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

pragma solidity ^0.8.0;

/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

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

/**
 * @title Base for contracts that are managed by the Origin Protocol's Governor.
 * @dev Copy of the openzeppelin Ownable.sol contract with nomenclature change
 *      from owner to governor and renounce methods removed. Does not use
 *      Context.sol like Ownable.sol does for simplification.
 * @author Origin Protocol Inc
 */
contract Governable {
    // Storage position of the owner and pendingOwner of the contract
    // keccak256("OUSD.governor");
    bytes32 private constant governorPosition =
        0x7bea13895fa79d2831e0a9e28edede30099005a50d652d8957cf8a607ee6ca4a;

    // keccak256("OUSD.pending.governor");
    bytes32 private constant pendingGovernorPosition =
        0x44c4d30b2eaad5130ad70c3ba6972730566f3e6359ab83e800d905c61b1c51db;

    // keccak256("OUSD.reentry.status");
    bytes32 private constant reentryStatusPosition =
        0x53bf423e48ed90e97d02ab0ebab13b2a235a6bfbe9c321847d5c175333ac4535;

    // See OpenZeppelin ReentrancyGuard implementation
    uint256 constant _NOT_ENTERED = 1;
    uint256 constant _ENTERED = 2;

    event PendingGovernorshipTransfer(
        address indexed previousGovernor,
        address indexed newGovernor
    );

    event GovernorshipTransferred(
        address indexed previousGovernor,
        address indexed newGovernor
    );

    /**
     * @dev Initializes the contract setting the deployer as the initial Governor.
     */
    constructor() {
        _setGovernor(msg.sender);
        emit GovernorshipTransferred(address(0), _governor());
    }

    /**
     * @notice Returns the address of the current Governor.
     */
    function governor() public view returns (address) {
        return _governor();
    }

    /**
     * @dev Returns the address of the current Governor.
     */
    function _governor() internal view returns (address governorOut) {
        bytes32 position = governorPosition;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            governorOut := sload(position)
        }
    }

    /**
     * @dev Returns the address of the pending Governor.
     */
    function _pendingGovernor()
        internal
        view
        returns (address pendingGovernor)
    {
        bytes32 position = pendingGovernorPosition;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            pendingGovernor := sload(position)
        }
    }

    /**
     * @dev Throws if called by any account other than the Governor.
     */
    modifier onlyGovernor() {
        require(isGovernor(), "Caller is not the Governor");
        _;
    }

    /**
     * @notice Returns true if the caller is the current Governor.
     */
    function isGovernor() public view returns (bool) {
        return msg.sender == _governor();
    }

    function _setGovernor(address newGovernor) internal {
        bytes32 position = governorPosition;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            sstore(position, newGovernor)
        }
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        bytes32 position = reentryStatusPosition;
        uint256 _reentry_status;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            _reentry_status := sload(position)
        }

        // On the first call to nonReentrant, _notEntered will be true
        require(_reentry_status != _ENTERED, "Reentrant call");

        // Any calls to nonReentrant after this point will fail
        // solhint-disable-next-line no-inline-assembly
        assembly {
            sstore(position, _ENTERED)
        }

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        // solhint-disable-next-line no-inline-assembly
        assembly {
            sstore(position, _NOT_ENTERED)
        }
    }

    function _setPendingGovernor(address newGovernor) internal {
        bytes32 position = pendingGovernorPosition;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            sstore(position, newGovernor)
        }
    }

    /**
     * @notice Transfers Governance of the contract to a new account (`newGovernor`).
     * Can only be called by the current Governor. Must be claimed for this to complete
     * @param _newGovernor Address of the new Governor
     */
    function transferGovernance(address _newGovernor) external onlyGovernor {
        _setPendingGovernor(_newGovernor);
        emit PendingGovernorshipTransfer(_governor(), _newGovernor);
    }

    /**
     * @notice Claim Governance of the contract to a new account (`newGovernor`).
     * Can only be called by the new Governor.
     */
    function claimGovernance() external {
        require(
            msg.sender == _pendingGovernor(),
            "Only the pending Governor can complete the claim"
        );
        _changeGovernor(msg.sender);
    }

    /**
     * @dev Change Governance of the contract to a new account (`newGovernor`).
     * @param _newGovernor Address of the new Governor
     */
    function _changeGovernor(address _newGovernor) internal {
        require(_newGovernor != address(0), "New Governor is address(0)");
        emit GovernorshipTransferred(_governor(), _newGovernor);
        _setGovernor(_newGovernor);
    }
}

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

import { IBasicToken } from "../interfaces/IBasicToken.sol";

library Helpers {
    /**
     * @notice Fetch the `symbol()` from an ERC20 token
     * @dev Grabs the `symbol()` from a contract
     * @param _token Address of the ERC20 token
     * @return string Symbol of the ERC20 token
     */
    function getSymbol(address _token) internal view returns (string memory) {
        string memory symbol = IBasicToken(_token).symbol();
        return symbol;
    }

    /**
     * @notice Fetch the `decimals()` from an ERC20 token
     * @dev Grabs the `decimals()` from a contract and fails if
     *      the decimal value does not live within a certain range
     * @param _token Address of the ERC20 token
     * @return uint256 Decimals of the ERC20 token
     */
    function getDecimals(address _token) internal view returns (uint256) {
        uint256 decimals = IBasicToken(_token).decimals();
        require(
            decimals >= 4 && decimals <= 18,
            "Token must have sufficient decimal places"
        );

        return decimals;
    }
}

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

interface IBasicToken {
    function symbol() external view returns (string memory);

    function decimals() external view returns (uint8);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/IERC20.sol)

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: MIT
pragma solidity ^0.8.0;

/**
 * @title Platform interface to integrate with lending platform like Compound, AAVE etc.
 */
interface IStrategy {
    /**
     * @dev Deposit the given asset to platform
     * @param _asset asset address
     * @param _amount Amount to deposit
     */
    function deposit(address _asset, uint256 _amount) external;

    /**
     * @dev Deposit the entire balance of all supported assets in the Strategy
     *      to the platform
     */
    function depositAll() external;

    /**
     * @dev Withdraw given asset from Lending platform
     */
    function withdraw(
        address _recipient,
        address _asset,
        uint256 _amount
    ) external;

    /**
     * @dev Liquidate all assets in strategy and return them to Vault.
     */
    function withdrawAll() external;

    /**
     * @dev Returns the current balance of the given asset.
     */
    function checkBalance(address _asset)
        external
        view
        returns (uint256 balance);

    /**
     * @dev Returns bool indicating whether strategy supports asset.
     */
    function supportsAsset(address _asset) external view returns (bool);

    /**
     * @dev Collect reward tokens from the Strategy.
     */
    function collectRewardTokens() external;

    /**
     * @dev The address array of the reward tokens for the Strategy.
     */
    function getRewardTokenAddresses() external view returns (address[] memory);
}

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

import { VaultStorage } from "../vault/VaultStorage.sol";

interface IVault {
    event AssetSupported(address _asset);
    event AssetDefaultStrategyUpdated(address _asset, address _strategy);
    event AssetAllocated(address _asset, address _strategy, uint256 _amount);
    event StrategyApproved(address _addr);
    event StrategyRemoved(address _addr);
    event Mint(address _addr, uint256 _value);
    event Redeem(address _addr, uint256 _value);
    event CapitalPaused();
    event CapitalUnpaused();
    event RebasePaused();
    event RebaseUnpaused();
    event VaultBufferUpdated(uint256 _vaultBuffer);
    event RedeemFeeUpdated(uint256 _redeemFeeBps);
    event PriceProviderUpdated(address _priceProvider);
    event AllocateThresholdUpdated(uint256 _threshold);
    event RebaseThresholdUpdated(uint256 _threshold);
    event StrategistUpdated(address _address);
    event MaxSupplyDiffChanged(uint256 maxSupplyDiff);
    event YieldDistribution(address _to, uint256 _yield, uint256 _fee);
    event TrusteeFeeBpsChanged(uint256 _basis);
    event TrusteeAddressChanged(address _address);
    event SwapperChanged(address _address);
    event SwapAllowedUndervalueChanged(uint256 _basis);
    event SwapSlippageChanged(address _asset, uint256 _basis);
    event Swapped(
        address indexed _fromAsset,
        address indexed _toAsset,
        uint256 _fromAssetAmount,
        uint256 _toAssetAmount
    );

    // Governable.sol
    function transferGovernance(address _newGovernor) external;

    function claimGovernance() external;

    function governor() external view returns (address);

    // VaultAdmin.sol
    function setPriceProvider(address _priceProvider) external;

    function priceProvider() external view returns (address);

    function setRedeemFeeBps(uint256 _redeemFeeBps) external;

    function redeemFeeBps() external view returns (uint256);

    function setVaultBuffer(uint256 _vaultBuffer) external;

    function vaultBuffer() external view returns (uint256);

    function setAutoAllocateThreshold(uint256 _threshold) external;

    function autoAllocateThreshold() external view returns (uint256);

    function setRebaseThreshold(uint256 _threshold) external;

    function rebaseThreshold() external view returns (uint256);

    function setStrategistAddr(address _address) external;

    function strategistAddr() external view returns (address);

    function setMaxSupplyDiff(uint256 _maxSupplyDiff) external;

    function maxSupplyDiff() external view returns (uint256);

    function setTrusteeAddress(address _address) external;

    function trusteeAddress() external view returns (address);

    function setTrusteeFeeBps(uint256 _basis) external;

    function trusteeFeeBps() external view returns (uint256);

    function ousdMetaStrategy() external view returns (address);

    function setSwapper(address _swapperAddr) external;

    function setSwapAllowedUndervalue(uint16 _percentageBps) external;

    function setOracleSlippage(address _asset, uint16 _allowedOracleSlippageBps)
        external;

    function supportAsset(address _asset, uint8 _supportsAsset) external;

    function approveStrategy(address _addr) external;

    function removeStrategy(address _addr) external;

    function setAssetDefaultStrategy(address _asset, address _strategy)
        external;

    function assetDefaultStrategies(address _asset)
        external
        view
        returns (address);

    function pauseRebase() external;

    function unpauseRebase() external;

    function rebasePaused() external view returns (bool);

    function pauseCapital() external;

    function unpauseCapital() external;

    function capitalPaused() external view returns (bool);

    function transferToken(address _asset, uint256 _amount) external;

    function priceUnitMint(address asset) external view returns (uint256);

    function priceUnitRedeem(address asset) external view returns (uint256);

    function withdrawAllFromStrategy(address _strategyAddr) external;

    function withdrawAllFromStrategies() external;

    function withdrawFromStrategy(
        address _strategyFromAddress,
        address[] calldata _assets,
        uint256[] calldata _amounts
    ) external;

    function depositToStrategy(
        address _strategyToAddress,
        address[] calldata _assets,
        uint256[] calldata _amounts
    ) external;

    // VaultCore.sol
    function mint(
        address _asset,
        uint256 _amount,
        uint256 _minimumOusdAmount
    ) external;

    function mintForStrategy(uint256 _amount) external;

    function redeem(uint256 _amount, uint256 _minimumUnitAmount) external;

    function burnForStrategy(uint256 _amount) external;

    function redeemAll(uint256 _minimumUnitAmount) external;

    function allocate() external;

    function rebase() external;

    function swapCollateral(
        address fromAsset,
        address toAsset,
        uint256 fromAssetAmount,
        uint256 minToAssetAmount,
        bytes calldata data
    ) external returns (uint256 toAssetAmount);

    function totalValue() external view returns (uint256 value);

    function checkBalance(address _asset) external view returns (uint256);

    function calculateRedeemOutputs(uint256 _amount)
        external
        view
        returns (uint256[] memory);

    function getAssetCount() external view returns (uint256);

    function getAssetConfig(address _asset)
        external
        view
        returns (VaultStorage.Asset memory config);

    function getAllAssets() external view returns (address[] memory);

    function getStrategyCount() external view returns (uint256);

    function swapper() external view returns (address);

    function allowedSwapUndervalue() external view returns (uint256);

    function getAllStrategies() external view returns (address[] memory);

    function isSupportedAsset(address _asset) external view returns (bool);

    function netOusdMintForStrategyThreshold() external view returns (uint256);

    function setOusdMetaStrategy(address _ousdMetaStrategy) external;

    function setNetOusdMintForStrategyThreshold(uint256 _threshold) external;

    function netOusdMintedForStrategy() external view returns (int256);

    function weth() external view returns (address);

    function cacheWETHAssetIndex() external;

    function wethAssetIndex() external view returns (uint256);

    function initialize(address, address) external;

    function setAdminImpl(address) external;

    function removeAsset(address _asset) external;
}

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

interface IWETH9 {
    event Approval(address indexed src, address indexed guy, uint256 wad);
    event Deposit(address indexed dst, uint256 wad);
    event Transfer(address indexed src, address indexed dst, uint256 wad);
    event Withdrawal(address indexed src, uint256 wad);

    function allowance(address, address) external view returns (uint256);

    function approve(address guy, uint256 wad) external returns (bool);

    function balanceOf(address) external view returns (uint256);

    function decimals() external view returns (uint8);

    function deposit() external payable;

    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    function totalSupply() external view returns (uint256);

    function transfer(address dst, uint256 wad) external returns (bool);

    function transferFrom(
        address src,
        address dst,
        uint256 wad
    ) external returns (bool);

    function withdraw(uint256 wad) external;
}

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

/**
 * @title Base contract any contracts that need to initialize state after deployment.
 * @author Origin Protocol Inc
 */
abstract contract Initializable {
    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private initialized;

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

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(
            initializing || !initialized,
            "Initializable: contract is already initialized"
        );

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

        _;

        if (isTopLevelCall) {
            initializing = false;
        }
    }

    uint256[50] private ______gap;
}

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

/**
 * @title Base contract for vault strategies.
 * @author Origin Protocol Inc
 */
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

import { Initializable } from "../utils/Initializable.sol";
import { Governable } from "../governance/Governable.sol";
import { IVault } from "../interfaces/IVault.sol";

abstract contract InitializableAbstractStrategy is Initializable, Governable {
    using SafeERC20 for IERC20;

    event PTokenAdded(address indexed _asset, address _pToken);
    event PTokenRemoved(address indexed _asset, address _pToken);
    event Deposit(address indexed _asset, address _pToken, uint256 _amount);
    event Withdrawal(address indexed _asset, address _pToken, uint256 _amount);
    event RewardTokenCollected(
        address recipient,
        address rewardToken,
        uint256 amount
    );
    event RewardTokenAddressesUpdated(
        address[] _oldAddresses,
        address[] _newAddresses
    );
    event HarvesterAddressesUpdated(
        address _oldHarvesterAddress,
        address _newHarvesterAddress
    );

    /// @notice Address of the underlying platform
    address public immutable platformAddress;
    /// @notice Address of the OToken vault
    address public immutable vaultAddress;

    /// @dev Replaced with an immutable variable
    // slither-disable-next-line constable-states
    address private _deprecated_platformAddress;

    /// @dev Replaced with an immutable
    // slither-disable-next-line constable-states
    address private _deprecated_vaultAddress;

    /// @notice asset => pToken (Platform Specific Token Address)
    mapping(address => address) public assetToPToken;

    /// @notice Full list of all assets supported by the strategy
    address[] internal assetsMapped;

    // Deprecated: Reward token address
    // slither-disable-next-line constable-states
    address private _deprecated_rewardTokenAddress;

    // Deprecated: now resides in Harvester's rewardTokenConfigs
    // slither-disable-next-line constable-states
    uint256 private _deprecated_rewardLiquidationThreshold;

    /// @notice Address of the Harvester contract allowed to collect reward tokens
    address public harvesterAddress;

    /// @notice Address of the reward tokens. eg CRV, BAL, CVX, AURA
    address[] public rewardTokenAddresses;

    /* Reserved for future expansion. Used to be 100 storage slots
     * and has decreased to accommodate:
     * - harvesterAddress
     * - rewardTokenAddresses
     */
    int256[98] private _reserved;

    struct BaseStrategyConfig {
        address platformAddress; // Address of the underlying platform
        address vaultAddress; // Address of the OToken's Vault
    }

    /**
     * @param _config The platform and OToken vault addresses
     */
    constructor(BaseStrategyConfig memory _config) {
        platformAddress = _config.platformAddress;
        vaultAddress = _config.vaultAddress;
    }

    /**
     * @dev Internal initialize function, to set up initial internal state
     * @param _rewardTokenAddresses Address of reward token for platform
     * @param _assets Addresses of initial supported assets
     * @param _pTokens Platform Token corresponding addresses
     */
    function _initialize(
        address[] memory _rewardTokenAddresses,
        address[] memory _assets,
        address[] memory _pTokens
    ) internal {
        rewardTokenAddresses = _rewardTokenAddresses;

        uint256 assetCount = _assets.length;
        require(assetCount == _pTokens.length, "Invalid input arrays");
        for (uint256 i = 0; i < assetCount; ++i) {
            _setPTokenAddress(_assets[i], _pTokens[i]);
        }
    }

    /**
     * @notice Collect accumulated reward token and send to Vault.
     */
    function collectRewardTokens() external virtual onlyHarvester nonReentrant {
        _collectRewardTokens();
    }

    /**
     * @dev Default implementation that transfers reward tokens to the Harvester
     * Implementing strategies need to add custom logic to collect the rewards.
     */
    function _collectRewardTokens() internal virtual {
        uint256 rewardTokenCount = rewardTokenAddresses.length;
        for (uint256 i = 0; i < rewardTokenCount; ++i) {
            IERC20 rewardToken = IERC20(rewardTokenAddresses[i]);
            uint256 balance = rewardToken.balanceOf(address(this));
            if (balance > 0) {
                emit RewardTokenCollected(
                    harvesterAddress,
                    address(rewardToken),
                    balance
                );
                rewardToken.safeTransfer(harvesterAddress, balance);
            }
        }
    }

    /**
     * @dev Verifies that the caller is the Vault.
     */
    modifier onlyVault() {
        require(msg.sender == vaultAddress, "Caller is not the Vault");
        _;
    }

    /**
     * @dev Verifies that the caller is the Harvester.
     */
    modifier onlyHarvester() {
        require(msg.sender == harvesterAddress, "Caller is not the Harvester");
        _;
    }

    /**
     * @dev Verifies that the caller is the Vault or Governor.
     */
    modifier onlyVaultOrGovernor() {
        require(
            msg.sender == vaultAddress || msg.sender == governor(),
            "Caller is not the Vault or Governor"
        );
        _;
    }

    /**
     * @dev Verifies that the caller is the Vault, Governor, or Strategist.
     */
    modifier onlyVaultOrGovernorOrStrategist() {
        require(
            msg.sender == vaultAddress ||
                msg.sender == governor() ||
                msg.sender == IVault(vaultAddress).strategistAddr(),
            "Caller is not the Vault, Governor, or Strategist"
        );
        _;
    }

    /**
     * @notice Set the reward token addresses. Any old addresses will be overwritten.
     * @param _rewardTokenAddresses Array of reward token addresses
     */
    function setRewardTokenAddresses(address[] calldata _rewardTokenAddresses)
        external
        onlyGovernor
    {
        uint256 rewardTokenCount = _rewardTokenAddresses.length;
        for (uint256 i = 0; i < rewardTokenCount; ++i) {
            require(
                _rewardTokenAddresses[i] != address(0),
                "Can not set an empty address as a reward token"
            );
        }

        emit RewardTokenAddressesUpdated(
            rewardTokenAddresses,
            _rewardTokenAddresses
        );
        rewardTokenAddresses = _rewardTokenAddresses;
    }

    /**
     * @notice Get the reward token addresses.
     * @return address[] the reward token addresses.
     */
    function getRewardTokenAddresses()
        external
        view
        returns (address[] memory)
    {
        return rewardTokenAddresses;
    }

    /**
     * @notice Provide support for asset by passing its pToken address.
     *      This method can only be called by the system Governor
     * @param _asset    Address for the asset
     * @param _pToken   Address for the corresponding platform token
     */
    function setPTokenAddress(address _asset, address _pToken)
        external
        virtual
        onlyGovernor
    {
        _setPTokenAddress(_asset, _pToken);
    }

    /**
     * @notice Remove a supported asset by passing its index.
     *      This method can only be called by the system Governor
     * @param _assetIndex Index of the asset to be removed
     */
    function removePToken(uint256 _assetIndex) external virtual onlyGovernor {
        require(_assetIndex < assetsMapped.length, "Invalid index");
        address asset = assetsMapped[_assetIndex];
        address pToken = assetToPToken[asset];

        if (_assetIndex < assetsMapped.length - 1) {
            assetsMapped[_assetIndex] = assetsMapped[assetsMapped.length - 1];
        }
        assetsMapped.pop();
        assetToPToken[asset] = address(0);

        emit PTokenRemoved(asset, pToken);
    }

    /**
     * @notice Provide support for asset by passing its pToken address.
     *      Add to internal mappings and execute the platform specific,
     * abstract method `_abstractSetPToken`
     * @param _asset    Address for the asset
     * @param _pToken   Address for the corresponding platform token
     */
    function _setPTokenAddress(address _asset, address _pToken) internal {
        require(assetToPToken[_asset] == address(0), "pToken already set");
        require(
            _asset != address(0) && _pToken != address(0),
            "Invalid addresses"
        );

        assetToPToken[_asset] = _pToken;
        assetsMapped.push(_asset);

        emit PTokenAdded(_asset, _pToken);

        _abstractSetPToken(_asset, _pToken);
    }

    /**
     * @notice Transfer token to governor. Intended for recovering tokens stuck in
     *      strategy contracts, i.e. mistaken sends.
     * @param _asset Address for the asset
     * @param _amount Amount of the asset to transfer
     */
    function transferToken(address _asset, uint256 _amount)
        public
        onlyGovernor
    {
        require(!supportsAsset(_asset), "Cannot transfer supported asset");
        IERC20(_asset).safeTransfer(governor(), _amount);
    }

    /**
     * @notice Set the Harvester contract that can collect rewards.
     * @param _harvesterAddress Address of the harvester contract.
     */
    function setHarvesterAddress(address _harvesterAddress)
        external
        onlyGovernor
    {
        emit HarvesterAddressesUpdated(harvesterAddress, _harvesterAddress);
        harvesterAddress = _harvesterAddress;
    }

    /***************************************
                 Abstract
    ****************************************/

    function _abstractSetPToken(address _asset, address _pToken)
        internal
        virtual;

    function safeApproveAllTokens() external virtual;

    /**
     * @notice Deposit an amount of assets into the platform
     * @param _asset               Address for the asset
     * @param _amount              Units of asset to deposit
     */
    function deposit(address _asset, uint256 _amount) external virtual;

    /**
     * @notice Deposit all supported assets in this strategy contract to the platform
     */
    function depositAll() external virtual;

    /**
     * @notice Withdraw an `amount` of assets from the platform and
     * send to the `_recipient`.
     * @param _recipient         Address to which the asset should be sent
     * @param _asset             Address of the asset
     * @param _amount            Units of asset to withdraw
     */
    function withdraw(
        address _recipient,
        address _asset,
        uint256 _amount
    ) external virtual;

    /**
     * @notice Withdraw all supported assets from platform and
     * sends to the OToken's Vault.
     */
    function withdrawAll() external virtual;

    /**
     * @notice Get the total asset value held in the platform.
     *      This includes any interest that was generated since depositing.
     * @param _asset      Address of the asset
     * @return balance    Total value of the asset in the platform
     */
    function checkBalance(address _asset)
        external
        view
        virtual
        returns (uint256 balance);

    /**
     * @notice Check if an asset is supported.
     * @param _asset    Address of the asset
     * @return bool     Whether asset is supported
     */
    function supportsAsset(address _asset) public view virtual returns (bool);
}

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

import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/**
 * @dev Optional functions from the ERC20 standard.
 * Converted from openzeppelin/contracts/token/ERC20/ERC20Detailed.sol
 * @author Origin Protocol Inc
 */
abstract contract InitializableERC20Detailed is IERC20 {
    // Storage gap to skip storage from prior to OUSD reset
    uint256[100] private _____gap;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for `name`, `symbol`, and `decimals`. All three of
     * these values are immutable: they can only be set once during
     * construction.
     * @notice To avoid variable shadowing appended `Arg` after arguments name.
     */
    function _initialize(
        string memory nameArg,
        string memory symbolArg,
        uint8 decimalsArg
    ) internal {
        _name = nameArg;
        _symbol = symbolArg;
        _decimals = decimalsArg;
    }

    /**
     * @notice Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @notice Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @notice Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

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

import { IERC20, InitializableAbstractStrategy } from "../utils/InitializableAbstractStrategy.sol";
import { IWETH9 } from "../interfaces/IWETH9.sol";
import { IVault } from "../interfaces/IVault.sol";

interface IStETHWithdrawal {
    event WithdrawalRequested(
        uint256 indexed requestId,
        address indexed requestor,
        address indexed owner,
        uint256 amountOfStETH,
        uint256 amountOfShares
    );
    event WithdrawalsFinalized(
        uint256 indexed from,
        uint256 indexed to,
        uint256 amountOfETHLocked,
        uint256 sharesToBurn,
        uint256 timestamp
    );
    event WithdrawalClaimed(
        uint256 indexed requestId,
        address indexed owner,
        address indexed receiver,
        uint256 amountOfETH
    );

    struct WithdrawalRequestStatus {
        /// @notice stETH token amount that was locked on withdrawal queue for this request
        uint256 amountOfStETH;
        /// @notice amount of stETH shares locked on withdrawal queue for this request
        uint256 amountOfShares;
        /// @notice address that can claim or transfer this request
        address owner;
        /// @notice timestamp of when the request was created, in seconds
        uint256 timestamp;
        /// @notice true, if request is finalized
        bool isFinalized;
        /// @notice true, if request is claimed. Request is claimable if (isFinalized && !isClaimed)
        bool isClaimed;
    }

    function requestWithdrawals(uint256[] calldata _amounts, address _owner)
        external
        returns (uint256[] memory requestIds);

    function getLastCheckpointIndex() external view returns (uint256);

    function findCheckpointHints(
        uint256[] calldata _requestIds,
        uint256 _firstIndex,
        uint256 _lastIndex
    ) external view returns (uint256[] memory hintIds);

    function claimWithdrawals(
        uint256[] calldata _requestIds,
        uint256[] calldata _hints
    ) external;

    function getWithdrawalStatus(uint256[] calldata _requestIds)
        external
        view
        returns (WithdrawalRequestStatus[] memory statuses);

    function getWithdrawalRequests(address _owner)
        external
        view
        returns (uint256[] memory requestsIds);

    function finalize(
        uint256 _lastRequestIdToBeFinalized,
        uint256 _maxShareRate
    ) external payable;
}

/**
 * @title Lido Withdrawal Strategy
 * @notice This strategy withdraws ETH from stETH via the Lido Withdrawal Queue contract
 * @author Origin Protocol Inc
 */
contract LidoWithdrawalStrategy is InitializableAbstractStrategy {
    /// @notice Address of the WETH token
    IWETH9 private constant weth =
        IWETH9(0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2);
    /// @notice Address of the stETH token
    IERC20 private constant stETH =
        IERC20(0xae7ab96520DE3A18E5e111B5EaAb095312D7fE84);
    /// @notice Address of the Lido Withdrawal Queue contract
    IStETHWithdrawal private constant withdrawalQueue =
        IStETHWithdrawal(0x889edC2eDab5f40e902b864aD4d7AdE8E412F9B1);
    /// @notice Maximum amount of stETH that can be withdrawn in a single request
    uint256 public constant MaxWithdrawalAmount = 1000 ether;
    /// @notice Total amount of stETH that has been requested to be withdrawn for ETH
    uint256 public outstandingWithdrawals;

    event WithdrawalRequests(uint256[] requestIds, uint256[] amounts);
    event WithdrawalClaims(uint256[] requestIds, uint256 amount);

    constructor(BaseStrategyConfig memory _stratConfig)
        InitializableAbstractStrategy(_stratConfig)
    {}

    /**
     * @notice initialize function, to set up initial internal state
     * @param _rewardTokenAddresses Address of reward token for platform
     * @param _assets Addresses of initial supported assets
     * @param _pTokens Platform Token corresponding addresses
     */
    function initialize(
        address[] memory _rewardTokenAddresses,
        address[] memory _assets,
        address[] memory _pTokens
    ) external onlyGovernor initializer {
        InitializableAbstractStrategy._initialize(
            _rewardTokenAddresses,
            _assets,
            _pTokens
        );
        safeApproveAllTokens();
    }

    /**
     * @notice deposit() function not used for this strategy. Use depositAll() instead.
     */
    function deposit(address, uint256) public override onlyVault nonReentrant {
        // This method no longer used by the VaultAdmin, and we don't want it
        // to be used by VaultCore.
        require(false, "use depositAll() instead");
    }

    /**
     * @notice Takes all given stETH and creates Lido withdrawal request
     */
    function depositAll() external override onlyVault nonReentrant {
        uint256 stETHStart = stETH.balanceOf(address(this));
        require(stETHStart > 0, "No stETH to withdraw");

        uint256 withdrawalLength = (stETHStart / MaxWithdrawalAmount) + 1;
        uint256[] memory amounts = new uint256[](withdrawalLength);

        uint256 stETHRemaining = stETHStart;
        uint256 i = 0;
        while (stETHRemaining > MaxWithdrawalAmount) {
            amounts[i++] = MaxWithdrawalAmount;
            stETHRemaining -= MaxWithdrawalAmount;
        }
        amounts[i] = stETHRemaining;

        uint256[] memory requestIds = withdrawalQueue.requestWithdrawals(
            amounts,
            address(this)
        );

        emit WithdrawalRequests(requestIds, amounts);

        // Is there any stETH left except 1 wei from each request?
        // This is because stETH does not transfer all the transfer amount.
        uint256 stEthDust = stETH.balanceOf(address(this));
        require(
            stEthDust <= withdrawalLength,
            "Not all stEth in withdraw queue"
        );
        outstandingWithdrawals += stETHStart;

        // This strategy claims to support WETH, so it is possible for
        // the vault to transfer WETH to it. This returns any deposited WETH
        // to the vault so that it is not lost for balance tracking purposes.
        uint256 wethBalance = weth.balanceOf(address(this));
        if (wethBalance > 0) {
            // slither-disable-next-line unchecked-transfer
            weth.transfer(vaultAddress, wethBalance);
        }

        emit Deposit(address(stETH), address(withdrawalQueue), stETHStart);
    }

    /**
     * @notice Withdraw an asset from the underlying platform
     * @param _recipient Address to receive withdrawn assets
     * @param _asset Address of the asset to withdraw
     * @param _amount Amount of assets to withdraw
     */
    function withdraw(
        // solhint-disable-next-line no-unused-vars
        address _recipient,
        // solhint-disable-next-line no-unused-vars
        address _asset,
        // solhint-disable-next-line no-unused-vars
        uint256 _amount
    ) external override onlyVault nonReentrant {
        // Does nothing - all withdrawals need to be called manually using the
        // Strategist calling claimWithdrawals
        revert("use claimWithdrawals()");
    }

    /**
     * @notice Claim previously requested withdrawals that have now finalized.
     * Called by the Strategist.
     * @param _requestIds Array of withdrawal request identifiers
     * @param _expectedAmount Total amount of ETH expect to be withdrawn
     */
    function claimWithdrawals(
        uint256[] memory _requestIds,
        uint256 _expectedAmount
    ) external nonReentrant {
        require(
            msg.sender == IVault(vaultAddress).strategistAddr(),
            "Caller is not the Strategist"
        );
        uint256 startingBalance = payable(address(this)).balance;
        uint256 lastIndex = withdrawalQueue.getLastCheckpointIndex();
        uint256[] memory hintIds = withdrawalQueue.findCheckpointHints(
            _requestIds,
            1,
            lastIndex
        );
        withdrawalQueue.claimWithdrawals(_requestIds, hintIds);

        uint256 currentBalance = payable(address(this)).balance;
        uint256 withdrawalAmount = currentBalance - startingBalance;
        // Withdrawal amount should be within 2 wei of expected amount
        require(
            withdrawalAmount + 2 >= _expectedAmount &&
                withdrawalAmount <= _expectedAmount,
            "Withdrawal amount not expected"
        );

        emit WithdrawalClaims(_requestIds, withdrawalAmount);

        outstandingWithdrawals -= withdrawalAmount;
        weth.deposit{ value: currentBalance }();
        // slither-disable-next-line unchecked-transfer
        weth.transfer(vaultAddress, currentBalance);
        emit Withdrawal(
            address(weth),
            address(withdrawalQueue),
            currentBalance
        );
    }

    /**
     * @notice Withdraw all assets from this strategy, and transfer to the Vault.
     * In correct operation, this strategy should never hold any assets.
     */
    function withdrawAll() external override onlyVaultOrGovernor nonReentrant {
        if (payable(address(this)).balance > 0) {
            weth.deposit{ value: payable(address(this)).balance }();
        }
        uint256 wethBalance = weth.balanceOf(address(this));
        if (wethBalance > 0) {
            // slither-disable-next-line unchecked-transfer
            weth.transfer(vaultAddress, wethBalance);
            emit Withdrawal(address(weth), address(0), wethBalance);
        }
        uint256 stEthBalance = stETH.balanceOf(address(this));
        if (stEthBalance > 0) {
            // slither-disable-next-line unchecked-transfer
            stETH.transfer(vaultAddress, stEthBalance);
            emit Withdrawal(address(stETH), address(0), stEthBalance);
        }
    }

    /**
     * @notice Returns the amount of queued stETH that will be returned as WETH.
     * We return this as a WETH asset, since that is what it will eventually be returned as.
     * We only return the outstandingWithdrawals, because the contract itself should never hold any funds.
     * @param _asset      Address of the asset
     * @return balance    Total value of the asset in the platform
     */
    function checkBalance(address _asset)
        external
        view
        override
        returns (uint256 balance)
    {
        if (_asset == address(weth)) {
            return outstandingWithdrawals;
        } else if (_asset == address(stETH)) {
            return 0;
        } else {
            revert("Unexpected asset address");
        }
    }

    /**
     * @notice Approve the spending of all assets by their corresponding cToken,
     *      if for some reason is it necessary.
     */
    function safeApproveAllTokens() public override {
        // slither-disable-next-line unused-return
        stETH.approve(address(withdrawalQueue), type(uint256).max);
    }

    /**
     * @notice Check if an asset is supported.
     * @param _asset    Address of the asset
     * @return bool     Whether asset is supported
     */
    function supportsAsset(address _asset) public pure override returns (bool) {
        // stETH can be deposited by the vault and balances are reported in WETH
        return _asset == address(stETH) || _asset == address(weth);
    }

    /// @notice Needed to receive ETH when withdrawal requests are claimed
    receive() external payable {}

    function _abstractSetPToken(address, address) internal pure override {
        revert("No pTokens are used");
    }
}

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

/**
 * @title OUSD Token Contract
 * @dev ERC20 compatible contract for OUSD
 * @dev Implements an elastic supply
 * @author Origin Protocol Inc
 */
import { SafeMath } from "@openzeppelin/contracts/utils/math/SafeMath.sol";
import { Address } from "@openzeppelin/contracts/utils/Address.sol";

import { Initializable } from "../utils/Initializable.sol";
import { InitializableERC20Detailed } from "../utils/InitializableERC20Detailed.sol";
import { StableMath } from "../utils/StableMath.sol";
import { Governable } from "../governance/Governable.sol";

/**
 * NOTE that this is an ERC20 token but the invariant that the sum of
 * balanceOf(x) for all x is not >= totalSupply(). This is a consequence of the
 * rebasing design. Any integrations with OUSD should be aware.
 */

contract OUSD is Initializable, InitializableERC20Detailed, Governable {
    using SafeMath for uint256;
    using StableMath for uint256;

    event TotalSupplyUpdatedHighres(
        uint256 totalSupply,
        uint256 rebasingCredits,
        uint256 rebasingCreditsPerToken
    );
    event AccountRebasingEnabled(address account);
    event AccountRebasingDisabled(address account);

    enum RebaseOptions {
        NotSet,
        OptOut,
        OptIn
    }

    uint256 private constant MAX_SUPPLY = ~uint128(0); // (2^128) - 1
    uint256 public _totalSupply;
    mapping(address => mapping(address => uint256)) private _allowances;
    address public vaultAddress = address(0);
    mapping(address => uint256) private _creditBalances;
    uint256 private _rebasingCredits;
    uint256 private _rebasingCreditsPerToken;
    // Frozen address/credits are non rebasing (value is held in contracts which
    // do not receive yield unless they explicitly opt in)
    uint256 public nonRebasingSupply;
    mapping(address => uint256) public nonRebasingCreditsPerToken;
    mapping(address => RebaseOptions) public rebaseState;
    mapping(address => uint256) public isUpgraded;

    uint256 private constant RESOLUTION_INCREASE = 1e9;

    function initialize(
        string calldata _nameArg,
        string calldata _symbolArg,
        address _vaultAddress,
        uint256 _initialCreditsPerToken
    ) external onlyGovernor initializer {
        InitializableERC20Detailed._initialize(_nameArg, _symbolArg, 18);
        _rebasingCreditsPerToken = _initialCreditsPerToken;
        vaultAddress = _vaultAddress;
    }

    /**
     * @dev Verifies that the caller is the Vault contract
     */
    modifier onlyVault() {
        require(vaultAddress == msg.sender, "Caller is not the Vault");
        _;
    }

    /**
     * @return The total supply of OUSD.
     */
    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @return Low resolution rebasingCreditsPerToken
     */
    function rebasingCreditsPerToken() public view returns (uint256) {
        return _rebasingCreditsPerToken / RESOLUTION_INCREASE;
    }

    /**
     * @return Low resolution total number of rebasing credits
     */
    function rebasingCredits() public view returns (uint256) {
        return _rebasingCredits / RESOLUTION_INCREASE;
    }

    /**
     * @return High resolution rebasingCreditsPerToken
     */
    function rebasingCreditsPerTokenHighres() public view returns (uint256) {
        return _rebasingCreditsPerToken;
    }

    /**
     * @return High resolution total number of rebasing credits
     */
    function rebasingCreditsHighres() public view returns (uint256) {
        return _rebasingCredits;
    }

    /**
     * @dev Gets the balance of the specified address.
     * @param _account Address to query the balance of.
     * @return A uint256 representing the amount of base units owned by the
     *         specified address.
     */
    function balanceOf(address _account)
        public
        view
        override
        returns (uint256)
    {
        if (_creditBalances[_account] == 0) return 0;
        return
            _creditBalances[_account].divPrecisely(_creditsPerToken(_account));
    }

    /**
     * @dev Gets the credits balance of the specified address.
     * @dev Backwards compatible with old low res credits per token.
     * @param _account The address to query the balance of.
     * @return (uint256, uint256) Credit balance and credits per token of the
     *         address
     */
    function creditsBalanceOf(address _account)
        public
        view
        returns (uint256, uint256)
    {
        uint256 cpt = _creditsPerToken(_account);
        if (cpt == 1e27) {
            // For a period before the resolution upgrade, we created all new
            // contract accounts at high resolution. Since they are not changing
            // as a result of this upgrade, we will return their true values
            return (_creditBalances[_account], cpt);
        } else {
            return (
                _creditBalances[_account] / RESOLUTION_INCREASE,
                cpt / RESOLUTION_INCREASE
            );
        }
    }

    /**
     * @dev Gets the credits balance of the specified address.
     * @param _account The address to query the balance of.
     * @return (uint256, uint256, bool) Credit balance, credits per token of the
     *         address, and isUpgraded
     */
    function creditsBalanceOfHighres(address _account)
        public
        view
        returns (
            uint256,
            uint256,
            bool
        )
    {
        return (
            _creditBalances[_account],
            _creditsPerToken(_account),
            isUpgraded[_account] == 1
        );
    }

    /**
     * @dev Transfer tokens to a specified address.
     * @param _to the address to transfer to.
     * @param _value the amount to be transferred.
     * @return true on success.
     */
    function transfer(address _to, uint256 _value)
        public
        override
        returns (bool)
    {
        require(_to != address(0), "Transfer to zero address");
        require(
            _value <= balanceOf(msg.sender),
            "Transfer greater than balance"
        );

        _executeTransfer(msg.sender, _to, _value);

        emit Transfer(msg.sender, _to, _value);

        return true;
    }

    /**
     * @dev Transfer tokens from one address to another.
     * @param _from The address you want to send tokens from.
     * @param _to The address you want to transfer to.
     * @param _value The amount of tokens to be transferred.
     */
    function transferFrom(
        address _from,
        address _to,
        uint256 _value
    ) public override returns (bool) {
        require(_to != address(0), "Transfer to zero address");
        require(_value <= balanceOf(_from), "Transfer greater than balance");

        _allowances[_from][msg.sender] = _allowances[_from][msg.sender].sub(
            _value
        );

        _executeTransfer(_from, _to, _value);

        emit Transfer(_from, _to, _value);

        return true;
    }

    /**
     * @dev Update the count of non rebasing credits in response to a transfer
     * @param _from The address you want to send tokens from.
     * @param _to The address you want to transfer to.
     * @param _value Amount of OUSD to transfer
     */
    function _executeTransfer(
        address _from,
        address _to,
        uint256 _value
    ) internal {
        bool isNonRebasingTo = _isNonRebasingAccount(_to);
        bool isNonRebasingFrom = _isNonRebasingAccount(_from);

        // Credits deducted and credited might be different due to the
        // differing creditsPerToken used by each account
        uint256 creditsCredited = _value.mulTruncate(_creditsPerToken(_to));
        uint256 creditsDeducted = _value.mulTruncate(_creditsPerToken(_from));

        _creditBalances[_from] = _creditBalances[_from].sub(
            creditsDeducted,
            "Transfer amount exceeds balance"
        );
        _creditBalances[_to] = _creditBalances[_to].add(creditsCredited);

        if (isNonRebasingTo && !isNonRebasingFrom) {
            // Transfer to non-rebasing account from rebasing account, credits
            // are removed from the non rebasing tally
            nonRebasingSupply = nonRebasingSupply.add(_value);
            // Update rebasingCredits by subtracting the deducted amount
            _rebasingCredits = _rebasingCredits.sub(creditsDeducted);
        } else if (!isNonRebasingTo && isNonRebasingFrom) {
            // Transfer to rebasing account from non-rebasing account
            // Decreasing non-rebasing credits by the amount that was sent
            nonRebasingSupply = nonRebasingSupply.sub(_value);
            // Update rebasingCredits by adding the credited amount
            _rebasingCredits = _rebasingCredits.add(creditsCredited);
        }
    }

    /**
     * @dev Function to check the amount of tokens that _owner has allowed to
     *      `_spender`.
     * @param _owner The address which owns the funds.
     * @param _spender The address which will spend the funds.
     * @return The number of tokens still available for the _spender.
     */
    function allowance(address _owner, address _spender)
        public
        view
        override
        returns (uint256)
    {
        return _allowances[_owner][_spender];
    }

    /**
     * @dev Approve the passed address to spend the specified amount of tokens
     *      on behalf of msg.sender. This method is included for ERC20
     *      compatibility. `increaseAllowance` and `decreaseAllowance` should be
     *      used instead.
     *
     *      Changing an allowance with this method brings the risk that someone
     *      may transfer both the old and the new allowance - if they are both
     *      greater than zero - if a transfer transaction is mined before the
     *      later approve() call is mined.
     * @param _spender The address which will spend the funds.
     * @param _value The amount of tokens to be spent.
     */
    function approve(address _spender, uint256 _value)
        public
        override
        returns (bool)
    {
        _allowances[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
     * @dev Increase the amount of tokens that an owner has allowed to
     *      `_spender`.
     *      This method should be used instead of approve() to avoid the double
     *      approval vulnerability described above.
     * @param _spender The address which will spend the funds.
     * @param _addedValue The amount of tokens to increase the allowance by.
     */
    function increaseAllowance(address _spender, uint256 _addedValue)
        public
        returns (bool)
    {
        _allowances[msg.sender][_spender] = _allowances[msg.sender][_spender]
            .add(_addedValue);
        emit Approval(msg.sender, _spender, _allowances[msg.sender][_spender]);
        return true;
    }

    /**
     * @dev Decrease the amount of tokens that an owner has allowed to
            `_spender`.
     * @param _spender The address which will spend the funds.
     * @param _subtractedValue The amount of tokens to decrease the allowance
     *        by.
     */
    function decreaseAllowance(address _spender, uint256 _subtractedValue)
        public
        returns (bool)
    {
        uint256 oldValue = _allowances[msg.sender][_spender];
        if (_subtractedValue >= oldValue) {
            _allowances[msg.sender][_spender] = 0;
        } else {
            _allowances[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }
        emit Approval(msg.sender, _spender, _allowances[msg.sender][_spender]);
        return true;
    }

    /**
     * @dev Mints new tokens, increasing totalSupply.
     */
    function mint(address _account, uint256 _amount) external onlyVault {
        _mint(_account, _amount);
    }

    /**
     * @dev Creates `_amount` tokens and assigns them to `_account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address _account, uint256 _amount) internal nonReentrant {
        require(_account != address(0), "Mint to the zero address");

        bool isNonRebasingAccount = _isNonRebasingAccount(_account);

        uint256 creditAmount = _amount.mulTruncate(_creditsPerToken(_account));
        _creditBalances[_account] = _creditBalances[_account].add(creditAmount);

        // If the account is non rebasing and doesn't have a set creditsPerToken
        // then set it i.e. this is a mint from a fresh contract
        if (isNonRebasingAccount) {
            nonRebasingSupply = nonRebasingSupply.add(_amount);
        } else {
            _rebasingCredits = _rebasingCredits.add(creditAmount);
        }

        _totalSupply = _totalSupply.add(_amount);

        require(_totalSupply < MAX_SUPPLY, "Max supply");

        emit Transfer(address(0), _account, _amount);
    }

    /**
     * @dev Burns tokens, decreasing totalSupply.
     */
    function burn(address account, uint256 amount) external onlyVault {
        _burn(account, amount);
    }

    /**
     * @dev Destroys `_amount` tokens from `_account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `_account` cannot be the zero address.
     * - `_account` must have at least `_amount` tokens.
     */
    function _burn(address _account, uint256 _amount) internal nonReentrant {
        require(_account != address(0), "Burn from the zero address");
        if (_amount == 0) {
            return;
        }

        bool isNonRebasingAccount = _isNonRebasingAccount(_account);
        uint256 creditAmount = _amount.mulTruncate(_creditsPerToken(_account));
        uint256 currentCredits = _creditBalances[_account];

        // Remove the credits, burning rounding errors
        if (
            currentCredits == creditAmount || currentCredits - 1 == creditAmount
        ) {
            // Handle dust from rounding
            _creditBalances[_account] = 0;
        } else if (currentCredits > creditAmount) {
            _creditBalances[_account] = _creditBalances[_account].sub(
                creditAmount
            );
        } else {
            revert("Remove exceeds balance");
        }

        // Remove from the credit tallies and non-rebasing supply
        if (isNonRebasingAccount) {
            nonRebasingSupply = nonRebasingSupply.sub(_amount);
        } else {
            _rebasingCredits = _rebasingCredits.sub(creditAmount);
        }

        _totalSupply = _totalSupply.sub(_amount);

        emit Transfer(_account, address(0), _amount);
    }

    /**
     * @dev Get the credits per token for an account. Returns a fixed amount
     *      if the account is non-rebasing.
     * @param _account Address of the account.
     */
    function _creditsPerToken(address _account)
        internal
        view
        returns (uint256)
    {
        if (nonRebasingCreditsPerToken[_account] != 0) {
            return nonRebasingCreditsPerToken[_account];
        } else {
            return _rebasingCreditsPerToken;
        }
    }

    /**
     * @dev Is an account using rebasing accounting or non-rebasing accounting?
     *      Also, ensure contracts are non-rebasing if they have not opted in.
     * @param _account Address of the account.
     */
    function _isNonRebasingAccount(address _account) internal returns (bool) {
        bool isContract = Address.isContract(_account);
        if (isContract && rebaseState[_account] == RebaseOptions.NotSet) {
            _ensureRebasingMigration(_account);
        }
        return nonRebasingCreditsPerToken[_account] > 0;
    }

    /**
     * @dev Ensures internal account for rebasing and non-rebasing credits and
     *      supply is updated following deployment of frozen yield change.
     */
    function _ensureRebasingMigration(address _account) internal {
        if (nonRebasingCreditsPerToken[_account] == 0) {
            emit AccountRebasingDisabled(_account);
            if (_creditBalances[_account] == 0) {
                // Since there is no existing balance, we can directly set to
                // high resolution, and do not have to do any other bookkeeping
                nonRebasingCreditsPerToken[_account] = 1e27;
            } else {
                // Migrate an existing account:

                // Set fixed credits per token for this account
                nonRebasingCreditsPerToken[_account] = _rebasingCreditsPerToken;
                // Update non rebasing supply
                nonRebasingSupply = nonRebasingSupply.add(balanceOf(_account));
                // Update credit tallies
                _rebasingCredits = _rebasingCredits.sub(
                    _creditBalances[_account]
                );
            }
        }
    }

    /**
     * @notice Enable rebasing for an account.
     * @dev Add a contract address to the non-rebasing exception list. The
     * address's balance will be part of rebases and the account will be exposed
     * to upside and downside.
     * @param _account Address of the account.
     */
    function governanceRebaseOptIn(address _account)
        public
        nonReentrant
        onlyGovernor
    {
        _rebaseOptIn(_account);
    }

    /**
     * @dev Add a contract address to the non-rebasing exception list. The
     * address's balance will be part of rebases and the account will be exposed
     * to upside and downside.
     */
    function rebaseOptIn() public nonReentrant {
        _rebaseOptIn(msg.sender);
    }

    function _rebaseOptIn(address _account) internal {
        require(_isNonRebasingAccount(_account), "Account has not opted out");

        // Convert balance into the same amount at the current exchange rate
        uint256 newCreditBalance = _creditBalances[_account]
            .mul(_rebasingCreditsPerToken)
            .div(_creditsPerToken(_account));

        // Decreasing non rebasing supply
        nonRebasingSupply = nonRebasingSupply.sub(balanceOf(_account));

        _creditBalances[_account] = newCreditBalance;

        // Increase rebasing credits, totalSupply remains unchanged so no
        // adjustment necessary
        _rebasingCredits = _rebasingCredits.add(_creditBalances[_account]);

        rebaseState[_account] = RebaseOptions.OptIn;

        // Delete any fixed credits per token
        delete nonRebasingCreditsPerToken[_account];
        emit AccountRebasingEnabled(_account);
    }

    /**
     * @dev Explicitly mark that an address is non-rebasing.
     */
    function rebaseOptOut() public nonReentrant {
        require(!_isNonRebasingAccount(msg.sender), "Account has not opted in");

        // Increase non rebasing supply
        nonRebasingSupply = nonRebasingSupply.add(balanceOf(msg.sender));
        // Set fixed credits per token
        nonRebasingCreditsPerToken[msg.sender] = _rebasingCreditsPerToken;

        // Decrease rebasing credits, total supply remains unchanged so no
        // adjustment necessary
        _rebasingCredits = _rebasingCredits.sub(_creditBalances[msg.sender]);

        // Mark explicitly opted out of rebasing
        rebaseState[msg.sender] = RebaseOptions.OptOut;
        emit AccountRebasingDisabled(msg.sender);
    }

    /**
     * @dev Modify the supply without minting new tokens. This uses a change in
     *      the exchange rate between "credits" and OUSD tokens to change balances.
     * @param _newTotalSupply New total supply of OUSD.
     */
    function changeSupply(uint256 _newTotalSupply)
        external
        onlyVault
        nonReentrant
    {
        require(_totalSupply > 0, "Cannot increase 0 supply");

        if (_totalSupply == _newTotalSupply) {
            emit TotalSupplyUpdatedHighres(
                _totalSupply,
                _rebasingCredits,
                _rebasingCreditsPerToken
            );
            return;
        }

        _totalSupply = _newTotalSupply > MAX_SUPPLY
            ? MAX_SUPPLY
            : _newTotalSupply;

        _rebasingCreditsPerToken = _rebasingCredits.divPrecisely(
            _totalSupply.sub(nonRebasingSupply)
        );

        require(_rebasingCreditsPerToken > 0, "Invalid change in supply");

        _totalSupply = _rebasingCredits
            .divPrecisely(_rebasingCreditsPerToken)
            .add(nonRebasingSupply);

        emit TotalSupplyUpdatedHighres(
            _totalSupply,
            _rebasingCredits,
            _rebasingCreditsPerToken
        );
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.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;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    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));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    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");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @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");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

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

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

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

import { SafeMath } from "@openzeppelin/contracts/utils/math/SafeMath.sol";

// Based on StableMath from Stability Labs Pty. Ltd.
// https://github.com/mstable/mStable-contracts/blob/master/contracts/shared/StableMath.sol

library StableMath {
    using SafeMath for uint256;

    /**
     * @dev Scaling unit for use in specific calculations,
     * where 1 * 10**18, or 1e18 represents a unit '1'
     */
    uint256 private constant FULL_SCALE = 1e18;

    /***************************************
                    Helpers
    ****************************************/

    /**
     * @dev Adjust the scale of an integer
     * @param to Decimals to scale to
     * @param from Decimals to scale from
     */
    function scaleBy(
        uint256 x,
        uint256 to,
        uint256 from
    ) internal pure returns (uint256) {
        if (to > from) {
            x = x.mul(10**(to - from));
        } else if (to < from) {
            // slither-disable-next-line divide-before-multiply
            x = x.div(10**(from - to));
        }
        return x;
    }

    /***************************************
               Precise Arithmetic
    ****************************************/

    /**
     * @dev Multiplies two precise units, and then truncates by the full scale
     * @param x Left hand input to multiplication
     * @param y Right hand input to multiplication
     * @return Result after multiplying the two inputs and then dividing by the shared
     *         scale unit
     */
    function mulTruncate(uint256 x, uint256 y) internal pure returns (uint256) {
        return mulTruncateScale(x, y, FULL_SCALE);
    }

    /**
     * @dev Multiplies two precise units, and then truncates by the given scale. For example,
     * when calculating 90% of 10e18, (10e18 * 9e17) / 1e18 = (9e36) / 1e18 = 9e18
     * @param x Left hand input to multiplication
     * @param y Right hand input to multiplication
     * @param scale Scale unit
     * @return Result after multiplying the two inputs and then dividing by the shared
     *         scale unit
     */
    function mulTruncateScale(
        uint256 x,
        uint256 y,
        uint256 scale
    ) internal pure returns (uint256) {
        // e.g. assume scale = fullScale
        // z = 10e18 * 9e17 = 9e36
        uint256 z = x.mul(y);
        // return 9e36 / 1e18 = 9e18
        return z.div(scale);
    }

    /**
     * @dev Multiplies two precise units, and then truncates by the full scale, rounding up the result
     * @param x Left hand input to multiplication
     * @param y Right hand input to multiplication
     * @return Result after multiplying the two inputs and then dividing by the shared
     *          scale unit, rounded up to the closest base unit.
     */
    function mulTruncateCeil(uint256 x, uint256 y)
        internal
        pure
        returns (uint256)
    {
        // e.g. 8e17 * 17268172638 = 138145381104e17
        uint256 scaled = x.mul(y);
        // e.g. 138145381104e17 + 9.99...e17 = 138145381113.99...e17
        uint256 ceil = scaled.add(FULL_SCALE.sub(1));
        // e.g. 13814538111.399...e18 / 1e18 = 13814538111
        return ceil.div(FULL_SCALE);
    }

    /**
     * @dev Precisely divides two units, by first scaling the left hand operand. Useful
     *      for finding percentage weightings, i.e. 8e18/10e18 = 80% (or 8e17)
     * @param x Left hand input to division
     * @param y Right hand input to division
     * @return Result after multiplying the left operand by the scale, and
     *         executing the division on the right hand input.
     */
    function divPrecisely(uint256 x, uint256 y)
        internal
        pure
        returns (uint256)
    {
        // e.g. 8e18 * 1e18 = 8e36
        uint256 z = x.mul(FULL_SCALE);
        // e.g. 8e36 / 10e18 = 8e17
        return z.div(y);
    }
}

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

/**
 * @title OToken VaultStorage contract
 * @notice The VaultStorage contract defines the storage for the Vault contracts
 * @author Origin Protocol Inc
 */

import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import { Address } from "@openzeppelin/contracts/utils/Address.sol";

import { IStrategy } from "../interfaces/IStrategy.sol";
import { Governable } from "../governance/Governable.sol";
import { OUSD } from "../token/OUSD.sol";
import { Initializable } from "../utils/Initializable.sol";
import "../utils/Helpers.sol";

contract VaultStorage is Initializable, Governable {
    using SafeERC20 for IERC20;

    event AssetSupported(address _asset);
    event AssetRemoved(address _asset);
    event AssetDefaultStrategyUpdated(address _asset, address _strategy);
    event AssetAllocated(address _asset, address _strategy, uint256 _amount);
    event StrategyApproved(address _addr);
    event StrategyRemoved(address _addr);
    event Mint(address _addr, uint256 _value);
    event Redeem(address _addr, uint256 _value);
    event CapitalPaused();
    event CapitalUnpaused();
    event RebasePaused();
    event RebaseUnpaused();
    event VaultBufferUpdated(uint256 _vaultBuffer);
    event OusdMetaStrategyUpdated(address _ousdMetaStrategy);
    event RedeemFeeUpdated(uint256 _redeemFeeBps);
    event PriceProviderUpdated(address _priceProvider);
    event AllocateThresholdUpdated(uint256 _threshold);
    event RebaseThresholdUpdated(uint256 _threshold);
    event StrategistUpdated(address _address);
    event MaxSupplyDiffChanged(uint256 maxSupplyDiff);
    event YieldDistribution(address _to, uint256 _yield, uint256 _fee);
    event TrusteeFeeBpsChanged(uint256 _basis);
    event TrusteeAddressChanged(address _address);
    event NetOusdMintForStrategyThresholdChanged(uint256 _threshold);
    event SwapperChanged(address _address);
    event SwapAllowedUndervalueChanged(uint256 _basis);
    event SwapSlippageChanged(address _asset, uint256 _basis);
    event Swapped(
        address indexed _fromAsset,
        address indexed _toAsset,
        uint256 _fromAssetAmount,
        uint256 _toAssetAmount
    );

    // Assets supported by the Vault, i.e. Stablecoins
    enum UnitConversion {
        DECIMALS,
        GETEXCHANGERATE
    }
    // Changed to fit into a single storage slot so the decimals needs to be recached
    struct Asset {
        // Note: OETHVaultCore doesn't use `isSupported` when minting,
        // redeeming or checking balance of assets.
        bool isSupported;
        UnitConversion unitConversion;
        uint8 decimals;
        // Max allowed slippage from the Oracle price when swapping collateral assets in basis points.
        // For example 40 == 0.4% slippage
        uint16 allowedOracleSlippageBps;
    }

    /// @dev mapping of supported vault assets to their configuration
    // slither-disable-next-line uninitialized-state
    mapping(address => Asset) internal assets;
    /// @dev list of all assets supported by the vault.
    // slither-disable-next-line uninitialized-state
    address[] internal allAssets;

    // Strategies approved for use by the Vault
    struct Strategy {
        bool isSupported;
        uint256 _deprecated; // Deprecated storage slot
    }
    /// @dev mapping of strategy contracts to their configiration
    mapping(address => Strategy) internal strategies;
    /// @dev list of all vault strategies
    address[] internal allStrategies;

    /// @notice Address of the Oracle price provider contract
    // slither-disable-next-line uninitialized-state
    address public priceProvider;
    /// @notice pause rebasing if true
    bool public rebasePaused = false;
    /// @notice pause operations that change the OToken supply.
    /// eg mint, redeem, allocate, mint/burn for strategy
    bool public capitalPaused = true;
    /// @notice Redemption fee in basis points. eg 50 = 0.5%
    uint256 public redeemFeeBps;
    /// @notice Percentage of assets to keep in Vault to handle (most) withdrawals. 100% = 1e18.
    uint256 public vaultBuffer;
    /// @notice OToken mints over this amount automatically allocate funds. 18 decimals.
    uint256 public autoAllocateThreshold;
    /// @notice OToken mints over this amount automatically rebase. 18 decimals.
    uint256 public rebaseThreshold;

    /// @dev Address of the OToken token. eg OUSD or OETH.
    // slither-disable-next-line uninitialized-state
    OUSD internal oUSD;

    //keccak256("OUSD.vault.governor.admin.impl");
    bytes32 constant adminImplPosition =
        0xa2bd3d3cf188a41358c8b401076eb59066b09dec5775650c0de4c55187d17bd9;

    // Address of the contract responsible for post rebase syncs with AMMs
    address private _deprecated_rebaseHooksAddr = address(0);

    // Deprecated: Address of Uniswap
    // slither-disable-next-line constable-states
    address private _deprecated_uniswapAddr = address(0);

    /// @notice Address of the Strategist
    address public strategistAddr = address(0);

    /// @notice Mapping of asset address to the Strategy that they should automatically
    // be allocated to
    // slither-disable-next-line uninitialized-state
    mapping(address => address) public assetDefaultStrategies;

    /// @notice Max difference between total supply and total value of assets. 18 decimals.
    // slither-disable-next-line uninitialized-state
    uint256 public maxSupplyDiff;

    /// @notice Trustee contract that can collect a percentage of yield
    address public trusteeAddress;

    /// @notice Amount of yield collected in basis points. eg 2000 = 20%
    uint256 public trusteeFeeBps;

    /// @dev Deprecated: Tokens that should be swapped for stablecoins
    address[] private _deprecated_swapTokens;

    uint256 constant MINT_MINIMUM_UNIT_PRICE = 0.998e18;

    /// @notice Metapool strategy that is allowed to mint/burn OTokens without changing collateral
    address public ousdMetaStrategy = address(0);

    /// @notice How much OTokens are currently minted by the strategy
    int256 public netOusdMintedForStrategy = 0;

    /// @notice How much net total OTokens are allowed to be minted by all strategies
    uint256 public netOusdMintForStrategyThreshold = 0;

    uint256 constant MIN_UNIT_PRICE_DRIFT = 0.7e18;
    uint256 constant MAX_UNIT_PRICE_DRIFT = 1.3e18;

    /// @notice Collateral swap configuration.
    /// @dev is packed into a single storage slot to save gas.
    struct SwapConfig {
        // Contract that swaps the vault's collateral assets
        address swapper;
        // Max allowed percentage the total value can drop below the total supply in basis points.
        // For example 100 == 1%
        uint16 allowedUndervalueBps;
    }
    SwapConfig internal swapConfig = SwapConfig(address(0), 0);

    // For future use
    uint256[50] private __gap;

    /**
     * @notice set the implementation for the admin, this needs to be in a base class else we cannot set it
     * @param newImpl address of the implementation
     */
    function setAdminImpl(address newImpl) external onlyGovernor {
        require(
            Address.isContract(newImpl),
            "new implementation is not a contract"
        );
        bytes32 position = adminImplPosition;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            sstore(position, newImpl)
        }
    }
}

{
  "compilationTarget": {
    "contracts/strategies/LidoWithdrawalStrategy.sol": "LidoWithdrawalStrategy"
  },
  "evmVersion": "london",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs",
    "useLiteralContent": true
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}