/*
 * Copyright 2002-2016 the original author or authors.
 *
 * 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 org.springframework.integration.file;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertNotSame;
import static org.junit.Assert.assertNull;

import java.io.File;
import java.util.concurrent.CountDownLatch;

import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.runner.RunWith;

import org.springframework.beans.DirectFieldAccessor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.Message;
import org.springframework.test.annotation.Repeat;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

/**
 * @author Iwein Fuld
 * @author Gary Russell
 * @author Artem Bilan
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration
public class FileReadingMessageSourceIntegrationTests {

	@Autowired
	FileReadingMessageSource pollableFileSource;

	private static File inputDir;

	@AfterClass
	public static void cleanUp() throws Throwable {
		if (inputDir.exists()) {
			inputDir.delete();
		}
	}

	@BeforeClass
	public static void setupInputDir() {
		inputDir = new File(System.getProperty("java.io.tmpdir") + "/"
				+ FileReadingMessageSourceIntegrationTests.class.getSimpleName());
		inputDir.mkdir();
		clean();
	}

	@AfterClass
	public static void tearDown() {
		clean();
		inputDir.delete();
	}

	private static void clean() {
		File[] files = inputDir.listFiles();
		for (File file : files) {
			file.delete();
		}
	}

	@Before
	public void generateTestFiles() throws Exception {
		File.createTempFile("test", null, inputDir).setLastModified(System.currentTimeMillis() - 1000);
		File.createTempFile("test", null, inputDir).setLastModified(System.currentTimeMillis() - 1000);
		File.createTempFile("test", null, inputDir).setLastModified(System.currentTimeMillis() - 1000);
	}

	@After
	public void cleanupInputDir() throws Exception {
		File[] listFiles = inputDir.listFiles();
		for (int i = 0; i < listFiles.length; i++) {
			listFiles[i].delete();
		}
	}

	@AfterClass
	public static void removeInputDir() throws Exception {
		inputDir.delete();
	}


	@Test
	public void configured() throws Exception {
		DirectFieldAccessor accessor = new DirectFieldAccessor(pollableFileSource);
		assertEquals(inputDir, accessor.getPropertyValue("directory"));
	}

	@Test
	public void getFiles() throws Exception {
		Message<File> received1 = pollableFileSource.receive();
		assertNotNull("This should return the first message", received1);
		Message<File> received2 = pollableFileSource.receive();
		assertNotNull(received2);
		Message<File> received3 = pollableFileSource.receive();
		assertNotNull(received3);
		assertNotSame(received1 + " == " + received2, received1.getPayload(), received2.getPayload());
		assertNotSame(received1 + " == " + received3, received1.getPayload(), received3.getPayload());
		assertNotSame(received2 + " == " + received3, received2.getPayload(), received3.getPayload());
	}

	@Test
	public void parallelRetrieval() throws Exception {
		Message<File> received1 = pollableFileSource.receive();
		Message<File> received2 = pollableFileSource.receive();
		Message<File> received3 = pollableFileSource.receive();
		assertNotSame(received1 + " == " + received2, received1, received2);
		assertNotSame(received1 + " == " + received3, received1, received3);
		assertNotSame(received2 + " == " + received3, received2, received3);
	}

	@Test
	public void inputDirExhausted() throws Exception {
		assertNotNull(pollableFileSource.receive());
		assertNotNull(pollableFileSource.receive());
		Message<File> receive = pollableFileSource.receive();
		assertNotNull(receive);
		File payload = receive.getPayload();
		assertEquals(payload, receive.getHeaders().get(FileHeaders.ORIGINAL_FILE));
		assertEquals(payload.getName(), receive.getHeaders().get(FileHeaders.FILENAME));
		assertEquals(payload.getName(), receive.getHeaders().get(FileHeaders.RELATIVE_PATH));
		assertNull(pollableFileSource.receive());
	}

	@Test
	@Repeat(5)
	public void concurrentProcessing() throws Exception {
		CountDownLatch go = new CountDownLatch(1);
		Runnable successfulConsumer = () -> {
			Message<File> received = pollableFileSource.receive();
			while (received == null) {
				Thread.yield();
				received = pollableFileSource.receive();
			}
		};
		Runnable failingConsumer = () -> {
			Message<File> received = pollableFileSource.receive();
			if (received != null) {
				pollableFileSource.onFailure(received);
			}
		};
		CountDownLatch successfulDone = doConcurrently(3, successfulConsumer, go);
		CountDownLatch failingDone = doConcurrently(10, failingConsumer, go);
		go.countDown();
		try {
			successfulDone.await();
			failingDone.await();
		}
		catch (InterruptedException e) {
			Thread.currentThread().interrupt();
		}
		// make sure three different files were taken
		Message<File> received = pollableFileSource.receive();
		assertNull(received);
	}

	/**
	 * Convenience method to run part of a test concurrently in multiple threads
	 *
	 * @param numberOfThreads how many threads to spawn
	 * @param runnable        the runnable that should be run by all the threads
	 * @param start           the {@link java.util.concurrent.CountDownLatch} instance
	 *                        telling it when to assume everything works
	 * @return a latch that will be counted down once all threads have run their
	 *		 runnable.
	 */
	private CountDownLatch doConcurrently(int numberOfThreads, final Runnable runnable, final CountDownLatch start) {
		final CountDownLatch started = new CountDownLatch(numberOfThreads);
		final CountDownLatch done = new CountDownLatch(numberOfThreads);
		for (int i = 0; i < numberOfThreads; i++) {
			new Thread(new Runnable() {

				@Override
				public void run() {
					started.countDown();
					try {
						started.await();
						start.await();
					}
					catch (InterruptedException e) {
						Thread.currentThread().interrupt();
					}
					runnable.run();
					done.countDown();
				}

			}).start();
		}
		return done;
	}

}