from pymongo import MongoClient
from dotenv import load_dotenv
import logging
import os


def connect():
    """Connect to MongoDB."""
    # load env vars
    load_dotenv()
    necessary_env_vars = [
        "MONGO_HOST",
        "MONGO_DB",
        "MONGO_COLLECTION"
    ]
    for env_var in necessary_env_vars:
        assert env_var in os.environ, f"{env_var} not found"
    # connect to database
    client = MongoClient(os.getenv("MONGO_HOST"))
    db = client[os.getenv("MONGO_DB")]
    collection = db[os.getenv("MONGO_COLLECTION")]
    collection.create_index("name", unique=True)
    logging.info("connected to database")
    return collection, db, client