// SPDX-License-Identifier: UNLICENSED

pragma solidity ^0.8.9;

/**
 * @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);
}

/**
 * @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);
}

/**
 * @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;
    }
}

/**
 * @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].
 *
 * 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}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * 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 value {ERC20} uses, unless this function is
     * 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 {}
}

interface ILSDStorage {
    // Depoly status
    function getDeployedStatus() external view returns (bool);

    // Guardian
    function getGuardian() external view returns (address);

    function setGuardian(address _newAddress) external;

    function confirmGuardian() external;

    // Getters
    function getAddress(bytes32 _key) external view returns (address);

    function getUint(bytes32 _key) external view returns (uint256);

    function getString(bytes32 _key) external view returns (string memory);

    function getBytes(bytes32 _key) external view returns (bytes memory);

    function getBool(bytes32 _key) external view returns (bool);

    function getInt(bytes32 _key) external view returns (int256);

    function getBytes32(bytes32 _key) external view returns (bytes32);

    // Setters
    function setAddress(bytes32 _key, address _value) external;

    function setUint(bytes32 _key, uint256 _value) external;

    function setString(bytes32 _key, string calldata _value) external;

    function setBytes(bytes32 _key, bytes calldata _value) external;

    function setBool(bytes32 _key, bool _value) external;

    function setInt(bytes32 _key, int256 _value) external;

    function setBytes32(bytes32 _key, bytes32 _value) external;

    // Deleters
    function deleteAddress(bytes32 _key) external;

    function deleteUint(bytes32 _key) external;

    function deleteString(bytes32 _key) external;

    function deleteBytes(bytes32 _key) external;

    function deleteBool(bytes32 _key) external;

    function deleteInt(bytes32 _key) external;

    function deleteBytes32(bytes32 _key) external;

    // Arithmetic
    function addUint(bytes32 _key, uint256 _amount) external;

    function subUint(bytes32 _key, uint256 _amount) external;
}

/// @title Base settings / modifiers for each contract in LSD

abstract contract LSDBase {
    // Calculate using this as the base
    uint256 constant calcBase = 1 ether;

    // Version of the contract
    uint8 public version;

    // The main storage contact where primary persistant storage is maintained
    ILSDStorage lsdStorage;

    /*** Modifiers ***********************************************************/

    /**
     * @dev Throws if called by any sender that doesn't match a LSD network contract
     */
    modifier onlyLSDNetworkContract() {
        require(
            getBool(
                keccak256(abi.encodePacked("contract.exists", msg.sender))
            ),
            "Invalid contract"
        );
        _;
    }

    /**
     * @dev Throws if called by any sender that doesn't match one of the supplied contract
     */
    modifier onlyLSDContract(
        string memory _contractName,
        address _contractAddress
    ) {
        require(
            _contractAddress ==
                getAddress(
                    keccak256(
                        abi.encodePacked("contract.address", _contractName)
                    )
                ),
            "Invalid contract"
        );
        _;
    }

    /*** Methods **********************************************************************/

    /// @dev Set the main LSD storage address
    constructor(ILSDStorage _lsdStorageAddress) {
        // Update the contract address
        lsdStorage = ILSDStorage(_lsdStorageAddress);
    }

    /// @dev Get the address of a network contract by name
    function getContractAddress(string memory _contractName)
        internal
        view
        returns (address)
    {
        // Get the current contract address
        address contractAddress = getAddress(
            keccak256(abi.encodePacked("contract.address", _contractName))
        );
        // Check it
        require(contractAddress != address(0x0), "Contract not found");
        return contractAddress;
    }

    /// @dev Get the name of a network contract by address
    function getContractName(address _contractAddress)
        internal
        view
        returns (string memory)
    {
        // Get the contract name
        string memory contractName = getString(
            keccak256(abi.encodePacked("contract.name", _contractAddress))
        );
        // Check it
        require(bytes(contractName).length > 0, "Contract not found");
        // Return
        return contractName;
    }

    /// @dev Get revert error message from a .call method
    function getRevertMsg(bytes memory _returnData)
        internal
        pure
        returns (string memory)
    {
        // If the _res length is less than 68, then the transaction failed silently (without a revert message)
        if (_returnData.length < 68) return "Transaction reverted silently";
        assembly {
            // Slice the sighash
            _returnData := add(_returnData, 0x04)
        }
        return abi.decode(_returnData, (string)); // All that remains is the revert string
    }

    /*** LSD Storage Methods ********************************************************/

    // Note: Uused helpers have been removed to keep contract sizes down

    /// @dev Storage get methods
    function getAddress(bytes32 _key) internal view returns (address) {
        return lsdStorage.getAddress(_key);
    }

    function getUint(bytes32 _key) internal view returns (uint256) {
        return lsdStorage.getUint(_key);
    }

    function getString(bytes32 _key) internal view returns (string memory) {
        return lsdStorage.getString(_key);
    }

    function getBytes(bytes32 _key) internal view returns (bytes memory) {
        return lsdStorage.getBytes(_key);
    }

    function getBool(bytes32 _key) internal view returns (bool) {
        return lsdStorage.getBool(_key);
    }

    function getInt(bytes32 _key) internal view returns (int256) {
        return lsdStorage.getInt(_key);
    }

    function getBytes32(bytes32 _key) internal view returns (bytes32) {
        return lsdStorage.getBytes32(_key);
    }

    /// @dev Storage set methods
    function setAddress(bytes32 _key, address _value) internal {
        lsdStorage.setAddress(_key, _value);
    }

    function setUint(bytes32 _key, uint256 _value) internal {
        lsdStorage.setUint(_key, _value);
    }

    function setString(bytes32 _key, string memory _value) internal {
        lsdStorage.setString(_key, _value);
    }

    function setBytes(bytes32 _key, bytes memory _value) internal {
        lsdStorage.setBytes(_key, _value);
    }

    function setBool(bytes32 _key, bool _value) internal {
        lsdStorage.setBool(_key, _value);
    }

    function setInt(bytes32 _key, int256 _value) internal {
        lsdStorage.setInt(_key, _value);
    }

    function setBytes32(bytes32 _key, bytes32 _value) internal {
        lsdStorage.setBytes32(_key, _value);
    }

    /// @dev Storage delete methods
    function deleteAddress(bytes32 _key) internal {
        lsdStorage.deleteAddress(_key);
    }

    function deleteUint(bytes32 _key) internal {
        lsdStorage.deleteUint(_key);
    }

    function deleteString(bytes32 _key) internal {
        lsdStorage.deleteString(_key);
    }

    function deleteBytes(bytes32 _key) internal {
        lsdStorage.deleteBytes(_key);
    }

    function deleteBool(bytes32 _key) internal {
        lsdStorage.deleteBool(_key);
    }

    function deleteInt(bytes32 _key) internal {
        lsdStorage.deleteInt(_key);
    }

    function deleteBytes32(bytes32 _key) internal {
        lsdStorage.deleteBytes32(_key);
    }

    /// @dev Storage arithmetic methods
    function addUint(bytes32 _key, uint256 _amount) internal {
        lsdStorage.addUint(_key, _amount);
    }

    function subUint(bytes32 _key, uint256 _amount) internal {
        lsdStorage.subUint(_key, _amount);
    }
}

interface ILSDUpdateBalance {
    function getLastUpdateVitualETHBalanceTime()
        external
        view
        returns (uint256);

    function getVirtualETHBalance() external view returns (uint256);

    function addVirtualETHBalance(uint256 _amount) external;

    function subVirtualETHBalance(uint256 _amount) external;

    function updateVirtualETHBalance() external;

    function getTotalLSETHSupply() external view returns (uint256);

    function getTotalVELSDSupply() external view returns (uint256);

}

interface ILSDDepositPool {
    function deposit() external payable;

    function getCurrentProvider() external view returns (uint256);

    function withdrawEther(uint256 _amount, address _address) external;
}

interface ILSDOwner {
    function getApy() external view returns (uint256);

    function getStakeApr() external view returns (uint256);

    function getMultiplier() external view returns (uint256);

    function getLIDOApy() external view returns (uint256);

    function getRPApy() external view returns (uint256);

    function getSWISEApy() external view returns (uint256);

    function getProtocolFee() external view returns (uint256);

    function getMinimumDepositAmount() external view returns (uint256);

    function setApy(uint256 _apy) external;

    function setStakeApr(uint256 _stakeApr) external;

    function setMultiplier(uint256 _multiplier) external;

    function setRPApy(uint256 _rpApy) external;

    function setLIDOApy(uint256 _lidoApy) external;

    function setSWISEApy(uint256 _swiseApy) external;

    function setProtocolFee(uint256 _protocalFee) external;

    function setMinimumDepositAmount(uint256 _minimumDepositAmount) external;

    function upgrade(string memory _type, string memory _name, string memory _contractAbi, address _contractAddress) external;
}

interface ILSDTokenLSETH is IERC20 {
  function getEthValue(uint256 _lsethAmount) external view returns (uint256);
  function getLsethValue(uint256 _ethAmount) external view returns (uint256);
  function getExchangeRate() external view returns (uint256);
  function mint(uint256 _ethAmount, address _to) external;
  function burn(uint256 _lsethAmount) external;
}

interface ILSDTokenVELSD is IERC20 {
    function mint(address _address, uint256 _amount) external;

    function burn(address _address, uint256 _amount) external;
}

// lsETH is a tokenised stake in the LSD network
// lsETH is backed by ETH (subject to liquidity) at a variable exchange rate

contract LSDTokenLSETH is LSDBase, ERC20, ILSDTokenLSETH {
    // Events
    event EtherDeposited(address indexed from, uint256 amount, uint256 time);

    event TokensMinted(
        address indexed to,
        uint256 amount,
        uint256 ethAmount,
        uint256 time
    );
    event TokensBurned(
        address indexed from,
        uint256 amount,
        uint256 ethAmount,
        uint256 time
    );

    // Construct with our token details
    constructor(ILSDStorage _lsdStorageAddress)
        LSDBase(_lsdStorageAddress)
        ERC20("LSD ETH", "lsETH")
    {
        // Version
        version = 1;
    }

    // Receives an ETH deposit from generous individual
    receive() external payable {
        // Emit ether deposited event
        emit EtherDeposited(msg.sender, msg.value, block.timestamp);
    }

    // Calculate the amount of ETH backing an amount of lsETH
    function getEthValue(uint256 _lsethAmount)
        public
        view
        override
        returns (uint256)
    {
        // Get balances
        ILSDUpdateBalance lsdUpdateBalance = ILSDUpdateBalance(
            getContractAddress("lsdUpdateBalance")
        );
        uint256 lsethSupply = totalSupply();
        uint256 virtualETHBalance = lsdUpdateBalance.getVirtualETHBalance();
        // Use 1:1 ratio if no lsETH is minted
        if (lsethSupply == 0) {
            return _lsethAmount;
        }
        // Calculate and return
        return (_lsethAmount * virtualETHBalance) / lsethSupply;
    }

    // Calculate the amount of lsETH backed by an amount of ETH
    function getLsethValue(uint256 _ethAmount)
        public
        view
        override
        returns (uint256)
    {
        // Get balances
        ILSDUpdateBalance lsdUpdateBalance = ILSDUpdateBalance(
            getContractAddress("lsdUpdateBalance")
        );
        uint256 lsethSupply = lsdUpdateBalance.getTotalLSETHSupply();
        uint256 virtualETHBalance = lsdUpdateBalance.getVirtualETHBalance();

        // Use 1:1 ratio if no lsETH is minted
        if (lsethSupply == 0) {
            return _ethAmount;
        }
        // Check ETH balance
        require(
            virtualETHBalance > 0,
            "Cannot calculate lsETH token amount while total network balance is zero"
        );
        // Calculate and return
        return (_ethAmount * lsethSupply) / virtualETHBalance;
    }

    // Get the current ETH : lsETH exchange rate
    // Return the amount of ETH backing 1 lsETH
    function getExchangeRate() external view override returns (uint256) {
        return getEthValue(1 ether);
    }

    // Mint lsETH
    // Only accepts calls from the LSD contract
    function mint(uint256 _ethAmount, address _to)
        external
        override
        onlyLSDContract("lsdDepositPool", msg.sender)
    {
        // Get lsETH amount
        uint256 lsethAmount = getLsethValue(_ethAmount);
        // Check lsETH amount
        require(lsethAmount > 0, "Invalid token mint amount");
        // Update balance & supply
        _mint(_to, lsethAmount);

        ILSDUpdateBalance lsdUpdateBalance = ILSDUpdateBalance(
            getContractAddress("lsdUpdateBalance")
        );
        lsdUpdateBalance.addVirtualETHBalance(_ethAmount);
        // Emit tokens minted event
        emit TokensMinted(_to, lsethAmount, _ethAmount, block.timestamp);
    }

    // Burn lsETH for ETH
    function burn(uint256 _lsethAmount) external override {
        // Check lsETH amount
        require(_lsethAmount > 0, "Invalid token burn amount");
        require(
            balanceOf(msg.sender) >= _lsethAmount,
            "Insufficient lsETH balance"
        );

        // Get ETH amount
        uint256 ethAmount = getEthValue(_lsethAmount);
        // Get & Check ETH balance
        ILSDDepositPool lsdDepositPool = ILSDDepositPool(
            getContractAddress("lsdDepositPool")
        );

        // Update balance & supply
        _burn(msg.sender, _lsethAmount);
        // Withdraw ETH from deposit pool if required
        lsdDepositPool.withdrawEther(ethAmount, msg.sender);
        
        ILSDUpdateBalance lsdUpdateBalance = ILSDUpdateBalance(
            getContractAddress("lsdUpdateBalance")
        );
        lsdUpdateBalance.subVirtualETHBalance(ethAmount);
        // Emit token burned event
        emit TokensBurned(msg.sender, _lsethAmount, ethAmount, block.timestamp);
    }

    // This is called by the ERC20 contract before all transfer, mint, and burns
    function _beforeTokenTransfer(
        address from,
        address,
        uint256
    ) internal override {
        // Don't run check if this is a mint transaction
        if (from != address(0)) {
            // update the virtual ETH balance
            ILSDUpdateBalance lsdUpdateBalance = ILSDUpdateBalance(
                getContractAddress("lsdUpdateBalance")
            );
            lsdUpdateBalance.updateVirtualETHBalance();
        }
    }
}