/*
 * 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.DataSerializer;
import org.apache.geode.Delta;
import org.apache.geode.InvalidDeltaException;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This abstract class contains the structures and methods to handle delta updates to attributes.
 */
public abstract class AbstractDeltaSessionAttributes extends AbstractSessionAttributes
    implements Delta {

  private static final Logger LOG =
      LoggerFactory.getLogger(AbstractDeltaSessionAttributes.class.getName());

  /**
   * This map holds the updates to attributes
   */
  protected transient Map<String, DeltaEvent> deltas =
      Collections.synchronizedMap(new HashMap<String, DeltaEvent>());

  @Override
  public boolean hasDelta() {
    return true;
  }

  @Override
  public void toDelta(DataOutput out) throws IOException {
    out.writeInt(maxInactiveInterval);
    out.writeLong(lastAccessedTime);

    synchronized (deltas) {
      DataSerializer.writeInteger(deltas.size(), out);
      for (Map.Entry<String, DeltaEvent> e : deltas.entrySet()) {
        DataSerializer.writeString(e.getKey(), out);
        DataSerializer.writeObject(e.getValue(), out);
      }
      deltas.clear();
    }

    out.writeUTF(jvmOwnerId);
  }

  @Override
  public void fromDelta(DataInput in) throws IOException, InvalidDeltaException {
    maxInactiveInterval = in.readInt();
    lastAccessedTime = in.readLong();
    Map<String, DeltaEvent> localDeltas = new HashMap<String, DeltaEvent>();
    try {
      int size = DataSerializer.readInteger(in);
      for (int i = 0; i < size; i++) {
        String key = DataSerializer.readString(in);
        DeltaEvent evt = DataSerializer.readObject(in);
        localDeltas.put(key, evt);
      }
    } catch (ClassNotFoundException ex) {
      LOG.error("Unable to de-serialize delta events", ex);
      return;
    }

    LOG.debug("Processing {} delta events for {}", localDeltas.size(), session);
    for (DeltaEvent e : localDeltas.values()) {
      if (e.isUpdate()) {
        attributes.put(e.getName(), e.getValue());
        if (session.getNativeSession() != null) {
          session.getNativeSession().setAttribute(e.getName(), e.getValue());
        }
      } else {
        attributes.remove(e.getName());
        if (session.getNativeSession() != null) {
          session.getNativeSession().setAttribute(e.getName(), null);
        }
      }
    }
    jvmOwnerId = in.readUTF();
  }
}