/**
 * 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.activemq.broker.jmx;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import javax.management.InstanceAlreadyExistsException;
import javax.management.MBeanAttributeInfo;
import javax.management.MBeanOperationInfo;
import javax.management.MBeanParameterInfo;
import javax.management.MBeanRegistrationException;
import javax.management.MBeanServer;
import javax.management.NotCompliantMBeanException;
import javax.management.ObjectName;
import javax.management.StandardMBean;

/**
 * MBean that looks for method/parameter descriptions in the Info annotation.
 */
public class AnnotatedMBean extends StandardMBean {

  private static final Map<String, Class<?>> primitives = new HashMap<String, Class<?>>();
  static {
    Class<?>[] p = { byte.class, short.class, int.class, long.class, float.class, double.class, char.class, boolean.class, };
    for (Class<?> c : p)
      primitives.put(c.getName(), c);
  }
  
  @SuppressWarnings("unchecked")
  public static void registerMBean(ManagementContext context, Object object, ObjectName objectName) 
    throws Exception {

    String mbeanName = object.getClass().getName() + "MBean";
    
    for (Class c : object.getClass().getInterfaces()) {
      if (mbeanName.equals(c.getName())) {
        context.registerMBean(new AnnotatedMBean(object, c), objectName);
        return;
      }
    }

    context.registerMBean(object, objectName);
  }
  
  /** Instance where the MBean interface is implemented by another object. */
  public <T> AnnotatedMBean(T impl, Class<T> mbeanInterface) throws NotCompliantMBeanException {
    super(impl, mbeanInterface);
  }

  /** Instance where the MBean interface is implemented by this object. */
  protected AnnotatedMBean(Class<?> mbeanInterface) throws NotCompliantMBeanException {
    super(mbeanInterface);
  }

  /** {@inheritDoc} */
  @Override
  protected String getDescription(MBeanAttributeInfo info) {

    String descr = info.getDescription();
    Method m = getMethod(getMBeanInterface(), "get"+info.getName().substring(0, 1).toUpperCase()+info.getName().substring(1));
    if (m == null)
      m = getMethod(getMBeanInterface(), "is"+info.getName().substring(0, 1).toUpperCase()+info.getName().substring(1));
    if (m == null)
      m = getMethod(getMBeanInterface(), "does"+info.getName().substring(0, 1).toUpperCase()+info.getName().substring(1));
      
    if (m != null) {
      MBeanInfo d = m.getAnnotation(MBeanInfo.class);
      if (d != null)
        descr = d.value();
    }
    return descr;
  }
  
  /** {@inheritDoc} */
  @Override
  protected String getDescription(MBeanOperationInfo op) {

    String descr = op.getDescription();
    Method m = getMethod(op);
    if (m != null) {
      MBeanInfo d = m.getAnnotation(MBeanInfo.class);
      if (d != null)
        descr = d.value();
    }
    return descr;
  }

  /** {@inheritDoc} */
  @Override
  protected String getParameterName(MBeanOperationInfo op, MBeanParameterInfo param, int paramNo) {
    String name = param.getName();
    Method m = getMethod(op);
    if (m != null) {
      for (Annotation a : m.getParameterAnnotations()[paramNo]) {
        if (MBeanInfo.class.isInstance(a))
          name = MBeanInfo.class.cast(a).value();
      }
    }
    return name;
  }

  /**
   * Extracts the Method from the MBeanOperationInfo
   * @param op
   * @return
   */
  private Method getMethod(MBeanOperationInfo op) {
    final MBeanParameterInfo[] params = op.getSignature();
    final String[] paramTypes = new String[params.length];
    for (int i = 0; i < params.length; i++)
      paramTypes[i] = params[i].getType();

    return getMethod(getMBeanInterface(), op.getName(), paramTypes);
  }

  /**
   * Returns the Method with the specified name and parameter types for the given class,
   * null if it doesn't exist.
   * @param mbean
   * @param method
   * @param params
   * @return
   */
  private static Method getMethod(Class<?> mbean, String method, String... params) {
    try {
      final ClassLoader loader = mbean.getClassLoader();
      final Class<?>[] paramClasses = new Class<?>[params.length];
      for (int i = 0; i < params.length; i++) {
        paramClasses[i] = primitives.get(params[i]);
        if (paramClasses[i] == null)
          paramClasses[i] = Class.forName(params[i], false, loader);
      }
      return mbean.getMethod(method, paramClasses);
    } catch (RuntimeException e) {
      throw e;
    } catch (Exception e) {
      return null;
    }
  }
}
