#!/usr/bin/env python3
"""
PostgreSQL backup script for SeaFare Montana.
Run via cron or manually: python backup_db.py

Backs up the database to a timestamped SQL file.
Usage:
    python backup_db.py                  # Backup to ./backups/
    python backup_db.py /path/to/dir     # Backup to specified dir
"""
import os
import sys
import subprocess
from datetime import datetime
from pathlib import Path

from dotenv import load_dotenv
load_dotenv()

DATABASE_URL = os.environ.get('DATABASE_URL')

def backup():
    if not DATABASE_URL:
        print("ERROR: DATABASE_URL not set. Cannot backup SQLite — just copy the .db file.")
        sys.exit(1)

    backup_dir = Path(sys.argv[1]) if len(sys.argv) > 1 else Path(__file__).parent / 'backups'
    backup_dir.mkdir(parents=True, exist_ok=True)

    timestamp = datetime.utcnow().strftime('%Y%m%d_%H%M%S')
    filename = backup_dir / f'seafare_backup_{timestamp}.sql'

    print(f"Backing up to {filename}...")

    # pg_dump using DATABASE_URL
    result = subprocess.run(
        ['pg_dump', DATABASE_URL, '--no-owner', '--no-acl', '-f', str(filename)],
        capture_output=True, text=True
    )

    if result.returncode != 0:
        print(f"ERROR: pg_dump failed: {result.stderr}")
        sys.exit(1)

    size_kb = filename.stat().st_size / 1024
    print(f"Backup complete: {filename} ({size_kb:.1f} KB)")

    # Keep only last 10 backups
    backups = sorted(backup_dir.glob('seafare_backup_*.sql'), reverse=True)
    for old in backups[10:]:
        old.unlink()
        print(f"Removed old backup: {old.name}")

if __name__ == '__main__':
    backup()