// Next.js API route support: https://nextjs.org/docs/api-routes/introduction
import type { NextApiRequest, NextApiResponse } from "next";
import { app } from "@/firebase";
import {
  getFirestore,
  setDoc,
  doc,
  runTransaction,
  collection,
  query,
  where,
  getDocs,
} from "firebase/firestore";
import { withIronSessionApiRoute } from "iron-session/next";
import { sessionOptions } from "@/lib/session";
import { Exam, InstructorGender, Variant } from "@/interfaces/exam";
import { getExams } from "@/utils/exams.be";
import { Module } from "@/interfaces";
const db = getFirestore(app);

export default withIronSessionApiRoute(handler, sessionOptions);

async function handler(req: NextApiRequest, res: NextApiResponse) {
  if (req.method === "GET") return await GET(req, res);
  if (req.method === "POST") return await POST(req, res);

  res.status(404).json({ ok: false });
}

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

  const { module, avoidRepeated, variant, instructorGender } = req.query as {
    module: Module;
    avoidRepeated: string;
    variant?: Variant;
    instructorGender?: InstructorGender;
  };

  const exams: Exam[] = await getExams(
    db,
    module,
    avoidRepeated,
    req.session.user.id,
    variant,
    instructorGender
  );
  res.status(200).json(exams);
}

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

  if (req.session.user.type !== "developer") {
    res.status(403).json({ ok: false });
    return;
  }
  const { module } = req.query as { module: string };

  try {
    const exam = {
      ...req.body,
      module: module,
      createdBy: req.session.user.id,
      createdAt: new Date().toISOString(),
    };
    await runTransaction(db, async (transaction) => {
      const docRef = doc(db, module, req.body.id);
      const docSnap = await transaction.get(docRef);

      if (docSnap.exists()) {
        throw new Error("Name already exists");
      }

      const newDocRef = doc(db, module, req.body.id);
      transaction.set(newDocRef, exam);
    });
    res.status(200).json(exam);
  } catch (error) {
    console.error("Transaction failed: ", error);
    res.status(500).json({ ok: false, error: (error as any).message });
  }
}