radio_manager.py

# Standard library imports
import os
import subprocess
import logging

# Third party imports
from gi.repository import GLib
from pydbus import SystemBus
import yaml

# Local application imports
import lib.utils

# Callback then runs when the speakler connects/disconnects


def on_state_change(sender, message, other):
    # sender <-- string
    # message <-- dictionary with properties that changed and values
    # other <-- list (empty in this app)
    if sender == 'org.bluez.Device1':
        # check how many instance of radio app are running
        if message['Connected']:
            radios.refresh()
            logging.debug("Speaker connection detected.")
            logging.debug("Radio count = " + str(radios.count))
            if radios.count == 0:
                logging.debug("Starting Radio")
                subprocess.call(CONFIG["radio_start_script"])
            elif radios.count > 1:
                radios.leaveOne()
        else:
            logging.debug("Speaker disconnection detected.")
            radios.refresh()
            if radios.count > 0:
                radios.killAll()
                logging.debug("Stopping Radio.")
            else:
                logging.debug("No Radios found.")


# Read the config file, set up logging
with open(os.path.join(os.path.abspath(os.path.dirname(__file__)),
                       'radio_config.yaml'), 'r') as ymlfile:
    CONFIG = yaml.safe_load(ymlfile)
logging.basicConfig(level=CONFIG["log_level"])
logging.info("Radio Manager has started.")
# Setup Management of Pianobar
radios = lib.utils.findProcByName("pianobar")
radio_start_script = CONFIG["radio_start_script"]


# Subscribe to dbus signal and start loop
bus = SystemBus()
speaker = bus.get('org.bluez',
                  '/org/bluez/hci0/dev_' +
                  CONFIG["speaker_address"].replace(":", "_"))

speaker.onPropertiesChanged = on_state_change
loop = GLib.MainLoop()
loop.run()  # blocks until callback comes in