import { MongoDBClient } from './client';
import type { MongoDBClientConfig } from './types';
import type { Db } from 'mongodb';

/**
 * Singleton MongoDB client instance
 * Provides global access to a single MongoDB connection
 */
let instance: MongoDBClient | null = null;

/**
 * Initialize the singleton MongoDB client
 */
export async function connectMongoDB(config?: MongoDBClientConfig): Promise<MongoDBClient> {
  if (!instance) {
    if (!config) {
      throw new Error('MongoDB client not initialized. Call connectMongoDB(config) first.');
    }
    instance = new MongoDBClient(config);
    await instance.connect();
  }
  return instance;
}

/**
 * Get the singleton MongoDB client instance
 * @throws Error if not initialized
 */
export function getMongoDBClient(): MongoDBClient {
  if (!instance) {
    throw new Error('MongoDB client not initialized. Call connectMongoDB(config) first.');
  }
  return instance;
}

/**
 * Get the MongoDB database instance
 * @throws Error if not initialized
 */
export function getDatabase(): Db {
  if (!instance) {
    throw new Error('MongoDB client not initialized. Call connectMongoDB(config) first.');
  }
  return instance.getDatabase();
}

/**
 * Check if the MongoDB client is initialized
 */
export function isInitialized(): boolean {
  return instance !== null && instance.connected;
}

/**
 * Disconnect and reset the singleton instance
 */
export async function disconnectMongoDB(): Promise<void> {
  if (instance) {
    await instance.disconnect();
    instance = null;
  }
}