/*
 * 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.flink.runtime.highavailability.nonha.embedded;

import org.apache.flink.api.common.JobID;
import org.apache.flink.runtime.highavailability.HighAvailabilityServices;
import org.apache.flink.runtime.highavailability.nonha.AbstractNonHaServices;
import org.apache.flink.runtime.leaderelection.LeaderElectionService;
import org.apache.flink.runtime.leaderretrieval.LeaderRetrievalService;
import org.apache.flink.util.Preconditions;

import javax.annotation.concurrent.GuardedBy;
import java.util.HashMap;
import java.util.concurrent.Executor;

import static org.apache.flink.util.Preconditions.checkNotNull;

/**
 * An implementation of the {@link HighAvailabilityServices} for the non-high-availability case
 * where all participants (ResourceManager, JobManagers, TaskManagers) run in the same process.
 *
 * <p>This implementation has no dependencies on any external services. It returns a fix
 * pre-configured ResourceManager, and stores checkpoints and metadata simply on the heap or
 * on a local file system and therefore in a storage without guarantees.
 */
public class EmbeddedHaServices extends AbstractNonHaServices {

	private final Executor executor;

	private final EmbeddedLeaderService resourceManagerLeaderService;

	private final HashMap<JobID, EmbeddedLeaderService> jobManagerLeaderServices;

	public EmbeddedHaServices(Executor executor) {
		this.executor = Preconditions.checkNotNull(executor);
		this.resourceManagerLeaderService = new EmbeddedLeaderService(executor);
		this.jobManagerLeaderServices = new HashMap<>();
	}

	// ------------------------------------------------------------------------
	//  services
	// ------------------------------------------------------------------------

	@Override
	public LeaderRetrievalService getResourceManagerLeaderRetriever() {
		return resourceManagerLeaderService.createLeaderRetrievalService();
	}

	@Override
	public LeaderElectionService getResourceManagerLeaderElectionService() {
		return resourceManagerLeaderService.createLeaderElectionService();
	}

	@Override
	public LeaderRetrievalService getJobManagerLeaderRetriever(JobID jobID) {
		checkNotNull(jobID);

		synchronized (lock) {
			checkNotShutdown();
			EmbeddedLeaderService service = getOrCreateJobManagerService(jobID);
			return service.createLeaderRetrievalService();
		}
	}

	@Override
	public LeaderElectionService getJobManagerLeaderElectionService(JobID jobID) {
		checkNotNull(jobID);

		synchronized (lock) {
			checkNotShutdown();
			EmbeddedLeaderService service = getOrCreateJobManagerService(jobID);
			return service.createLeaderElectionService();
		}
	}

	// ------------------------------------------------------------------------
	// internal
	// ------------------------------------------------------------------------

	@GuardedBy("lock")
	private EmbeddedLeaderService getOrCreateJobManagerService(JobID jobID) {
		EmbeddedLeaderService service = jobManagerLeaderServices.get(jobID);
		if (service == null) {
			service = new EmbeddedLeaderService(executor);
			jobManagerLeaderServices.put(jobID, service);
		}
		return service;
	}

	// ------------------------------------------------------------------------
	//  shutdown
	// ------------------------------------------------------------------------

	@Override
	public void close() throws Exception {
		synchronized (lock) {
			if (!isShutDown()) {
				// stop all job manager leader services
				for (EmbeddedLeaderService service : jobManagerLeaderServices.values()) {
					service.shutdown();
				}
				jobManagerLeaderServices.clear();

				resourceManagerLeaderService.shutdown();
			}

			super.close();
		}
	}
}