/* Utilities that manipulate strings using XSLT.

 Copyright (c) 2002-2014 The Regents of the University of California.
 All rights reserved.
 Permission is hereby granted, without written agreement and without
 license or royalty fees, to use, copy, modify, and distribute this
 software and its documentation for any purpose, provided that the above
 copyright notice and the following two paragraphs appear in all copies
 of this software.

 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
 SUCH DAMAGE.

 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
 ENHANCEMENTS, OR MODIFICATIONS.

 PT_COPYRIGHT_VERSION_2
 COPYRIGHTENDKEY

 */
package ptolemy.util;

import java.io.ByteArrayOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URL;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.ErrorListener;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

///////////////////////////////////////////////////////////////////
//// XSLTUtilities

/**
 A collection of utilities for manipulating strings using XSLT.
 These utilities do not depend on any other ptolemy.* packages.

 <p>This file uses Saxon, the XSLT and XQuery Processor
 <a href="http://saxon.sourceforge.net/#in_browser" target="_top">http://saxon.sourceforge.net</a>.

 <p>Between Java 1.4.x and Java 1.5, Xalan was removed from the jar
 files that are shipped.  Since Caltrop uses Saxon anyway, we now
 use Saxon here as well.


 @author Christopher Hylands, Haiyang Zheng
 @version $Id: XSLTUtilities.java 70402 2014-10-23 00:52:20Z cxh $
 @since Ptolemy II 2.1
 @Pt.ProposedRating Green (eal)
 Pending Java 1.5 changes
 @Pt.AcceptedRating Yellow (cxh)
 */
public class XSLTUtilities {
    /** Instances of this class cannot be created.
     */
    private XSLTUtilities() {
    }

    ///////////////////////////////////////////////////////////////////
    ////                         public methods                    ////

    /** Apply XSL transforms to an input file and generate an output file.
     *  <p>Example use:
     * <pre>
     *  java -classpath $PTII ptolemy.util.XSLTUtilities
     *       $PTII/ptolemy/hsif/demo/SwimmingPool/SwimmingPool.xml \
     *       $PTII/ptolemy/hsif/xsl/GlobalVariablePreprocessor.xsl \
     *       exportMoMLDTD \
     *       /tmp/SwimmingPool_1.xml
     * </pre>

     * @param args At least three arguments:
     * <ul>
     * <li> The first argument is the input file name.
     * <li> The second through n-1 arguments are the named xsl files.
     * <li> The final argument is the output file name.
     * @exception Exception If there are problems with the transform.
     */
    public static void main(String[] args) throws Exception {

        String lastArg = args[args.length - 1];
        String outputFileName = lastArg;
        int numberOfTransformers = args.length - 2;
        if (lastArg.compareTo("exportMoMLDTD") == 0) {
            _exportDTD = true;
            outputFileName = args[args.length - 2];
            numberOfTransformers = args.length - 3;
        } else {
            _exportDTD = false;
        }

        if (_exportDTD && args.length < 4 || !_exportDTD && args.length < 3) {
            System.err.println("Usage: java -classpath $PTII "
                    + "ptolemy.util.XSLTUtilities inputFile "
                    + "xslFile1 [xslFile2 . . .] outputFile "
                    + "[exportMoMLDTD]");
            StringUtilities.exit(2);
        }

        // Make sure we can write the output first
        FileWriter fileWriter = null;

        try {
            fileWriter = new FileWriter(outputFileName);

            Document inputDocument = parse(args[0]);

            List transforms = new LinkedList();

            for (int i = 1; i < numberOfTransformers + 1; i++) {
                transforms.add(args[i]);
            }

            Document outputDocument = XSLTUtilities.transform(inputDocument,
                    transforms);
            _writeOutput(XSLTUtilities.toString(outputDocument), fileWriter);
        } finally {
            if (fileWriter != null) {
                fileWriter.close();
            }
        }
    }

    /** Parse an XML document using Saxon.
     *  @param filename The file name of the xml file to be read in
     *  The filename is passed to org.xml.sax.InputSource(String),
     *  so it may be a file name or a URL.
     *  @return the parsed document.
     *  @exception ParserConfigurationException If there is a problem
     *  creating the DocumentBuilder.
     *  @exception IOException If the filename could not be parsed.
     */
    public static Document parse(String filename)
            throws ParserConfigurationException, IOException {
        // FIXME: Throw something other than Exception
        //        System.setProperty("javax.xml.parsers.DocumentBuilderFactory",
        //                "net.sf.saxon.om.DocumentBuilderFactoryImpl");

        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();

        // We use InputSource here so that we can specify the filename
        // argument as a jar url so that HSIFToMoML works under Web Start.
        try {
            return builder.parse(new InputSource(filename));
        } catch (SAXException ex) {
            // Rethrow this with the filename included.
            IOException exception = new IOException("Failed to parse '"
                    + filename + "'");
            exception.initCause(ex);
            throw exception;
        }
    }

    /** Set the flag indicating whether to export DTD specification when
     *  transforming XML files. By default, the transformer does not export
     *  DTD.
     *  @param exportDTD True for export DTD, false for not.
     */
    public static void setExportDTD(boolean exportDTD) {
        _exportDTD = exportDTD;
    }

    /** Given a Document, generate a String.
     *  @param document The document to be converted to a string.
     *  @return A string representation of the Document.
     *  @exception TransformerException If there is a
     *  a problem creating a new Transformer or parser.
     *  @exception IOException If there is a problem closing the output
     *  stream.
     */
    public static String toString(Document document)
            throws TransformerException, IOException {
        // FIXME: Joern's sample code had this in it, but if we
        // include it, then we get Provider   not found errors
        //String defaultDBFI =
        //    System.getProperty("javax.xml.parsers.DocumentBuilderFactory");
        //System.setProperty("javax.xml.parsers.DocumentBuilderFactory",
        //                   defaultDBFI == null ? "" : defaultDBFI);
        OutputStream outputStream = null;

        try {
            outputStream = new ByteArrayOutputStream();

            StreamResult result = new StreamResult(outputStream);
            TransformerFactory transformerFactory = TransformerFactory
                    .newInstance();
            Transformer serializer = transformerFactory.newTransformer();
            serializer.transform(new DOMSource(document), result);
            return outputStream.toString();
        } finally {
            if (outputStream != null) {
                outputStream.close();
            }
        }
    }

    /** Transform a document.
     *  @param inputDocument The Document to be transformed
     *  @param xslFileName The file name of the xsl file to be used.
     *  If the file cannot be found, then we look up the file in the classpath.
     *  @return a transformed document
     *  @exception TransformerException If there is a problem with the
     *  transform.
     *  @exception IOException If there is a problem finding the
     *  transform file.
     */
    public static Document transform(Document inputDocument, String xslFileName)
            throws TransformerException, IOException {
        TransformerFactory transformerFactory = TransformerFactory
                .newInstance();
        // Use an ErrorListener so as to avoid error output on stderr
        // which causes problems with the test harness
        transformerFactory.setErrorListener(new ErrorListener() {
            /** Receive notification of a recoverable error. */
            @Override
            public void error(TransformerException exception)
                    throws TransformerException {
                throw exception;
            }

            /** Receive notification of a non-recoverable error. */
            @Override
            public void fatalError(TransformerException exception)
                    throws TransformerException {
                throw exception;
            }

            /** Receive notification of a warning. */
            @Override
            public void warning(TransformerException exception) {
                System.err.println("ptolemy.util.XSLTUtilities.transform()"
                        + ": Warning: " + exception);
            }
        });
        Transformer transformer = null;

        // Set a valid transformer.
        try {
            transformer = transformerFactory.newTransformer(new StreamSource(
                    xslFileName));
        } catch (javax.xml.transform.TransformerConfigurationException ex) {
            try {
                // We might be in the Swing Event thread, so
                // Thread.currentThread().getContextClassLoader()
                // .getResource(entry) probably will not work.
                Class refClass = Class.forName("ptolemy.util.XSLTUtilities");
                URL entryURL = refClass.getClassLoader().getResource(
                        xslFileName);

                if (entryURL != null) {
                    transformer = transformerFactory
                            .newTransformer(new StreamSource(entryURL
                                    .toString()));
                } else {
                    IOException exception = new IOException("Failed to open '"
                            + xslFileName + "'");
                    exception.initCause(ex);
                    throw exception;
                }
            } catch (Exception ex2) {
                IOException exception = new IOException("Failed to open \""
                        + xslFileName + "\".\n"
                        + "Searching the classpath threw:\n" + ex2);
                exception.initCause(ex);
                throw exception;
            }
        }

        DOMResult result = new DOMResult();
        transformer.transform(new DOMSource(inputDocument), result);
        return (Document) result.getNode();
    }

    /** Transform a document by applying a list of transforms.
     *  @param inputDocument The Document to be transformed
     *  @param xslFileNames A list of Strings naming the
     *  xsl files to be applied sequentially.
     *  @return a transformed document
     *  @exception TransformerException If there is a
     *  a problem creating a new Transformer or parser.
     *  @exception IOException If there is a problem closing the output
     *  stream.
     */
    public static Document transform(Document inputDocument, List xslFileNames)
            throws TransformerException, IOException {
        Iterator fileNames = xslFileNames.iterator();

        while (fileNames.hasNext()) {
            String fileName = (String) fileNames.next();
            inputDocument = transform(inputDocument, fileName);
        }

        return inputDocument;
    }

    /** Transform a file by applying a list of XSL transforms.
     *  @param input The XML to be transformed
     *  @param fileWriter A FileWriter that will write to the MoML
     *  file.  The caller of this method is responsible for closing
     *  the the FileWriter.
     *  @param xslFileNames A list of Strings naming the
     *  xsl files to be applied sequentially.
     *  @exception ParserConfigurationException If there is a problem
     *  creating the DocumentBuilder.
     *  @exception TransformerException If there is a
     *  a problem with the transform.
     *  @exception IOException If there is a problem
     *  finding a transform file or applying a transform.
     */
    public static void transform(String input, FileWriter fileWriter,
            List xslFileNames) throws ParserConfigurationException,
            TransformerException, IOException {
        // This method takes a FileWriter so that the user can
        // ensure that the FileWriter exists and is writable before going
        // through the trouble of doing the conversion.
        Document inputDocument = null;

        try {
            inputDocument = XSLTUtilities.parse(input);
        } catch (IOException ex) {
            // net.sf.saxon.om.DocumentBuilderImpl.parse()
            // can throw a javax.xml.transform.TransformerException
            // which extends Exception, but has  IOException as a cause,
            // so we must catch Exception here, not IOException.
            // Try it as a jar url
            try {
                URL jarURL = ClassUtilities.jarURLEntryResource(input);

                if (jarURL == null) {
                    throw new IOException("'" + input + "' was not a jar "
                            + "URL, or was not found");
                }

                inputDocument = XSLTUtilities.parse(jarURL.toString());
            } catch (IOException ex2) {
                // Rethrow the original exception
                throw ex;
            }
        }

        Document outputDocument = XSLTUtilities.transform(inputDocument,
                xslFileNames);

        _writeOutput(XSLTUtilities.toString(outputDocument), fileWriter);

        // Let the caller close the fileWriter.
        //fileWriter.close();
    }

    ///////////////////////////////////////////////////////////////////
    ////                         private methods                   ////

    private static void _writeOutput(String outputString, FileWriter fileWriter)
            throws IOException {
        if (_exportDTD) {
            // XSLT discards the DTD decalration.
            // The following code inserts the specified DTD decalrations.
            // Write the following into the filewriter first:
            // <?xml version="1.0" encoding="UTF-8"?>,
            // which appears just before the comment, <!--
            int positionToInsertDTD = outputString.indexOf("<!--");
            fileWriter.write(outputString, 0, positionToInsertDTD);
            // FIXME: So far, only MoML DTD can be exported. If the support
            // of more DTDs is necessray, modify the main() method and
            // setExportDTD() method to allow configuration of DTD.
            fileWriter
            .write("\r\n<!DOCTYPE entity PUBLIC \"-//UC Berkeley//DTD MoML 1//EN\" "
                    + "\r\n\"http://ptolemy.eecs.berkeley.edu/xml/dtd/MoML_1.dtd\">");
            fileWriter.write(outputString.substring(positionToInsertDTD));
        } else {
            fileWriter.write(outputString);
        }
    }

    ///////////////////////////////////////////////////////////////////
    ////                         private variables                 ////

    private static boolean _exportDTD = false;
}