app/utils/neo4j_utils.py

# app/utils/neo4j_utils.py (Corrected Import)

import logging
# --- MODIFICATION HERE ---
# Import base components from neo4j
from neo4j import AsyncGraphDatabase, AsyncDriver
# Import specific error class from neo4j.exceptions
from neo4j.exceptions import Neo4jError
# --- END MODIFICATION ---
from typing import Optional

# Import settings for credentials
from app.core.config import settings

logger = logging.getLogger(__name__)

# Global variable to hold the driver instance (singleton pattern)
_driver: Optional[AsyncDriver] = None

async def get_driver() -> Optional[AsyncDriver]:
    """
    Initializes and returns the singleton Neo4j AsyncDriver instance.
    Reads credentials from settings. Returns None on failure.
    """
    global _driver
    if _driver is None:
        uri = settings.NEO4J_URI
        username = settings.NEO4J_USERNAME
        password = settings.NEO4J_PASSWORD

        if not uri or not username or not password:
            logger.error("Neo4j connection details (URI, USERNAME, PASSWORD) missing in configuration.")
            return None

        logger.info(f"Initializing Neo4j Async Driver for URI: {uri}")
        try:
            _driver = AsyncGraphDatabase.driver(uri, auth=(username, password))
            await _driver.verify_connectivity()
            logger.info("Neo4j Driver initialized and connection verified.")
        # --- MODIFICATION HERE: Catch the correctly imported Neo4jError ---
        except Neo4jError as e:
        # --- END MODIFICATION ---
            logger.exception(f"Failed to initialize Neo4j Driver or verify connection: {e.message} (code: {e.code})")
            _driver = None
        except Exception as e:
            logger.exception(f"An unexpected error occurred during Neo4j Driver initialization: {e}")
            _driver = None

    return _driver

async def close_driver():
    """Closes the Neo4j AsyncDriver connection if it exists."""
    global _driver
    if _driver is not None:
        logger.info("Closing Neo4j Async Driver...")
        try:
            await _driver.close()
            _driver = None
            logger.info("Neo4j Driver closed successfully.")
        except Exception as e:
            logger.exception(f"Error closing Neo4j Driver: {e}")

# Optional: Dependency for API endpoints if needed later
# ... (keep commented out for now) ...