/*
    * 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.commons.monitoring.reporting.web.plugin.thread;
  
  import org.apache.commons.codec.binary.Base64;
  import org.apache.commons.lang3.StringEscapeUtils;
  import org.apache.commons.monitoring.reporting.web.handler.api.Regex;
  import org.apache.commons.monitoring.reporting.web.handler.api.Template;
  import org.apache.commons.monitoring.reporting.web.template.MapBuilder;
  
  import java.util.Map;
  import java.util.TreeMap;
  
  public class ThreadEndpoints {
      @Regex
      public Template home() {
          return new Template("threads/threads.vm", new MapBuilder<String, Object>()
                                  .set("threads", listThreads())
                                  .build());
      }
  
      @Regex("/([^/]*)")
      public Template dump(final String name) {
          final Thread thread = findThread(new String(Base64.decodeBase64(name)));
          if (thread == null) {
              return new Template("templates/threads/thread.vm", new MapBuilder<String, Object>().set("state", "Not found").build(), false);
          }
  
          return new Template(
                  "templates/threads/thread.vm",
                  new MapBuilder<String, Object>().set("state", thread.getState().name()).set("dump", StringEscapeUtils.escapeHtml4(dump(thread))).build(),
                  false);
      }
  
      private static Thread findThread(final String name) {
          int count = Thread.activeCount();
          final Thread[] threads = new Thread[count];
          count = Thread.enumerate(threads);
  
          for (int i = 0; i < count; i++) {
              if (threads[i].getName().equals(name)) {
                  return threads[i];
              }
          }
  
          return null;
      }
  
      private static String dump(final Thread thread) {
          final StackTraceElement[] stack = thread.getStackTrace();
          final StringBuilder builder = new StringBuilder();
          for (final StackTraceElement element : stack) {
              builder.append(element.toString()).append("\n"); // toString method is fine
          }
          return builder.toString();
      }
  
      private static Map<String, String> listThreads() {
          final Map<String, String> out = new TreeMap<String, String>();
  
          int count = Thread.activeCount();
          final Thread[] threads = new Thread[count];
          count = Thread.enumerate(threads);
  
          for (int i = 0; i < count; i++) {
              final String name = threads[i].getName();
              out.put(name, Base64.encodeBase64String(name.getBytes()));
          }
  
          return out;
      }
  }