dManufacturer = "Hyundai"
dModel = "Kona"
dTopSpeed ="150"
Map<String, Object> car = new HashMap<>();
car.put("manufacturer", dManufacturer);
car.put("model", dModel);
car.put("top_speed",dTopSpeed);


db.collection(cars")
.add(car)
.addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
 @Override
 public void onSuccess(DocumentReference documentReference) {
 Log.d("firebaseab", "DocumentSnapshot added with ID: " + documentReference.getId());
 }
})
.addOnFailureListener(new OnFailureListener() {
 @Override
 public void onFailure(@NonNull Exception e) {
 Log.w("firebaseab", "Error adding document", e);
 }
});

service cloud.firestore {
  match /databases/{database}/documents {
    match /{document=**} {
      allow read;
    }
    // match /{document=**} {
    //   //allow create: if document != request.resource.data;
    //   allow create: if document.manufacturer == "Google";
    // }
    match /cars/{car} {
      allow create : if request.resource.data.manufacturer != resource.data.manufacturer
                    && request.resource.data.model != resource.data.model
                    && request.resource.data.topSpeed != resource.data.topSpeed;

    }
  }
}