#!/usr/bin/env python3

from pulsectl import Pulse, PulseLoopStop
import sys

with Pulse() as pulse:
  while True:
    def callback(ev):
      if ev.index == sink_index: raise PulseLoopStop

    def current_status(sink):
      return round(sink.volume.value_flat * 100), sink.mute == 1

    def get_default_sink_idx():
      default_sink_name = pulse.server_info().default_sink_name
      try:
        sink_index = next(index for index,sink in sinks.items() if sink.name == default_sink_name)
        return sink_index
      except StopIteration: raise StopIteration("No default sink was found.")

    try:
      sinks = {s.index:s for s in pulse.sink_list()}
      if len(sys.argv) > 1:
        # Sink index from command line argument if provided
        sink_index = int(sys.argv[1])
        if not sink_index in sinks:
          raise KeyError(f"Sink index {sink_index} not found in list of sinks.")
      else:
        # Automatic determination of default sink otherwise
        sink_index = get_default_sink_idx()

      pulse.event_mask_set('sink')
      pulse.event_callback_set(callback)
      last_value, last_mute = current_status(sinks[sink_index])

      while True:
        pulse.event_listen()
        sinks = {s.index:s for s in pulse.sink_list()}
        value, mute = current_status(sinks[sink_index])
        if value != last_value or mute != last_mute:
          print(str(value) + ('!' if mute else ''))
          last_value, last_mute = value, mute
        sys.stdout.flush()

    except Exception as e:
      print(f"ERROR: {e}", file=sys.stderr)