/*
 * 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.log4j.chainsaw;

import java.util.StringTokenizer;
import org.apache.log4j.Level;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * A content handler for document containing Log4J events logged using the
 * XMLLayout class. It will create events and add them to a supplied model.
 *
 * @author <a href="mailto:oliver@puppycrawl.com">Oliver Burn</a>
 * @version 1.0
 */
class XMLFileHandler extends DefaultHandler {
    /** represents the event tag **/
    private static final String TAG_EVENT = "log4j:event";
    /** represents the message tag **/
    private static final String TAG_MESSAGE = "log4j:message";
    /** represents the ndc tag **/
    private static final String TAG_NDC = "log4j:NDC";
    /** represents the throwable tag **/
    private static final String TAG_THROWABLE = "log4j:throwable";
    /** represents the location info tag **/
    private static final String TAG_LOCATION_INFO = "log4j:locationInfo";

    /** where to put the events **/
    private final MyTableModel mModel;
    /** the number of events in the document **/
    private int mNumEvents;

    /** the time of the event **/
    private long mTimeStamp;
    /** the priority (level) of the event **/
    private Level mLevel;
    /** the category of the event **/
    private String mCategoryName;
    /** the NDC for the event **/
    private String mNDC;
    /** the thread for the event **/
    private String mThreadName;
    /** the msg for the event **/
    private String mMessage;
    /** the throwable details the event **/
    private String[] mThrowableStrRep;
    /** the location details for the event **/
    private String mLocationDetails;
    /** buffer for collecting text **/
    private final StringBuffer mBuf = new StringBuffer();

    /**
     * Creates a new <code>XMLFileHandler</code> instance.
     *
     * @param aModel where to add the events
     */
    XMLFileHandler(MyTableModel aModel) {
	mModel = aModel;
    }

    /** @see DefaultHandler **/
    public void startDocument() throws SAXException {
	mNumEvents = 0;
    }

    /** @see DefaultHandler **/
    public void characters(char[] aChars, int aStart, int aLength) {
	mBuf.append(String.valueOf(aChars, aStart, aLength));
    }

    /** @see DefaultHandler **/
    public void endElement(String aNamespaceURI, String aLocalName, String aQName) {
	if (TAG_EVENT.equals(aQName)) {
	    addEvent();
	    resetData();
	} else if (TAG_NDC.equals(aQName)) {
	    mNDC = mBuf.toString();
	} else if (TAG_MESSAGE.equals(aQName)) {
	    mMessage = mBuf.toString();
	} else if (TAG_THROWABLE.equals(aQName)) {
	    final StringTokenizer st = new StringTokenizer(mBuf.toString(), "\n\t");
	    mThrowableStrRep = new String[st.countTokens()];
	    if (mThrowableStrRep.length > 0) {
		mThrowableStrRep[0] = st.nextToken();
		for (int i = 1; i < mThrowableStrRep.length; i++) {
		    mThrowableStrRep[i] = "\t" + st.nextToken();
		}
	    }
	}
    }

    /** @see DefaultHandler **/
    public void startElement(String aNamespaceURI, String aLocalName, String aQName, Attributes aAtts) {
	mBuf.setLength(0);

	if (TAG_EVENT.equals(aQName)) {
	    mThreadName = aAtts.getValue("thread");
	    mTimeStamp = Long.parseLong(aAtts.getValue("timestamp"));
	    mCategoryName = aAtts.getValue("logger");
	    mLevel = Level.toLevel(aAtts.getValue("level"));
	} else if (TAG_LOCATION_INFO.equals(aQName)) {
	    mLocationDetails = aAtts.getValue("class") + "." + aAtts.getValue("method") + "(" + aAtts.getValue("file")
		    + ":" + aAtts.getValue("line") + ")";
	}
    }

    /** @return the number of events in the document **/
    int getNumEvents() {
	return mNumEvents;
    }

    ////////////////////////////////////////////////////////////////////////////
    // Private methods
    ////////////////////////////////////////////////////////////////////////////

    /** Add an event to the model **/
    private void addEvent() {
	mModel.addEvent(new EventDetails(mTimeStamp, mLevel, mCategoryName, mNDC, mThreadName, mMessage,
		mThrowableStrRep, mLocationDetails));
	mNumEvents++;
    }

    /** Reset the data for an event **/
    private void resetData() {
	mTimeStamp = 0;
	mLevel = null;
	mCategoryName = null;
	mNDC = null;
	mThreadName = null;
	mMessage = null;
	mThrowableStrRep = null;
	mLocationDetails = null;
    }
}
