class KPM::BaseInstaller

def install_plugin(plugin_key, specified_group_id=nil, specified_artifact_id=nil, specified_packaging=nil, specified_classifier=nil, specified_version=nil, bundles_dir=nil, specified_type=nil, force_download=false, verify_sha1=true)
  # plugin_key needs to exist
  if plugin_key.nil?
    @logger.warn("Aborting installation: User needs to specify a pluginKey")
    return nil
  end
  # Lookup artifact and perform validation against input
  looked_up_group_id, looked_up_artifact_id, looked_up_packaging, looked_up_classifier, looked_up_version, looked_up_type = KPM::PluginsDirectory.lookup(plugin_key, true)
  return if !validate_installation_arg(plugin_key, 'group_id', specified_group_id, looked_up_group_id)
  return if !validate_installation_arg(plugin_key, 'artifact_id', specified_artifact_id, looked_up_artifact_id)
  return if !validate_installation_arg(plugin_key, 'packaging', specified_packaging, looked_up_packaging)
  return if !validate_installation_arg(plugin_key, 'type', specified_type, looked_up_type)
  return if !validate_installation_arg(plugin_key, 'classifier', specified_classifier, looked_up_classifier)
  # If there is no entry in plugins_directory.yml and the group_id is not the killbill default group_id, the key provided must be a user key and must have a namespace
  if looked_up_artifact_id.nil? &&
      specified_group_id != KPM::BaseArtifact::KILLBILL_JAVA_PLUGIN_GROUP_ID &&
      specified_group_id != KPM::BaseArtifact::KILLBILL_RUBY_PLUGIN_GROUP_ID &&
      plugin_key.split(':').size == 1
    @logger.warn("Aborting installation: pluginKey = #{plugin_key} does not exist in plugin_directory.yml so format of the key must have a user namespace (e.g namespace:key)")
    return nil
  end
  # Specified parameters have always precedence except for the artifact_id (to map stripe to stripe-plugin)
  artifact_id = looked_up_artifact_id || specified_artifact_id
  if artifact_id.nil?
    @logger.warn("Aborting installation: unable to lookup plugin #{specified_artifact_id}")
    return nil
  end
  bundles_dir = Pathname.new(bundles_dir || DEFAULT_BUNDLES_DIR).expand_path
  plugins_dir = bundles_dir.join('plugins')
  type = specified_type || looked_up_type
  if type.to_s == 'java'
    group_id = specified_group_id || looked_up_group_id || KPM::BaseArtifact::KILLBILL_JAVA_PLUGIN_GROUP_ID
    packaging = specified_packaging || looked_up_packaging || KPM::BaseArtifact::KILLBILL_JAVA_PLUGIN_PACKAGING
    classifier = specified_classifier || looked_up_classifier || KPM::BaseArtifact::KILLBILL_JAVA_PLUGIN_CLASSIFIER
    version = specified_version || looked_up_version || LATEST_VERSION
    destination = plugins_dir.join('java').join(artifact_id).join(version)
  else
    group_id = specified_group_id || looked_up_group_id || KPM::BaseArtifact::KILLBILL_RUBY_PLUGIN_GROUP_ID
    packaging = specified_packaging || looked_up_packaging || KPM::BaseArtifact::KILLBILL_RUBY_PLUGIN_PACKAGING
    classifier = specified_classifier || looked_up_classifier || KPM::BaseArtifact::KILLBILL_RUBY_PLUGIN_CLASSIFIER
    version = specified_version || looked_up_version || LATEST_VERSION
    destination = plugins_dir.join('ruby')
  end
  sha1_file = "#{bundles_dir}/#{SHA1_FILENAME}"
  # Before we do the install we verify that the entry we have in the plugin_identifiers.json matches our current request
  coordinates = [group_id, artifact_id, packaging, classifier, version]
  return if !validate_plugin_key(plugins_dir, plugin_key, coordinates)
  @logger.debug("Installing plugin: group_id=#{group_id} artifact_id=#{artifact_id} packaging=#{packaging} classifier=#{classifier} version=#{version} destination=#{destination}")
  artifact_info = KPM::KillbillPluginArtifact.pull(@logger,
                                                   group_id,
                                                   artifact_id,
                                                   packaging,
                                                   classifier,
                                                   version,
                                                   destination,
                                                   sha1_file,
                                                   force_download,
                                                   verify_sha1,
                                                   @nexus_config,
                                                   @nexus_ssl_verify)
  mark_as_active(plugins_dir, artifact_info, artifact_id)
  update_plugin_identifier(plugins_dir, plugin_key, type.to_s, coordinates, artifact_info)
  artifact_info
end