package org.infinispan.jcache;

import java.util.Set;

import javax.cache.CacheException;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;

/**
 * A convenience class for registering CacheStatisticsMBeans with an
 * MBeanServer.
 *
 * @author Greg Luck
 * @since 1.0
 */
public final class RIMBeanServerRegistrationUtility {

   /**
    * The type of registered Object
    */
   //TODO: was package-level initially
   public enum ObjectNameType {

      /**
       * Cache Statistics
       */
      STATISTICS("Statistics"),

      /**
       * Cache Configuration
       */
      CONFIGURATION("Configuration");

      private final String objectName;

      ObjectNameType(String objectName) {
         this.objectName = objectName;
      }
   }


   private RIMBeanServerRegistrationUtility() {
      //prevent construction
   }

   /**
    * Utility method for registering CacheStatistics with the platform
    * MBeanServer
    *
    * @param cache the cache to register
    */
   //TODO: was package-level originally
   public static <K, V> void registerCacheObject(AbstractJCache<K, V> cache, ObjectNameType objectNameType) {
      //these can change during runtime, so always look it up
      MBeanServer mBeanServer = cache.getMBeanServer();
      ObjectName registeredObjectName = calculateObjectName(cache, objectNameType);
      try {
         if (objectNameType.equals(ObjectNameType.CONFIGURATION)) {
            if (!isRegistered(cache, objectNameType)) {
               mBeanServer.registerMBean(cache.getCacheMXBean(), registeredObjectName);
            }
         } else if (objectNameType.equals(ObjectNameType.STATISTICS)) {
            if (!isRegistered(cache, objectNameType)) {
               mBeanServer.registerMBean(cache.getCacheStatisticsMXBean(), registeredObjectName);
            }
         }
      } catch (Exception e) {
         throw new CacheException("Error registering cache MXBeans for CacheManager "
               + registeredObjectName + " . Error was " + e.getMessage(), e);
      }
   }

   /**
    * Checks whether an ObjectName is already registered.
    *
    * @throws javax.cache.CacheException - all exceptions are wrapped in
    *                                    CacheException
    */
   static <K, V> boolean isRegistered(AbstractJCache<K, V> cache, ObjectNameType objectNameType) {
      Set<ObjectName> registeredObjectNames;
      MBeanServer mBeanServer = cache.getMBeanServer();

      ObjectName objectName = calculateObjectName(cache, objectNameType);
      registeredObjectNames = mBeanServer.queryNames(objectName, null);

      return !registeredObjectNames.isEmpty();
   }

   /**
    * Removes registered CacheStatistics for a Cache
    *
    * @throws javax.cache.CacheException - all exceptions are wrapped in
    *                                    CacheException
    */
   //TODO: was package-level initially
   public static <K, V> void unregisterCacheObject(AbstractJCache<K, V> cache, ObjectNameType objectNameType) {
      Set<ObjectName> registeredObjectNames;
      MBeanServer mBeanServer = cache.getMBeanServer();

      ObjectName objectName = calculateObjectName(cache, objectNameType);
      registeredObjectNames = mBeanServer.queryNames(objectName, null);

      //should just be one
      for (ObjectName registeredObjectName : registeredObjectNames) {
         try {
            mBeanServer.unregisterMBean(registeredObjectName);
         } catch (Exception e) {
            throw new CacheException("Error unregistering object instance "
                  + registeredObjectName + " . Error was " + e.getMessage(), e);
         }
      }
   }

   /**
    * Creates an object name using the scheme "javax.cache:type=Cache&lt;Statistics|Configuration&gt;,CacheManager=&lt;cacheManagerName&gt;,name=&lt;cacheName&gt;"
    */
   private static <K, V> ObjectName calculateObjectName(AbstractJCache<K, V> cache, ObjectNameType objectNameType) {
      String cacheManagerName = mbeanSafe(cache.getCacheManager().getURI().toString());
      String cacheName = mbeanSafe(cache.getName());

      try {
         return new ObjectName("javax.cache:type=Cache" + objectNameType.objectName
               + ",CacheManager=" + cacheManagerName
               + ",Cache=" + cacheName);
      } catch (MalformedObjectNameException e) {
         throw new CacheException("Illegal ObjectName for Management Bean. " +
               "CacheManager=[" + cacheManagerName + "], Cache=[" + cacheName + "]", e);
      }
   }

   /**
    * Filter out invalid ObjectName characters from string.
    *
    * @param string input string
    * @return A valid JMX ObjectName attribute value.
    */
   private static String mbeanSafe(String string) {
      return string == null ? "" : string.replaceAll(",|:|=|\n", ".");
   }

}
