Add Swift Plugin support

[csjones]

⚡ Summary

Thank you for making such an exceptional tool. While I primarily develop in Swift, I've recently created a wrapper plugin for Lefthook that can be included in Swift packages.

https://github.com/csjones/lefthook

Value

Direct Swift Package Manager support instead of relying on installation methods like go get, brew, npm, or gem.

Behavior and configuration changes

At minimum, the primary change would be in the hooks.tmpl file:

  elif swift package plugin lefthook >/dev/null 2>&1
  then
    swift package --disable-sandbox plugin lefthook $@
  else

Additional changes are dependent on whether it makes sense for a Swift plugin to live along side npm and rubygems implementations in this repository. This would include a Package.swift manifest file in the root of the repository and CI additions to create a lefthook.artifactbundle.zip file.

Alternatively, I could create a wrapper plugin package that downloads the Lefthook release binaries and implements all the swift details in a separate repository.

[csjones]

I've investigated and implemented the wrapper plugin approach here: https://github.com/csjones/lefthook-plugin

So far, the lefthook swift plugin is working well on macOS and Linux.

[mrexox]

Hey @csjones, this is amazing! Do you want to keep your plugin in your repo or integrate it into lefthook repo?

[csjones]

Hey @mrexox, now having tried both approaches, I'm leaning more towards the plugin in the repo I created than the lefthook repo. Should I open a PR for the changes to hooks.tmpl?

[mrexox]

@csjones , yes, that will be great. It would be also good to add a note into docs/installation.md and reference your repo there

[csjones]

@mrexox done!