/*
 * 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.beam.sdk.io.hdfs;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.fail;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import java.net.URI;
import java.util.ServiceLoader;
import org.apache.beam.sdk.io.FileSystem;
import org.apache.beam.sdk.io.FileSystemRegistrar;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.junit.After;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 * Tests for {@link HadoopFileSystemRegistrar}.
 */
@RunWith(JUnit4.class)
public class HadoopFileSystemRegistrarTest {

  @Rule public TemporaryFolder tmpFolder = new TemporaryFolder();
  private Configuration configuration;
  private MiniDFSCluster hdfsCluster;
  private URI hdfsClusterBaseUri;

  @Before
  public void setUp() throws Exception {
    configuration = new Configuration();
    configuration.set(MiniDFSCluster.HDFS_MINIDFS_BASEDIR, tmpFolder.getRoot().getAbsolutePath());
    MiniDFSCluster.Builder builder = new MiniDFSCluster.Builder(configuration);
    hdfsCluster = builder.build();
    hdfsClusterBaseUri = new URI(configuration.get("fs.defaultFS") + "/");
  }

  @After
  public void tearDown() throws Exception {
    hdfsCluster.shutdown();
  }

  @Test
  public void testServiceLoader() {
    HadoopFileSystemOptions options = PipelineOptionsFactory.as(HadoopFileSystemOptions.class);
    options.setHdfsConfiguration(ImmutableList.of(configuration));
    for (FileSystemRegistrar registrar
        : Lists.newArrayList(ServiceLoader.load(FileSystemRegistrar.class).iterator())) {
      if (registrar instanceof HadoopFileSystemRegistrar) {
        Iterable<FileSystem> fileSystems = registrar.fromOptions(options);
        assertEquals(hdfsClusterBaseUri.getScheme(),
            ((HadoopFileSystem) Iterables.getOnlyElement(fileSystems)).getScheme());
        return;
      }
    }
    fail("Expected to find " + HadoopFileSystemRegistrar.class);
  }
}