/*
 * Copyright The WildFly Authors
 * SPDX-License-Identifier: Apache-2.0
 */

package org.wildfly.clustering.marshalling.protostream;

import java.io.IOException;

import org.infinispan.protostream.descriptors.WireType;

/**
 * ProtoStream marshaller for enums.
 * @author Paul Ferraro
 * @param <E> the enum type of this marshaller
 */
public class EnumMarshaller<E extends Enum<E>> implements org.infinispan.protostream.EnumMarshaller<E>, ProtoStreamMarshaller<E> {
	// Optimize for singleton enums
	private static final int DEFAULT_ORDINAL = 0;

	private static final int ORDINAL_INDEX = 1;

	private final Class<E> enumClass;
	private final E[] values;

	EnumMarshaller(Class<E> enumClass) {
		this.enumClass = enumClass;
		this.values = enumClass.getEnumConstants();
	}

	@Override
	public Class<? extends E> getJavaClass() {
		return this.enumClass;
	}

	@Override
	public E decode(int ordinal) {
		return this.values[ordinal];
	}

	@Override
	public int encode(E value) {
		return value.ordinal();
	}

	@Override
	public E readFrom(ProtoStreamReader reader) throws IOException {
		E result = this.values[DEFAULT_ORDINAL];
		while (!reader.isAtEnd()) {
			int tag = reader.readTag();
			switch (WireType.getTagFieldNumber(tag)) {
				case ORDINAL_INDEX:
					result = reader.readEnum(this.enumClass);
					break;
				default:
					reader.skipField(tag);
			}
		}
		return result;
	}

	@Override
	public void writeTo(ProtoStreamWriter writer, E value) throws IOException {
		if (value.ordinal() != DEFAULT_ORDINAL) {
			writer.writeEnum(ORDINAL_INDEX, value);
		}
	}
}
