#!/usr/bin/env python3
"""Prune self-referential / stale debug rows from newOS4 telemetry.

Read-only unless --apply. Coordinates with PHP via the SAME flock on errors.json
(ingest.php opens it 'c' + LOCK_EX), and always archives before rewriting.
"""
import argparse, fcntl, json, os, re, time

ROOT = '/var/www/webx11.duckdns.org/spaces/newos4'
DEBUG = os.path.join(ROOT, 'data', 'debug')
ERRORS = os.path.join(DEBUG, 'errors.json')
ARCHIVE = os.path.join(DEBUG, 'archive')
SELF = re.compile(r'/api/debug/(ingest|report)\.php', re.I)


def iso_to_epoch(s):
    """Parse '2026-10-20T16:57:31.589Z' or '...+00:00'. Returns None when unparseable."""
    if not s:
        return None
    t = str(s).strip().replace('Z', '+00:00')
    if '.' in t:
        head, rest = t.split('.', 1)
        frac = rest[:6].ljust(6, '0')
        tail = rest[6:]
        t = f'{head}.{frac}{tail}'
    try:
        import datetime
        d = datetime.datetime.fromisoformat(t)
        if d.tzinfo is None:
            d = d.replace(tzinfo=datetime.timezone.utc)
        return d.timestamp()
    except Exception:
        return None


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument('--apply', action='store_true')
    ap.add_argument('--max-age-days', type=int, default=30)
    a = ap.parse_args()
    cutoff = time.time() - a.max_age_days * 86400

    fp = open(ERRORS, 'r+', encoding='utf-8')
    fcntl.flock(fp, fcntl.LOCK_EX)
    try:
        errors = json.load(fp) or []
        keep, drop = [], []
        for e in errors:
            msg = str(e.get('message', ''))
            age_ref = iso_to_epoch(e.get('last_seen')) or iso_to_epoch(e.get('ingested_at'))
            if SELF.search(msg):
                drop.append((e, 'self-referential'))
            elif age_ref is not None and age_ref < cutoff:
                drop.append((e, f'older than {a.max_age_days}d'))
            else:
                keep.append(e)

        print(f'records={len(errors)} keep={len(keep)} drop={len(drop)}')
        reasons = {}
        for e, why in drop:
            reasons[why] = reasons.get(why, 0) + 1
        for why, n in sorted(reasons.items()):
            print(f'  drop {n:>2} reason={why}')
        for e, why in drop[:8]:
            print(f"    count={e.get('count')} {why}: {str(e.get('message'))[:80]}")
        print(f"occurrences before={sum(int(e.get('count') or 1) for e in errors)} "
              f"after={sum(int(e.get('count') or 1) for e in keep)}")

        if not a.apply:
            print('dry-run; re-run with --apply to write')
            return

        os.makedirs(ARCHIVE, exist_ok=True)
        archive = os.path.join(ARCHIVE, f'errors-{time.strftime("%Y%m%d_%H%M%S")}.json')
        with open(archive, 'w', encoding='utf-8') as af:
            json.dump(errors, af, indent=2)
        os.chmod(archive, 0o644)

        fp.seek(0)
        fp.truncate()
        json.dump(keep, fp, indent=2)
        fp.flush()
        os.fsync(fp.fileno())
        open(os.path.join(DEBUG, '.rebuild_clusters'), 'w').write(str(int(time.time())))
        print(f'applied: {archive} written, errors.json rewritten, cluster rebuild flagged')
    finally:
        fcntl.flock(fp, fcntl.LOCK_UN)
        fp.close()


if __name__ == '__main__':
    main()