SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// Multi-Phasic Applications: SquirrelJME
//     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
// ---------------------------------------------------------------------------
// SquirrelJME is under the Mozilla Public License Version 2.0.
// See license.mkd for licensing and copyright information.
// ---------------------------------------------------------------------------

package cc.squirreljme.emulator;

import cc.squirreljme.jvm.mle.RuntimeShelf;
import cc.squirreljme.jvm.mle.constants.VMDescriptionType;
import cc.squirreljme.jvm.mle.constants.VMStatisticType;
import cc.squirreljme.jvm.mle.exceptions.MLECallError;

/**
 * Emulated shelf for {@link RuntimeShelf}.
 *
 * @since 2021/08/08
 */
public class EmulatedRuntimeShelf
{
    /**
     * Same as {@link RuntimeShelf#systemEnv(String)}.
     * 
     * @param __key The environment variable key.
     * @return The value of the variable if it is set, otherwise {@code null}.
     * @throws MLECallError If key is {@code null}.
     * @since 2023/02/02
     */
    @SuppressWarnings("CallToSystemGetenv")
    public static String systemEnv(String __key)
        throws MLECallError
    {
        if (__key == null)
            throw new MLECallError("No key specified.");
        
        return System.getenv(__key);
    }
    
    /**
     * Same as {@link RuntimeShelf#vmDescription(int)}.
     *
     * @param __type One of {@link VMDescriptionType}.
     * @return The string for the given description or {@code null} if not
     * set.
     * @throws MLECallError If {@code __type} is not valid.
     * @since 2020/06/17
     */
    public static String vmDescription(int __type)
        throws MLECallError
    {
        switch (__type)
        {
            case VMDescriptionType.UNSPECIFIED:
                return null;
            
            case VMDescriptionType.VM_VERSION:
                return System.getProperty("java.vm.version");
            
            case VMDescriptionType.VM_NAME:
                return System.getProperty("java.vm.name");
            
            case VMDescriptionType.VM_VENDOR:
                return System.getProperty("java.vm.vendor");
            
            case VMDescriptionType.VM_EMAIL:
                return System.getProperty("java.vm.vendor.email");
            
            case VMDescriptionType.VM_URL:
                return System.getProperty("java.vm.vendor.url");
            
            case VMDescriptionType.EXECUTABLE_PATH:
                return null;
            
            case VMDescriptionType.OS_NAME:
                return System.getProperty("os.name");
            
            case VMDescriptionType.OS_VERSION:
                return System.getProperty("os.version");
            
            case VMDescriptionType.OS_ARCH:
                return System.getProperty("os.arch");
            
            case VMDescriptionType.VM_SECURITY_POLICY:
                return null;
                
            default:
                throw new MLECallError("Invalid " + __type);
        }
    }
    
    /**
     * Returns a statistic of the virtual machine.
     *
     * @param __type The {@link VMStatisticType}.
     * @return The value of the statistic, or {@code 0L} if not set.
     * @throws MLECallError If {@code __type} is not valid.
     * @since 2022/10/03
     */
    public static long vmStatistic(int __type)
        throws MLECallError
    {
        if (__type < 0 || __type >= VMStatisticType.NUM_STATISTICS)
            throw new MLECallError("Bad statistic: " + __type);
        
        switch (__type)
        {
            case VMStatisticType.CPU_THREAD_COUNT:
                return Runtime.getRuntime().availableProcessors();
            
            case VMStatisticType.MEM_FREE:
                return Runtime.getRuntime().freeMemory();
            
            case VMStatisticType.MEM_MAX:
                return Runtime.getRuntime().maxMemory();
            
            case VMStatisticType.MEM_USED:
                return Runtime.getRuntime().totalMemory();
        }
        
        return 0L;
    }
}