import { MongoClient, Db } from 'mongodb';
import { createLogger } from './logger';

const log = createLogger("db:client");

let client: MongoClient | null = null;
let db: Db | null = null;

/**
 * Connect to MongoDB
 * @returns Database instance
 */
export async function connectToDatabase(): Promise<Db> {
    if (!process.env.MONGODB_URI) {
        throw new Error('MONGODB_URI environment variable is not set');
    }

    if (db) {
        log('Reusing existing database connection');
        return db;
    }

    log('Creating new database connection');
    client = new MongoClient(process.env.MONGODB_URI);
    await client.connect();
    db = client.db("utility-bills");

    log('Connected to database');
    return db;
}

/**
 * Disconnect from MongoDB
 */
export async function disconnectFromDatabase(): Promise<void> {
    if (client) {
        log('Disconnecting from database');
        await client.close();
        client = null;
        db = null;
        log('Disconnected from database');
    }
}

/**
 * Get current database instance (must call connectToDatabase first)
 */
export function getDatabase(): Db {
    if (!db) {
        throw new Error('Database not connected. Call connectToDatabase() first.');
    }
    return db;
}