Ubuntu BT speakers/headphones connection script.

mad_connect_headphones.rb

#!/usr/bin/env ruby

require 'open3'
require 'io/wait'

# :readline will block if there is no input available, while :readX will raise an error; in order
# to solve this problem easily, the 'io/wait' library makes `IO#ready?` available.
#
def read_available_io(io)
  buffer = ''
  buffer << io.readchar while io.ready?
  buffer
end

def connect_bt(bt_id, btctl_in, btctl_out)
  loop do
    btctl_in.puts("connect #{ bt_id }")

    while true
      output = read_available_io(btctl_out)

      puts output if output != ''

      case output
      when /Connection successful/
        puts
        return
      when /Failed to connect/
        break
      else
        sleep 0.5
      end
    end
  end
end

def disconnect_bt(bt_id, btctl_in, btctl_out)
  loop do
    btctl_in.puts("disconnect #{ bt_id }")

    while true
      output = read_available_io(btctl_out)

      puts output if output != ''

      # Disconnection will always be successful, when the device is available.
      #
      case output
      when /Successful disconnected/
        puts
        return
      when /Device [0-9A-F:] not available/
        raise "Dafuq!!"
      else
        sleep 0.5
      end
    end
  end
end

def set_pa_card_profile(card, profile)
  puts "Setting PA card profile: #{ profile }"

  Open3.popen3("pactl set-card-profile #{ card } #{ profile }") do |_, _, stderr, wait_thread|
    if ! wait_thread.value.success?
      puts stderr.readlines.join
      exit
    end
  end

  puts
end

def mad_connect_headphones(bt_id, pa_card_name)
  Open3.popen3('bluetoothctl') do |stdin, stdout, _, _|
    puts read_available_io(stdout)

    connect_bt(bt_id, stdin, stdout)

    set_pa_card_profile(pa_card_name, 'off')

    disconnect_bt(bt_id, stdin, stdout)
    connect_bt(bt_id, stdin, stdout)

    set_pa_card_profile(pa_card_name, 'a2dp_sink')
  end
end

# Use `pactl list cards` for informations about the cards.
#
BLUETOOTH_ID = 'set me!'
PULSEAUDIO_CARD_NAME = 'set me!'

if __FILE__ == $0
  mad_connect_headphones(BLUETOOTH_ID, PULSEAUDIO_CARD_NAME)
end