Sky Savings Rate DAI Lender

// SPDX-License-Identifier: GPL-3.0
pragma solidity 0.8.18;

// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/ERC20.sol)

// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

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

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

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

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

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

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

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

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

// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

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

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

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

// OpenZeppelin Contracts (last updated v4.9.4) (utils/Context.sol)

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

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

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * The default value of {decimals} is 18. To change this, you should override
 * this function so it returns a different value.
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

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

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

    /**
     * @dev 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. This is the default value returned by this function, unless
     * it's overridden.
     *
     * 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 virtual override returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address from, address to, uint256 amount) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(address from, address to, uint256 amount) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
            // decrementing then incrementing.
            _balances[to] += amount;
        }

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, 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:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        unchecked {
            // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
            _balances[account] += amount;
        }
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), 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 virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
            // Overflow not possible: amount <= accountBalance <= totalSupply.
            _totalSupply -= amount;
        }

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(address owner, address spender, uint256 amount) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(address from, address to, uint256 amount) internal virtual {}
}

// TokenizedStrategy interface used for internal view delegateCalls.

// OpenZeppelin Contracts (last updated v4.9.0) (interfaces/IERC4626.sol)

/**
 * @dev Interface of the ERC4626 "Tokenized Vault Standard", as defined in
 * https://eips.ethereum.org/EIPS/eip-4626[ERC-4626].
 *
 * _Available since v4.7._
 */
interface IERC4626 is IERC20, IERC20Metadata {
    event Deposit(address indexed sender, address indexed owner, uint256 assets, uint256 shares);

    event Withdraw(
        address indexed sender,
        address indexed receiver,
        address indexed owner,
        uint256 assets,
        uint256 shares
    );

    /**
     * @dev Returns the address of the underlying token used for the Vault for accounting, depositing, and withdrawing.
     *
     * - MUST be an ERC-20 token contract.
     * - MUST NOT revert.
     */
    function asset() external view returns (address assetTokenAddress);

    /**
     * @dev Returns the total amount of the underlying asset that is “managed” by Vault.
     *
     * - SHOULD include any compounding that occurs from yield.
     * - MUST be inclusive of any fees that are charged against assets in the Vault.
     * - MUST NOT revert.
     */
    function totalAssets() external view returns (uint256 totalManagedAssets);

    /**
     * @dev Returns the amount of shares that the Vault would exchange for the amount of assets provided, in an ideal
     * scenario where all the conditions are met.
     *
     * - MUST NOT be inclusive of any fees that are charged against assets in the Vault.
     * - MUST NOT show any variations depending on the caller.
     * - MUST NOT reflect slippage or other on-chain conditions, when performing the actual exchange.
     * - MUST NOT revert.
     *
     * NOTE: This calculation MAY NOT reflect the “per-user” price-per-share, and instead should reflect the
     * “average-user’s” price-per-share, meaning what the average user should expect to see when exchanging to and
     * from.
     */
    function convertToShares(uint256 assets) external view returns (uint256 shares);

    /**
     * @dev Returns the amount of assets that the Vault would exchange for the amount of shares provided, in an ideal
     * scenario where all the conditions are met.
     *
     * - MUST NOT be inclusive of any fees that are charged against assets in the Vault.
     * - MUST NOT show any variations depending on the caller.
     * - MUST NOT reflect slippage or other on-chain conditions, when performing the actual exchange.
     * - MUST NOT revert.
     *
     * NOTE: This calculation MAY NOT reflect the “per-user” price-per-share, and instead should reflect the
     * “average-user’s” price-per-share, meaning what the average user should expect to see when exchanging to and
     * from.
     */
    function convertToAssets(uint256 shares) external view returns (uint256 assets);

    /**
     * @dev Returns the maximum amount of the underlying asset that can be deposited into the Vault for the receiver,
     * through a deposit call.
     *
     * - MUST return a limited value if receiver is subject to some deposit limit.
     * - MUST return 2 ** 256 - 1 if there is no limit on the maximum amount of assets that may be deposited.
     * - MUST NOT revert.
     */
    function maxDeposit(address receiver) external view returns (uint256 maxAssets);

    /**
     * @dev Allows an on-chain or off-chain user to simulate the effects of their deposit at the current block, given
     * current on-chain conditions.
     *
     * - MUST return as close to and no more than the exact amount of Vault shares that would be minted in a deposit
     *   call in the same transaction. I.e. deposit should return the same or more shares as previewDeposit if called
     *   in the same transaction.
     * - MUST NOT account for deposit limits like those returned from maxDeposit and should always act as though the
     *   deposit would be accepted, regardless if the user has enough tokens approved, etc.
     * - MUST be inclusive of deposit fees. Integrators should be aware of the existence of deposit fees.
     * - MUST NOT revert.
     *
     * NOTE: any unfavorable discrepancy between convertToShares and previewDeposit SHOULD be considered slippage in
     * share price or some other type of condition, meaning the depositor will lose assets by depositing.
     */
    function previewDeposit(uint256 assets) external view returns (uint256 shares);

    /**
     * @dev Mints shares Vault shares to receiver by depositing exactly amount of underlying tokens.
     *
     * - MUST emit the Deposit event.
     * - MAY support an additional flow in which the underlying tokens are owned by the Vault contract before the
     *   deposit execution, and are accounted for during deposit.
     * - MUST revert if all of assets cannot be deposited (due to deposit limit being reached, slippage, the user not
     *   approving enough underlying tokens to the Vault contract, etc).
     *
     * NOTE: most implementations will require pre-approval of the Vault with the Vault’s underlying asset token.
     */
    function deposit(uint256 assets, address receiver) external returns (uint256 shares);

    /**
     * @dev Returns the maximum amount of the Vault shares that can be minted for the receiver, through a mint call.
     * - MUST return a limited value if receiver is subject to some mint limit.
     * - MUST return 2 ** 256 - 1 if there is no limit on the maximum amount of shares that may be minted.
     * - MUST NOT revert.
     */
    function maxMint(address receiver) external view returns (uint256 maxShares);

    /**
     * @dev Allows an on-chain or off-chain user to simulate the effects of their mint at the current block, given
     * current on-chain conditions.
     *
     * - MUST return as close to and no fewer than the exact amount of assets that would be deposited in a mint call
     *   in the same transaction. I.e. mint should return the same or fewer assets as previewMint if called in the
     *   same transaction.
     * - MUST NOT account for mint limits like those returned from maxMint and should always act as though the mint
     *   would be accepted, regardless if the user has enough tokens approved, etc.
     * - MUST be inclusive of deposit fees. Integrators should be aware of the existence of deposit fees.
     * - MUST NOT revert.
     *
     * NOTE: any unfavorable discrepancy between convertToAssets and previewMint SHOULD be considered slippage in
     * share price or some other type of condition, meaning the depositor will lose assets by minting.
     */
    function previewMint(uint256 shares) external view returns (uint256 assets);

    /**
     * @dev Mints exactly shares Vault shares to receiver by depositing amount of underlying tokens.
     *
     * - MUST emit the Deposit event.
     * - MAY support an additional flow in which the underlying tokens are owned by the Vault contract before the mint
     *   execution, and are accounted for during mint.
     * - MUST revert if all of shares cannot be minted (due to deposit limit being reached, slippage, the user not
     *   approving enough underlying tokens to the Vault contract, etc).
     *
     * NOTE: most implementations will require pre-approval of the Vault with the Vault’s underlying asset token.
     */
    function mint(uint256 shares, address receiver) external returns (uint256 assets);

    /**
     * @dev Returns the maximum amount of the underlying asset that can be withdrawn from the owner balance in the
     * Vault, through a withdraw call.
     *
     * - MUST return a limited value if owner is subject to some withdrawal limit or timelock.
     * - MUST NOT revert.
     */
    function maxWithdraw(address owner) external view returns (uint256 maxAssets);

    /**
     * @dev Allows an on-chain or off-chain user to simulate the effects of their withdrawal at the current block,
     * given current on-chain conditions.
     *
     * - MUST return as close to and no fewer than the exact amount of Vault shares that would be burned in a withdraw
     *   call in the same transaction. I.e. withdraw should return the same or fewer shares as previewWithdraw if
     *   called
     *   in the same transaction.
     * - MUST NOT account for withdrawal limits like those returned from maxWithdraw and should always act as though
     *   the withdrawal would be accepted, regardless if the user has enough shares, etc.
     * - MUST be inclusive of withdrawal fees. Integrators should be aware of the existence of withdrawal fees.
     * - MUST NOT revert.
     *
     * NOTE: any unfavorable discrepancy between convertToShares and previewWithdraw SHOULD be considered slippage in
     * share price or some other type of condition, meaning the depositor will lose assets by depositing.
     */
    function previewWithdraw(uint256 assets) external view returns (uint256 shares);

    /**
     * @dev Burns shares from owner and sends exactly assets of underlying tokens to receiver.
     *
     * - MUST emit the Withdraw event.
     * - MAY support an additional flow in which the underlying tokens are owned by the Vault contract before the
     *   withdraw execution, and are accounted for during withdraw.
     * - MUST revert if all of assets cannot be withdrawn (due to withdrawal limit being reached, slippage, the owner
     *   not having enough shares, etc).
     *
     * Note that some implementations will require pre-requesting to the Vault before a withdrawal may be performed.
     * Those methods should be performed separately.
     */
    function withdraw(uint256 assets, address receiver, address owner) external returns (uint256 shares);

    /**
     * @dev Returns the maximum amount of Vault shares that can be redeemed from the owner balance in the Vault,
     * through a redeem call.
     *
     * - MUST return a limited value if owner is subject to some withdrawal limit or timelock.
     * - MUST return balanceOf(owner) if owner is not subject to any withdrawal limit or timelock.
     * - MUST NOT revert.
     */
    function maxRedeem(address owner) external view returns (uint256 maxShares);

    /**
     * @dev Allows an on-chain or off-chain user to simulate the effects of their redeemption at the current block,
     * given current on-chain conditions.
     *
     * - MUST return as close to and no more than the exact amount of assets that would be withdrawn in a redeem call
     *   in the same transaction. I.e. redeem should return the same or more assets as previewRedeem if called in the
     *   same transaction.
     * - MUST NOT account for redemption limits like those returned from maxRedeem and should always act as though the
     *   redemption would be accepted, regardless if the user has enough shares, etc.
     * - MUST be inclusive of withdrawal fees. Integrators should be aware of the existence of withdrawal fees.
     * - MUST NOT revert.
     *
     * NOTE: any unfavorable discrepancy between convertToAssets and previewRedeem SHOULD be considered slippage in
     * share price or some other type of condition, meaning the depositor will lose assets by redeeming.
     */
    function previewRedeem(uint256 shares) external view returns (uint256 assets);

    /**
     * @dev Burns exactly shares from owner and sends assets of underlying tokens to receiver.
     *
     * - MUST emit the Withdraw event.
     * - MAY support an additional flow in which the underlying tokens are owned by the Vault contract before the
     *   redeem execution, and are accounted for during redeem.
     * - MUST revert if all of shares cannot be redeemed (due to withdrawal limit being reached, slippage, the owner
     *   not having enough shares, etc).
     *
     * NOTE: some implementations will require pre-requesting to the Vault before a withdrawal may be performed.
     * Those methods should be performed separately.
     */
    function redeem(uint256 shares, address receiver, address owner) external returns (uint256 assets);
}

// OpenZeppelin Contracts (last updated v4.9.4) (token/ERC20/extensions/IERC20Permit.sol)

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 *
 * ==== Security Considerations
 *
 * There are two important considerations concerning the use of `permit`. The first is that a valid permit signature
 * expresses an allowance, and it should not be assumed to convey additional meaning. In particular, it should not be
 * considered as an intention to spend the allowance in any specific way. The second is that because permits have
 * built-in replay protection and can be submitted by anyone, they can be frontrun. A protocol that uses permits should
 * take this into consideration and allow a `permit` call to fail. Combining these two aspects, a pattern that may be
 * generally recommended is:
 *
 * ```solidity
 * function doThingWithPermit(..., uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public {
 *     try token.permit(msg.sender, address(this), value, deadline, v, r, s) {} catch {}
 *     doThing(..., value);
 * }
 *
 * function doThing(..., uint256 value) public {
 *     token.safeTransferFrom(msg.sender, address(this), value);
 *     ...
 * }
 * ```
 *
 * Observe that: 1) `msg.sender` is used as the owner, leaving no ambiguity as to the signer intent, and 2) the use of
 * `try/catch` allows the permit to fail and makes the code tolerant to frontrunning. (See also
 * {SafeERC20-safeTransferFrom}).
 *
 * Additionally, note that smart contract wallets (such as Argent or Safe) are not able to produce permit signatures, so
 * contracts should have entry points that don't rely on permit.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     *
     * CAUTION: See Security Considerations above.
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

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

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

// Interface that implements the 4626 standard and the implementation functions
interface ITokenizedStrategy is IERC4626, IERC20Permit {
    /*//////////////////////////////////////////////////////////////
                                 EVENTS
    //////////////////////////////////////////////////////////////*/

    event StrategyShutdown();

    event NewTokenizedStrategy(
        address indexed strategy,
        address indexed asset,
        string apiVersion
    );

    event Reported(
        uint256 profit,
        uint256 loss,
        uint256 protocolFees,
        uint256 performanceFees
    );

    event UpdatePerformanceFeeRecipient(
        address indexed newPerformanceFeeRecipient
    );

    event UpdateKeeper(address indexed newKeeper);

    event UpdatePerformanceFee(uint16 newPerformanceFee);

    event UpdateManagement(address indexed newManagement);

    event UpdateEmergencyAdmin(address indexed newEmergencyAdmin);

    event UpdateProfitMaxUnlockTime(uint256 newProfitMaxUnlockTime);

    event UpdatePendingManagement(address indexed newPendingManagement);

    /*//////////////////////////////////////////////////////////////
                           INITIALIZATION
    //////////////////////////////////////////////////////////////*/

    function initialize(
        address _asset,
        string memory _name,
        address _management,
        address _performanceFeeRecipient,
        address _keeper
    ) external;

    /*//////////////////////////////////////////////////////////////
                    NON-STANDARD 4626 OPTIONS
    //////////////////////////////////////////////////////////////*/

    function withdraw(
        uint256 assets,
        address receiver,
        address owner,
        uint256 maxLoss
    ) external returns (uint256);

    function redeem(
        uint256 shares,
        address receiver,
        address owner,
        uint256 maxLoss
    ) external returns (uint256);

    function maxWithdraw(
        address owner,
        uint256 /*maxLoss*/
    ) external view returns (uint256);

    function maxRedeem(
        address owner,
        uint256 /*maxLoss*/
    ) external view returns (uint256);

    /*//////////////////////////////////////////////////////////////
                        MODIFIER HELPERS
    //////////////////////////////////////////////////////////////*/

    function requireManagement(address _sender) external view;

    function requireKeeperOrManagement(address _sender) external view;

    function requireEmergencyAuthorized(address _sender) external view;

    /*//////////////////////////////////////////////////////////////
                        KEEPERS FUNCTIONS
    //////////////////////////////////////////////////////////////*/

    function tend() external;

    function report() external returns (uint256 _profit, uint256 _loss);

    /*//////////////////////////////////////////////////////////////
                        CONSTANTS
    //////////////////////////////////////////////////////////////*/

    function MAX_FEE() external view returns (uint16);

    function FACTORY() external view returns (address);

    /*//////////////////////////////////////////////////////////////
                            GETTERS
    //////////////////////////////////////////////////////////////*/

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

    function pricePerShare() external view returns (uint256);

    function management() external view returns (address);

    function pendingManagement() external view returns (address);

    function keeper() external view returns (address);

    function emergencyAdmin() external view returns (address);

    function performanceFee() external view returns (uint16);

    function performanceFeeRecipient() external view returns (address);

    function fullProfitUnlockDate() external view returns (uint256);

    function profitUnlockingRate() external view returns (uint256);

    function profitMaxUnlockTime() external view returns (uint256);

    function lastReport() external view returns (uint256);

    function isShutdown() external view returns (bool);

    function unlockedShares() external view returns (uint256);

    /*//////////////////////////////////////////////////////////////
                            SETTERS
    //////////////////////////////////////////////////////////////*/

    function setPendingManagement(address) external;

    function acceptManagement() external;

    function setKeeper(address _keeper) external;

    function setEmergencyAdmin(address _emergencyAdmin) external;

    function setPerformanceFee(uint16 _performanceFee) external;

    function setPerformanceFeeRecipient(
        address _performanceFeeRecipient
    ) external;

    function setProfitMaxUnlockTime(uint256 _profitMaxUnlockTime) external;

    function setName(string calldata _newName) external;

    function shutdownStrategy() external;

    function emergencyWithdraw(uint256 _amount) external;
}

/**
 * @title YearnV3 Base Strategy
 * @author yearn.finance
 * @notice
 *  BaseStrategy implements all of the required functionality to
 *  seamlessly integrate with the `TokenizedStrategy` implementation contract
 *  allowing anyone to easily build a fully permissionless ERC-4626 compliant
 *  Vault by inheriting this contract and overriding three simple functions.

 *  It utilizes an immutable proxy pattern that allows the BaseStrategy
 *  to remain simple and small. All standard logic is held within the
 *  `TokenizedStrategy` and is reused over any n strategies all using the
 *  `fallback` function to delegatecall the implementation so that strategists
 *  can only be concerned with writing their strategy specific code.
 *
 *  This contract should be inherited and the three main abstract methods
 *  `_deployFunds`, `_freeFunds` and `_harvestAndReport` implemented to adapt
 *  the Strategy to the particular needs it has to generate yield. There are
 *  other optional methods that can be implemented to further customize
 *  the strategy if desired.
 *
 *  All default storage for the strategy is controlled and updated by the
 *  `TokenizedStrategy`. The implementation holds a storage struct that
 *  contains all needed global variables in a manual storage slot. This
 *  means strategists can feel free to implement their own custom storage
 *  variables as they need with no concern of collisions. All global variables
 *  can be viewed within the Strategy by a simple call using the
 *  `TokenizedStrategy` variable. IE: TokenizedStrategy.globalVariable();.
 */
abstract contract BaseStrategy {
    /*//////////////////////////////////////////////////////////////
                            MODIFIERS
    //////////////////////////////////////////////////////////////*/
    /**
     * @dev Used on TokenizedStrategy callback functions to make sure it is post
     * a delegateCall from this address to the TokenizedStrategy.
     */
    modifier onlySelf() {
        _onlySelf();
        _;
    }

    /**
     * @dev Use to assure that the call is coming from the strategies management.
     */
    modifier onlyManagement() {
        TokenizedStrategy.requireManagement(msg.sender);
        _;
    }

    /**
     * @dev Use to assure that the call is coming from either the strategies
     * management or the keeper.
     */
    modifier onlyKeepers() {
        TokenizedStrategy.requireKeeperOrManagement(msg.sender);
        _;
    }

    /**
     * @dev Use to assure that the call is coming from either the strategies
     * management or the emergency admin.
     */
    modifier onlyEmergencyAuthorized() {
        TokenizedStrategy.requireEmergencyAuthorized(msg.sender);
        _;
    }

    /**
     * @dev Require that the msg.sender is this address.
     */
    function _onlySelf() internal view {
        require(msg.sender == address(this), "!self");
    }

    /*//////////////////////////////////////////////////////////////
                            CONSTANTS
    //////////////////////////////////////////////////////////////*/

    /**
     * @dev This is the address of the TokenizedStrategy implementation
     * contract that will be used by all strategies to handle the
     * accounting, logic, storage etc.
     *
     * Any external calls to the that don't hit one of the functions
     * defined in this base or the strategy will end up being forwarded
     * through the fallback function, which will delegateCall this address.
     *
     * This address should be the same for every strategy, never be adjusted
     * and always be checked before any integration with the Strategy.
     */
    address public constant tokenizedStrategyAddress =
        0x254A93feff3BEeF9cA004E913bB5443754e8aB19;

    /*//////////////////////////////////////////////////////////////
                            IMMUTABLES
    //////////////////////////////////////////////////////////////*/

    /**
     * @dev Underlying asset the Strategy is earning yield on.
     * Stored here for cheap retrievals within the strategy.
     */
    ERC20 internal immutable asset;

    /**
     * @dev This variable is set to address(this) during initialization of each strategy.
     *
     * This can be used to retrieve storage data within the strategy
     * contract as if it were a linked library.
     *
     *       i.e. uint256 totalAssets = TokenizedStrategy.totalAssets()
     *
     * Using address(this) will mean any calls using this variable will lead
     * to a call to itself. Which will hit the fallback function and
     * delegateCall that to the actual TokenizedStrategy.
     */
    ITokenizedStrategy internal immutable TokenizedStrategy;

    /**
     * @notice Used to initialize the strategy on deployment.
     *
     * This will set the `TokenizedStrategy` variable for easy
     * internal view calls to the implementation. As well as
     * initializing the default storage variables based on the
     * parameters and using the deployer for the permissioned roles.
     *
     * @param _asset Address of the underlying asset.
     * @param _name Name the strategy will use.
     */
    constructor(address _asset, string memory _name) {
        asset = ERC20(_asset);

        // Set instance of the implementation for internal use.
        TokenizedStrategy = ITokenizedStrategy(address(this));

        // Initialize the strategy's storage variables.
        _delegateCall(
            abi.encodeCall(
                ITokenizedStrategy.initialize,
                (_asset, _name, msg.sender, msg.sender, msg.sender)
            )
        );

        // Store the tokenizedStrategyAddress at the standard implementation
        // address storage slot so etherscan picks up the interface. This gets
        // stored on initialization and never updated.
        assembly {
            sstore(
                // keccak256('eip1967.proxy.implementation' - 1)
                0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc,
                tokenizedStrategyAddress
            )
        }
    }

    /*//////////////////////////////////////////////////////////////
                NEEDED TO BE OVERRIDDEN BY STRATEGIST
    //////////////////////////////////////////////////////////////*/

    /**
     * @dev Can deploy up to '_amount' of 'asset' in the yield source.
     *
     * This function is called at the end of a {deposit} or {mint}
     * call. Meaning that unless a whitelist is implemented it will
     * be entirely permissionless and thus can be sandwiched or otherwise
     * manipulated.
     *
     * @param _amount The amount of 'asset' that the strategy can attempt
     * to deposit in the yield source.
     */
    function _deployFunds(uint256 _amount) internal virtual;

    /**
     * @dev Should attempt to free the '_amount' of 'asset'.
     *
     * NOTE: The amount of 'asset' that is already loose has already
     * been accounted for.
     *
     * This function is called during {withdraw} and {redeem} calls.
     * Meaning that unless a whitelist is implemented it will be
     * entirely permissionless and thus can be sandwiched or otherwise
     * manipulated.
     *
     * Should not rely on asset.balanceOf(address(this)) calls other than
     * for diff accounting purposes.
     *
     * Any difference between `_amount` and what is actually freed will be
     * counted as a loss and passed on to the withdrawer. This means
     * care should be taken in times of illiquidity. It may be better to revert
     * if withdraws are simply illiquid so not to realize incorrect losses.
     *
     * @param _amount, The amount of 'asset' to be freed.
     */
    function _freeFunds(uint256 _amount) internal virtual;

    /**
     * @dev Internal function to harvest all rewards, redeploy any idle
     * funds and return an accurate accounting of all funds currently
     * held by the Strategy.
     *
     * This should do any needed harvesting, rewards selling, accrual,
     * redepositing etc. to get the most accurate view of current assets.
     *
     * NOTE: All applicable assets including loose assets should be
     * accounted for in this function.
     *
     * Care should be taken when relying on oracles or swap values rather
     * than actual amounts as all Strategy profit/loss accounting will
     * be done based on this returned value.
     *
     * This can still be called post a shutdown, a strategist can check
     * `TokenizedStrategy.isShutdown()` to decide if funds should be
     * redeployed or simply realize any profits/losses.
     *
     * @return _totalAssets A trusted and accurate account for the total
     * amount of 'asset' the strategy currently holds including idle funds.
     */
    function _harvestAndReport()
        internal
        virtual
        returns (uint256 _totalAssets);

    /*//////////////////////////////////////////////////////////////
                    OPTIONAL TO OVERRIDE BY STRATEGIST
    //////////////////////////////////////////////////////////////*/

    /**
     * @dev Optional function for strategist to override that can
     *  be called in between reports.
     *
     * If '_tend' is used tendTrigger() will also need to be overridden.
     *
     * This call can only be called by a permissioned role so may be
     * through protected relays.
     *
     * This can be used to harvest and compound rewards, deposit idle funds,
     * perform needed position maintenance or anything else that doesn't need
     * a full report for.
     *
     *   EX: A strategy that can not deposit funds without getting
     *       sandwiched can use the tend when a certain threshold
     *       of idle to totalAssets has been reached.
     *
     * This will have no effect on PPS of the strategy till report() is called.
     *
     * @param _totalIdle The current amount of idle funds that are available to deploy.
     */
    function _tend(uint256 _totalIdle) internal virtual {}

    /**
     * @dev Optional trigger to override if tend() will be used by the strategy.
     * This must be implemented if the strategy hopes to invoke _tend().
     *
     * @return . Should return true if tend() should be called by keeper or false if not.
     */
    function _tendTrigger() internal view virtual returns (bool) {
        return false;
    }

    /**
     * @notice Returns if tend() should be called by a keeper.
     *
     * @return . Should return true if tend() should be called by keeper or false if not.
     * @return . Calldata for the tend call.
     */
    function tendTrigger() external view virtual returns (bool, bytes memory) {
        return (
            // Return the status of the tend trigger.
            _tendTrigger(),
            // And the needed calldata either way.
            abi.encodeWithSelector(ITokenizedStrategy.tend.selector)
        );
    }

    /**
     * @notice Gets the max amount of `asset` that an address can deposit.
     * @dev Defaults to an unlimited amount for any address. But can
     * be overridden by strategists.
     *
     * This function will be called before any deposit or mints to enforce
     * any limits desired by the strategist. This can be used for either a
     * traditional deposit limit or for implementing a whitelist etc.
     *
     *   EX:
     *      if(isAllowed[_owner]) return super.availableDepositLimit(_owner);
     *
     * This does not need to take into account any conversion rates
     * from shares to assets. But should know that any non max uint256
     * amounts may be converted to shares. So it is recommended to keep
     * custom amounts low enough as not to cause overflow when multiplied
     * by `totalSupply`.
     *
     * @param . The address that is depositing into the strategy.
     * @return . The available amount the `_owner` can deposit in terms of `asset`
     */
    function availableDepositLimit(
        address /*_owner*/
    ) public view virtual returns (uint256) {
        return type(uint256).max;
    }

    /**
     * @notice Gets the max amount of `asset` that can be withdrawn.
     * @dev Defaults to an unlimited amount for any address. But can
     * be overridden by strategists.
     *
     * This function will be called before any withdraw or redeem to enforce
     * any limits desired by the strategist. This can be used for illiquid
     * or sandwichable strategies. It should never be lower than `totalIdle`.
     *
     *   EX:
     *       return TokenIzedStrategy.totalIdle();
     *
     * This does not need to take into account the `_owner`'s share balance
     * or conversion rates from shares to assets.
     *
     * @param . The address that is withdrawing from the strategy.
     * @return . The available amount that can be withdrawn in terms of `asset`
     */
    function availableWithdrawLimit(
        address /*_owner*/
    ) public view virtual returns (uint256) {
        return type(uint256).max;
    }

    /**
     * @dev Optional function for a strategist to override that will
     * allow management to manually withdraw deployed funds from the
     * yield source if a strategy is shutdown.
     *
     * This should attempt to free `_amount`, noting that `_amount` may
     * be more than is currently deployed.
     *
     * NOTE: This will not realize any profits or losses. A separate
     * {report} will be needed in order to record any profit/loss. If
     * a report may need to be called after a shutdown it is important
     * to check if the strategy is shutdown during {_harvestAndReport}
     * so that it does not simply re-deploy all funds that had been freed.
     *
     * EX:
     *   if(freeAsset > 0 && !TokenizedStrategy.isShutdown()) {
     *       depositFunds...
     *    }
     *
     * @param _amount The amount of asset to attempt to free.
     */
    function _emergencyWithdraw(uint256 _amount) internal virtual {}

    /*//////////////////////////////////////////////////////////////
                        TokenizedStrategy HOOKS
    //////////////////////////////////////////////////////////////*/

    /**
     * @notice Can deploy up to '_amount' of 'asset' in yield source.
     * @dev Callback for the TokenizedStrategy to call during a {deposit}
     * or {mint} to tell the strategy it can deploy funds.
     *
     * Since this can only be called after a {deposit} or {mint}
     * delegateCall to the TokenizedStrategy msg.sender == address(this).
     *
     * Unless a whitelist is implemented this will be entirely permissionless
     * and thus can be sandwiched or otherwise manipulated.
     *
     * @param _amount The amount of 'asset' that the strategy can
     * attempt to deposit in the yield source.
     */
    function deployFunds(uint256 _amount) external virtual onlySelf {
        _deployFunds(_amount);
    }

    /**
     * @notice Should attempt to free the '_amount' of 'asset'.
     * @dev Callback for the TokenizedStrategy to call during a withdraw
     * or redeem to free the needed funds to service the withdraw.
     *
     * This can only be called after a 'withdraw' or 'redeem' delegateCall
     * to the TokenizedStrategy so msg.sender == address(this).
     *
     * @param _amount The amount of 'asset' that the strategy should attempt to free up.
     */
    function freeFunds(uint256 _amount) external virtual onlySelf {
        _freeFunds(_amount);
    }

    /**
     * @notice Returns the accurate amount of all funds currently
     * held by the Strategy.
     * @dev Callback for the TokenizedStrategy to call during a report to
     * get an accurate accounting of assets the strategy controls.
     *
     * This can only be called after a report() delegateCall to the
     * TokenizedStrategy so msg.sender == address(this).
     *
     * @return . A trusted and accurate account for the total amount
     * of 'asset' the strategy currently holds including idle funds.
     */
    function harvestAndReport() external virtual onlySelf returns (uint256) {
        return _harvestAndReport();
    }

    /**
     * @notice Will call the internal '_tend' when a keeper tends the strategy.
     * @dev Callback for the TokenizedStrategy to initiate a _tend call in the strategy.
     *
     * This can only be called after a tend() delegateCall to the TokenizedStrategy
     * so msg.sender == address(this).
     *
     * We name the function `tendThis` so that `tend` calls are forwarded to
     * the TokenizedStrategy.

     * @param _totalIdle The amount of current idle funds that can be
     * deployed during the tend
     */
    function tendThis(uint256 _totalIdle) external virtual onlySelf {
        _tend(_totalIdle);
    }

    /**
     * @notice Will call the internal '_emergencyWithdraw' function.
     * @dev Callback for the TokenizedStrategy during an emergency withdraw.
     *
     * This can only be called after a emergencyWithdraw() delegateCall to
     * the TokenizedStrategy so msg.sender == address(this).
     *
     * We name the function `shutdownWithdraw` so that `emergencyWithdraw`
     * calls are forwarded to the TokenizedStrategy.
     *
     * @param _amount The amount of asset to attempt to free.
     */
    function shutdownWithdraw(uint256 _amount) external virtual onlySelf {
        _emergencyWithdraw(_amount);
    }

    /**
     * @dev Function used to delegate call the TokenizedStrategy with
     * certain `_calldata` and return any return values.
     *
     * This is used to setup the initial storage of the strategy, and
     * can be used by strategist to forward any other call to the
     * TokenizedStrategy implementation.
     *
     * @param _calldata The abi encoded calldata to use in delegatecall.
     * @return . The return value if the call was successful in bytes.
     */
    function _delegateCall(
        bytes memory _calldata
    ) internal returns (bytes memory) {
        // Delegate call the tokenized strategy with provided calldata.
        (bool success, bytes memory result) = tokenizedStrategyAddress
            .delegatecall(_calldata);

        // If the call reverted. Return the error.
        if (!success) {
            assembly {
                let ptr := mload(0x40)
                let size := returndatasize()
                returndatacopy(ptr, 0, size)
                revert(ptr, size)
            }
        }

        // Return the result.
        return result;
    }

    /**
     * @dev Execute a function on the TokenizedStrategy and return any value.
     *
     * This fallback function will be executed when any of the standard functions
     * defined in the TokenizedStrategy are called since they wont be defined in
     * this contract.
     *
     * It will delegatecall the TokenizedStrategy implementation with the exact
     * calldata and return any relevant values.
     *
     */
    fallback() external {
        // load our target address
        address _tokenizedStrategyAddress = tokenizedStrategyAddress;
        // Execute external function using delegatecall and return any value.
        assembly {
            // Copy function selector and any arguments.
            calldatacopy(0, 0, calldatasize())
            // Execute function delegatecall.
            let result := delegatecall(
                gas(),
                _tokenizedStrategyAddress,
                0,
                calldatasize(),
                0,
                0
            )
            // Get any return value
            returndatacopy(0, 0, returndatasize())
            // Return any return value or error back to the caller
            switch result
            case 0 {
                revert(0, returndatasize())
            }
            default {
                return(0, returndatasize())
            }
        }
    }
}

/**
 *   @title Base Health Check
 *   @author Yearn.finance
 *   @notice This contract can be inherited by any Yearn
 *   V3 strategy wishing to implement a health check during
 *   the `report` function in order to prevent any unexpected
 *   behavior from being permanently recorded as well as the
 *   `checkHealth` modifier.
 *
 *   A strategist simply needs to inherit this contract. Set
 *   the limit ratios to the desired amounts and then
 *   override `_harvestAndReport()` just as they otherwise
 *  would. If the profit or loss that would be recorded is
 *   outside the acceptable bounds the tx will revert.
 *
 *   The healthcheck does not prevent a strategy from reporting
 *   losses, but rather can make sure manual intervention is
 *   needed before reporting an unexpected loss or profit.
 */
abstract contract BaseHealthCheck is BaseStrategy {
    // Can be used to determine if a healthcheck should be called.
    // Defaults to true;
    bool public doHealthCheck = true;

    uint256 internal constant MAX_BPS = 10_000;

    // Default profit limit to 100%.
    uint16 private _profitLimitRatio = uint16(MAX_BPS);

    // Defaults loss limit to 0.
    uint16 private _lossLimitRatio;

    constructor(
        address _asset,
        string memory _name
    ) BaseStrategy(_asset, _name) {}

    /**
     * @notice Returns the current profit limit ratio.
     * @dev Use a getter function to keep the variable private.
     * @return . The current profit limit ratio.
     */
    function profitLimitRatio() public view returns (uint256) {
        return _profitLimitRatio;
    }

    /**
     * @notice Returns the current loss limit ratio.
     * @dev Use a getter function to keep the variable private.
     * @return . The current loss limit ratio.
     */
    function lossLimitRatio() public view returns (uint256) {
        return _lossLimitRatio;
    }

    /**
     * @notice Set the `profitLimitRatio`.
     * @dev Denominated in basis points. I.E. 1_000 == 10%.
     * @param _newProfitLimitRatio The mew profit limit ratio.
     */
    function setProfitLimitRatio(
        uint256 _newProfitLimitRatio
    ) external onlyManagement {
        _setProfitLimitRatio(_newProfitLimitRatio);
    }

    /**
     * @dev Internally set the profit limit ratio. Denominated
     * in basis points. I.E. 1_000 == 10%.
     * @param _newProfitLimitRatio The mew profit limit ratio.
     */
    function _setProfitLimitRatio(uint256 _newProfitLimitRatio) internal {
        require(_newProfitLimitRatio > 0, "!zero profit");
        require(_newProfitLimitRatio <= type(uint16).max, "!too high");
        _profitLimitRatio = uint16(_newProfitLimitRatio);
    }

    /**
     * @notice Set the `lossLimitRatio`.
     * @dev Denominated in basis points. I.E. 1_000 == 10%.
     * @param _newLossLimitRatio The new loss limit ratio.
     */
    function setLossLimitRatio(
        uint256 _newLossLimitRatio
    ) external onlyManagement {
        _setLossLimitRatio(_newLossLimitRatio);
    }

    /**
     * @dev Internally set the loss limit ratio. Denominated
     * in basis points. I.E. 1_000 == 10%.
     * @param _newLossLimitRatio The new loss limit ratio.
     */
    function _setLossLimitRatio(uint256 _newLossLimitRatio) internal {
        require(_newLossLimitRatio < MAX_BPS, "!loss limit");
        _lossLimitRatio = uint16(_newLossLimitRatio);
    }

    /**
     * @notice Turns the healthcheck on and off.
     * @dev If turned off the next report will auto turn it back on.
     * @param _doHealthCheck Bool if healthCheck should be done.
     */
    function setDoHealthCheck(bool _doHealthCheck) public onlyManagement {
        doHealthCheck = _doHealthCheck;
    }

    /**
     * @notice OVerrides the default {harvestAndReport} to include a healthcheck.
     * @return _totalAssets New totalAssets post report.
     */
    function harvestAndReport()
        external
        override
        onlySelf
        returns (uint256 _totalAssets)
    {
        // Let the strategy report.
        _totalAssets = _harvestAndReport();

        // Run the healthcheck on the amount returned.
        _executeHealthCheck(_totalAssets);
    }

    /**
     * @dev To be called during a report to make sure the profit
     * or loss being recorded is within the acceptable bound.
     *
     * @param _newTotalAssets The amount that will be reported.
     */
    function _executeHealthCheck(uint256 _newTotalAssets) internal virtual {
        if (!doHealthCheck) {
            doHealthCheck = true;
            return;
        }

        // Get the current total assets from the implementation.
        uint256 currentTotalAssets = TokenizedStrategy.totalAssets();

        if (_newTotalAssets > currentTotalAssets) {
            require(
                ((_newTotalAssets - currentTotalAssets) <=
                    (currentTotalAssets * uint256(_profitLimitRatio)) /
                        MAX_BPS),
                "healthCheck"
            );
        } else if (currentTotalAssets > _newTotalAssets) {
            require(
                (currentTotalAssets - _newTotalAssets <=
                    ((currentTotalAssets * uint256(_lossLimitRatio)) /
                        MAX_BPS)),
                "healthCheck"
            );
        }
    }
}

// OpenZeppelin Contracts (last updated v4.9.3) (token/ERC20/utils/SafeERC20.sol)

// OpenZeppelin Contracts (last updated v4.9.0) (utils/Address.sol)

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

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.8.0/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

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

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

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

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

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

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

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

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

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

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

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

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

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

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

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

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

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

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

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

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

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

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

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

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

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

interface IPSM {
    function sellGem(address usr, uint256 gemAmt) external;
    function buyGem(address usr, uint256 gemAmt) external;
    function tin() external view returns(uint256);
    function tout() external view returns(uint256);
}

interface IExchange {
    function daiToUsds(address usr, uint256 wad) external;
    function usdsToDai(address usr, uint256 wad) external;
}

interface IVault {
    function asset() external view returns (address);
    function deposit(uint256 assets, address receiver) external;
    function withdraw(uint256 assets, address receiver, address owner) external;
    function withdraw(uint256 assets, address receiver, address owner, uint256 maxLoss) external;
    function redeem(uint256 shares, address receiver, address owner) external returns (uint256 assets);
    function redeem(uint256 shares, address receiver, address owner, uint256 maxLoss) external returns (uint256 assets);
    function convertToAssets(uint256 shares) external view returns (uint256);
    function convertToShares(uint256 assets) external view returns (uint256);
    function maxDeposit(address) external view returns (uint256);
    function maxRedeem(address) external view returns (uint256);
    function maxWithdraw(address) external view returns (uint256);
    function previewWithdraw(uint256) external view returns (uint256);
}

/// @title yearn-v3-USDS-Farmer-DAI
/// @author mil0x
/// @notice yearn v3 Strategy that trades DAI to USDS to farm 4626 vault.
contract USDSFarmerDAI is BaseHealthCheck {
    using SafeERC20 for ERC20;

    ///@notice The 4626 vault for USDS asset to farm.
    address public immutable vault;
    
    address private constant DAI = 0x6B175474E89094C44Da98b954EedeAC495271d0F;
    address private constant USDS = 0xdC035D45d973E3EC169d2276DDab16f1e407384F;
    address private constant DAI_USDS_EXCHANGER = 0x3225737a9Bbb6473CB4a45b7244ACa2BeFdB276A;
    uint256 private constant ASSET_DUST = 100;

    constructor(address _vault, string memory _name) BaseHealthCheck(DAI, _name) {
        require(IVault(_vault).asset() == USDS, "!asset");
        vault = _vault;

        //approvals:
        ERC20(DAI).forceApprove(DAI_USDS_EXCHANGER, type(uint).max); //approve the PSM
        ERC20(USDS).forceApprove(DAI_USDS_EXCHANGER, type(uint).max); //approve the PSM
        ERC20(USDS).forceApprove(vault, type(uint).max);
    }

    /*//////////////////////////////////////////////////////////////
                INTERNAL
    //////////////////////////////////////////////////////////////*/

    function availableDepositLimit(address /*_owner*/) public view virtual override returns (uint256) {
        return IVault(vault).maxDeposit(address(this));
    }

    function _deployFunds(uint256 _amount) internal override {
        IExchange(DAI_USDS_EXCHANGER).daiToUsds(address(this), _amount); //DAI --> USDS 1:1
        IVault(vault).deposit(_amount, address(this)); //USDS --> vault
    }

    function availableWithdrawLimit(address) public view virtual override returns (uint256) {
        return _balanceAsset() + _vaultsMaxWithdraw();
    }

    function _vaultsMaxWithdraw() internal view returns (uint256) {
        return IVault(vault).convertToAssets(IVault(vault).maxRedeem(address(this)));
    }

    function _freeFunds(uint256 _amount) internal override {
        _amount = IVault(vault).previewWithdraw(_amount);
        _amount = _min(_amount, _balanceVault());
        IExchange(DAI_USDS_EXCHANGER).usdsToDai(address(this), IVault(vault).redeem(_amount, address(this), address(this))); //vault --> USDS -- 1:1 --> DAI
    }

    function _harvestAndReport() internal override returns (uint256 _totalAssets) {
        uint256 balance = _balanceAsset();
        if (TokenizedStrategy.isShutdown()) {
            _totalAssets = balance + IVault(vault).convertToAssets(_balanceVault());
        } else {
            balance = _min(balance, availableDepositLimit(address(this)));
            if (balance > ASSET_DUST) {
                _deployFunds(balance);
            }
            _totalAssets = _balanceAsset() + IVault(vault).convertToAssets(_balanceVault());
        }
    }

    function _min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    function _balanceAsset() internal view returns (uint256) {
        return asset.balanceOf(address(this));
    }

    function _balanceUSDS() internal view returns (uint256) {
        return ERC20(USDS).balanceOf(address(this));
    }

    function _balanceVault() internal view returns (uint256) {
        return ERC20(vault).balanceOf(address(this));
    }

    /**
     * @notice Deploy any idle of USDS.
     */
    function deployIdle() external onlyManagement {
        IVault(vault).deposit(_balanceUSDS(), address(this)); //USDS --> vault
    }

    /*//////////////////////////////////////////////////////////////
                EMERGENCY
    //////////////////////////////////////////////////////////////*/

    /**
     * @notice Withdraw funds from the vault into the strategy in an emergency.
     * @param _amount the amount of asset to emergencyWithdraw into the strategy
     */
    function _emergencyWithdraw(uint256 _amount) internal override {
        _freeFunds(_min(_amount, _vaultsMaxWithdraw()));
    }
}

{
  "compilationTarget": {
    "USDSFarmerDAI.sol": "USDSFarmerDAI"
  },
  "evmVersion": "paris",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}