alembic/app/services/playlist_service.py

import json
import re
import time

from sqlalchemy import select
from sqlalchemy.orm import Session

from app.models import Playlist
from app.settings import settings

# A playlist name becomes a filename (<name>.conf), a directory under the
# Soulseek dropbox, an M3U path, and a log path, and it is substituted into
# rendered config files. Restrict it to a small safe charset so it can never
# escape those paths (../) or inject config/shell content. Kept deliberately
# tight; if a user wants a fancier display name that's a separate field to add
# later, not a reason to loosen the on-disk identifier.
_VALID_NAME = re.compile(r"^[A-Za-z0-9 _-]{1,64}$")


def validate_name(name: str) -> str:
    """Return the name unchanged if it is a safe on-disk identifier, else
    raise ValueError with a message suitable for showing to the user."""
    cleaned = (name or "").strip()
    if not _VALID_NAME.match(cleaned):
        raise ValueError(
            "Playlist name must be 1-64 characters using only letters, "
            "numbers, spaces, hyphens and underscores."
        )
    return cleaned


def cron_to_time(cron_expr: str | None) -> str:
    """'30 1 * * *' -> '01:30'. Every playlist schedule today is a simple
    daily HH:MM (no day-of-week/day-of-month complexity -- that's only used
    by a couple of maintenance jobs), so the UI can offer a plain time
    picker instead of raw cron syntax. Returns '' for anything else
    (unscheduled, or a cron expression more complex than daily-at-HH:MM)."""
    if not cron_expr:
        return ""
    parts = cron_expr.split()
    if len(parts) == 5 and parts[2] == "*" and parts[3] == "*" and parts[4] == "*":
        try:
            hour, minute = int(parts[1]), int(parts[0])
            if 0 <= hour < 24 and 0 <= minute < 60:
                return f"{hour:02d}:{minute:02d}"
        except ValueError:
            pass
    return ""


def time_to_cron(time_str: str | None) -> str | None:
    """'01:30' -> '30 1 * * *'. Empty/invalid input means unscheduled."""
    if not time_str:
        return None
    try:
        hour_str, minute_str = time_str.split(":")
        hour, minute = int(hour_str), int(minute_str)
    except ValueError:
        return None
    if not (0 <= hour < 24 and 0 <= minute < 60):
        return None
    return f"{minute} {hour} * * *"

def list_all(db: Session) -> list[Playlist]:
    return list(db.execute(select(Playlist).order_by(Playlist.name)).scalars())


def get(db: Session, playlist_id: int) -> Playlist | None:
    return db.get(Playlist, playlist_id)


def get_by_name(db: Session, name: str) -> Playlist | None:
    return db.execute(select(Playlist).where(Playlist.name == name)).scalar_one_or_none()


def create(
    db: Session,
    name: str,
    spotify_url: str,
    active: bool = True,
    no_m3u: bool = False,
    notes: str | None = None,
    cron_expr: str | None = None,
) -> Playlist:
    name = validate_name(name)
    now = time.time()
    playlist = Playlist(
        name=name,
        spotify_url=spotify_url,
        active=active,
        no_m3u=no_m3u,
        notes=notes,
        cron_expr=cron_expr,
        created_at=now,
        updated_at=now,
    )
    db.add(playlist)
    db.commit()
    db.refresh(playlist)
    _sync_to_disk(db)
    return playlist


def update(db: Session, playlist_id: int, **fields) -> Playlist:
    playlist = db.get(Playlist, playlist_id)
    if playlist is None:
        raise ValueError(f"no playlist with id={playlist_id}")
    for key, value in fields.items():
        setattr(playlist, key, value)
    playlist.updated_at = time.time()
    db.commit()
    db.refresh(playlist)
    _sync_to_disk(db)
    return playlist


def delete(db: Session, playlist_id: int) -> None:
    """Remove the playlist from the DB and delete its rendered .conf file.
    Does NOT touch anything already downloaded/imported for it — that's a
    library decision, not a playlist-definition one."""
    playlist = db.get(Playlist, playlist_id)
    if playlist is None:
        return
    name = playlist.name
    db.delete(playlist)
    db.commit()
    conf_path = settings.pipeline_config_dir / f"{name}.conf"
    conf_path.unlink(missing_ok=True)

    from app.services import scheduler_service

    scheduler = scheduler_service.get_scheduler()
    if scheduler is not None:
        scheduler_service.sync_playlist_jobs(scheduler)


def seed_legacy(db: Session) -> int:
    """One-time import of playlists from an optional legacy-playlists.json in
    the config dir (migration helper). This is not personal data baked into
    the code: point it at your own export. Each entry is an object with
    "name", "spotify_url", and optional "cron_expr" and "no_m3u". Skips any
    name that already exists. Returns the number of rows created, or 0 if the
    file is absent.

    Example legacy-playlists.json:
      [{"name": "techno", "spotify_url": "https://open.spotify.com/playlist/...",
        "cron_expr": "0 1 * * *", "no_m3u": false}]
    """
    legacy_path = settings.pipeline_config_dir / "legacy-playlists.json"
    if not legacy_path.exists():
        return 0
    entries = json.loads(legacy_path.read_text())
    created = 0
    for entry in entries:
        name = entry["name"]
        if get_by_name(db, name) is not None:
            continue
        create(
            db,
            name=name,
            spotify_url=entry["spotify_url"],
            no_m3u=entry.get("no_m3u", False),
            cron_expr=entry.get("cron_expr"),
        )
        created += 1
    return created


def _sync_to_disk(db: Session) -> None:
    """Called by create()/update()/delete(): re-render every playlist's sldl
    .conf (with credentials substituted, in-app -- no regen.sh subprocess or
    playlists.json round-trip anymore) and push the change to the live
    scheduler if one is running. This is what makes add/remove-in-the-UI take
    effect without a redeploy.

    Imported lazily to keep the dependency direction obvious (credential_service
    and scheduler_service don't import playlist_service at module load)."""
    from app.services import credential_service, scheduler_service

    credential_service.render_playlist_confs(db)

    scheduler = scheduler_service.get_scheduler()
    if scheduler is not None:
        scheduler_service.sync_playlist_jobs(scheduler)