/**
 * JWAP - A Java Implementation of the WAP Protocols
 * Copyright (C) 2001-2004 Niko Bender
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

package net.sourceforge.jwap.util.wbxml;

import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import net.sourceforge.jwap.util.TransTable;

import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.DocumentType;
import org.w3c.dom.Element;
import org.w3c.dom.Text;

/**
 * to do's :- string table length is in multiple byte format, currently it is assumed to be single byte
 * index in string table should also be read as multiple byte format
 * character encoding supported is only utf-8,
 * for other encodings the termination character in string table can be different...
 *
 *
 * @author <a href="mailto:suvarna@witscale.com">Suvarna Kadam</a>
 */

public class WBXMLDecoder {
	private static WBXMLDecoder instance;
	private DataInputStream wbxmlStream;
	private Document xmlDocument;
	private String publicId = "UNKNOWN";
	private byte publicIdIndex = -1;
	private String encoding;
	private StringBuffer stringTable;

	private byte parentBitMask = (byte) 0x40;
	// The bit representation 10000000
	private byte attributeBitMask = (byte) 0x80;
	// The bit representation 01000000
	private TokenRepository tokenRepository;
	public static WBXMLDecoder getInstance() {
		if (instance == null)
			instance = new WBXMLDecoder();
		return instance;
	}

	private WBXMLDecoder() {
		initialize();
	}

	private void initialize() {

	}

	public Document decode(InputStream wbxmlStream) {
		this.wbxmlStream = new DataInputStream(wbxmlStream);
		try {
			xmlDocument =
				DocumentBuilderFactory
					.newInstance()
					.newDocumentBuilder()
					.newDocument();
			decodeProlog();
			decodeBody();
		} catch (Exception exp) {
			//exp.printStackTrace();
		}
		return xmlDocument;

	}


        public Document decodeFowChk(InputStream wbxmlStream) {
                this.wbxmlStream = new DataInputStream(wbxmlStream);
                try {
                        xmlDocument =
                                DocumentBuilderFactory
                                        .newInstance()
                                        .newDocumentBuilder()
                                        .newDocument();
                        decodeProlog();
                        decodeBody();
                } catch (Exception exp) {
                        //exp.printStackTrace();
                }
                return xmlDocument;

        }


	/**
	 *  currently encoding cannot be specifies as DOM does not have any API to access the XML declaration.
	 * by default utf-16 is used.. If encoding is to be used ...
	 * xmlDocument.getImplementation().String piData = "version=\"1.0\" encoding=\"" + encoding + "\"";
	 * ProcessingInstruction xmlDeclaration = xmlDocument.createProcessingInstruction("xml", piData);
	 * xmlDocument.insertBefore(xmlDeclaration, xmlDocument.getDocumentElement());
	 **/

	private void decodeProlog(){
                try {
                  byte version = wbxmlStream.readByte();


		readPublicID();
		byte charset = wbxmlStream.readByte(); // to do for mutiple byte
		encoding =  TransTable.getTable("charsets").code2str(charset);
		byte strtblSize = wbxmlStream.readByte();
		// TODO for multi-byte and negative size
		stringTable = new StringBuffer(strtblSize);
		for (int i = 0; i < strtblSize; i++)
			stringTable.append((char) wbxmlStream.readByte());
		if (publicIdIndex != -1)
			readPublicIDFromStringTable();
		// Now initialze the token repository as per the public identifier specified
		String publicIDInHex =
			PublicIdentifiers.getInstance().getPublicIdentifierValueHex(
				publicId);
		tokenRepository = TokenRepository.getInstance(publicIDInHex);
                }
                catch (IOException ex) {
                }
	}

	private void readPublicIDFromStringTable() {
		char c = 0x0;
		int endIndex =
			stringTable.toString().indexOf(new String(new char[] { c }), publicIdIndex);
		if (endIndex == -1)
			publicId = stringTable.substring(publicIdIndex);
		else
			publicId = stringTable.substring(publicIdIndex, endIndex);

	}

	private void readPublicID(){
		byte[] multipleBytes = new byte[4];
                byte nextByte = (byte) 0;
                try {
                  nextByte = wbxmlStream.readByte();

                  if (nextByte == 0) {
                    // public id is encoded as string in form:-  0 indexInstringtable
                    publicIdIndex = wbxmlStream.readByte();

                  }
                  else { // public id is encoded in multi-byte integer format(mb_u_int32)
                    int i = 0;
                    StringBuffer strBuf = new StringBuffer();
                    while ( (nextByte & 0x80) == 0x80) { //msb IS 1
                      String str = Integer.toBinaryString(nextByte & 0x7F);
                      if (str.length() < 7) {
                        int zerosToPumpIn = 7 - str.length();
                        for (int j = 0; j < zerosToPumpIn; j++)
                          strBuf.append('0');

                      }
                      strBuf.append(str);
                      nextByte = wbxmlStream.readByte();
                    }
                    String str = Integer.toBinaryString(nextByte & 0x7F);
                    if (str.length() < 7) {
                      int zerosToPumpIn = 7 - str.length();
                      for (int j = 0; j < zerosToPumpIn; j++)
                        strBuf.append('0');

                    }
                    strBuf.append(str);
                    int publicIdValue =
                        Integer.valueOf(strBuf.toString(), 2).intValue();
                    publicId =
                        PublicIdentifiers.getInstance().getPublicIdentifier(
                            publicIdValue);
                  }
                }

             catch (IOException ex) {
             }

	}

	private void decodeBody(){
		writeRootElement();
	}

	private void writeRootElement(){
                byte maskedTokenValue = (byte) 0;
                try {
                  maskedTokenValue = wbxmlStream.readByte();
                }
                catch (IOException ex) {
                }
		byte actualTokenValue = getTokenValue(maskedTokenValue);
		String rootElementName = tokenRepository.getTagName(actualTokenValue);
		try {
			DocumentBuilder builder =
				DocumentBuilderFactory.newInstance().newDocumentBuilder();
			String systemId =
				PublicIdentifiers.getInstance().getSystemIdentifier(publicId);
			DocumentType docType =
				builder.getDOMImplementation().createDocumentType(
					rootElementName,
					publicId,
					systemId);
			xmlDocument =
				builder.getDOMImplementation().createDocument(
					"",
					rootElementName,
					docType);
			if (hasAttributes(maskedTokenValue))
				setAttributes(xmlDocument.getDocumentElement());
			if (hasContent(maskedTokenValue))
				writeChildElement(xmlDocument.getDocumentElement());

		} catch (Exception exp) {
			//exp.printStackTrace();
		}

	}

	private void writeChildElement(Element parent) throws IOException {
		byte maskedTokenValue = wbxmlStream.readByte();
		while (maskedTokenValue != 01) { // END (of parent element)
			byte actualTokenValue = getTokenValue(maskedTokenValue);
			if (isInlineStrToken(maskedTokenValue)) // element has text content
				writeContentAsInlineStr(parent);
			else {
				if (isEntityToken(actualTokenValue)) // element has entity
					writeEntityContent(parent);
				else if (maskedTokenValue == GlobalTokens.OPAQUE)
					// element contains opaque data
					writeOpaqueContent(parent);
				else if (isStringTableReferenceToken(maskedTokenValue)) {