"""Daily PostgreSQL backup with 7-day retention.

Cron: 0 3 * * * cd /opt/voidea && python tools/backup_db.py
"""

import datetime
import os
import subprocess
import sys

BACKUP_DIR = os.environ.get("BACKUP_DIR", "/opt/voidea/backups")
RETENTION_DAYS = int(os.environ.get("BACKUP_RETENTION_DAYS", "7"))
DB_URL = os.environ.get("DATABASE_URL", "")


def parse_db_url(url: str) -> dict:
    """Parse DATABASE_URL into pg_dump arguments."""
    if not url:
        print("ERROR: DATABASE_URL not set", file=sys.stderr)
        sys.exit(1)
    parts = url.replace("postgresql://", "").replace("postgres://", "").split("@")
    user_pass = parts[0].split(":")
    host_db = parts[1].split("/")
    host_port = host_db[0].split(":")
    return {
        "user": user_pass[0],
        "password": user_pass[1] if len(user_pass) > 1 else "",
        "host": host_port[0],
        "port": host_port[1] if len(host_port) > 1 else "5432",
        "dbname": host_db[1].split("?")[0],
    }


def main():
    os.makedirs(BACKUP_DIR, exist_ok=True)
    config = parse_db_url(DB_URL)

    timestamp = datetime.datetime.now().strftime("%Y%m%d_%H%M%S")
    filename = f"voidea_backup_{timestamp}.sql.gz"
    filepath = os.path.join(BACKUP_DIR, filename)

    env = os.environ.copy()
    env["PGPASSWORD"] = config["password"]

    cmd = [
        "pg_dump",
        "-h", config["host"],
        "-p", config["port"],
        "-U", config["user"],
        "-d", config["dbname"],
        "--clean",
        "--if-exists",
        "--no-owner",
    ]

    print(f"Backing up to {filepath} ...")
    with open(filepath, "wb") as f:
        proc = subprocess.Popen(cmd, env=env, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        gzip = subprocess.Popen(["gzip"], stdin=proc.stdout, stdout=f, stderr=subprocess.PIPE)
        _, stderr = gzip.communicate()

    if proc.returncode != 0 or gzip.returncode != 0:
        print(f"ERROR: Backup failed: {stderr.decode()}", file=sys.stderr)
        sys.exit(1)

    file_size = os.path.getsize(filepath)
    print(f"Backup complete: {filepath} ({file_size / 1024 / 1024:.1f} MB)")

    # Cleanup old backups
    cutoff = datetime.datetime.now() - datetime.timedelta(days=RETENTION_DAYS)
    removed = 0
    for fname in os.listdir(BACKUP_DIR):
        fpath = os.path.join(BACKUP_DIR, fname)
        if not os.path.isfile(fpath):
            continue
        mtime = datetime.datetime.fromtimestamp(os.path.getmtime(fpath))
        if mtime < cutoff:
            os.remove(fpath)
            removed += 1

    print(f"Cleaned up {removed} old backup(s) (retention: {RETENTION_DAYS} days)")


if __name__ == "__main__":
    main()