/*
 * 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.felix.resolver;

import org.osgi.resource.Resource;


This class mimics the standard OSGi LogService interface. An
instance of this class is used by the framework for all logging. By default
this class logs messages to standard out. The log level can be set to control
the amount of logging performed, where a higher number results in more
logging. A log level of zero turns off logging completely.


The log levels match those specified in the OSGi Log Service (i.e., 1 =
error, 2 = warning, 3 = information, and 4 = debug). The default value is 1.


This class also uses the System Bundle's context to track log services and
will use the highest ranking log service, if present, as a back end instead
of printing to standard out. The class uses reflection to invoking the log
service's method to avoid a dependency on the log interface.

/**
 * <p>
 * This class mimics the standard OSGi <tt>LogService</tt> interface. An
 * instance of this class is used by the framework for all logging. By default
 * this class logs messages to standard out. The log level can be set to control
 * the amount of logging performed, where a higher number results in more
 * logging. A log level of zero turns off logging completely.
 * </p>
 * <p>
 * The log levels match those specified in the OSGi Log Service (i.e., 1 =
 * error, 2 = warning, 3 = information, and 4 = debug). The default value is 1.
 * </p>
 * <p>
 * This class also uses the System Bundle's context to track log services and
 * will use the highest ranking log service, if present, as a back end instead
 * of printing to standard out. The class uses reflection to invoking the log
 * service's method to avoid a dependency on the log interface.
 * </p>
 */
public class Logger
{
    public static final int LOG_ERROR = 1;
    public static final int LOG_WARNING = 2;
    public static final int LOG_INFO = 3;
    public static final int LOG_DEBUG = 4;

    private int m_logLevel = 1;

    public Logger(int i)
    {
        m_logLevel = i;
    }

    public final synchronized void setLogLevel(int i)
    {
        m_logLevel = i;
    }

    public final synchronized int getLogLevel()
    {
        return m_logLevel;
    }

    public final void log(int level, String msg)
    {
        _log(level, msg, null);
    }

    public final void log(int level, String msg, Throwable throwable)
    {
        _log(level, msg, throwable);
    }

    public boolean isDebugEnabled()
    {
        return m_logLevel >= LOG_DEBUG;
    }

    public final void debug(String msg)
    {
        _log(LOG_DEBUG, msg, null);
    }

    protected void doLog(int level, String msg, Throwable throwable)
    {
        if (level > m_logLevel)
        {
            return;
        }
        String s = msg;
        if (throwable != null)
        {
            s = s + " (" + throwable + ")";
        }
        switch (level)
        {
            case LOG_DEBUG:
                System.out.println("DEBUG: " + s);
                break;
            case LOG_ERROR:
                System.out.println("ERROR: " + s);
                if (throwable != null)
                {
                    throwable.printStackTrace();
                }
                break;
            case LOG_INFO:
                System.out.println("INFO: " + s);
                break;
            case LOG_WARNING:
                System.out.println("WARNING: " + s);
                break;
            default:
                System.out.println("UNKNOWN[" + level + "]: " + s);
        }
    }

    private void _log(
        int level,
        String msg, Throwable throwable)
    {
        if (m_logLevel >= level)
        {
            doLog(level, msg, throwable);
        }
    }

    public void logUsesConstraintViolation(Resource resource, ResolutionError error)
    {
        // do nothing by default
    }
}