/*
 * 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.modules.session.internal.filter.attributes;

import org.apache.geode.DataSerializable;
import org.apache.geode.DataSerializer;
import org.apache.geode.internal.util.BlobHelper;
import org.apache.geode.modules.session.internal.filter.GemfireHttpSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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

/**
 * Capture the update to a particular name
 */
public class DeltaEvent implements DataSerializable {

  private static final Logger LOG = LoggerFactory.getLogger(DeltaEvent.class.getName());
  /**
   * The event is either an update (true) or a remove (false)
   */
  private boolean update;

  private String name;

  private Object value = null;

  private GemfireHttpSession session = null;

  /**
   * Constructor for de-serialization only
   */
  public DeltaEvent() {}

  /**
   * Constructor which creates a 'deferred' event. This is used when the value should only be
   * applied when the object is serialized.
   *
   * @param session the session from which the value ultimately will be retrieved
   * @param attribute the name of the attribute
   */
  public DeltaEvent(GemfireHttpSession session, String attribute) {
    this.session = session;
    this.name = attribute;
    this.update = true;
  }

  public DeltaEvent(boolean update, String attribute, Object value) {
    this.update = update;
    this.name = attribute;
    this.value = value;
    blobifyValue();
  }

  private void blobifyValue() {
    if (value instanceof byte[]) {
      LOG.warn("Session attribute is already a byte[] - problems may "
          + "occur transmitting this delta.");
    }
    try {
      value = BlobHelper.serializeToBlob(value);
    } catch (IOException iox) {
      LOG.error("Attribute '" + name + "' value: " + value
          + " cannot be serialized due to the following exception", iox);
    }
  }

  public boolean isUpdate() {
    return update;
  }

  public String getName() {
    return name;
  }

  public Object getValue() {
    return value;
  }

  @Override
  public void toData(DataOutput out) throws IOException {
    if (session != null) {
      value = session.getNativeSession().getAttribute(name);
      blobifyValue();
    }
    out.writeBoolean(update);
    DataSerializer.writeString(name, out);
    DataSerializer.writeObject(value, out);
  }

  @Override
  public void fromData(DataInput in) throws IOException, ClassNotFoundException {
    update = in.readBoolean();
    name = DataSerializer.readString(in);
    value = DataSerializer.readObject(in);
  }
}