/**
    * 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.procedure2.store.wal;
  
  import java.io.IOException;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.fs.FSDataInputStream;
  import org.apache.hadoop.fs.FileStatus;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.procedure2.store.ProcedureStoreTracker;
  import org.apache.hadoop.hbase.protobuf.generated.ProcedureProtos.ProcedureWALHeader;
  import org.apache.hadoop.hbase.protobuf.generated.ProcedureProtos.ProcedureWALTrailer;
  
  /**
   * Describes a WAL File
   */
  @InterfaceAudience.Private
  @InterfaceStability.Evolving
  public class ProcedureWALFile implements Comparable<ProcedureWALFile> {
    private static final Log LOG = LogFactory.getLog(ProcedureWALFile.class);
  
    private ProcedureWALHeader header;
    private FSDataInputStream stream;
    private FileStatus logStatus;
    private FileSystem fs;
    private Path logFile;
    private long startPos;
    private long minProcId;
    private long maxProcId;
  
    public ProcedureWALFile(final FileSystem fs, final FileStatus logStatus) {
      this.fs = fs;
      this.logStatus = logStatus;
      this.logFile = logStatus.getPath();
    }
  
    public ProcedureWALFile(FileSystem fs, Path logFile, ProcedureWALHeader header, long startPos) {
      this.fs = fs;
      this.logFile = logFile;
      this.header = header;
      this.startPos = startPos;
    }
  
    public void open() throws IOException {
      if (stream == null) {
        stream = fs.open(logFile);
      }
  
      if (header == null) {
        header = ProcedureWALFormat.readHeader(stream);
        startPos = stream.getPos();
      } else {
        stream.seek(startPos);
      }
    }
  
    public ProcedureWALTrailer readTrailer() throws IOException {
      try {
        return ProcedureWALFormat.readTrailer(stream, startPos, logStatus.getLen());
      } finally {
        stream.seek(startPos);
      }
    }
  
    public void readTracker(ProcedureStoreTracker tracker) throws IOException {
      ProcedureWALTrailer trailer = readTrailer();
      try {
        stream.seek(trailer.getTrackerPos());
        tracker.readFrom(stream);
      } finally {
        stream.seek(startPos);
      }
    }
  
    public void close() {
      if (stream == null) return;
      try {
        stream.close();
     } catch (IOException e) {
       LOG.warn("unable to close the wal file: " + logFile, e);
     } finally {
       stream = null;
     }
   }
 
   public FSDataInputStream getStream() {
     return stream;
   }
 
   public ProcedureWALHeader getHeader() {
     return header;
   }
 
   public boolean isCompacted() {
     return header.getType() == ProcedureWALFormat.LOG_TYPE_COMPACTED;
   }
 
   public long getLogId() {
     return header.getLogId();
   }
 
   public long getSize() {
     return logStatus.getLen();
   }
 
   public void removeFile() throws IOException {
     close();
     fs.delete(logFile, false);
   }
 
   public void setProcIds(long minId, long maxId) {
     this.minProcId = minId;
     this.maxProcId = maxId;
   }
 
   public long getMinProcId() {
     return minProcId;
   }
 
   public long getMaxProcId() {
     return maxProcId;
   }
 
   @Override
   public int compareTo(final ProcedureWALFile other) {
     long diff = header.getLogId() - other.header.getLogId();
     return (diff < 0) ? -1 : (diff > 0) ? 1 : 0;
   }
 
   @Override
   public boolean equals(Object o) {
     if (this == o) return true;
     if (!(o instanceof ProcedureWALFile)) return false;
     return compareTo((ProcedureWALFile)o) == 0;
   }
 
   @Override
   public int hashCode() {
     return logFile.hashCode();
   }
 
   @Override
   public String toString() {
     return logFile.toString();
   }
 }