[Catalyst] Clean up SharedPreferencesObservable

/*

 * Copyright (C) 2024 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.android.settingslib.datastore

import android.content.SharedPreferences

/** [SharedPreferences] based [KeyedDataObservable]. */

class SharedPreferencesObservable(private val sharedPreferences: SharedPreferences) :

    KeyedDataObservable<String>(), AutoCloseable {

    private val listener = createSharedPreferenceListener()

    init {

        sharedPreferences.registerOnSharedPreferenceChangeListener(listener)

    }

    override fun close() {

        sharedPreferences.unregisterOnSharedPreferenceChangeListener(listener)

    }

}

/** Creates [SharedPreferences.OnSharedPreferenceChangeListener] for [KeyedObservable]. */

internal fun KeyedObservable<String>.createSharedPreferenceListener() =

    SharedPreferences.OnSharedPreferenceChangeListener { _, key ->

        if (key != null) {

            notifyChange(key, DataChangeReason.UPDATE)

        } else {

            // On Android >= R, SharedPreferences.Editor.clear() will trigger this case

            notifyChange(DataChangeReason.DELETE)

        }

    }