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.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.UUID;
import java.util.stream.Collectors;

import javax.servlet.ServletContext;

import org.gcube.common.events.Hub;
import org.gcube.common.events.impl.DefaultHub;
import org.gcube.common.security.credentials.Credentials;
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.security.AuthorizationProviderFactory;
import org.gcube.smartgears.utils.Utils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import io.github.classgraph.ClassGraph;
import io.github.classgraph.ClassInfo;
import io.github.classgraph.ClassInfoList;
import io.github.classgraph.ScanResult;

/**
 * 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);

			}

			AuthorizationProviderFactory<?> authfactory = configuration.getauthorizationConfiguration()
					.getAuthProviderFactory();
			Credentials credentials = configuration.getauthorizationConfiguration().getCredentials();

			AuthorizationProvider authProvider = authfactory.connect(credentials);

			containerContext = new DefaultContainerContext(id, configuration, hub, lifecycle, authProvider,
					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) {

			Set<Class<?>> annotatedPublishers;

			try (ScanResult result = new ClassGraph().enableClassInfo().enableAnnotationInfo()
					.addClassLoader(Thread.currentThread().getContextClassLoader()).scan()) {

				ClassInfoList classInfos = result.getClassesWithAnnotation(SmartgearsProfilePublisher.class.getName());

				annotatedPublishers = classInfos.stream().map(ClassInfo::loadClass)
						.filter(c -> Publisher.class.isAssignableFrom(c)).collect(Collectors.toSet());

			}
			/*
			 * 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);
			 * 
			 * = reflection.getTypesAnnotatedWith(SmartgearsProfilePublisher.class);
			 */

			List<Publisher> foundPublishers = new ArrayList<Publisher>();
			for (Class<?> annotatedPublisher : annotatedPublishers) {
				try {
					foundPublishers.add((Publisher) annotatedPublisher.getDeclaredConstructor().newInstance());
					log.info("added class {} to publishers", annotatedPublisher);
				} catch (Throwable e) {
					log.error("publisher class {} cannot be instantiated", annotatedPublisher.getCanonicalName(), e);
				}

			}
			this.publishers = foundPublishers;

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

		return this.publishers;
	}

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

}