# Copyright (c) 2007-2021 Andy Maleh
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

require 'glimmer/swt/widget_listener_proxy'
require 'glimmer/swt/custom/drawable'

module Glimmer
  module SWT
    # Proxy for org.eclipse.swt.widgets.Display
    #
    # Maintains a singleton instance since SWT only supports
    # a single active display at a time.
    #
    # Supports SWT Display's very useful asyncExec and syncExec methods
    # to support proper multi-threaded manipulation of SWT UI objects
    #
    # Invoking `#swt_display` returns the SWT Display object wrapped by this proxy
    #
    # Follows the Proxy Design Pattern
    class DisplayProxy
      include_package 'org.eclipse.swt.widgets'
      
      include Custom::Drawable

      OBSERVED_MENU_ITEMS = ['about', 'preferences']

      class << self
        # Returns singleton instance
        def instance(*args)
          if @instance.nil? || @instance.swt_display.isDisposed
            @instance = new(*args)
          end
          @instance
        end
      end

      # SWT Display object wrapped
      attr_reader :swt_display

      def initialize(*args)
        Display.app_name ||= 'Glimmer'
        @swt_display = Display.new(*args)
        @swt_display.set_data('proxy', self)
      end
      
      def content(&block)
        Glimmer::DSL::Engine.add_content(self, Glimmer::DSL::SWT::DisplayExpression.new, &block)
      end
      
      def async_exec(&block)
        @swt_display.async_exec(&block)
      end

      def sync_exec(&block)
        @swt_display.sync_exec(&block)
      end

      def timer_exec(&block)
        @swt_display.timer_exec(&block)
      end

      def method_missing(method, *args, &block)
        if can_handle_observation_request?(method)
          handle_observation_request(method, &block)
        else
          swt_display.send(method, *args, &block)
        end
      rescue => e
        Glimmer::Config.logger.debug {"Neither DisplayProxy nor #{swt_display.class.name} can handle the method ##{method}"}
        super
      end
      
      def respond_to?(method, *args, &block)
        super ||
          can_handle_observation_request?(method) ||
          swt_display.respond_to?(method, *args, &block)
      end

      def can_handle_observation_request?(observation_request)
        observation_request = observation_request.to_s
        if observation_request.start_with?('on_swt_')
          constant_name = observation_request.sub(/^on_swt_/, '')
          SWTProxy.has_constant?(constant_name)
        elsif observation_request.start_with?('on_')
          event_name = observation_request.sub(/^on_/, '')
          OBSERVED_MENU_ITEMS.include?(event_name)
        else
          false
        end
      end

      def handle_observation_request(observation_request, &block)
        observation_request = observation_request.to_s
        if observation_request.start_with?('on_swt_')
          constant_name = observation_request.sub(/^on_swt_/, '')
          add_swt_event_listener(constant_name, &block)
        elsif observation_request.start_with?('on_')
          event_name = observation_request.sub(/^on_/, '')
          if OBSERVED_MENU_ITEMS.include?(event_name)
            if OS.mac?
              system_menu = swt_display.getSystemMenu
              menu_item = system_menu.getItems.find {|menu_item| menu_item.getID == SWTProxy["ID_#{event_name.upcase}"]}
              menu_item.addListener(SWTProxy[:Selection], &block)
            end
          end
        end
      end

      def add_swt_event_listener(swt_constant, &block)
        event_type = SWTProxy[swt_constant]
        @swt_display.addFilter(event_type, &block)
        #WidgetListenerProxy.new(@swt_display.getListeners(event_type).last)
      end
    end
  end
end