ockam completion --shell {bash|zsh|fish} command for shell completion

[mrinalwadhwa]

Current Behaviour

Users have to type the full ockam commands

Desired Behaviour

Generate shell completion scripts for various shells

ockam completion --shell {bash|zsh|fish}

This would require adding the completion command here:
https://github.com/build-trust/ockam/tree/develop/implementations/rust/ockam/ockam_command/src

Clap Complete seems to have everything we need for this.
https://github.com/clap-rs/clap/tree/master/clap_complete

After this command exists we can also look at adding it to our homebrew formula
https://github.com/build-trust/homebrew-ockam/blob/main/ockam.rb

Github's gh completion command seems good to model ockam completion behavior after
https://cli.github.com/manual/gh_completion

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[datdhruv]

Hi!, Can this be assigned to me?

[mrinalwadhwa]

@datdhruv of course, all yours. Looking forward to the pull request. Let us know if you have questions along the way.

[mrinalwadhwa]

@datdhruv checking in to see if you still have time to work on this issue or do you have any questions.

If you're busy that's completely okay. We can open this issue for someone else to pick up and then whenever you're available again I'd be happy suggest other issues you could contribute to.

[datdhruv]

Hey, should be ready with a commit today

[mrinalwadhwa]

Awesome, looking forward to the PR 🐰

[datdhruv]

One question,

clap_complete has a method generate which expects the shell, a reference to a Clap::App, the name of the bin file and output stream.

generate(Shell::Bash, &mut ockam_command, "ockam", &mut io::stdout())

From what i gather we dont use a clap::App in the classical sense

(classic sense => something like this)

pub fn make_subcommand<'help>() -> App<'help> {
    App::new("init")
        .about("Creates the boilerplate structure and files for a new book")
        // the {n} denotes a newline which will properly aligned in all help messages
        .arg(arg!([dir]
            "Directory to create the book in{n}\
            (Defaults to the Current Directory when omitted)"
        ))
        .arg(arg!(--theme "Copies the default theme into your source folder"))
        .arg(arg!(--force "Skips confirmation prompts"))
        .arg(
            Arg::new("title")
                .long("title")
                .takes_value(true)
                .help("Sets the book title")
                .required(false),
        )
        .arg(
            Arg::new("ignore")
                .long("ignore")
                .takes_value(true)
                .possible_values(&["none", "git"])
                .help("Creates a VCS ignore file (i.e. .gitignore)")
                .required(false),
        )
}

from https://github.com/rust-lang/mdBook/blob/4c303c3b1dde1cbdf2f593b05687340915b93417/src/cmd/init.rs#L12

How would I create a reference to the clap::app? (right now ockam_command is of type struct:OckamCommand

[mrinalwadhwa]

@datdhruv I found this on the Clap discussions group clap-rs/clap#3671 (comment)

Deriving Parser also derives the trait CommandFactory which has the CommandFactory::command function.

[datdhruv]

#3326 and #3327 should take care of this, so we can close this