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A simple platform on which Java/Swing desktop applications may be built. This updated version has packaged the entire library into a single JAR file. We have also made the following changes: ToolBarGenerator should now create ButtonGroups properly for state actions. ApplicationContext has accessors for the WindowManager, DockingManager, StatusDisplayer, and ProgressHandler implementations. It defaults to testing the Application's MainView and the MainView's StatusBar, then uses the Lookup, if the MainView and its StatusBar do not implement the desired interfaces. StatusMessage now uses the com.pekinsoft.desktop.error.ErrorLevel instead of the java.util.logging.Level, so that the levels will no longer need to be cast in order to be used.

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/*
 * Copyright (C) 2023 PekinSOFT Systems
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 * 
 * *****************************************************************************
 *  Project    :   LookupAPI
 *  Class      :   ModuleHelper.java
 *  Author     :   Sean Carrick
 *  Created    :   Jan 17, 2023
 *  Modified   :   Jan 17, 2023
 *  
 *  Purpose: See class JavaDoc for explanation
 *  
 *  Revision History:
 *  
 *  WHEN          BY                   REASON
 *  ------------  -------------------  -----------------------------------------
 *  Jan 17, 2023  Sean Carrick         Initial creation.
 * *****************************************************************************
 */

package com.pekinsoft.lookup;

import java.lang.module.ModuleDescriptor;
import java.lang.module.ModuleFinder;
import java.lang.module.ModuleReference;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Set;

/**
 * `ModuleHelper` simply allows for us to remove *most* of the error handling out
 * of the `Lookup`s.
 *
 * @author Sean Carrick <sean at pekinsoft dot com>
 * 
 * @version 1.0
 * @since 1.0
 */
class ModuleHelper {
    
    private final ModuleFinder finder;
    private final ClassLoader loader;
    private final Class type;
    
    ModuleHelper (ModuleFinder finder, ClassLoader loader, Class type) {
        this.finder = finder;
        this.loader = loader;
        this.type = type;
    }
    
    Class find() {
        Class cls = null;
        
        final Set refs = finder.findAll();
        
        for (ModuleReference r : refs) {
            ModuleDescriptor d = r.descriptor();
            
            for (ModuleDescriptor.Provides p : d.provides()) {
                if (p.service().equals(type.getName())) {
                    String provider = p.providers().get(0); // The first one.
                    
                    try {
                        cls = loader.loadClass(provider);
                        break;
                    } catch (ClassNotFoundException cnfe) {
                        // TODO: Handle the exception.
                    }
                }
            }
            
            if (cls != null) {
                break;
            }
        }
        
        return cls;
    }
    
    boolean isSingleton(Class cls) {
        try {
            Method getInstance = cls.getMethod("getInstance");
            if (getInstance != null) {
                return true;
            }
        } catch (NoSuchMethodException 
                | SecurityException e) {
            return false;
        }
        
        return false;
    }
    
    boolean isProvider(Class cls) {
        try {
            Method provider = cls.getMethod("provider");
            if (provider != null) {
                return true;
            }
        } catch (NoSuchMethodException
                | SecurityException e) {
            return false;
        }
        
        return false;
    }
    
    Object getInstance(Class cls) {
        try {
            Method getInstance = cls.getMethod("getInstance");
            if (getInstance != null) {
                if (!getInstance.canAccess(null)) {
                    getInstance.setAccessible(true);
                }
                
                return getInstance.invoke(cls);
            }
        } catch (IllegalAccessException 
                | IllegalArgumentException 
                | NoSuchMethodException 
                | SecurityException 
                | InvocationTargetException e) {
            return null;
        }
        return null;
    }
    
    Object getProvider(Class cls) {
        try {
            Method provider = cls.getMethod("provider");
            if (provider != null) {
                if (!provider.canAccess(null)) {
                    provider.setAccessible(true);
                }
                
                return provider.invoke(cls);
            }
        } catch (IllegalAccessException 
                | IllegalArgumentException 
                | NoSuchMethodException 
                | SecurityException 
                | InvocationTargetException e) {
            return null;
        }
        return null;
    }

}