app/db.py

from motor.motor_asyncio import AsyncIOMotorClient
from pydantic import BaseModel, Field
from pydantic_core import CoreSchema, PydanticCustomError, core_schema
import os
from dotenv import load_dotenv

# Load environment variables from .env file
load_dotenv()

# --- Configuration ---
# Example: MONGODB_URI = "mongodb+srv://<user>:<password>@cluster0.xyz.mongodb.net/"
MONGODB_URI = os.getenv("MONGODB_URI", "")
DB_NAME = "hf_masala_barcodes"


# --- Database Client ---
client = AsyncIOMotorClient(MONGODB_URI)
db = client[DB_NAME]  # Database: hf_masala_barcodes

# --- Collections ---
# We access the database collections here
user_collection = db.get_collection("users")
sku_collection = db.get_collection("skus")


# This helps FastAPI validate data from MongoDB and is now fully V2 compliant.
class PyObjectId(str):
    """Custom type to handle MongoDB ObjectId for Pydantic V2.
    It serializes MongoDB ObjectIds (or their string representations) as strings 
    for JSON serialization and validation.
    """
    @classmethod
    def __get_pydantic_core_schema__(cls, source_type, handler) -> CoreSchema:
        
        # Define the validation logic
        def validate_object_id(value):
            """Converts the input (e.g., an ObjectId object) into a string."""
            try:
                # We return the string representation of the ID
                return str(value)
            except Exception:
                raise PydanticCustomError('invalid_objectid', 'ObjectId or string representation required')

        # Fix: Changed core_schema.string_schema() to core_schema.str_schema()
        string_schema = core_schema.str_schema()
        
        # Define the core schema for the type
        return core_schema.json_or_python_schema(
            json_schema=string_schema,
            python_schema=core_schema.chain_schema([
                # Accept any type (e.g., a bson.ObjectId instance)
                core_schema.any_schema(), 
                # Use our custom validator function
                core_schema.no_info_plain_validator_function(validate_object_id),
            ]),
            # Ensure the final output (for serialization) is a string
            serialization=core_schema.to_string_ser_schema(),
        )