user_interaction.rb

#--
# Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
# All rights reserved.
# See LICENSE.txt for permissions.
#++

##
# Module that defines the default UserInteraction.  Any class including this
# module will have access to the +ui+ method that returns the default UI.

module Gem::DefaultUserInteraction

  ##
  # The default UI is a class variable of the singleton class for this
  # module.

  @ui = nil

  ##
  # Return the default UI.

  def self.ui
    @ui ||= Gem::ConsoleUI.new
  end

  ##
  # Set the default UI.  If the default UI is never explicitly set, a simple
  # console based UserInteraction will be used automatically.

  def self.ui=(new_ui)
    @ui = new_ui
  end

  ##
  # Use +new_ui+ for the duration of +block+.

  def self.use_ui(new_ui)
    old_ui = @ui
    @ui = new_ui
    yield
  ensure
    @ui = old_ui
  end

  ##
  # See DefaultUserInteraction::ui

  def ui
    Gem::DefaultUserInteraction.ui
  end

  ##
  # See DefaultUserInteraction::ui=

  def ui=(new_ui)
    Gem::DefaultUserInteraction.ui = new_ui
  end

  ##
  # See DefaultUserInteraction::use_ui

  def use_ui(new_ui, &block)
    Gem::DefaultUserInteraction.use_ui(new_ui, &block)
  end

end

##
# Make the default UI accessible without the "ui." prefix.  Classes
# including this module may use the interaction methods on the default UI
# directly.  Classes may also reference the ui and ui= methods.
#
# Example:
#
#   class X
#     include Gem::UserInteraction
#
#     def get_answer
#       n = ask("What is the meaning of life?")
#     end
#   end

module Gem::UserInteraction

  include Gem::DefaultUserInteraction

  def alert(*args)
    ui.alert(*args)
  end

  def alert_error(*args)
    ui.alert_error(*args)
  end

  def alert_warning(*args)
    ui.alert_warning(*args)
  end

  def ask(*args)
    ui.ask(*args)
  end

  def ask_for_password(*args)
    ui.ask_for_password(*args)
  end

  def ask_yes_no(*args)
    ui.ask_yes_no(*args)
  end

  def choose_from_list(*args)
    ui.choose_from_list(*args)
  end

  def say(*args)
    ui.say(*args)
  end

  def terminate_interaction(*args)
    ui.terminate_interaction(*args)
  end
end

##
# Gem::StreamUI implements a simple stream based user interface.

class Gem::StreamUI

  attr_reader :ins, :outs, :errs

  def initialize(in_stream, out_stream, err_stream=STDERR, usetty=true)
    @ins = in_stream
    @outs = out_stream
    @errs = err_stream
    @usetty = usetty
  end

  def tty?
    if RUBY_VERSION < '1.9.3' and RUBY_PLATFORM =~ /mingw|mswin/ then
      @usetty
    else
      @usetty && @ins.tty?
    end
  end

  ##
  # Prints a formatted backtrace to the errors stream if backtraces are
  # enabled.

  def backtrace exception
    return unless Gem.configuration.backtrace

    @errs.puts "\t#{e.backtrace.join "\n\t"}"
  end

  ##
  # Choose from a list of options.  +question+ is a prompt displayed above
  # the list.  +list+ is a list of option strings.  Returns the pair
  # [option_name, option_index].

  def choose_from_list(question, list)
    @outs.puts question

    list.each_with_index do |item, index|
      @outs.puts " #{index+1}. #{item}"
    end

    @outs.print "> "
    @outs.flush

    result = @ins.gets

    return nil, nil unless result

    result = result.strip.to_i - 1
    return list[result], result
  end

  ##
  # Ask a question.  Returns a true for yes, false for no.  If not connected
  # to a tty, raises an exception if default is nil, otherwise returns
  # default.

  def ask_yes_no(question, default=nil)
    unless tty? then
      if default.nil? then
        raise Gem::OperationNotSupportedError,
              "Not connected to a tty and no default specified"
      else
        return default
      end
    end

    default_answer = case default
                     when nil
                       'yn'
                     when true
                       'Yn'
                     else
                       'yN'
                     end

    result = nil

    while result.nil? do
      result = case ask "#{question} [#{default_answer}]"
               when /^y/i then true
               when /^n/i then false
               when /^$/  then default
               else            nil
               end
    end

    return result
  end

  ##
  # Ask a question.  Returns an answer if connected to a tty, nil otherwise.

  def ask(question)
    return nil if not tty?

    @outs.print(question + "  ")
    @outs.flush

    result = @ins.gets
    result.chomp! if result
    result
  end

  if RUBY_VERSION > '1.9.2' then
    ##
    # Ask for a password. Does not echo response to terminal.

    def ask_for_password(question)
      return nil if not tty?

      require 'io/console'

      @outs.print(question + "  ")
      @outs.flush

      password = @ins.noecho {@ins.gets}
      password.chomp! if password
      password
    end
  else
    ##
    # Ask for a password. Does not echo response to terminal.

    def ask_for_password(question)
      return nil if not tty?

      @outs.print(question + "  ")
      @outs.flush

      Gem.win_platform? ? ask_for_password_on_windows : ask_for_password_on_unix
    end

    ##
    # Asks for a password that works on windows. Ripped from the Heroku gem.

    def ask_for_password_on_windows
      return nil if not tty?

      require "Win32API"
      char = nil
      password = ''

      while char = Win32API.new("crtdll", "_getch", [ ], "L").Call do
        break if char == 10 || char == 13 # received carriage return or newline
        if char == 127 || char == 8 # backspace and delete
          password.slice!(-1, 1)
        else
          password << char.chr
        end
      end

      puts
      password
    end

    ##
    # Asks for a password that works on unix

    def ask_for_password_on_unix
      return nil if not tty?

      system "stty -echo"
      password = @ins.gets
      password.chomp! if password
      system "stty echo"
      password
    end
  end

  ##
  # Display a statement.

  def say(statement="")
    @outs.puts statement
  end

  ##
  # Display an informational alert.  Will ask +question+ if it is not nil.

  def alert(statement, question=nil)
    @outs.puts "INFO:  #{statement}"
    ask(question) if question
  end

  ##
  # Display a warning in a location expected to get error messages.  Will
  # ask +question+ if it is not nil.

  def alert_warning(statement, question=nil)
    @errs.puts "WARNING:  #{statement}"
    ask(question) if question
  end

  ##
  # Display an error message in a location expected to get error messages.
  # Will ask +question+ if it is not nil.

  def alert_error(statement, question=nil)
    @errs.puts "ERROR:  #{statement}"
    ask(question) if question
  end

  ##
  # Display a debug message on the same location as error messages.

  def debug(statement)
    @errs.puts statement
  end

  ##
  # Terminate the application with exit code +status+, running any exit
  # handlers that might have been defined.

  def terminate_interaction(status = 0)
    raise Gem::SystemExitException, status
  end

  ##
  # Return a progress reporter object chosen from the current verbosity.

  def progress_reporter(*args)
    if self.kind_of?(Gem::SilentUI)
      return SilentProgressReporter.new(@outs, *args)
    end

    case Gem.configuration.verbose
    when nil, false
      SilentProgressReporter.new(@outs, *args)
    when true
      SimpleProgressReporter.new(@outs, *args)
    else
      VerboseProgressReporter.new(@outs, *args)
    end
  end

  ##
  # An absolutely silent progress reporter.

  class SilentProgressReporter
    attr_reader :count

    def initialize(out_stream, size, initial_message, terminal_message = nil)
    end

    def updated(message)
    end

    def done
    end
  end

  ##
  # A basic dotted progress reporter.

  class SimpleProgressReporter

    include Gem::DefaultUserInteraction

    attr_reader :count

    def initialize(out_stream, size, initial_message,
                   terminal_message = "complete")
      @out = out_stream
      @total = size
      @count = 0
      @terminal_message = terminal_message

      @out.puts initial_message
    end

    ##
    # Prints out a dot and ignores +message+.

    def updated(message)
      @count += 1
      @out.print "."
      @out.flush
    end

    ##
    # Prints out the terminal message.

    def done
      @out.puts "\n#{@terminal_message}"
    end

  end

  ##
  # A progress reporter that prints out messages about the current progress.

  class VerboseProgressReporter

    include Gem::DefaultUserInteraction

    attr_reader :count

    def initialize(out_stream, size, initial_message,
                   terminal_message = 'complete')
      @out = out_stream
      @total = size
      @count = 0
      @terminal_message = terminal_message

      @out.puts initial_message
    end

    ##
    # Prints out the position relative to the total and the +message+.

    def updated(message)
      @count += 1
      @out.puts "#{@count}/#{@total}: #{message}"
    end

    ##
    # Prints out the terminal message.

    def done
      @out.puts @terminal_message
    end
  end

  ##
  # Return a download reporter object chosen from the current verbosity

  def download_reporter(*args)
    if self.kind_of?(Gem::SilentUI)
      return SilentDownloadReporter.new(@outs, *args)
    end

    case Gem.configuration.verbose
    when nil, false
      SilentDownloadReporter.new(@outs, *args)
    else
      VerboseDownloadReporter.new(@outs, *args)
    end
  end

  ##
  # An absolutely silent download reporter.

  class SilentDownloadReporter
    def initialize(out_stream, *args)
    end

    def fetch(filename, filesize)
    end

    def update(current)
    end

    def done
    end
  end

  ##
  # A progress reporter that prints out messages about the current progress.

  class VerboseDownloadReporter
    attr_reader :file_name, :total_bytes, :progress

    def initialize(out_stream, *args)
      @out = out_stream
      @progress = 0
    end

    def fetch(file_name, total_bytes)
      @file_name = file_name
      @total_bytes = total_bytes.to_i
      @units = @total_bytes.zero? ? 'B' : '%'

      update_display(false)
    end

    def update(bytes)
      new_progress = if @units == 'B' then
                       bytes
                     else
                       ((bytes.to_f * 100) / total_bytes.to_f).ceil
                     end

      return if new_progress == @progress

      @progress = new_progress
      update_display
    end

    def done
      @progress = 100 if @units == '%'
      update_display(true, true)
    end

    private

    def update_display(show_progress = true, new_line = false)
      return unless @out.tty?

      if show_progress then
        @out.print "\rFetching: %s (%3d%s)" % [@file_name, @progress, @units]
      else
        @out.print "Fetching: %s" % @file_name
      end
      @out.puts if new_line
    end
  end
end

##
# Subclass of StreamUI that instantiates the user interaction using STDIN,
# STDOUT, and STDERR.

class Gem::ConsoleUI < Gem::StreamUI
  def initialize
    super STDIN, STDOUT, STDERR, true
  end
end

##
# SilentUI is a UI choice that is absolutely silent.

class Gem::SilentUI < Gem::StreamUI
  def initialize
    reader, writer = nil, nil

    begin
      reader = File.open('/dev/null', 'r')
      writer = File.open('/dev/null', 'w')
    rescue Errno::ENOENT
      reader = File.open('nul', 'r')
      writer = File.open('nul', 'w')
    end

    super reader, writer, writer, false
  end

  def download_reporter(*args)
    SilentDownloadReporter.new(@outs, *args)
  end

  def progress_reporter(*args)
    SilentProgressReporter.new(@outs, *args)
  end
end