IAdvancedWETH.sol

pragma solidity >=0.4.0;

/// @title Advanced WETH Interface
/// @author Moody Salem
/// @notice Unlocks additional features for Wrapped Ether, or WETH, that allow you to interact with contracts that
///     use WETH transparently as if you were using ETH. Approve this contract to spend your WETH to use.
/// @dev The underlying assumption is that the user wants to use ETH and avoid unnecessary approvals, but ERC20 is
///     required to interact with many protocols. This contract enables a user to interact with protocols consuming
///     ERC20 without additional approvals.
interface IAdvancedWETH {
    /// @notice Returns the WETH contract that this Advanced WETH contract uses.
    /// @dev Returns the WETH contract that this Advanced WETH contract uses.
    /// @return the WETH contract used by this contract.
    function weth() external view returns (address payable);

    /// @notice Deposits any ETH sent to the contract, and transfers additional WETH from the caller,
    ///     and then approves and calls another contract `to` with data `data`.
    /// @dev Use this method to spend a combination of ETH and WETH as WETH. Refunds any unspent WETH to the caller as
    ///     ETH. Note that either `amount` or `msg.value` may be 0, but not both.
    /// @param amount The amount to transfer from the caller to this contract and approve for the `to` address, or 0.
    /// @param to The address to approve and call after minting WETH
    /// @param data The data to forward to the contract after minting WETH
    function depositAndTransferFromThenCall(uint amount, address to, bytes calldata data) external payable;

    /// @notice Unwrap and forward all WETH held by the contract to the given address. This should never be called
    ///     directly, but rather as a callback from a contract call that results in sending WETH to this contract.
    /// @dev Use this method as a callback from other contracts to unwrap WETH before forwarding to the user.
    /// @param to The address that should receive the unwrapped ETH.
    function withdrawTo(address payable to) external;
}