class Reline::LineEditor

def rerender
  return if @line.nil?
  if @menu_info
    scroll_down(@highest_in_all - @first_line_started_from)
    @rerender_all = true
  end
  if @menu_info
    show_menu
    @menu_info = nil
  end
  prompt, prompt_width, prompt_list = check_multiline_prompt(whole_lines)
  if @cleared
    clear_screen_buffer(prompt, prompt_list, prompt_width)
    @cleared = false
    return
  end
  if @is_multiline and finished? and @scroll_partial_screen
    # Re-output all code higher than the screen when finished.
    Reline::IOGate.move_cursor_up(@first_line_started_from + @started_from - @scroll_partial_screen)
    Reline::IOGate.move_cursor_column(0)
    @scroll_partial_screen = nil
    new_lines = whole_lines
    prompt, prompt_width, prompt_list = check_multiline_prompt(new_lines)
    modify_lines(new_lines).each_with_index do |line, index|
      @output.write "#{prompt_list ? prompt_list[index] : prompt}#{line}\r\n"
      Reline::IOGate.erase_after_cursor
    end
    @output.flush
    clear_dialog
    return
  end
  new_highest_in_this = calculate_height_by_width(prompt_width + calculate_width(@line.nil? ? '' : @line))
  rendered = false
  if @add_newline_to_end_of_buffer
    clear_dialog_with_content
    rerender_added_newline(prompt, prompt_width, prompt_list)
    @add_newline_to_end_of_buffer = false
  else
    if @just_cursor_moving and not @rerender_all
      clear_dialog_with_content
      rendered = just_move_cursor
      @just_cursor_moving = false
      return
    elsif @previous_line_index or new_highest_in_this != @highest_in_this
      clear_dialog_with_content
      rerender_changed_current_line
      @previous_line_index = nil
      rendered = true
    elsif @rerender_all
      rerender_all_lines
      @rerender_all = false
      rendered = true
    else
    end
  end
  if @is_multiline
    if finished?
      # Always rerender on finish because output_modifier_proc may return a different output.
      new_lines = whole_lines
      line = modify_lines(new_lines)[@line_index]
      clear_dialog
      prompt, prompt_width, prompt_list = check_multiline_prompt(new_lines)
      render_partial(prompt, prompt_width, line, @first_line_started_from)
      move_cursor_down(@highest_in_all - (@first_line_started_from + @highest_in_this - 1) - 1)
      scroll_down(1)
      Reline::IOGate.move_cursor_column(0)
      Reline::IOGate.erase_after_cursor
    else
      if not rendered and not @in_pasting
        line = modify_lines(whole_lines)[@line_index]
        prompt, prompt_width, prompt_list = check_multiline_prompt(whole_lines)
        render_partial(prompt, prompt_width, line, @first_line_started_from)
      end
      render_dialog((prompt_width + @cursor) % @screen_size.last)
    end
    @buffer_of_lines[@line_index] = @line
    @rest_height = 0 if @scroll_partial_screen
  else
    line = modify_lines(whole_lines)[@line_index]
    render_partial(prompt, prompt_width, line, 0)
    if finished?
      scroll_down(1)
      Reline::IOGate.move_cursor_column(0)
      Reline::IOGate.erase_after_cursor
    end
  end
end