#!/usr/bin/env python3
from pulsectl import Pulse, PulseLoopStop
import sys

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

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

    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
            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)
            except StopIteration:
                raise StopIteration("No default sink was found.")

        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)
