# frozen_string_literal: true

module Launchy
  module Detect
    #
    # Detect the current desktop environment for *nix machines
    # Currently this is Linux centric. The detection is based upon the detection
    # used by xdg-open from http://portland.freedesktop.org/
    class NixDesktopEnvironment
      class NotFoundError < Launchy::Error; end

      extend ::Launchy::DescendantTracker

      # Detect the current *nix desktop environment
      #
      # If the current dekstop environment be detected, the return
      # NixDekstopEnvironment::Unknown
      def self.detect
        found = find_child(:is_current_desktop_environment?)
        Launchy.log("Current Desktop environment not found. #{Launchy.bug_report_message}") unless found
        found
      end

      def self.fallback_browsers
        %w[firefox iceweasel seamonkey opera mozilla netscape galeon links lynx].map { |x| ::Launchy::Argv.new(x) }
      end

      def self.browsers
        [browser, fallback_browsers].flatten
      end

      #---------------------------------------
      # The list of known desktop environments
      #---------------------------------------

      # KDE desktop environment
      class Kde < NixDesktopEnvironment
        def self.is_current_desktop_environment?
          ENV.fetch("KDE_FULL_SESSION", nil) &&
            Launchy::Application.find_executable("kde-open")
        end

        def self.browser
          ::Launchy::Argv.new("kde-open")
        end
      end

      # Gnome desktop environment
      class Gnome < NixDesktopEnvironment
        def self.is_current_desktop_environment?
          ENV.fetch("GNOME_DESKTOP_SESSION_ID", nil) &&
            Launchy::Application.find_executable("gnome-open")
        end

        def self.browser
          ::Launchy::Argv.new("gnome-open")
        end
      end

      # Xfce desktop environment
      class Xfce < NixDesktopEnvironment
        def self.is_current_desktop_environment?
          if Launchy::Application.find_executable("xprop")
            `xprop -root _DT_SAVE_MODE`.include?("xfce")
          else
            false
          end
        end

        def self.browser
          ::Launchy::Argv.new(%w[exo-open --launch WebBrowser])
        end
      end

      # Fall back environment as the last case
      class Xdg < NixDesktopEnvironment
        def self.is_current_desktop_environment?
          Launchy::Application.find_executable(browser)
        end

        def self.browser
          ::Launchy::Argv.new("xdg-open")
        end
      end

      # The one that is found when all else fails. And this must be declared last
      class NotFound < NixDesktopEnvironment
        def self.is_current_desktop_environment?
          true
        end

        def self.browser
          ::Launchy::Argv.new
        end
      end
    end
  end
end