require 'rubygems/command'
require 'rubygems/dependency_list'
require 'rubygems/uninstaller'

class Gem::Commands::CleanupCommand < Gem::Command

  def initialize
    super 'cleanup',
          'Clean up old versions of installed gems in the local repository',
          :force => false, :install_dir => Gem.dir

    add_option('-d', '--dryrun', "") do |value, options|
      options[:dryrun] = true
    end
  end

  def arguments # :nodoc:
    "GEMNAME       name of gem to cleanup"
  end

  def defaults_str # :nodoc:
    "--no-dryrun"
  end

  def description # :nodoc:
    <<-EOF
The cleanup command removes old gems from GEM_HOME.  If an older version is
installed elsewhere in GEM_PATH the cleanup command won't touch it.

Older gems that are required to satisify the dependencies of gems
are not removed.
    EOF
  end

  def usage # :nodoc:
    "#{program_name} [GEMNAME ...]"
  end

  def execute
    say "Cleaning up installed gems..."
    primary_gems = {}

    Gem::Specification.each do |spec|
      if primary_gems[spec.name].nil? or
         primary_gems[spec.name].version < spec.version then
        primary_gems[spec.name] = spec
      end
    end

    candidate_gems = unless options[:args].empty? then
                       options[:args].map do |gem_name|
                         Gem::Specification.find_all_by_name gem_name
                       end.flatten
                     else
                       Gem::Specification.to_a
                     end

    gems_to_cleanup = candidate_gems.select { |spec|
      !spec.default_gem? and
        primary_gems[spec.name].version != spec.version
    }

    full = Gem::DependencyList.from_specs

    deplist = Gem::DependencyList.new
    gems_to_cleanup.uniq.each do |spec| deplist.add spec end

    deps = deplist.strongly_connected_components.flatten.reverse

    original_home = Gem.dir
    original_path = Gem.path

    deps.each do |spec|
      next unless full.ok_to_remove?(spec.full_name)

      if options[:dryrun] then
        say "Dry Run Mode: Would uninstall #{spec.full_name}"
      else
        say "Attempting to uninstall #{spec.full_name}"

        options[:args] = [spec.name]

        uninstall_options = {
          :executables => false,
          :version => "= #{spec.version}",
        }

        uninstall_options[:user_install] = Gem.user_dir == spec.base_dir

        uninstaller = Gem::Uninstaller.new spec.name, uninstall_options

        begin
          uninstaller.uninstall
        rescue Gem::DependencyRemovalException, Gem::InstallError,
               Gem::GemNotInHomeException, Gem::FilePermissionError => e
          say "Unable to uninstall #{spec.full_name}:"
          say "\t#{e.class}: #{e.message}"
        end
      end

      # Restore path Gem::Uninstaller may have change
      Gem.use_paths(original_home, *original_path)
    end

    say "Clean Up Complete"

    if Gem.configuration.really_verbose then
      skipped = candidate_gems.
        select { |spec| spec.default_gem? }.
        map { |spec| spec.full_name}

      say "Skipped default gems: #{skipped.join ', '}"
    end
  end

end