#!/usr/bin/env python3

import sys

from pulsectl import Pulse, PulseLoopStop


def callback(ev):
    if ev.index == source_index:
        raise PulseLoopStop


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


def get_default_source_idx():
    default_source_name = pulse.server_info().default_source_name
    try:
        source_index = next(index for index, source in sources.items()
                            if source.name == default_source_name)
        return source_index
    except StopIteration:
        raise StopIteration("No default source was found.")


try:
    with Pulse() as pulse:
        sources = {s.index: s for s in pulse.source_list()}

        if len(sys.argv) > 1:
            # Source index from command line argument if provided
            source_index = int(sys.argv[1])
            if source_index not in sources:
                raise KeyError(
                    f"Source index {source_index} not found in list of sources."
                )
        else:
            # Automatic determination of default source otherwise
            source_index = get_default_source_idx()

        pulse.event_mask_set('source')
        pulse.event_callback_set(callback)
        last_value, last_mute = current_status(sources[source_index])

        while True:
            pulse.event_listen()
            sources = {s.index: s for s in pulse.source_list()}
            value, mute = current_status(sources[source_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)