from flask import g
from pymongo import MongoClient
from .config import settings


def connect_db():
    """
    Creates the connection to the MongoDB using the config file data.
    Thos function is used by flask application as well as the scraper script

    :return: connection to the collection in the mongodb
    """
    client = MongoClient(settings["mongodb_uri"])
    db = client[settings["mongodb_db"]]
    collection = db[settings["mongodb_collection"]]
    return collection


def disconnect_db(conn):
    """
    Disconnects open connection
    :param conn: open db connection
    """
    conn.database.client.close()


def get_db():
    """
    Get collection instance for flask application. If no instance stored in global variables, then create connection
    and store it in g
    """
    collection = getattr(g, "_database", None)

    if collection is None:
        collection = g._database = connect_db()

    return collection