/*
 * Copyright (c) 2000, 2017 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package com.sun.messaging.jmq.jmsclient.validation;

import java.io.IOException;
import java.io.StringReader;
import java.util.StringTokenizer;
import java.util.Vector;

import javax.jms.JMSException;
import javax.xml.XMLConstants;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Validator;

import org.xml.sax.SAXException;

import com.sun.messaging.jmq.jmsclient.Debug;
import com.sun.messaging.jmq.jmsclient.ExceptionHandler;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.stream.StreamResult;

/**
 * This class is used to validate if an XML document is valid.
 *
 *
 * @author chiaming
 */
public class XMLValidator {
    /**
     * System property to turn on/off xml schema validation. If set to true, XML content is validated against the schema
     * provided or from the content declaration.
     *
     */
    static public final String IS_Validate = "imq.xml.schema.validate";

    /**
     * System property to set the XSD URI list for this validator
     */
    static public final String XSD_URI_LIST = "imq.xml.schema.uri";

    // urilist
    private Vector urilist = null;

    private String xsdURIList = null;

    private Schema schema = null;

    private Validator validator = null;

    private StreamSource ssarray[] = null;

    private boolean reloadXSDOnFailure = false;

    // default supported schema language
    private String schemaLanguage = XMLConstants.W3C_XML_SCHEMA_NS_URI;

    private SAXParser saxParser = null;

    private EventHandler eventHandler = null;

    private boolean debug = Debug.debug;

    /**
     * This constructor is used to construct an instance to validate XML DTD. When no external schema uri is configured,
     * this is used.
     *
     * @throws javax.jms.JMSException
     */
    protected XMLValidator() throws JMSException {

        try {

            SAXParserFactory saxFactory = SAXParserFactory.newInstance();

            saxFactory.setValidating(true);

            // parser to be used to validate xml DTD
            saxParser = saxFactory.newSAXParser();

            // default handler for the above sax parser
            eventHandler = new EventHandler();

        } catch (Exception ex) {
            JMSException jmse = new com.sun.messaging.jms.JMSException(ex.getMessage());

            jmse.setLinkedException(ex);

            ExceptionHandler.throwJMSException(jmse);
        }
    }

    protected XMLValidator(String xsdURIList) throws JMSException {
        // by default, use XML schema language
        this(XMLConstants.W3C_XML_SCHEMA_NS_URI, xsdURIList);
    }

    /**
     *
     * @param xsdURIList
     */
    protected XMLValidator(String schemaLang, String xsdURIList) throws JMSException {

        try {

            // save the xsd uri list string
            this.xsdURIList = xsdURIList;

            // put uri list string into urilist vector
            if (xsdURIList == null) {
                throw new NullPointerException("XSD URI List can not be null");
            } else {
                this.urilist = new Vector();
                // this.xsdURIList = xsdURIList;
            }

            StringTokenizer tokens = new StringTokenizer(xsdURIList, " ");

            while (tokens.hasMoreElements()) {
                String uri = tokens.nextToken();

                this.urilist.add(uri);
            }

            if (schemaLang != null) {
                this.setSchemaLanguage(schemaLang);
            }

            // this.setXSDURI(xsdURIList);

            this.initSchema();

        } catch (Exception ex) {

            JMSException jmse = new com.sun.messaging.jms.JMSException(ex.getMessage());

            jmse.setLinkedException(ex);

            ExceptionHandler.throwJMSException(jmse);
        }
    }

    /**
     * @param xsdURIList URI list separated by " "
     */
    private synchronized void initStreamSource() {

        int size = urilist.size();
        ssarray = new StreamSource[size];
        for (int i = 0; i < size; i++) {
            String uri = (String) urilist.elementAt(i);
            ssarray[i] = new StreamSource(uri);
        }
    }

    private synchronized void setSchemaLanguage(String schemaLanguage) {
        this.schemaLanguage = schemaLanguage;
    }

    private synchronized void initSchema() throws SAXException {

        // get the stream source array
        this.initStreamSource();

        // create a SchemaFactory capable of understanding
        // the specified schemas
        SchemaFactory factory = SchemaFactory.newInstance(schemaLanguage);
        schema = factory.newSchema(ssarray);

        validator = schema.newValidator();

        ErrorHandler errorHandler = new ErrorHandler();
        validator.setErrorHandler(errorHandler);
    }

    /**
     * validate an XML document.
     *
     * @param xml
     * @throws javax.jms.JMSException
     */
    public synchronized void validate(String xml) throws JMSException {

        try {

            if (validator != null) {

                if (this.reloadXSDOnFailure) {
                    this.reloadXMLSchemaOnFailure(xml);
                } else {
                    this.doValidateXSD(xml);
                }

            } else if (this.saxParser != null) {

                StringReader reader = new StringReader(xml);
                // use SAX input source
                org.xml.sax.InputSource isource = new org.xml.sax.InputSource(reader);

                this.saxParser.parse(isource, this.eventHandler);

                this.saxParser.reset();
                // System.out.println ("DTD validated by internal SAXParser.");
            }

        } catch (Exception ex) {
            JMSException jmse = new com.sun.messaging.jms.JMSException(ex.getMessage());

            jmse.setLinkedException(ex);

            ExceptionHandler.throwJMSException(jmse);
        }

    }

    private synchronized void reloadXMLSchemaOnFailure(String xml) throws SAXException, IOException {

        if (debug) {
            Debug.println("*** In reloadXMLSchemaOnFailure, validating xml ... ");
        }

        try {
            this.doValidateXSD(xml);
        } catch (Exception e) {

            if (debug) {
                Debug.println("*** reloading XSD from " + this.xsdURIList);
            }

            // reload xsd
            this.initSchema();

            if (debug) {
                Debug.println("*** re-validating XML ..." + xml);
            }

            // re-validate
            this.doValidateXSD(xml);
        }
    }

    /**
     * validate xml with validator.
     *
     * @param xml
     * @throws Exception
     */
    private synchronized void doValidateXSD(String xml) throws SAXException, IOException {

        StringReader reader = new StringReader(xml);
        // use SAX input source
        org.xml.sax.InputSource isource = new org.xml.sax.InputSource(reader);
        SAXSource saxSource = new SAXSource(isource);

        validator.validate(saxSource);
    }

    public synchronized void validateURI(String xmluri) throws JMSException {

        try {

            if (validator != null) {

                StreamResult result = new StreamResult(System.out);
                StreamSource source = new StreamSource(xmluri);

                // StreamSource works for JDK 1.6 only.
                validator.validate(source, result);
            } else if (this.saxParser != null) {

                System.out.println("*** use saxParser .... isValidating: " + this.saxParser.isValidating());
                this.saxParser.parse(xmluri, this.eventHandler);
            }

        } catch (Exception ex) {
            JMSException jmse = new com.sun.messaging.jms.JMSException(ex.getMessage());

            jmse.setLinkedException(ex);

            ExceptionHandler.throwJMSException(jmse);
        }

    }

    public String getURIList() {
        return this.xsdURIList;
    }

    public synchronized void setReloadOnFailure(boolean doReload) {
        this.reloadXSDOnFailure = doReload;
    }

    public boolean getReloadOnFailure() {
        return this.reloadXSDOnFailure;
    }

    public static void main(String[] args) throws Exception {

        if (args.length == 2) {
            // System.out.println("Usage: XMLValidator schemaURIList xmlInstanceURI");
            // System.exit(1);

            XMLValidator xmlValidator = new XMLValidator(args[0]);
            xmlValidator.validateURI(args[1]);

            System.out.println("xml is validated: " + args[1]);
        } else {

            XMLValidator xmlValidator = new XMLValidator();
            xmlValidator.validateURI(args[0]);
            System.out.println("xml is validated without schema: " + args[0]);
        }

    }

}
