/**
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 */
package org.thingml.xtext.tests;

import com.google.inject.Guice;
import com.google.inject.Injector;
import org.eclipse.xtext.junit4.GlobalRegistries;
import org.eclipse.xtext.junit4.GlobalRegistries.GlobalStateMemento;
import org.eclipse.xtext.junit4.IInjectorProvider;
import org.eclipse.xtext.junit4.IRegistryConfigurator;
import org.thingml.xtext.ThingMLRuntimeModule;
import org.thingml.xtext.ThingMLStandaloneSetup;

public class ThingMLInjectorProvider implements IInjectorProvider, IRegistryConfigurator {

	protected GlobalStateMemento stateBeforeInjectorCreation;
	protected GlobalStateMemento stateAfterInjectorCreation;
	protected Injector injector;

	static {
		GlobalRegistries.initializeDefaults();
	}

	@Override
	public Injector getInjector() {
		if (injector == null) {
			stateBeforeInjectorCreation = GlobalRegistries.makeCopyOfGlobalState();
			this.injector = internalCreateInjector();
			stateAfterInjectorCreation = GlobalRegistries.makeCopyOfGlobalState();
		}
		return injector;
	}

	protected Injector internalCreateInjector() {
		return new ThingMLStandaloneSetup() {
			@Override
			public Injector createInjector() {
				return Guice.createInjector(createRuntimeModule());
			}
		}.createInjectorAndDoEMFRegistration();
	}

	protected ThingMLRuntimeModule createRuntimeModule() {
		// make it work also with Maven/Tycho and OSGI
		// see https://bugs.eclipse.org/bugs/show_bug.cgi?id=493672
		return new ThingMLRuntimeModule() {
			@Override
			public ClassLoader bindClassLoaderToInstance() {
				return ThingMLInjectorProvider.class
						.getClassLoader();
			}
		};
	}

	@Override
	public void restoreRegistry() {
		stateBeforeInjectorCreation.restoreGlobalState();
	}

	@Override
	public void setupRegistry() {
		getInjector();
		stateAfterInjectorCreation.restoreGlobalState();
	}
}