uri-resolver/src/main/java/org/gcube/datatransfer/resolver/catalogue/CatalogueResolver.java

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

import java.io.IOException;
import java.io.StringReader;
import java.io.UnsupportedEncodingException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.io.IOUtils;
import org.gcube.common.encryption.StringEncrypter;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * The Class GisResolver.
 *
 * @author Francesco Mangiacrapa francesco.mangiacrapa@isti.cnr.it
 * Jan 7, 2016
 */
public class CatalogueResolver extends HttpServlet{

	private static final long serialVersionUID = -8273405286016095823L;

	private static final String TEXT_PALIN_CHARSET_UTF_8 = "text/palin;charset=UTF-8";
	public static final String UTF_8 = "UTF-8";

	/** The logger. */
	private static final Logger logger = LoggerFactory.getLogger(CatalogueResolver.class);

	/* (non-Javadoc)
	 * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
	 */
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

		/*String scope = cer.getValueOfParameter(CatalogueRequestParameter.GCUBE_SCOPE.getKey());
		logger.info("Using scope "+scope+ " to search Ckan Portlet URL from IS");
		ScopeProvider.instance.set(scope);
		String ckanPorltetUrl = CkanPorltetApplicationProfile.getPortletUrlFromInfrastrucure();
		if(ckanPorltetUrl == null || ckanPorltetUrl.isEmpty()){
			sendError(null, HttpStatus.SC_INTERNAL_SERVER_ERROR, "An error occurred during discovery Data Catalogue URL, try again later");
			return;
		}*/

	}


	/* (non-Javadoc)
	 * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
	 */
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

		CatalogueEntityRequest cer = new CatalogueEntityRequest();

		try{
			String jsonRequest = IOUtils.toString(req.getInputStream());

//			jsonRequest = "{" +
//							"\"gcube_scope\" : \"/gcube\"," +
//							"\"entity_context\" : \"dataset\"," +
//							"\"entity_name\" : \"sarda-sarda\"" +
//							"}";
////			String test = "{" +
////							"\"gcube_scope\" : \"/gcube\"," +
////							"\"entity_context\" : \"dataset\"," +
////							"\"entity_name\" : \"sarda-sarda\"," +
////							"\"query\" : {\"key1\" : \"value1\", \"key2\":\"value2\"}" +
//
//
////							"}";

			logger.debug("Read json request: "+jsonRequest);
			JSONObject inputJson = new JSONObject(jsonRequest);

			for (CatalogueRequestParameter parameter : CatalogueRequestParameter.values()) {

			try{

				switch (parameter) {
				case QUERY_STRING:
					//TODO must be implemented
					JSONArray queryString = inputJson.getJSONArray(parameter.getKey());
					break;
				default:
					String value = inputJson.getString(parameter.getKey());
					logger.debug("Read value: "+value+", for parameter: "+parameter.getKey());
					cer.addParameterToRequest(parameter.getKey(), value);
					break;
				}

			}catch(Exception e){
				String error = "";
				try {

					if(parameter.isMandatory()){
						error = parameter.getKey() +" not found";
						sendError(null, HttpStatus.SC_BAD_REQUEST, error);
						return;
					}
					else
						logger.debug("Not Mandatory parameter: "+parameter.getKey()+", not found, I goes on");

				}catch (IOException e1) {
					//silent
				}
			}

			}
		}catch(JSONException e){
			try {
				logger.error("Json passed is malformed: ", e);
				sendError(null, HttpStatus.SC_BAD_REQUEST, "Json passed is malformed");
			}
			catch (IOException e1) {
				//silent
			}
			return;
		}

		try{

			String buildLink = getServletContextURL(req);
			String query = UrlEncoderUtil.encodeQuery(cer.getParameters());
			logger.info("Builded query string: "+query);
			String encriptedQuery = StringEncrypter.getEncrypter().encrypt(query);
			logger.info("Encrypted query: "+encriptedQuery);
			String encodedQuery = base64EncodeStringURLSafe(encriptedQuery);
			buildLink+="?"+encodedQuery;
			logger.info("Writing link: "+buildLink);

			resp.setContentType(TEXT_PALIN_CHARSET_UTF_8);
			resp.setCharacterEncoding(UTF_8);
			resp.getWriter().write(buildLink);

		}catch(Exception e){
			try {
				logger.error("An internal error is occurred: ", e);
				sendError(null, HttpStatus.SC_INTERNAL_SERVER_ERROR, "An error occurred during generating Data Catalogue Link, try again later");
				return;
			}
			catch (IOException e1) {
				//silent
			}
		}

	}

	/**
	 * Send error.
	 *
	 * @param response the response
	 * @param status the status
	 * @param message the message
	 * @throws IOException Signals that an I/O exception has occurred.
	 */
	protected static void sendError(HttpServletResponse response, int status, String message) throws IOException{

		logger.error("error message: "+message);
		logger.info("writing response...");

		if(response==null)
			return;

		response.setStatus(status);
		StringReader sr = new StringReader(message);
		IOUtils.copy(sr, response.getOutputStream());
		logger.info("response writed");
		response.flushBuffer();
	}


	/**
	 * Gets the servlet context url.
	 *
	 * @param req the req
	 * @return the servlet context url
	 */
	public String getServletContextURL(HttpServletRequest req) {

	    String scheme = req.getScheme();             // http
	    String serverName = req.getServerName();     // hostname.com
	    int serverPort = req.getServerPort();        // 80
	    String contextPath = req.getContextPath();   // /mywebapp

	    // Reconstruct original requesting URL
	    StringBuffer url =  new StringBuffer();
	    url.append(scheme).append("://").append(serverName);

	    if (serverPort != 80 && serverPort != 443)
	        url.append(":").append(serverPort);

	    if(contextPath!=null)
	        url.append(":").append(contextPath);

	    String uToS = url.toString();
	    logger.debug("returning servlet context URL: "+uToS);
	    return uToS;
	}

	/**
	 * The main method.
	 *
	 * @param args the arguments
	 */
	public static void main(String[] args) {

	}

	/**
	 * Base64 encode string url safe.
	 *
	 * @param s the s
	 * @return the string
	 */
	public static String base64EncodeStringURLSafe(String s) {

		try {
			return Base64.encodeBase64URLSafeString(s.getBytes(UTF_8));
		}
		catch (UnsupportedEncodingException e) {
			logger.error("Failed to decode the String", e);
			logger.error("Returning input string: " + s);
			return s;
		}
	}
}