#!/usr/bin/env python3
"""Snapshot/restore mixer-managed files and service states, not apt packages."""
import json
import os
from pathlib import Path
import shutil
import subprocess
import sys

UNITS = ['shairport-sync', 'nqptp', 'bluealsa', 'bluealsa-aplay',
         'radxa-bt-output', 'radxa-bose-output', 'radxa-mixer-web', 'avahi-daemon', 'bluetooth']
PATHS = [
    '/etc/systemd/system/radxa-mixer-web.service',
    '/etc/dbus-1/system.d/shairport-sync-dbus.conf',
    '/usr/local/lib/radxa-mixer/input_controls.py',
    '/usr/local/lib/radxa-mixer/web_server.py',
    '/usr/local/lib/radxa-mixer/web/index.html',
    '/usr/local/lib/radxa-mixer/web/app.js',
    '/usr/local/lib/radxa-mixer/web/style.css',
    '/etc/asound.conf', '/etc/shairport-sync.conf',
    '/etc/radxa-audio/mixer.json', '/etc/radxa-audio/asound-dac.conf',
    '/etc/radxa-audio/input-memory.json',
    '/etc/radxa-audio/asound-bluetooth.conf',
    '/etc/systemd/system/shairport-sync.service', '/etc/systemd/system/nqptp.service',
    '/etc/systemd/system/bluealsa.service.d/10-radxa-sink.conf',
    '/etc/systemd/system/bluealsa-aplay.service.d/10-radxa-mixer.conf',
    '/etc/systemd/system/radxa-bt-output.service',
    '/etc/modules-load.d/radxa-audio-loopback.conf',
    '/etc/modprobe.d/radxa-audio-loopback.conf',
    '/etc/modprobe.d/90-radxa-airplay-wifi.conf',
    '/usr/local/bin/shairport-sync', '/usr/local/bin/nqptp',
    '/usr/local/bin/radxa-audio', '/usr/local/bin/radxa-audio-output',
]


def ctl(*args):
    return subprocess.run(['systemctl', *args], stdout=subprocess.PIPE,
                          stderr=subprocess.STDOUT, text=True)


def snapshot(directory):
    directory.mkdir(parents=True, exist_ok=False, mode=0o700)
    files = {}
    for name in PATHS:
        path = Path(name)
        files[name] = os.path.lexists(path)
        if files[name]:
            target = directory / 'files' / name.lstrip('/')
            target.parent.mkdir(parents=True, exist_ok=True)
            shutil.copy2(path, target, follow_symlinks=False)
    states = {u: {'active': ctl('is-active', '--quiet', u).returncode == 0,
                  'enabled': ctl('is-enabled', '--quiet', u).returncode == 0} for u in UNITS}
    (directory / 'manifest.json').write_text(json.dumps({'files': files, 'units': states}, indent=2))


def restore(directory):
    manifest = json.loads((directory / 'manifest.json').read_text())
    # Only restore allowlisted paths from our own snapshot.
    if not set(manifest['files']).issubset(PATHS) or not set(manifest['units']).issubset(UNITS):
        raise ValueError('알 수 없는 백업 형식입니다.')
    for unit in UNITS[:7]: ctl('stop', unit)
    for name, existed in manifest['files'].items():
        target = Path(name)
        if existed:
            target.parent.mkdir(parents=True, exist_ok=True)
            target.unlink(missing_ok=True)
            shutil.copy2(directory / 'files' / name.lstrip('/'), target, follow_symlinks=False)
        else:
            target.unlink(missing_ok=True)
    ctl('daemon-reload')
    for unit in UNITS:
        state = manifest['units'].get(unit, {'active': False, 'enabled': False})
        ctl('enable' if state['enabled'] else 'disable', unit)
    # Bluetooth and Avahi may have been started by apt during installation.
    for unit in reversed(UNITS):
        state = manifest['units'].get(unit, {'active': False, 'enabled': False})
        result = ctl('restart' if state['active'] else 'stop', unit)
        if state['active'] and result.returncode:
            print(result.stdout, file=sys.stderr)
            raise ValueError('서비스 복원에 실패했습니다: ' + unit)
    print('복구 완료:', directory)
    print('apt로 설치한 의존 패키지는 유지합니다. 블루투스 페어링 기록은 삭제하지 않습니다.')


if __name__ == '__main__':
    if os.geteuid() != 0: sys.exit('sudo로 실행해 주세요.')
    if len(sys.argv) != 3 or sys.argv[1] not in ('save', 'restore'):
        sys.exit('Usage: backup.py save|restore DIRECTORY')
    if sys.argv[1] == 'save': snapshot(Path(sys.argv[2]))
    else: restore(Path(sys.argv[2]))