// File: contracts/MarryStrgtVaultWrapper.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;

import {IStrgtEthVault} from "./interfaces/IStrgtEthVault.sol";
import {IMarryStrgtVault} from "./interfaces/IMarryStrgtVault.sol";
import {IStrgtRouter} from "./interfaces/IStrgtRouter.sol";
import {IStrgtPool} from "./interfaces/IStrgtPool.sol";

import {Owned} from "solmate/src/auth/Owned.sol";
import {ERC20} from "solmate/src/tokens/ERC20.sol";
import {SafeTransferLib} from "solmate/src/utils/SafeTransferLib.sol";
import {FixedPointMathLib} from "solmate/src/utils/FixedPointMathLib.sol";

/// @notice Allows to deposit and underlying token directly to vault
contract MarryStrgtVaultWrapper is Owned {
    using SafeTransferLib for ERC20;
    using FixedPointMathLib for uint256;

    /*//////////////////////////////////////////////////////////////
                                ADDRESSES
    //////////////////////////////////////////////////////////////*/

    /// @notice Address of the Strgt ETH Wrapped
    IStrgtEthVault public immutable SGETH;

    /// @notice Address of the Startgate Router
    IStrgtRouter public immutable strgtRouter;

    /*//////////////////////////////////////////////////////////////
                                 ERRORS
    //////////////////////////////////////////////////////////////*/

    error MarryStrgtVaultWrapper__InsufficientOut();

    /*//////////////////////////////////////////////////////////////
                               CONSTRUCTOR
    //////////////////////////////////////////////////////////////*/

    /// @notice Sets the SGETH, Strgt Router and Owner address of this wrapper
    /// @param _SGETH Address of the Strgt ETH wrapper
    /// @param _strgtRouter Address of the Strgt Router
    /// @param _owner Address of the owner of this vault wrapper
    constructor(
        address _SGETH,
        address _strgtRouter,
        address _owner
    ) Owned(_owner) {
        SGETH = IStrgtEthVault(_SGETH);
        strgtRouter = IStrgtRouter(_strgtRouter);
    }

    /*//////////////////////////////////////////////////////////////
                          Vault Deposit & Withdraw LOGIC
    //////////////////////////////////////////////////////////////*/

    /// @notice Allows you to deposit the underlying token directly to the vault
    /// @dev Make sure that you calculate the minOut from the before, the vault can
    /// send lesser share, than expected. If you need to deposit Strgt Pool tokens,
    /// use the vault directly.
    /// @param vault Address of the vault
    /// @param minOut The minimum vault share to be received
    /// @param assets Amount of assets to be deposited
    /// @param receiver Address of the vault shares receiver
    /// @return sharesVault Returns Share in the Vault
    /// @return sharesPool Returns Share in the Strgt Pool
    function depositUnderlyingToVault(
        IMarryStrgtVault vault,
        uint256 minOut,
        uint256 assets,
        address receiver
    ) external payable returns (uint256 sharesVault, uint256 sharesPool) {
        ERC20 underlyingAsset = ERC20(vault.underlyingAsset());
        ERC20 asset = ERC20(vault.asset());

        uint256 poolId = vault.poolId();

        if (address(underlyingAsset) == address(SGETH)) {
            SGETH.deposit{value: assets}();
        } else {
            underlyingAsset.safeTransferFrom(msg.sender, address(this), assets);
        }

        strgtRouter.addLiquidity(poolId, assets, address(this));
        sharesPool = asset.balanceOf(address(this));
        sharesVault = vault.deposit(sharesPool, receiver);

        if (sharesVault < minOut)
            revert MarryStrgtVaultWrapper__InsufficientOut();
    }

    /// @notice Allows you to withdraw the underlying token directly to the vault
    /// @dev Make sure that you calculate the minOut from the before, the vault can
    /// send lesser asset, than expected, due to insufficient liquidity at Strgt
    /// If you need to withdraw Strgt Pool tokens, use the vault directly
    /// @param vault Address of the vault
    /// @param minOut The minimum asssets to be received
    /// @param shares Amount of shares to be withdrawn
    /// @param receiver Address of the assets receiver
    /// @return assetsVault Returns Asssets in the Vault
    /// @return assetsPool Returns Assets in the Strgt Pool
    function withdrawUnderlyingFromVault(
        IMarryStrgtVault vault,
        uint256 minOut,
        uint256 shares,
        address receiver
    ) external returns (uint256 assetsVault, uint256 assetsPool) {
        ERC20 underlyingAsset = ERC20(vault.underlyingAsset());
        uint256 poolId = vault.poolId();

        assetsVault = vault.redeem(shares, address(this), msg.sender);

        strgtRouter.instantRedeemLocal(
            uint16(poolId),
            assetsVault,
            address(this)
        );

        if (address(underlyingAsset) == address(SGETH)) {
            assetsPool = address(this).balance;
            SafeTransferLib.safeTransferETH(receiver, assetsPool);
        } else {
            assetsPool = underlyingAsset.balanceOf(address(this));
            underlyingAsset.safeTransfer(receiver, assetsPool);
        }

        if (assetsPool < minOut)
            revert MarryStrgtVaultWrapper__InsufficientOut();
    }

    /*//////////////////////////////////////////////////////////////
                          ADMIN FUNCTIONS
    //////////////////////////////////////////////////////////////*/

    /// @notice Approves the wrapper to vault and the router
    /// @dev Only the owner of this wrapper can call this function
    /// @param vaults Addresses of the vaults to approve
    function approveToVault(address[] calldata vaults) external onlyOwner {
        for (uint256 i; i < vaults.length; i++) {
            ERC20(IMarryStrgtVault(vaults[i]).asset()).safeApprove(
                vaults[i],
                type(uint256).max
            );
            ERC20(IMarryStrgtVault(vaults[i]).underlyingAsset())
                .safeApprove(address(strgtRouter), type(uint256).max);
        }
    }

    receive() external payable {}
}

// File: contracts/interfaces/IMarryStrgtVault.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0;

interface IMarryStrgtVault {
    function deposit(uint256 assets, address receiver)
        external
        returns (uint256 shares);

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

    function underlyingAsset() external view returns (address);

    function asset() external view returns (address);

    function poolId() external view returns (uint256);
}

// File: contracts/interfaces/IStrgtRouter.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0;

interface IStrgtRouter {
    struct lzTxObj {
        uint256 dstGasForCall;
        uint256 dstNativeAmount;
        bytes dstNativeAddr;
    }

    function addLiquidity(
        uint256 _poolId,
        uint256 _amountLD,
        address _to
    ) external;

    function swap(
        uint16 _dstChainId,
        uint256 _srcPoolId,
        uint256 _dstPoolId,
        address payable _refundAddress,
        uint256 _amountLD,
        uint256 _minAmountLD,
        lzTxObj memory _lzTxParams,
        bytes calldata _to,
        bytes calldata _payload
    ) external payable;

    function redeemRemote(
        uint16 _dstChainId,
        uint256 _srcPoolId,
        uint256 _dstPoolId,
        address payable _refundAddress,
        uint256 _amountLP,
        uint256 _minAmountLD,
        bytes calldata _to,
        lzTxObj memory _lzTxParams
    ) external payable;

    function instantRedeemLocal(
        uint16 _srcPoolId,
        uint256 _amountLP,
        address _to
    ) external returns (uint256);

    function redeemLocal(
        uint16 _dstChainId,
        uint256 _srcPoolId,
        uint256 _dstPoolId,
        address payable _refundAddress,
        uint256 _amountLP,
        bytes calldata _to,
        lzTxObj memory _lzTxParams
    ) external payable;

    function sendCredits(
        uint16 _dstChainId,
        uint256 _srcPoolId,
        uint256 _dstPoolId,
        address payable _refundAddress
    ) external payable;

    function quoteLayerZeroFee(
        uint16 _dstChainId,
        uint8 _functionType,
        bytes calldata _toAddress,
        bytes calldata _transferAndCallPayload,
        lzTxObj memory _lzTxParams
    ) external view returns (uint256, uint256);
}

// File: contracts/interfaces/IStrgtPool.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0;

interface IStrgtPool {
    function deltaCredit() external view returns (uint256);

    function totalLiquidity() external view returns (uint256);

    function totalSupply() external view returns (uint256);

    function decimals() external view returns (uint256);

    function poolId() external view returns (uint256);

    function localDecimals() external view returns (uint256);

    function token() external view returns (address);

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

    function approve(address spender, uint256 value) external returns (bool);

    function convertRate() external returns (uint256);
}

// File: contracts/interfaces/IStrgtEthVault.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0;

interface IStrgtEthVault {
    function deposit() external payable;

    function transfer(address to, uint256 value) external returns (bool);

    function withdraw(uint256) external;

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

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

// File: solmate/src/auth/Owned.sol



// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

/// @notice Simple single owner authorization mixin.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/auth/Owned.sol)
abstract contract Owned {
    /*//////////////////////////////////////////////////////////////
                                 EVENTS
    //////////////////////////////////////////////////////////////*/

    event OwnerUpdated(address indexed user, address indexed newOwner);

    /*//////////////////////////////////////////////////////////////
                            OWNERSHIP STORAGE
    //////////////////////////////////////////////////////////////*/

    address public owner;

    modifier onlyOwner() virtual {
        require(msg.sender == owner, "UNAUTHORIZED");

        _;
    }

    /*//////////////////////////////////////////////////////////////
                               CONSTRUCTOR
    //////////////////////////////////////////////////////////////*/

    constructor(address _owner) {
        owner = _owner;

        emit OwnerUpdated(address(0), _owner);
    }

    /*//////////////////////////////////////////////////////////////
                             OWNERSHIP LOGIC
    //////////////////////////////////////////////////////////////*/

    function setOwner(address newOwner) public virtual onlyOwner {
        owner = newOwner;

        emit OwnerUpdated(msg.sender, newOwner);
    }
}

// File: solmate/src/tokens/ERC20.sol



// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

/// @notice Modern and gas efficient ERC20 + EIP-2612 implementation.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/tokens/ERC20.sol)
/// @author Modified from Uniswap (https://github.com/Uniswap/uniswap-v2-core/blob/master/contracts/UniswapV2ERC20.sol)
/// @dev Do not manually set balances without updating totalSupply, as the sum of all user balances must not exceed it.
abstract contract ERC20 {
    /*//////////////////////////////////////////////////////////////
                                 EVENTS
    //////////////////////////////////////////////////////////////*/

    event Transfer(address indexed from, address indexed to, uint256 amount);

    event Approval(address indexed owner, address indexed spender, uint256 amount);

    /*//////////////////////////////////////////////////////////////
                            METADATA STORAGE
    //////////////////////////////////////////////////////////////*/

    string public name;

    string public symbol;

    uint8 public immutable decimals;

    /*//////////////////////////////////////////////////////////////
                              ERC20 STORAGE
    //////////////////////////////////////////////////////////////*/

    uint256 public totalSupply;

    mapping(address => uint256) public balanceOf;

    mapping(address => mapping(address => uint256)) public allowance;

    /*//////////////////////////////////////////////////////////////
                            EIP-2612 STORAGE
    //////////////////////////////////////////////////////////////*/

    uint256 internal immutable INITIAL_CHAIN_ID;

    bytes32 internal immutable INITIAL_DOMAIN_SEPARATOR;

    mapping(address => uint256) public nonces;

    /*//////////////////////////////////////////////////////////////
                               CONSTRUCTOR
    //////////////////////////////////////////////////////////////*/

    constructor(
        string memory _name,
        string memory _symbol,
        uint8 _decimals
    ) {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;

        INITIAL_CHAIN_ID = block.chainid;
        INITIAL_DOMAIN_SEPARATOR = computeDomainSeparator();
    }

    /*//////////////////////////////////////////////////////////////
                               ERC20 LOGIC
    //////////////////////////////////////////////////////////////*/

    function approve(address spender, uint256 amount) public virtual returns (bool) {
        allowance[msg.sender][spender] = amount;

        emit Approval(msg.sender, spender, amount);

        return true;
    }

    function transfer(address to, uint256 amount) public virtual returns (bool) {
        balanceOf[msg.sender] -= amount;

        // Cannot overflow because the sum of all user
        // balances can't exceed the max uint256 value.
        unchecked {
            balanceOf[to] += amount;
        }

        emit Transfer(msg.sender, to, amount);

        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual returns (bool) {
        uint256 allowed = allowance[from][msg.sender]; // Saves gas for limited approvals.

        if (allowed != type(uint256).max) allowance[from][msg.sender] = allowed - amount;

        balanceOf[from] -= amount;

        // Cannot overflow because the sum of all user
        // balances can't exceed the max uint256 value.
        unchecked {
            balanceOf[to] += amount;
        }

        emit Transfer(from, to, amount);

        return true;
    }

    /*//////////////////////////////////////////////////////////////
                             EIP-2612 LOGIC
    //////////////////////////////////////////////////////////////*/

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public virtual {
        require(deadline >= block.timestamp, "PERMIT_DEADLINE_EXPIRED");

        // Unchecked because the only math done is incrementing
        // the owner's nonce which cannot realistically overflow.
        unchecked {
            address recoveredAddress = ecrecover(
                keccak256(
                    abi.encodePacked(
                        "\x19\x01",
                        DOMAIN_SEPARATOR(),
                        keccak256(
                            abi.encode(
                                keccak256(
                                    "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
                                ),
                                owner,
                                spender,
                                value,
                                nonces[owner]++,
                                deadline
                            )
                        )
                    )
                ),
                v,
                r,
                s
            );

            require(recoveredAddress != address(0) && recoveredAddress == owner, "INVALID_SIGNER");

            allowance[recoveredAddress][spender] = value;
        }

        emit Approval(owner, spender, value);
    }

    function DOMAIN_SEPARATOR() public view virtual returns (bytes32) {
        return block.chainid == INITIAL_CHAIN_ID ? INITIAL_DOMAIN_SEPARATOR : computeDomainSeparator();
    }

    function computeDomainSeparator() internal view virtual returns (bytes32) {
        return
            keccak256(
                abi.encode(
                    keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
                    keccak256(bytes(name)),
                    keccak256("1"),
                    block.chainid,
                    address(this)
                )
            );
    }

    /*//////////////////////////////////////////////////////////////
                        INTERNAL MINT/BURN LOGIC
    //////////////////////////////////////////////////////////////*/

    function _mint(address to, uint256 amount) internal virtual {
        totalSupply += amount;

        // Cannot overflow because the sum of all user
        // balances can't exceed the max uint256 value.
        unchecked {
            balanceOf[to] += amount;
        }

        emit Transfer(address(0), to, amount);
    }

    function _burn(address from, uint256 amount) internal virtual {
        balanceOf[from] -= amount;

        // Cannot underflow because a user's balance
        // will never be larger than the total supply.
        unchecked {
            totalSupply -= amount;
        }

        emit Transfer(from, address(0), amount);
    }
}

// File: solmate/src/utils/SafeTransferLib.sol



// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

import {ERC20} from "../tokens/ERC20.sol";

/// @notice Safe ETH and ERC20 transfer library that gracefully handles missing return values.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/SafeTransferLib.sol)
/// @dev Use with caution! Some functions in this library knowingly create dirty bits at the destination of the free memory pointer.
/// @dev Note that none of the functions in this library check that a token has code at all! That responsibility is delegated to the caller.
library SafeTransferLib {
    /*//////////////////////////////////////////////////////////////
                             ETH OPERATIONS
    //////////////////////////////////////////////////////////////*/

    function safeTransferETH(address to, uint256 amount) internal {
        bool success;

        assembly {
            // Transfer the ETH and store if it succeeded or not.
            success := call(gas(), to, amount, 0, 0, 0, 0)
        }

        require(success, "ETH_TRANSFER_FAILED");
    }

    /*//////////////////////////////////////////////////////////////
                            ERC20 OPERATIONS
    //////////////////////////////////////////////////////////////*/

    function safeTransferFrom(
        ERC20 token,
        address from,
        address to,
        uint256 amount
    ) internal {
        bool success;

        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), from) // Append the "from" argument.
            mstore(add(freeMemoryPointer, 36), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 68), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 100 because the length of our calldata totals up like so: 4 + 32 * 3.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 100, 0, 32)
            )
        }

        require(success, "TRANSFER_FROM_FAILED");
    }

    function safeTransfer(
        ERC20 token,
        address to,
        uint256 amount
    ) internal {
        bool success;

        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0xa9059cbb00000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 68 because the length of our calldata totals up like so: 4 + 32 * 2.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 68, 0, 32)
            )
        }

        require(success, "TRANSFER_FAILED");
    }

    function safeApprove(
        ERC20 token,
        address to,
        uint256 amount
    ) internal {
        bool success;

        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0x095ea7b300000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 68 because the length of our calldata totals up like so: 4 + 32 * 2.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 68, 0, 32)
            )
        }

        require(success, "APPROVE_FAILED");
    }
}

// File: solmate/src/utils/FixedPointMathLib.sol



// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

/// @notice Arithmetic library with operations for fixed-point numbers.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/FixedPointMathLib.sol)
/// @author Inspired by USM (https://github.com/usmfum/USM/blob/master/contracts/WadMath.sol)
library FixedPointMathLib {
    /*//////////////////////////////////////////////////////////////
                    SIMPLIFIED FIXED POINT OPERATIONS
    //////////////////////////////////////////////////////////////*/

    uint256 internal constant WAD = 1e18; // The scalar of ETH and most ERC20s.

    function mulWadDown(uint256 x, uint256 y) internal pure returns (uint256) {
        return mulDivDown(x, y, WAD); // Equivalent to (x * y) / WAD rounded down.
    }

    function mulWadUp(uint256 x, uint256 y) internal pure returns (uint256) {
        return mulDivUp(x, y, WAD); // Equivalent to (x * y) / WAD rounded up.
    }

    function divWadDown(uint256 x, uint256 y) internal pure returns (uint256) {
        return mulDivDown(x, WAD, y); // Equivalent to (x * WAD) / y rounded down.
    }

    function divWadUp(uint256 x, uint256 y) internal pure returns (uint256) {
        return mulDivUp(x, WAD, y); // Equivalent to (x * WAD) / y rounded up.
    }

    /*//////////////////////////////////////////////////////////////
                    LOW LEVEL FIXED POINT OPERATIONS
    //////////////////////////////////////////////////////////////*/

    function mulDivDown(
        uint256 x,
        uint256 y,
        uint256 denominator
    ) internal pure returns (uint256 z) {
        assembly {
            // Store x * y in z for now.
            z := mul(x, y)

            // Equivalent to require(denominator != 0 && (x == 0 || (x * y) / x == y))
            if iszero(and(iszero(iszero(denominator)), or(iszero(x), eq(div(z, x), y)))) {
                revert(0, 0)
            }

            // Divide z by the denominator.
            z := div(z, denominator)
        }
    }

    function mulDivUp(
        uint256 x,
        uint256 y,
        uint256 denominator
    ) internal pure returns (uint256 z) {
        assembly {
            // Store x * y in z for now.
            z := mul(x, y)

            // Equivalent to require(denominator != 0 && (x == 0 || (x * y) / x == y))
            if iszero(and(iszero(iszero(denominator)), or(iszero(x), eq(div(z, x), y)))) {
                revert(0, 0)
            }

            // First, divide z - 1 by the denominator and add 1.
            // We allow z - 1 to underflow if z is 0, because we multiply the
            // end result by 0 if z is zero, ensuring we return 0 if z is zero.
            z := mul(iszero(iszero(z)), add(div(sub(z, 1), denominator), 1))
        }
    }

    function rpow(
        uint256 x,
        uint256 n,
        uint256 scalar
    ) internal pure returns (uint256 z) {
        assembly {
            switch x
            case 0 {
                switch n
                case 0 {
                    // 0 ** 0 = 1
                    z := scalar
                }
                default {
                    // 0 ** n = 0
                    z := 0
                }
            }
            default {
                switch mod(n, 2)
                case 0 {
                    // If n is even, store scalar in z for now.
                    z := scalar
                }
                default {
                    // If n is odd, store x in z for now.
                    z := x
                }

                // Shifting right by 1 is like dividing by 2.
                let half := shr(1, scalar)

                for {
                    // Shift n right by 1 before looping to halve it.
                    n := shr(1, n)
                } n {
                    // Shift n right by 1 each iteration to halve it.
                    n := shr(1, n)
                } {
                    // Revert immediately if x ** 2 would overflow.
                    // Equivalent to iszero(eq(div(xx, x), x)) here.
                    if shr(128, x) {
                        revert(0, 0)
                    }

                    // Store x squared.
                    let xx := mul(x, x)

                    // Round to the nearest number.
                    let xxRound := add(xx, half)

                    // Revert if xx + half overflowed.
                    if lt(xxRound, xx) {
                        revert(0, 0)
                    }

                    // Set x to scaled xxRound.
                    x := div(xxRound, scalar)

                    // If n is even:
                    if mod(n, 2) {
                        // Compute z * x.
                        let zx := mul(z, x)

                        // If z * x overflowed:
                        if iszero(eq(div(zx, x), z)) {
                            // Revert if x is non-zero.
                            if iszero(iszero(x)) {
                                revert(0, 0)
                            }
                        }

                        // Round to the nearest number.
                        let zxRound := add(zx, half)

                        // Revert if zx + half overflowed.
                        if lt(zxRound, zx) {
                            revert(0, 0)
                        }

                        // Return properly scaled zxRound.
                        z := div(zxRound, scalar)
                    }
                }
            }
        }
    }

    /*//////////////////////////////////////////////////////////////
                        GENERAL NUMBER UTILITIES
    //////////////////////////////////////////////////////////////*/

    function sqrt(uint256 x) internal pure returns (uint256 z) {
        assembly {
            // Start off with z at 1.
            z := 1

            // Used below to help find a nearby power of 2.
            let y := x

            // Find the lowest power of 2 that is at least sqrt(x).
            if iszero(lt(y, 0x100000000000000000000000000000000)) {
                y := shr(128, y) // Like dividing by 2 ** 128.
                z := shl(64, z) // Like multiplying by 2 ** 64.
            }
            if iszero(lt(y, 0x10000000000000000)) {
                y := shr(64, y) // Like dividing by 2 ** 64.
                z := shl(32, z) // Like multiplying by 2 ** 32.
            }
            if iszero(lt(y, 0x100000000)) {
                y := shr(32, y) // Like dividing by 2 ** 32.
                z := shl(16, z) // Like multiplying by 2 ** 16.
            }
            if iszero(lt(y, 0x10000)) {
                y := shr(16, y) // Like dividing by 2 ** 16.
                z := shl(8, z) // Like multiplying by 2 ** 8.
            }
            if iszero(lt(y, 0x100)) {
                y := shr(8, y) // Like dividing by 2 ** 8.
                z := shl(4, z) // Like multiplying by 2 ** 4.
            }
            if iszero(lt(y, 0x10)) {
                y := shr(4, y) // Like dividing by 2 ** 4.
                z := shl(2, z) // Like multiplying by 2 ** 2.
            }
            if iszero(lt(y, 0x8)) {
                // Equivalent to 2 ** z.
                z := shl(1, z)
            }

            // Shifting right by 1 is like dividing by 2.
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))
            z := shr(1, add(z, div(x, z)))

            // Compute a rounded down version of z.
            let zRoundDown := div(x, z)

            // If zRoundDown is smaller, use it.
            if lt(zRoundDown, z) {
                z := zRoundDown
            }
        }
    }

    function unsafeMod(uint256 x, uint256 y) internal pure returns (uint256 z) {
        assembly {
            // Mod x by y. Note this will return
            // 0 instead of reverting if y is zero.
            z := mod(x, y)
        }
    }

    function unsafeDiv(uint256 x, uint256 y) internal pure returns (uint256 r) {
        assembly {
            // Divide x by y. Note this will return
            // 0 instead of reverting if y is zero.
            r := div(x, y)
        }
    }

    function unsafeDivUp(uint256 x, uint256 y) internal pure returns (uint256 z) {
        assembly {
            // Add 1 to x * y if x % y > 0. Note this will
            // return 0 instead of reverting if y is zero.
            z := add(gt(mod(x, y), 0), div(x, y))
        }
    }
}