import { MongoClient, Db } from "mongodb";
import Redis from "redis";

let db: Db;

export default async function buildDBClient(): Promise<Db> {
	if (db) return db;
	const url = getDBUrl();
	const client = new MongoClient(url);
	try {
		await client.connect();
		db = client.db();
		console.info("Connected successfully to MongoDB");
		return db;
	} catch (error) {
		console.error(`Failed to connect to MongoDB: ${error}`);
		throw error;
	}
}

const redis = Redis.createClient({ url: process.env["REDIS_URL"] });

export { redis, db };

// Checks if all required env vars were supplied, and returns the mongo db URL
function getDBUrl(): string {
	const env = process.env;
	if (env["DB_URL"]) return env["DB_URL"];

	if (!env["DB_HOST"]) {
		console.error(`Environment variable 'DB_HOST' not set, unable to connect to database`);
		console.error(`Specify either 'DB_URL' or 'DB_HOST', 'DB_USERNAME', 'DB_PASS' and 'DB_NAME'`);
		throw new Error("Missing environment variables");
	}

	// mongodb://username:password@hostname:port/dbname
	let dburl = "mongodb://";
	if (env["DB_USERNAME"]) dburl += env["DB_USERNAME"];
	if (env["DB_PASS"]) dburl += `:${env["DB_PASS"]}`;
	dburl += `${env["DB_USERNAME"] ? "@" : ""}${env["DB_HOST"]}`; // DB_HOST is assumed to contain the port
	dburl += `/${env["DB_NAME"] ?? "automod"}`;
	return dburl;
}