/*
 * This file is part of rasdaman community.
 *
 * Rasdaman community is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Rasdaman community is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with rasdaman community.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Copyright 2003 - 2010 Peter Baumann / rasdaman GmbH.
 *
 * For more information please see <http://www.rasdaman.org>
 * or contact Peter Baumann via <baumann@rasdaman.com>.
 */
package petascope.wcps.server.servlet;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import petascope.core.DbMetadataSource;
import petascope.wcps.server.core.ProcessCoveragesRequest;
import petascope.wcps.server.core.WCPS;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;
import java.util.Properties;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;

//important limitation: this will only return the first result if several are available.
//The reason is that WCPS currently has no standardized way to return multiple byte streams to
//the user.
//This is the servlet interface of WCPS. It mostly consists of sanity checks and initialization,
//the meat is onyl a few lines. The WCPS class does the actual work.
public class WCPSServlet extends HttpServlet {

    private Properties dbParams;
    private DbMetadataSource metadataSource;
    private String rasdamanDatabase;
    private String rasdamanUrl;
    private WCPS wcps;
    // path to the default HTML response of the servlet
    private String servletHtmlPath = "/templates/wcps-servlet.html";
    // String containing the HTML code for the default response
    private String defaultHtmlResponse;

    public void init() throws ServletException {
        try {
            dbParams = new Properties();
            System.out.println("WCPS: loading database properties");
            dbParams.load(
                    new FileInputStream(
                    getServletContext().getRealPath("/settings.properties")));
            rasdamanUrl = dbParams.getProperty("rasdaman_url");
            rasdamanDatabase = dbParams.getProperty("rasdaman_database");

            System.out.println("WCPS: initializing metadata database");
            metadataSource =
                    new DbMetadataSource(dbParams.getProperty("metadata_driver"),
                    dbParams.getProperty("metadata_url"),
                    dbParams.getProperty("metadata_user"),
                    dbParams.getProperty("metadata_pass"), false);

            System.out.println("WCPS: initializing WCPS core");
            wcps = new WCPS(
                    new File(getServletContext().getRealPath("/xml/ogc/wcps/1.0.0/wcpsProcessCoverages.xsd")),
                    //                        new CachedMetadataSource(metadataSource));    // removed metadata caching (andrei)
                    metadataSource);

            servletHtmlPath = getServletContext().getRealPath(servletHtmlPath);
            defaultHtmlResponse = FileUtils.readFileToString(new File(servletHtmlPath));

            System.out.println("WCPS: initialization complete");
        } catch (Exception e) {
            System.out.println("WCPS: initialization error");
            System.out.println("WCPS: closing metadata database");

            if (metadataSource != null) {
                metadataSource.close();
            }

            System.out.println("WCPS: done with init error");
            throw new ServletException("WCPS initialization error", e);
        }

    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        System.out.println("WCPS: invoked with GET");
        printUsage(response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        System.out.println("WCPS: invoked with POST");
        OutputStream webOut = null;

        try {
            String xmlRequest = null;

            if (ServletFileUpload.isMultipartContent(request)) {
                @SuppressWarnings("unchecked")
                Iterator<FileItem> fileItems =
                        (Iterator<FileItem>) (new ServletFileUpload(
                        new DiskFileItemFactory())).parseRequest(
                        request).iterator();

                if (!fileItems.hasNext()) {
                    throw new IOException(
                            "Multipart POST request contains no parts");
                }

                FileItem fileItem = fileItems.next();

                if (fileItems.hasNext()) {
                    throw new IOException(
                            "Multipart POST request contains too many parts");
                }

                if (!fileItem.isFormField()
                        && fileItem.getContentType().equals("text/xml")) {
                    xmlRequest = fileItem.getString();
                }

                if (xmlRequest == null) {
                    System.out.println(
                            "WCPS: no XML file was uploaded within multipart POST request");
                    printUsage(response);
                    return;
                }

                System.out.println(
                        "WCPS: received XML via a multipart POST request");
            } else {
                String xml = request.getParameter("xml");
                String query = request.getParameter("query");

                if (xml != null) {
                    System.out.println("WCPS: received XML via a 'xml' parameter in a POST request");
                    xmlRequest = xml;
                } else if (query != null) {
                    System.out.println("WCPS: received the following  query via a 'query' "
                            + "parameter in a POST request:");
                    System.out.println(query);

                    xmlRequest = ProcessCoveragesRequest.abstractQueryToXmlQuery(query);
                    System.out.println("WCPS: transformed the abstract syntax query into an XML query!");
                } else {
                    System.out.println("WCPS: no request was received");
                    printUsage(response);
                    return;
                }
            }

            System.out.println("WCPS: received the following request:");
            System.out.println(xmlRequest);

            System.out.println("WCPS: preparing request");
            ProcessCoveragesRequest processCoverageRequest =
                    wcps.pcPrepare(rasdamanUrl, rasdamanDatabase, IOUtils.toInputStream(xmlRequest));

            String query = processCoverageRequest.getRasqlQuery();
            String mime = processCoverageRequest.getMime();

            System.out.println("[" + mime + "] " + query);

            System.out.println("Resulting RasQL query: " + query);

            System.out.println("WCPS: executing request");

            List<byte[]> results = processCoverageRequest.execute();

            System.out.println("WCPS: setting response mimetype to " + mime);
            response.setContentType(mime);
            System.out.println("WCPS: returning response");
            webOut = response.getOutputStream();
            webOut.write(results.get(0));
            System.out.println("WCPS: done");
        } catch (Exception e) {
            printError(response, "Error: " + e.getMessage(), e);
        } finally {
            if (webOut != null) {
                try {
                    webOut.close();
                } catch (IOException e) {
                }
            }
        }
    }

    public void destroy() {
        super.destroy();

    }

    public String getServletInfo() {
        return "Web Coverage Processing Service (Project PetaScope)";

    }

    private void printError(HttpServletResponse response, String message, Exception e)
            throws IOException {
        System.out.println("WCPS: error");
        System.out.println("WCPS: setting response mimetype to text/html; charset=utf-8");
        response.setContentType("text/html; charset=utf-8");
        System.out.println("WCPS: returning the following error message");
        e.printStackTrace(System.out);
        System.out.println("WCPS: end of error message");
        PrintWriter out = new PrintWriter(response.getOutputStream());

        out.println(
                "<html><head><title>Web Coverage Processing Service</title></head><body>");
        out.println("<h1>An error has occured</h1>");
        out.println("<p>" + message + "</p>");
        out.println("<p>Stack trace:<br/><small>");
        e.printStackTrace(out);
        out.println("</small></p></body></html>");
        out.close();
        System.out.println("WCPS: done with error");
    }

    private void printUsage(HttpServletResponse response) throws IOException {
        System.out.println("WCPS: setting response mimetype to text/html; charset=utf-8");
        System.out.println("WCPS: returning usage message");
        response.setContentType("text/html; charset=utf-8");
        PrintWriter out = new PrintWriter(response.getOutputStream());

        out.println(defaultHtmlResponse);

        out.close();
        System.out.println("WCPS: done nothing");

    }
}