#!/usr/bin/env python3
"""Restore a backup to an isolated temporary database and verify its integrity."""

import argparse
import shutil
import sqlite3
import sys
import tempfile
from pathlib import Path


def main():
    parser = argparse.ArgumentParser(description="Test an Eternity Project database backup by restoring it safely.")
    parser.add_argument("backup", type=Path, help="Path to a .db backup created by backup-database.py")
    args = parser.parse_args()
    source = args.backup.resolve()
    if not source.is_file():
        print(f"BACKUP_VERIFY_FAILED: Backup does not exist: {source}", file=sys.stderr)
        return 2

    with tempfile.TemporaryDirectory(prefix="eternity-restore-") as directory:
        restored = Path(directory) / "eternity-restored.db"
        shutil.copy2(source, restored)
        try:
            database = sqlite3.connect(f"file:{restored}?mode=ro", uri=True)
            integrity = database.execute("PRAGMA integrity_check").fetchone()[0]
            users = database.execute("SELECT COUNT(*) FROM users").fetchone()[0]
            posts = database.execute("SELECT COUNT(*) FROM posts").fetchone()[0]
            database.close()
        except sqlite3.DatabaseError as error:
            print(f"BACKUP_VERIFY_FAILED: {error}", file=sys.stderr)
            return 1

    if integrity != "ok":
        print(f"BACKUP_VERIFY_FAILED: integrity_check returned {integrity}", file=sys.stderr)
        return 1
    print(f"BACKUP_RESTORE_VERIFIED: users={users} posts={posts} source={source}")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())