"""Phash backfill dla scen z thumbnail_url ale bez fingerprint(kind='phash').

Po this run:
- find_by_phash_within() znajduje exact + Hamming-near duplicates dla tube scen
- phash_dedup_scenes.py auto-merge wykryje exact match duplicaty
- merge_candidates flow może użyć phash distance jako signal

Implementacja:
- Cursor-based pagination po scene_id (no skip-on-fail bug)
- Threadpool concurrency dla httpx (CPU-bound phash calc + I/O fetch)
- Per-scene SAVEPOINT — failure w jednej scenie nie psuje całego batch'a
- Idempotent: scena z istniejącym phash entry (kind='phash') jest skip'owana

Run: `python /srv/scripts/backfill_phash_tube.py --limit 5000 --concurrency 10`
"""
from __future__ import annotations

import argparse
import logging
import sys
import time
from concurrent.futures import ThreadPoolExecutor, as_completed

import httpx
from sqlalchemy import select, func
from sqlalchemy.orm import Session

sys.path.insert(0, "/srv")
from app.connectors.direct_scrapers._browse_base import compute_thumbnail_phash
from app.db import SessionLocal
from app.models.playback_source import PlaybackSource
from app.models.scene import ScenePerformer, SceneFingerprint

log = logging.getLogger("backfill_phash")
logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(message)s")


def _scenes_needing_phash(session: Session, batch: int, after_id, performer_id=None) -> list[tuple]:
    """Zwraca [(scene_id, thumbnail_url, page_url), ...] — pierwszy alive thumb
    per scena, dla scen BEZ istniejącego phash entry.

    `performer_id` (optional): ograniczenie do scen w których uczestniczy ten
    performer — przydatne do benchmarków per-performer (Imbarbielu, Aletta Ocean).
    """
    sub = (
        select(SceneFingerprint.scene_id)
        .where(SceneFingerprint.kind == "phash")
        .scalar_subquery()
    )
    q = (
        select(
            PlaybackSource.scene_id,
            func.min(PlaybackSource.thumbnail_url).label("thumb_url"),
            func.min(PlaybackSource.page_url).label("page_url"),
        )
        .where(PlaybackSource.dead_at.is_(None))
        .where(PlaybackSource.thumbnail_url.isnot(None))
        .where(PlaybackSource.scene_id.notin_(sub))
        .group_by(PlaybackSource.scene_id)
        .order_by(PlaybackSource.scene_id)
        .limit(batch)
    )
    if performer_id is not None:
        perf_sub = (
            select(ScenePerformer.scene_id)
            .where(ScenePerformer.performer_id == performer_id)
            .scalar_subquery()
        )
        q = q.where(PlaybackSource.scene_id.in_(perf_sub))
    if after_id is not None:
        q = q.where(PlaybackSource.scene_id > after_id)
    return list(session.execute(q).all())


def _compute_one(item: tuple) -> tuple:
    """Worker thread fn — fetch + phash. Returns (scene_id, phash_or_None)."""
    scene_id, thumb_url, page_url = item
    if not thumb_url:
        return (scene_id, None)
    try:
        from urllib.parse import urlparse
        host = urlparse(page_url or "").hostname if page_url else None
        referer = f"https://{host}/" if host else None
        ph = compute_thumbnail_phash(thumb_url, referer=referer, timeout=8.0)
        return (scene_id, ph)
    except (httpx.HTTPError, OSError, ValueError) as e:
        log.debug("phash fetch fail %s: %s", thumb_url, e)
        return (scene_id, None)
    except Exception as e:
        log.warning("phash unexpected %s: %s", thumb_url, e)
        return (scene_id, None)


def main() -> None:
    import uuid as _uuid
    ap = argparse.ArgumentParser()
    ap.add_argument("--batch", type=int, default=200, help="scenes per DB query batch")
    ap.add_argument("--limit", type=int, default=10_000, help="max scenes total")
    ap.add_argument("--concurrency", type=int, default=10, help="parallel fetches")
    ap.add_argument("--performer-id", type=str, default=None, help="filter to scenes of this performer (UUID)")
    args = ap.parse_args()
    performer_id = _uuid.UUID(args.performer_id) if args.performer_id else None

    total = ok = fail = 0
    cursor = None
    started = time.monotonic()

    while total < args.limit:
        with SessionLocal() as session:
            batch = _scenes_needing_phash(session, batch=args.batch, after_id=cursor, performer_id=performer_id)
            if not batch:
                log.info("no more scenes (cursor=%s, done)", cursor)
                break
            cursor = batch[-1].scene_id

            with ThreadPoolExecutor(max_workers=args.concurrency) as pool:
                futures = [pool.submit(_compute_one, tuple(row)) for row in batch]
                for fut in as_completed(futures):
                    scene_id, ph = fut.result()
                    total += 1
                    if not ph:
                        fail += 1
                        continue
                    try:
                        sp = session.begin_nested()
                        session.add(SceneFingerprint(
                            scene_id=scene_id, kind="phash", value=ph,
                        ))
                        sp.commit()
                        ok += 1
                    except Exception as e:
                        log.debug("insert fail scene=%s: %s", scene_id, e)
                        fail += 1
            session.commit()

            elapsed = time.monotonic() - started
            rate = total / elapsed if elapsed > 0 else 0
            log.info(
                "progress total=%d ok=%d fail=%d rate=%.1f/s cursor=%s",
                total, ok, fail, rate, cursor,
            )

    elapsed = time.monotonic() - started
    log.info("done total=%d ok=%d fail=%d elapsed=%.1fs", total, ok, fail, elapsed)


if __name__ == "__main__":
    main()