/*
    * 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.logging.log4j.message;
  
  import java.io.InvalidObjectException;
  import java.io.ObjectInputStream;
  import java.io.Serializable;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.ServiceConfigurationError;
  import java.util.ServiceLoader;
  
  import org.apache.logging.log4j.status.StatusLogger;
  import org.apache.logging.log4j.util.StringBuilderFormattable;
  import org.apache.logging.log4j.util.Strings;
  
  /**
   * Captures information about all running Threads.
   */
  @AsynchronouslyFormattable
  public class ThreadDumpMessage implements Message, StringBuilderFormattable {
      private static final long serialVersionUID = -1103400781608841088L;
      private static ThreadInfoFactory FACTORY;
  
      private volatile Map<ThreadInformation, StackTraceElement[]> threads;
      private final String title;
      private String formattedMessage;
  
      /**
       * Generate a ThreadDumpMessage with a title.
       * @param title The title.
       */
      public ThreadDumpMessage(final String title) {
          this.title = title == null ? Strings.EMPTY : title;
          threads = getFactory().createThreadInfo();
      }
  
      private ThreadDumpMessage(final String formattedMsg, final String title) {
          this.formattedMessage = formattedMsg;
          this.title = title == null ? Strings.EMPTY : title;
      }
  
      private static ThreadInfoFactory getFactory() {
          if (FACTORY == null) {
              FACTORY = initFactory(ThreadDumpMessage.class.getClassLoader());
          }
          return FACTORY;
      }
  
      private static ThreadInfoFactory initFactory(final ClassLoader classLoader) {
          final ServiceLoader<ThreadInfoFactory> serviceLoader = ServiceLoader.load(ThreadInfoFactory.class, classLoader);
          ThreadInfoFactory result = null;
          try {
              final Iterator<ThreadInfoFactory> iterator = serviceLoader.iterator();
              while (result == null && iterator.hasNext()) {
                  result = iterator.next();
              }
          } catch (ServiceConfigurationError | LinkageError | Exception unavailable) { // if java management classes not available
              StatusLogger.getLogger().info("ThreadDumpMessage uses BasicThreadInfoFactory: " +
                              "could not load extended ThreadInfoFactory: {}", unavailable.toString());
              result = null;
          }
          return result == null ? new BasicThreadInfoFactory() : result;
      }
  
      @Override
      public String toString() {
          return getFormattedMessage();
      }
  
      /**
       * Returns the ThreadDump in printable format.
       * @return the ThreadDump suitable for logging.
       */
      @Override
      public String getFormattedMessage() {
          if (formattedMessage != null) {
              return formattedMessage;
          }
          final StringBuilder sb = new StringBuilder(255);
          formatTo(sb);
          return sb.toString();
      }
  
     @Override
     public void formatTo(final StringBuilder sb) {
         sb.append(title);
         if (title.length() > 0) {
             sb.append('\n');
         }
         for (final Map.Entry<ThreadInformation, StackTraceElement[]> entry : threads.entrySet()) {
             final ThreadInformation info = entry.getKey();
             info.printThreadInfo(sb);
             info.printStack(sb, entry.getValue());
             sb.append('\n');
         }
     }
 
     /**
      * Returns the title.
      * @return the title.
      */
     @Override
     public String getFormat() {
         return title == null ? Strings.EMPTY : title;
     }
 
     /**
      * Returns an array with a single element, a Map containing the ThreadInformation as the key.
      * and the StackTraceElement array as the value;
      * @return the "parameters" to this Message.
      */
     @Override
     public Object[] getParameters() {
         return null;
     }
 
         /**
      * Creates a ThreadDumpMessageProxy that can be serialized.
      * @return a ThreadDumpMessageProxy.
      */
     protected Object writeReplace() {
         return new ThreadDumpMessageProxy(this);
     }
 
     private void readObject(final ObjectInputStream stream)
         throws InvalidObjectException {
         throw new InvalidObjectException("Proxy required");
     }
 
     /**
      * Proxy pattern used to serialize the ThreadDumpMessage.
      */
     private static class ThreadDumpMessageProxy implements Serializable {
 
         private static final long serialVersionUID = -3476620450287648269L;
         private final String formattedMsg;
         private final String title;
 
         ThreadDumpMessageProxy(final ThreadDumpMessage msg) {
             this.formattedMsg = msg.getFormattedMessage();
             this.title = msg.title;
         }
 
         /**
          * Returns a ThreadDumpMessage using the data in the proxy.
          * @return a ThreadDumpMessage.
          */
         protected Object readResolve() {
             return new ThreadDumpMessage(formattedMsg, title);
         }
     }
 
     /**
      * Factory to create Thread information.
      * <p>
      * Implementations of this class are loaded via the standard java Service Provider interface.
      * </p>
      * @see /log4j-core/src/main/resources/META-INF/services/org.apache.logging.log4j.message.ThreadDumpMessage$ThreadInfoFactory
      */
     public static interface ThreadInfoFactory {
         Map<ThreadInformation, StackTraceElement[]> createThreadInfo();
     }
 
     /**
      * Factory to create basic thread information.
      */
     private static class BasicThreadInfoFactory implements ThreadInfoFactory {
         @Override
         public Map<ThreadInformation, StackTraceElement[]> createThreadInfo() {
             final Map<Thread, StackTraceElement[]> map = Thread.getAllStackTraces();
             final Map<ThreadInformation, StackTraceElement[]> threads =
                 new HashMap<>(map.size());
             for (final Map.Entry<Thread, StackTraceElement[]> entry : map.entrySet()) {
                 threads.put(new BasicThreadInformation(entry.getKey()), entry.getValue());
             }
             return threads;
         }
     }
 
     /**
      * Always returns null.
      *
      * @return null
      */
     @Override
     public Throwable getThrowable() {
         return null;
     }
 }