/**
 *
 */
package org.gcube.datatransfer.resolver.caches;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

import org.gcube.common.scope.api.ScopeProvider;
import org.gcube.datatransfer.resolver.catalogue.resource.ApplicationProfileReaderForCatalogueResolver;
import org.gcube.datatransfer.resolver.listeners.UriResolverStartupListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.cache.RemovalListener;
import com.google.common.cache.RemovalNotification;


/**
 * The Class LoadingCatalogueApplicationProfilesCache.
 *
 * @author Francesco Mangiacrapa at ISTI-CNR (francesco.mangiacrapa@isti.cnr.it)
 * Nov 5, 2018
 */
public class LoadingCatalogueApplicationProfilesCache {

	private static Logger logger = LoggerFactory.getLogger(LoadingCatalogueApplicationProfilesCache.class);
	private static LoadingCache<String, String> catalogueApplicationProfiles;

	static{

		CacheLoader<String, String> loader = new CacheLoader<String, String>(){

			@Override
			public String load(String vreName)
				throws Exception {

				logger.info("Loading the cache for vreName: "+vreName);
				String fullScope = loadFullScopeByApplicationProfile(vreName);
				logger.info("Returning fullScope: "+fullScope+ " for the VRE name: "+vreName);
				return fullScope;
			}

		};

		RemovalListener<String, String> removalListener = new RemovalListener<String, String>() {

			@Override
			public void onRemoval(RemovalNotification<String, String> arg0) {

				logger.info(LoadingCatalogueApplicationProfilesCache.class.getSimpleName() +" cache expired");

			}
		};

		catalogueApplicationProfiles = CacheBuilder.newBuilder().maximumSize(100).expireAfterWrite(
			1, TimeUnit.HOURS).removalListener(removalListener).
			build(loader);

		try{
			//PRE-POPULATE CACHE
			logger.info("Trying to pre-poluate catalogue resolver cache");
		    ScopeProvider.instance.set(UriResolverStartupListener.getContextScope());
			ApplicationProfileReaderForCatalogueResolver appPrCatResolver = new ApplicationProfileReaderForCatalogueResolver(UriResolverStartupListener.getContextScope(), true);
			catalogueApplicationProfiles.asMap().putAll(appPrCatResolver.getHashVreNameScope());

			logger.info(LoadingCatalogueApplicationProfilesCache.class.getSimpleName() +" instancied");
			logger.info("Pre-Loaded CatalogueApplicationProfiles cache is: "+catalogueApplicationProfiles.asMap().toString());
		}catch(Exception e){

		}finally{

		}

	}

	/**
	 * Gets the cache.
	 *
	 * @return the cache
	 */
	public static LoadingCache<String, String> getCache(){
		return catalogueApplicationProfiles;
	}



	/**
	 * Load application profiles.
	 *
	 * @param vreName the vre name
	 * @return the string
	 */
	public static String loadFullScopeByApplicationProfile(String vreName){

		String fullScope = null;
		try {

			fullScope = catalogueApplicationProfiles.get(vreName);
		}
		catch (ExecutionException e) {
			logger.warn("ExecutionException: ",e);
		}

		if(fullScope==null){
			logger.debug("FullScope is null for VRE_NAME: "+vreName+" into Application Profile: "+ApplicationProfileReaderForCatalogueResolver.RESOURCE_NAME+", reading profile again");
			ApplicationProfileReaderForCatalogueResolver appPrCatResolver = new ApplicationProfileReaderForCatalogueResolver(UriResolverStartupListener.getContextScope(), true);
			catalogueApplicationProfiles.asMap().putAll(appPrCatResolver.getHashVreNameScope());
		}

		return fullScope;
	}

}