/**
    *
    * 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.monitoring;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.util.GsonUtil;
  import org.apache.hbase.thirdparty.com.google.gson.Gson;
  
  @InterfaceAudience.Private
  class MonitoredTaskImpl implements MonitoredTask {
    private long startTime;
    private long statusTime;
    private long stateTime;
    private long warnTime;
  
    private volatile String status;
    private volatile String description;
    
    protected volatile State state = State.RUNNING;
  
    private boolean journalEnabled = false;
    private List<StatusJournalEntry> journal;
  
    private static final Gson GSON = GsonUtil.createGson().create();
  
    public MonitoredTaskImpl() {
      startTime = System.currentTimeMillis();
      statusTime = startTime;
      stateTime = startTime;
      warnTime = startTime;
    }
  
    private static class StatusJournalEntryImpl implements StatusJournalEntry {
      private long statusTime;
      private String status;
  
      public StatusJournalEntryImpl(String status, long statusTime) {
        this.status = status;
        this.statusTime = statusTime;
      }
  
      @Override
      public String getStatus() {
        return status;
      }
  
      @Override
      public long getTimeStamp() {
        return statusTime;
      }
  
      @Override
      public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append(status);
        sb.append(" at ");
        sb.append(statusTime);
        return sb.toString();
      }
    }
  
    @Override
    public synchronized MonitoredTaskImpl clone() {
      try {
        return (MonitoredTaskImpl) super.clone();
      } catch (CloneNotSupportedException e) {
        throw new AssertionError(); // Won't happen
      }
    }
  
    @Override
    public long getStartTime() {
      return startTime;
    }
    
    @Override
    public String getDescription() {
     return description;
   }
 
   @Override
   public String getStatus() {
     return status;
   }
 
   @Override
   public long getStatusTime() {
     return statusTime;
   }
   
   @Override
   public State getState() {
     return state;
   }
   
   @Override
   public long getStateTime() {
     return stateTime;
   }
 
   @Override
   public long getWarnTime() {
     return warnTime;
   }
 
   @Override
   public long getCompletionTimestamp() {
     if (state == State.COMPLETE || state == State.ABORTED) {
       return stateTime;
     }
     return -1;
   }
 
   @Override
   public void markComplete(String status) {
     setState(State.COMPLETE);
     setStatus(status);
   }
 
   @Override
   public void pause(String msg) {
     setState(State.WAITING);
     setStatus(msg);
   }
 
   @Override
   public void resume(String msg) {
     setState(State.RUNNING);
     setStatus(msg);
   }
 
   @Override
   public void abort(String msg) {
     setStatus(msg);
     setState(State.ABORTED);
   }
   
   @Override
   public void setStatus(String status) {
     this.status = status;
     statusTime = System.currentTimeMillis();
     if (journalEnabled) {
       journal.add(new StatusJournalEntryImpl(this.status, statusTime));
     }
   }
 
   protected void setState(State state) {
     this.state = state;
     stateTime = System.currentTimeMillis();
   }
 
   @Override
   public void setDescription(String description) {
     this.description = description;
   }
 
   @Override
   public void setWarnTime(long t) {
     this.warnTime = t;
   }
 
   @Override
   public void cleanup() {
     if (state == State.RUNNING) {
       setState(State.ABORTED);
     }
   }
 
   /**
    * Force the completion timestamp backwards so that
    * it expires now.
    */
   public void expireNow() {
     stateTime -= 180 * 1000;
   }
 
   @Override
   public Map<String, Object> toMap() {
     Map<String, Object> map = new HashMap<String, Object>();
     map.put("description", getDescription());
     map.put("status", getStatus());
     map.put("state", getState());
     map.put("starttimems", getStartTime());
     map.put("statustimems", getCompletionTimestamp());
     map.put("statetimems", getCompletionTimestamp());
     return map;
   }
 
   @Override
   public String toJSON() throws IOException {
     return GSON.toJson(toMap());
   }
 
   @Override
   public String toString() {
     StringBuilder sb = new StringBuilder(512);
     sb.append(getDescription());
     sb.append(": status=");
     sb.append(getStatus());
     sb.append(", state=");
     sb.append(getState());
     sb.append(", startTime=");
     sb.append(getStartTime());
     sb.append(", completionTime=");
     sb.append(getCompletionTimestamp());
     return sb.toString();
   }
 
   /**
    * Returns the status journal. This implementation of status journal is not thread-safe. Currently
    * we use this to track various stages of flushes and compactions where we can use this/pretty
    * print for post task analysis, by which time we are already done changing states (writing to
    * journal)
    */
   @Override
   public List<StatusJournalEntry> getStatusJournal() {
     if (journal == null) {
       return Collections.emptyList();
     } else {
       return Collections.unmodifiableList(journal);
     }
   }
 
   /**
    * Enables journaling of this monitored task, the first invocation will lazily initialize the
    * journal. The journal implementation itself and this method are not thread safe
    */
   @Override
   public void enableStatusJournal(boolean includeCurrentStatus) {
     if (journalEnabled && journal != null) {
       return;
     }
     journalEnabled = true;
     if (journal == null) {
       journal = new ArrayList<StatusJournalEntry>();
     }
     if (includeCurrentStatus && status != null) {
       journal.add(new StatusJournalEntryImpl(status, statusTime));
     }
   }
 
   @Override
   public void disableStatusJournal() {
     journalEnabled = false;
   }
 
   @Override
   public String prettyPrintJournal() {
     StringBuilder sb = new StringBuilder();
     for (int i = 0; i < journal.size(); i++) {
       StatusJournalEntry je = journal.get(i);
       sb.append(je.toString());
       if (i != 0) {
         StatusJournalEntry jep = journal.get(i-1);
         long delta = je.getTimeStamp() - jep.getTimeStamp();
         if (delta != 0) {
           sb.append(" (+" + delta + " ms)");
         }
       }
       sb.append("\n");
     }
     return sb.toString();
   }
 
 }