#!/usr/bin/env python3
"""
Backup Runner

Creates a daily pg_dump backup of the PostgreSQL database, compresses it,
and retains only the last 7 days of backups.

Designed to run as a periodic cron job (daily) inside the Docker container.
Backups are written to /backups which is mounted to a Synology shared folder.
"""

import argparse
import logging
import os
import subprocess
from datetime import datetime, timedelta

from logging_utils import setup_logging

BACKUP_DIR = "/backups"
RETENTION_DAYS = 7


def run_backup():
    """Run pg_dump and compress the output."""
    today = datetime.now().strftime("%Y%m%d")
    backup_file = os.path.join(BACKUP_DIR, f"hyper_{today}.sql.gz")

    os.makedirs(BACKUP_DIR, exist_ok=True)

    logging.info(f"Starting backup to {backup_file}")

    cmd = f"pg_dump -h postgres -U hyper hyper | gzip > {backup_file}"
    result = subprocess.run(cmd, shell=True, capture_output=True, text=True)

    if result.returncode == 0:
        file_size = os.path.getsize(backup_file)
        logging.info(f"Backup completed: {backup_file} ({file_size:,} bytes)")
    else:
        logging.error(f"Backup failed: {result.stderr}")
        if os.path.exists(backup_file):
            os.remove(backup_file)

    cleanup_old_backups()


def cleanup_old_backups():
    """Delete backup files older than RETENTION_DAYS."""
    cutoff = datetime.now() - timedelta(days=RETENTION_DAYS)

    if not os.path.exists(BACKUP_DIR):
        return

    for filename in os.listdir(BACKUP_DIR):
        if filename.startswith("hyper_") and filename.endswith(".sql.gz"):
            filepath = os.path.join(BACKUP_DIR, filename)
            mtime = datetime.fromtimestamp(os.path.getmtime(filepath))
            if mtime < cutoff:
                os.remove(filepath)
                logging.info(f"Deleted old backup: {filename}")


def main():
    parser = argparse.ArgumentParser(description="Run PostgreSQL backup.")
    parser.add_argument("--log-level", default="normal", choices=['off', 'normal', 'debug'])
    args = parser.parse_args()

    setup_logging(args.log_level, 'BackupRunner')

    run_backup()


if __name__ == "__main__":
    main()