uri-resolver/src/main/java/org/gcube/datatransfer/resolver/caches/GeoExplorerApplicationURLGuavaCache.java

/**
 *
 */

package org.gcube.datatransfer.resolver.caches;

import java.util.concurrent.TimeUnit;

import org.gcube.datatransfer.resolver.applicationprofile.ApplicationProfileReader;
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 GeoExplorerApplicationHostnameGuavaCache.
 *
 * @author Francesco Mangiacrapa at ISTI-CNR (francesco.mangiacrapa@isti.cnr.it)
 * Nov 2, 2018
 */
public class GeoExplorerApplicationURLGuavaCache {

	private static Logger logger = LoggerFactory.getLogger(GeoExplorerApplicationURLGuavaCache.class);

	//A cache (Scope, GeoExplorer-URL)
	private static LoadingCache<String, String> geoExplorerApplicationURLCache;

	static {

		CacheLoader<String, String> loader = new CacheLoader<String, String> () {
			@Override
			public String load(String scope)
				throws Exception {
				logger.info(GeoExplorerApplicationURLGuavaCache.class.getSimpleName() +" loaded");
				return loadGeoExplorerApplicationURL(scope);
			}
		};

		RemovalListener<String, String> removalListener = new RemovalListener<String, String>() {
			  public void onRemoval(RemovalNotification<String, String> removal) {
				  logger.info(GeoExplorerApplicationURLGuavaCache.class.getSimpleName() +" cache expired");
			  }
		};

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

		logger.info(GeoExplorerApplicationURLGuavaCache.class.getSimpleName() +" instancied");
	}

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

		return geoExplorerApplicationURLCache;
	}



	/**
	 * Load geo explorer application url.
	 *
	 * @param scope the scope
	 * @return the string
	 */
	public static String loadGeoExplorerApplicationURL(String scope){

		if (scope == null || scope.isEmpty())
			logger.warn("Scope is null or ermpty, skipping loadGisViewerApplicationURL");

		ApplicationProfileReader reader = new ApplicationProfileReader(scope, UriResolverStartupListener.getGeoExplorerProfile().getGenericResource(), UriResolverStartupListener.getGeoExplorerProfile().getAppId(), false);
		String url = reader.getApplicationProfile().getUrl();
		logger.info("With scope "+scope+" loaded the GeoExplorer Application URL "+url);
		return url;

	}
}