/**
 * SiRPACServlet - Simple RDF Parser & Compiler Servlet wrapper
 *
 * Copyright © World Wide Web Consortium, (Massachusetts Institute of
 * Technology, Institut National de Recherche en Informatique et en
 * Automatique, Keio University).
 *
 * All Rights Reserved.
 *
 * Please see the full Copyright clause at
 * <http://www.w3.org/Consortium/Legal/copyright-software.html>
 *
 * This servlet is a wrapper for the SiRPAC RDF parser.  The servlet 
 * expects two incoming variables through the POST method:
 *
 * 1. The RDF/XML document via the 'RDF' variable
 * 2. The checkbox status via the 'BAGS' variable (='on' when activated)
 *
 * @author Janne Saarela <jsaarela@w3.org>
 *
 * Major re-write to support AT&T GraphVis tool by Arthur Barstow 
 * <barstow@w3.org>
 */

package org.w3c.rdf.examples;

import java.io.*;
import java.util.StringTokenizer;
import java.util.Enumeration;
import javax.servlet.*;
import javax.servlet.http.*;

import org.xml.sax.InputSource;
import org.xml.sax.Parser;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.*;

import org.w3c.rdf.model.*;
import org.w3c.rdf.syntax.*;
import org.w3c.rdf.syntax.RDFConsumer;
import org.w3c.rdf.util.xml.DumpConsumer;
import org.w3c.rdf.util.xml.ErrorStore;
import org.w3c.rdf.implementation.model.StatementImpl;
import org.w3c.rdf.implementation.model.NodeFactoryImpl;
import org.w3c.rdf.implementation.syntax.sirpac.*;

public class SiRPACServlet extends HttpServlet
{
    final static public String	REVISION = "$Id: SiRPACServlet.java,v 1.3 2000/10/05 03:56:30 barstow Exp $";

    // @@ 
    private static final String MAIL_TO = "barstow@mediaone.net";
 
    // Names of the servlet's parameters
    private static final String SIRPAC_TMP_DIR = "SIRPAC_TMP_DIR";
    private static final String DOT_PATH = "DOT_PATH";
    private static final String DOT_LIB_DIR = "DOT_LIB_DIR";
    private static final String DOT_FONT_DIR = "DOT_FONT_DIR";

    // Variables for the servlet's parameters
    private static String m_SiRPACTmpDir = null;
    private static String m_DotPath = null;
    private static String m_DotFontDir = null;
    private static String m_DotLibDir = null;

    // The parser
    private SiRPAC	  m_sirpac = null;
    // The error handler
    private ErrorStore    m_errorHandler;

    /*
     * Create a temporary PrintWriter object
     *
     *@return a PrintWriter object if a temporary file is created; 
     *  null otherwise
     */
/*
    private String getTempFileName (PrintWriter pw) {
    }
*/

    /*
     * Generate a graph of the RDF data model
     *
     *@param out
     *@param rdf
     *@param req
     */
    private void generateGraph (ServletOutputStream out, String rdf, HttpServletRequest req) {
        try {
            out.println("<hr title=\"visualisation\">");
            out.println("<h3>Graph of the data model</h3>");

            // No need to continue if any of the parameters are missing
            if (m_SiRPACTmpDir == null || m_DotPath == null || 
                m_DotFontDir == null || m_DotLibDir == null) { 
                out.println("Servlet initialization failed.  A graph cannot be generated.");
                return;
            } 

            // Must generate a unique file name that the Dot consumer
            // will use

            File f;
            try {
                 File d = new File(m_SiRPACTmpDir);
                 f = File.createTempFile("sirpac_", ".dot", d);
            } catch (Exception e) {
                out.println("Failed to create a temporary file. A graph cannot be generated (" + e.getMessage() + ").");
                return;
            }

            // Create a PrintWriter for the GraphViz consumer
            FileWriter fw = new FileWriter(f);
            PrintWriter pw = new PrintWriter(fw);

            // Run the parser using the DOT consumer to capture
            // the output in a file
	    StringReader         sr = new StringReader (rdf);
	    InputSource	         is = new InputSource (sr);
            GraphVizDumpConsumer consumer = new GraphVizDumpConsumer(pw);

	    try {
                m_sirpac.parse(is, consumer);
	    } catch (Exception e) {
                out.println("An attempt to generate the graph data failed ("
                            + e.getMessage() + ").");
                return;
	    }

            // Pass the DOT data file to the GraphViz dot program
            // to create the GIF file
            String dotFileName = f.getAbsolutePath();

            // Close the file
            pw.close();

            // @@ Delete the DOT file


           // @@ Delete the GIF file

out.println("<img src=\"http://localhost:8001/servlet/SiRPAC.tmp/1.gif\"/>");

        } catch (Exception e) {
            System.err.println("Exception: " + e.getMessage());
        }
    }

    /*
     * Search the given string for substring "key"
     * and if it is found, replace it with string "replacement"
     *
     *@return if no substitutions are done, input is returned; otherwise 
     * a new string is returned.
     */
    private String replaceString(String input, String key, String replacement) {
        StringBuffer sb = new StringBuffer("");
        StringTokenizer st = new StringTokenizer(input, key);

        // Must handle the case where the input string begins with the key
        if (input.startsWith(key))
            sb = sb.append(replacement);
        while (st.hasMoreTokens()) {
            sb = sb.append(st.nextToken());
            if (st.hasMoreTokens())
                sb = sb.append(replacement);
        }
        if (sb.length() >= 1)
            return sb.toString();
        else
            return input;
    }

    /*
     * Print the document's header info
     *
     *@param out the servlet's output stream
     */
    private void printDocumentHeader (ServletOutputStream out) {

        try {

            out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 Transitional//EN\"");
            out.println("      \"http://www.w3.org/TR/REC-html40/loose.dtd\">");
            out.println("<HTML><HEAD>");
            out.println("<TITLE>RDF creation</TITLE>");
            out.println("<LINK HREF=\"rdf.css\" REL=\"stylesheet\">");
            out.println("</HEAD>");
            out.println("<BODY>");

        } catch (Exception e) {
            System.err.println("Exception: " + e.getMessage());
        }
    }

    /*
     * Print the rdf listing
     *
     *@param out the servlet's output stream
     *@param rdf the RDF code
     */
    private void printListing (ServletOutputStream out, String rdf) {
        try {
            out.println("<hr title=\"original source\">");
            out.println("<h3>The original RDF/XML document</h3>");
            out.println("<pre>");

            String s = replaceString(rdf, "<", "&lt;");
            StringTokenizer st = new StringTokenizer(s, "\n");

            // Now output the RDF one line at a time with line numbers
            int lineNum = 1;
            while (st.hasMoreTokens()) {
                out.print ("<a name=\"" + lineNum + "\">" + lineNum +
                          "</a>: " + st.nextToken());
                lineNum++;
            }

            out.println("</pre>");
        } catch (Exception e) {
            System.err.println("Exception: " + e.getMessage());
        }
    }

    /*
     * Print the header for the triple listing
     *
     *@param out the servlet's output stream
     */
    private void printTripleHeader (ServletOutputStream out) {
        try {
            out.println("<hr title=\"triples\">");
            out.println("<h3>Triples of the data model</h3>");
            
            // The output for each triple will be pre-formatted
            out.println("<pre>");
        } catch (Exception e) {
            System.err.println("Exception: " + e.getMessage());
        }
    }

    /*
     * Print the footer info for the triple listing
     *
     *@param out the servlet's output stream
     */
    private void printTripleFooter (ServletOutputStream out) {
        try {
            out.println("</pre>");
        } catch (Exception e) {
            System.err.println("Exception: " + e.getMessage());
        }
    }

    /*
     * Print the document's footer info
     *
     *@param out the servlet's output stream
     *@param rdf the RDF code
     */
    private void printDocumentFooter (ServletOutputStream out, String rdf) {
        try {

            out.println("<hr title=\"Problem reporting\">");
            out.println("<h3>Feedback</h3>");
            out.println("<p>If you suspect that SiRPAC produced an error, please enter an explanation below and then press the <b>Submit problem report</b> button, to mail the report (and listing) to <i>" + MAIL_TO + "</i></p>");
            out.println("<form enctype=\"text/plain\" method=\"post\" action=\"mailto:" + MAIL_TO + "\">");
            out.println("<textarea cols=\"60\" rows=\"4\" name=\"report\"></textarea>");
            out.println("<p><input type=\"hidden\" name=\"RDF\" value=\"&lt;?xml version=&quot;1.0&quot;?>");

            // The listing is being passed as a parameter so the '<' 
            // and '"' characters must be replaced with &lt; and &quot, 
            // respectively
            String s1 = replaceString(rdf, "<", "&lt;");
            String s2 = replaceString(s1,  "\"", "&quot;");
            out.println(s2 + "\">");

            out.println("<input type=\"submit\" value=\"Submit problem report\">");
            out.println("</form>");
            out.println("<hr><a href=\"/description\">Back</a> to main page.");
            out.println("</BODY>");
            out.println("</HTML>");

        } catch (Exception e) {
            System.err.println("Exception: " + e.getMessage());
        }

    }

    /*
     * Servlet's get info method
     */
    public String getServletInfo () {
	return "Servlet Wrapper for SiRPAC. This is revision " + REVISION;
    }

    /*
     * Servlet's init method
     *
     *@param config the servlet's configuration object
     */
    public void init(ServletConfig config) throws ServletException {
	super.init (config);

	m_sirpac = new SiRPAC();
        m_errorHandler = new ErrorStore();
        m_sirpac.setErrorHandler(m_errorHandler);

        // Cache the parameters
        m_SiRPACTmpDir = config.getInitParameter(SIRPAC_TMP_DIR);
        m_DotPath = config.getInitParameter(DOT_PATH);
        m_DotFontDir = config.getInitParameter(DOT_FONT_DIR);
        m_DotLibDir = config.getInitParameter(DOT_LIB_DIR);
    }

    /*
     * Servlet's destroy info method
     */
    public void destroy () {
	super.destroy ();
    }

    /*
     * Servlet's doGet info method
     *
     *@param req the request
     *@param res the response
     */
    public void doGet (HttpServletRequest req, HttpServletResponse res)
        throws ServletException, IOException {

	ServletOutputStream out = res.getOutputStream ();

	res.setContentType ("text/html");

	out.println ("<h1>GET is NOT supported!</h1>\n\n<p>Please send RDF through POST!</p>\n");
    }

    /*
     * Servlet's doPost method
     *
     *@param req the request
     *@param res the response
     */
    public void doPost (HttpServletRequest req, HttpServletResponse res)
        throws ServletException, IOException {

	ServletOutputStream out = res.getOutputStream ();

	String		             sRDF = req.getParameter ("RDF");
	String		             sBags = req.getParameter ("BAGS");
	StringReader	             sr = new StringReader (sRDF);
	InputSource	             is = new InputSource (sr);
        boolean                      error = false;
        SiRPACServletDumpConsumer    consumer = new SiRPACServletDumpConsumer();

        printDocumentHeader (out);
        printListing (out, sRDF);
        printTripleHeader (out);

	try {
            // Override the default triple output handler
            consumer.setOutputStream(out);

	    if (sBags != null && sBags.equals ("on"))
		m_sirpac.createBags (true);

            m_sirpac.parse(is, consumer);

            generateGraph(out, sRDF, req);

	} catch (SAXException e) {
            error = true;
	} catch (Exception e) {
            error = true;
	    e.printStackTrace ();
	}

        printTripleFooter(out);

	res.setContentType ("text/html");

	if (error) {
	    out.println ("<h1>Errors during parsing</h1>\n");
            out.println ("<pre>\n");

            // Make the line number a link to the listing
            out.println ("Fatal error: " + m_errorHandler.getErrorMessage());
            out.println ("   (Line number = " + "<a href=\"#" + 
                         m_errorHandler.getLineNumber() + "\">" + 
                         m_errorHandler.getLineNumber() + "</a>" +
                         ", Column number = " + 
                         m_errorHandler.getColumnNumber() + ")");

	    out.println ("</pre>\n\n");
	}

        printDocumentFooter(out, sRDF);
    }
}