conjurer/navidrome_bridge/bridge.py

#!/usr/bin/env python3
"""Navidrome -> betoniarka request bridge.

EXTERNAL COMPONENT. This does not import anything from Conjurer and does not
talk to the Discord bot ("Kondziu") or its API. It speaks two protocols only:

    Navidrome  <--(Subsonic API, read-only + optional unstar)--  bridge
    betoniarka <--(/request_radio_file, or the request playlist)--  bridge

The one-click trigger is Navidrome's own star/love button: star the track you
are listening to and it lands in the radio's request queue. Navidrome's plugin
system cannot add a button to its UI (see README), so the built-in star is used
as the trigger instead - which has the pleasant side effect of working in every
Subsonic client, phone apps included.

Both sides index the same mp3 files under different mount points, so every path
is translated between the two roots before being handed to the radio.
"""
import hashlib
import json
import logging
import os
import posixpath
import re
import secrets
import sys
import time
from pathlib import Path

import requests

LOG = logging.getLogger("navidrome-bridge")


def _env(name: str, default: str = "") -> str:
    return os.getenv(name, default)


def _env_bool(name: str, default: bool = False) -> bool:
    raw = os.getenv(name)
    if raw is None:
        return default
    return raw.strip().lower() in ("1", "true", "yes", "on")


# ----------------------------------------------------------------- config
NAVIDROME_URL = _env("NAVIDROME_URL", "http://localhost:4533").rstrip("/")
NAVIDROME_USER = _env("NAVIDROME_USER")
NAVIDROME_PASSWORD = _env("NAVIDROME_PASSWORD")

# The same library seen from two places. Navidrome reports a path; whatever
# prefix it carries is swapped for the radio's mount point.
NAVIDROME_LIBRARY_ROOT = _env("NAVIDROME_LIBRARY_ROOT", "/music").rstrip("/")
BETONIARKA_LIBRARY_ROOT = _env("BETONIARKA_LIBRARY_ROOT", "/srv/betoniarka/music").rstrip("/")

BETONIARKA_URL = _env("BETONIARKA_URL", "http://localhost:5005").rstrip("/")
CONJURER_API_KEY = _env("CONJURER_API_KEY")

# "api"      - POST /request_radio_file (works over the network; the radio
#              re-finds the track by keywords, so it is a fuzzy match)
# "playlist" - append the exact translated path to the request playlist
#              (exact, but needs the radio's data dir reachable here)
MODE = _env("BRIDGE_MODE", "api").strip().lower()
REQUEST_PLAYLIST = Path(_env("BETONIARKA_REQUEST_PLAYLIST", "/srv/betoniarka/data/request.playlist"))

POLL_SECONDS = int(_env("BRIDGE_POLL_SECONDS", "15"))
STATE_FILE = Path(_env("BRIDGE_STATE_FILE", "/data/queued.json"))
# Un-star after queueing, turning the heart into a fire-and-forget "send to
# radio" button. Off by default: most people use stars as actual favourites.
UNSTAR_AFTER_QUEUE = _env_bool("BRIDGE_UNSTAR_AFTER_QUEUE", False)
# Only act on tracks starred from now on, so enabling the bridge does not
# dump a lifetime of favourites into the radio on first run.
SKIP_EXISTING_ON_FIRST_RUN = _env_bool("BRIDGE_SKIP_EXISTING_ON_FIRST_RUN", True)
DRY_RUN = _env_bool("BRIDGE_DRY_RUN", False)

SUBSONIC_CLIENT = "conjurer-navidrome-bridge"
SUBSONIC_VERSION = "1.16.1"
HTTP_TIMEOUT = 30


# ------------------------------------------------------------- subsonic io
def _auth_params() -> dict:
    """Subsonic salted-token auth - the password itself never goes on the wire."""
    salt = secrets.token_hex(8)
    token = hashlib.md5(  # noqa: S324 - mandated by the Subsonic protocol
        (NAVIDROME_PASSWORD + salt).encode("utf-8")
    ).hexdigest()
    return {
        "u": NAVIDROME_USER,
        "t": token,
        "s": salt,
        "v": SUBSONIC_VERSION,
        "c": SUBSONIC_CLIENT,
        "f": "json",
    }


def _subsonic(endpoint: str, extra: dict = None) -> dict:
    params = _auth_params()
    if extra:
        params.update(extra)
    response = requests.get(
        f"{NAVIDROME_URL}/rest/{endpoint}", params=params, timeout=HTTP_TIMEOUT
    )
    response.raise_for_status()
    payload = response.json().get("subsonic-response", {})
    if payload.get("status") != "ok":
        error = payload.get("error", {})
        raise RuntimeError(
            f"Subsonic {endpoint} failed: {error.get('code')} {error.get('message')}"
        )
    return payload


def fetch_starred() -> list:
    """Return the starred songs as a list of dicts (may be empty)."""
    payload = _subsonic("getStarred2")
    songs = payload.get("starred2", {}).get("song", [])
    # Subsonic collapses a single-element list into an object in some clients;
    # normalise so callers can always iterate.
    if isinstance(songs, dict):
        songs = [songs]
    return songs


def unstar(song_id: str) -> None:
    _subsonic("unstar", {"id": song_id})


# ------------------------------------------------------- path translation
def translate_path(navidrome_path: str) -> str:
    """Map a Navidrome-side path onto the radio's mount point.

    Navidrome may report either an absolute path inside its own library root or
    a path relative to it, so both are accepted: any leading library root is
    stripped and the remainder is re-rooted at the radio's mount point.
    """
    path = navidrome_path.replace("\\", "/").strip()
    if NAVIDROME_LIBRARY_ROOT and path.startswith(NAVIDROME_LIBRARY_ROOT):
        path = path[len(NAVIDROME_LIBRARY_ROOT):]
    return posixpath.join(BETONIARKA_LIBRARY_ROOT, path.lstrip("/"))


def keywords_for(radio_path: str) -> list:
    """Distinctive path tokens for betoniarka's keyword search.

    Only word characters are kept: the radio feeds each token straight into a
    regex, so punctuation would either break the pattern or fail to match its
    own sanitised library tokens.
    """
    relative = radio_path
    if relative.startswith(BETONIARKA_LIBRARY_ROOT):
        relative = relative[len(BETONIARKA_LIBRARY_ROOT):]
    tokens, seen = [], set()
    for token in re.findall(r"\w+", relative, re.UNICODE):
        low = token.lower()
        if low == "mp3" or len(token) < 2 or low in seen:
            continue
        seen.add(low)
        tokens.append(token)
    return tokens


# ------------------------------------------------------------ radio io
def _radio_headers() -> dict:
    return {"X-Conjurer-Api-Key": CONJURER_API_KEY} if CONJURER_API_KEY else {}


def queue_via_api(radio_path: str) -> None:
    keywords = keywords_for(radio_path)
    if not keywords:
        raise RuntimeError(f"no usable keywords for {radio_path}")
    # betoniarka's wyszukaj() drops lista_slow[0] - it expects the Discord
    # command word there - so a sentinel takes that slot.
    payload = {"lista_slow": ["navidrome-bridge"] + keywords}
    response = requests.post(
        f"{BETONIARKA_URL}/request_radio_file",
        json=payload,
        headers=_radio_headers(),
        timeout=HTTP_TIMEOUT,
    )
    response.raise_for_status()


def queue_via_playlist(radio_path: str) -> None:
    if not Path(radio_path).exists():
        raise RuntimeError(
            f"{radio_path} not visible here - check the two library roots and the mount"
        )
    REQUEST_PLAYLIST.parent.mkdir(parents=True, exist_ok=True)
    with REQUEST_PLAYLIST.open("a", encoding="utf-8") as handle:
        handle.write(radio_path + "\n")


def queue(radio_path: str) -> None:
    if MODE == "playlist":
        queue_via_playlist(radio_path)
    else:
        queue_via_api(radio_path)


# --------------------------------------------------------------- state
def load_state() -> set:
    try:
        with STATE_FILE.open(encoding="utf-8") as handle:
            return set(json.load(handle).get("queued", []))
    except (FileNotFoundError, json.JSONDecodeError, OSError):
        return set()


def save_state(queued: set) -> None:
    try:
        STATE_FILE.parent.mkdir(parents=True, exist_ok=True)
        tmp = STATE_FILE.with_suffix(STATE_FILE.suffix + ".tmp")
        with tmp.open("w", encoding="utf-8") as handle:
            json.dump({"queued": sorted(queued)}, handle, indent=2)
        tmp.replace(STATE_FILE)
    except OSError as exc:
        LOG.warning("Cannot persist state to %s: %s", STATE_FILE, exc)


# ---------------------------------------------------------------- main
def process_once(already: set) -> set:
    """One poll cycle. Returns the updated set of handled song ids."""
    songs = fetch_starred()
    for song in songs:
        song_id = str(song.get("id", ""))
        if not song_id or song_id in already:
            continue

        navidrome_path = song.get("path", "")
        label = f"{song.get('artist', '?')} - {song.get('title', '?')}"
        if not navidrome_path:
            LOG.warning("Skipping %s (%s): Navidrome returned no path", label, song_id)
            already.add(song_id)
            continue

        radio_path = translate_path(navidrome_path)
        if DRY_RUN:
            LOG.info("[dry-run] %s\n    navidrome: %s\n    radio    : %s",
                     label, navidrome_path, radio_path)
            already.add(song_id)
            continue

        try:
            queue(radio_path)
        except (requests.exceptions.RequestException, RuntimeError, OSError) as exc:
            # Left out of `already`, so the next cycle retries it.
            LOG.error("Failed to queue %s: %s", label, exc)
            continue

        LOG.info("Queued for radio: %s -> %s", label, radio_path)
        already.add(song_id)

        if UNSTAR_AFTER_QUEUE:
            try:
                unstar(song_id)
                # The star is the trigger, not a record: once un-starred the
                # id can legitimately come back, so stop remembering it.
                already.discard(song_id)
            except (requests.exceptions.RequestException, RuntimeError) as exc:
                LOG.warning("Queued but could not un-star %s: %s", label, exc)
    return already


def main() -> int:
    logging.basicConfig(
        level=logging.INFO,
        format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
        stream=sys.stdout,
    )

    missing = [
        name for name, value in (
            ("NAVIDROME_USER", NAVIDROME_USER),
            ("NAVIDROME_PASSWORD", NAVIDROME_PASSWORD),
        ) if not value
    ]
    if missing:
        LOG.error("FATAL: missing required config: %s", ", ".join(missing))
        return 1
    if MODE not in ("api", "playlist"):
        LOG.error("FATAL: BRIDGE_MODE must be 'api' or 'playlist', got %r", MODE)
        return 1

    LOG.info("Navidrome %s -> betoniarka %s (mode=%s)", NAVIDROME_URL, BETONIARKA_URL, MODE)
    LOG.info("Path translation: %s -> %s", NAVIDROME_LIBRARY_ROOT, BETONIARKA_LIBRARY_ROOT)
    if DRY_RUN:
        LOG.info("DRY RUN - nothing will be queued")

    already = load_state()
    if not STATE_FILE.exists() and SKIP_EXISTING_ON_FIRST_RUN and not DRY_RUN:
        try:
            already = {str(song.get("id", "")) for song in fetch_starred()}
            save_state(already)
            LOG.info("First run: ignoring %d already-starred tracks", len(already))
        except (requests.exceptions.RequestException, RuntimeError) as exc:
            LOG.error("Could not read existing stars: %s", exc)
            return 1

    while True:
        try:
            updated = process_once(set(already))
            if updated != already:
                already = updated
                save_state(already)
        except (requests.exceptions.RequestException, RuntimeError) as exc:
            LOG.warning("Poll failed (retrying in %ss): %s", POLL_SECONDS, exc)
        time.sleep(POLL_SECONDS)


if __name__ == "__main__":
    try:
        sys.exit(main())
    except KeyboardInterrupt:
        LOG.info("Shutdown requested")
        sys.exit(0)