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/*
 * 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 Oliver Burn
 * @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 XMLFileHandler 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;
    }
}