# typed: strict
# frozen_string_literal: true

require "abstract_command"
require "fileutils"
require "keg"

module Homebrew
  module Cmd
    class PyenvSync < AbstractCommand
      cmd_args do
        description <<~EOS
          Create symlinks for Homebrew's installed Python versions in `~/.pyenv/versions`.

          Note that older patch version symlinks will be created and linked to the minor
          version so e.g. Python 3.11.0 will also be symlinked to 3.11.3.
        EOS

        named_args :none
      end

      sig { override.void }
      def run
        pyenv_root = Pathname(ENV.fetch("HOMEBREW_PYENV_ROOT", Pathname(Dir.home)/".pyenv"))

        # Don't run multiple times at once.
        pyenv_sync_running = pyenv_root/".pyenv_sync_running"
        return if pyenv_sync_running.exist?

        begin
          pyenv_versions = pyenv_root/"versions"
          pyenv_versions.mkpath
          FileUtils.touch pyenv_sync_running
          HOMEBREW_CELLAR.glob("python{,@*}")
                         .flat_map(&:children)
                         .each { |path| link_pyenv_versions(path, pyenv_versions) }

          pyenv_versions.children
                        .select(&:symlink?)
                        .reject(&:exist?)
                        .each { |path| FileUtils.rm_f path }
        ensure
          pyenv_sync_running.unlink if pyenv_sync_running.exist?
        end
      end

      private

      sig { params(path: Pathname, pyenv_versions: Pathname).void }
      def link_pyenv_versions(path, pyenv_versions)
        pyenv_versions.mkpath

        version = Keg.new(path).version
        major_version = version.major.to_i
        minor_version = version.minor.to_i
        patch_version = version.patch.to_i

        patch_version_range = if Homebrew::EnvConfig.env_sync_strict?
          # Only create symlinks for the exact installed patch version.
          # e.g. 3.11.0 => 3.11.0
          [patch_version]
        else
          # Create folder symlinks for all patch versions to the latest patch version
          # e.g. 3.11.0 => 3.11.3
          0..patch_version
        end

        patch_version_range.each do |patch|
          link_path = pyenv_versions/"#{major_version}.#{minor_version}.#{patch}"

          # Don't clobber existing user installations.
          next if link_path.exist? && !link_path.symlink?

          FileUtils.rm_f link_path
          FileUtils.ln_s path, link_path

          # Create an unversioned symlinks
          # This is what pyenv expects to find in ~/.pyenv/versions/___/bin'.
          # Without this, `python3`, `pip3` do not exist and pyenv falls back to system Python.
          # (eg. python3 -> python3.11, pip3 -> pip3.11)
          executables = %w[python3 pip3 wheel3 idle3 pydoc3]
          executables.each do |executable|
            major_link_path = link_path/"bin/#{executable}"

            # Don't clobber existing user installations.
            next if major_link_path.exist? && !major_link_path.symlink?

            executable_link_path = link_path/"bin/#{executable}.#{minor_version}"
            FileUtils.rm_f major_link_path

            begin
              FileUtils.ln_s executable_link_path, major_link_path
            rescue => e
              opoo "Failed to link #{executable_link_path} to #{major_link_path}: #{e}"
            end
          end
        end
      end
    end
  end
end
