"""Mirror a locally-reachable Plex library into Siftlode's own catalog (plex_* tables).

Playback is from the local physical file, so this only mirrors METADATA + the physical-media facts
(codecs/container/path) needed to browse, search, and later play. It reuses Plex's own codec info
(no ffprobe needed) to classify each item's browser playability. Movies + episodes become playable
LEAF rows (plex_items); shows/seasons are mirrored for the drill-down + episode ordering.

The sync is a full reconcile of the enabled sections (upsert by rating_key). Pruning of items that
disappeared from Plex is intentionally left for later (a follow-up can diff rating_keys per library).
Cast + intro/credit markers are fetched lazily on the item-detail/player path (P2), not here.
"""
import logging
from datetime import datetime, timezone

from sqlalchemy.orm import Session

from app import sysconfig
from app.models import PlexItem, PlexLibrary, PlexSeason, PlexShow
from app.plex.client import PlexClient, PlexError, PlexNotConfigured

log = logging.getLogger("siftlode.plex")

# Codecs/containers a browser can play in a native <video> without any transcoding.
_BROWSER_VIDEO = {"h264"}
_BROWSER_AUDIO = {"aac", "mp3", "opus", "vorbis"}
_BROWSER_CONTAINER = {"mp4", "mov", "m4v"}

# Plex section item types.
_TYPE_MOVIE = 1
_TYPE_SHOW = 2
_TYPE_SEASON = 3
_TYPE_EPISODE = 4

_PAGE = 200


def classify_playable(vcodec: str | None, acodec: str | None, container: str | None) -> str:
    """How the browser can play this file: 'direct' (native <video>), 'remux' (copy video, fix
    container / transcode audio — cheap), or 'transcode' (re-encode video — expensive)."""
    v = (vcodec or "").lower()
    a = (acodec or "").lower()
    c = (container or "").lower()
    if not v or v not in _BROWSER_VIDEO:
        return "transcode"
    if a and a not in _BROWSER_AUDIO:
        return "remux"
    if c and c not in _BROWSER_CONTAINER:
        return "remux"
    return "direct"


def _epoch(v) -> datetime | None:
    try:
        return datetime.fromtimestamp(int(v), tz=timezone.utc) if v else None
    except (TypeError, ValueError, OSError):
        return None


def _media_facts(meta: dict) -> dict:
    media = meta.get("Media") or []
    if not media:
        return {}
    m = media[0]
    part = (m.get("Part") or [{}])[0]
    return {
        "container": m.get("container") or part.get("container"),
        "codec_video": m.get("videoCodec"),
        "codec_audio": m.get("audioCodec"),
        "size_bytes": part.get("size"),
        "file_path": part.get("file"),
        "part_key": part.get("key"),
    }


def _dur_s(meta: dict) -> int | None:
    d = meta.get("duration")
    return int(d / 1000) if d else None


def _enabled_section_keys(db: Session) -> set[str] | None:
    """The configured allowlist of section keys, or None to mean 'all movie/show sections'."""
    raw = sysconfig.get_str(db, "plex_libraries")
    keys = {k.strip() for k in raw.split(",") if k.strip()}
    return keys or None


def sync(db: Session) -> dict:
    """Full reconcile of the enabled movie/show sections. Returns a small stats dict."""
    if not sysconfig.get_bool(db, "plex_enabled"):
        return {"skipped": "disabled"}
    stats = {"libraries": 0, "movies": 0, "shows": 0, "seasons": 0, "episodes": 0}
    wanted = _enabled_section_keys(db)
    try:
        with PlexClient(db) as plex:
            for s in plex.sections():
                if s.get("type") not in ("movie", "show"):
                    continue
                key = str(s.get("key"))
                if wanted is not None and key not in wanted:
                    continue
                lib = _upsert_library(db, key, s.get("title") or key, s.get("type"))
                stats["libraries"] += 1
                if s.get("type") == "movie":
                    _sync_movies(db, plex, lib, stats)
                else:
                    _sync_shows(db, plex, lib, stats)
            db.commit()
    except PlexNotConfigured as e:
        return {"skipped": str(e)}
    except PlexError as e:
        db.rollback()
        log.warning("Plex sync failed: %s", e)
        return {"error": str(e)}
    log.info("Plex sync done: %s", stats)
    return stats


def _upsert_library(db: Session, key: str, title: str, kind: str) -> PlexLibrary:
    lib = db.query(PlexLibrary).filter_by(plex_key=key).first()
    if lib is None:
        lib = PlexLibrary(plex_key=key)
        db.add(lib)
    lib.title = title
    lib.kind = kind
    lib.synced_at = datetime.now(timezone.utc)
    db.flush()
    return lib


def _paginate(plex: PlexClient, key: str, item_type: int):
    start = 0
    while True:
        items, total = plex.section_items(key, item_type, start, _PAGE)
        if not items:
            break
        for it in items:
            yield it
        start += len(items)
        if total and start >= total:
            break
        if len(items) < _PAGE:
            break


def _apply_item(row: PlexItem, lib_id: int, kind: str, meta: dict) -> None:
    row.library_id = lib_id
    row.kind = kind
    row.title = (meta.get("title") or "").strip() or "Untitled"
    row.summary = meta.get("summary")
    row.year = meta.get("year")
    row.duration_s = _dur_s(meta)
    row.thumb_key = meta.get("thumb")
    row.art_key = meta.get("art") or meta.get("grandparentArt")
    row.added_at = _epoch(meta.get("addedAt"))
    mf = _media_facts(meta)
    row.file_path = mf.get("file_path")
    row.part_key = mf.get("part_key")
    row.container = mf.get("container")
    row.codec_video = mf.get("codec_video")
    row.codec_audio = mf.get("codec_audio")
    row.size_bytes = mf.get("size_bytes")
    row.playable = classify_playable(mf.get("codec_video"), mf.get("codec_audio"), mf.get("container"))


def _sync_movies(db: Session, plex: PlexClient, lib: PlexLibrary, stats: dict) -> None:
    existing = {r.rating_key: r for r in db.query(PlexItem).filter_by(library_id=lib.id, kind="movie")}
    for meta in _paginate(plex, lib.plex_key, _TYPE_MOVIE):
        rk = str(meta.get("ratingKey") or "")
        if not rk:
            continue
        row = existing.get(rk) or PlexItem(rating_key=rk)
        if row.id is None:
            db.add(row)
        _apply_item(row, lib.id, "movie", meta)
        stats["movies"] += 1
    db.flush()


def _sync_shows(db: Session, plex: PlexClient, lib: PlexLibrary, stats: dict) -> None:
    # 1) shows
    shows = {r.rating_key: r for r in db.query(PlexShow).filter_by(library_id=lib.id)}
    for meta in _paginate(plex, lib.plex_key, _TYPE_SHOW):
        rk = str(meta.get("ratingKey") or "")
        if not rk:
            continue
        sh = shows.get(rk) or PlexShow(rating_key=rk)
        if sh.id is None:
            db.add(sh)
            shows[rk] = sh
        sh.library_id = lib.id
        sh.title = (meta.get("title") or "").strip() or "Untitled"
        sh.summary = meta.get("summary")
        sh.year = meta.get("year")
        sh.thumb_key = meta.get("thumb")
        sh.art_key = meta.get("art")
        sh.child_count = meta.get("childCount")
        sh.added_at = _epoch(meta.get("addedAt"))
        stats["shows"] += 1
    db.flush()
    show_id = {rk: sh.id for rk, sh in shows.items()}

    # 2) seasons
    seasons = {r.rating_key: r for r in db.query(PlexSeason).join(PlexShow).filter(PlexShow.library_id == lib.id)}
    for meta in _paginate(plex, lib.plex_key, _TYPE_SEASON):
        rk = str(meta.get("ratingKey") or "")
        sid = show_id.get(str(meta.get("parentRatingKey") or ""))
        if not rk or sid is None:
            continue
        se = seasons.get(rk) or PlexSeason(rating_key=rk)
        if se.id is None:
            db.add(se)
            seasons[rk] = se
        se.show_id = sid
        se.title = meta.get("title")
        se.season_number = meta.get("index")
        se.thumb_key = meta.get("thumb")
        stats["seasons"] += 1
    db.flush()
    season_id = {rk: se.id for rk, se in seasons.items()}

    # 3) episodes (playable leaves)
    episodes = {r.rating_key: r for r in db.query(PlexItem).filter_by(library_id=lib.id, kind="episode")}
    for meta in _paginate(plex, lib.plex_key, _TYPE_EPISODE):
        rk = str(meta.get("ratingKey") or "")
        if not rk:
            continue
        row = episodes.get(rk) or PlexItem(rating_key=rk)
        if row.id is None:
            db.add(row)
        _apply_item(row, lib.id, "episode", meta)
        row.show_id = show_id.get(str(meta.get("grandparentRatingKey") or ""))
        row.season_id = season_id.get(str(meta.get("parentRatingKey") or ""))
        row.season_number = meta.get("parentIndex")
        row.episode_number = meta.get("index")
        stats["episodes"] += 1
    db.flush()