package org.gcube.smartgears.managers;

import static org.gcube.smartgears.Constants.container_profile_file_path;
import static org.gcube.smartgears.lifecycle.container.ContainerState.active;
import static org.gcube.smartgears.lifecycle.container.ContainerState.down;
import static org.gcube.smartgears.lifecycle.container.ContainerState.failed;
import static org.gcube.smartgears.lifecycle.container.ContainerState.stopped;
import static org.gcube.smartgears.provider.ProviderFactory.provider;

import java.io.File;
import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.util.List;
import java.util.Set;

import org.gcube.common.events.Observes;
import org.gcube.common.events.Observes.Kind;
import org.gcube.smartgears.configuration.Mode;
import org.gcube.smartgears.context.application.ApplicationContext;
import org.gcube.smartgears.context.container.ContainerContext;
import org.gcube.smartgears.handlers.ProfileEvents;
import org.gcube.smartgears.handlers.container.ContainerHandler;
import org.gcube.smartgears.handlers.container.ContainerLifecycleEvent;
import org.gcube.smartgears.handlers.container.ContainerPipeline;
import org.gcube.smartgears.lifecycle.application.ApplicationLifecycle;
import org.gcube.smartgears.lifecycle.container.ContainerState;
import org.gcube.smartgears.utils.Utils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Coordinates management of the container as a gCube resource.
 * 
 * @author Fabio Simeoni
 * 
 */
public class ContainerManager {

	private static Logger log = LoggerFactory.getLogger(ContainerManager.class);

	public static ContainerManager instance = new ContainerManager();

	private ContainerContext context;

	private ContainerPipeline pipeline;

	private ContainerManager() {}

	/**
	 * Starts container management.
	 */
	public ContainerContext start(ContainerContext context) {

		this.context = context;

		try {
			

			if (context.configuration().mode()!=Mode.offline)
				validateContainer(context);

			saveContainerState();

			List<ContainerHandler> handlers = provider().containerHandlers();

			log.trace("managing container lifecycle with {}", handlers);

						
			startHandlers(handlers);

			context.lifecycle().moveTo(active);
			
			return context;
		}
		catch(RuntimeException e) {

			log.error("cannot manage container (see cause)",e);

			if (context!=null)
				context.lifecycle().moveTo(failed);

			throw e;
		}

	}


	private void saveContainerState() {
		File file = context.persistenceWriter().file(container_profile_file_path);		
		try(ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(file))){
			oos.writeObject(context.id());
		}catch (Exception e) {
			log.error("error serializing cointainer state");
			throw new RuntimeException(e);
		}

	}

	private void validateContainer(ContainerContext context) {
		//List<String> tokensToRemove = new ArrayList<String>();
		context.configuration().validate();
		Set<String> foundContexts;
						
		try {
			foundContexts = context.authorizationProvider().getContexts();
		} catch (Exception e) {
			log.error("error authorizing container",e);
			throw new RuntimeException("error authorizing container, moving the container to failed",e);
		}		

		if (foundContexts.isEmpty()){
			log.error("no valid contexts found, moving the container to failed");
			throw new RuntimeException("no valid contexts found, moving the container to failed");
		}
		
	}

	public void manage(ApplicationContext app) {
		app.events().subscribe(this); 
	}

	@Observes(value={ApplicationLifecycle.failure,ApplicationLifecycle.stop},kind=Kind.critical)
	void monitorApplication(ApplicationLifecycle lifecycle) {
		context.lifecycle().tryMoveTo(ContainerState.partActive);
	}

	@Observes(value=ContextEvents.ADD_CONTEXT_TO_CONTAINER,kind=Kind.critical)
	void addContext(String scope) {
		log.info("adding context {} event send", context);
		context.events().fire(scope, ProfileEvents.addToContext);
	}

	@Observes(value=ContextEvents.REMOVE_CONTEXT_FROM_CONTAINER,kind=Kind.critical)
	void removeContext(String scope) {
		log.info("removing context {} event send", context);
		context.events().fire(scope, ProfileEvents.removeFromContext);
	}

	/**
	 * Stops container management on remote request.
	 * 
	 */
	public void stop() {

		stop(false);
	}


	/**
	 * Stops container management on remote request or container shutdown.
	 * 
	 */
	public void stop(boolean shutdown) {

		//two cases: stop-on-shutdown and stop-on-request, some listeners will be selective about this,

		//shutdown is triggered by probe app, which is notified among other apps
		//if other app have been already notified, the container may already be part-active.
		//apps still to notify will listen only on stop, hence won't react to this but will go down when their turn arrives.

		if (context == null)
			return;

		log.info("stopping container management");

		try {

			context.lifecycle().tryMoveTo(shutdown?down:stopped);
			
			stopHandlers();

			//no further reactions
			log.info("stopping container events");
			context.events().stop();
			Utils.scheduledServicePool.shutdownNow();

		} 
		catch (RuntimeException e) {

			log.warn("cannot stop container management (see cause)", e);
		}

	}



	//helpers

	private void startHandlers(List<ContainerHandler> handlers) {

		try {

			pipeline = new ContainerPipeline(handlers);

			pipeline.forward(new ContainerLifecycleEvent.Start(context));

		} catch (RuntimeException e) {

			context.lifecycle().tryMoveTo(failed);
			throw e;
		}
	}


	private void stopHandlers() {

		if (pipeline == null)
			return;

		// copy pipeline, flip it, and
		ContainerPipeline returnPipeline = pipeline.reverse();

		// start lifetime pipeline in inverse order with stop event
		returnPipeline.forward(new ContainerLifecycleEvent.Stop(context));

	}
/*
	private void loadKeyForToken(List<String> tokens) {
		String initialToken = SecurityTokenProvider.instance.get();

		//TODO: change this
		String filePath = "/tmp/keys";
		File PathDirs = new File(filePath+"/");
		PathDirs.mkdirs();
		try{
			for (String token : tokens)	{
				try{
					SecurityTokenProvider.instance.set(token);
					File key = authProvider.getSymmKey(filePath);
					log.trace("loading key {} file name ",key.getAbsolutePath());
					log.trace("loaded key {} file name ",key.getAbsolutePath());
				}catch(Exception e){
					log.warn("error loading key for token {}", token, e);
				}
			}
			loadFileIntoClasspath(PathDirs);
		}finally{
			SecurityTokenProvider.instance.set(initialToken);
		}
	}
	
	
	private void loadFileIntoClasspath(File file){
		try {
		    URL url = file.toURI().toURL();
		    
		    ClassLoader currentClassloader = Thread.currentThread().getContextClassLoader().getParent()==null?
		    		Thread.currentThread().getContextClassLoader() : Thread.currentThread().getContextClassLoader().getParent();
		    
		    URLClassLoader classLoader = (URLClassLoader)currentClassloader;
		    Method method = URLClassLoader.class.getDeclaredMethod("addURL", URL.class);
		    method.setAccessible(true);
		    method.invoke(classLoader, url);
		} catch (Exception ex) {
		   	log.error("error loading file into classpath",ex);
		}
	}
	*/
}