// SAXDriver.java: The SAX driver for AElfred.
// NO WARRANTY! See README, and copyright below.
// $Id$
package com.microstar.xml.driver;

import java.io.IOException;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Locale;
import java.util.Stack;
import java.util.Vector;

import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.DTDHandler;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;

import com.microstar.xml.XmlHandler;
import com.microstar.xml.XmlParser;

/**
 * A SAX driver for Microstar's Ælfred XML parser.
 *
 * <p>This driver acts as a front-end for &AElig;lfred, and
 * translates &AElig;lfred's events into SAX events.  It
 * implements the SAX parser interface, and you can use it without
 * directly calling &AElig;lfred at all:</p>
 *
 * <pre>
 * org.xml.sax.Parser parser = new com.microstar.xml.SAXDriver();
 * </pre>
 *
 * <p>When you are using SAX, you do not need to use the
 * <code>XmlParser</code> or <code>XmlHandler</code> classes at
 * all: this class is your entry point.</p>
 *
 * <p>This driver is based on the 1.0gamma version of SAX,
 * available from http://www.megginson.com/SAX/</p>
 *
 * @author Copyright (c) 1998 by Microstar Software Ltd.
 * @author written by David Megginson &lt;dmeggins@microstar.com&gt;
 * @version 1.1
 * @since Ptolemy II 0.2
 * @see XmlParser
 */
public class SAXDriver implements XmlHandler, Locator, Attributes, XMLReader //implements XmlHandler, Locator, AttributeList, Parser
{
    //
    // Variables.
    //
    //private HandlerBase base = new HandlerBase();
    private DefaultHandler base = new DefaultHandler();

    private XmlParser parser;

    private boolean seenDTDEvents = false;

    // Encapsulate the default behaviour
    // from HandlerBase
    private EntityResolver entityResolver = base;

    private DTDHandler dtdHandler = base;

    private ContentHandler documentHandler = base;

    private ErrorHandler errorHandler = base;

    private String elementName = null;

    private Stack entityStack = new Stack();

    private Vector attributeNames = new Vector();

    private Vector attributeValues = new Vector();

    private Hashtable properties = new Hashtable();

    private Hashtable features = new Hashtable();

    //
    // Constructor.
    //
    public SAXDriver() {
    }

    //
    // Implementation of org.xml.sax.Parser.
    //

    /**
     * Set the locale.
     * @param locale The Locale
     * @exception SAXException Always thrown in this base class.
     */
    public void setLocale(Locale locale) throws SAXException {
        throw new SAXException(
                "AElfred driver does not yet have locale support.");
    }

    /**
     * Set the entity resolver for this parser.
     * @param resolver The object to receive resolve entity events.
     */
    @Override
    public void setEntityResolver(EntityResolver resolver) {
        this.entityResolver = resolver;
    }

    /**
     * Set the DTD handler for this parser.
     * @param handler The object to receive DTD events.
     */
    @Override
    public void setDTDHandler(DTDHandler handler) {
        this.dtdHandler = handler;
    }

    /**
     * Set the document handler for this parser.
     * @param handler The object to receive document events.
     */
    public void setDocumentHandler(ContentHandler handler) {
        this.documentHandler = handler;
    }

    /**
     * Set the error handler for this parser.
     * @param handler The object to receive error events.
     */
    @Override
    public void setErrorHandler(ErrorHandler handler) {
        this.errorHandler = handler;
    }

    /**
     * Parse a document.
     * <p>If you want anything useful to happen, you should set
     * at least one type of handler.
     * @param source The XML input source.
     * @see #setEntityResolver
     * @see #setDTDHandler
     * @see #setDocumentHandler
     * @see #setErrorHandler
     * @exception SAXException The handlers may throw any exception.
     */
    @Override
    public void parse(InputSource source) throws SAXException {
        parser = new XmlParser();
        parser.setHandler(this);

        try {
            if (source.getCharacterStream() != null) {
                parser.parse(source.getSystemId(), source.getPublicId(),
                        source.getCharacterStream());
            } else if (source.getByteStream() != null) {
                parser.parse(source.getSystemId(), source.getPublicId(),
                        source.getByteStream(), source.getEncoding());
            } else {
                parser.parse(source.getSystemId(), source.getPublicId(),
                        source.getEncoding());
            }
        } catch (SAXException e) {
            throw e;
        } catch (Exception e) {
            throw new SAXException(e);
        } finally {
            try {
                closeStreams(source);
            } catch (Exception e) {
                throw new SAXException(e);
            }

            ;
        }

        try {
            closeStreams(source);
        } catch (IOException e) {
            throw new SAXException(e);
        }
    }

    /**
     * Parse an XML document from a system identifier (URI).
     */
    @Override
    public void parse(String systemId) throws SAXException {
        parse(new InputSource(systemId));
    }

    /**
     * Close any streams provided.
     */
    private void closeStreams(InputSource source) throws IOException {
        if (source.getCharacterStream() != null) {
            source.getCharacterStream().close();
        }

        if (source.getByteStream() != null) {
            source.getByteStream().close();
        }
    }

    //
    // Implementation of com.microstar.xml.XmlHandler.
    // This is where the driver receives AElfred events and translates
    // them into SAX events.
    //

    /**
     * Implement com.microstar.xml.XmlHandler#startDocument.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#startDocument
     * @exception SAXException May throw any exception.
     */
    @Override
    public void startDocument() throws SAXException {
        documentHandler.setDocumentLocator(this);
        documentHandler.startDocument();
        attributeNames.removeAllElements();
        attributeValues.removeAllElements();
    }

    /**
     * Implement com.microstar.xml.XmlHandler#endDocument.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#endDocument
     * @exception SAXException May throw any exception.
     */
    @Override
    public void endDocument() throws SAXException {
        documentHandler.endDocument();
    }

    /**
     * Implement com.microstar.xml.XmlHandler.resolveSystemId
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#resolveEntity
     * @exception SAXException May throw any exception.
     */
    @Override
    public Object resolveEntity(String publicId, String systemId)
            throws SAXException, IOException {
        InputSource source = entityResolver.resolveEntity(publicId, systemId);

        if (source == null) {
            return null;
        } else if (source.getCharacterStream() != null) {
            return source.getCharacterStream();
        } else if (source.getByteStream() != null) {
            return source.getByteStream();
        } else {
            return source.getSystemId();
        }

        // FIXME: no way to tell AElfred
        // about a new public id.
    }

    /**
     * Implement com.microstar.xml.XmlHandler#startExternalEntity.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#startExternalEntity
     * @exception SAXException May throw any exception.
     */
    @Override
    public void startExternalEntity(String systemId) throws SAXException {
        entityStack.push(systemId);
    }

    /**
     * Implement com.microstar.xml.XmlHandler#endExternalEntity.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#endExternalEntity
     * @exception SAXException May throw any exception.
     */
    @Override
    public void endExternalEntity(String systemId) throws SAXException {
        entityStack.pop();
    }

    /**
     * Implement com.microstar.xml.XmlHandler#doctypeDecl.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#doctypeDecl
     * @exception SAXException May throw any exception.
     */
    @Override
    public void doctypeDecl(String name, String publicId, String systemId)
            throws SAXException {
        // no op
    }

    /**
     * Implement com.microstar.xml.XmlHandler#attribute.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#attribute
     * @exception SAXException May throw any exception.
     */
    @Override
    public void attribute(String aname, String value, boolean isSpecified)
            throws SAXException {
        if (value != null) {
            attributeNames.addElement(aname);
            attributeValues.addElement(value);
        }
    }

    /**
     * Implement com.microstar.xml.XmlHandler#startElement.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#startElement
     * @exception SAXException May throw any exception.
     */
    @Override
    public void startElement(String elname) throws SAXException {
        // We should deliver all DTD events
        // before the first startElement event.
        if (!seenDTDEvents) {
            deliverDTDEvents();
            seenDTDEvents = true;
        }

        elementName = elname;

        //documentHandler.startElement(elname, this);
        documentHandler.startElement("", elname, "", this);
        elementName = null;
        attributeNames.removeAllElements();
        attributeValues.removeAllElements();
    }

    /**
     * Implement com.microstar.xml.XmlHandler#endElement.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#endElement
     * @exception SAXException May throw any exception.
     */
    @Override
    public void endElement(String elname) throws SAXException {
        //documentHandler.endElement(elname);
        documentHandler.endElement("", elname, "");
    }

    /**
     * Implement com.microstar.xml.XmlHandler#charData.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#charData
     * @exception SAXException May throw any exception.
     */
    @Override
    public void charData(char[] ch, int start, int length) throws SAXException {
        documentHandler.characters(ch, start, length);
    }

    /**
     * Implement com.microstar.xml.XmlHandler#ignorableWhitespace.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#ignorableWhitespace
     * @exception SAXException May throw any exception.
     */
    @Override
    public void ignorableWhitespace(char[] ch, int start, int length)
            throws SAXException {
        documentHandler.ignorableWhitespace(ch, start, length);
    }

    /**
     * Implement com.microstar.xml.XmlHandler#processingInstruction.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#processingInstruction
     * @exception SAXException May throw any exception.
     */
    @Override
    public void processingInstruction(String target, String data)
            throws SAXException {
        documentHandler.processingInstruction(target, data);
    }

    /**
     * Implement com.microstar.xml.XmlHandler#error.
     * <p>Translate to the SAX interface.
     * <p>Users should never invoke this method directly.
     * @see com.microstar.xml.XmlHandler#error
     * @exception SAXException May throw any exception.
     */
    @Override
    public void error(String message, String url, int line, int column)
            throws SAXException {
        errorHandler.fatalError(
                new SAXParseException(message, null, url, line, column));
    }

    /**
     * Before the first startElement event, deliver all notation
     * and unparsed entity declarations.
     */
    private void deliverDTDEvents() throws SAXException {
        String ename;
        String nname;
        String publicId;
        String systemId;

        Enumeration notationNames = parser.declaredNotations();
        Enumeration entityNames = parser.declaredEntities();

        // First, report all notations.
        while (notationNames.hasMoreElements()) {
            nname = (String) notationNames.nextElement();
            publicId = parser.getNotationPublicId(nname);
            systemId = parser.getNotationSystemId(nname);
            dtdHandler.notationDecl(nname, publicId, systemId);
        }

        // Next, report all unparsed entities.
        while (entityNames.hasMoreElements()) {
            ename = (String) entityNames.nextElement();

            if (parser.getEntityType(ename) == XmlParser.ENTITY_NDATA) {
                publicId = parser.getEntityPublicId(ename);
                systemId = parser.getEntitySystemId(ename);
                nname = parser.getEntityNotationName(ename);
                dtdHandler.unparsedEntityDecl(ename, publicId, systemId, nname);
            }
        }
    }

    //
    // Implementation of org.xml.sax.AttributeList.
    //
    @Override
    public int getLength() {
        return attributeNames.size();
    }

    public String getName(int i) {
        return (String) attributeNames.elementAt(i);
    }

    @Override
    public String getType(int i) {
        switch (parser.getAttributeType(elementName, getName(i))) {
        case XmlParser.ATTRIBUTE_UNDECLARED:
        case XmlParser.ATTRIBUTE_CDATA:
            return "CDATA";

        case XmlParser.ATTRIBUTE_ID:
            return "ID";

        case XmlParser.ATTRIBUTE_IDREF:
            return "IDREF";

        case XmlParser.ATTRIBUTE_IDREFS:
            return "IDREFS";

        case XmlParser.ATTRIBUTE_ENTITY:
            return "ENTITY";

        case XmlParser.ATTRIBUTE_ENTITIES:
            return "ENTITIES";

        case XmlParser.ATTRIBUTE_NMTOKEN:
        case XmlParser.ATTRIBUTE_ENUMERATED:
            return "NMTOKEN";

        case XmlParser.ATTRIBUTE_NMTOKENS:
            return "NMTOKENS";

        case XmlParser.ATTRIBUTE_NOTATION:
            return "NOTATION";
        }

        return null;
    }

    @Override
    public String getValue(int i) {
        return (String) attributeValues.elementAt(i);
    }

    @Override
    public String getType(String name) {
        for (int i = 0; i < getLength(); i++) {
            if (name.equals(getName(i))) {
                return getType(i);
            }
        }

        return null;
    }

    @Override
    public String getValue(String name) {
        for (int i = 0; i < getLength(); i++) {
            if (name.equals(getName(i))) {
                return getValue(i);
            }
        }

        return null;
    }

    //
    // Implementation of org.xml.sax.Locator.
    //
    @Override
    public String getPublicId() {
        return null; // TODO
    }

    @Override
    public String getSystemId() {
        return (String) entityStack.peek();
    }

    @Override
    public int getLineNumber() {
        return parser.getLineNumber();
    }

    @Override
    public int getColumnNumber() {
        return parser.getColumnNumber();
    }

    @Override
    public boolean getFeature(String name) {
        // Not Yet Implemented
        if (features.containsKey(name)) {
            return ((Boolean) features.get(name)).booleanValue();
        }

        return false;
    }

    @Override
    public void setFeature(String name, boolean value) {
        // Not Yet Implemented
        features.put(name, Boolean.valueOf(value));
    }

    @Override
    public Object getProperty(String name) {
        // Not Yet Implemented
        if (properties.containsKey(name)) {
            return properties.get(name);
        }

        return null;
    }

    @Override
    public void setProperty(String name, Object value) {
        // Not Yet Implemented
        properties.put(name, value);
    }

    @Override
    public EntityResolver getEntityResolver() {
        // Not Yet Implemented
        return null;
    }

    @Override
    public DTDHandler getDTDHandler() {
        // Not Yet Implemented
        return null;
    }

    @Override
    public void setContentHandler(ContentHandler handler) {
        this.documentHandler = handler;
    }

    @Override
    public ContentHandler getContentHandler() {
        return this.documentHandler;
    }

    @Override
    public ErrorHandler getErrorHandler() {
        return this.errorHandler;
    }

    @Override
    public String getURI(int index) {
        // Not Yet Implemented
        return "";
    }

    @Override
    public String getLocalName(int index) {
        // Not Yet Implemented
        return "";
    }

    @Override
    public String getQName(int index) {
        // Not Yet Implemented
        return "";
    }

    @Override
    public int getIndex(String uri, String localPart) {
        // Not Yet Implemented
        return -1;
    }

    @Override
    public int getIndex(String qName) {
        // Not Yet Implemented
        return -1;
    }

    @Override
    public String getType(String uri, String localName) {
        return "";
    }

    @Override
    public String getValue(String uri, String localName) {
        return "";
    }
}