#!/usr/bin/env python3
import subprocess

import i3ipc
import psutil
import pulsectl


def main():
    i3 = i3ipc.Connection()
    window = i3.get_tree().find_focused()
    cmd = ['xprop', '-id', str(window.window), '_NET_WM_PID']
    o = subprocess.run(cmd, encoding='utf-8', capture_output=True)
    # _NET_WM_PID(CARDINAL) = 418472
    pid = int(o.stdout.strip().split(' = ')[1])

    pulse = pulsectl.Pulse('Focused sink switcher')
    sink_input_by_pid = {}
    for i in pulse.sink_input_list():
        sink_pid = int(i.proplist['application.process.id'])
        sink_input_by_pid[sink_pid] = i

    if pid in sink_input_by_pid:
        sink_input = sink_input_by_pid[pid]
    else:
        # try the childprocesses of our process, because this might be a
        # terminal having started an mpv or something
        p = psutil.Process(pid)
        for child in p.children(recursive=True):
            if child.pid in sink_input_by_pid:
                sink_input = sink_input_by_pid[child.pid]
                break
        else:
            msg = 'Did not find a pulse client for pid {} or its children.'
            raise RuntimeError(msg.format(pid))

    sink_index_list = [s.index for s in pulse.sink_list()]
    old_sink = sink_input.sink
    old_sink_index = sink_index_list.index(old_sink)
    new_sink_index = sink_index_list[(old_sink_index + 1) % len(sink_index_list)]

    pulse.sink_input_move(sink_input.index, new_sink_index)


if __name__ == '__main__':
    main()