/*
    * 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.chukwa.datacollection.connector.http;
  
  
  /**
   * This class is responsible for setting up a {@link HttpConnectorClient} with a  collectors
   * and then repeatedly calling its send function which encapsulates the work of setting up the
   * connection with the appropriate collector and then collecting and sending the {@link Chunk}s 
   * from the global {@link ChunkQueue} which where added by {@link Adaptors}. We want to separate
   * the long living (i.e. looping) behavior from the ConnectorClient because we also want to be able
   * to use the HttpConnectorClient for its add and send API in arbitrary applications that want to send
   * chunks without an {@link LocalAgent} daemon.
   * 
   * * <p>
   * On error, tries the list of available collectors, pauses for a minute, and then repeats.
   * </p>
   * <p> Will wait forever for collectors to come up. </p>
  
   */
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Timer;
  import java.util.TimerTask;
  import org.apache.hadoop.chukwa.Chunk;
  import org.apache.hadoop.chukwa.datacollection.ChunkQueue;
  import org.apache.hadoop.chukwa.datacollection.DataFactory;
  import org.apache.hadoop.chukwa.datacollection.agent.ChukwaAgent;
  import org.apache.hadoop.chukwa.datacollection.connector.Connector;
  import org.apache.hadoop.chukwa.datacollection.sender.*;
  import org.apache.hadoop.chukwa.util.DaemonWatcher;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.log4j.Logger;
  
  public class HttpConnector implements Connector, Runnable {
  
    static Logger log = Logger.getLogger(HttpConnector.class);
  
    Timer statTimer = null;
    volatile int chunkCount = 0;
    
    int MAX_SIZE_PER_POST = 2 * 1024 * 1024;
    int MIN_POST_INTERVAL = 5 * 1000;
    public static final String MIN_POST_INTERVAL_OPT = "httpConnector.minPostInterval";
    public static final String MAX_SIZE_PER_POST_OPT = "httpConnector.maxPostSize";
    public static final String ASYNC_ACKS_OPT = "httpConnector.asyncAcks";
  
    boolean ASYNC_ACKS = false;
    
    ChunkQueue chunkQueue;
  
    ChukwaAgent agent;
    String argDestination = null;
  
    private volatile boolean stopMe = false;
    private Iterator<String> collectors = null;
    protected ChukwaSender connectorClient = null;
  
    { //instance initializer block
      statTimer = new Timer();
      statTimer.schedule(new TimerTask() {
        public void run() {
          int count = chunkCount;
          chunkCount = 0;
          log.info("# http chunks ACK'ed since last report: " + count);
        }
      }, 100, 60 * 1000);
    }
  
    public HttpConnector(ChukwaAgent agent) {
      this.agent = agent;
    }
  
    public HttpConnector(ChukwaAgent agent, String destination) {
      this.agent = agent;
      this.argDestination = destination;
  
      log.info("Setting HTTP Connector URL manually using arg passed to Agent: "
          + destination);
    }
 
   public void start() {
 
     chunkQueue = DataFactory.getInstance().getEventQueue();
     Configuration conf = agent.getConfiguration();
     MAX_SIZE_PER_POST = conf.getInt(MAX_SIZE_PER_POST_OPT, MAX_SIZE_PER_POST);
     MIN_POST_INTERVAL = conf.getInt(MIN_POST_INTERVAL_OPT, MIN_POST_INTERVAL);
     ASYNC_ACKS = conf.getBoolean(ASYNC_ACKS_OPT, ASYNC_ACKS);
     (new Thread(this, "HTTP post thread")).start();
   }
 
   public void shutdown() {
     stopMe = true;
     connectorClient.stop();
   }
 
   public void run() {
     log.info("HttpConnector started at time:" + System.currentTimeMillis());
 
     // build a list of our destinations from collectors
     try {
       if(collectors == null)
         collectors = DataFactory.getInstance().getCollectorURLs(agent.getConfiguration());
     } catch (IOException e) {
       log.error("Failed to retrieve list of collectors from "
           + "conf/collectors file", e);
     }
     
     if(ASYNC_ACKS) {
       try {
         connectorClient = new AsyncAckSender(agent.getConfiguration(), agent);
       } catch(IOException e) {
         log.fatal("can't read AsycAck hostlist file, exiting");
         agent.shutdown(true);
       }
     } else
       connectorClient = new ChukwaHttpSender(agent.getConfiguration());
 
     if (argDestination != null) {
       ArrayList<String> tmp = new ArrayList<String>();
       tmp.add(argDestination);
       collectors = tmp.iterator();
       log.info("using collector specified at agent runtime: " + argDestination);
     } else
       log.info("using collectors from collectors file");
 
     if (collectors == null || !collectors.hasNext()) {
       log.error("No collectors specified, exiting (and taking agent with us).");
       agent.shutdown(true);// error is unrecoverable, so stop hard.
       return;
     }
 
     connectorClient.setCollectors(collectors);
 
 
     try {
       long lastPost = System.currentTimeMillis();
       while (!stopMe) {
         List<Chunk> newQueue = new ArrayList<Chunk>();
         try {
           // get all ready chunks from the chunkQueue to be sent
           chunkQueue.collect(newQueue, MAX_SIZE_PER_POST); // FIXME: should
                                                            // really do this by size
 
         } catch (InterruptedException e) {
           System.out.println("thread interrupted during addChunks(ChunkQueue)");
           Thread.currentThread().interrupt();
           break;
         }
         List<ChukwaHttpSender.CommitListEntry> results = connectorClient
             .send(newQueue);
         // checkpoint the chunks which were committed
         for (ChukwaHttpSender.CommitListEntry cle : results) {
           agent.reportCommit(cle.adaptor, cle.uuid);
           chunkCount++;
         }
 
         long now = System.currentTimeMillis();
         long delta = MIN_POST_INTERVAL - now + lastPost;
         if(delta > 0) {
           Thread.sleep(delta); // wait for stuff to accumulate
         }
         lastPost = now;
       } // end of try forever loop
       log.info("received stop() command so exiting run() loop to shutdown connector");
     } catch (OutOfMemoryError e) {
       log.warn("Bailing out", e);
       DaemonWatcher.bailout(-1);
     } catch (InterruptedException e) {
       // do nothing, let thread die.
       log.warn("Bailing out", e);
       DaemonWatcher.bailout(-1);
     } catch (java.io.IOException e) {
       log.error("connector failed; shutting down agent");
       agent.shutdown(true);
     }
   }
 
   @Override
   public void reloadConfiguration() {
     Iterator<String> destinations = null;
 
     // build a list of our destinations from collectors
     try {
       destinations = DataFactory.getInstance().getCollectorURLs(agent.getConfiguration());
     } catch (IOException e) {
       log.error("Failed to retreive list of collectors from conf/collectors file", e);
     }
     if (destinations != null && destinations.hasNext()) {
       collectors = destinations;
       connectorClient.setCollectors(collectors);
       log.info("Resetting collectors");
     }
   }
   
   public ChukwaSender getSender() {
     return connectorClient;
   }
   
   public void setCollectors(Iterator<String> list) {
     collectors = list;
   }
 }