"""Wypelnia playback_sources.sort_date w istniejacych wierszach (migracja 0048).

Kopia scripts/backfill_scene_tags_sort_date.py dla playback_sources: partiami po zakresach
stron heapu, commit po kazdej partii, VACUUM co kilka partii, pauza oddaje dysk apce.
Nowe wiersze w trakcie wypelnia juz wyzwalacz z 0048. Wznawialny: rusza tylko wiersze z
sort_date IS NULL, na koncu dobiera resztki.

  docker compose run -d --name backfill_ps_sort worker \
      python3 -u /srv/scripts/backfill_playback_sort_date.py [stron_na_partie] [pauza_s]
Po nim: alembic upgrade (0049, indeks) i dopiero wtedy kod, ktory z indeksu korzysta.
"""
from __future__ import annotations

import sys
import time

from sqlalchemy import text

from app.db import engine

PAGES = int(sys.argv[1]) if len(sys.argv) > 1 else 1000
PAUSE = float(sys.argv[2]) if len(sys.argv) > 2 else 10.0
VACUUM_EVERY = 8
SORT_DATE = "COALESCE(s.release_date, (s.created_at AT TIME ZONE 'UTC')::date)"


def rel_pages() -> int:
    with engine.connect() as c:
        return int(c.execute(text(
            "SELECT pg_relation_size('playback_sources') / current_setting('block_size')::int"
        )).scalar())


def vacuum(analyze: bool = False) -> None:
    with engine.connect().execution_options(isolation_level="AUTOCOMMIT") as c:
        c.execute(text("VACUUM (ANALYZE) playback_sources" if analyze else "VACUUM playback_sources"))


t0 = time.time()
total = 0
page = 0
batch = 0
pages = rel_pages()
print(f"playback_sources: {pages} stron, partia {PAGES} stron, pauza {PAUSE} s", flush=True)
while page < pages:
    tb = time.time()
    with engine.begin() as c:
        c.execute(text("SET LOCAL statement_timeout = '600s'"))
        n = c.execute(text(f"""
            UPDATE playback_sources ps SET sort_date = {SORT_DATE}
              FROM scenes s
             WHERE s.id = ps.scene_id AND ps.sort_date IS NULL
               AND ps.ctid >= format('(%s,0)', CAST(:p0 AS int))::tid
               AND ps.ctid <  format('(%s,0)', CAST(:p1 AS int))::tid
        """), {"p0": page, "p1": page + PAGES}).rowcount
    total += n
    page += PAGES
    batch += 1
    if batch % VACUUM_EVERY == 0:
        vacuum()
        pages = rel_pages()  # tabela moze urosnac, zanim VACUUM zwolni miejsce
    print(f"partia {batch}: strony do {page}/{pages}, {n} wierszy w {time.time() - tb:.1f} s, "
          f"razem {total}, {time.time() - t0:.0f} s", flush=True)
    if n:
        time.sleep(PAUSE)

with engine.begin() as c:
    rest = c.execute(text(f"""
        UPDATE playback_sources ps SET sort_date = {SORT_DATE}
          FROM scenes s WHERE s.id = ps.scene_id AND ps.sort_date IS NULL
    """)).rowcount
print(f"resztki: {rest}", flush=True)
vacuum(analyze=True)
with engine.connect() as c:
    left = c.execute(text("SELECT count(*) FROM playback_sources WHERE sort_date IS NULL")).scalar()
print(f"KONIEC: {total + rest} wierszy, puste po wszystkim: {left}, {time.time() - t0:.0f} s", flush=True)