package org.gcube.smartgears.provider;

import static org.gcube.smartgears.Constants.configuration_file_path;
import static org.gcube.smartgears.Constants.container_configuraton_file_path;
import static org.gcube.smartgears.Constants.container_profile_file_path;
import static org.gcube.smartgears.Constants.default_extensions_file_path;
import static org.gcube.smartgears.Constants.extensions_file_path;
import static org.gcube.smartgears.Constants.ghn_home_env;
import static org.gcube.smartgears.Constants.ghn_home_property;
import static org.gcube.smartgears.Constants.library_configuration_file_path;
import static org.gcube.smartgears.Constants.profile_file_path;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Set;
import java.util.UUID;

import javax.servlet.ServletContext;

import org.gcube.common.events.Hub;
import org.gcube.common.events.impl.DefaultHub;
import org.gcube.smartgears.configuration.application.ApplicationConfiguration;
import org.gcube.smartgears.configuration.application.ApplicationConfigurationBinder;
import org.gcube.smartgears.configuration.application.ApplicationExtensions;
import org.gcube.smartgears.configuration.application.ApplicationHandlers;
import org.gcube.smartgears.configuration.application.BridgedApplicationConfiguration;
import org.gcube.smartgears.configuration.container.ContainerConfiguration;
import org.gcube.smartgears.configuration.container.ContainerConfigurationBinder;
import org.gcube.smartgears.configuration.library.SmartGearsConfiguration;
import org.gcube.smartgears.configuration.library.SmartGearsConfigurationBinder;
import org.gcube.smartgears.context.Properties;
import org.gcube.smartgears.context.application.ApplicationContext;
import org.gcube.smartgears.context.application.DefaultApplicationContext;
import org.gcube.smartgears.context.container.ContainerContext;
import org.gcube.smartgears.context.container.DefaultContainerContext;
import org.gcube.smartgears.handlers.container.ContainerHandler;
import org.gcube.smartgears.lifecycle.application.ApplicationLifecycle;
import org.gcube.smartgears.lifecycle.container.ContainerLifecycle;
import org.gcube.smartgears.publishing.Publisher;
import org.gcube.smartgears.publishing.SmartgearsProfilePublisher;
import org.gcube.smartgears.security.AuthorizationProvider;
import org.gcube.smartgears.utils.Utils;
import org.reflections.Reflections;
import org.reflections.scanners.SubTypesScanner;
import org.reflections.scanners.TypeAnnotationsScanner;
import org.reflections.util.ClasspathHelper;
import org.reflections.util.ConfigurationBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Default implementation of the {@link Provider} interface.
 * 
 * @author Fabio Simeoni
 *
 */
public class DefaultProvider implements Provider {

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

	private ContainerContext containerContext;
	//TODO: do the same with applicationContext (with a map)


	private File configFile = null;

	protected DefaultProvider(File configFile) {
		this.configFile = configFile;
	}

	List<Publisher> publishers;


	protected DefaultProvider(){};

	@Override
	public ContainerContext containerContext() {

		if(containerContext==null){
			ContainerConfiguration configuration = containerConfiguration();

			Hub hub = new DefaultHub();

			ContainerLifecycle lifecycle = new ContainerLifecycle(hub);

			File file = configuration.persistence().file(container_profile_file_path);

			String id = null;
			if (file.exists()){
				log.info("loading persisted state for container");
				try(ObjectInputStream ois = new ObjectInputStream(new FileInputStream(file))){
					id = (String)ois.readObject();
				}catch(Exception e){
					log.error("error loading persisted state, creating new uuid",e);
				}

			} 
			if (id==null){
				id = UUID.randomUUID().toString();
				log.info("container id created is {}",id);

			} 

			containerContext =  new DefaultContainerContext(id, configuration, hub, lifecycle, new Properties());
		}
		return containerContext;
	}

	@Override
	public List<ContainerHandler> containerHandlers() {

		try {

			ContainerConfigurationBinder binder = new ContainerConfigurationBinder();

			ClassLoader currentClassLoader = Thread.currentThread().getContextClassLoader();
			if (currentClassLoader.getParent()!=null && !currentClassLoader.getParent().equals(ClassLoader.getSystemClassLoader())){
				log.trace("probably i'm in a webapp classloader");
				currentClassLoader = currentClassLoader.getParent();
			}

			List<ContainerHandler> defaultHandlers =  binder.bindHandlers(currentClassLoader);

			return defaultHandlers;

		} catch (RuntimeException e) {

			throw new RuntimeException("cannot install container handlers (see cause) ", e);

		}
	}

	@Override
	public ApplicationContext contextFor(ContainerContext context, ServletContext application) {

		ApplicationConfiguration configuration = null;
		ApplicationConfiguration embedded = configurationFor(application);
		ApplicationConfiguration external = context.configuration().app(application.getContextPath());

		//shouldn't happen: management shouldn't have started at all
		if (embedded==null && external==null)			
			throw new AssertionError("application @ "+application.getContextPath()+" is not distributed with "
					+ configuration_file_path+" and there is no external configuration for it in "+container_configuraton_file_path);

		//no embedded configuration
		if (embedded == null) {

			configuration = external ;

			log.info("loaded  configuration for application "+configuration.name()+" from "+container_configuraton_file_path);
		}
		else  {

			configuration = embedded;

			if (external == null)

				log.info("loaded configuration for application "+configuration.name()+" from "+configuration_file_path);

			else {

				configuration.merge(external);

				log.info("loaded configuration for application "+configuration.name()+" from "+configuration_file_path+" and "+container_configuraton_file_path);

			}
		}	

		ApplicationConfiguration bridgedConfiguration = new BridgedApplicationConfiguration(context.configuration(),
				configuration);

		Hub hub = new DefaultHub();

		ApplicationLifecycle lifecycle = new ApplicationLifecycle(hub, configuration.name());

		File file = bridgedConfiguration.persistence().file(profile_file_path);
		String id= null;
		if (file.exists()){
			log.info("loading persisted state for application {}", application.getContextPath());
			try(ObjectInputStream ois = new ObjectInputStream(new FileInputStream(file))){
				id = (String)ois.readObject();
			}catch(Exception e){
				log.error("error loading persisted state, creating new uuid",e);
			}
		} 
		if (id==null)
			id = UUID.randomUUID().toString();

		return new DefaultApplicationContext(id, context, application, bridgedConfiguration, hub, lifecycle,
				new Properties());
	}

	@Override
	public ApplicationHandlers handlersFor(ApplicationContext context) {

		try {


			ApplicationConfigurationBinder binder = new ApplicationConfigurationBinder();



			//searching for smartegars related application handlers in the common classloader
			ClassLoader currentClassLoader = Thread.currentThread().getContextClassLoader();
			if (currentClassLoader.getParent()!=null && !currentClassLoader.getParent().equals(ClassLoader.getSystemClassLoader())){
				log.trace("probably i'm in a webapp classloader");
				currentClassLoader = currentClassLoader.getParent();
			}

			ApplicationHandlers defaultHandlers = binder.bindHandlers(currentClassLoader);

			return defaultHandlers;	


		} catch (RuntimeException e) {

			throw new RuntimeException("cannot install handlers for application @ " + context.name()+" (see cause) ", e);

		}
	}


	@Override
	public ApplicationExtensions extensionsFor(ApplicationContext context) {

		try {

			InputStream config = context.application().getResourceAsStream(extensions_file_path);

			if (config == null) {

				log.trace("{} uses default extensions as it does not include {}", context.name(), extensions_file_path);

				// it's in a library, using
				config = getClass().getResourceAsStream(default_extensions_file_path);

				if (config == null)
					throw new IllegalStateException("invalid distribution: cannot find " + default_extensions_file_path);

			} else
				log.info("{} uses custom extensions @ {}", context.name(), extensions_file_path);

			ApplicationConfigurationBinder binder = new ApplicationConfigurationBinder();

			return binder.bindExtensions(config);

		} catch (RuntimeException e) {

			throw new RuntimeException("cannot install extensions for application @ " + context.name()+" (see cause) ", e);

		}
	}


	@Override
	public SmartGearsConfiguration smartgearsConfiguration() {

		try {

			InputStream config = getClass().getResourceAsStream(library_configuration_file_path);

			if (config == null)
				throw new IllegalStateException("invalid distribution: cannot find " + library_configuration_file_path);

			SmartGearsConfigurationBinder binder = new SmartGearsConfigurationBinder();

			SmartGearsConfiguration configuration = binder.bind(config);

			configuration.validate();

			return configuration;
		} catch (RuntimeException e) {

			throw new RuntimeException("cannot read library configuration (see cause) ", e);

		}

	}

	// helpers
	private ApplicationConfiguration configurationFor(ServletContext application) {

		try {

			InputStream config = application.getResourceAsStream(configuration_file_path);

			if (config == null) 
				return null;

			ApplicationConfigurationBinder binder = new ApplicationConfigurationBinder();

			return binder.bind(config);

		} catch (RuntimeException e) {

			throw new RuntimeException("invalid configuration (see cause)", e);

		}
	}

	private ContainerConfiguration containerConfiguration() {

		if (configFile==null) {

			String home = Utils.home();

			if (home == null)
				throw new IllegalStateException("invalid node configuration: the environment variable " + ghn_home_env
						+ " or the system property " + ghn_home_property + " must be defined");

			File homeDir = new File(home);

			if (!(homeDir.exists() && homeDir.isDirectory() && homeDir.canRead() && homeDir.canWrite()))
				throw new IllegalStateException("invalid node configuration: home "+home+" does not exist or is not a directory or cannot be accessed in read/write mode");

			configFile = new File(homeDir,container_configuraton_file_path);


			log.trace("reading container configuration @ {} ", configFile.getAbsolutePath());
		}

		if (!(configFile.exists() && configFile.canRead()))
			throw new IllegalStateException("invalid node configuration: file "+configFile.getAbsolutePath()+" does not exist or cannot be accessed");

		ContainerConfiguration configuration;
		try (InputStream stream = new FileInputStream(configFile)){
			configuration=  new ContainerConfigurationBinder().load(stream);
		}catch (Exception e) {
			throw new IllegalStateException("invalid node configuration: file "+configFile.getAbsolutePath()+" is invalid", e);
		}

		return configuration;
	}

	@Override
	public synchronized List<Publisher> publishers() {
		if (this.publishers == null) {
			//retrieve from root class loader
			Collection<URL> urls =  ClasspathHelper.forClassLoader(Thread.currentThread().getContextClassLoader());
			urls.removeIf(url ->  url.toString().endsWith(".so") || url.toString().endsWith(".zip")  );


			ConfigurationBuilder reflectionConf =  new ConfigurationBuilder().addUrls(urls).setScanners(new TypeAnnotationsScanner(), new SubTypesScanner());

			Reflections reflection = new Reflections(reflectionConf); 

			Set<Class<?>> annotatedPublishers = reflection.getTypesAnnotatedWith(SmartgearsProfilePublisher.class);
			List<Publisher> foundPublishers = new ArrayList<Publisher>();
			for (Class<?> annotatedPublisher: annotatedPublishers) {
				if (Publisher.class.isAssignableFrom(annotatedPublisher))
					try {
						foundPublishers.add((Publisher)annotatedPublisher.newInstance());
						log.info("added class {} to publishers",annotatedPublisher);
					} catch (Exception e) {
						log.error("publisher class {} cannot be instantiated", annotatedPublisher.getCanonicalName(),e);
					} 
				else 
					log.warn("publisher class {} discarded, it doesn't implements Publisher class", annotatedPublisher.getCanonicalName());
				
			}
			this.publishers = foundPublishers;

			if (foundPublishers.isEmpty())
				log.warn("no publishers found in classloader");
		}
		
		return this.publishers;
	}


	@Override
	public AuthorizationProvider authorizationProvider() {
		return containerContext.configuration().authorizationProvider();
	}

}