"""Database backups (pg_dump custom format, gzip-compressed by pg_dump) into AIA_DATA_DIR/backups. Off-node copies: scripts/backup-offnode.sh.
The dataset is worth more than the code — keep 30 dailies."""
from __future__ import annotations

import os
import shutil
import subprocess
from datetime import UTC, datetime
from pathlib import Path
from urllib.parse import urlparse

from aiatlas.config import settings


def _pg_dump() -> str:
    for candidate in ("/opt/homebrew/opt/postgresql@17/bin/pg_dump", "/opt/homebrew/bin/pg_dump", "/usr/local/bin/pg_dump", "pg_dump"):
        if shutil.which(candidate) or os.path.exists(candidate):
            return candidate
    raise RuntimeError("pg_dump not found")


def backup_database(keep: int = 30) -> Path:
    settings.ensure_dirs()
    url = urlparse(settings.sync_database_url)
    stamp = datetime.now(UTC).strftime("%Y%m%d-%H%M%S")
    out = settings.backups_dir / f"aiatlas-{stamp}.dump"
    env = dict(os.environ)
    if url.password:
        env["PGPASSWORD"] = url.password
    cmd = [_pg_dump(), "-Fc", "-Z", "6", "-f", str(out), "-h", url.hostname or "127.0.0.1", "-p", str(url.port or 5432), "-U", url.username or "aiatlas",
           (url.path or "/aiatlas").lstrip("/")]
    subprocess.run(cmd, check=True, env=env, timeout=3600)
    dumps = sorted(settings.backups_dir.glob("aiatlas-*.dump"))
    for old in dumps[:-keep]:
        old.unlink(missing_ok=True)
    return out


__all__ = ["backup_database"]