/*
 * Copyright 2012 LinkedIn Corp.
 *
 * Licensed 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 azkaban.execapp;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

import javax.management.MBeanAttributeInfo;
import javax.management.MBeanInfo;
import javax.management.ObjectName;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;

import azkaban.Constants;
import azkaban.executor.ConnectorParams;
import azkaban.server.HttpRequestUtils;
import azkaban.utils.JSONUtils;

public class JMXHttpServlet extends HttpServlet implements ConnectorParams {
  private static final long serialVersionUID = -3085603824826446270L;
  private static final Logger logger = Logger.getLogger(JMXHttpServlet.class);
  private AzkabanExecutorServer server;

  @Override
  public void init(ServletConfig config) throws ServletException {
    server =
        (AzkabanExecutorServer) config.getServletContext().getAttribute(
            Constants.AZKABAN_SERVLET_CONTEXT_KEY);
  }

  public boolean hasParam(HttpServletRequest request, String param) {
    return HttpRequestUtils.hasParam(request, param);
  }

  public String getParam(HttpServletRequest request, String name)
      throws ServletException {
    return HttpRequestUtils.getParam(request, name);
  }

  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp)
      throws ServletException, IOException {
    Map<String, Object> ret = new HashMap<String, Object>();

    if (hasParam(req, JMX_GET_MBEANS)) {
      ret.put("mbeans", server.getMbeanNames());
    } else if (hasParam(req, JMX_GET_ALL_MBEAN_ATTRIBUTES)) {
      if (!hasParam(req, JMX_MBEAN)) {
        ret.put("error", "Parameters 'mbean' must be set");
      } else {
        String mbeanName = getParam(req, JMX_MBEAN);
        try {
          ObjectName name = new ObjectName(mbeanName);
          MBeanInfo info = server.getMBeanInfo(name);

          MBeanAttributeInfo[] mbeanAttrs = info.getAttributes();
          Map<String, Object> attributes = new TreeMap<String, Object>();

          for (MBeanAttributeInfo attrInfo : mbeanAttrs) {
            Object obj = server.getMBeanAttribute(name, attrInfo.getName());
            attributes.put(attrInfo.getName(), obj);
          }

          ret.put("attributes", attributes);
        } catch (Exception e) {
          logger.error(e);
          ret.put("error", "'" + mbeanName + "' is not a valid mBean name");
        }
      }
    }

    JSONUtils.toJSON(ret, resp.getOutputStream(), true);
  }
}