uploadProfilePicture

    private fun uploadProfilePicture(profilePicture: Bitmap, callback: (Exception?, Uri?) -> Unit) {
        Log.v("STORAGE", "Uploading a profile picture")
        val baos = ByteArrayOutputStream()
        val storage = FirebaseStorage.getInstance()

        val filePath = "profilePictures/${auth.currentUser!!.uid}"

        val storageRef = storage
                .reference
                .child(filePath)
        profilePicture.compress(Bitmap.CompressFormat.JPEG, 100, baos)
        val img = baos.toByteArray()

        storageRef.putBytes(img).let {
            it.continueWithTask { task ->
                if (!task.isSuccessful) {
                    task.exception?.let { e ->
                        callback(e, null)
                    }
                }
                storageRef.downloadUrl
            }.addOnCompleteListener{ task ->
                if (task.isSuccessful) {
                    Log.v("STORAGE", "Profile picture upload successful")
                    callback(null, task.result)
                } else {
                    Log.e("STORAGE", "Profile picture upload failed")
                    callback(task.exception, null)
                }
            }
        }
    }