#!/usr/bin/env python3
from __future__ import annotations

import argparse
import os
import sqlite3
import sys
from datetime import datetime, timedelta, timezone
from pathlib import Path
from typing import Tuple


def _utc_now() -> datetime:
    return datetime.now(timezone.utc)


def _fmt_ts(dt: datetime) -> str:
    return dt.strftime("%Y-%m-%dT%H:%M:%SZ")


def _resolve_data_dir(cli_data_dir: str | None) -> Path:
    raw = (cli_data_dir or os.getenv("SOFIIA_DATA_DIR") or "/app/data").strip()
    return Path(raw).expanduser().resolve()


def _parse_args() -> argparse.Namespace:
    p = argparse.ArgumentParser(
        description="Prune old audit_events records from sofiia SQLite DB."
    )
    p.add_argument(
        "--data-dir",
        default=None,
        help="Path to SOFIIA_DATA_DIR. Defaults to env SOFIIA_DATA_DIR or /app/data.",
    )
    p.add_argument(
        "--retention-days",
        type=int,
        default=None,
        help="Retention period in days. Defaults to SOFIIA_AUDIT_RETENTION_DAYS or 90.",
    )
    p.add_argument(
        "--batch-size",
        type=int,
        default=5000,
        help="Delete batch size (default: 5000).",
    )
    p.add_argument(
        "--dry-run",
        action="store_true",
        help="Report candidates only, do not delete.",
    )
    p.add_argument(
        "--vacuum",
        action="store_true",
        help="Run VACUUM after deletion.",
    )
    p.add_argument(
        "--yes",
        action="store_true",
        help="Reserved for non-interactive confirmation (no-op in current script).",
    )
    return p.parse_args()


def _check_table_exists(conn: sqlite3.Connection, table_name: str) -> bool:
    row = conn.execute(
        "SELECT name FROM sqlite_master WHERE type='table' AND name=?",
        (table_name,),
    ).fetchone()
    return bool(row)


def _candidate_stats(conn: sqlite3.Connection, cutoff_ts: str) -> Tuple[int, str | None, str | None]:
    row = conn.execute(
        "SELECT COUNT(*), MIN(ts), MAX(ts) FROM audit_events WHERE ts < ?",
        (cutoff_ts,),
    ).fetchone()
    if not row:
        return 0, None, None
    return int(row[0] or 0), row[1], row[2]


def main() -> int:
    args = _parse_args()

    data_dir = _resolve_data_dir(args.data_dir)
    db_path = (data_dir / "sofiia.db").resolve()
    retention_days = args.retention_days
    if retention_days is None:
        retention_days = int(os.getenv("SOFIIA_AUDIT_RETENTION_DAYS", "90"))
    retention_days = max(1, int(retention_days))
    batch_size = max(1, int(args.batch_size))

    cutoff_dt = _utc_now() - timedelta(days=retention_days)
    cutoff_ts = _fmt_ts(cutoff_dt)

    print("Audit retention pruning")
    print(f"  db_path: {db_path}")
    print(f"  retention_days: {retention_days}")
    print(f"  cutoff_ts: {cutoff_ts}")
    print(f"  batch_size: {batch_size}")
    print(f"  dry_run: {bool(args.dry_run)}")
    print(f"  vacuum: {bool(args.vacuum)}")

    if not db_path.exists():
        print(f"ERROR: DB file not found: {db_path}")
        return 1

    try:
        conn = sqlite3.connect(str(db_path))
        conn.execute("PRAGMA busy_timeout = 5000")
    except Exception as exc:
        print(f"ERROR: cannot open DB: {exc}")
        return 1

    try:
        if not _check_table_exists(conn, "audit_events"):
            print("ERROR: table 'audit_events' not found in DB schema")
            return 1

        total_candidates, min_ts, max_ts = _candidate_stats(conn, cutoff_ts)
        print(f"  candidates: {total_candidates}")
        print(f"  candidates_min_ts: {min_ts or '-'}")
        print(f"  candidates_max_ts: {max_ts or '-'}")

        if args.dry_run:
            print("Dry-run complete. No rows were deleted.")
            return 0

        deleted_total = 0
        batch_no = 0
        while True:
            cur = conn.execute(
                "DELETE FROM audit_events WHERE id IN ("
                "SELECT id FROM audit_events WHERE ts < ? ORDER BY ts ASC LIMIT ?"
                ")",
                (cutoff_ts, batch_size),
            )
            deleted = int(cur.rowcount or 0)
            if deleted <= 0:
                break
            conn.commit()
            deleted_total += deleted
            batch_no += 1
            print(f"  batch {batch_no}: deleted {deleted} (total={deleted_total})")

        print(f"Deletion complete. Total deleted: {deleted_total}")

        if args.vacuum:
            print("Running VACUUM...")
            conn.execute("VACUUM")
            print("VACUUM complete.")

        return 0
    except Exception as exc:
        print(f"ERROR: prune failed: {exc}")
        return 1
    finally:
        conn.close()


if __name__ == "__main__":
    sys.exit(main())