import {VercelRequest, VercelResponse} from '@vercel/node';
import {initializeApp, cert} from 'firebase-admin/app';
import {getFirestore} from 'firebase-admin/firestore';
import {firestore} from "firebase-admin";
import Timestamp = firestore.Timestamp;


export default async function generateChallenge(req: VercelRequest, res: VercelResponse) {
    const type = req.query.type;
    const serviceAccountStringified = Buffer.from(process.env.FIREBASE_SERVICE_ACCOUNT!, 'base64').toString('ascii');
    const serviceAccount = JSON.parse(serviceAccountStringified);
    initializeApp({
        credential: cert(serviceAccount)
    });

    const firestore = getFirestore();
    const challengeRef = type === 'daily' ? firestore.collection('DailyChallenges') :
        firestore.collection('WeeklyChallenges');

    if (type === 'daily') {
        // @ts-ignore
        const yesterday = new Date(new Date() - 1000 * 3600 * 22);

        const todayChallenge = await challengeRef.where('date', '>', yesterday).get();

        if (!todayChallenge.empty) {
            res.json({
                message: `challenge for ${new Date()} is already generated`,
            })
        }
    } else if (type === 'weekly') {
        // @ts-ignore
        const weekAgo = new Date(new Date() - 1000 * 3600 * 24 * 7 - 3600);

        const thisWeekChallenge = await challengeRef.where('date', '>', weekAgo).get();

        if (!thisWeekChallenge.empty) {
            res.json({
                message: 'challenge for this week already exists',
                date: new Date(),
            });
        }
    }

    const exercisesSnapshot = await firestore.collection('Exercises').get();
    const exercises: FirebaseFirestore.DocumentData[] = [];
    exercisesSnapshot.forEach((exercise) => {
        exercises.push(firestore.collection('Exercises').doc(exercise.id));
    });
    const shuffled = exercises.sort(() => 0.5 - Math.random());
    const selected = shuffled.slice(0, 3);
    const bonus = exercises[Math.floor(Math.random() * exercises.length)];

    const firestoreRes = await challengeRef.add({
        date: Timestamp.fromDate(new Date()),
        list_exercises: selected,
        bonus_exercise: bonus,
    });
    res.json(firestoreRes);
}