New class to check, ask and install a UI extension

library/general/src/lib/ui/ui_extension_checker.rb

@@ -0,0 +1,138 @@
+# ------------------------------------------------------------------------------
+# Copyright (c) 2021 SUSE LLC
+#
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of version 2 of the GNU General Public License as published by the
+# Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+#
+# ------------------------------------------------------------------------------
+
+require "yast"
+require "yast2/ui_plugin_info"
+
+Yast.import "Package"
+Yast.import "Report"
+Yast.import "Popup"
+
+module Yast
+  # Class to check if a UI extension plug-in ("pkg", "graph") is installed.
+  # If it's not installed, ask the user if the package containing it should be
+  # installed and (if the user answers "yes") install it.
+  #
+  class UIExtensionChecker
+    include Yast::Logger
+    include Yast::I18n
+
+    # Constructor: Create a UI extension checker for the specified extension.
+    #
+    # @param ext_name [String] Short name of the UI extension ("pkg", "graph")
+    #
+    def initialize(ext_name)
+      textdomain "base"
+      @ext_name = ext_name
+      @ok = false
+      @ui_plugin_info = UIPluginInfo.new
+      ensure_ext_installed
+    end
+
+    # Check if the UI extension was either installed to begin with or if the
+    # user (after being asked) confirmed to install it, and it was installed
+    # successfully.
+    #
+    # @return [Boolean] UI extension is available now
+    #
+    def ok?
+      @ok
+    end
+
+  private
+
+    # Ensure that the UI extension is installed: If it isn't installed yet
+    # anyway, ask the user if it should be installed and if yes, install it.
+    #
+    # @return [Boolean] UI extension is available now (same as ok?)
+    #
+    def ensure_ext_installed
+      return if installed?
+
+      if available_for_ui?
+        ask && install
+      else
+        not_available_error
+      end
+      @ok
+    end
+
+    # Check if the UI extension plug-in is installed.
+    # This also sets @ok.
+    #
+    # @return [Boolean] true if the UI extension is already installed, false if not
+    #
+    def installed?
+      ext_plugin = @ui_plugin_info.ui_extension_plugin_complete(@ext_name)
+      @ok = File.exist?(ext_plugin)
+      log.info("Not found: #{ext_plugin}") unless @ok
+      @ok
+    end
+
+    # Open a dialog to ask the user if the UI extension should be installed.
+    #
+    # @return [Boolean] true if the user wants to install the extension, false if not
+    #
+    def ask
+      # Translators: %s is a software packge name like libyui-qt-pkg15
+      msg = _("This needs package %s to be installed.") % ext_pkg
+      @ok = Popup.ContinueCancel(msg)
+    end
+
+    # Install the package for the UI extension.
+    # This also sets @ok.
+    #
+    def install
+      @ok = Package.DoInstall([ext_pkg])
+      if !@ok
+        log.error("UI extension package could not be installed: #{ext_pkg}")
+        # Translators: %s is a software packge name like libyui-qt-pkg15
+        Report.Error(_("Package %s could not be installed.") %ext_pkg)
+      end
+      @ok
+    end
+
+    # Return the package name for the UI extension.
+    #
+    # @return [String] package name
+    #
+    def ext_pkg
+      @ui_plugin_info.ui_extension_pkg(@ext_name)
+    end
+
+    # Check if the UI extension is available for this UI.
+    #
+    # @return [Boolean] true if the extension is available, false if not
+    #
+    def available_for_ui?
+      ui = @ui_plugin_info.main_ui_plugin
+      case @ext_name
+      when "pkg"
+        ["qt", "ncurses"].include?(ui)
+      when "graph"
+        ui == "qt"
+      else
+        log.error("Unknown UI extension #{@ext_name}")
+        false
+      end
+    end
+
+    # Post an error that the UI extension is not available for this UI.
+    #
+    def not_available_error
+      @ok = false
+      # Translators: %s is a UI extension name like pkg or graph
+      Report.Error(_("UI extension \"%s\" is not available for this UI.") % ext_name)
+    end
+  end
+end