/*
 * 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.fs.hdfs;

import org.apache.flink.configuration.Configuration;
import org.apache.flink.core.fs.FSDataInputStream;
import org.apache.flink.core.fs.FSDataOutputStream;
import org.apache.flink.core.fs.FileStatus;
import org.apache.flink.core.fs.FileSystem;
import org.apache.flink.core.fs.Path;
import org.apache.flink.util.TestLogger;

import org.junit.AfterClass;
import org.junit.Test;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.nio.charset.StandardCharsets;

import static junit.framework.TestCase.assertEquals;
import static junit.framework.TestCase.assertFalse;
import static junit.framework.TestCase.assertNotNull;
import static junit.framework.TestCase.assertTrue;
import static org.apache.flink.core.fs.FileSystemTestUtils.checkPathEventualExistence;

/**
 * Abstract integration test class for implementations of hadoop file system.
 */
public abstract class AbstractHadoopFileSystemITTest extends TestLogger {

	protected static FileSystem fs;
	protected static Path basePath;
	protected static long deadline;

	public static void checkPathExistence(Path path,
			boolean expectedExists,
			long deadline) throws IOException, InterruptedException {
		if (deadline == 0) {
			//strongly consistency
			assertEquals(expectedExists, fs.exists(path));
		} else {
			//eventually consistency
			checkPathEventualExistence(fs, path, expectedExists, deadline);
		}
	}

	protected void checkEmptyDirectory(Path path) throws IOException, InterruptedException {
		checkPathExistence(path, true, deadline);
	}

	@Test
	public void testSimpleFileWriteAndRead() throws Exception {
		final String testLine = "Hello Upload!";

		final Path path = new Path(basePath, "test.txt");

		try {
			try (FSDataOutputStream out = fs.create(path, FileSystem.WriteMode.OVERWRITE);
				OutputStreamWriter writer = new OutputStreamWriter(out, StandardCharsets.UTF_8)) {
				writer.write(testLine);
			}

			// just in case, wait for the path to exist
			checkPathExistence(path, true, deadline);

			try (FSDataInputStream in = fs.open(path);
				InputStreamReader ir = new InputStreamReader(in, StandardCharsets.UTF_8);
				BufferedReader reader = new BufferedReader(ir)) {
				String line = reader.readLine();
				assertEquals(testLine, line);
			}
		}
		finally {
			fs.delete(path, false);
		}

		checkPathExistence(path, false, deadline);
	}

	@Test
	public void testDirectoryListing() throws Exception {
		final Path directory = new Path(basePath, "testdir/");

		// directory must not yet exist
		assertFalse(fs.exists(directory));

		try {
			// create directory
			assertTrue(fs.mkdirs(directory));

			checkEmptyDirectory(directory);

			// directory empty
			assertEquals(0, fs.listStatus(directory).length);

			// create some files
			final int numFiles = 3;
			for (int i = 0; i < numFiles; i++) {
				Path file = new Path(directory, "/file-" + i);
				try (FSDataOutputStream out = fs.create(file, FileSystem.WriteMode.OVERWRITE);
					OutputStreamWriter writer = new OutputStreamWriter(out, StandardCharsets.UTF_8)) {
					writer.write("hello-" + i + "\n");
				}
				// just in case, wait for the file to exist (should then also be reflected in the
				// directory's file list below)
				checkPathExistence(file, true, deadline);
			}

			FileStatus[] files = fs.listStatus(directory);
			assertNotNull(files);
			assertEquals(3, files.length);

			for (FileStatus status : files) {
				assertFalse(status.isDir());
			}

			// now that there are files, the directory must exist
			assertTrue(fs.exists(directory));
		}
		finally {
			// clean up
			fs.delete(directory, true);
		}

		// now directory must be gone
		checkPathExistence(directory, false, deadline);
	}

	@AfterClass
	public static void teardown() throws IOException, InterruptedException {
		try {
			if (fs != null) {
				// clean up
				fs.delete(basePath, true);

				// now directory must be gone
				checkPathExistence(basePath, false, deadline);
			}
		}
		finally {
			FileSystem.initialize(new Configuration());
		}
	}
}