/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.lang3;

import java.util.HashMap;
import java.util.Map;
import java.util.stream.Stream;

import org.apache.commons.lang3.arch.Processor;

/**
 * An utility class for the os.arch System Property. The class defines methods
 * for identifying the architecture of the current JVM.
 * <p>
 * Important: The os.arch System Property returns the architecture used by the
 * JVM not of the operating system.
 * </p>
 * 
 * @since 3.6
 */
public class ArchUtils {

	private static final Map<String, Processor> ARCH_TO_PROCESSOR;

	static {
		ARCH_TO_PROCESSOR = new HashMap<>();
		init();
	}

	private static void init() {
		init_X86_32Bit();
		init_X86_64Bit();
		init_IA64_32Bit();
		init_IA64_64Bit();
		init_PPC_32Bit();
		init_PPC_64Bit();
	}

	private static void init_X86_32Bit() {
		final Processor processor = new Processor(Processor.Arch.BIT_32, Processor.Type.X86);
		addProcessors(processor, "x86", "i386", "i486", "i586", "i686", "pentium");
	}

	private static void init_X86_64Bit() {
		final Processor processor = new Processor(Processor.Arch.BIT_64, Processor.Type.X86);
		addProcessors(processor, "x86_64", "amd64", "em64t", "universal");
	}

	private static void init_IA64_32Bit() {
		final Processor processor = new Processor(Processor.Arch.BIT_32, Processor.Type.IA_64);
		addProcessors(processor, "ia64_32", "ia64n");
	}

	private static void init_IA64_64Bit() {
		final Processor processor = new Processor(Processor.Arch.BIT_64, Processor.Type.IA_64);
		addProcessors(processor, "ia64", "ia64w");
	}

	private static void init_PPC_32Bit() {
		final Processor processor = new Processor(Processor.Arch.BIT_32, Processor.Type.PPC);
		addProcessors(processor, "ppc", "power", "powerpc", "power_pc", "power_rs");
	}

	private static void init_PPC_64Bit() {
		final Processor processor = new Processor(Processor.Arch.BIT_64, Processor.Type.PPC);
		addProcessors(processor, "ppc64", "power64", "powerpc64", "power_pc64", "power_rs64");
	}

	/**
	 * Adds the given {@link Processor} with the given key {@link String} to the
	 * map.
	 *
	 * @param key       The key as {@link String}.
	 * @param processor The {@link Processor} to add.
	 * @throws IllegalStateException If the key already exists.
	 */
	private static void addProcessor(final String key, final Processor processor) {
		if (ARCH_TO_PROCESSOR.containsKey(key)) {
			throw new IllegalStateException("Key " + key + " already exists in processor map");
		}
		ARCH_TO_PROCESSOR.put(key, processor);
	}

	/**
	 * Adds the given {@link Processor} with the given keys to the map.
	 *
	 * @param keys      The keys.
	 * @param processor The {@link Processor} to add.
	 * @throws IllegalStateException If the key already exists.
	 */
	private static void addProcessors(final Processor processor, final String... keys) {
		Stream.of(keys).forEach(e -> addProcessor(e, processor));
	}

	/**
	 * Returns a {@link Processor} object of the current JVM.
	 *
	 * <p>
	 * Important: The os.arch System Property returns the architecture used by the
	 * JVM not of the operating system.
	 * </p>
	 *
	 * @return A {@link Processor} when supported, else {@code null}.
	 */
	public static Processor getProcessor() {
		return getProcessor(SystemUtils.OS_ARCH);
	}

	/**
	 * Returns a {@link Processor} object the given value {@link String}. The
	 * {@link String} must be like a value returned by the os.arch System Property.
	 *
	 * @param value A {@link String} like a value returned by the os.arch System
	 *              Property.
	 * @return A {@link Processor} when it exists, else {@code null}.
	 */
	public static Processor getProcessor(final String value) {
		return ARCH_TO_PROCESSOR.get(value);
	}

}
