Mini Shell

# encoding: utf-8
#  Phusion Passenger - https://www.phusionpassenger.com/
#  Copyright (c) 2013-2017 Phusion Holding B.V.
#
#  "Passenger", "Phusion Passenger" and "Union Station" are registered
#  trademarks of Phusion Holding B.V.
#
#  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.

module PhusionPassenger
  module Utils

    class TerminalChoiceMenu
      class Choice
        attr_reader :name
        attr_accessor :checked

        alias checked? checked

        def self.create(choice)
          if choice.is_a?(Choice)
            return choice
          else
            return Choice.new(choice)
          end
        end

        def initialize(name, checked = false)
          @name = name
          @checked = checked
        end

        def toggle!
          @checked = !@checked
        end
      end

      def initialize(choices, mode = :multiple_choice)
        @choices = choices.map { |choice| Choice.create(choice) }
        @mode    = mode
        @pointer = 0
        @index   = index_choices
      end

      def display_choices
        display(render_to_string)
      end

      def query
        if STDIN.tty?
          done = false
          begin
            raw_no_echo_mode
            hide_cursor
            while !done
              display_choices
              done = process_input
              clear_screen if !done
            end
            if @mode == :single_choice
              [@pointer, @choices[@pointer].name]
            else
              nil
            end
          ensure
            restore_mode
            show_cursor
            puts
          end
        else
          display_choices
          puts
          nil
        end
      end

      def [](name)
        return @index[name]
      end

      def selected_choices
        @choices.find_all{ |c| c.checked? }.map{ |c| c.name }
      end

    private
      JRUBY = defined?(RUBY_ENGINE) && RUBY_ENGINE == 'jruby'

      def index_choices
        index = {}
        @choices.each do |choice|
          index[choice.name] = choice
        end
        return index
      end

      def process_input
        case getchar(STDIN)
        when "\x1b"
          process_cursor_move
          false
        when " "
          if @mode == :multiple_choice
            process_toggle
          end
          false
        when "!"
          process_disable_utf8
          false
        when "\r"
          true
        else
          false
        end
      end

      def process_cursor_move
        if getchar(STDIN) == "["
          case getchar(STDIN)
          when "A" # up
            @pointer = [@pointer - 1, 0].max
          when "B" # down
            @pointer = [@pointer + 1, @choices.size - 1].min
          end
        end
      end

      def process_toggle
        @choices[@pointer].toggle!
      end

      def process_disable_utf8
        ENV['UTF8_MENUS'] = '0'
      end

      def render_to_string
        str = ""
        @choices.each_with_index do |choice, i|
          pointer = render_pointer(i)
          checkbox = render_checkbox(choice.checked)
          str << " #{pointer} #{checkbox}  #{choice.name}\r\n"
        end
        str.chomp!
        str
      end

      def render_pointer(index)
        @pointer == index ? maybe_utf8("‣", ">") : " "
      end

      def render_checkbox(checked)
        if @mode == :multiple_choice
          if checked
            maybe_utf8("⬢", "(*)")
          else
            maybe_utf8("⬡", "( )")
          end
        else
          nil
        end
      end

      def display(str)
        STDOUT.write(str)
        STDOUT.flush
      end

      def clear_screen
        number_of_lines = render_to_string.split("\n").size
        display("\r")
        (number_of_lines - 1).times do
          display(move_up)
        end
      end

      def maybe_utf8(utf8, plain)
        if ENV['UTF8_MENUS'] == '0'
          return plain
        else
          return utf8
        end
      end

      def hide_cursor
        display("\x1b[?25l")
      end

      def show_cursor
        display("\x1b[?25h")
      end

      def move_up
        return "\x1b[0A"
      end

      def getchar(io)
        char = io.getc
        char = char.chr if char.is_a?(Integer)
        return char
      end

      if JRUBY
        require 'java'
        require 'readline'
        java_import 'jline.console.ConsoleReader'

        def raw_no_echo_mode
          input = STDIN.to_inputstream
          output = STDOUT.to_outputstream
          @console = ConsoleReader.new(input, output)
          @console.set_history_enabled(false)
          @console.set_bell_enabled(true)
          @console.set_pagination_enabled(false)
          @terminal_state = @console.getEchoCharacter
          @console.setEchoCharacter(0)
        end

        def restore_mode
          @console.setEchoCharacter(@terminal_state)
          @console.get_terminal.restore
        end
      else
        def raw_no_echo_mode
          @terminal_state = `stty -g`
          system("stty raw -echo -icanon isig")
        end

        def restore_mode
          system("stty #{@terminal_state}")
        end
      end
    end

  end # module Utils
end # module PhusionPassenger