/*
 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
 */
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.qetest.xslwrapper;

import java.io.ByteArrayOutputStream;
import java.io.FileOutputStream;
import java.util.Properties;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.Templates;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.sax.SAXResult;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.sax.SAXTransformerFactory;
import javax.xml.transform.sax.TemplatesHandler;
import javax.xml.transform.sax.TransformerHandler;
import javax.xml.transform.stream.StreamResult;
import static jaxp.library.JAXPTestUtilities.filenameToURL;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

/**
 * Implementation of TransformWrapper that uses the TrAX API and uses
 * SAXSource/SAXResult whenever possible.
 * This implementation uses SAX to build the stylesheet and to perform the
 * transformation.
 * <p><b>Important!</b> The underlying System property of
 * javax.xml.transform.TransformerFactory will determine the actual TrAX
 * implementation used. This value will be reported out in our
 * getProcessorInfo() method.</p>
 *
 */
public class TraxSAXWrapper extends TransformWrapperHelper {

    /**
     * TransformerFactory to use; constructed in newProcessor().
     */
    private TransformerFactory factory;

    /**
     * SAXTransformerFactory we actually use; constructed in newProcessor().
     */
    private SAXTransformerFactory saxFactory;

    /**
     * Templates to use for buildStylesheet().
     */
    private Templates builtTemplates;

    /**
     * Cached copy of newProcessor() properties.
     */
    protected Properties newProcessorOpts = null;

    /**
     * Get a general description of this wrapper itself.
     *
     * @return Uses TrAX to perform transforms from SAXSource(systemId)
     */
    public String getDescription() {
        return "Uses TrAX to perform transforms from SAXSource(stream)";
    }

    /**
     * Get a specific description of the wrappered processor.
     *
     * @return specific description of the underlying processor or transformer
     * implementation: this should include both the general product name, as
     * well as specific version info. If possible, should be implemented without
     * actively creating an underlying processor.
     */
    @Override
    public Properties getProcessorInfo() {
        Properties p = TraxWrapperUtils.getTraxInfo();
        p.put("traxwrapper.method", "sax");
        p.put("traxwrapper.desc", getDescription());
        return p;
    }

    /**
     * Actually create/initialize an underlying processor or factory.
     *
     * For TrAX/javax.xml.transform implementations, this creates a new
     * TransformerFactory.
     *
     * @param options Hashtable of options, unused.
     *
     * @return (Object)getProcessor() as a side-effect, this will be null if
     * there was any problem creating the processor OR if the underlying
     * implementation doesn't use this
     * @throws javax.xml.transform.TransformerConfigurationException when 
     * actual implementation doesn't support StreamSource or StreamResult.
     */
    @Override
    public TransformerFactory newProcessor(Properties options) throws TransformerConfigurationException {
        newProcessorOpts = options;
        reset(false);
        factory = TransformerFactory.newInstance();
        // Verify the factory supports SAX!
        if (!(factory.getFeature(SAXSource.FEATURE)
                && factory.getFeature(SAXResult.FEATURE))) {
            throw new TransformerConfigurationException("TraxSAXWrapper.newProcessor: factory does not support SAX!");
        }
        // Set any of our options as Attributes on the factory
        TraxWrapperUtils.setAttributes(factory, options);
        saxFactory = (SAXTransformerFactory) factory;
        return saxFactory;
    }

    /**
     * Transform supplied xmlName file with the stylesheet in the xslName file
     * into a resultName file using SAX.
     *
     * Pseudocode:      <code>
     *   // Read/build stylesheet
     *   xslReader.setContentHandler(templatesHandler);
     *   xslReader.parse(xslName);
     *
     *   xslOutputProps = templates.getOutputProperties();
     *   // Set features and tie in DTD, lexical, etc. handling
     *
     *   serializingHandler.getTransformer().setOutputProperties(xslOutputProps);
     *   serializingHandler.setResult(new StreamResult(outBytes));
     *   stylesheetHandler.setResult(new SAXResult(serializingHandler));
     *   xmlReader.setContentHandler(stylesheetHandler);
     *   // Perform Transform
     *   xmlReader.parse(xmlName);
     *   // Separately: write bytes to disk
     * </code>
     *
     * @param xmlName local path\filename of XML file to transform
     * @param xslName local path\filename of XSL stylesheet to use
     * @param resultName local path\filename to put result in
     *
     * @throws Exception any underlying exceptions from the wrappered processor
     * are simply allowed to propagate; throws a RuntimeException if any other
     * problems prevent us from actually completing the operation
     */
    @Override
    public void transform(String xmlName, String xslName, String resultName)
            throws Exception {
        preventFootShooting();

        // Create a ContentHandler to handle parsing of the xsl
        TemplatesHandler templatesHandler = saxFactory.newTemplatesHandler();

        // Create an XMLReader and set its ContentHandler.
        // Be sure to use the JAXP methods only!
        XMLReader xslReader = getJAXPXMLReader();
        xslReader.setContentHandler(templatesHandler);

        // read/build Templates from StreamSource
        xslReader.parse(filenameToURL(xslName));

        // Get the Templates object from the ContentHandler.
        Templates templates = templatesHandler.getTemplates();
        // Get the outputProperties from the stylesheet, so
        //  we can later use them for the serialization
        Properties xslOutputProps = templates.getOutputProperties();

        // Create a ContentHandler to handle parsing of the XML
        TransformerHandler stylesheetHandler = saxFactory.newTransformerHandler(templates);
        // Also set systemId to the stylesheet
        stylesheetHandler.setSystemId(filenameToURL(xslName));

        // Untimed: Set any of our options as Attributes on the transformer
        TraxWrapperUtils.setAttributes(stylesheetHandler.getTransformer(), newProcessorOpts);

        // Apply any parameters needed
        applyParameters(stylesheetHandler.getTransformer());

        // Use a new XMLReader to parse the XML document
        XMLReader xmlReader = getJAXPXMLReader();
        xmlReader.setContentHandler(stylesheetHandler);

        // Set the ContentHandler to also function as LexicalHandler,
        // includes "lexical" events (e.g., comments and CDATA).
        xmlReader.setProperty(
                "http://xml.org/sax/properties/lexical-handler",
                stylesheetHandler);

        // Also attempt to set as a DeclHandler, which Xalan-J
        //  supports even though it is not required by JAXP
        // Ignore exceptions for other processors since this
        //  is not a required setting
        try {
            xmlReader.setProperty(
                    "http://xml.org/sax/properties/declaration-handler",
                    stylesheetHandler);
        } catch (SAXException se) { /* no-op - ignore */ }

        // added by sb. Tie together DTD and other handling
        xmlReader.setDTDHandler(stylesheetHandler);
        try {
            xmlReader.setFeature(
                    "http://xml.org/sax/features/namespace-prefixes",
                    true);
        } catch (SAXException se) { /* no-op - ignore */ }
        try {
            xmlReader.setFeature(
                    "http://apache.org/xml/features/validation/dynamic",
                    true);
        } catch (SAXException se) { /* no-op - ignore */ }

        // Create a 'pipe'-like identity transformer, so we can
        //  easily get our results serialized to disk
        TransformerHandler serializingHandler = saxFactory.newTransformerHandler();
        // Set the stylesheet's output properties into the output
        //  via it's Transformer
        serializingHandler.getTransformer().setOutputProperties(xslOutputProps);

        // Create StreamResult to byte stream in memory
        ByteArrayOutputStream outBytes = new ByteArrayOutputStream();
        StreamResult byteResult = new StreamResult(outBytes);
        serializingHandler.setResult(byteResult);

        // Create a SAXResult dumping into our 'pipe' serializer
        //  and tie in lexical handling (is any other handling needed?)
        SAXResult saxResult = new SAXResult(serializingHandler);
        saxResult.setLexicalHandler(serializingHandler);

        // Set the original stylesheet to dump into our result
        stylesheetHandler.setResult(saxResult);

        // Parse the XML input document and do transform
        xmlReader.parse(filenameToURL(xmlName));

        // writeResults from the byte array
        byte[] writeBytes = outBytes.toByteArray(); // Should this be timed too or not?
        try (FileOutputStream writeStream = new FileOutputStream(resultName)) {
            writeStream.write(writeBytes);
        }
    }

    /**
     * Pre-build/pre-compile a stylesheet.
     *
     * Although the actual mechanics are implementation-dependent, most
     * processors have some method of pre-setting up the data needed by the
     * stylesheet itself for later use in transforms. In
     * TrAX/javax.xml.transform, this equates to creating a Templates object.
     *
     * Sets isStylesheetReady() to true if it succeeds. Users can then call
     * transformWithStylesheet(xmlName, resultName) to actually perform a
     * transformation with this pre-built stylesheet.
     *
     * @param xslName local path\filename of XSL stylesheet to use
     *
     * @throws Exception any underlying exceptions from the wrapped processor
     * are simply allowed to propagate; throws a RuntimeException if any other
     * problems prevent us from actually completing the operation
     *
     * @see #transformWithStylesheet(String xmlName, String resultName)
     */
    @Override
    public void buildStylesheet(String xslName) throws Exception {
        preventFootShooting();

        // Create a ContentHandler to handle parsing of the xsl
        TemplatesHandler templatesHandler = saxFactory.newTemplatesHandler();

        // Create an XMLReader and set its ContentHandler.
        XMLReader xslReader = getJAXPXMLReader();
        xslReader.setContentHandler(templatesHandler);

        // read/build Templates from StreamSource
        xslReader.parse(filenameToURL(xslName));

        // Also set systemId to the stylesheet
        templatesHandler.setSystemId(filenameToURL(xslName));

        // Get the Templates object from the ContentHandler.
        builtTemplates = templatesHandler.getTemplates();
        m_stylesheetReady = true;
    }

    /**
     * Transform supplied xmlName file with a pre-built/pre-compiled stylesheet
     * into a resultName file.
     *
     * User must have called buildStylesheet(xslName) beforehand, obviously.
     * Names are assumed to be local path\filename references, and will be
     * converted to URLs as needed.
     *
     * @param xmlName local path\filename of XML file to transform
     * @param resultName local path\filename to put result in
     *
     * @throws Exception any underlying exceptions from the wrappered processor
     * are simply allowed to propagate; throws a RuntimeException if any other
     * problems prevent us from actually completing the operation; throws an
     * IllegalStateException if isStylesheetReady() == false.
     *
     * @see #buildStylesheet(String xslName)
     */
    @Override
    public void transformWithStylesheet(String xmlName, String resultName)
            throws Exception {
        if (!isStylesheetReady()) {
            throw new IllegalStateException("transformWithStylesheet() when isStylesheetReady() == false");
        }
        preventFootShooting();

        // Get the outputProperties from the stylesheet, so
        //  we can later use them for the serialization
        Properties xslOutputProps = builtTemplates.getOutputProperties();

        // Create a ContentHandler to handle parsing of the XML
        TransformerHandler stylesheetHandler = saxFactory.newTransformerHandler(builtTemplates);

        // Untimed: Set any of our options as Attributes on the transformer
        TraxWrapperUtils.setAttributes(stylesheetHandler.getTransformer(), newProcessorOpts);

        // Apply any parameters needed
        applyParameters(stylesheetHandler.getTransformer());

        // Use a new XMLReader to parse the XML document
        XMLReader xmlReader = getJAXPXMLReader();
        xmlReader.setContentHandler(stylesheetHandler);

        // Set the ContentHandler to also function as LexicalHandler,
        // includes "lexical" events (e.g., comments and CDATA).
        xmlReader.setProperty(
                "http://xml.org/sax/properties/lexical-handler",
                stylesheetHandler);
        xmlReader.setProperty(
                "http://xml.org/sax/properties/declaration-handler",
                stylesheetHandler);

        // added by sb. Tie together DTD and other handling
        xmlReader.setDTDHandler(stylesheetHandler);
        try {
            xmlReader.setFeature(
                    "http://xml.org/sax/features/namespace-prefixes",
                    true);
        } catch (SAXException se) { /* no-op - ignore */ }
        try {
            xmlReader.setFeature(
                    "http://apache.org/xml/features/validation/dynamic",
                    true);
        } catch (SAXException se) { /* no-op - ignore */ }

        // Create a 'pipe'-like identity transformer, so we can
        //  easily get our results serialized to disk
        TransformerHandler serializingHandler = saxFactory.newTransformerHandler();
        // Set the stylesheet's output properties into the output
        //  via it's Transformer
        serializingHandler.getTransformer().setOutputProperties(xslOutputProps);

        // Create StreamResult to byte stream in memory
        ByteArrayOutputStream outBytes = new ByteArrayOutputStream();
        StreamResult byteResult = new StreamResult(outBytes);
        serializingHandler.setResult(byteResult);

        // Create a SAXResult dumping into our 'pipe' serializer
        //  and tie in lexical handling (is any other handling needed?)
        SAXResult saxResult = new SAXResult(serializingHandler);
        saxResult.setLexicalHandler(serializingHandler);

        // Set the original stylesheet to dump into our result
        stylesheetHandler.setResult(saxResult);

        // Timed: Parse the XML input document and do transform
        xmlReader.parse(filenameToURL(xmlName));

        // Timed: writeResults from the byte array
        byte[] writeBytes = outBytes.toByteArray(); // Should this be timed too or not?
        try (FileOutputStream writeStream = new FileOutputStream(resultName)) {
            writeStream.write(writeBytes);
        }
    }

    /**
     * Transform supplied xmlName file with a stylesheet found in an
     * xml-stylesheet PI into a resultName file.
     *
     * Names are assumed to be local path\filename references, and will be
     * converted to URLs as needed. Implementations will use whatever facilities
     * exist in their wrappered processor to fetch and build the stylesheet to
     * use for the transform.
     *
     * @param xmlName local path\filename of XML file to transform
     * @param resultName local path\filename to put result in
     *
     * @throws Exception any underlying exceptions from the wrappered processor
     * are simply allowed to propagate; throws a RuntimeException if any other
     * problems prevent us from actually completing the operation
     */
    @Override
    public void transformEmbedded(String xmlName, String resultName)
            throws Exception {
        throw new RuntimeException("TraxSAXWrapper.transformEmbedded not implemented yet!");
    }

    /**
     * Reset our parameters and wrapper state, and optionally force creation of
     * a new underlying processor implementation.
     *
     * This always clears our built stylesheet and any parameters that have been
     * set. If newProcessor is true, also forces a re-creation of our underlying
     * processor as if by calling newProcessor().
     *
     * @param newProcessor if we should reset our underlying processor
     * implementation as well
     */
    @Override
    public void reset(boolean newProcessor) {
        super.reset(newProcessor); // clears indent and parameters
        m_stylesheetReady = false;
        builtTemplates = null;
        if (newProcessor) {
            try {
                newProcessor(newProcessorOpts);
            } catch (TransformerConfigurationException ignore) {}
        }
    }

    /**
     * Apply a single parameter to a Transformer.
     *
     * Overridden to take a Transformer and call setParameter().
     *
     * @param transformer a Transformer object.
     * @param namespace for the parameter, may be null
     * @param name for the parameter, should not be null
     * @param value for the parameter, may be null
     */
    @Override
    protected void applyParameter(Transformer transformer, String namespace,
            String name, String value) {
        try {
            // Munge the namespace into the name per
            //  javax.xml.transform.Transformer.setParameter()
            if (null != namespace) {
                name = "{" + namespace + "}" + name;
            }
            transformer.setParameter(name, value);
        } catch (Exception e) {
            throw new IllegalArgumentException("applyParameter threw: " + e.toString());
        }
    }

    /**
     * Ensure newProcessor has been called when needed.
     *
     * Prevent users from shooting themselves in the foot by calling a
     * transform* API before newProcessor().
     *
     * (Sorry, I couldn't resist)
     * @throws java.lang.Exception
     */
    public void preventFootShooting() throws Exception {
        if (null == factory) {
            newProcessor(newProcessorOpts);
        }
    }

    /**
     * Worker method to get an XMLReader.
     *
     * Not the most efficient of methods, but makes the code simpler.
     *
     * @return a new XMLReader for use, with setNamespaceAware(true)
     * @throws java.lang.Exception
     */
    protected XMLReader getJAXPXMLReader() throws Exception {
        // Be sure to use the JAXP methods only!
        SAXParserFactory sfactory = SAXParserFactory.newInstance();
        sfactory.setNamespaceAware(true);
        return sfactory.newSAXParser().getXMLReader();
    }
}