# frozen_string_literal: true

module Vedeu

  module Interfaces

    # Clear the named interface.
    #
    # @api private
    #
    class Clear

      include Vedeu::Common

      class << self

        # {include:file:docs/dsl/by_method/clear_by_name.md}
        # @return [Array<Array<Vedeu::Cells::Char>>]
        # @see #initialize
        def render(name = Vedeu.focus)
          name || Vedeu.focus

          new(name).render
        end
        alias clear_by_name render
        alias by_name render

      end # Eigenclass

      # Return a new instance of Vedeu::Interfaces::Clear.
      #
      # @macro param_name
      # @return [Vedeu::Interfaces::Clear]
      def initialize(name = Vedeu.focus)
        @name = present?(name) ? name : Vedeu.focus
      end

      # @return [Array<Array<Vedeu::Cells::Char>>]
      def render
        Vedeu.render_output(output) if Vedeu.ready?
      end

      protected

      # @!attribute [r] name
      # @macro return_name
      attr_reader :name

      private

      # @return [String] A string of blank characters.
      def chars
        @_chars ||= (' ' * width)
      end

      # @return [Vedeu::Colours::Colour]
      def colour
        @_colour ||= interface.colour
      end

      # @macro geometry_by_name
      def geometry
        @_geometry ||= Vedeu.geometries.by_name(name)
      end

      # @return [Fixnum]
      def height
        @_height ||= geometry.height
      end

      # @macro interface_by_name
      def interface
        Vedeu.interfaces.by_name(name)
      end

      # For each visible line of the interface, set the foreground and
      # background colours to those specified when the interface was
      # defined, then starting write space characters over the area
      # which the interface occupies.
      #
      # @return [Array<Array<Vedeu::Cells::Char>>]
      def output
        Vedeu.timer("Clearing interface: '#{name}'") do
          @_clear ||= Array.new(height) do |iy|
            Array.new(width) do |ix|
              Vedeu::Cells::Clear.new(output_attributes(iy, ix))
            end
          end
        end
      end

      # @param iy [Fixnum]
      # @param ix [Fixnum]
      # @return [Hash<Symbol => ]
      def output_attributes(iy, ix)
        {
          colour:   colour,
          name:     name,
          position: Vedeu::Geometries::Position.new((y + iy), (x + ix)),
        }
      end

      # @return [Fixnum]
      def width
        @_width ||= geometry.width
      end

      # @return [Fixnum]
      def y
        @_y ||= geometry.y
      end

      # @return [Fixnum]
      def x
        @_x ||= geometry.x
      end

    end # Clear

  end # Interfaces

  # @api public
  # @!method clear_by_name
  #   @see Vedeu::Interfaces::Clear.clear_by_name
  def_delegators Vedeu::Interfaces::Clear,
                 :clear_by_name

end # Vedeu