require 'rubygems/command'
require 'rubygems/source_index'
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.
    EOF
  end

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

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

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

    gems_to_cleanup = []

    unless options[:args].empty? then
      options[:args].each do |gem_name|
        dep = Gem::Dependency.new gem_name, Gem::Requirement.default
        specs = Gem.source_index.search dep
        specs.each do |spec|
          gems_to_cleanup << spec
        end
      end
    else
      Gem.source_index.each do |name, spec|
        gems_to_cleanup << spec
      end
    end

    gems_to_cleanup = gems_to_cleanup.select { |spec|
      primary_gems[spec.name].version != spec.version
    }

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

    deps = deplist.strongly_connected_components.flatten.reverse

    deps.each do |spec|
      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}",
        }

        if Gem.user_dir == spec.installation_path then
          uninstall_options[:install_dir] = spec.installation_path
        end

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

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

    say "Clean Up Complete"
  end

end

