/*
    * 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;
  
  
  import java.io.File;
  import java.io.IOException;
  import java.util.Iterator;
  
  import org.apache.hadoop.conf.*;
  import org.apache.hadoop.chukwa.datacollection.agent.MemLimitQueue;
  import org.apache.hadoop.chukwa.datacollection.sender.RetryListOfCollectors;
  import org.apache.log4j.Logger;
  
  public class DataFactory {
    static Logger log = Logger.getLogger(DataFactory.class);
    static final int QUEUE_SIZE_KB = 10 * 1024;
    static final String COLLECTORS_FILENAME = "collectors";
    private static DataFactory dataFactory = null;
    private ChunkQueue chunkQueue = null;
  
    private String defaultTags = "";
    
    static {
      dataFactory = new DataFactory();
    }
  
    private DataFactory() {
    }
  
    public static DataFactory getInstance() {
      return dataFactory;
    }
  
    public synchronized ChunkQueue getEventQueue() {
      if (chunkQueue == null) {
        chunkQueue = new MemLimitQueue(QUEUE_SIZE_KB * 1024);
      }
      return chunkQueue;
    }
  
    public String getDefaultTags() {
      return defaultTags;
    }
    
    public void addDefaultTag(String tag) {
      this.defaultTags += " " + tag.trim();
    }
    
    /**
     * @return empty list if file does not exist
     * @throws IOException on other error
     */
    public Iterator<String> getCollectorURLs(Configuration conf, String filename) throws IOException {
      String chukwaHome = System.getenv("CHUKWA_HOME");
      if (chukwaHome == null) {
        chukwaHome = ".";
      }
  
      if (!chukwaHome.endsWith("/")) {
        chukwaHome = chukwaHome + File.separator;
      }
      log.info("Config - System.getenv(\"CHUKWA_HOME\"): [" + chukwaHome + "]");
  
      String chukwaConf = System.getenv("CHUKWA_CONF_DIR");
      if (chukwaConf == null) {
        chukwaConf = chukwaHome + "conf" + File.separator;
      }
  
      log.info("Config - System.getenv(\"chukwaConf\"): [" + chukwaConf + "]");
  
      log.info("setting up collectors file: " + chukwaConf + File.separator
          + COLLECTORS_FILENAME);
      File collectors = new File(chukwaConf + File.separator + filename);
      try {
        return new RetryListOfCollectors(collectors, conf);
      } catch (java.io.IOException e) {
        log.error("failed to read collectors file: ", e);
        throw e;
      }
    }
    public Iterator<String> getCollectorURLs(Configuration conf) throws IOException {
      return getCollectorURLs(conf, "collectors");
   }
 
 }