// File: contracts/WethLoanRouter.sol



pragma solidity ^0.8.3;

import "./interfaces/IWethLoanRouter.sol";
import "./interfaces/ILoanRouter.sol";
import "./interfaces/IBondController.sol";
import "./interfaces/ITranche.sol";
import "./interfaces/IButtonWrapper.sol";
import "./interfaces/IWETH9.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@rari-capital/solmate/src/utils/SafeTransferLib.sol";
import "@rari-capital/solmate/src/tokens/ERC20.sol";

/**
 * @dev Weth Loan Router built on top of a LoanRouter of your choosing
 * to allow loans to be created with raw ETH instead of WETH
 */
contract WethLoanRouter is IWethLoanRouter {
    ILoanRouter public immutable loanRouter;
    IWETH9 public immutable weth;

    /**
     * @dev Constructor for setting underlying loanRouter and weth contracts
     * @param _loanRouter The underlying loanRouter that does all the wrapping and trading
     * @param _weth The WETH contract to wrap ETH in
     */
    constructor(ILoanRouter _loanRouter, IWETH9 _weth) {
        loanRouter = _loanRouter;
        weth = _weth;
    }

    /**
     * @inheritdoc IWethLoanRouter
     */
    function wrapAndBorrow(
        IBondController bond,
        IERC20 currency,
        uint256[] memory sales,
        uint256 minOutput
    ) external payable override returns (uint256 amountOut) {
        uint256 wethBalance = _wethWrapAndApprove();
        amountOut = loanRouter.wrapAndBorrow(wethBalance, bond, currency, sales, minOutput);
        require(amountOut >= minOutput, "WethLoanRouter: Insufficient output");
        _distributeLoanOutput(amountOut, bond, currency);
        return amountOut;
    }

    /**
     * @inheritdoc IWethLoanRouter
     */
    function wrapAndBorrowMax(
        IBondController bond,
        IERC20 currency,
        uint256 minOutput
    ) external payable override returns (uint256 amountOut) {
        uint256 wethBalance = _wethWrapAndApprove();
        amountOut = loanRouter.wrapAndBorrowMax(wethBalance, bond, currency, minOutput);
        require(amountOut >= minOutput, "WethLoanRouter: Insufficient output");
        _distributeLoanOutput(amountOut, bond, currency);
        return amountOut;
    }

    /**
     * @dev Wraps the ETH that was transferred to this contract and then approves loanRouter for entire amount
     * @dev No need to check that bond's collateral has WETH as underlying since deposit will fail otherwise
     * @return WETH balance that was wrapped. Equal to loanRouter allowance for WETH.
     */
    function _wethWrapAndApprove() internal returns (uint256) {
        // Confirm that ETH was sent
        uint256 value = msg.value;
        require(value > 0, "ButtonTokenWethRouter: No ETH supplied");

        // Wrapping ETH into weth
        weth.deposit{ value: value }();

        // Approve loanRouter to take weth
        uint256 wethBalance = weth.balanceOf(address(this));
        weth.approve(address(loanRouter), wethBalance);
        return wethBalance;
    }

    /**
     * @dev Distributes tranche balances and borrowed amounts to end-user
     * @param amountOut The output amount that is being borrowed
     * @param bond The bond that is being borrowed from
     * @param currency The asset being borrowed
     */
    function _distributeLoanOutput(
        uint256 amountOut,
        IBondController bond,
        IERC20 currency
    ) internal {
        // Send loan currenncy out from this contract to msg.sender
        SafeTransferLib.safeTransfer(ERC20(address(currency)), msg.sender, amountOut);

        // Send out the tranche tokens from this contract to the msg.sender
        ITranche tranche;
        for (uint256 i = 0; i < bond.trancheCount(); i++) {
            (tranche, ) = bond.tranches(i);
            SafeTransferLib.safeTransfer(ERC20(address(tranche)), msg.sender, tranche.balanceOf(address(this)));
        }
    }
}

// File: contracts/interfaces/IWethLoanRouter.sol



pragma solidity 0.8.3;

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

/**
 * @dev Router for creating loans with tranche
 */
interface IWethLoanRouter {
    /**
     * @notice Borrow against a given bond, wrapping the raw ETH collateral into a WETH ButtonToken first
     * @param bond The bond to borrow from
     * @param currency The asset to borrow
     * @param sales The number of tranche tokens to sell, in tranche index order
     * @param minOutput The minimum amount of currency to get out, reverts if not met
     */
    function wrapAndBorrow(
        IBondController bond,
        IERC20 currency,
        uint256[] memory sales,
        uint256 minOutput
    ) external payable returns (uint256 amountOut);

    /**
     * @notice Borrow as much as possible against a given bond,
     *  wrapping the raw ETH collateral into a WETH ButtonToken first
     * @param bond The bond to borrow from
     * @param currency The asset to borrow
     * @param minOutput The minimum amount of currency to get out, reverts if not met
     */
    function wrapAndBorrowMax(
        IBondController bond,
        IERC20 currency,
        uint256 minOutput
    ) external payable returns (uint256 amountOut);
}

// File: contracts/interfaces/ILoanRouter.sol



pragma solidity 0.8.3;

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

/**
 * @dev Router for creating loans with tranche
 */
interface ILoanRouter {
    /**
     * @dev Borrow against a given bond, wrapping the raw collateral into a ButtonToken first
     * @param underlyingAmount The amount of collateral to deposit into the bond
     * @param bond The bond to borrow from
     * @param currency The asset to borrow
     * @param sales The number of tranche tokens to sell, in tranche index order
     * @param minOutput The minimum amount of currency to get out, reverts if not met
     */
    function wrapAndBorrow(
        uint256 underlyingAmount,
        IBondController bond,
        IERC20 currency,
        uint256[] memory sales,
        uint256 minOutput
    ) external returns (uint256 amountOut);

    /**
     * @dev Borrow as much as possible against a given bond, wrapping the raw collateral into a ButtonToken first
     * @param underlyingAmount The amount of collateral to deposit into the bond
     * @param bond The bond to borrow from
     * @param currency The asset to borrow
     * @param minOutput The minimum amount of currency to get out, reverts if not met
     */
    function wrapAndBorrowMax(
        uint256 underlyingAmount,
        IBondController bond,
        IERC20 currency,
        uint256 minOutput
    ) external returns (uint256 amountOut);

    /**
     * @dev Borrow against a given bond
     * @param amount The amount of collateral to deposit into the bond
     * @param bond The bond to borrow from
     * @param currency The asset to borrow
     * @param sales The number of tranche tokens to sell, in tranche index order
     * @param minOutput The minimum amount of currency to get out, reverts if not met
     */
    function borrow(
        uint256 amount,
        IBondController bond,
        IERC20 currency,
        uint256[] memory sales,
        uint256 minOutput
    ) external returns (uint256 amountOut);

    /**
     * @dev Borrow as much as possible against a given bond
     * @param amount The amount of collateral to deposit into the bond
     * @param bond The bond to borrow from
     * @param currency The asset to borrow
     * @param minOutput The minimum amount of currency to get out, reverts if not met
     */
    function borrowMax(
        uint256 amount,
        IBondController bond,
        IERC20 currency,
        uint256 minOutput
    ) external returns (uint256 amountOut);
}

// File: contracts/interfaces/IBondController.sol



pragma solidity 0.8.3;

import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@uniswap/lib/contracts/libraries/TransferHelper.sol";
import "./ITranche.sol";

struct TrancheData {
    ITranche token;
    uint256 ratio;
}

/**
 * @dev Controller for a ButtonTranche bond system
 */
interface IBondController {
    event Deposit(address from, uint256 amount, uint256 feeBps);
    event Mature(address caller);
    event RedeemMature(address user, address tranche, uint256 amount);
    event Redeem(address user, uint256[] amounts);
    event FeeUpdate(uint256 newFee);

    function collateralToken() external view returns (address);

    function tranches(uint256 i) external view returns (ITranche token, uint256 ratio);

    function trancheCount() external view returns (uint256 count);

    function feeBps() external view returns (uint256 fee);

    /**
     * @dev Deposit `amount` tokens from `msg.sender`, get tranche tokens in return
     * Requirements:
     *  - `msg.sender` must have `approved` `amount` collateral tokens to this contract
     */
    function deposit(uint256 amount) external;

    /**
     * @dev Matures the bond. Disables deposits,
     * fixes the redemption ratio, and distributes collateral to redemption pools
     * Redeems any fees collected from deposits, sending redeemed funds to the contract owner
     * Requirements:
     *  - The bond is not already mature
     *  - One of:
     *      - `msg.sender` is owner
     *      - `maturityDate` has passed
     */
    function mature() external;

    /**
     * @dev Redeems some tranche tokens
     * Requirements:
     *  - The bond is mature
     *  - `msg.sender` owns at least `amount` tranche tokens from address `tranche`
     *  - `tranche` must be a valid tranche token on this bond
     */
    function redeemMature(address tranche, uint256 amount) external;

    /**
     * @dev Redeems a slice of tranche tokens from all tranches.
     *  Returns collateral to the user proportionally to the amount of debt they are removing
     * Requirements
     *  - The bond is not mature
     *  - The number of `amounts` is the same as the number of tranches
     *  - The `amounts` are in equivalent ratio to the tranche order
     */
    function redeem(uint256[] memory amounts) external;

    /**
     * @dev Updates the fee taken on deposit to the given new fee
     *
     * Requirements
     * - `msg.sender` has admin role
     * - `newFeeBps` is in range [0, 50]
     */
    function setFee(uint256 newFeeBps) external;
}

// File: contracts/interfaces/ITranche.sol



pragma solidity 0.8.3;

import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@uniswap/lib/contracts/libraries/TransferHelper.sol";

/**
 * @dev ERC20 token to represent a single tranche for a ButtonTranche bond
 *
 */
interface ITranche is IERC20 {
    /**
     * @dev returns the BondController address which owns this Tranche contract
     *  It should have admin permissions to call mint, burn, and redeem functions
     */
    function bond() external view returns (address);

    /**
     * @dev Mint `amount` tokens to `to`
     *  Only callable by the owner (bond controller). Used to
     *  manage bonds, specifically creating tokens upon deposit
     * @param to the address to mint tokens to
     * @param amount The amount of tokens to mint
     */
    function mint(address to, uint256 amount) external;

    /**
     * @dev Burn `amount` tokens from `from`'s balance
     *  Only callable by the owner (bond controller). Used to
     *  manage bonds, specifically burning tokens upon redemption
     * @param from The address to burn tokens from
     * @param amount The amount of tokens to burn
     */
    function burn(address from, uint256 amount) external;

    /**
     * @dev Burn `amount` tokens from `from` and return the proportional
     * value of the collateral token to `to`
     * @param from The address to burn tokens from
     * @param to The address to send collateral back to
     * @param amount The amount of tokens to burn
     */
    function redeem(
        address from,
        address to,
        uint256 amount
    ) external;
}

// File: contracts/interfaces/IButtonWrapper.sol



// SPDX-License-Identifier: GPL-3.0-or-later
// from https://github.com/buttonwood-protocol/button-wrappers

// Interface definition for ButtonWrapper contract, which wraps an
// underlying ERC20 token into a new ERC20 with different characteristics.
// NOTE: "uAmount" => underlying token (wrapped) amount and
//       "amount" => wrapper token amount
interface IButtonWrapper {
    /// @notice Transfers underlying tokens from {msg.sender} to the contract and
    ///         mints wrapper tokens to the specified beneficiary.
    /// @param uAmount The amount of underlying tokens to deposit.
    /// @return The amount of wrapper tokens mint.
    function deposit(uint256 uAmount) external returns (uint256);

    /// @return The address of the underlying token.
    function underlying() external view returns (address);
}

// File: contracts/interfaces/IWETH9.sol



// SPDX-License-Identifier: GPL-3.0-or-later
// derived from https://github.com/gnosis/canonical-weth/

// Interface definition for WETH contract, which wraps ETH into an ERC20 token.
interface IWETH9 {
    function deposit() external payable;

    function withdraw(uint256 wad) external;

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

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

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

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

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

    /**
     * @dev Moves `amount` tokens from the caller's account to `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 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);
}

// File: @rari-capital/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/Rari-Capital/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: @rari-capital/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/Rari-Capital/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: @openzeppelin/contracts/utils/Context.sol



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

pragma solidity ^0.8.0;

/**
 * @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;
    }
}

// File: @uniswap/lib/contracts/libraries/TransferHelper.sol



// SPDX-License-Identifier: GPL-3.0-or-later

pragma solidity >=0.6.0;

// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
library TransferHelper {
    function safeApprove(
        address token,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('approve(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::safeApprove: approve failed'
        );
    }

    function safeTransfer(
        address token,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('transfer(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::safeTransfer: transfer failed'
        );
    }

    function safeTransferFrom(
        address token,
        address from,
        address to,
        uint256 value
    ) internal {
        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(
            success && (data.length == 0 || abi.decode(data, (bool))),
            'TransferHelper::transferFrom: transferFrom failed'
        );
    }

    function safeTransferETH(address to, uint256 value) internal {
        (bool success, ) = to.call{value: value}(new bytes(0));
        require(success, 'TransferHelper::safeTransferETH: ETH transfer failed');
    }
}