/**
 * 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.cxf.common.logging;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.LogRecord;

import org.apache.log4j.Appender;
import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.Priority;
import org.apache.log4j.spi.LoggingEvent;

/**
 * java.util.logging.Logger implementation delegating to Log4j.
 * All methods can be used except:
 *   setLevel
 *   addHandler / getHandlers
 *   setParent / getParent
 *   setUseParentHandlers / getUseParentHandlers
 *
 * @author gnodet
 */
public class Log4jLogger extends AbstractDelegatingLogger {
    private static final Map<Level, org.apache.log4j.Level> TO_LOG4J = 
                                                new HashMap<Level, org.apache.log4j.Level>();
    private static final org.apache.log4j.Level TRACE;


    private final org.apache.log4j.Logger log;

    static {        
        //older versions of log4j don't have TRACE, use debug
        org.apache.log4j.Level t = org.apache.log4j.Level.DEBUG;
        try {
            Field f = org.apache.log4j.Level.class.getField("TRACE");
            t = (org.apache.log4j.Level)f.get(null);
        } catch (Throwable ex) {
            //ignore, assume old version of log4j
        }
        TRACE = t;
        
        TO_LOG4J.put(Level.ALL,     org.apache.log4j.Level.ALL);
        TO_LOG4J.put(Level.SEVERE,  org.apache.log4j.Level.ERROR);
        TO_LOG4J.put(Level.WARNING, org.apache.log4j.Level.WARN);
        TO_LOG4J.put(Level.INFO,    org.apache.log4j.Level.INFO);
        TO_LOG4J.put(Level.CONFIG,  org.apache.log4j.Level.DEBUG);
        TO_LOG4J.put(Level.FINE,    org.apache.log4j.Level.DEBUG);
        TO_LOG4J.put(Level.FINER,   TRACE);
        TO_LOG4J.put(Level.FINEST,  TRACE);
        TO_LOG4J.put(Level.OFF,     org.apache.log4j.Level.OFF);
    }

    public Log4jLogger(String name, String resourceBundleName) {
        super(name, resourceBundleName);
        log = org.apache.log4j.LogManager.getLogger(name);
    }

    public Level getLevel() {
        org.apache.log4j.Level l = log.getEffectiveLevel();
        if (l != null) {
            return fromL4J(l);
        }
        return null;
    }
    
    public void setLevel(Level newLevel) throws SecurityException {
        log.setLevel(TO_LOG4J.get(newLevel));
    }
    
    public synchronized void addHandler(Handler handler) throws SecurityException {
        log.addAppender(new HandlerWrapper(handler));
    }
    public synchronized void removeHandler(Handler handler) throws SecurityException {
        log.removeAppender("HandlerWrapper-" + handler.hashCode());
    }
    public synchronized Handler[] getHandlers() {
        List<Handler> ret = new ArrayList<Handler>();
        Enumeration en = log.getAllAppenders();
        while (en.hasMoreElements()) {
            Appender ap = (Appender)en.nextElement();
            if (ap instanceof HandlerWrapper) {
                ret.add(((HandlerWrapper)ap).getHandler());
            }
        }
        return ret.toArray(new Handler[ret.size()]);
    }
    
    protected void internalLogFormatted(String msg, LogRecord record) {
        log.log(AbstractDelegatingLogger.class.getName(),
                TO_LOG4J.get(record.getLevel()),
                msg,
                record.getThrown());
    }


    private Level fromL4J(org.apache.log4j.Level l) {
        Level l2 = null;
        switch (l.toInt()) {
        case org.apache.log4j.Level.ALL_INT:
            l2 = Level.ALL;
            break;
        case org.apache.log4j.Level.FATAL_INT:
            l2 = Level.SEVERE;
            break;
        case org.apache.log4j.Level.ERROR_INT:
            l2 = Level.SEVERE;
            break;
        case org.apache.log4j.Level.WARN_INT:
            l2 = Level.WARNING;
            break;
        case org.apache.log4j.Level.INFO_INT:
            l2 = Level.INFO;
            break;
        case org.apache.log4j.Level.DEBUG_INT:
            l2 = Level.FINE;
            break;
        case org.apache.log4j.Level.OFF_INT:
            l2 = Level.OFF;
            break;
        default:
            if (l.toInt() == TRACE.toInt()) {
                l2 = Level.FINEST;
            } else {
                l2 = null;
            }
        } 
        return l2;
    } 
    
    
    private class HandlerWrapper extends AppenderSkeleton {
        Handler handler;
        
        public HandlerWrapper(Handler h) {
            handler = h;
            name = "HandlerWrapper-" + h.hashCode(); 
        }
        
        public Handler getHandler() {
            return handler;
        }

        @Override
        protected void append(LoggingEvent event) {
            LogRecord lr = new LogRecord(fromL4J(event.getLevel()),
                                         event.getMessage().toString());
            lr.setLoggerName(event.getLoggerName());
            if (event.getThrowableInformation() != null) {
                lr.setThrown(event.getThrowableInformation().getThrowable());
            }
            String rbname = getResourceBundleName();
            if (rbname != null) {
                lr.setResourceBundleName(rbname);
                lr.setResourceBundle(getResourceBundle());
            }
            getFullInfoForLogUtils(lr, event.fqnOfCategoryClass);
            handler.publish(lr);
        }

        public void close() {
            handler.close();
            closed = true;
        }

        public boolean requiresLayout() {
            return false;
        }    
        
        @Override
        public Priority getThreshold() {
            return TO_LOG4J.get(handler.getLevel());
        }
        @Override
        public boolean isAsSevereAsThreshold(Priority priority) {
            Priority p = getThreshold();
            return (p == null) || priority.isGreaterOrEqual(p);
        }        
    }
    private static void getFullInfoForLogUtils(LogRecord lr, String cname) {
        StackTraceElement el[] = Thread.currentThread().getStackTrace();
        for (int x = el.length - 2; x >= 0; x--) {
            if (LogUtils.class.getName().equals(el[x].getClassName())
                || cname.equals(el[x].getClassName())) {
                lr.setSourceClassName(el[x + 1].getClassName());
                lr.setSourceMethodName(el[x + 1].getMethodName());
                return;
            }
        }
    }
}
