import json
import re
import subprocess
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)
    _write_playlists_json(db)

    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 _write_playlists_json(db: Session) -> None:
    """The file regen.sh reads. Every active-or-not playlist is included
    (see regen.sh's header comment) so a manual run is always possible;
    the scheduler is what actually skips inactive ones."""
    playlists = list_all(db)
    payload = [
        {
            "name": p.name,
            "spotify_url": p.spotify_url,
            "active": p.active,
            "no_m3u": p.no_m3u,
        }
        for p in playlists
    ]
    settings.pipeline_config_dir.mkdir(parents=True, exist_ok=True)
    out_path = settings.pipeline_config_dir / "playlists.json"
    out_path.write_text(json.dumps(payload, indent=2))


def regenerate_confs(db: Session) -> subprocess.CompletedProcess:
    """Write playlists.json, then run regen.sh to render/refresh every
    playlist's .conf file. Newly-created .conf files still have unpatched
    SOULSEEK_USER/SOULSEEK_PASS/SPOTIFY_CLIENT_ID/SPOTIFY_CLIENT_SECRET
    placeholders at this point -- _sync_to_disk() (this function's caller)
    re-renders credentials into them immediately afterward."""
    _write_playlists_json(db)
    regen_script = settings.pipeline_dir / "configs" / "regen.sh"
    return subprocess.run(
        [str(regen_script)],
        capture_output=True,
        text=True,
        env={
            "ALEMBIC_CONFIG_DIR": str(settings.alembic_config_dir),
            "MUSIC_DATA_DIR": str(settings.music_data_dir),
            "PIPELINE_DIR": str(settings.pipeline_dir),
            # Must include /opt/venv/bin: regen.sh shells out to `python3`
            # to parse playlists.json, and that's where this image's Python
            # actually lives (confirmed against the real container -- a
            # bare /usr/bin:/bin PATH made every regen.sh call silently
            # generate zero .conf files, no error surfaced to the caller).
            "PATH": "/opt/venv/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
        },
    )


def _sync_to_disk(db: Session) -> None:
    """Convenience wrapper used by create()/update(): regenerate confs,
    immediately re-patch credentials into any newly-rendered file, 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."""
    regenerate_confs(db)
    # Imported lazily to avoid a circular import (credential_service and
    # scheduler_service don't depend on playlist_service, but importing at
    # module load time would still work here — done lazily anyway to keep
    # the dependency direction obvious as all three services grow).
    from app.services import credential_service, scheduler_service

    credential_service.render_scope(db, "soulseek")
    credential_service.render_scope(db, "spotify")

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