user_interaction.rb

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

begin
  require 'io/console'
rescue LoadError
end

##
# 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

##
# UserInteraction allows RubyGems to interact with the user through standard
# methods that can be replaced with more-specific UI methods for different
# displays.
#
# Since UserInteraction dispatches to a concrete UI class you may need to
# reference other classes for specific behavior such as Gem::ConsoleUI or
# Gem::SilentUI.
#
# 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

  ##
  # Displays an alert +statement+.  Asks a +question+ if given.

  def alert statement, question = nil
    ui.alert statement, question
  end

  ##
  # Displays an error +statement+ to the error output location.  Asks a
  # +question+ if given.

  def alert_error statement, question = nil
    ui.alert_error statement, question
  end

  ##
  # Displays a warning +statement+ to the warning output location.  Asks a
  # +question+ if given.

  def alert_warning statement, question = nil
    ui.alert_warning statement, question
  end

  ##
  # Asks a +question+ and returns the answer.

  def ask question
    ui.ask question
  end

  ##
  # Asks for a password with a +prompt+

  def ask_for_password prompt
    ui.ask_for_password prompt
  end

  ##
  # Asks a yes or no +question+.  Returns true for yes, false for no.

  def ask_yes_no question, default = nil
    ui.ask_yes_no question, default
  end

  ##
  # Asks the user to answer +question+ with an answer from the given +list+.

  def choose_from_list question, list
    ui.choose_from_list question, list
  end

  ##
  # Displays the given +statement+ on the standard output (or equivalent).

  def say statement = ''
    ui.say statement
  end

  ##
  # Terminates the RubyGems process with the given +exit_code+

  def terminate_interaction exit_code = 0
    ui.terminate_interaction exit_code
  end

  ##
  # Calls +say+ with +msg+ or the results of the block if really_verbose
  # is true.

  def verbose msg = nil
    say(msg || yield) if Gem.configuration.really_verbose
  end
end

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

class Gem::StreamUI

  ##
  # The input stream

  attr_reader :ins

  ##
  # The output stream

  attr_reader :outs

  ##
  # The error stream

  attr_reader :errs

  ##
  # Creates a new StreamUI wrapping +in_stream+ for user input, +out_stream+
  # for standard output, +err_stream+ for error output.  If +usetty+ is true
  # then special operations (like asking for passwords) will use the TTY
  # commands to disable character echo.

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

  ##
  # Returns true if TTY methods should be used on this StreamUI.

  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#{exception.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

  ##
  # 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

    password = _gets_noecho
    @outs.puts
    password.chomp! if password
    password
  end

  if IO.method_defined?(:noecho) then
    def _gets_noecho
      @ins.noecho {@ins.gets}
    end
  elsif Gem.win_platform?
    def _gets_noecho
      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
      password
    end
  else
    def _gets_noecho
      system "stty -echo"
      begin
        @ins.gets
      ensure
        system "stty echo"
      end
    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 on stderr.  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

    ##
    # The count of items is never updated for the silent progress reporter.

    attr_reader :count

    ##
    # Creates a silent progress reporter that ignores all input arguments.

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

    ##
    # Does not print +message+ when updated as this object has taken a vow of
    # silence.

    def updated(message)
    end

    ##
    # Does not print anything when complete as this object has taken a vow of
    # silence.

    def done
    end
  end

  ##
  # A basic dotted progress reporter.

  class SimpleProgressReporter

    include Gem::DefaultUserInteraction

    ##
    # The number of progress items counted so far.

    attr_reader :count

    ##
    # Creates a new progress reporter that will write to +out_stream+ for
    # +size+ items.  Shows the given +initial_message+ when progress starts
    # and the +terminal_message+ when it is complete.

    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

    ##
    # The number of progress items counted so far.

    attr_reader :count

    ##
    # Creates a new progress reporter that will write to +out_stream+ for
    # +size+ items.  Shows the given +initial_message+ when progress starts
    # and the +terminal_message+ when it is complete.

    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

    ##
    # The silent download reporter ignores all arguments

    def initialize(out_stream, *args)
    end

    ##
    # The silent download reporter does not display +filename+ or care about
    # +filesize+ because it is silent.

    def fetch(filename, filesize)
    end

    ##
    # Nothing can update the silent download reporter.

    def update(current)
    end

    ##
    # The silent download reporter won't tell you when the download is done.
    # Because it is silent.

    def done
    end
  end

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

  class VerboseDownloadReporter

    ##
    # The current file name being displayed

    attr_reader :file_name

    ##
    # The total bytes in the file

    attr_reader :total_bytes

    ##
    # The current progress (0 to 100)

    attr_reader :progress

    ##
    # Creates a new verbose download reporter that will display on
    # +out_stream+.  The other arguments are ignored.

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

    ##
    # Tells the download reporter that the +file_name+ is being fetched and
    # contains +total_bytes+.

    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

    ##
    # Updates the verbose download reporter for the given number of +bytes+.

    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

    ##
    # Indicates the download is complete.

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

    private

    def update_display(show_progress = true, new_line = false) # :nodoc:
      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

  ##
  # The Console UI has no arguments as it defaults to reading input from
  # stdin, output to stdout and warnings or errors to stderr.

  def initialize
    super STDIN, STDOUT, STDERR, true
  end
end

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

class Gem::SilentUI < Gem::StreamUI

  ##
  # The SilentUI has no arguments as it does not use any stream.

  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) # :nodoc:
    SilentDownloadReporter.new(@outs, *args)
  end

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