import { PostgreSQLClient } from './client';
import type { PostgreSQLClientConfig } from './types';

/**
 * Singleton PostgreSQL client instance
 * Provides global access to a single PostgreSQL connection pool
 */
let instance: PostgreSQLClient | null = null;

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

/**
 * Get the singleton PostgreSQL client instance
 * @throws Error if not initialized
 */
export function getPostgreSQLClient(): PostgreSQLClient {
  if (!instance) {
    throw new Error('PostgreSQL client not initialized. Call connectPostgreSQL(config) first.');
  }
  return instance;
}

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

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