paulfioravanti / resume

require_relative "exceptions"

require_relative "exception_suppressor"

module Resume

  module CLI

    # Module concerned with the installation and dependency checking

    # of Ruby gems on to the system in order to generate the resume.

    #

    # @author Paul Fioravanti

    class GemInstaller

      extend Forwardable

      # @!attribute gems [r]

      # @return [Hash] The hash of gems to install.

      attr_reader :gems

      def self.gem_already_installed?(name, version)

        Gem::Specification.find_by_name(name).version ==

          Gem::Version.new(version)

      end

      private_class_method :gem_already_installed?

      # Initialises a new instance of a Gem Installer.

      #

      # @param gems [Hash]

      #   A hash containing the gem dependencies for the resume.

      # @return [GemInstaller]

      #   The gem installer object.

      # Audits the local system to see if the necessary gems are installed.

      #

      # @return [Hash] The list of remaining gem dependencies to install.

      def audit_gem_dependencies

        gems.each do |name, version|

          # if gem not installed: leave in the gems list

          ExceptionSuppressor.suppress(Gem::LoadError, -> { next }) do

            if self.class.__send__(:gem_already_installed?, name, version)

              # remove dependency to install

              self.gems -= [[name, version]]

            end

          end

        end

      end

      # Outputs the name and version of the gems that must be installed

      # in order to generate the resume.

      #

      # @return [Hash] The list of dependencies to install.

      def output_gem_dependencies

        return if gems.none?

        Output.warning(:ruby_gems)

        gems.each do |name, version|

          Output.plain(:gem_name_and_version, name: name, version: version)

        end

      end

      # Attempts to install gem dependencies and reports back on

      # whether it was successful.

      #

      # @raise [NetworkConnectionError]

      #   if an internet connection is unavailable to download gems.

      # @return [true]

      #   if gem dependencies were successfully installed.

      # @return [false]

      #   if gem dependencies were not successfully installed.

      def gems_successfully_installed?

        return true if gems.none?

        Output.plain(:installing_ruby_gems)

        gems.all? do |gem_name, version|

          Kernel.system("gem", "install", gem_name, "-v", version)

        end

      rescue SocketError, Errno::ECONNREFUSED

        raise NetworkConnectionError

      ensure

        # Reset dir and path values so just-installed gems can

        # be required, but also have this here so that the

        # return value for this method is a boolean

        Gem.clear_paths

      end

      private

      attr_writer :gems

    end

  end

end