import json
import sys
import datetime
import logging
from pymongo import MongoClient, errors

# Setup logging configuration
logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s - %(levelname)s - %(message)s',
    handlers=[
        logging.StreamHandler(sys.stdout),
        # logging.FileHandler("mongo_cleanup.log") # Uncomment to log to a file
    ]
)
logger = logging.getLogger(__name__)

def load_config(config_path):
    """Loads configuration from a JSON file."""
    try:
        with open(config_path, "r", encoding="utf-8") as f:
            return json.load(f)
    except FileNotFoundError:
        logger.warning(f"'{config_path}' file not found. Using defaults/environment variables if available.")
        return {}
    except Exception as e:
        logger.critical(f"Failed to load config: {e}")
        sys.exit(1)

def delete_old_documents(mongo_uri, db_name, collection_name, days_threshold):
    client = None
    try:
        # Validation
        if days_threshold is None:
            raise ValueError("DAYS_THRESHOLD configuration is missing or None.")

        # 1. Connect to MongoDB
        logger.info(f"Connecting to MongoDB at {mongo_uri}...")
        client = MongoClient(mongo_uri, serverSelectionTimeoutMS=5000)
        
        # Check connection
        client.admin.command('ping')
        logger.info("Connected successfully.")

        db = client[db_name]
        collection = db[collection_name]
        
        # 2. Calculate the cutoff date (Using UTC for consistency)
        # We explicitly cast to int to prevent type errors
        cutoff_date = datetime.datetime.now(datetime.timezone.utc) - datetime.timedelta(days=int(days_threshold))
        
        logger.info(f"Targeting documents created before: {cutoff_date} (UTC)")

        # 3. Define the query
        # Using "Timestamp" as requested. Ensure this matches your DB schema.
        query = {"Timestamp": {"$lt": cutoff_date}}

        # 4. Perform the deletion
        logger.info(f"Executing delete query on {db_name}.{collection_name}...")
        result = collection.delete_many(query)

        logger.info(f"Operation complete. Deleted {result.deleted_count} documents.")

    except errors.ServerSelectionTimeoutError:
        logger.error("Could not connect to MongoDB. Check URI and network status.")
    except errors.PyMongoError as e:
        logger.error(f"MongoDB error occurred: {e}")
    except ValueError as ve:
        logger.error(f"Configuration error: {ve}")
    except Exception as e:
        logger.error(f"An unexpected error occurred: {e}")
    finally:
        # Close the connection
        if client:
            client.close()
            logger.debug("MongoDB connection closed.")

if __name__ == "__main__":
    GLOBAL_CONFIG_PATH = "config.json"
    
    # Load Configuration
    config = load_config(GLOBAL_CONFIG_PATH)
    
    # --- CONFIGURATION ---
    MONGODB_CONFIG = config.get("MONGODB", {})
    
    # Use .get() with defaults for safety
    MONGO_URI = MONGODB_CONFIG.get("MONGO_CONNECTION_STRING", "mongodb://localhost:27017/")
    DB_NAME = MONGODB_CONFIG.get("DATABASE_NAME", "DotNetLogsProd")
    COLLECTION_NAME = MONGODB_CONFIG.get("COLLECTION_NAME", "api-logs")
    
    # Days to keep (anything older than this gets deleted)
    # Checking root level as per your snippet
    DAYS_THRESHOLD = config.get("DAYS_THRESHOLD")
    
    # Fallback: If DAYS_THRESHOLD is missing in config, prevent the NoneType error
    if DAYS_THRESHOLD is None:
        logger.warning("DAYS_THRESHOLD not found in config. Defaulting to 30 days.")
        DAYS_THRESHOLD = 30
    # ---------------------

    # Pass configuration as arguments
    delete_old_documents(MONGO_URI, DB_NAME, COLLECTION_NAME, DAYS_THRESHOLD)