/*
    *  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.mina.core.service;
  
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.concurrent.atomic.AtomicLong;
  
  
  /**
   * Provides usage statistics for an {@link AbstractIoService} instance.
   * 
   * @author The Apache MINA Project (dev@mina.apache.org)
   * @since 2.0.0-M3
   */
  public class IoServiceStatistics {
      
      private AbstractIoService service;
      
      private double readBytesThroughput;
      private double writtenBytesThroughput;
      private double readMessagesThroughput;
      private double writtenMessagesThroughput;
      private double largestReadBytesThroughput;
      private double largestWrittenBytesThroughput;
      private double largestReadMessagesThroughput;
      private double largestWrittenMessagesThroughput;    
      
      private final AtomicLong readBytes = new AtomicLong();
      private final AtomicLong writtenBytes = new AtomicLong();
      private final AtomicLong readMessages = new AtomicLong();
      private final AtomicLong writtenMessages = new AtomicLong();    
      private long lastReadTime;
      private long lastWriteTime;
      
      private long lastReadBytes;
      private long lastWrittenBytes;
      private long lastReadMessages;
      private long lastWrittenMessages;
      private long lastThroughputCalculationTime;
  
      private final AtomicInteger scheduledWriteBytes = new AtomicInteger();
      private final AtomicInteger scheduledWriteMessages = new AtomicInteger();
      
      private int throughputCalculationInterval = 3;
      
      private final Object throughputCalculationLock = new Object();
      
      public IoServiceStatistics(AbstractIoService service) {
          this.service = service;
      }
      
      /**
       * Returns the maximum number of sessions which were being managed at the
       * same time.
       */
      public final int getLargestManagedSessionCount() {
          return service.getListeners().getLargestManagedSessionCount();
      }
  
      /**
       * Returns the cumulative number of sessions which were managed (or are
       * being managed) by this service, which means 'currently managed session
       * count + closed session count'.
       */
      public final long getCumulativeManagedSessionCount() {
          return service.getListeners().getCumulativeManagedSessionCount();
      }
      
      /**
       * Returns the time in millis when I/O occurred lastly.
       */
      public final long getLastIoTime() {
          return Math.max(lastReadTime, lastWriteTime);
      }
  
      /**
       * Returns the time in millis when read operation occurred lastly.
       */
      public final long getLastReadTime() {
          return lastReadTime;
      }
  
     /**
      * Returns the time in millis when write operation occurred lastly.
      */
     public final long getLastWriteTime() {
         return lastWriteTime;
     }
     
     /**
      * Returns the number of bytes read by this service
      *
      * @return
      *     The number of bytes this service has read
      */
     public final long getReadBytes() {
         return readBytes.get();
     }
 
     /**
      * Returns the number of bytes written out by this service
      *
      * @return
      *     The number of bytes this service has written
      */
     public final long getWrittenBytes() {
         return writtenBytes.get();
     }
 
     /**
      * Returns the number of messages this services has read
      *
      * @return
      *     The number of messages this services has read
      */
     public final long getReadMessages() {
         return readMessages.get();
     }
 
     /**
      * Returns the number of messages this service has written
      *
      * @return
      *     The number of messages this service has written
      */
     public final long getWrittenMessages() {
         return writtenMessages.get();
     }
 
     /**
      * Returns the number of read bytes per second.
      */
     public final double getReadBytesThroughput() {
         resetThroughput();
         return readBytesThroughput;
     }
 
     /**
      * Returns the number of written bytes per second.
      */
     public final double getWrittenBytesThroughput() {
         resetThroughput();
         return writtenBytesThroughput;
     }
 
     /**
      * Returns the number of read messages per second.
      */
     public final double getReadMessagesThroughput() {
         resetThroughput();
         return readMessagesThroughput;
     }
 
     /**
      * Returns the number of written messages per second.
      */
     public final double getWrittenMessagesThroughput() {
         resetThroughput();
         return writtenMessagesThroughput;
     }
 
     /**
      * Returns the maximum of the {@link #getReadBytesThroughput() readBytesThroughput}.
      */
     public final double getLargestReadBytesThroughput() {
         return largestReadBytesThroughput;
     }
 
     /**
      * Returns the maximum of the {@link #getWrittenBytesThroughput() writtenBytesThroughput}.
      */
     public final double getLargestWrittenBytesThroughput() {
         return largestWrittenBytesThroughput;
     }
 
     /**
      * Returns the maximum of the {@link #getReadMessagesThroughput() readMessagesThroughput}.
      */
     public final double getLargestReadMessagesThroughput() {
         return largestReadMessagesThroughput;
     }
 
     /**
      * Returns the maximum of the {@link #getWrittenMessagesThroughput() writtenMessagesThroughput}.
      */
     public final double getLargestWrittenMessagesThroughput() {
         return largestWrittenMessagesThroughput;
     }
 
     /**
      * Returns the interval (seconds) between each throughput calculation.
      * The default value is <tt>3</tt> seconds.
      */
     public final int getThroughputCalculationInterval() {
         return throughputCalculationInterval;
     }
 
     /**
      * Returns the interval (milliseconds) between each throughput calculation.
      * The default value is <tt>3</tt> seconds.
      */
     public final long getThroughputCalculationIntervalInMillis() {
         return throughputCalculationInterval * 1000L;
     }
 
     /**
      * Sets the interval (seconds) between each throughput calculation.  The
      * default value is <tt>3</tt> seconds.
      */
     public final void setThroughputCalculationInterval(
             int throughputCalculationInterval) {
         if (throughputCalculationInterval < 0) {
             throw new IllegalArgumentException(
                     "throughputCalculationInterval: "
                             + throughputCalculationInterval);
         }
 
         this.throughputCalculationInterval = throughputCalculationInterval;
     }
 
     /**
      * TODO add documentation
      */
     protected final void setLastReadTime(long lastReadTime) {
         this.lastReadTime = lastReadTime;
     }
 
     /**
      * TODO add documentation
      */     
     protected final void setLastWriteTime(long lastWriteTime) {
         this.lastWriteTime = lastWriteTime;
     }
     
     /**
      * TODO add documentation
      */
     private void resetThroughput() {
         if (service.getManagedSessionCount() == 0) {
             readBytesThroughput = 0;
             writtenBytesThroughput = 0;
             readMessagesThroughput = 0;
             writtenMessagesThroughput = 0;
         }
     }
 
     /**
      * TODO add documentation
      */    
     public void updateThroughput(long currentTime) {
         synchronized (throughputCalculationLock) {
             int interval = (int) (currentTime - lastThroughputCalculationTime);
             long minInterval = getThroughputCalculationIntervalInMillis();
             if (minInterval == 0 || interval < minInterval) {
                 return;
             }
 
             long readBytes = this.readBytes.get();
             long writtenBytes = this.writtenBytes.get();
             long readMessages = this.readMessages.get();
             long writtenMessages = this.writtenMessages.get();
 
             readBytesThroughput = (readBytes - lastReadBytes) * 1000.0
                     / interval;
             writtenBytesThroughput = (writtenBytes - lastWrittenBytes) * 1000.0
                     / interval;
             readMessagesThroughput = (readMessages - lastReadMessages) * 1000.0
                     / interval;
             writtenMessagesThroughput = (writtenMessages - lastWrittenMessages)
                     * 1000.0 / interval;
 
             if (readBytesThroughput > largestReadBytesThroughput) {
                 largestReadBytesThroughput = readBytesThroughput;
             }
             if (writtenBytesThroughput > largestWrittenBytesThroughput) {
                 largestWrittenBytesThroughput = writtenBytesThroughput;
             }
             if (readMessagesThroughput > largestReadMessagesThroughput) {
                 largestReadMessagesThroughput = readMessagesThroughput;
             }
             if (writtenMessagesThroughput > largestWrittenMessagesThroughput) {
                 largestWrittenMessagesThroughput = writtenMessagesThroughput;
             }
 
             lastReadBytes = readBytes;
             lastWrittenBytes = writtenBytes;
             lastReadMessages = readMessages;
             lastWrittenMessages = writtenMessages;
 
             lastThroughputCalculationTime = currentTime;
         }
     }
     
     /**
      * TODO add documentation
      */ 
     public final void increaseReadBytes(long increment, long currentTime) {
         readBytes.addAndGet(increment);
         lastReadTime = currentTime;
     }
 
     /**
      * TODO add documentation
      */     
     public final void increaseReadMessages(long currentTime) {
         readMessages.incrementAndGet();
         lastReadTime = currentTime;
     }
     
     /**
      * TODO add documentation
      */
     public final void increaseWrittenBytes(int increment, long currentTime) {
         writtenBytes.addAndGet(increment);
         lastWriteTime = currentTime;
     }
 
     /**
      * TODO add documentation
      */    
     public final void increaseWrittenMessages(long currentTime) {
         writtenMessages.incrementAndGet();
         lastWriteTime = currentTime;
     }
     
     /**
      * TODO add documentation
      */
     public final int getScheduledWriteBytes() {
         return scheduledWriteBytes.get();
     }
 
     /**
      * TODO add documentation
      */    
     public final void increaseScheduledWriteBytes(int increment) {
         scheduledWriteBytes.addAndGet(increment);
     }
 
     /**
      * TODO add documentation
      */
     public final int getScheduledWriteMessages() {
         return scheduledWriteMessages.get();
     }
 
     /**
      * TODO add documentation
      */    
     public final void increaseScheduledWriteMessages() {
         scheduledWriteMessages.incrementAndGet();
     }
 
     /**
      * TODO add documentation
      */    
     public final void decreaseScheduledWriteMessages() {
         scheduledWriteMessages.decrementAndGet();
     }
 
     /**
      * TODO add documentation
      */        
     protected void setLastThroughputCalculationTime(
             long lastThroughputCalculationTime) {
         this.lastThroughputCalculationTime = lastThroughputCalculationTime;
     }    
 }