Added tab-completions for ZSH.

[propensive]

The installation instructions in the README file are experimental. They
worked for me, though I don't know how special my own configuration is.

The will also be some maintenance overhead involved with this. As
parameters change, the zsh-completions file will need to change with
them. In the long-term, maybe we could auto-generate this file somehow
(for example, by parsing the output from bloop <subcommand> --help),
but for now we should probalbly merge early and get feedback sooner.

The definitions for the ZSH completions involve really ugly code. Any
improvements would be very welcome.

You may want to make an additional change after merging this. Having
bloop, bloop-server and bloop-shell all on the PATH at the same
time means that (assuming there are no other commands beginnig with
blo), typing blo<tab> will autocomplete to bloop without a space
after it, because of the bloop-server and bloop-shell completions.

If bloop-server and bloop-shell were to be renamed to, say,
blp-server and blp-shell respectively, then blo<tab> would take
you straight to the subcommands list, inevitably saving you valuable
microseconds. # Please enter the commit message for your changes. Lines
starting.

[propensive]

Renaming bloop-server and bloop-shell to blp-server and blp-shell in the obvious way (search and replace) worked, so I'm including this in the PR, too.

[Duhemm]

Thanks, that's really great!

Renaming bloop-server and bloop-shell (this one is going away anyway) is probably the way to go given how much it'll improve the shell completion.

It'd also be great to be able to generate the completion. I imagine it'd be doable to inspect bloop.cli.Commands via reflection and generate the completions. Or add that directly in CaseApp? If it sounds too complicated, I think that we can leave generation of completions for another PR. I don't expect that we'll be adding that many more commands and options in the near future... It'd definitely be nice to have though.

Finally, it'd be awesome if the brew formula took care of installing the completions. There's support for that in Homebrew, see this example:
https://github.com/Homebrew/homebrew-core/blob/ee727e0f8985027fc889b0c35d7eaacdef4c0d02/Formula/kerl.rb#L10-L14

I'm happy to take care of that if you don't have a Mac 😄

[Duhemm]

Why did you remove the comma here? (between -c and --config-dir)

[propensive]

That was a mistake, actually! Though it seems to work anyway... ;)

[Duhemm]

👍 👍 👍

[jvican]

This is something that was on the todo list, so thank you for submitting a PR. I echo Martin's idea of autogenerating the autocompletions rather than making them explicit. This should not take a lot of time, Scalafix has already done the hard work. For a caseapp integration, could you emulate what Scalafix does @propensive https://github.com/scalacenter/scalafix/blob/master/scalafix-cli/src/main/scala/scalafix/cli/Cli.scala#L70-L159 ?

[olafurpg]

I would recommend to merge the manual static completions for now since they already improve the state of the art. Then open a ticket to discuss how to how to automatically keep the completions up to do date, case-app provides all the necessary information to generate completion files.

Another interesting topic worth discussing is that bloop is always hot via nailgun, so I think you can also complete dynamic information such as project IDs 🔥

[jvican]

Another interesting topic worth discussing is that bloop is always hot via nailgun, so I think you can also complete dynamic information such as project IDs

Unfortunately, I don't this is possible without rewriting the nailgun protocol... Would be cool to experiment with it when bloop is stable, but writing my own custom nailgun protocol is something I'd like to avoid 🤔.

@propensive I defer merging this to @Duhemm, this looks good to me! Let's tackle the scalable solution in another PR.

[propensive]

I'm actually tending towards the answer I've just given on coursier completions.

I agree that autogeneration is the best long-term solution, though I'd like to treat it separately for now. I think it needs a bit more work than what Olaf's already done for the same support currently in these completions, but that shouldn't stop anything right now.

So, in case it's not clear, I'm going to propose:

1. move this to a "completions-for-scala-tools" project
2. leave the PR open for now
3. look towards autogenerating the completions in the future

Regarding (3), this would typically work by providing a (probably a bit secret) subcommand, such as,

bloop completions --zsh

or

bloop completions --bash

which would spit out the completions commands relating to that version of bloop. Meanwhile, the bloop script in the ZSH-completions project would be written to simply call bloop completions --zsh, and it could then use them.

So, leave this PR unmerged for now, and I'll get to work on a more general ZSH bundle for Scala users.

[jvican]

Hey Jon, are you sure you don't wanna merge this? It looks good as it is.

[propensive]

If you think it's worth including now, go for it. :) I intend to look into better long-term solutions, but it probably makes sense to merge this now, and remove it if and when those long-term solutions materialize.

[Duhemm]

Awesome, @jvican brought the CI back from its vacation :)

LGTM!

Just a side-note when generating the completion: It'd be better if the generation was a command from the server rather than from the Bloop CLI. This way, it's easier to generate while installation with, say, homebrew.

[propensive]

@Duhemm Thank you!