/*
 * 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.juli;

import java.io.File;
import java.io.FileInputStream;
import java.io.FilePermission;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessControlException;
import java.security.AccessController;
import java.security.Permission;
import java.security.PrivilegedAction;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import java.util.StringTokenizer;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.LogManager;
import java.util.logging.Logger;


/**
 * Per classloader LogManager implementation.
 *
 * For light debugging, set the system property
 * <code>org.apache.juli.ClassLoaderLogManager.debug=true</code>.
 * Short configuration information will be sent to <code>System.err</code>.
 */
public class ClassLoaderLogManager extends LogManager {
    public static final String DEBUG_PROPERTY =
            ClassLoaderLogManager.class.getName() + ".debug";

    private final class Cleaner extends Thread {
        
        @Override
        public void run() {
            if (useShutdownHook) {
                shutdown();
            }
        }

    }

    
    // ------------------------------------------------------------Constructors

    public ClassLoaderLogManager() {
        super();
        try { 
            Runtime.getRuntime().addShutdownHook(new Cleaner());
        } catch (IllegalStateException ise) {
            // We are probably already being shutdown. Ignore this error.
        }
    }


    // -------------------------------------------------------------- Variables


    /**
     * Map containing the classloader information, keyed per classloader. A
     * weak hashmap is used to ensure no classloader reference is leaked from 
     * application redeployment.
     */
    protected final Map<ClassLoader, ClassLoaderLogInfo> classLoaderLoggers = 
            new WeakHashMap<ClassLoader, ClassLoaderLogInfo>(); // Guarded by this

    
    /**
     * This prefix is used to allow using prefixes for the properties names
     * of handlers and their subcomponents.
     */
    protected ThreadLocal<String> prefix = new ThreadLocal<String>();


    /**
     * Determines if the shutdown hook is used to perform any necessary
     * clean-up such as flushing buffered handlers on JVM shutdown. Defaults to
     * <code>true</code> but may be set to false if another component ensures
     * that {@link #shutdown()} is called.
     */
    protected volatile boolean useShutdownHook = true;

    
    // ------------------------------------------------------------- Properties


    public boolean isUseShutdownHook() {
        return useShutdownHook;
    }


    public void setUseShutdownHook(boolean useShutdownHook) {
        this.useShutdownHook = useShutdownHook;
    }


    // --------------------------------------------------------- Public Methods


    /**
     * Add the specified logger to the classloader local configuration.
     * 
     * @param logger The logger to be added
     */
    @Override
    public synchronized boolean addLogger(final Logger logger) {

        final String loggerName = logger.getName();

        ClassLoader classLoader = 
            Thread.currentThread().getContextClassLoader();
        ClassLoaderLogInfo info = getClassLoaderInfo(classLoader);
        if (info.loggers.containsKey(loggerName)) {
            return false;
        }
        info.loggers.put(loggerName, logger);

        // Apply initial level for new logger
        final String levelString = getProperty(loggerName + ".level");
        if (levelString != null) {
            try {
                AccessController.doPrivileged(new PrivilegedAction<Void>() {
                    @Override
                    public Void run() {
                        logger.setLevel(Level.parse(levelString.trim()));
                        return null;
                    }
                });
            } catch (IllegalArgumentException e) {
                // Leave level set to null
            }
        }

        // Always instantiate parent loggers so that 
        // we can control log categories even during runtime
        int dotIndex = loggerName.lastIndexOf('.');
        if (dotIndex >= 0) {
            final String parentName = loggerName.substring(0, dotIndex);
            Logger.getLogger(parentName);
        }

        // Find associated node
        LogNode node = info.rootNode.findNode(loggerName);
        node.logger = logger;

        // Set parent logger
        Logger parentLogger = node.findParentLogger();
        if (parentLogger != null) {
            doSetParentLogger(logger, parentLogger);
        }

        // Tell children we are their new parent
        node.setParentLogger(logger);

        // Add associated handlers, if any are defined using the .handlers property.
        // In this case, handlers of the parent logger(s) will not be used
        String handlers = getProperty(loggerName + ".handlers");
        if (handlers != null) {
            logger.setUseParentHandlers(false);
            StringTokenizer tok = new StringTokenizer(handlers, ",");
            while (tok.hasMoreTokens()) {
                String handlerName = (tok.nextToken().trim());
                Handler handler = null;
                ClassLoader current = classLoader;
                while (current != null) {
                    info = classLoaderLoggers.get(current);
                    if (info != null) {
                        handler = info.handlers.get(handlerName);
                        if (handler != null) {
                            break;
                        }
                    }
                    current = current.getParent();
                }
                if (handler != null) {
                    logger.addHandler(handler);
                }
            }
        }

        // Parse useParentHandlers to set if the logger should delegate to its parent.
        // Unlike java.util.logging, the default is to not delegate if a list of handlers
        // has been specified for the logger.
        String useParentHandlersString = getProperty(loggerName + ".useParentHandlers");
        if (Boolean.parseBoolean(useParentHandlersString)) {
            logger.setUseParentHandlers(true);
        }
        
        return true;
    }

    
    /**
     * Get the logger associated with the specified name inside 
     * the classloader local configuration. If this returns null,
     * and the call originated for Logger.getLogger, a new
     * logger with the specified name will be instantiated and
     * added using addLogger.
     * 
     * @param name The name of the logger to retrieve
     */
    @Override
    public synchronized Logger getLogger(final String name) {
        ClassLoader classLoader = Thread.currentThread()
                .getContextClassLoader();
        return getClassLoaderInfo(classLoader).loggers.get(name);
    }
    
    
    /**
     * Get an enumeration of the logger names currently defined in the 
     * classloader local configuration.
     */
    @Override
    public synchronized Enumeration<String> getLoggerNames() {
        ClassLoader classLoader = Thread.currentThread()
                .getContextClassLoader();
        return Collections.enumeration(getClassLoaderInfo(classLoader).loggers.keySet());
    }

    
    /**
     * Get the value of the specified property in the classloader local
     * configuration.
     * 
     * @param name The property name
     */    
    @Override
    public String getProperty(String name) {
        String prefix = this.prefix.get();
        String result = null;

        // If a prefix is defined look for a prefixed property first
        if (prefix != null) {
            result = findProperty(prefix + name);
        }

        // If there is no prefix or no property match with the prefix try just
        // the name
        if (result == null) {
            result = findProperty(name);
        }

        // Simple property replacement (mostly for folder names)
        if (result != null) {
            result = replace(result);
        }
        return result;
    }


    private synchronized String findProperty(String name) {
        ClassLoader classLoader = Thread.currentThread()
                .getContextClassLoader();
        ClassLoaderLogInfo info = getClassLoaderInfo(classLoader);
        String result = info.props.getProperty(name);
        // If the property was not found, and the current classloader had no 
        // configuration (property list is empty), look for the parent classloader
        // properties.
        if ((result == null) && (info.props.isEmpty())) {
            ClassLoader current = classLoader.getParent();
            while (current != null) {
                info = classLoaderLoggers.get(current);
                if (info != null) {
                    result = info.props.getProperty(name);
                    if ((result != null) || (!info.props.isEmpty())) {
                        break;
                    }
                }
                current = current.getParent();
            }
            if (result == null) {
                result = super.getProperty(name);
            }
        }
        return result;
    }

    
    @Override
    public void readConfiguration()
        throws IOException, SecurityException {
        
        checkAccess();
        
        readConfiguration(Thread.currentThread().getContextClassLoader());
        
    }
        
    @Override
    public void readConfiguration(InputStream is)
        throws IOException, SecurityException {
        
        checkAccess();
        reset();

        readConfiguration(is, Thread.currentThread().getContextClassLoader());
    
    }

    @Override
    public void reset() throws SecurityException {
        Thread thread = Thread.currentThread();
        if (thread.getClass().getName().startsWith(
                "java.util.logging.LogManager$")) {
            // Ignore the call from java.util.logging.LogManager.Cleaner,
            // because we have our own shutdown hook
            return;
        }
        ClassLoader classLoader = thread.getContextClassLoader();
        ClassLoaderLogInfo clLogInfo = getClassLoaderInfo(classLoader);
        resetLoggers(clLogInfo);
        super.reset();
    }

    /**
     * Shuts down the logging system.
     */
    public synchronized void shutdown() {
        // The JVM is being shutdown. Make sure all loggers for all class
        // loaders are shutdown
        for (ClassLoaderLogInfo clLogInfo : classLoaderLoggers.values()) {
            resetLoggers(clLogInfo);
        }
    }

    // -------------------------------------------------------- Private Methods
    private void resetLoggers(ClassLoaderLogInfo clLogInfo) {
        // This differs from LogManager#resetLogger() in that we close not all
        // handlers of all loggers, but only those that are present in our
        // ClassLoaderLogInfo#handlers list. That is because our #addLogger(..)
        // method can use handlers from the parent class loaders, and closing
        // handlers that the current class loader does not own would be not
        // good.
        synchronized (clLogInfo) {
            for (Logger logger : clLogInfo.loggers.values()) {
                Handler[] handlers = logger.getHandlers();
                for (Handler handler : handlers) {
                    logger.removeHandler(handler);
                }
            }
            for (Handler handler : clLogInfo.handlers.values()) {
                try {
                    handler.close();
                } catch (Exception e) {
                    // Ignore
                }
            }
            clLogInfo.handlers.clear();
        }
    }

    // ------------------------------------------------------ Protected Methods


    /**
     * Retrieve the configuration associated with the specified classloader. If
     * it does not exist, it will be created.
     * 
     * @param classLoader The classloader for which we will retrieve or build the 
     *                    configuration
     */
    protected synchronized ClassLoaderLogInfo getClassLoaderInfo(ClassLoader classLoader) {
        
        if (classLoader == null) {
            classLoader = ClassLoader.getSystemClassLoader();
        }
        ClassLoaderLogInfo info = classLoaderLoggers.get(classLoader);
        if (info == null) {
            final ClassLoader classLoaderParam = classLoader;
            AccessController.doPrivileged(new PrivilegedAction<Void>() {
                @Override
                public Void run() {
                    try {
                        readConfiguration(classLoaderParam);
                    } catch (IOException e) {
                        // Ignore
                    }
                    return null;
                }
            });
            info = classLoaderLoggers.get(classLoader);
        }
        return info;
    }

    
    /**
     * Read configuration for the specified classloader.
     * 
     * @param classLoader 
     * @throws IOException Error
     */
    protected synchronized void readConfiguration(ClassLoader classLoader)
        throws IOException {
        
        InputStream is = null;
        // Special case for URL classloaders which are used in containers: 
        // only look in the local repositories to avoid redefining loggers 20 times
        try {
            if (classLoader instanceof URLClassLoader) {
                URL logConfig = ((URLClassLoader)classLoader).findResource("logging.properties");

                if(null != logConfig) {
                    if(Boolean.getBoolean(DEBUG_PROPERTY))
                        System.err.println(getClass().getName()
                                           + ".readConfiguration(): "
                                           + "Found logging.properties at "
                                           + logConfig);

                    is = classLoader.getResourceAsStream("logging.properties");
                } else {
                    if(Boolean.getBoolean(DEBUG_PROPERTY))
                        System.err.println(getClass().getName()
                                           + ".readConfiguration(): "
                                           + "Found no logging.properties");
                }
            }
        } catch (AccessControlException ace) {
            // No permission to configure logging in context
            // Log and carry on
            ClassLoaderLogInfo info = classLoaderLoggers.get(ClassLoader.getSystemClassLoader());
            if (info != null) {
                Logger log = info.loggers.get("");
                if (log != null) {
                    Permission perm = ace.getPermission();
                    if (perm instanceof FilePermission && perm.getActions().equals("read")) {
                        log.warning("Reading " + perm.getName() + " is not permitted. See \"per context logging\" in the default catalina.policy file.");
                    }
                    else {
                        log.warning("Reading logging.properties is not permitted in some context. See \"per context logging\" in the default catalina.policy file.");
                        log.warning("Original error was: " + ace.getMessage());
                    }
                }
            }
        }
        if ((is == null) && (classLoader == ClassLoader.getSystemClassLoader())) {
            String configFileStr = System.getProperty("java.util.logging.config.file");
            if (configFileStr != null) {
                try {
                    is = new FileInputStream(replace(configFileStr));
                } catch (IOException e) {
                    System.err.println("Configuration error");
                    e.printStackTrace();
                }
            }
            // Try the default JVM configuration
            if (is == null) {
                File defaultFile = new File(new File(System.getProperty("java.home"), "lib"), 
                    "logging.properties");
                try {
                    is = new FileInputStream(defaultFile);
                } catch (IOException e) {
                    System.err.println("Configuration error");
                    e.printStackTrace();
                }
            }
        }
        
        Logger localRootLogger = new RootLogger();
        if (is == null) {
            // Retrieve the root logger of the parent classloader instead
            ClassLoader current = classLoader.getParent();
            ClassLoaderLogInfo info = null;
            while (current != null && info == null) {
                info = getClassLoaderInfo(current);
                current = current.getParent();
            }
            if (info != null) {
                localRootLogger.setParent(info.rootNode.logger);
            }
        }
        ClassLoaderLogInfo info = 
            new ClassLoaderLogInfo(new LogNode(null, localRootLogger));
        classLoaderLoggers.put(classLoader, info);
        
        if (is != null) {
            readConfiguration(is, classLoader);
        }
        addLogger(localRootLogger);
        
    }
    
    
    /**
     * Load specified configuration.
     * 
     * @param is InputStream to the properties file
     * @param classLoader for which the configuration will be loaded
     * @throws IOException If something wrong happens during loading
     */
    protected synchronized void readConfiguration(InputStream is, ClassLoader classLoader)
        throws IOException {
        
        ClassLoaderLogInfo info = classLoaderLoggers.get(classLoader);
        
        try {
            info.props.load(is);
        } catch (IOException e) {
            // Report error
            System.err.println("Configuration error");
            e.printStackTrace();
        } finally {
            try {
                is.close();
            } catch (IOException ioe) {
                // Ignore
            }
        }
        
        // Create handlers for the root logger of this classloader
        String rootHandlers = info.props.getProperty(".handlers");
        String handlers = info.props.getProperty("handlers");
        Logger localRootLogger = info.rootNode.logger;
        if (handlers != null) {
            StringTokenizer tok = new StringTokenizer(handlers, ",");
            while (tok.hasMoreTokens()) {
                String handlerName = (tok.nextToken().trim());
                String handlerClassName = handlerName;
                String prefix = "";
                if (handlerClassName.length() <= 0) {
                    continue;
                }
                // Parse and remove a prefix (prefix start with a digit, such as 
                // "10WebappFooHanlder.")
                if (Character.isDigit(handlerClassName.charAt(0))) {
                    int pos = handlerClassName.indexOf('.');
                    if (pos >= 0) {
                        prefix = handlerClassName.substring(0, pos + 1);
                        handlerClassName = handlerClassName.substring(pos + 1);
                    }
                }
                try {
                    this.prefix.set(prefix);
                    Handler handler = 
                        (Handler) classLoader.loadClass(handlerClassName).newInstance();
                    // The specification strongly implies all configuration should be done 
                    // during the creation of the handler object.
                    // This includes setting level, filter, formatter and encoding.
                    this.prefix.set(null);
                    info.handlers.put(handlerName, handler);
                    if (rootHandlers == null) {
                        localRootLogger.addHandler(handler);
                    }
                } catch (Exception e) {
                    // Report error
                    System.err.println("Handler error");
                    e.printStackTrace();
                }
            }
            
        }
        
    }
    
    
    /**
     * Set parent child relationship between the two specified loggers.
     * 
     * @param logger
     * @param parent
     */
    protected static void doSetParentLogger(final Logger logger,
            final Logger parent) {
        AccessController.doPrivileged(new PrivilegedAction<Void>() {
            @Override
            public Void run() {
                logger.setParent(parent);
                return null;
            }
        });
    }

    
    /**
     * System property replacement in the given string.
     * 
     * @param str The original string
     * @return the modified string
     */
    protected String replace(String str) {
        String result = str;
        int pos_start = str.indexOf("${");
        if (pos_start >= 0) {
            StringBuilder builder = new StringBuilder();
            int pos_end = -1;
            while (pos_start >= 0) {
                builder.append(str, pos_end + 1, pos_start);
                pos_end = str.indexOf('}', pos_start + 2);
                if (pos_end < 0) {
                    pos_end = pos_start - 1;
                    break;
                }
                String propName = str.substring(pos_start + 2, pos_end);
                String replacement = propName.length() > 0 ? System
                        .getProperty(propName) : null;
                if (replacement != null) {
                    builder.append(replacement);
                } else {
                    builder.append(str, pos_start, pos_end + 1);
                }
                pos_start = str.indexOf("${", pos_end + 1);
            }
            builder.append(str, pos_end + 1, str.length());
            result = builder.toString();
        }
        return result;
    }

    // ---------------------------------------------------- LogNode Inner Class


    protected static final class LogNode {
        Logger logger;

        final Map<String, LogNode> children = 
            new HashMap<String, LogNode>();

        final LogNode parent;

        LogNode(final LogNode parent, final Logger logger) {
            this.parent = parent;
            this.logger = logger;
        }

        LogNode(final LogNode parent) {
            this(parent, null);
        }

        LogNode findNode(String name) {
            LogNode currentNode = this;
            if (logger.getName().equals(name)) {
                return this;
            }
            while (name != null) {
                final int dotIndex = name.indexOf('.');
                final String nextName;
                if (dotIndex < 0) {
                    nextName = name;
                    name = null;
                } else {
                    nextName = name.substring(0, dotIndex);
                    name = name.substring(dotIndex + 1);
                }
                LogNode childNode = currentNode.children.get(nextName);
                if (childNode == null) {
                    childNode = new LogNode(currentNode);
                    currentNode.children.put(nextName, childNode);
                }
                currentNode = childNode;
            }
            return currentNode;
        }

        Logger findParentLogger() {
            Logger logger = null;
            LogNode node = parent;
            while (node != null && logger == null) {
                logger = node.logger;
                node = node.parent;
            }
            return logger;
        }

        void setParentLogger(final Logger parent) {
            for (final Iterator<LogNode> iter =
                children.values().iterator(); iter.hasNext();) {
                final LogNode childNode = iter.next();
                if (childNode.logger == null) {
                    childNode.setParentLogger(parent);
                } else {
                    doSetParentLogger(childNode.logger, parent);
                }
            }
        }

    }


    // -------------------------------------------- ClassLoaderInfo Inner Class


    protected static final class ClassLoaderLogInfo {
        final LogNode rootNode;
        final Map<String, Logger> loggers = new ConcurrentHashMap<String, Logger>();
        final Map<String, Handler> handlers = new HashMap<String, Handler>();
        final Properties props = new Properties();

        ClassLoaderLogInfo(final LogNode rootNode) {
            this.rootNode = rootNode;
        }

    }


    // ------------------------------------------------- RootLogger Inner Class


    /**
     * This class is needed to instantiate the root of each per classloader 
     * hierarchy.
     */
    protected static class RootLogger extends Logger {
        public RootLogger() {
            super("", null);
        }
    }


}
