Added the ability for a user to select to avoid repeated exams

src/pages/api/exam/[module]/index.ts

@@ -5,6 +5,8 @@ import {getFirestore, collection, getDocs, query, where} from "firebase/firestor
 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);
 
@@ -18,17 +20,28 @@ async function handler(req: NextApiRequest, res: NextApiResponse) {
 
 	const {module, avoidRepeated} = req.query as {module: string; avoidRepeated: string};
 	const moduleRef = collection(db, module);
-	const q = query(moduleRef, where("isDiagnostic", "==", false));
 
+	const q = query(moduleRef, where("isDiagnostic", "==", false));
 	const snapshot = await getDocs(q);
 
-	res.status(200).json(
-		shuffle(
-			snapshot.docs.map((doc) => ({
-				id: doc.id,
-				...doc.data(),
-				module,
-			})),
-		),
-	);
+	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);
 }