import { MongoClient } from "mongodb";

/**
 * Lazy MongoClient promise. We don't touch `process.env.MONGODB_URI` at module
 * import time so `next build` / page-data collection doesn't crash when the env
 * isn't populated (e.g. inside a Docker build with no runtime env).
 */

declare global {
  var _mongoClientPromise: Promise<MongoClient> | undefined;
}

function createClientPromise(): Promise<MongoClient> {
  const uri = process.env.MONGODB_URI;
  if (!uri) {
    throw new Error("MONGODB_URI is not set");
  }
  const client = new MongoClient(uri, {});
  return client.connect();
}

function getClientPromise(): Promise<MongoClient> {
  if (process.env.NODE_ENV === "development") {
    if (!globalThis._mongoClientPromise) {
      globalThis._mongoClientPromise = createClientPromise();
    }
    return globalThis._mongoClientPromise;
  }
  if (!globalThis._mongoClientPromise) {
    globalThis._mongoClientPromise = createClientPromise();
  }
  return globalThis._mongoClientPromise;
}

const clientPromise: Promise<MongoClient> = {
  then: (onFulfilled, onRejected) => getClientPromise().then(onFulfilled, onRejected),
  catch: (onRejected) => getClientPromise().catch(onRejected),
  finally: (onFinally) => getClientPromise().finally(onFinally),
  [Symbol.toStringTag]: "Promise",
} as Promise<MongoClient>;

export default clientPromise;