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/*
 * Copyright © 2017 camunda services GmbH ([email protected])
 *
 * Licensed 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 io.zeebe.gossip.protocol;

import io.zeebe.clustering.gossip.GossipEventDecoder;
import io.zeebe.clustering.gossip.GossipEventType;
import io.zeebe.clustering.gossip.MessageHeaderDecoder;
import io.zeebe.gossip.Loggers;
import io.zeebe.transport.RemoteAddress;
import io.zeebe.transport.ServerOutput;
import io.zeebe.transport.ServerRequestHandler;
import java.util.EnumMap;
import java.util.Map;
import org.agrona.DirectBuffer;
import org.slf4j.Logger;

public class GossipRequestHandler implements ServerRequestHandler {
  private static final Logger LOG = Loggers.GOSSIP_LOGGER;

  private final MessageHeaderDecoder headerDecoder = new MessageHeaderDecoder();

  private final GossipEvent gossipEvent;

  private final Map consumers =
      new EnumMap<>(GossipEventType.class);

  public GossipRequestHandler(GossipEventFactory eventFactory) {
    this.gossipEvent = eventFactory.createFailureDetectionEvent();
  }

  public void registerGossipEventConsumer(GossipEventType eventType, GossipEventConsumer consumer) {
    consumers.put(eventType, consumer);
  }

  @Override
  public boolean onRequest(
      ServerOutput output,
      RemoteAddress remoteAddress,
      DirectBuffer buffer,
      int offset,
      int length,
      long requestId) {
    headerDecoder.wrap(buffer, offset);

    final int schemaId = headerDecoder.schemaId();
    final int templateId = headerDecoder.templateId();

    if (GossipEventDecoder.SCHEMA_ID == schemaId && GossipEventDecoder.TEMPLATE_ID == templateId) {
      // process the received event (i.e. consumer membership and custom events)
      gossipEvent.wrap(buffer, offset, length);

      final GossipEventType eventType = gossipEvent.getEventType();

      final GossipEventConsumer consumer = consumers.get(eventType);
      if (consumer != null) {
        LOG.trace("Received gossip event {} from node '{}'", eventType, gossipEvent.getSenderId());

        consumer.accept(gossipEvent, requestId, remoteAddress.getStreamId());
      } else {
        LOG.warn("No consumer registered for gossip event type '{}'", eventType);
      }
    }

    return true;
  }
}