entaxy-public/platform/runtime/base/base-support/src/main/java/ru/entaxy/platform/base/support/osgi/OSGIUtils.java

/*-
 * ~~~~~~licensing~~~~~~
 * base-support
 * ==========
 * Copyright (C) 2020 - 2023 EmDev LLC
 * ==========
 * You may not use this file except in accordance with the License Terms of the Copyright
 * Holder located at: https://entaxy.ru/eula . All copyrights, all intellectual property
 * rights to the Software and any copies are the property of the Copyright Holder. Unless
 * it is explicitly allowed the Copyright Holder, the User is prohibited from using the
 * Software for commercial purposes to provide services to third parties.
 * 
 * The Copyright Holder hereby declares that the Software is provided on an "AS IS".
 * Under no circumstances does the Copyright Holder guarantee or promise that the
 * Software provided by him will be suitable or not suitable for the specific purposes
 * of the User, that the Software will meet all commercial and personal subjective
 * expectations of the User, that the Software will work properly, without technical
 * errors, quickly and uninterruptedly.
 * 
 * Under no circumstances shall the Copyright Holder or its Affiliates is not liable
 * to the User for any direct or indirect losses of the User, his expenses or actual
 * damage, including, downtime; loss of bussines; lost profit; lost earnings; loss
 * or damage to data, property, etc.
 * ~~~~~~/licensing~~~~~~
 */
package ru.entaxy.platform.base.support.osgi;

import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.FrameworkUtil;
import org.osgi.framework.ServiceReference;
import org.osgi.util.tracker.ServiceTracker;

import ru.entaxy.platform.base.support.CommonUtils;

public class OSGIUtils {

	protected static abstract class ServicesEntryPoint<T extends ServicesEntryPoint<T>> {
		
		protected Class<?> serviceClass = null;
		protected String serviceClassName = null;
		
		protected String filter = null;
		
		protected int wait = -1;
		
		protected BundleContext bundleContext = FrameworkUtil.getBundle(OSGIUtils.class).getBundleContext();
		
		public T ofClass(Class<?> clazz) {
			this.serviceClass = clazz;
			return this.getBuilder();
		}
		
		public T ofClass(String className) /* throws Exception */ {
			this.serviceClassName = className;
//			BundleWiring wiring = this.bundleContext.getBundle().adapt(BundleWiring.class);
//			ClassLoader cl = wiring.getClassLoader();
//			this.serviceClass = cl.loadClass(this.serviceClassName);
			return this.getBuilder();
		}
		
		public T bundleContext(BundleContext context) {
			if (context == null)
				this.bundleContext = FrameworkUtil.getBundle(OSGIUtils.class).getBundleContext();
			else
				this.bundleContext = context;
			return getBuilder();
		}
		
		protected abstract T getBuilder();
	} 
	
	public static class ServicesFindHelper extends ServicesEntryPoint<ServicesFindHelper> {
	
		@Override
		protected ServicesFindHelper getBuilder() {
			return this;
		}
	
		protected String getClassFilter() {
			String className = (this.serviceClass != null)
					?this.serviceClass.getName()
					:this.serviceClassName;
			return "(" + 
					(CommonUtils.isValid(className)
					?(Constants.OBJECTCLASS + "=" + className)
					:"")
					+ ")";
		}
		
		public ServicesFindHelper filter(String filter) {
			this.filter = filter;
			return this;
		}
		
		public ServicesFindHelper waitService(int millis) {
			this.wait = millis;
			return this;
		}
		
		public <T> T get() throws Exception {
			String classFilter = getClassFilter();
			String finalFilter = "";
			if (CommonUtils.isValid(classFilter))
				if (CommonUtils.isValid(this.filter))
					finalFilter = String.format("(&%s%s)", classFilter, this.filter);
				else
					finalFilter = "(" + classFilter + ")";
			else
				if (CommonUtils.isValid(this.filter))
					finalFilter = "(" + this.filter + ")";
				else
					finalFilter = "";
			if (wait > 0) {
				// wait for service
				ServiceTracker tracker;
				if (CommonUtils.isValid(this.filter))
					tracker = new ServiceTracker<>(this.bundleContext, this.bundleContext.createFilter(finalFilter), null);
				else
					tracker = new ServiceTracker<>(this.bundleContext, this.bundleContext.createFilter(classFilter), null);
				tracker.open();
				tracker.waitForService(this.wait);
		        ServiceReference<?> connectionManagerServiceReference =
		        		tracker.getServiceReference();
				tracker.close();
		        return (T)bundleContext.getService(connectionManagerServiceReference);				
			} else {
				ServiceReference<?>[] serviceReferences;
				ServiceReference<?> serviceReference;
				if (this.serviceClass != null)
					this.serviceClassName = this.serviceClass.getName();
				if (!CommonUtils.isValid(this.serviceClassName))
					return null;
				if (CommonUtils.isValid(this.filter)) {
					serviceReferences = this.bundleContext.getServiceReferences(serviceClassName, this.filter);
					serviceReference = serviceReferences.length>0
							?serviceReferences[0]
							:null;
				} else {
					serviceReference = this.bundleContext.getServiceReference(serviceClassName);
				}
				if (serviceReference == null)
					return null;
				return (T) this.bundleContext.getService(serviceReference);
			}
		}
		
	}
	
	public static class ServicesHelper extends ServicesEntryPoint<ServicesFindHelper> {
		private ServicesFindHelper findHelper = new ServicesFindHelper();
		
		@Override
		public ServicesFindHelper ofClass(Class<?> clazz) {
			return findHelper.ofClass(clazz);
		}
		
		@Override
		public ServicesFindHelper ofClass(String className) {
			return findHelper.ofClass(className);
		}
		
		@Override
		protected ServicesFindHelper getBuilder() {
			return findHelper;
		}
		
	}
	
	static public <T> T getService(Class<T> serviceClass) {
		BundleContext bundleContext = FrameworkUtil.getBundle(OSGIUtils.class).getBundleContext();
		return getService(bundleContext, serviceClass);
	}

	
	static public <T> T getService(BundleContext bundleContext, Class<T> serviceClass) {
		T result = null;
		ServiceReference<T> ref = bundleContext.getServiceReference(serviceClass);
		if (ref != null) {
			result = bundleContext.getService(ref);
		}
		return result;
	}

	static public ServicesHelper services() {
		return new ServicesHelper();
	}
	
}