'use strict';

require('dotenv').config();

const { MongoClient } = require('mongodb');

let client;

let connectionPromise;

async function getDatabase() {

if (!process.env.MONGODB_URI) {

throw new Error('MONGODB_URI is required to connect to MongoDB.');

}

if (!connectionPromise) {

try {

client = new MongoClient(process.env.MONGODB_URI);

} catch {

throw new Error(

'MongoDB connection failed. MONGODB_URI must be a valid MongoDB connection string.',

);

}

const connectingClient = client;

connectionPromise = connectingClient.connect()

.then(() => {

const database = connectingClient.db();

return {

database,

subscribers: database.collection('subscribers'),

reminders: database.collection('reminders'),

checkins: database.collection('checkins'),

};

})

.catch(() => {

client = undefined;

connectionPromise = undefined;

throw new Error(

'MongoDB connection failed. Check MONGODB_URI, Atlas network access, and database credentials.',

);

});

}

return connectionPromise;

}

async function closeDatabase() {

if (client) {

const connectedClient = client;

client = undefined;

connectionPromise = undefined;

await connectedClient.close();

}

}

module.exports = getDatabase;

module.exports.close = closeDatabase;