import pymongo
import urllib.parse
import os

def create_db():
    """
    Connect to MongoDB Atlas and create collections for the Billing App.
    """

    raw_username = os.getenv("DB_USERNAME")
    raw_password = os.getenv("DB_PASSWORD")

    if not raw_username or not raw_password:
        raise Exception("Database credentials are missing. Check your environment variables.")
    cluster = "cluster0"  

    username = urllib.parse.quote_plus(raw_username)
    password = urllib.parse.quote_plus(raw_password)

    uri = f"mongodb+srv://{username}:{password}@cluster0.yxjok.mongodb.net/?retryWrites=true&w=majority&appName=Cluster0"

    client = pymongo.MongoClient(uri)

    db = client["billing_app"]

    users_coll = db["users"]
    sections_coll = db["sections"]
    bills_coll = db["bills"]

    users_coll.create_index("email", unique=True)
    sections_coll.create_index(
        [("owner_email", 1), ("section_name", 1)],
        unique=True
    )
    bills_coll.create_index(
        [("owner_email", 1), ("section_name", 1), ("participant", 1)]
    )

    print("Database and collections created (or already exist). Indexes applied.")

if __name__ == "__main__":
    create_db()