Koltin property delegate tools for Android SharedPreferences

SharedPreferenceManager.kt

class SharedPreferenceManager(
    val context: Context
) : SharedPreferences.OnSharedPreferenceChangeListener {

    private val sharedPreferences by lazy {
        PreferenceManager.getDefaultSharedPreferences(context)
    }
    
    private val propertyChangeListeners = hashMapOf<String, HashSet<() -> Unit>>()

    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences?, key: String?): Unit  {
        propertyChangeListeners[key]?.forEach { it() }
    }

    fun addListener(property: KProperty<*>, callback: () -> Unit) {
        propertyChangeListeners[property.name]
            .takeIf { it == null }
            .run {
                propertyChangeListeners[property.name] = HashSet()
            }


        propertyChangeListeners[property.name]?.apply {
            this.add(callback)
        }
    }

    fun removeListener(property: KProperty<*>, callback: () -> Unit) {
        propertyChangeListeners[property.name]?.apply {
            this.remove(callback)
        }
    }

    var propertyOne by sharedPreferences.stringDelegate()
    var propertyTwo by sharedPreferences.dateDelegate()
    var propertyBool by sharedPreferences.booleanDelegate(false)

}

SharedPreferencePropertyDelegate.kt

class SharedPreferencePropertyDelegate<T>(
    private val sharedPreferences: SharedPreferences,
    private val defaultValue: T,
    private val getter: SharedPreferences.(String, T) -> T,
    private val setter: SharedPreferences.Editor.(String, T) -> SharedPreferences.Editor
) : ReadWriteProperty<Any, T> {


    override fun getValue(thisRef: Any, property: KProperty<*>): T =
        sharedPreferences.getter(property.name, defaultValue)

    override fun setValue(thisRef: Any, property: KProperty<*>, value: T) =
        sharedPreferences.edit()
            .setter(property.name, value)
            .apply()
}

fun SharedPreferences.booleanDelegate(defaultValue: Boolean = false): ReadWriteProperty<Any, Boolean> =
    SharedPreferencePropertyDelegate(
        sharedPreferences = this,
        defaultValue = defaultValue,
        getter = SharedPreferences::getBoolean,
        setter = SharedPreferences.Editor::putBoolean
    )

fun SharedPreferences.intDelegate(defaultValue: Int = 0): ReadWriteProperty<Any, Int> =
    SharedPreferencePropertyDelegate(
        sharedPreferences = this,
        defaultValue = defaultValue,
        getter = SharedPreferences::getInt,
        setter = SharedPreferences.Editor::putInt
    )

fun SharedPreferences.longDelegate(defaultValue: Long = 0L): ReadWriteProperty<Any, Long> =
    SharedPreferencePropertyDelegate(
        sharedPreferences = this,
        defaultValue = defaultValue,
        getter = SharedPreferences::getLong,
        setter = SharedPreferences.Editor::putLong
    )

fun SharedPreferences.floatDelegate(defaultValue: Float = 0f): ReadWriteProperty<Any, Float> =
    SharedPreferencePropertyDelegate(
        sharedPreferences = this,
        defaultValue = defaultValue,
        getter = SharedPreferences::getFloat,
        setter = SharedPreferences.Editor::putFloat
    )

fun SharedPreferences.stringDelegate(defaultValue: String? = null): ReadWriteProperty<Any, String?> =
    SharedPreferencePropertyDelegate(
        sharedPreferences = this,
        defaultValue = defaultValue,
        getter = SharedPreferences::getString,
        setter = SharedPreferences.Editor::putString
    )

fun SharedPreferences.getDate(key: String, defaultValue: Date? = null): Date? =
    getLong(key, -1).let {
        if (it >= 0) Date(it) else defaultValue
    }

fun SharedPreferences.Editor.putDate(key: String, value: Date? = null): SharedPreferences.Editor =
    if (value != null) {
        putLong(key, value.time)
    } else {
        remove(key)
    }

fun SharedPreferences.dateDelegate(defaultValue: Date? = null): ReadWriteProperty<Any, Date?> {
    return SharedPreferencePropertyDelegate(
        sharedPreferences = this,
        defaultValue = defaultValue,
        getter = SharedPreferences::getDate,
        setter = SharedPreferences.Editor::putDate
    )
}