed base rate will be 0 for 1000 years or > 1000 years
    * In function 2), the difference in tokens issued at 1000 years and any time > 1000 years, will be negligible
    */
    function _decPow(uint256 _base, uint256 _minutes) internal pure returns (uint) {

        if (_minutes > 525600000) {_minutes = 525600000;}  // cap to avoid overflow

        if (_minutes == 0) {return DECIMAL_PRECISION;}

        uint256 y = DECIMAL_PRECISION;
        uint256 x = _base;
        uint256 n = _minutes;

        // Exponentiation-by-squaring
        while (n > 1) {
            if (n % 2 == 0) {
                x = decMul(x, x);
                n = n / 2;
            } else { // if (n % 2 != 0)
                y = decMul(x, y);
                x = decMul(x, x);
                n = (n - 1) / 2;
            }
        }

        return decMul(x, y);
  }

    function _getAbsoluteDifference(uint256 _a, uint256 _b) internal pure returns (uint) {
        return (_a >= _b) ? _a - _b : _b - _a;
    }

    function _computeNominalCR(uint256 _coll, uint256 _debt) internal pure returns (uint) {
        if (_debt > 0) {
            return _coll * NICR_PRECISION / _debt;
        }
        // Return the maximal value for uint256 if the Trove has a debt of 0. Represents "infinite" CR.
        else { // if (_debt == 0)
            return type(uint256).max;
        }
    }

    function _computeCR(uint256 _coll, uint256 _debt, uint256 _price) internal pure returns (uint) {
        if (_debt > 0) {
            uint256 newCollRatio = _coll * _price / _debt;

            return newCollRatio;
        }
        // Return the maximal value for uint256 if the Trove has a debt of 0. Represents "infinite" CR.
        else { // if (_debt == 0)
            return type(uint256).max;
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

// Common interface for the SortedTroves Doubly Linked List.
interface ISortedTroves {

    // --- Events ---
    
    event SortedTrovesAddressChanged(address _sortedDoublyLLAddress);
    event BorrowerOperationsAddressChanged(address _borrowerOperationsAddress);
    event NodeAdded(address _id, uint256 _NICR);
    event NodeRemoved(address _id);

    // --- Functions ---
    
    function setParams(uint256 _size, address _TroveManagerAddress, address _borrowerOperationsAddress) external;

    function insert(address _id, uint256 _ICR, address _prevId, address _nextId) external;

    function remove(address _id) external;

    function reInsert(address _id, uint256 _newICR, address _prevId, address _nextId) external;

    function contains(address _id) external view returns (bool);

    function isFull() external view returns (bool);

    function isEmpty() external view returns (bool);

    function getSize() external view returns (uint256);

    function getMaxSize() external view returns (uint256);

    function getFirst() external view returns (address);

    function getLast() external view returns (address);

    function getNext(address _id) external view returns (address);

    function getPrev(address _id) external view returns (address);

    function validInsertPosition(uint256 _ICR, address _prevId, address _nextId) external view returns (bool);

    function findInsertPosition(uint256 _ICR, address _prevId, address _nextId) external view returns (address, address);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

import "./ILiquityBase.sol";
import "./IStabilityPool.sol";
import "./ITHUSDToken.sol";
import "./IPCV.sol";


// Common interface for the Trove Manager.
interface ITroveManager is ILiquityBase {

    enum Status {
        nonExistent,
        active,
        closedByOwner,
        closedByLiquidation,
        closedByRedemption
    }

    // --- Events ---

    event BorrowerOperationsAddressChanged(address _newBorrowerOperationsAddress);
    event PriceFeedAddressChanged(address _newPriceFeedAddress);
    event THUSDTokenAddressChanged(address _newTHUSDTokenAddress);
    event ActivePoolAddressChanged(address _activePoolAddress);
    event DefaultPoolAddressChanged(address _defaultPoolAddress);
    event StabilityPoolAddressChanged(address _stabilityPoolAddress);
    event GasPoolAddressChanged(address _gasPoolAddress);
    event CollSurplusPoolAddressChanged(address _collSurplusPoolAddress);
    event SortedTrovesAddressChanged(address _sortedTrovesAddress);
    event PCVAddressChanged(address _pcvAddress);

    event Liquidation(uint256 _liquidatedDebt, uint256 _liquidatedColl, uint256 _collGasCompensation, uint256 _THUSDGasCompensation);
    event Redemption(uint256 _attemptedTHUSDAmount, uint256 _actualTHUSDAmount, uint256 _collateralSent, uint256 _collateralFee);
    event TroveUpdated(address indexed _borrower, uint256 _debt, uint256 _coll, uint256 stake, uint8 operation);
    event TroveLiquidated(address indexed _borrower, uint256 _debt, uint256 _coll, uint8 operation);
    event BaseRateUpdated(uint256 _baseRate);
    event LastFeeOpTimeUpdated(uint256 _lastFeeOpTime);
    event TotalStakesUpdated(uint256 _newTotalStakes);
    event SystemSnapshotsUpdated(uint256 _totalStakesSnapshot, uint256 _totalCollateralSnapshot);
    event LTermsUpdated(uint256 _L_Collateral, uint256 _L_THUSDDebt);
    event TroveSnapshotsUpdated(uint256 _L_Collateral, uint256 _L_THUSDDebt);
    event TroveIndexUpdated(address _borrower, uint256 _newIndex);

    // --- Functions ---

    function setAddresses(
        address _borrowerOperationsAddress,
        address _activePoolAddress,
        address _defaultPoolAddress,
        address _stabilityPoolAddress,
        address _gasPoolAddress,
        address _collSurplusPoolAddress,
        address _priceFeedAddress,
        address _thusdTokenAddress,
        address _sortedTrovesAddress,
        address _pcvAddress
    ) external;

    function stabilityPool() external view returns (IStabilityPool);
    function thusdToken() external view returns (ITHUSDToken);
    function pcv() external view returns (IPCV);

    function getTroveOwnersCount() external view returns (uint);

    function getTroveFromTroveOwnersArray(uint256 _index) external view returns (address);

    function getNominalICR(address _borrower) external view returns (uint);
    function getCurrentICR(address _borrower, uint256 _price) external view returns (uint);

    function liquidate(address _borrower) external;

    function liquidateTroves(uint256 _n) external;

    function batchLiquidateTroves(address[] calldata _troveArray) external;

    function redeemCollateral(
        uint256 _THUSDAmount,
        address _firstRedemptionHint,
        address _upperPartialRedemptionHint,
        address _lowerPartialRedemptionHint,
        uint256 _partialRedemptionHintNICR,
        uint256 _maxIterations,
        uint256 _maxFee
    ) external;

    function updateStakeAndTotalStakes(address _borrower) external returns (uint);

    function updateTroveRewardSnapshots(address _borrower) external;

    function addTroveOwnerToArray(address _borrower) external returns (uint256 index);

    function applyPendingRewards(address _borrower) external;

    function getPendingCollateralReward(address _borrower) external view returns (uint);

    function getPendingTHUSDDebtReward(address _borrower) external view returns (uint);

     function hasPendingRewards(address _borrower) external view returns (bool);

    function getEntireDebtAndColl(address _borrower) external view returns (
        uint256 debt,
        uint256 coll,
        uint256 pendingTHUSDDebtReward,
        uint256 pendingCollateralReward
    );

    function closeTrove(address _borrower) external;

    function removeStake(address _borrower) external;

    function getRedemptionRate() external view returns (uint);
    function getRedemptionRateWithDecay() external view returns (uint);

    function getRedemptionFeeWithDecay(uint256 _collateralDrawn) external view returns (uint);

    function getBorrowingRate() external view returns (uint);
    function getBorrowingRateWithDecay() external view returns (uint);

    function getBorrowingFee(uint256 THUSDDebt) external view returns (uint);
    function getBorrowingFeeWithDecay(uint256 _THUSDDebt) external view returns (uint);

    function decayBaseRateFromBorrowing() external;

    function getTroveStatus(address _borrower) external view returns (Status);

    function getTroveStake(address _borrower) external view returns (uint);

    function getTroveDebt(address _borrower) external view returns (uint);

    function getTroveColl(address _borrower) external view returns (uint);

    function setTroveStatus(address _borrower, Status _status) external;

    function increaseTroveColl(address _borrower, uint256 _collIncrease) external returns (uint);

    function decreaseTroveColl(address _borrower, uint256 _collDecrease) external returns (uint);

    function increaseTroveDebt(address _borrower, uint256 _debtIncrease) external returns (uint);

    function decreaseTroveDebt(address _borrower, uint256 _collDecrease) external returns (uint);

    function getTCR(uint256 _price) external view returns (uint);

    function checkRecoveryMode(uint256 _price) external view returns (bool);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

/*
 * The Stability Pool holds THUSD tokens deposited by Stability Pool depositors.
 *
 * When a trove is liquidated, then depending on system conditions, some of its THUSD debt gets offset with
 * THUSD in the Stability Pool:  that is, the offset debt evaporates, and an equal amount of THUSD tokens in the Stability Pool is burned.
 *
 * Thus, a liquidation causes each depositor to receive a THUSD loss, in proportion to their deposit as a share of total deposits.
 * They also receive an collateral gain, as the collateral of the liquidated trove is distributed among Stability depositors,
 * in the same proportion.
 *
 * When a liquidation occurs, it depletes every deposit by the same fraction: for example, a liquidation that depletes 40%
 * of the total THUSD in the Stability Pool, depletes 40% of each deposit.
 *
 * A deposit that has experienced a series of liquidations is termed a "compounded deposit": each liquidation depletes the deposit,
 * multiplying it by some factor in range ]0,1[
 *
 * Please see the implementation spec in the proof document, which closely follows on from the compounded deposit / collateral gain derivations:
 * https://github.com/liquity/liquity/blob/master/papers/Scalable_Reward_Distribution_with_Compounding_Stakes.pdf
 *
 */
interface IStabilityPool {

    // --- Events ---

    event StabilityPoolCollateralBalanceUpdated(uint256 _newBalance);
    event StabilityPoolTHUSDBalanceUpdated(uint256 _newBalance);

    event BorrowerOperationsAddressChanged(address _newBorrowerOperationsAddress);
    event TroveManagerAddressChanged(address _newTroveManagerAddress);
    event ActivePoolAddressChanged(address _newActivePoolAddress);
    event DefaultPoolAddressChanged(address _newDefaultPoolAddress);
    event THUSDTokenAddressChanged(address _newTHUSDTokenAddress);
    event SortedTrovesAddressChanged(address _newSortedTrovesAddress);
    event PriceFeedAddressChanged(address _newPriceFeedAddress);
    event CollateralAddressChanged(address _newCollateralAddress);

    event P_Updated(uint256 _P);
    event S_Updated(uint256 _S, uint128 _epoch, uint128 _scale);
    event EpochUpdated(uint128 _currentEpoch);
    event ScaleUpdated(uint128 _currentScale);

    event DepositSnapshotUpdated(address indexed _depositor, uint256 _P, uint256 _S);
    event UserDepositChanged(address indexed _depositor, uint256 _newDeposit);

    event CollateralGainWithdrawn(address indexed _depositor, uint256 _collateral, uint256 _THUSDLoss);
    event CollateralSent(address _to, uint256 _amount);

    // --- Functions ---

    /*
     * Called only once on init, to set addresses of other Liquity contracts
     * Callable only by owner, renounces ownership at the end
     */
    function setAddresses(
        address _borrowerOperationsAddress,
        address _troveManagerAddress,
        address _activePoolAddress,
        address _thusdTokenAddress,
        address _sortedTrovesAddress,
        address _priceFeedAddress,
        address _collateralAddress
    ) external;

    /*
     * Initial checks:
     * - _amount is not zero
     * ---
     * - Sends depositor's accumulated gains (collateral) to depositor
     */
    function provideToSP(uint256 _amount) external;

    /*
     * Initial checks:
     * - _amount is zero or there are no under collateralized troves left in the system
     * - User has a non zero deposit
     * ---
     * - Sends all depositor's accumulated gains (collateral) to depositor
     * - Decreases deposit stake, and takes new snapshot.
     *
     * If _amount > userDeposit, the user withdraws all of their compounded deposit.
     */
    function withdrawFromSP(uint256 _amount) external;

    /*
     * Initial checks:
     * - User has a non zero deposit
     * - User has an open trove
     * - User has some collateral gain
     * ---
     * - Transfers the depositor's entire collateral gain from the Stability Pool to the caller's trove
     * - Leaves their compounded deposit in the Stability Pool
     * - Updates snapshots for deposit
     */
    function withdrawCollateralGainToTrove(address _upperHint, address _lowerHint) external;

    /*
     * Initial checks:
     * - Caller is TroveManager
     * ---
     * Cancels out the specified debt against the THUSD contained in the Stability Pool (as far as possible)
     * and transfers the Trove's collateral from ActivePool to StabilityPool.
     * Only called by liquidation functions in the TroveManager.
     */
    function offset(uint256 _debt, uint256 _coll) external;

    /*
     * Returns the total amount of collateral held by the pool, accounted in an internal variable instead of `balance`,
     * to exclude edge cases like collateral received from a self-destruct.
     */
    function getCollateralBalance() external view returns (uint);

    /*
     * Returns THUSD held in the pool. Changes when users deposit/withdraw, and when Trove debt is offset.
     */
    function getTotalTHUSDDeposits() external view returns (uint);

    /*
     * Calculates the collateral gain earned by the deposit since its last snapshots were taken.
     */
    function getDepositorCollateralGain(address _depositor) external view returns (uint);

    /*
     * Return the user's compounded deposit.
     */
    function getCompoundedTHUSDDeposit(address _depositor) external view returns (uint);

    /*
     * Only callable by Active Pool, updates ERC20 tokens recieved
     */
    function updateCollateralBalance(uint256 _amount) external;
    /*
     * Fallback function
     * Only callable by Active Pool, it just accounts for ETH received
     * receive() external payable;
     */
    
    function collateralAddress() external view returns(address);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;


contract CheckContract {
    /**
     * Check that the account is an already deployed non-destroyed contract.
     * See: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Address.sol#L12
     */
    function checkContract(address _account) internal view {
        require(_account != address(0), "Account cannot be zero address");

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(_account) }
        require(size > 0, "Account code size cannot be zero");
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (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
     *
     * Furthermore, `isContract` will also return true if the target contract within
     * the same transaction is already scheduled for destruction by `SELFDESTRUCT`,
     * which only has an effect at the end of a transaction.
     * ====
     *
     * [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://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.8.0/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

pragma solidity ^0.8.17;


import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";


contract SendCollateral {
    using SafeERC20 for IERC20;

    /**
     * Sends collateral to recipient
     */
    function sendCollateral(IERC20 _collateralERC20, address _recipient, uint256 _amount) internal {
        if (address(_collateralERC20) == address(0)) {
            // ETH
            // require(_amount <= address(this).balance, "Not enough ETH");
            (bool success, ) = _recipient.call{ value: _amount }(""); // re-entry is fine here
            require(success, "Sending ETH failed");
        } else {
            // ERC20
            // require(_amount <= _collateralERC20.balanceOf(address(this)), "Not enough collateral");
            _collateralERC20.safeTransfer(_recipient, _amount); 
        }
    }
    
    /**
     * Sends collateral to recipient
     */
    function sendCollateralFrom(IERC20 _collateralERC20, address _from, address _recipient, uint256 _amount) internal {
        if (address(_collateralERC20) == address(0)) {
            // ETH
            // require(_amount <= address(this).balance, "Not enough ETH");
            (bool success, ) = _recipient.call{ value: _amount }(""); // re-entry is fine here
            require(success, "Sending ETH failed");
        } else {
            // ERC20
            // require(_amount <= _collateralERC20.balanceOf(address(this)), "Not enough collateral");
            _collateralERC20.safeTransferFrom(_from, _recipient, _amount);
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;


interface ICollSurplusPool {

    // --- Events ---

    event BorrowerOperationsAddressChanged(address _newBorrowerOperationsAddress);
    event TroveManagerAddressChanged(address _newTroveManagerAddress);
    event ActivePoolAddressChanged(address _newActivePoolAddress);
    event CollateralAddressChanged(address _newCollateralAddress);

    event CollBalanceUpdated(address indexed _account, uint256 _newBalance);
    event CollateralSent(address _to, uint256 _amount);

    // --- Contract setters ---

    function setAddresses(
        address _borrowerOperationsAddress,
        address _troveManagerAddress,
        address _activePoolAddress,
        address _collateralAddress
    ) external;

    function getCollateralBalance() external view returns (uint);

    function getCollateral(address _account) external view returns (uint);

    function accountSurplus(address _account, uint256 _amount) external;

    function claimColl(address _account) external;

    function updateCollateralBalance(uint256 _amount) external;
    
    function collateralAddress() external view returns(address);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

// Common interface for the Trove Manager.
interface IBorrowerOperations {

    // --- Events ---

    event TroveManagerAddressChanged(address _newTroveManagerAddress);
    event ActivePoolAddressChanged(address _activePoolAddress);
    event DefaultPoolAddressChanged(address _defaultPoolAddress);
    event StabilityPoolAddressChanged(address _stabilityPoolAddress);
    event GasPoolAddressChanged(address _gasPoolAddress);
    event CollSurplusPoolAddressChanged(address _collSurplusPoolAddress);
    event PriceFeedAddressChanged(address  _newPriceFeedAddress);
    event SortedTrovesAddressChanged(address _sortedTrovesAddress);
    event THUSDTokenAddressChanged(address _thusdTokenAddress);
    event PCVAddressChanged(address _pcvAddress);
    event CollateralAddressChanged(address _newCollateralAddress);

    event TroveCreated(address indexed _borrower, uint256 arrayIndex);
    event TroveUpdated(address indexed _borrower, uint256 _debt, uint256 _coll, uint256 stake, uint8 operation);
    event THUSDBorrowingFeePaid(address indexed _borrower, uint256 _THUSDFee);

    // --- Functions ---

    function setAddresses(
        address _troveManagerAddress,
        address _activePoolAddress,
        address _defaultPoolAddress,
        address _stabilityPoolAddress,
        address _gasPoolAddress,
        address _collSurplusPoolAddress,
        address _priceFeedAddress,
        address _sortedTrovesAddress,
        address _thusdTokenAddress,
        address _pcvAddress,
        address _collateralAddress

    ) external;

    function openTrove(uint256 _maxFee, uint256 _THUSDAmount, uint256 _assetAmount, address _upperHint, address _lowerHint) external payable;

    function addColl(uint256 _assetAmount, address _upperHint, address _lowerHint) external payable;

    function moveCollateralGainToTrove(address _user, uint256 _assetAmount, address _upperHint, address _lowerHint) external payable;

    function withdrawColl(uint256 _amount, address _upperHint, address _lowerHint) external;

    function withdrawTHUSD(uint256 _maxFee, uint256 _amount, address _upperHint, address _lowerHint) external;

    function repayTHUSD(uint256 _amount, address _upperHint, address _lowerHint) external;

    function closeTrove() external;

    function adjustTrove(uint256 _maxFee, uint256 _collWithdrawal, uint256 _debtChange, bool isDebtIncrease, uint256 _assetAmount, address _upperHint, address _lowerHint) external payable;

    function claimCollateral() external;

    function getCompositeDebt(uint256 _debt) external pure returns (uint);

    function collateralAddress() external view returns(address);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/IERC20Permit.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance + value));
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance - value));
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Compatible with tokens that require the approval to be set to
     * 0 before setting it to a non-zero value.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeWithSelector(token.approve.selector, spender, value);

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, 0));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Use a ERC-2612 signature to set the `owner` approval toward `spender` on `token`.
     * Revert on invalid signature.
     */
    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        require(returndata.length == 0 || abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return
            success && (returndata.length == 0 || abi.decode(returndata, (bool))) && Address.isContract(address(token));
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/extensions/IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

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

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}