/*
 * 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.geode.internal.cache.compression;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.geode.DataSerializer;
import org.apache.geode.cache.Region;
import org.apache.geode.compression.Compressor;
import org.apache.geode.internal.InternalDataSerializer;
import org.apache.geode.internal.cache.BytesAndBitsForCompactor;
import org.apache.geode.internal.cache.CachedDeserializable;
import org.apache.geode.internal.cache.CachedDeserializableFactory;
import org.apache.geode.internal.cache.EntryEventImpl;
import org.apache.geode.internal.cache.RegionEntry;
import org.apache.geode.internal.lang.StringUtils;
import org.apache.geode.internal.serialization.DataSerializableFixedID;
import org.apache.geode.internal.serialization.DeserializationContext;
import org.apache.geode.internal.serialization.SerializationContext;
import org.apache.geode.internal.size.Sizeable;

/**
 * An abstract implementation of {@link CachedDeserializable} that prefers serialization and
 * compresses the internal serialized value.
 *
 */
public abstract class CompressedCachedDeserializable
    implements CachedDeserializable, DataSerializableFixedID {
  /**
   * +PER_OBJECT_OVERHEAD for CompressedCachedDeserializable object +4 for value field
   */
  static final int BASE_MEM_OVERHEAD = PER_OBJECT_OVERHEAD + 4;

  /**
   * Compressed region entry value.
   */
  protected byte[] value = null;

  /**
   * Empty constructor for serialization.
   */
  public CompressedCachedDeserializable() {}

  /**
   * @return A {@link Compressor} for compressing/decompressing the region entry value.
   */
  protected abstract Compressor getCompressor();

  /**
   * @return the memory overhead for this implementation CompressedCachedDeserializable.
   */
  protected abstract int getMemoryOverhead();

  /**
   * @see DataSerializableFixedID#getDSFID()
   */
  @Override
  public abstract int getDSFID();

  /**
   * Creates a new {@link CompressedCachedDeserializable} with a serialized value.
   *
   * @param serializedValue a region entry value that has already been serialized.
   */
  public CompressedCachedDeserializable(final byte[] serializedValue) {
    if (serializedValue == null) {
      throw new NullPointerException(
          "value must not be null");
    }

    this.value = getCompressor().compress(serializedValue);
  }

  /**
   * Creates a new {@link CompressedCachedDeserializable} with an unserialized value.
   *
   * @param obj a region entry value.
   */
  public CompressedCachedDeserializable(final Object obj) {
    if (obj == null)
      throw new NullPointerException(
          "value must not be null");

    this.value = getCompressor().compress(EntryEventImpl.serialize(obj));
  }

  /**
   * @see Sizeable#getSizeInBytes()
   */
  @Override
  public int getSizeInBytes() {
    return getMemoryOverhead() + CachedDeserializableFactory.getByteSize(this.value);
  }

  /**
   * @see DataSerializableFixedID#toData(DataOutput, SerializationContext)
   */
  @Override
  public void toData(DataOutput out,
      SerializationContext context) throws IOException {
    DataSerializer.writeByteArray(getCompressor().decompress(this.value), out);
  }

  /**
   * @see DataSerializableFixedID#fromData(DataInput, DeserializationContext)
   */
  @Override
  public void fromData(DataInput in,
      DeserializationContext context) throws IOException, ClassNotFoundException {
    this.value = getCompressor().compress(DataSerializer.readByteArray(in));
  }

  /**
   * Returns the serialized value of the region entry contained by this
   * CompressedCachedDeserializable. This value is the uncompressed value.
   *
   * @see CachedDeserializable#getSerializedValue()
   */
  @Override
  public byte[] getSerializedValue() {
    return getCompressor().decompress(this.value);
  }

  /**
   * Returns the deserialized value. However, unlike the specification of this method as described
   * in {@link CachedDeserializable#getDeserializedForReading()} this method does not optimize for
   * future calls leaving the value serialized and compressed.
   */
  @Override
  public Object getDeserializedForReading() {
    return getDeserializedValue(null, null);
  }

  /**
   * @see CachedDeserializable#getStringForm()
   */
  @Override
  public String getStringForm() {
    try {
      return StringUtils.forceToString(getDeserializedForReading());
    } catch (RuntimeException ex) {
      return "Could not convert object to string because " + ex;
    }
  }

  /**
   * @see CachedDeserializable#getDeserializedWritableCopy(Region, RegionEntry)
   */
  @Override
  public Object getDeserializedWritableCopy(Region r, RegionEntry re) {
    return getDeserializedValue(r, re);
  }

  /**
   * @see CachedDeserializable#getDeserializedValue(Region, RegionEntry)
   */
  @Override
  public Object getDeserializedValue(Region r, RegionEntry re) {
    return EntryEventImpl.deserialize(getCompressor().decompress(this.value));
  }

  /**
   * @see CachedDeserializable#getValue()
   */
  @Override
  public Object getValue() {
    return getCompressor().decompress(this.value);
  }

  @Override
  public void writeValueAsByteArray(DataOutput out) throws IOException {
    toData(out, InternalDataSerializer.createSerializationContext(out));
  }

  @Override
  public void fillSerializedValue(BytesAndBitsForCompactor wrapper, byte userBits) {
    byte[] uncompressed = getCompressor().decompress(this.value);
    wrapper.setData(uncompressed, userBits, uncompressed.length, false);
  }

  @Override
  public int getValueSizeInBytes() {
    return CachedDeserializableFactory.getByteSize(this.value);
  }
}