// Copyright (C) 2019 The Android Open Source Project
//
// 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 com.gerritforge.gerrit.eventbroker;

import static com.gerritforge.gerrit.eventbroker.TopicSubscriber.topicSubscriber;
import static com.gerritforge.gerrit.eventbroker.TopicSubscriberWithGroupId.topicSubscriberWithGroupId;

import com.google.common.collect.ImmutableSet;
import com.google.common.flogger.FluentLogger;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.gerrit.common.Nullable;
import com.google.gerrit.server.events.Event;
import java.util.HashSet;
import java.util.Set;
import java.util.function.Consumer;
import java.util.stream.Collectors;

public class InProcessBrokerApi implements BrokerApi {
  private static final FluentLogger log = FluentLogger.forEnclosingClass();
  private final Set<TopicSubscriber> topicSubscribers;
  private final Set<TopicSubscriberWithGroupId> topicSubscribersWithGroupId;

  public InProcessBrokerApi() {
    this.topicSubscribers = new HashSet<>();
    this.topicSubscribersWithGroupId = new HashSet<>();
  }

  @Override
  public ListenableFuture<Boolean> send(String topic, Event message) {
    return unsupported();
  }

  @Override
  public void receiveAsync(String topic, Consumer<Event> eventConsumer) {
    topicSubscribers.add(topicSubscriber(topic, eventConsumer));
  }

  @Override
  public void receiveAsync(String topic, String groupId, Consumer<Event> eventConsumer) {
    topicSubscribersWithGroupId.add(
        topicSubscriberWithGroupId(groupId, topicSubscriber(topic, eventConsumer)));
  }

  @Override
  public Set<TopicSubscriber> topicSubscribers() {
    return ImmutableSet.copyOf(topicSubscribers);
  }

  @Override
  public Set<TopicSubscriberWithGroupId> topicSubscribersWithGroupId() {
    return ImmutableSet.copyOf(topicSubscribersWithGroupId);
  }

  @Override
  public void disconnect() {
    this.topicSubscribers.clear();
    this.topicSubscribersWithGroupId.clear();
  }

  @Override
  public void disconnect(String topic, @Nullable String groupId) {
    Set<TopicSubscriber> topicsToRemove =
        topicSubscribers.stream()
            .filter(ts -> topic.equals(ts.topic()))
            .collect(Collectors.toSet());
    topicSubscribers.removeAll(topicsToRemove);

    Set<TopicSubscriberWithGroupId> topicsWithGroupIdToRemove =
        topicSubscribersWithGroupId.stream()
            .filter(
                tsg ->
                    topic.equals(tsg.topicSubscriber().topic())
                        && (groupId == null || groupId.equals(tsg.groupId())))
            .collect(Collectors.toSet());
    topicSubscribersWithGroupId.removeAll(topicsWithGroupIdToRemove);
  }

  @Override
  public void replayAllEvents(String topic) {
    unsupported();
  }

  private <T> T unsupported() {
    throw new UnsupportedOperationException(
        "InProcessBrokerApi is not intended to be used as a real broker");
  }
}