/**
 * Copyright 2013 the original author or authors.
 * 
 * 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.
**/

package io.neba.core.blueprint;

import org.eclipse.gemini.blueprint.context.event.OsgiBundleApplicationContextEvent;
import org.eclipse.gemini.blueprint.context.event.OsgiBundleApplicationContextListener;
import org.eclipse.gemini.blueprint.context.event.OsgiBundleContextFailedEvent;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleException;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;

import static io.neba.core.util.BundleUtil.displayNameOf;
import static org.osgi.framework.Bundle.ACTIVE;
import static org.osgi.framework.Bundle.STARTING;

/**
 * When an application context activation fails, NEBA removes any previously
 * registered resource models, self tests, MVC infrastructure and the like, since these
 * are registered before the application context is
 * {@link org.springframework.context.ConfigurableApplicationContext#refresh() activated}.
 *
 * @author Olaf Otto
 */
@Service("osgiApplicationContextListener")
public class ContextFailedHandler extends ContextShutdownHandler
                                  implements OsgiBundleApplicationContextListener<OsgiBundleApplicationContextEvent> {
    /**
     * This method is executed asynchronously since the original extender thread may try to obtain a lock to the OSGi
     * framework's registry state during the stop while holding the event handling lock, which may result in a transitive
     * deadlock.
     */
    @Override
    @Async
    public void onOsgiApplicationEvent(OsgiBundleApplicationContextEvent event) {
        // We need to use the generic OsgiBundleApplicationContextEvent here and test
        // for instanceof since gemini-blueprint does not correctly determine
        // the event type we are listening for.
        if (event instanceof OsgiBundleContextFailedEvent) {
            final Bundle bundle = event.getBundle();

            handleStop(bundle);
            stop(bundle);
        }
    }

    private void stop(Bundle bundle) {
        try {
            if (canStop(bundle)) {
                bundle.stop();
            }
        } catch (BundleException e) {
            throw new RuntimeException("Unable to stop bundle " + displayNameOf(bundle) + ".", e);
        }
    }

    private boolean canStop(Bundle bundle) {
        return bundle.getState() == ACTIVE || bundle.getState() ==  STARTING;
    }
}