/**
 * Copyright 2010 The Apache Software Foundation
 *
 * 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.regionserver.wal;

import java.io.IOException;
import java.util.LinkedList;
import java.util.Queue;

import org.apache.hadoop.hbase.regionserver.wal.HLog.Entry;

public class FaultySequenceFileLogReader extends SequenceFileLogReader {

  enum FailureType {
    BEGINNING, MIDDLE, END, NONE
  }

  Queue<Entry> nextQueue = new LinkedList<Entry>();
  int numberOfFileEntries = 0;

  FailureType getFailureType() {
    return FailureType.valueOf(conf.get("faultysequencefilelogreader.failuretype", "NONE"));
  }

  @Override
  public HLog.Entry next(HLog.Entry reuse) throws IOException {
    this.entryStart = this.reader.getPosition();
    boolean b = true;

    if (nextQueue.isEmpty()) { // Read the whole thing at once and fake reading
      while (b == true) {
        HLogKey key = HLog.newKey(conf);
        WALEdit val = new WALEdit();
        HLog.Entry e = new HLog.Entry(key, val);
        b = this.reader.next(e.getKey(), e.getEdit());
        nextQueue.offer(e);
        numberOfFileEntries++;
      }
    }

    if (nextQueue.size() == this.numberOfFileEntries
        && getFailureType() == FailureType.BEGINNING) {
      throw this.addFileInfoToException(new IOException("fake Exception"));
    } else if (nextQueue.size() == this.numberOfFileEntries / 2
        && getFailureType() == FailureType.MIDDLE) {
      throw this.addFileInfoToException(new IOException("fake Exception"));
    } else if (nextQueue.size() == 1 && getFailureType() == FailureType.END) {
      throw this.addFileInfoToException(new IOException("fake Exception"));
    }

    if (nextQueue.peek() != null) {
      edit++;
    }

    Entry e = nextQueue.poll();

    if (e.getEdit().isEmpty()) {
      return null;
    }
    return e;
  }
}