Allow changing of volume in different steps

[DOD-101]

Resolves #616

This change implements what was requested in #616, but would require users to re-write their keymap.toml.

The new format for keymap.tomlwould be:

[[keymaps]]
key_sequence = "+"
command = { type = "VolumeChange", args = { offset = 1 } }

[[keymaps]]
key_sequence = "-"
command = { type = "VolumeChange", args = { offset = -1 } }

[[keymaps]]
key_sequence = "n"
command = { type = "NextTrack" }

I'm looking for input on whether this is a good idea to implement this way. Or if an alternative would be better.

There is also the option of leaving the configuration syntax as is and setting the offset like this:

[[keymaps]]
key_sequence = "+"
command = "VolumeChange 1"

And this approach has some advantages and disadvantages.

For one, the config format for the other commands wouldn't change, but as far as I can tell I would have to write some custom deserialization logic, since TOML doesn't support this syntax out of the box. And any future commands, which have arguments, would need to do the same.

Personally, I don't have a preference either way.

[DOD-101]

So I went ahead a wrote the deserialize function needed for the alternative syntax. It's not pretty, but it's a proof of concept.

I will say that I don't have any real experience with serde, so there might be a far better way of doing this:

impl<'de> Deserialize<'de> for Command {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        let input = String::deserialize(deserializer)?;
        let parts: Vec<&str> = input.split_whitespace().collect();

        let variant_name = parts[0];

        match variant_name {
            "VolumeChange" => {
                let offset = parts
                    .get(1)
                    .ok_or(serde::de::Error::custom("No offset Provided"))?
                    .parse::<i32>()
                    .map_err(|_| serde::de::Error::custom("Failed to parse offset"))?;
                Ok(Command::VolumeChange { offset })
            }
            "None" => Ok(Command::None),
            "NextTrack" => Ok(Command::NextTrack),
            "PreviousTrack" => Ok(Command::PreviousTrack),
            "ResumePause" => Ok(Command::ResumePause),
            "PlayRandom" => Ok(Command::PlayRandom),
            "Repeat" => Ok(Command::Repeat),
            "ToggleFakeTrackRepeatMode" => Ok(Command::ToggleFakeTrackRepeatMode),
            "Shuffle" => Ok(Command::Shuffle),
            "Mute" => Ok(Command::Mute),
            "SeekForward" => Ok(Command::SeekForward),
            "SeekBackward" => Ok(Command::SeekBackward),
            "Quit" => Ok(Command::Quit),
            "ClosePopup" => Ok(Command::ClosePopup),
            #[cfg(feature = "streaming")]
            "RestartIntegratedClient" => Ok(Command::RestartIntegratedClient),
            "SelectNextOrScrollDown" => Ok(Command::SelectNextOrScrollDown),
            "SelectPreviousOrScrollUp" => Ok(Command::SelectPreviousOrScrollUp),
            "PageSelectNextOrScrollDown" => Ok(Command::PageSelectNextOrScrollDown),
            "PageSelectPreviousOrScrollUp" => Ok(Command::PageSelectPreviousOrScrollUp),
            "SelectFirstOrScrollToTop" => Ok(Command::SelectFirstOrScrollToTop),
            "SelectLastOrScrollToBottom" => Ok(Command::SelectLastOrScrollToBottom),
            "ChooseSelected" => Ok(Command::ChooseSelected),
            "JumpToCurrentTrackInContext" => Ok(Command::JumpToCurrentTrackInContext),
            "RefreshPlayback" => Ok(Command::RefreshPlayback),
            "ShowActionsOnSelectedItem" => Ok(Command::ShowActionsOnSelectedItem),
            "ShowActionsOnCurrentTrack" => Ok(Command::ShowActionsOnCurrentTrack),
            "AddSelectedItemToQueue" => Ok(Command::AddSelectedItemToQueue),
            "FocusNextWindow" => Ok(Command::FocusNextWindow),
            "FocusPreviousWindow" => Ok(Command::FocusPreviousWindow),
            "SwitchTheme" => Ok(Command::SwitchTheme),
            "SwitchDevice" => Ok(Command::SwitchDevice),
            "Search" => Ok(Command::Search),
            "BrowseUserPlaylists" => Ok(Command::BrowseUserPlaylists),
            "BrowseUserFollowedArtists" => Ok(Command::BrowseUserFollowedArtists),
            "BrowseUserSavedAlbums" => Ok(Command::BrowseUserSavedAlbums),
            "CurrentlyPlayingContextPage" => Ok(Command::CurrentlyPlayingContextPage),
            "TopTrackPage" => Ok(Command::TopTrackPage),
            "RecentlyPlayedTrackPage" => Ok(Command::RecentlyPlayedTrackPage),
            "LikedTrackPage" => Ok(Command::LikedTrackPage),
            #[cfg(feature = "lyric-finder")]
            "LyricPage" => Ok(Command::LyricPage),
            "LibraryPage" => Ok(Command::LibraryPage),
            "SearchPage" => Ok(Command::SearchPage),
            "BrowsePage" => Ok(Command::BrowsePage),
            "Queue" => Ok(Command::Queue),
            "OpenCommandHelp" => Ok(Command::OpenCommandHelp),
            "PreviousPage" => Ok(Command::PreviousPage),
            "OpenSpotifyLinkFromClipboard" => Ok(Command::OpenSpotifyLinkFromClipboard),
            "SortTrackByTitle" => Ok(Command::SortTrackByTitle),
            "SortTrackByArtists" => Ok(Command::SortTrackByArtists),
            "SortTrackByAlbum" => Ok(Command::SortTrackByAlbum),
            "SortTrackByDuration" => Ok(Command::SortTrackByDuration),
            "SortTrackByAddedDate" => Ok(Command::SortTrackByAddedDate),
            "ReverseTrackOrder" => Ok(Command::ReverseTrackOrder),
            "MovePlaylistItemUp" => Ok(Command::MovePlaylistItemUp),
            "MovePlaylistItemDown" => Ok(Command::MovePlaylistItemDown),
            "CreatePlaylist" => Ok(Command::CreatePlaylist),
            _ => Err(serde::de::Error::custom(format!(
                "Unknown variant: {}",
                variant_name
            ))),
        }
    }
}

[aome510]

Suggested change

	_ => unreachable!(),
	Self::VolumeChange { .. } => unreachable!(),

enum handling is preferred to be explicit to avoid misuse, e.g. forgetting to handle new variants