database.py

import firebase_admin
from firebase_admin import credentials
from firebase_admin import firestore
from vars import FIREBASE_CREDENTIALS_FILE


class FirestoreDB:
    _instance = None  # Class attribute to hold the single instance

    def __new__(cls):
        """Override __new__ to control the creation of new instances."""
        if cls._instance is None:
            cls._instance = super(FirestoreDB, cls).__new__(cls)
            cls._initialize(cls._instance)
        return cls._instance

    @classmethod
    def _initialize(cls, instance):
        """Initialize the single instance."""
        cred = credentials.Certificate(FIREBASE_CREDENTIALS_FILE)
        firebase_admin.initialize_app(cred)
        instance.db = firestore.client()

    def save_data(self, collection, document_id, data):
        """Save data to the specified Firestore collection."""
        doc_ref = self.db.collection(collection).document(document_id)
        doc_ref.set(data)

    def get_data(self, collection, field=None, limit=None, descending=True):
        """Retrieve data from the specified Firestore collection with optional sorting and limiting."""
        query = self.db.collection(collection)
        if field:
            query = query.order_by(
                field, direction=firestore.Query.DESCENDING if descending else firestore.Query.ASCENDING)
        if limit:
            query = query.limit(limit)
        docs = query.stream()
        return {doc.id: doc.to_dict() for doc in docs}