/**
 * 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.activemq.store;

import java.io.File;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import org.apache.activemq.broker.LockableServiceSupport;
import org.apache.activemq.broker.Locker;
import org.apache.activemq.util.IOHelper;
import org.apache.activemq.util.LockFile;
import org.apache.activemq.util.ServiceStopper;
import org.apache.activemq.util.Wait;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.appender.AbstractAppender;
import org.apache.logging.log4j.core.config.Configurator;
import org.apache.logging.log4j.core.config.Property;
import org.apache.logging.log4j.core.filter.AbstractFilter;
import org.apache.logging.log4j.core.layout.MessageLayout;
import org.junit.Assert;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;
import org.slf4j.LoggerFactory;


import static org.junit.Assert.assertTrue;

public class SharedFileLockerLoopTest {
    private static final org.slf4j.Logger LOG = LoggerFactory.getLogger(SharedFileLockerLoopTest.class);

    @Rule
    public TemporaryFolder testFolder;


    public SharedFileLockerLoopTest() {
        File file = new File(IOHelper.getDefaultDataDirectory());
        file.mkdir();

        // TemporaryFolder will make sure the files are removed after the test is done
        testFolder = new TemporaryFolder(file);
    }

    @Test
    public void testStopNoStart() throws Exception {
        SharedFileLocker locker1 = new SharedFileLocker();
        locker1.setDirectory(testFolder.getRoot());
        locker1.stop();
    }

    @Test
    public void testLoop() throws Exception {
        // Increase the number of iterations if you are debugging races
        for (int i = 0; i < 100; i++) {
            internalLoop(5);
        }

    }

    private void internalLoop(long timewait) throws Exception {
        final AtomicInteger logCounts = new AtomicInteger(0);
        
     // start new
        final var logger = org.apache.logging.log4j.core.Logger.class.cast(LogManager.getRootLogger());
        final var appender = new AbstractAppender("testAppender", new AbstractFilter() {}, new MessageLayout(), false, new Property[0]) {
            @Override
            public void append(LogEvent event) {
                if (event.getLevel() == Level.INFO) {
                    logCounts.incrementAndGet();
                }
            }
        };
        appender.start();

        Configurator.setRootLevel(Level.DEBUG);
        logger.get().addAppender(appender, Level.DEBUG, new AbstractFilter() {});
        logger.addAppender(appender);

        final AtomicInteger errors = new AtomicInteger(0);

        Thread thread = null;

        SharedFileLocker locker1 = new SharedFileLocker();
        locker1.setDirectory(testFolder.getRoot());

        final SharedFileLocker locker2 = new SharedFileLocker();
        locker2.setLockAcquireSleepInterval(1);
        locker2.setDirectory(testFolder.getRoot());


        try {
            locker1.doStart();

            assertTrue(locker1.keepAlive());

            thread = new Thread("Locker Thread") {
                public void run() {
                    try {
                        locker2.doStart();
                    } catch (Throwable e) {
                        errors.incrementAndGet();
                    }
                }
            };

            thread.start();

            // I need to make sure the info was already logged
            // but I don't want to have an unecessary wait here,
            // as I want the test to run as fast as possible
            {
                long timeout = System.currentTimeMillis() + 5000;
                while (logCounts.get() < 1 && System.currentTimeMillis() < timeout) {
                    Thread.sleep(1);
                }
            }

            if (timewait > 0) {
                Thread.sleep(timewait);
            }

            assertTrue(thread.isAlive());

            locker1.stop();

            // 10 seconds here is an eternity, but it should only take milliseconds
            thread.join(5000);

            Assert.assertEquals("Extra logs in place", 1, logCounts.get());

            long timeout = System.currentTimeMillis() + 5000;

            while (timeout > System.currentTimeMillis() && !locker2.keepAlive()) {
                Thread.sleep(1);
            }

            assertTrue(locker2.keepAlive());

            locker2.stop();

            Assert.assertEquals(0, errors.get());

        } finally {

            logger.removeAppender(appender);

            // to make sure we won't leak threads if the test ever failed for any reason
            thread.join(1000);
            if (thread.isAlive()) {
                thread.interrupt();
            }

            File lockFile = new File(testFolder.getRoot(), "lock");
            lockFile.delete();
        }

    }

    @Test
    public void verifyLockAcquireWaitsForLockDrop() throws Exception {

        final AtomicInteger logCounts = new AtomicInteger(0);
     // start new
        final var logger = org.apache.logging.log4j.core.Logger.class.cast(LogManager.getLogger(SharedFileLocker.class));
        final var appender = new AbstractAppender("testAppender2", new AbstractFilter() {}, new MessageLayout(), false, new Property[0]) {
            @Override
            public void append(LogEvent event) {
                logCounts.incrementAndGet();
            }
        };
        appender.start();

        logger.get().addAppender(appender, Level.DEBUG, new AbstractFilter() {});
        logger.addAppender(appender);

        LockableServiceSupport config = new LockableServiceSupport() {

            @Override
            public long getLockKeepAlivePeriod() {
                return 500;
            }

            @Override
            public Locker createDefaultLocker() throws IOException {
                return null;
            }

            public void init() throws Exception {
            }

            protected void doStop(ServiceStopper stopper) throws Exception {
            }

            protected void doStart() throws Exception {
            }
        };

        final SharedFileLocker underTest = new SharedFileLocker();
        underTest.setDirectory(testFolder.getRoot());
        underTest.setLockAcquireSleepInterval(5);
        underTest.setLockable(config);

        // get the in jvm lock
        File lockFile = new File(testFolder.getRoot(), "lock");
        String jvmProp = LockFile.class.getName() + ".lock." + lockFile.getCanonicalPath();
        System.getProperties().put(jvmProp, jvmProp);

        final CountDownLatch locked = new CountDownLatch(1);
        ExecutorService executorService = Executors.newSingleThreadExecutor();
        try {
            final AtomicLong acquireTime = new AtomicLong(0l);
            executorService.execute(new Runnable() {
                @Override
                public void run() {
                    try {
                        underTest.start();
                        acquireTime.set(System.currentTimeMillis());
                        locked.countDown();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            });

            assertTrue("locker failed to obtain lock", Wait.waitFor(new Wait.Condition() {
                @Override
                public boolean isSatisified() throws Exception {
                    return logCounts.get() > 0;
                }
            }, 5000, 10));

            // release vm lock
            long releaseTime = System.currentTimeMillis();
            System.getProperties().remove(jvmProp);

            assertTrue("locker got lock", locked.await(5, TimeUnit.SECONDS));

            // verify delay in start
            LOG.info("ReleaseTime: " + releaseTime + ", AcquireTime:" + acquireTime.get());
            assertTrue("acquire delayed for keepAlive: " + config.getLockKeepAlivePeriod(), acquireTime.get() >= releaseTime + config.getLockKeepAlivePeriod());

        } finally {
            executorService.shutdownNow();
            underTest.stop();
            lockFile.delete();
            logger.removeAppender(appender);
        }
    }
}
