PhysiGo/app/lib/challenges/challenges_utils.dart

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:geoflutterfire/geoflutterfire.dart';
import 'dart:math';

class ChallengesUtils {
  static final geo = Geoflutterfire();
  static final _firestore = FirebaseFirestore.instance;

  static Future<DocumentSnapshot<Map<String, dynamic>>> getChallenge() async {
    Future<DocumentSnapshot<Map<String, dynamic>>> challenge;
    if (await shouldGenerateChallenge()) {
      challenge = generateChallenge();
    } else {
      final user = _firestore.collection('Users').doc('tlmysIvwTBaoZKWqBofx');
      challenge = user.get().then((value) => value.get('weekly_place').get());
    }
    return challenge;
  }

  static Future<bool> shouldGenerateChallenge() async {
    final user = _firestore.collection('Users').doc('tlmysIvwTBaoZKWqBofx');
    DateTime now = DateTime.now();
    DateTime today = DateTime(now.year, now.month, now.day);
    DateTime lastMonday = today.subtract(Duration(days: today.weekday - 1));
    int secondsSinceEpoch = lastMonday.millisecondsSinceEpoch ~/ 1000;
    bool shouldGenerate = await user.get().then((value) {
      final dif = secondsSinceEpoch - value.get('last_challenge_date').seconds;
      return dif / 3600 / 24 > 7;
    });
    return Future.value(shouldGenerate);
  }

  static Future<DocumentSnapshot<Map<String, dynamic>>> generateChallenge() async {
    final user = await _firestore.collection('Users').doc('tlmysIvwTBaoZKWqBofx').get();
    Query<Map<String, dynamic>> places = _firestore.collection('Places');
    double innerRadius = 3;
    double outerRadius = 5;
    String randomPlaceID = '';

    Stream<List<DocumentSnapshot>> possiblePlaces = geo.collection(collectionRef: places).within(
        center: geo.point(latitude: user.get('address').latitude, longitude: user.get('address').longitude),
        radius: outerRadius,
        field: 'location',
        strictMode: true);

    Stream<List<DocumentSnapshot>> placesTooClose = geo.collection(collectionRef: places).within(
        center: geo.point(latitude: user.get('address').latitude, longitude: user.get('address').longitude),
        radius: innerRadius,
        field: 'location',
        strictMode: true);

    List<DocumentSnapshot<Object?>> possiblePlacesList = await possiblePlaces.first;
    List<DocumentSnapshot<Object?>> placesTooCloseList = await placesTooClose.first;
    final ids = <String>{};
    for (DocumentSnapshot<Object?> element in placesTooCloseList) {
      ids.add(element.id);
    }
    possiblePlacesList.retainWhere((element) => !ids.contains(element.id));
    int numOfPlaces = possiblePlacesList.length;
    randomPlaceID = possiblePlacesList[Random().nextInt(numOfPlaces)].id;
    _firestore.collection('Users').doc('tlmysIvwTBaoZKWqBofx').update({
      'weekly_place': _firestore.collection('Places').doc(randomPlaceID),
      'last_challenge_date': Timestamp.now(),
    });
    return _firestore.collection('Places').doc(randomPlaceID).get();
  }
}