Asterisk music on hold in any conference room

adhearsion-asterisk-music-on-hold.rb

# play music on hold (MP3 or other) as a second conference "participant", 
# then disconnect (stop the music) when a real second participant joins.
#
# NOTE: this is a reference example.  It hasn't been tested and 
# may not run exactly as-is.

class ConferenceDirectory
  def initialize
    @rooms = {}
  end

  def join_room(room, call)
    @rooms[room] ||= ConferenceRoom.new(room)
    @rooms[room].join(call)
  end
end


class ConferenceRoom
  def initialize(name)
    @name = name
    @participants = []
  end

  def join(call)
    # this method will be called twice: once with music_on_room defined,
    # where we'll be playing music, and once without it, where 
    # we'll be joining the conference.
    if call.call.variables[:music_for_room]
      if call.call.channel == @music_generation_channel
        loop do
          call.playback 'pretty-music'
        end
      else
        @music_playback_channel = call.call.channel
        
        call.execute 'Conference', @name
        call.hangup
      end
    else
      @participants << call

      call.execute 'Conference', @name

      manage_music
    end
  end

  def part(call)
    @participants.delete(call)

    manage_music
  end

  def manage_music
    # only play as long as we're keeping someone company
    if @participants.length == 1
      start_music
    else
      stop_music
    end
  end

  def start_music(call)
    # place a call to this AGI (channel parameter), and when it answers, make the call get 
    # handled by this AGI (extension, context, priority, and variable).
    # this AGI will get hit twice -- once with a "music_for_room" variable, and once
    # without.  could use 2 AGIs if you wanted: one that joins the room, and one that 
    # plays a music loop.
    response = manager.originate :channel => "Local/#{call.extension}@#{call.context}",
      :extension => call.extension, :context => call.context, :priority => 1,
      'Variable' => "music_for_room=#{@name}"
    
    @music_generation_channel = response['Channel']
  end
  
  def stop_music
    if @music_playback_channel
      manager.hangup @music_playback_channel
    end
    
    if @music_generation_channel
      manager.hangup @music_generation_channel
    end
  end
  
  private
  def manager
    Adhearsion::VoIP::Asterisk.manager_interface
  end
end