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/*
 * 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.client.deployment;

import org.apache.flink.annotation.Internal;
import org.apache.flink.configuration.Configuration;

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

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Optional;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
import java.util.stream.Collectors;
import java.util.stream.Stream;

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

/** A service provider for {@link ClusterClientFactory cluster client factories}. */
@Internal
public class DefaultClusterClientServiceLoader implements ClusterClientServiceLoader {

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

    @Override
    public  ClusterClientFactory getClusterClientFactory(
            final Configuration configuration) {
        checkNotNull(configuration);

        final ServiceLoader loader =
                ServiceLoader.load(ClusterClientFactory.class);

        final List compatibleFactories = new ArrayList<>();
        final Iterator factories = loader.iterator();
        while (factories.hasNext()) {
            try {
                final ClusterClientFactory factory = factories.next();
                if (factory != null && factory.isCompatibleWith(configuration)) {
                    compatibleFactories.add(factory);
                }
            } catch (Throwable e) {
                if (e.getCause() instanceof NoClassDefFoundError) {
                    LOG.info("Could not load factory due to missing dependencies.");
                } else {
                    throw e;
                }
            }
        }

        if (compatibleFactories.size() > 1) {
            final List configStr =
                    configuration.toMap().entrySet().stream()
                            .map(e -> e.getKey() + "=" + e.getValue())
                            .collect(Collectors.toList());

            throw new IllegalStateException(
                    "Multiple compatible client factories found for:\n"
                            + String.join("\n", configStr)
                            + ".");
        }

        if (compatibleFactories.isEmpty()) {
            throw new IllegalStateException(
                    "No ClusterClientFactory found. If you were targeting a Yarn cluster, "
                            + "please make sure to export the HADOOP_CLASSPATH environment variable or have hadoop in your "
                            + "classpath. For more information refer to the \"Deployment\" section of the official "
                            + "Apache Flink documentation.");
        }

        return (ClusterClientFactory) compatibleFactories.get(0);
    }

    @Override
    public Stream getApplicationModeTargetNames() {
        final ServiceLoader loader =
                ServiceLoader.load(ClusterClientFactory.class);

        final List result = new ArrayList<>();

        final Iterator it = loader.iterator();
        while (it.hasNext()) {
            try {
                final ClusterClientFactory clientFactory = it.next();

                final Optional applicationName = clientFactory.getApplicationTargetName();
                if (applicationName.isPresent()) {
                    result.add(applicationName.get());
                }

            } catch (ServiceConfigurationError e) {
                // cannot be loaded, most likely because Hadoop is not
                // in the classpath, we can ignore it for now.
            }
        }
        return result.stream();
    }
}