/*
    * 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.hadoop.hbase.util;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.io.StringWriter;
  import java.lang.management.ManagementFactory;
  import java.lang.reflect.Array;
  import java.util.Iterator;
  import java.util.Set;
  
  import javax.management.AttributeNotFoundException;
  import javax.management.InstanceNotFoundException;
  import javax.management.IntrospectionException;
  import javax.management.MBeanAttributeInfo;
  import javax.management.MBeanException;
  import javax.management.MBeanInfo;
  import javax.management.MBeanServer;
  import javax.management.MalformedObjectNameException;
  import javax.management.ObjectName;
  import javax.management.ReflectionException;
  import javax.management.RuntimeErrorException;
  import javax.management.RuntimeMBeanException;
  import javax.management.openmbean.CompositeData;
  import javax.management.openmbean.CompositeType;
  import javax.management.openmbean.TabularData;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.codehaus.jackson.JsonFactory;
  import org.codehaus.jackson.JsonGenerationException;
  import org.codehaus.jackson.JsonGenerator;
  
  /**
   * Utility for doing JSON and MBeans.
   */
  public class JSONBean {
    private static final Log LOG = LogFactory.getLog(JSONBean.class);
    private final JsonFactory jsonFactory;
  
    public JSONBean() {
      this.jsonFactory = new JsonFactory();
    }
  
    /**
     * Use dumping out mbeans as JSON.
     */
    public interface Writer extends Closeable {
      void write(final String key, final String value) throws JsonGenerationException, IOException;
      int write(final MBeanServer mBeanServer, ObjectName qry, String attribute,
          final boolean description) throws IOException;
      void flush() throws IOException;
    }
  
    public Writer open(final PrintWriter writer) throws IOException {
      final JsonGenerator jg = jsonFactory.createJsonGenerator(writer);
      jg.disable(JsonGenerator.Feature.AUTO_CLOSE_TARGET);
      jg.useDefaultPrettyPrinter();
      jg.writeStartObject();
      return new Writer() {
        @Override
        public void flush() throws IOException {
          jg.flush();
        }
  
        @Override
        public void close() throws IOException {
          jg.close();
        }
  
        @Override
        public void write(String key, String value) throws JsonGenerationException, IOException {
          jg.writeStringField(key, value);
        }
  
        @Override
        public int write(MBeanServer mBeanServer, ObjectName qry, String attribute,
            boolean description)
        throws IOException {
          return JSONBean.write(jg, mBeanServer, qry, attribute, description);
        }
      };
    }
 
   /**
    * @param mBeanServer
    * @param qry
    * @param attribute
    * @param description
    * @return Return non-zero if failed to find bean. 0
    * @throws IOException
    */
   private static int write(final JsonGenerator jg,
       final MBeanServer mBeanServer, ObjectName qry, String attribute,
       final boolean description)
   throws IOException {
     LOG.trace("Listing beans for "+qry);
     Set<ObjectName> names = null;
     names = mBeanServer.queryNames(qry, null);
     jg.writeArrayFieldStart("beans");
     Iterator<ObjectName> it = names.iterator();
     while (it.hasNext()) {
       ObjectName oname = it.next();
       MBeanInfo minfo;
       String code = "";
       String descriptionStr = null;
       Object attributeinfo = null;
       try {
         minfo = mBeanServer.getMBeanInfo(oname);
         code = minfo.getClassName();
         if (description) descriptionStr = minfo.getDescription();
         String prs = "";
         try {
           if ("org.apache.commons.modeler.BaseModelMBean".equals(code)) {
             prs = "modelerType";
             code = (String) mBeanServer.getAttribute(oname, prs);
           }
           if (attribute != null) {
             prs = attribute;
             attributeinfo = mBeanServer.getAttribute(oname, prs);
           }
         } catch (RuntimeMBeanException e) {
          // UnsupportedOperationExceptions happen in the normal course of business,
          // so no need to log them as errors all the time.
          if (e.getCause() instanceof UnsupportedOperationException) {
            if (LOG.isTraceEnabled()) {
              LOG.trace("Getting attribute " + prs + " of " + oname + " threw " + e);
            }
          } else {
            LOG.error("Getting attribute " + prs + " of " + oname + " threw an exception", e);
          }
          return 0;
         } catch (AttributeNotFoundException e) {
           // If the modelerType attribute was not found, the class name is used
           // instead.
           LOG.error("getting attribute " + prs + " of " + oname
               + " threw an exception", e);
         } catch (MBeanException e) {
           // The code inside the attribute getter threw an exception so log it,
           // and fall back on the class name
           LOG.error("getting attribute " + prs + " of " + oname
               + " threw an exception", e);
         } catch (RuntimeException e) {
           // For some reason even with an MBeanException available to them
           // Runtime exceptionscan still find their way through, so treat them
           // the same as MBeanException
           LOG.error("getting attribute " + prs + " of " + oname
               + " threw an exception", e);
         } catch (ReflectionException e) {
           // This happens when the code inside the JMX bean (setter?? from the
           // java docs) threw an exception, so log it and fall back on the
           // class name
           LOG.error("getting attribute " + prs + " of " + oname
               + " threw an exception", e);
         }
       } catch (InstanceNotFoundException e) {
         //Ignored for some reason the bean was not found so don't output it
         continue;
       } catch (IntrospectionException e) {
         // This is an internal error, something odd happened with reflection so
         // log it and don't output the bean.
         LOG.error("Problem while trying to process JMX query: " + qry
             + " with MBean " + oname, e);
         continue;
       } catch (ReflectionException e) {
         // This happens when the code inside the JMX bean threw an exception, so
         // log it and don't output the bean.
         LOG.error("Problem while trying to process JMX query: " + qry
             + " with MBean " + oname, e);
         continue;
       }
 
       jg.writeStartObject();
       jg.writeStringField("name", oname.toString());
       if (description && descriptionStr != null && descriptionStr.length() > 0) {
         jg.writeStringField("description", descriptionStr);
       }
       jg.writeStringField("modelerType", code);
       if (attribute != null && attributeinfo == null) {
         jg.writeStringField("result", "ERROR");
         jg.writeStringField("message", "No attribute with name " + attribute + " was found.");
         jg.writeEndObject();
         jg.writeEndArray();
         jg.close();
         return -1;
       }
 
       if (attribute != null) {
         writeAttribute(jg, attribute, descriptionStr, attributeinfo);
       } else {
         MBeanAttributeInfo[] attrs = minfo.getAttributes();
         for (int i = 0; i < attrs.length; i++) {
           writeAttribute(jg, mBeanServer, oname, description, attrs[i]);
         }
       }
       jg.writeEndObject();
     }
     jg.writeEndArray();
     return 0;
   }
 
   private static void writeAttribute(final JsonGenerator jg,
       final MBeanServer mBeanServer, ObjectName oname,
       final boolean description, final MBeanAttributeInfo attr)
   throws IOException {
     if (!attr.isReadable()) {
       return;
     }
     String attName = attr.getName();
     if ("modelerType".equals(attName)) {
       return;
     }
     if (attName.indexOf("=") >= 0 || attName.indexOf(":") >= 0 || attName.indexOf(" ") >= 0) {
       return;
     }
     String descriptionStr = description? attr.getDescription(): null;
     Object value = null;
     try {
       value = mBeanServer.getAttribute(oname, attName);
     } catch (RuntimeMBeanException e) {
       // UnsupportedOperationExceptions happen in the normal course of business,
       // so no need to log them as errors all the time.
       if (e.getCause() instanceof UnsupportedOperationException) {
         if (LOG.isTraceEnabled()) {
           LOG.trace("Getting attribute " + attName + " of " + oname + " threw " + e);
         }
       } else {
         LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
       }
       return;
     } catch (RuntimeErrorException e) {
       // RuntimeErrorException happens when an unexpected failure occurs in getAttribute
       // for example https://issues.apache.org/jira/browse/DAEMON-120
       LOG.debug("getting attribute "+attName+" of "+oname+" threw an exception", e);
       return;
     } catch (AttributeNotFoundException e) {
       //Ignored the attribute was not found, which should never happen because the bean
       //just told us that it has this attribute, but if this happens just don't output
       //the attribute.
       return;
     } catch (MBeanException e) {
       //The code inside the attribute getter threw an exception so log it, and
       // skip outputting the attribute
       LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
       return;
     } catch (RuntimeException e) {
       //For some reason even with an MBeanException available to them Runtime exceptions
       //can still find their way through, so treat them the same as MBeanException
       LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
       return;
     } catch (ReflectionException e) {
       //This happens when the code inside the JMX bean (setter?? from the java docs)
       //threw an exception, so log it and skip outputting the attribute
       LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
       return;
     } catch (InstanceNotFoundException e) {
       //Ignored the mbean itself was not found, which should never happen because we
       //just accessed it (perhaps something unregistered in-between) but if this
       //happens just don't output the attribute.
       return;
     }
 
     writeAttribute(jg, attName, descriptionStr, value);
   }
 
   private static void writeAttribute(JsonGenerator jg, String attName, final String descriptionStr,
       Object value)
   throws IOException {
     boolean description = false;
     if (descriptionStr != null && descriptionStr.length() > 0 && !attName.equals(descriptionStr)) {
       description = true;
       jg.writeFieldName(attName);
       jg.writeStartObject();
       jg.writeFieldName("description");
       jg.writeString(descriptionStr);
       jg.writeFieldName("value");
       writeObject(jg, description, value);
       jg.writeEndObject();
     } else {
       jg.writeFieldName(attName);
       writeObject(jg, description, value);
     }
   }
 
   private static void writeObject(final JsonGenerator jg, final boolean description, Object value)
   throws IOException {
     if(value == null) {
       jg.writeNull();
     } else {
       Class<?> c = value.getClass();
       if (c.isArray()) {
         jg.writeStartArray();
         int len = Array.getLength(value);
         for (int j = 0; j < len; j++) {
           Object item = Array.get(value, j);
           writeObject(jg, description, item);
         }
         jg.writeEndArray();
       } else if(value instanceof Number) {
         Number n = (Number)value;
         jg.writeNumber(n.toString());
       } else if(value instanceof Boolean) {
         Boolean b = (Boolean)value;
         jg.writeBoolean(b);
       } else if(value instanceof CompositeData) {
         CompositeData cds = (CompositeData)value;
         CompositeType comp = cds.getCompositeType();
         Set<String> keys = comp.keySet();
         jg.writeStartObject();
         for (String key: keys) {
           writeAttribute(jg, key, null, cds.get(key));
         }
         jg.writeEndObject();
       } else if(value instanceof TabularData) {
         TabularData tds = (TabularData)value;
         jg.writeStartArray();
         for(Object entry : tds.values()) {
           writeObject(jg, description, entry);
         }
         jg.writeEndArray();
       } else {
         jg.writeString(value.toString());
       }
     }
   }
 
   /**
    * Dump out a subset of regionserver mbeans only, not all of them, as json on System.out.
    * @throws MalformedObjectNameException
    * @throws IOException
    */
   public static String dumpRegionServerMetrics() throws MalformedObjectNameException, IOException {
     StringWriter sw = new StringWriter(1024 * 100); // Guess this size
     try (PrintWriter writer = new PrintWriter(sw)) {
       JSONBean dumper = new JSONBean();
       try (JSONBean.Writer jsonBeanWriter = dumper.open(writer)) {
         MBeanServer mbeanServer = ManagementFactory.getPlatformMBeanServer();
         jsonBeanWriter.write(mbeanServer,
           new ObjectName("java.lang:type=Memory"), null, false);
         jsonBeanWriter.write(mbeanServer,
           new ObjectName("Hadoop:service=HBase,name=RegionServer,sub=IPC"), null, false);
         jsonBeanWriter.write(mbeanServer,
           new ObjectName("Hadoop:service=HBase,name=RegionServer,sub=Replication"), null, false);
         jsonBeanWriter.write(mbeanServer,
           new ObjectName("Hadoop:service=HBase,name=RegionServer,sub=Server"), null, false);
       }
     }
     sw.close();
     return sw.toString();
   }
 
   /**
    * Dump out all registered mbeans as json on System.out.
    * @throws IOException
    * @throws MalformedObjectNameException
    */
   public static void dumpAllBeans() throws IOException, MalformedObjectNameException {
     try (PrintWriter writer = new PrintWriter(System.out)) {
       JSONBean dumper = new JSONBean();
       try (JSONBean.Writer jsonBeanWriter = dumper.open(writer)) {
         MBeanServer mbeanServer = ManagementFactory.getPlatformMBeanServer();
         jsonBeanWriter.write(mbeanServer, new ObjectName("*:*"), null, false);
       }
     }
   }
 
   public static void main(String[] args) throws IOException, MalformedObjectNameException {
     String str = dumpRegionServerMetrics();
     System.out.println(str);
   }
 }