generic enum kserializer for kotlinx.serialization

EnumSerializer.kt

abstract class EnumSerializer<T : Enum<T>>(values: Array<out T>, private val defaultValue: T) : KSerializer<T> {

    private val lookup = values.associateBy({ it }, { it.serialName })
    private val revLookup = values.associateBy { it.serialName.uppercase() }

    override val descriptor = PrimitiveSerialDescriptor(values.first()::class.qualifiedName!!, PrimitiveKind.STRING)
    
    override fun serialize(encoder: Encoder, value: T) = encoder.encodeString(lookup.getValue(value))

    override fun deserialize(decoder: Decoder) = revLookup[decoder.decodeString().uppercase()] ?: defaultValue

    private val Enum<T>.serialName: String
        get() = this::class.java.getField(this.name).getAnnotation(SerialName::class.java)?.value ?: name
}

// Usage example
@Serializable(with = PrioritySerializer::class)
enum class Priority {
    @SerialName("highest")
    HIGH,
    MEDIUM,
    LOW,
    NO_PRIORITY
}
object PrioritySerializer : EnumSerializer<Priority>(values = Priority.values(), defaultValue = Priority.NO_PRIORITY)