/*
 * 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.varia;

import org.apache.log4j.Level;
import org.apache.log4j.spi.Filter;
import org.apache.log4j.spi.LoggingEvent;

/**
 * This is a very simple filter based on level matching, which can be used to
 * reject messages with priorities outside a certain range.
 * 
 * <p>
 * The filter admits three options <b>LevelMin</b>, <b>LevelMax</b> and
 * <b>AcceptOnMatch</b>.
 * 
 * <p>
 * If the level of the {@link LoggingEvent} is not between Min and Max
 * (inclusive), then {@link Filter#DENY} is returned.
 * 
 * <p>
 * If the Logging event level is within the specified range, then if
 * <b>AcceptOnMatch</b> is true, {@link Filter#ACCEPT} is returned, and if
 * <b>AcceptOnMatch</b> is false, {@link Filter#NEUTRAL} is returned.
 * 
 * <p>
 * If <code>LevelMin</code>w is not defined, then there is no minimum acceptable
 * level (ie a level is never rejected for being too "low"/unimportant). If
 * <code>LevelMax</code> is not defined, then there is no maximum acceptable
 * level (ie a level is never rejected for beeing too "high"/important).
 * 
 * <p>
 * Refer to the {@link org.apache.log4j.AppenderSkeleton#setThreshold
 * setThreshold} method available to <code>all</code> appenders extending
 * {@link org.apache.log4j.AppenderSkeleton} for a more convenient way to filter
 * out events by level.
 * 
 * @author Simon Kitching
 * @author based on code by Ceki G&uuml;lc&uuml;
 */
public class LevelRangeFilter extends Filter {

    /**
     * Do we return ACCEPT when a match occurs. Default is <code>false</code>, so
     * that later filters get run by default
     */
    boolean acceptOnMatch = false;

    Level levelMin;
    Level levelMax;

    /**
     * Return the decision of this filter.
     */
    public int decide(LoggingEvent event) {
	if (this.levelMin != null) {
	    if (event.getLevel().isGreaterOrEqual(levelMin) == false) {
		// level of event is less than minimum
		return Filter.DENY;
	    }
	}

	if (this.levelMax != null) {
	    if (event.getLevel().toInt() > levelMax.toInt()) {
		// level of event is greater than maximum
		// Alas, there is no Level.isGreater method. and using
		// a combo of isGreaterOrEqual && !Equal seems worse than
		// checking the int values of the level objects..
		return Filter.DENY;
	    }
	}

	if (acceptOnMatch) {
	    // this filter set up to bypass later filters and always return
	    // accept if level in range
	    return Filter.ACCEPT;
	} else {
	    // event is ok for this filter; allow later filters to have a look..
	    return Filter.NEUTRAL;
	}
    }

    /**
     * Get the value of the <code>LevelMax</code> option.
     */
    public Level getLevelMax() {
	return levelMax;
    }

    /**
     * Get the value of the <code>LevelMin</code> option.
     */
    public Level getLevelMin() {
	return levelMin;
    }

    /**
     * Get the value of the <code>AcceptOnMatch</code> option.
     */
    public boolean getAcceptOnMatch() {
	return acceptOnMatch;
    }

    /**
     * Set the <code>LevelMax</code> option.
     */
    public void setLevelMax(Level levelMax) {
	this.levelMax = levelMax;
    }

    /**
     * Set the <code>LevelMin</code> option.
     */
    public void setLevelMin(Level levelMin) {
	this.levelMin = levelMin;
    }

    /**
     * Set the <code>AcceptOnMatch</code> option.
     */
    public void setAcceptOnMatch(boolean acceptOnMatch) {
	this.acceptOnMatch = acceptOnMatch;
    }
}
