/*
 * Copyright 2016-present Open Networking Laboratory
 *
 * 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.onosproject.store.primitives.resources.impl;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import io.atomix.Atomix;
import io.atomix.AtomixClient;
import io.atomix.resource.ResourceType;

import java.time.Duration;
import java.util.Arrays;
import java.util.UUID;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;
import org.onlab.util.Tools;
import org.onosproject.store.service.Task;
import org.onosproject.store.service.WorkQueueStats;

import com.google.common.util.concurrent.Uninterruptibles;

/**
 * Unit tests for {@link AtomixWorkQueue}.
 */
public class AtomixWorkQueueTest extends AtomixTestBase {

    private static final Duration DEFAULT_PROCESSING_TIME = Duration.ofMillis(100);
    private static final byte[] DEFAULT_PAYLOAD = "hello world".getBytes();

    @BeforeClass
    public static void preTestSetup() throws Throwable {
        createCopycatServers(1);
    }

    @AfterClass
    public static void postTestCleanup() throws Exception {
        clearTests();
    }

    @Override
    protected ResourceType resourceType() {
        return new ResourceType(AtomixWorkQueue.class);
    }

    @Test
    public void testAdd() throws Throwable {
        String queueName = UUID.randomUUID().toString();
        Atomix atomix1 = createAtomixClient();
        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
        byte[] item = DEFAULT_PAYLOAD;
        queue1.addOne(item).join();

        Atomix atomix2 = createAtomixClient();
        AtomixWorkQueue queue2 = atomix2.getResource(queueName, AtomixWorkQueue.class).join();
        byte[] task2 = DEFAULT_PAYLOAD;
        queue2.addOne(task2).join();

        WorkQueueStats stats = queue1.stats().join();
        assertEquals(stats.totalPending(), 2);
        assertEquals(stats.totalInProgress(), 0);
        assertEquals(stats.totalCompleted(), 0);
    }

    @Test
    public void testAddMultiple() throws Throwable {
        String queueName = UUID.randomUUID().toString();
        Atomix atomix1 = createAtomixClient();
        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
        byte[] item1 = DEFAULT_PAYLOAD;
        byte[] item2 = DEFAULT_PAYLOAD;
        queue1.addMultiple(Arrays.asList(item1, item2)).join();

        WorkQueueStats stats = queue1.stats().join();
        assertEquals(stats.totalPending(), 2);
        assertEquals(stats.totalInProgress(), 0);
        assertEquals(stats.totalCompleted(), 0);
    }

    @Test
    public void testTakeAndComplete() throws Throwable {
        String queueName = UUID.randomUUID().toString();
        Atomix atomix1 = createAtomixClient();
        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
        byte[] item1 = DEFAULT_PAYLOAD;
        queue1.addOne(item1).join();

        Atomix atomix2 = createAtomixClient();
        AtomixWorkQueue queue2 = atomix2.getResource(queueName, AtomixWorkQueue.class).join();
        Task<byte[]> removedTask = queue2.take().join();

        WorkQueueStats stats = queue2.stats().join();
        assertEquals(stats.totalPending(), 0);
        assertEquals(stats.totalInProgress(), 1);
        assertEquals(stats.totalCompleted(), 0);

        assertTrue(Arrays.equals(removedTask.payload(), item1));
        queue2.complete(Arrays.asList(removedTask.taskId())).join();

        stats = queue1.stats().join();
        assertEquals(stats.totalPending(), 0);
        assertEquals(stats.totalInProgress(), 0);
        assertEquals(stats.totalCompleted(), 1);

        // Another take should return null
        assertNull(queue2.take().join());
    }

    @Test
    public void testUnexpectedClientClose() throws Throwable {
        String queueName = UUID.randomUUID().toString();
        Atomix atomix1 = createAtomixClient();
        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
        byte[] item1 = DEFAULT_PAYLOAD;
        queue1.addOne(item1).join();

        AtomixClient atomix2 = createAtomixClient();
        AtomixWorkQueue queue2 = atomix2.getResource(queueName, AtomixWorkQueue.class).join();
        queue2.take().join();

        WorkQueueStats stats = queue1.stats().join();
        assertEquals(0, stats.totalPending());
        assertEquals(1, stats.totalInProgress());
        assertEquals(0, stats.totalCompleted());

        atomix2.close().join();

        stats = queue1.stats().join();
        assertEquals(1, stats.totalPending());
        assertEquals(0, stats.totalInProgress());
        assertEquals(0, stats.totalCompleted());
    }

    @Test
    public void testAutomaticTaskProcessing() throws Throwable {
        String queueName = UUID.randomUUID().toString();
        Atomix atomix1 = createAtomixClient();
        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
        Executor executor = Executors.newSingleThreadExecutor();

        CountDownLatch latch1 = new CountDownLatch(1);
        queue1.registerTaskProcessor(s -> latch1.countDown(), 2, executor);

        AtomixClient atomix2 = createAtomixClient();
        AtomixWorkQueue queue2 = atomix2.getResource(queueName, AtomixWorkQueue.class).join();
        byte[] item1 = DEFAULT_PAYLOAD;
        queue2.addOne(item1).join();

        assertTrue(Uninterruptibles.awaitUninterruptibly(latch1, 5000, TimeUnit.MILLISECONDS));
        queue1.stopProcessing();

        byte[] item2 = DEFAULT_PAYLOAD;
        byte[] item3 = DEFAULT_PAYLOAD;

        Tools.delay((int) DEFAULT_PROCESSING_TIME.toMillis());

        queue2.addMultiple(Arrays.asList(item2, item3)).join();

        WorkQueueStats stats = queue1.stats().join();
        assertEquals(2, stats.totalPending());
        assertEquals(0, stats.totalInProgress());
        assertEquals(1, stats.totalCompleted());

        CountDownLatch latch2 = new CountDownLatch(2);
        queue1.registerTaskProcessor(s -> latch2.countDown(), 2, executor);

        Uninterruptibles.awaitUninterruptibly(latch2, 500, TimeUnit.MILLISECONDS);
    }

    @Test
    public void testDestroy() {
        String queueName = UUID.randomUUID().toString();
        Atomix atomix1 = createAtomixClient();
        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
        byte[] item = DEFAULT_PAYLOAD;
        queue1.addOne(item).join();

        Atomix atomix2 = createAtomixClient();
        AtomixWorkQueue queue2 = atomix2.getResource(queueName, AtomixWorkQueue.class).join();
        byte[] task2 = DEFAULT_PAYLOAD;
        queue2.addOne(task2).join();

        WorkQueueStats stats = queue1.stats().join();
        assertEquals(stats.totalPending(), 2);
        assertEquals(stats.totalInProgress(), 0);
        assertEquals(stats.totalCompleted(), 0);

        queue2.destroy().join();

        stats = queue1.stats().join();
        assertEquals(stats.totalPending(), 0);
        assertEquals(stats.totalInProgress(), 0);
        assertEquals(stats.totalCompleted(), 0);
    }

    @Test
    public void testCompleteAttemptWithIncorrectSession() {
        String queueName = UUID.randomUUID().toString();
        Atomix atomix1 = createAtomixClient();
        AtomixWorkQueue queue1 = atomix1.getResource(queueName, AtomixWorkQueue.class).join();
        byte[] item = DEFAULT_PAYLOAD;
        queue1.addOne(item).join();

        Task<byte[]> task = queue1.take().join();
        String taskId = task.taskId();

        // Create another client and get a handle to the same queue.
        Atomix atomix2 = createAtomixClient();
        AtomixWorkQueue queue2 = atomix2.getResource(queueName, AtomixWorkQueue.class).join();

        // Attempt completing the task with new client and verify task is not completed
        queue2.complete(taskId).join();

        WorkQueueStats stats = queue1.stats().join();
        assertEquals(stats.totalPending(), 0);
        assertEquals(stats.totalInProgress(), 1);
        assertEquals(stats.totalCompleted(), 0);
    }
}