/**
    * Copyright (c) 2011, University of Konstanz, Distributed Systems Group
    * All rights reserved.
    * 
    * Redistribution and use in source and binary forms, with or without
    * modification, are permitted provided that the following conditions are met:
    * * Redistributions of source code must retain the above copyright
    * notice, this list of conditions and the following disclaimer.
    * * Redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution.
   * * Neither the name of the University of Konstanz nor the
   * names of its contributors may be used to endorse or promote products
   * derived from this software without specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
   * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package org.treetank.io;
  
  import static com.google.common.base.Objects.toStringHelper;
  
  import java.io.DataInput;
  import java.io.DataInputStream;
  import java.io.DataOutput;
  import java.io.DataOutputStream;
  import java.io.IOException;
  
  import org.treetank.api.IMetaEntryFactory;
  import org.treetank.api.IDataFactory;
  import org.treetank.bucket.DataBucket;
  import org.treetank.bucket.BucketFactory;
  import org.treetank.bucket.interfaces.IBucket;
  import org.treetank.exception.TTIOException;
  
  import com.sleepycat.bind.tuple.TupleBinding;
  import com.sleepycat.bind.tuple.TupleInput;
  import com.sleepycat.bind.tuple.TupleOutput;
  
  /**
   * <h1>LogValue</h1> 
   * 
   * This class acts as a container for revisioned {@link DataBucket}s. Each
   * {@link DataBucket} is stored in a versioned manner. If
   * modifications occur, the versioned {@link DataBucket}s are dereferenced and
   * reconstructed. Afterwards, this container is used to store a complete {@link DataBucket} as well as one for
   * upcoming modifications.
   * 
   * Both {@link DataBucket}s can differ since the complete one is mainly used for
   * read access and the modifying one for write access (and therefore mostly lazy
   * dereferenced).
   * 
   * Since objects of this class are stored in a cache, the class has to be
   * serializable.
   * 
   * @author Sebastian Graf, University of Konstanz
   * 
   */
  public final class LogValue {
  
      private final IBucket mComplete;
  
      private final IBucket mModified;
  
      /**
       * Constructor with both, complete and modifying bucket.
       * 
       * @param pComplete
       *            to be used as a base for this container
       * @param pModifying
       *            to be used as a base for this container
       */
      public LogValue(final IBucket pComplete, final IBucket pModifying) {
          this.mComplete = pComplete;
          this.mModified = pModifying;
      }
  
      /**
       * Getting the complete bucket.
       * 
       * @return the complete bucket
       */
      public IBucket getComplete() {
          return mComplete;
      }
  
      /**
       * Getting the modified bucket.
       * 
       * @return the modified bucket
      */
     public IBucket getModified() {
         return mModified;
     }
 
  
     /**
      * {@inheritDoc}
      */
     @Override
     public String toString() {
         return toStringHelper(this).add("mComplete", mComplete).add("mModified", mModified).toString();
     }
 
     /**
      * Binding for serializing LogValues in the BDB.
      * 
      * @author Sebastian Graf, University of Konstanz
      * 
      */
     static class LogValueBinding extends TupleBinding<LogValue> {
 
         private final BucketFactory mFac;
 
         /**
          * Constructor
          * 
          * @param pDataFac
          *            for the deserialization of datas
          * @param pMetaFac
          *            for the deserialization of meta-entries
          */
         public LogValueBinding(final IDataFactory pDataFac, final IMetaEntryFactory pMetaFac) {
             mFac = new BucketFactory(pDataFac, pMetaFac);
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public LogValue entryToObject(final TupleInput arg0) {
             try {
                 final DataInput data = new DataInputStream(arg0);
                 final IBucket current = mFac.deserializeBucket(data);
                 final IBucket modified = mFac.deserializeBucket(data);
                 arg0.close();
                 return new LogValue(current, modified);
             } catch (IOException | TTIOException exc) {
                 throw new RuntimeException(exc);
             }
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public void objectToEntry(final LogValue arg0, final TupleOutput arg1) {
             try {
                 final DataOutput data = new DataOutputStream(arg1);
                 arg0.getComplete().serialize(data);
                 arg0.getModified().serialize(data);
                 arg1.close();
             } catch (IOException | TTIOException exc) {
                 throw new RuntimeException(exc);
             }
         }
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public int hashCode() {
         final int prime = 80309;
         int result = 1;
         result = prime * result + ((mComplete == null) ? 0 : mComplete.hashCode());
         result = prime * result + ((mModified == null) ? 0 : mModified.hashCode());
         return result;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean equals(Object obj) {
         if (this == obj)
             return true;
         if (obj == null)
             return false;
         if (getClass() != obj.getClass())
             return false;
         LogValue other = (LogValue)obj;
         if (mComplete == null) {
             if (other.mComplete != null)
                 return false;
         } else if (!mComplete.equals(other.mComplete))
             return false;
         if (mModified == null) {
             if (other.mModified != null)
                 return false;
         } else if (!mModified.equals(other.mModified))
             return false;
         return true;
     }
 }