/*
    * 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.adaptor.filetailer;
  
  
  import org.apache.hadoop.chukwa.ChunkImpl;
  import org.apache.hadoop.chukwa.datacollection.ChunkReceiver;
  import org.apache.hadoop.chukwa.util.RecordConstants;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  
  /**
   * A subclass of FileTailingAdaptor that reads UTF8/ascii files and splits
   * records at non-escaped carriage returns
   * 
   */
  public class CharFileTailingAdaptorUTF8NewLineEscaped extends
      FileTailingAdaptor {
  
    private static final char SEPARATOR = '\n';
  
    private ArrayList<Integer> offsets = new ArrayList<Integer>();
  
    /**
     * 
     * Note: this method uses a temporary ArrayList (shared across instances).
     * This means we're copying ints each time. This could be a performance issue.
     * Also, 'offsets' never shrinks, and will be of size proportional to the
     * largest number of lines ever seen in an event.
     */
    @Override
    protected int extractRecords(ChunkReceiver eq, long buffOffsetInFile,
        byte[] buf) throws InterruptedException {
      String es = RecordConstants.RECORD_SEPARATOR_ESCAPE_SEQ;
      for (int i = 0; i < buf.length; ++i) {
        // if this is a separator
        if (buf[i] == SEPARATOR) {
          // if possibly preceded by escape sequence (avoid outOfBounds here)
          boolean escaped = false; // was it escaped?
          if (i - es.length() >= 0) {
            escaped = true; // maybe (at least there was room for an escape
                            // sequence, so let's check for the e.s.)
            for (int j = 0; j < es.length(); j++) {
              if (buf[i - es.length() + j] != es.charAt(j)) {
                escaped = false;
              }
            }
          }
          if (!escaped) {
            offsets.add(i);
          }
        }
      }
  
      if (offsets.size() > 0) {
        int[] offsets_i = new int[offsets.size()];
        for (int i = 0; i < offsets.size(); i++) {
          try {
          offsets_i[i] = offsets.get(i);
          } catch(NullPointerException e) {
            // Skip offsets 0 where it can be null.
          }
        }
        // make the stream unique to this adaptor
        int bytesUsed = 0;
        if(buf.length==offsets_i[offsets_i.length -1]) {
          // If Separator is last character of stream,
          // send the record.
          bytesUsed = offsets_i[offsets_i.length - 2] + 1;
        } else {
          // If the last record is partial read,
          // truncate the record to the n -1 new line.
          bytesUsed = offsets_i[offsets_i.length - 1] + 1; // char at last        
        }
                                                             // offset uses a byte
        assert bytesUsed > 0 : " shouldn't send empty events";
        ChunkImpl chunk = new ChunkImpl(type, toWatch.getAbsolutePath(),
            buffOffsetInFile + bytesUsed, Arrays.copyOf(buf, bytesUsed), this);
  
        chunk.setSeqID(buffOffsetInFile + bytesUsed);
        chunk.setRecordOffsets(offsets_i);
        eq.add(chunk);
 
       offsets.clear();
       return bytesUsed;
     } else
       return 0;
   }
 
   public String toString() {
     return "escaped newline CFTA-UTF8";
   }
 
 }