feat(DB): implement function to update user saved place address

Author: ZhiXin18

lib/utilities/firebase_calls.dart

@@ -0,0 +1,40 @@
+import 'package:firebase_auth/firebase_auth.dart';
+import 'package:cloud_firestore/cloud_firestore.dart';
+
+FirebaseAuth auth = FirebaseAuth.instance;
+CollectionReference usersCollection =
+    FirebaseFirestore.instance.collection('users');
+CollectionReference congestionCollection =
+    FirebaseFirestore.instance.collection('congestions');
+bool newUser = true;
+
+class FirebaseCalls {
+  Future<void> updateUser(String username, List<Map<String, dynamic>> addresses) async {
+    // Fetch the currently authenticated user
+    User? currentUser = auth.currentUser;
+
+    // Ensure that the user is logged in
+    if (currentUser == null) {
+      throw Exception("No user is logged in.");
+    }
+
+    // Check if there is an existing record of user
+    QuerySnapshot querySnap = await usersCollection.where('userid', isEqualTo: currentUser.uid).get();
+
+    if (querySnap.docs.isNotEmpty) {
+      // Existing user
+      QueryDocumentSnapshot doc = querySnap.docs[0];
+      await doc.reference.update({
+        'addresses': addresses,
+      });
+    } else {
+      // New user
+      await usersCollection.add({
+        'addresses': addresses,
+        'username': username,
+        'userid': currentUser.uid,
+      });
+    }
+  }
+}
+