// Next.js API route support: https://nextjs.org/docs/api-routes/introduction
import type {NextApiRequest, NextApiResponse} from "next";
import {app} from "@/firebase";
import {getFirestore, collection, getDocs, query, where} from "firebase/firestore";
import {withIronSessionApiRoute} from "iron-session/next";
import {sessionOptions} from "@/lib/session";
import {shuffle} from "lodash";
import {Exam} from "@/interfaces/exam";
import {Stat} from "@/interfaces/user";

const db = getFirestore(app);

export default withIronSessionApiRoute(handler, sessionOptions);

async function handler(req: NextApiRequest, res: NextApiResponse) {
	if (!req.session.user) {
		res.status(401).json({ok: false});
		return;
	}

	const {module, avoidRepeated} = req.query as {module: string; avoidRepeated: string};
	const moduleRef = collection(db, module);

	const q = query(moduleRef, where("isDiagnostic", "==", true));
	const snapshot = await getDocs(q);

	const exams: Exam[] = shuffle(
		snapshot.docs.map((doc) => ({
			id: doc.id,
			...doc.data(),
			module,
		})),
	) as Exam[];

	if (avoidRepeated === "true") {
		const statsQ = query(collection(db, "stats"), where("user", "==", req.session.user.id));
		const statsSnapshot = await getDocs(statsQ);

		const stats: Stat[] = statsSnapshot.docs.map((doc) => ({id: doc.id, ...doc.data()})) as unknown as Stat[];
		const filteredExams = exams.filter((x) => !stats.map((s) => s.exam).includes(x.id));

		res.status(200).json(filteredExams.length > 0 ? filteredExams : exams);
		return;
	}

	res.status(200).json(exams);
}