package org.gcube.datatransfer.resolver.services;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.annotation.Nullable;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.ResponseBuilder;
import javax.ws.rs.core.StreamingOutput;

import org.apache.commons.io.IOUtils;
import org.gcube.common.scope.api.ScopeProvider;
import org.gcube.datatransfer.resolver.SingleFileStreamingOutput;
import org.gcube.datatransfer.resolver.gis.GeonetworkAccessParameter;
import org.gcube.datatransfer.resolver.gis.GeonetworkInstance;
import org.gcube.datatransfer.resolver.gis.GeonetworkServiceInterface;
import org.gcube.datatransfer.resolver.gis.exception.GeonetworkInstanceException;
import org.gcube.datatransfer.resolver.gis.geonetwork.FilterGetRecords;
import org.gcube.datatransfer.resolver.gis.geonetwork.GNAuthentication;
import org.gcube.datatransfer.resolver.gis.geonetwork.GeonetworkRequestFilterParameters.MODE;
import org.gcube.datatransfer.resolver.gis.geonetwork.GeonetworkRequestFilterParameters.VISIBILITY;
import org.gcube.datatransfer.resolver.gis.geonetwork.ReusableInputStream;
import org.gcube.datatransfer.resolver.services.error.ExceptionManager;
import org.gcube.datatransfer.resolver.services.exceptions.InternalServerException;
import org.gcube.datatransfer.resolver.util.GetResponseRecordFilter;
import org.gcube.datatransfer.resolver.util.HTTPCallsUtils;
import org.gcube.datatransfer.resolver.util.HTTPCallsUtils.HttpResponse;
import org.gcube.datatransfer.resolver.util.ScopeUtil;
import org.gcube.spatial.data.geonetwork.configuration.Configuration;
import org.gcube.spatial.data.geonetwork.model.Account;
import org.gcube.spatial.data.geonetwork.model.Account.Type;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;

/**
 * The Class GeonetworkResolver.
 *
 * @author Francesco Mangiacrapa at ISTI-CNR (francesco.mangiacrapa@isti.cnr.it)
 * Oct 23, 2018
 */
@Path("geonetwork")
public class GeonetworkResolver {

	/**
	 *
	 */
	public static final String REPLACED_A_PUBLIC_UUID_PLEASE_IGNORE = "Replaced a public UUID, please ignore";
	public static final String REPLACED_UUID_BY_FILTER_PLEASE_IGNORE = "Replaced UUID by "+GeonetworkResolver.class.getSimpleName()+" filters, please ignore";

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

	public static final String PATH_PARAM_MODE = "mode";
	public static final String PATH_PARAM_REQUEST_DELIMITER = "requestDelimiter";
//	public static final String PATH_PARAM_OWNER = "owner";
	private static final String PATH_PARAM_VISIBILITY = "visibility";

	private static final String PATH_PARAM_SCOPE = "scope";
	public static final String CSW_SERVER = "srv/en/csw";

	public static final String VALUE_OF_REQUEST_DELIMITIER = "$$";
	public static final String PATH_PARAM_REMAINPATH = "remainPath";

	public static final String QUERY_PARAM_RESET_CACHE_PARAM = "resetcache";
	public static final String QUERY_PARAM_RESET_CACHED_SCOPE_PARAM = "resetcachedscope";

	public static final String SRV_EN_MEF_EXPORT = "/srv/en/mef.export"; //MEF Geonetwork service

	public static final String UUID = "uuid";

	public static final String SCOPE_SEPARATOR = "|";

	protected Map<String, GeonetworkInstance> cacheGNInstances;

	private String help = "https://wiki.gcube-system.org/gcube/GCube_Resource_Catalogue#Geonetwork_Resolver";

	/**
	 * Gets the geonetwork request criteria.
	 * Creates a request criteria from input parameter pathWithoutGN
	 * The parameter pathWithoutGN should be an ordered string (like REST request):
	 * SCOPE/MODE/VISIBILITY/OWNER/$$
	 * SCOPE must be: ROOT|VO|VRE
	 * MODE must be: {@link MODE}
	 * VISIBILITY must be: {@link VISIBILITY}
	 * OWNER (is optional): filter by owner
	 *
	 * @param req the req
	 * @param mode the mode
	 * @param scope the scope
	 * @param visibility the visibility
	 * @param owner the owner - pass 'null' as string if no filter applied
	 * @param requestDelimiter the request delimiter
	 * @param resetCache the reset cache
	 * @param resetScope the reset scope
	 * @return the geonetwork request criteria
	 */

	@GET
	@Path("{"+PATH_PARAM_SCOPE+"}/{"+PATH_PARAM_MODE+"}/{"+PATH_PARAM_VISIBILITY+"}/{filterKey}/{filterValue}/$${"+PATH_PARAM_REMAINPATH+":(/[^?$]+)?}")
	public Response submitGet(@Context HttpServletRequest req,
		@PathParam(PATH_PARAM_SCOPE) @Nullable String scope,
		@PathParam(PATH_PARAM_MODE) @Nullable String mode,
		@PathParam(PATH_PARAM_VISIBILITY) @Nullable String visibility,
		@PathParam("filterKey") @Nullable String filterKey,
		@PathParam("filterValue") @Nullable String filterValue,
		@PathParam(PATH_PARAM_REMAINPATH) @Nullable String remainPath,
		@QueryParam(QUERY_PARAM_RESET_CACHE_PARAM) @Nullable String resetCache,
		@QueryParam(QUERY_PARAM_RESET_CACHED_SCOPE_PARAM) @Nullable String resetScope) {

		logger.info(this.getClass().getSimpleName()+" GET starts...");
		logger.info("Params are [mode: "+mode+", scope: "+scope+", visibility: "+visibility+", filterKey: "+filterKey+", filterValue: "+filterValue+", remainPath: "+remainPath+"]");

		if(scope==null || scope.isEmpty()){
			logger.error("Path Parameter 'scope' not found");
			ExceptionManager.throwBadRequestException(req, "Missing mandatory path parameter 'scope'", GeonetworkResolver.class, help);
		}

		if(mode==null || mode.isEmpty()){
			logger.error("Path Parameter 'scope' not found");
			ExceptionManager.throwBadRequestException(req, "Missing mandatory path parameter 'mode'", GeonetworkResolver.class, help);
		}

		scope = ScopeUtil.normalizeScope(scope, "|");
		mode = mode.toUpperCase();
		try{
			MODE.valueOf(mode);
		}catch(Exception e){
			List<MODE> toPrint = Arrays.asList(MODE.values());
			logger.error("The 'mode' parameter is wrong, Have you pass a valid parameter MODE like "+toPrint+"?");
			ExceptionManager.throwWrongParameterException(req, "The 'mode' parameter must be value of "+toPrint, GeonetworkResolver.class, help);
		}

		if(visibility==null){
			logger.error("Path Parameter 'visibility' not found");
			ExceptionManager.throwBadRequestException(req, "Missing mandatory path parameter 'visibility'", GeonetworkResolver.class, help);
		}

		visibility = visibility.toUpperCase();
		try{
			VISIBILITY.valueOf(visibility);
		}catch (Exception e) {
			List<VISIBILITY> toPrint = Arrays.asList(VISIBILITY.values());
			logger.error("The 'visibility' parameter is wrong, Have you pass a valid parameter VISIBILITY like "+toPrint+"?");
			ExceptionManager.throwWrongParameterException(req, "The 'visibility' parameter must be value of "+toPrint, GeonetworkResolver.class, help);
		}

		if(resetCache!=null && Boolean.parseBoolean(resetCache)){
			purgeCacheGeonetworkInstances();
		}

		if(resetScope!=null && Boolean.parseBoolean(resetScope)){
			resetGeonetoworkInstanceCacheForScope(scope);
		}

		logger.info("Remaining path is: "+remainPath);
		String gnGetlURL = null;
		try {

			GeonetworkInstance gnInstance = getGeonetworkInstanceForScope(scope);

			ScopeProvider.instance.set(scope);

			HTTPCallsUtils httpUtils = new HTTPCallsUtils();
			Configuration config = gnInstance.getGeonetworkPublisher().getConfiguration();
			String geonetworkUrl = config.getGeoNetworkEndpoint();
			String baseURL = remainPath==null ||remainPath.isEmpty()?geonetworkUrl+"/"+CSW_SERVER:geonetworkUrl+"/"+CSW_SERVER+remainPath;
			logger.info("The base URL is: "+baseURL);
			String queryString = req.getQueryString()==null || req.getQueryString().isEmpty()?"":"?"+req.getQueryString();
			gnGetlURL = baseURL+queryString;
			logger.info("Sending get request to URL: "+gnGetlURL);
			HttpResponse proxedGNResponse = httpUtils.get(gnGetlURL);

			switch(proxedGNResponse.getStatus()){
			case HttpServletResponse.SC_OK:

				//Building the response
				InputStream streamToWrite = IOUtils.toInputStream(proxedGNResponse.getResponse());
				StreamingOutput so = new SingleFileStreamingOutput(streamToWrite);

				logger.info("Response return Content-Type: "+httpUtils.getLastContentType());

				ResponseBuilder responseBuilder = Response
				.ok(so)
				//.header(ConstantsResolver.CONTENT_DISPOSITION,"attachment; filename = \""+fileName+"\"")
				.header(ConstantsResolver.CONTENT_TYPE, httpUtils.getLastContentType());
				return responseBuilder.build();

			case HttpServletResponse.SC_FORBIDDEN:
				ExceptionManager.throwForbiddenException(req, "You are not authorized to perform the request "+gnGetlURL, GeonetworkResolver.class, help);
				break;

			default:
				ExceptionManager.throwInternalErrorException(req, "Sorry, an error occurred performing the geonetwork request "+gnGetlURL+" with scope "+scope, GeonetworkResolver.class, help);
			}

		} catch (Exception e) {
			logger.error("Exception:", e);
			String error = "Sorry, an error occurred on resolving geonetwork request with scope "+scope+". Please, contact support!";
			ExceptionManager.throwInternalErrorException(req, error, GeonetworkResolver.class, help);
		}

		//An error occurred
		try {

			throw new InternalServerException(req, javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR, "Error during perform GET operation to: "+gnGetlURL, GeonetworkResolver.class, new URI(help));
		}
		catch (URISyntaxException e) {
			//silent
			return null;
		}

	}

//	/* (non-Javadoc)
//	 * @see javax.servlet.GenericServlet#init()
//	 */
//	@Override
//	public void init() throws ServletException {
//		super.init();
//		timer = new Timer(true);
//		timer.schedule(new TimerTask() {
//			@Override
//			public void run() {
//				logger.info("Resetting Geonetwork configuratiors cache...");
//				purgeCacheGeonetworkInstances();
//			}
//		}, CACHE_RESET_DELAY, CACHE_RESET_TIME);
//	}

	@POST
	@Path("{"+PATH_PARAM_SCOPE+"}/{"+PATH_PARAM_MODE+"}/{"+PATH_PARAM_VISIBILITY+"}/{filterKey}/{filterValue}/$${"+PATH_PARAM_REMAINPATH+":(/[^?$]+)?}")
	public Response submitPost(@Context HttpServletRequest req,
		@PathParam(PATH_PARAM_SCOPE) @Nullable String scope,
		@PathParam(PATH_PARAM_MODE) @Nullable String mode,
		@PathParam(PATH_PARAM_VISIBILITY) @Nullable String visibility,
		@PathParam("filterKey") @Nullable String filterKey,
		@PathParam("filterValue") @Nullable String filterValue,
		@PathParam(PATH_PARAM_REMAINPATH) @Nullable String remainPath,
		@QueryParam(QUERY_PARAM_RESET_CACHE_PARAM) @Nullable String resetCache,
		@QueryParam(QUERY_PARAM_RESET_CACHED_SCOPE_PARAM) @Nullable String resetScope) {

		logger.info(this.getClass().getSimpleName()+" POST starts...");

		if(scope==null || scope.isEmpty()){
			logger.error("Path Parameter 'scope' not found");
			ExceptionManager.throwBadRequestException(req, "Missing mandatory path parameter 'scope'", GeonetworkResolver.class, help);
		}

		if(mode==null || mode.isEmpty()){
			logger.error("Path Parameter 'scope' not found");
			ExceptionManager.throwBadRequestException(req, "Missing mandatory path parameter 'mode'", GeonetworkResolver.class, help);
		}

		scope = ScopeUtil.normalizeScope(scope, "|");
		mode = mode.toUpperCase();
		try{
			MODE.valueOf(mode);
		}catch(Exception e){
			List<MODE> toPrint = Arrays.asList(MODE.values());
			logger.error("The 'mode' parameter is wrong, Have you pass a valid parameter MODE like "+toPrint+"?");
			ExceptionManager.throwWrongParameterException(req, "The 'mode' parameter must be value of "+toPrint, GeonetworkResolver.class, help);
		}

		if(visibility==null){
			logger.error("Path Parameter 'visibility' not found");
			ExceptionManager.throwBadRequestException(req, "Missing mandatory path parameter 'visibility'", GeonetworkResolver.class, help);
		}

		visibility = visibility.toUpperCase();
		try{
			VISIBILITY.valueOf(visibility);
		}catch (Exception e) {
			List<VISIBILITY> toPrint = Arrays.asList(VISIBILITY.values());
			logger.error("The 'visibility' parameter is wrong, Have you pass a valid parameter VISIBILITY like "+toPrint+"?");
			ExceptionManager.throwWrongParameterException(req, "The 'visibility' parameter must be value of "+toPrint, GeonetworkResolver.class, help);
		}

		//HOW TO PASS MORE THAN ONE?
		Map<String,String> filters = new HashMap<String, String>();
		if(filterKey!=null && filterValue!=null){
			filters.put(filterKey, filterValue);
			logger.debug("Added filter parmas to map filters: "+filters);
		}

		String gnCSWlURL = null;
		try {

			GeonetworkServiceInterface gntwAccess = new GeonetworkAccessParameter(scope);
			GeonetworkInstance gnInstance = gntwAccess.getGeonetworkInstance();

			ScopeProvider.instance.set(scope);
			logger.info("set scope provider "+scope);
			Configuration config = gnInstance.getGeonetworkPublisher().getConfiguration();
			Account account = config.getScopeConfiguration().getAccounts().get(Type.CKAN);
			logger.info("CKAN user owner is: "+account.getUser());

//			logger.info("Parameters..");
//		   	for (Enumeration<String> e = req.getParameterNames(); e.hasMoreElements();){
//				String p = e.nextElement();
//			   logger.debug("param "+p + " value "+Arrays.toString(req.getParameterValues(p)));
//		   	}

		   	//DEBUG BODY
//			String readBody = IOUtils.toString(req.getReader());
//			logger.debug("doPost read body request: "+readBody);
			ByteArrayOutputStream byteArray = new ByteArrayOutputStream();

			String geonetworkUrl = config.getGeoNetworkEndpoint();

			// SPECIFIC HANDLER FOR GEONETWORK REQUEST: /srv/en/mef.export
			if(remainPath!=null && remainPath.compareTo(SRV_EN_MEF_EXPORT)==0){
				logger.info("In case of mef.export, perfoming a custom handler");
				gnCSWlURL = geonetworkUrl + SRV_EN_MEF_EXPORT;
				String[] uuidValues = req.getParameterValues(UUID);
				if(uuidValues!=null){
					String data = null;
					for (String uuid : uuidValues) {
						data = UUID+"="+uuid;
					}
					if(data!=null){
						logger.debug("Writing "+data +" into byte array");
						byteArray.write(data.getBytes());
					}else
						IOUtils.copy(req.getInputStream(), byteArray);
				}else
					IOUtils.copy(req.getInputStream(), byteArray);
			}else{
				logger.info("IS NOT A REQUEST TO "+SRV_EN_MEF_EXPORT);
				gnCSWlURL = remainPath==null || remainPath.isEmpty()?geonetworkUrl+"/"+CSW_SERVER:geonetworkUrl+"/"+CSW_SERVER+remainPath;
				IOUtils.copy(req.getInputStream(), byteArray);
			}

			HTTPCallsUtils httpUtils = new HTTPCallsUtils();

			//PRIVATE LAYERS
			if(visibility.equals(VISIBILITY.PRV)){
				logger.info("Visibility: "+VISIBILITY.PRV+" getting private layers..");
				//VRE LAYERS
				if(mode.equals(MODE.VRE)){
					logger.info("Getting "+MODE.VRE+" layers..");
				//HARVESTED LAYERS
				}else{
					filters.put("isHarvested", "y");
					logger.info("Getting "+MODE.HARVEST+" layers, I added 'isHarvested = y' to the filters ["+filters+"]");
				}

				if(account.getUser()!=null){
					boolean authorized = GNAuthentication.login(httpUtils, geonetworkUrl, account.getUser(), account. getPassword());
					logger.info("Authorized on "+geonetworkUrl +" ? "+authorized);
				}else
					logger.info("Skipping authentication, ckan user (the owner) is null");

			//PUBLIC LAYERS
			}else{
				logger.info("Visibility: "+VISIBILITY.PUB+" getting public layers..");
				//VRE LAYERS
				if(mode.equals(MODE.VRE)){
					logger.info("Getting "+MODE.VRE+" layers, the VRE account: "+account.getUser() +" will be used as owner user for filtering... Is it right?");
					filters.put("ownername", account.getUser());
				//HARVESTED LAYERS
				}else{
					//filters.put("isHarvested", "y");
					logger.info("Getting "+MODE.HARVEST+" layers, I'm applying the filters ["+filters+"]");
				}
			}

			logger.info("Sending CSW POST request to URL: "+gnCSWlURL);
			logger.info("Content-Type: "+req.getContentType());

			//DEBUG
			//logger.debug("POST - BODY : "+byteArray.toString());
			InputStream in = httpUtils.post(gnCSWlURL, new ByteArrayInputStream(byteArray.toByteArray()), req.getContentType(), req.getParameterMap());

			if(in==null){
				logger.warn("Input stream returned is null, sending "+HttpServletResponse.SC_NOT_FOUND);
				ExceptionManager.throwNotFoundException(req, "Input stream is null to the request "+gnCSWlURL+ " with body: "+byteArray.toString(), GeonetworkResolver.class, help);
			}

			try{

				ReusableInputStream reus = new ReusableInputStream(in);

				if(visibility.equals(VISIBILITY.PRV)){
					logger.info("Private VISIBILITY requested, retrieving public file identifiers to apply filtering..");
					FilterGetRecords filterGetRecords = new FilterGetRecords(byteArray.toString());
					if(filterGetRecords.getFoundPublicIds()!=null && filterGetRecords.getFoundPublicIds().size()>0){
						logger.info("I'm removing list of public IDs with "+filterGetRecords.getFoundPublicIds().size() +" item/s. Is it right?");
						in = GetResponseRecordFilter.overrideResponseIdsByListIds(reus, filterGetRecords.getFoundPublicIds(), REPLACED_A_PUBLIC_UUID_PLEASE_IGNORE);
					}
				}

				if(filters.size()>0){
					logger.info("Applying filtering on geonet:info... filter/s used: "+filters);
					Document doc = GetResponseRecordFilter.inputStreamToW3CDocument(reus);
					List<String> fileIdentifiers = GetResponseRecordFilter.getTextContentStringsForTagName(doc, "gmd:fileIdentifier");
					List<String> noMatchingFilter = new ArrayList<String>();
					for (String fileId : fileIdentifiers) {

						//CKECKING THE FILTERS
						for (String fkey : filters.keySet()) {
								String value = GetResponseRecordFilter.getMetadataValueByFileIdentifier(fileId, config.getGeoNetworkEndpoint(),config.getAdminAccount().getUser(), config.getAdminAccount().getPassword(), fkey);
								//String own = GetResponseRecordFilter.getMetaOwnerNameByFileIdentifier(fileId, config.getGeoNetworkEndpoint(),config.getAdminAccount().getUser(), config.getAdminAccount().getPassword());
								String fValue = filters.get(fkey);
								//Either the filter KEY doesn't matching any geonet:info (value==null)
								//or the value of filterKey in geonet:info doesn't matching the passed filterValue (value.compareTo(fValue)!=0)
								if(value==null || value.compareTo(fValue)!=0){
									logger.trace(fkey +" of File Identifier "+fileId+" not matching the filter: "+fkey+" with value: "+fValue+", adding it to list to remove file identifier and exit from loop..");
									noMatchingFilter.add(fileId);
									//WHEN I ADD THE FILE IDENTIFIER TO FILTERED ID, I CAN EXIT FROM CKECKING FILTERS LOOP
									break;
								}
						}
					}

					if(noMatchingFilter.size()>0){
						logger.info("Removing "+noMatchingFilter.size()+" layer/s that not macthing the filters: "+filters);
						//Document doc2 = GetResponseRecordFilter.inputStreamToW3CDocument(reus);
						in = GetResponseRecordFilter.overrideResponseIdsByListIds(reus, noMatchingFilter, REPLACED_UUID_BY_FILTER_PLEASE_IGNORE);
						//in = GetResponseRecordFilter.w3CDocumentToInputStream(doc);

					}else{
						logger.info("No replace on UUIDs was applied from filters: "+filters);
						in = reus;
					}

				}

				ReusableInputStream reusIs = new ReusableInputStream(in);

				//END DEBUG
				logger.info("Response return Content-Type: "+httpUtils.getLastContentType());
				return Response
				.ok(reusIs)
				//.header(ConstantsResolver.CONTENT_DISPOSITION,"attachment; filename = \""+fileName+"\"")
				.header(ConstantsResolver.CONTENT_TYPE, httpUtils.getLastContentType()).build();

			}catch(Exception e){
				logger.error("Error on copy the response to send to client: ", e);
				ExceptionManager.throwInternalErrorException(req, "Error on copy the response!", GeonetworkResolver.class, help);
			}finally{
				IOUtils.closeQuietly(in);
			}

		} catch (IllegalArgumentException e){
			logger.error("IllegalArgumentException:", e);
			ExceptionManager.throwBadRequestException(req, "Illegal argument to carry out the request!", GeonetworkResolver.class, help);

		} catch (Exception e) {
			logger.error("Exception:", e);
			String error = "Sorry, an error occurred on resolving geonetwork request with scope "+scope+". Please, contact support!";
			ExceptionManager.throwInternalErrorException(req, error, GeonetworkResolver.class, help);
		}

		//An error occurred
		try {

			throw new InternalServerException(req, javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR, "Error during perform POST operation to: "+gnCSWlURL, GeonetworkResolver.class, new URI(help));
		}
		catch (URISyntaxException e) {
			//silent
			return null;
		}

	}

//	/**
//	 * Purge remain from query string.
//	 *
//	 * @param remain_value the scope
//	 * @param queryString the query string
//	 * @return the string
//	 */
//	private static String purgeRemainFromQueryString(String remain_value, String queryString){
////		SCOPE is: /gcube/devsec/devVRE
////		[INFO ] 2016-04-05 15:01:42,808 org.gcube.datatransfer.resolver.gis.geonetwork.GeonetworkResolver -
////		Query String is: scope=/gcube/devsec/devVRE&version=2.0.2&request=GetCapabilities&service=CSW
//		int start = queryString.indexOf(PATH_PARAM_REMAINPATH+"=");
//
//		if(start>=0){
//			int end = queryString.indexOf("&", start);
//
//			if(end==-1 && queryString.length()==(PATH_PARAM_REMAINPATH+"="+remain_value).length()){ //SCOPE IS THE UNIQUE PARAMETER INTO QUETY STRING
//				logger.debug("Scope is the unique parameter, returning empty query string");
//				return "";
//			}else if(end<queryString.length())
//				return queryString.substring(end+1, queryString.length());
//		}
//
//		return queryString;
//	}

	/**
	 * Discovery geonetwork instance.
	 *
	 * @param scope the scope
	 * @return the geonetwork instance
	 * @throws GeonetworkInstanceException the geonetwork instance exception
	 */
	private GeonetworkInstance discoveryGeonetworkInstance(String scope) throws GeonetworkInstanceException{

		GeonetworkAccessParameter gntwAccess = new GeonetworkAccessParameter(scope);
		return gntwAccess.getGeonetworkInstance(true, null);
	}


//	/**
//	 * Purge scope from query string.
//	 *
//	 * @param scope_value the scope_value
//	 * @param queryString the query string
//	 * @return the string
//	 */
//	private static String purgeScopeFromQueryString(String scope_value, String queryString){
////		SCOPE is: /gcube/devsec/devVRE
////		[INFO ] 2016-04-05 15:01:42,808 org.gcube.datatransfer.resolver.gis.geonetwork.GeonetworkResolver -
////		Query String is: scope=/gcube/devsec/devVRE&version=2.0.2&request=GetCapabilities&service=CSW
//		int start = queryString.indexOf(PATH_PARAM_SCOPE+"=");
//
//		if(start>=0){
//			int end = queryString.indexOf("&", start);
//
//			if(end==-1 && queryString.length()==(PATH_PARAM_SCOPE+"="+scope_value).length()){ //SCOPE IS THE UNIQUE PARAMETER INTO QUETY STRING
//				logger.debug("Scope is the unique parameter, returning empty query string");
//				return "";
//			}else if(end<queryString.length())
//				return queryString.substring(end+1, queryString.length());
//		}
//
//		return queryString;
//	}

	/**
	 * Reset geonetowork instance cache for scope.
	 *
	 * @param scope the scope
	 */
	private void resetGeonetoworkInstanceCacheForScope(String scope){
		if(cacheGNInstances!=null && cacheGNInstances.get(scope)!=null){
			cacheGNInstances.remove(scope);
			logger.info("Reset of "+scope+" in Cache Geonetwork server params perfomed!");
		}else
			logger.info("Reset of "+scope+" in Cache Geonetwork skipped, scope not exists!");
	}



	/**
	 * Purge cache geonetwork instances.
	 */
	private void purgeCacheGeonetworkInstances(){
		cacheGNInstances = new HashMap<String, GeonetworkInstance>();
		logger.info("Reset of GeonetworkInstance cache perfomed!");
	}

	/**
	 * Gets the geonetwork instance for scope.
	 *
	 * @param scope the scope
	 * @return the geonetwork instance for scope
	 * @throws Exception the exception
	 */
	protected GeonetworkInstance getGeonetworkInstanceForScope(String scope) throws Exception{

		if(cacheGNInstances==null)
			purgeCacheGeonetworkInstances();

		scope = ScopeUtil.normalizeScope(scope, "|");
		logger.info("Attempt to get geonetwork instance from GeonetworkInstance cache for scope: "+scope);
		GeonetworkInstance geoInstance = cacheGNInstances.get(scope);

		if(geoInstance==null){
			logger.info("Cache having null GeonetworkInstance for scope "+scope+", reading by Geonetwork library...");
			try {
				geoInstance = discoveryGeonetworkInstance(scope);
				cacheGNInstances.put(scope, geoInstance);
				logger.info("Updated GeonetworkInstance Cache adding couple: Scope "+scope+" - GeonetworkInstance "+geoInstance);
			} catch (Exception e) {
				logger.error("An error occurred on reading GeonetworkInstance for scope "+scope, e);
				throw new Exception("Sorry, An error occurred on reading GeonetworkInstance for scope "+scope);
			}
		}else
			logger.info("GeonetworkInstance cache for scope: "+scope+" is not null using it: "+geoInstance);

		return geoInstance;
	}

}