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.runtime.cldc.full;

import cc.squirreljme.jvm.mle.RuntimeShelf;
import cc.squirreljme.runtime.cldc.debug.Debugging;
import java.nio.file.Path;
import java.nio.file.Paths;

/**
 * Overriding path provider, to allow different paths to be used rather
 * than the system implied paths.
 *
 * @since 2024/03/15
 */
public class OverridingPathProvider
    extends SystemPathProvider
{
    /** The provider to wrap. */
    protected final SystemPathProvider provider;
    
    /**
     * Initializes the provider.
     *
     * @param __provider The provider to wrap around.
     * @throws NullPointerException On null arguments.
     * @since 2024/03/15
     */
    public OverridingPathProvider(SystemPathProvider __provider)
        throws NullPointerException
    {
        if (__provider == null)
            throw new NullPointerException("NARG");
        
        this.provider = __provider;
    }
    
    /**
     * {@inheritDoc}
     * @since 2024/03/15
     */
    @Override
    public Path cache()
    {
        Path replace = OverridingPathProvider.__env(
            "SQUIRRELJME_CACHE_HOME");
        if (replace != null)
            return replace;
        
        return this.provider.cache();
    }
    
    /**
     * {@inheritDoc}
     * @since 2024/03/15
     */
    @Override
    public Path config()
    {
        Path replace = OverridingPathProvider.__env(
            "SQUIRRELJME_CONFIG_HOME");
        if (replace != null)
            return replace;
        
        return this.provider.config();
    }
    
    /**
     * {@inheritDoc}
     * @since 2024/03/15
     */
    @Override
    public Path data()
    {
        Path replace = OverridingPathProvider.__env(
            "SQUIRRELJME_DATA_HOME");
        if (replace != null)
            return replace;
        
        return this.provider.data();
    }
    
    /**
     * {@inheritDoc}
     * @since 2024/03/15
     */
    @Override
    public Path state()
    {
        throw Debugging.todo();
    }
    
    /**
     * Obtains the variable with some transmutation as needed.
     *
     * @param __var The variable to get.
     * @return The resultant variable.
     * @throws NullPointerException On null arguments.
     * @since 2024/03/15
     */
    private static Path __env(String __var)
        throws NullPointerException
    {
        if (__var == null)
            throw new NullPointerException("NARG");
        
        // Get from the system environment, ignore if missing
        String val = RuntimeShelf.systemEnv(__var);
        if (val == null)
            return null;
        
        // Resolve path
        Path result = Paths.get(val);
        
        // Aliased home directory?
        if ((result.getRoot() == null || !result.isAbsolute()) &&
            result.getNameCount() >= 1 &&
            "~".equals(result.getName(0).toString()))
        {
            // Which OS are we on?
            String osName = System.getProperty("os.name").toLowerCase();
            
            // Need to find the home directory
            String homeVal;
            if (osName.contains("windows") || osName.contains("reactos"))
                homeVal = RuntimeShelf.systemEnv("USERPROFILE");
            else
                homeVal = RuntimeShelf.systemEnv("HOME");
            
            // Not valid? Just assume the given path is valid
            if (homeVal == null)
                return result;
            
            // Resolve the final path
            Path home = Paths.get(homeVal);
            return home.resolve(result.subpath(1, result.getNameCount()));
        }
        
        // Use the given path
        return result;
    }
}