require_relative '../parent'
require_relative 'g_swt'

module Glimmer
  module SWT
    class GLayout
      include_package 'org.eclipse.swt.layout'

      include Parent

      attr_reader :composite
      attr_reader :layout

      class << self
        include_package 'org.eclipse.swt.layout'

        def layout_exists?(underscored_layout_name)
          begin
            swt_layout_class_for(underscored_layout_name)
            true
          rescue NameError => e
            false
          end
        end

        # This supports layouts in and out of basic SWT
        def swt_layout_class_for(underscored_layout_name)
          swt_layout_name = underscored_layout_name.camelcase(:upper)
          swt_layout_class = eval(swt_layout_name)
          unless swt_layout_class.ancestors.include?(org.eclipse.swt.widgets.Layout)
            raise NameError, "Class #{swt_layout_class} matching #{underscored_layout_name} is not a subclass of org.eclipse.swt.widgets.Layout"
          end
          swt_layout_class
        rescue => e
          Glimmer.logger.debug "#{e.message}\n#{e.backtrace.join("\n")}"
          raise e
        end
      end

      def initialize(underscored_layout_name, composite, args)
        @underscored_layout_name = underscored_layout_name
        @composite = composite
        args = GSWT.constantify_args(args)
        @layout = self.class.swt_layout_class_for(underscored_layout_name).new(*args)
        @composite.setLayout(@layout)
      end

      def process_block(block)
        block.call(@layout)
      end

      def has_attribute?(attribute_name, *args)
        @layout.respond_to?(attribute_setter(attribute_name), args)
      end

      def set_attribute(attribute_name, *args)
        apply_property_type_converters(attribute_name, args)
        @layout.send(attribute_setter(attribute_name), *args)
      end

      def apply_property_type_converters(attribute_name, args)
        if args.count == 1 && GSWT.has_constant?(args.first)
          args[0] = GSWT.constant(args.first)
        end
      end

      def attribute_setter(attribute_name)
        "#{attribute_name.to_s.camelcase(:lower)}="
      end
    end
  end
end