SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// 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.vm;

import cc.squirreljme.vm.ResourceBasedClassLibrary;
import cc.squirreljme.vm.VMClassLibrary;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * This is a suite manager which is based on resources for accessing various
 * classes and other resources.
 *
 * @since 2018/11/14
 */
public final class ResourceBasedSuiteManager
    implements VMSuiteManager
{
    /** The class to get resources from. */
    protected final Class<?> actingclass;
    
    /** The prefix for libraries. */
    protected final String prefix;
    
    /** Cache of libraries. */
    private final Map<String, VMClassLibrary> _cache =
        new HashMap<>();
    
    /** Cache of all available suites. */
    private String[] _libs;
    
    /**
     * Initializes the suite manager.
     *
     * @param __act The class to source resources from.
     * @param __prefix The prefix for library lookup.
     * @throws NullPointerException On null arguments.
     * @since 2018/11/14
     */
    public ResourceBasedSuiteManager(Class<?> __act, String __prefix)
        throws NullPointerException
    {
        if (__act == null || __prefix == null)
            throw new NullPointerException("NARG");
        
        this.actingclass = __act;
        this.prefix = __prefix;
    }
    
    /**
     * {@inheritDoc}
     * @since 2023/12/18
     */
    @Override
    public int libraryId(VMClassLibrary __lib)
        throws IllegalArgumentException, NullPointerException
    {
        if (__lib == null)
            throw new NullPointerException("NARG");
        
        Map<String, VMClassLibrary> cache = this._cache;
        synchronized (cache)
        {
            // The library must have been previously loaded first
            if (!cache.values().contains(__lib))
                throw new IllegalArgumentException(
                    "Unknown library: " + __lib);
            
            Path path = __lib.path();
            return (path != null ? path.hashCode() : __lib.name().hashCode());
        }
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/11/14
     */
    @Override
    public final String[] listLibraryNames()
    {
        // Resources are fixed, so if this was done already use the cached
        // form instead
        String[] libs = this._libs;
        if (libs != null)
            return libs.clone();
        
        // There should be a suite list
        try (InputStream in = this.actingclass.getResourceAsStream(
            this.prefix + "suites.list"))
        {
            // Does not exist, so there is no known library list
            if (in == null)
            {
                this._libs = (libs = new String[0]);
                return libs;
            }
            
            // Will just be a normal list
            List<String> rv = new ArrayList<>();
            try (BufferedReader br = new BufferedReader(
                new InputStreamReader(in, "utf-8")))
            {
                for (;;)
                {
                    String ln = br.readLine();
                    
                    // EOF
                    if (ln == null)
                        break;
                    
                    // Trim and ignore empty lines
                    ln = ln.trim();
                    if (ln.isEmpty())
                        continue;
                    
                    // Add otherwise
                    rv.add(ln);
                }
            }
            
            // Cache and return
            this._libs = (libs = rv.<String>toArray(new String[rv.size()]));
            return libs;
        }
        
        /* {@squirreljme.error AK01 Could not read the library list.} */
        catch (IOException e)
        {
            throw new RuntimeException("AK01", e);
        }
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/11/14
     */
    @Override
    public final VMClassLibrary loadLibrary(String __s)
        throws NullPointerException
    {
        if (__s == null)
            throw new NullPointerException("NARG");
        
        Map<String, VMClassLibrary> cache = this._cache;
        synchronized (cache)
        {
            // Already got?
            VMClassLibrary rv = cache.get(__s);
            if (rv != null)
                return rv;
            
            // Pre-cached to not exist
            if (cache.containsKey(__s))
                return null;
            
            // Make sure it is actually valid
            boolean found = false;
            for (String q : this.listLibraryNames())
                if ((found |= q.equals(__s)))
                    break;
            
            // If it was not found, it does not exist so cache it and fail
            if (!found)
            {
                cache.put(__s, null);
                return null;
            }
            
            // Load and store it
            cache.put(__s,
                (rv = new ResourceBasedClassLibrary(this.actingclass,
                    this.prefix + __s + '/', __s)));
            
            return rv;
        }
    }
}