/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999-2003 The Apache Software Foundation.  
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xerces" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 2003, International
 * Business Machines, Inc., http://www.apache.org.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package com.sun.org.apache.xerces.internal.impl;

import java.io.EOFException;
import java.io.IOException;

import com.sun.org.apache.xerces.internal.impl.msg.XMLMessageFormatter;
import com.sun.org.apache.xerces.internal.util.SymbolTable;
import com.sun.org.apache.xerces.internal.xni.XMLString;
import com.sun.org.apache.xerces.internal.xni.parser.XMLComponentManager;
import com.sun.org.apache.xerces.internal.xni.parser.XMLConfigurationException;
import com.sun.org.apache.xerces.internal.xni.parser.XMLInputSource;

/**
 * This class scans the version of the document to determine
 * which scanner to use: XML 1.1 or XML 1.0.
 * The version is scanned using XML 1.1. scanner.  
 * 
 * @author Neil Graham, IBM 
 * @author Elena Litani, IBM
 * @version $Id: XMLVersionDetector.java,v 1.12 2004/02/27 20:36:07 mrglavas Exp $
 */

public class XMLVersionDetector {

    //
    // Constants
    //

    private final static char[] XML11_VERSION = new char[]{'1', '.', '1'};


    // property identifiers

    /** Property identifier: symbol table. */
    protected static final String SYMBOL_TABLE = 
        Constants.XERCES_PROPERTY_PREFIX + Constants.SYMBOL_TABLE_PROPERTY;

    /** Property identifier: error reporter. */
    protected static final String ERROR_REPORTER = 
        Constants.XERCES_PROPERTY_PREFIX + Constants.ERROR_REPORTER_PROPERTY;

    /** Property identifier: entity manager. */
    protected static final String ENTITY_MANAGER = 
        Constants.XERCES_PROPERTY_PREFIX + Constants.ENTITY_MANAGER_PROPERTY;

    //
    // Data
    //

    /** Symbol: "version". */
    protected final static String fVersionSymbol = "version".intern();

    // symbol:  [xml]:
    protected static final String fXMLSymbol = "[xml]".intern();

    /** Symbol table. */
    protected SymbolTable fSymbolTable;

    /** Error reporter. */
    protected XMLErrorReporter fErrorReporter;

    /** Entity manager. */
    protected XMLEntityManager fEntityManager;

    protected String fEncoding = null;

    private XMLString fVersionNum = new XMLString();

    private final char [] fExpectedVersionString = {'<', '?', 'x', 'm', 'l', ' ', 'v', 'e', 'r', 's', 
                    'i', 'o', 'n', '=', ' ', ' ', ' ', ' ', ' '};

    /**
     * 
     * 
     * @param componentManager The component manager.
     *
     * @throws SAXException Throws exception if required features and
     *                      properties cannot be found.
     */
    public void reset(XMLComponentManager componentManager)
        throws XMLConfigurationException {

        // Xerces properties
        fSymbolTable = (SymbolTable)componentManager.getProperty(SYMBOL_TABLE);
        fErrorReporter = (XMLErrorReporter)componentManager.getProperty(ERROR_REPORTER);
        fEntityManager = (XMLEntityManager)componentManager.getProperty(ENTITY_MANAGER);
        for(int i=14; i<fExpectedVersionString.length; i++ )
            fExpectedVersionString[i] = ' ';
    } // reset(XMLComponentManager)

    /**
     * Reset the reference to the appropriate scanner given the version of the
     * document and start document scanning.
     * @param scanner - the scanner to use
     * @param version - the version of the document (XML 1.1 or XML 1.0).
     */
    public void startDocumentParsing(XMLEntityHandler scanner, short version){

        if (version == Constants.XML_VERSION_1_0){
            fEntityManager.setScannerVersion(Constants.XML_VERSION_1_0);
        }
        else {
            fEntityManager.setScannerVersion(Constants.XML_VERSION_1_1);
        }
        // Make sure the locator used by the error reporter is the current entity scanner.
        fErrorReporter.setDocumentLocator(fEntityManager.getEntityScanner());
        
        // Note: above we reset fEntityScanner in the entity manager, thus in startEntity
        // in each scanner fEntityScanner field must be reset to reflect the change.
        // 
        fEntityManager.setEntityHandler(scanner);
        
        scanner.startEntity(fXMLSymbol, fEntityManager.getCurrentResourceIdentifier(), fEncoding, null);        
    }


    /**
     * This methods scans the XML declaration to find out the version 
     * (and provisional encoding)  of the document.
     * The scanning is doing using XML 1.1 scanner.
     * @param inputSource
     * @return short - Constants.XML_VERSION_1_1 if document version 1.1, 
     *                  otherwise Constants.XML_VERSION_1_0 
     * @throws IOException
     */
    public short determineDocVersion(XMLInputSource inputSource) throws IOException {
        fEncoding = fEntityManager.setupCurrentEntity(fXMLSymbol, inputSource, false, true);

        // Must use XML 1.0 scanner to handle whitespace correctly
        // in the XML declaration.
        fEntityManager.setScannerVersion(Constants.XML_VERSION_1_0);
        XMLEntityScanner scanner = fEntityManager.getEntityScanner();
        try {
            if (!scanner.skipString("<?xml")) {
                // definitely not a well-formed 1.1 doc!
                return Constants.XML_VERSION_1_0;
            }
            if (!scanner.skipDeclSpaces()) {
                fixupCurrentEntity(fEntityManager, fExpectedVersionString, 5);
                return Constants.XML_VERSION_1_0;
            }
            if (!scanner.skipString("version")) {
                fixupCurrentEntity(fEntityManager, fExpectedVersionString, 6);
                return Constants.XML_VERSION_1_0;
            }
            scanner.skipDeclSpaces();
            // Check if the next character is '='. If it is then consume it.
            if (scanner.peekChar() != '=') {
                fixupCurrentEntity(fEntityManager, fExpectedVersionString, 13);
                return Constants.XML_VERSION_1_0;
            }
            scanner.scanChar();
            scanner.skipDeclSpaces();
            int quoteChar = scanner.scanChar();
            fExpectedVersionString[14] = (char) quoteChar;
            for (int versionPos = 0; versionPos < XML11_VERSION.length; versionPos++) {
                fExpectedVersionString[15 + versionPos] = (char) scanner.scanChar();
            }
            // REVISIT:  should we check whether this equals quoteChar? 
            fExpectedVersionString[18] = (char) scanner.scanChar();
            fixupCurrentEntity(fEntityManager, fExpectedVersionString, 19);
            int matched = 0;
            for (; matched < XML11_VERSION.length; matched++) {
                if (fExpectedVersionString[15 + matched] != XML11_VERSION[matched])
                    break;
            }
            if (matched == XML11_VERSION.length)
                return Constants.XML_VERSION_1_1;
            return Constants.XML_VERSION_1_0;
            // premature end of file
        }
        catch (EOFException e) {
            fErrorReporter.reportError(
                XMLMessageFormatter.XML_DOMAIN,
                "PrematureEOF",
                null,
                XMLErrorReporter.SEVERITY_FATAL_ERROR);
            return Constants.XML_VERSION_1_0;
			
        }

    }

    // This method prepends "length" chars from the char array,
    // from offset 0, to the manager's fCurrentEntity.ch.
    private void fixupCurrentEntity(XMLEntityManager manager, 
                char [] scannedChars, int length) {
        XMLEntityManager.ScannedEntity currentEntity = manager.getCurrentEntity();
        if(currentEntity.count-currentEntity.position+length > currentEntity.ch.length) {
            //resize array; this case is hard to imagine...
            char[] tempCh = currentEntity.ch;
            currentEntity.ch = new char[length+currentEntity.count-currentEntity.position+1];
            System.arraycopy(tempCh, 0, currentEntity.ch, 0, tempCh.length);
        }
        if(currentEntity.position < length) {
            // have to move sensitive stuff out of the way...
            System.arraycopy(currentEntity.ch, currentEntity.position, currentEntity.ch, length, currentEntity.count-currentEntity.position);
            currentEntity.count += length-currentEntity.position;
        } else {
            // have to reintroduce some whitespace so this parses:
            for(int i=length; i<currentEntity.position; i++) 
                currentEntity.ch[i]=' ';
        }
        // prepend contents...
        System.arraycopy(scannedChars, 0, currentEntity.ch, 0, length);
        currentEntity.position = 0;
        currentEntity.columnNumber = currentEntity.lineNumber = 1;
    }

} // class XMLVersionDetector