/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the "Elastic License
 * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
 * Public License v 1"; you may not use this file except in compliance with, at
 * your election, the "Elastic License 2.0", the "GNU Affero General Public
 * License v3.0 only", or the "Server Side Public License, v 1".
 */

package org.elasticsearch.threadpool;

import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.util.concurrent.EsExecutors;
import org.elasticsearch.common.util.concurrent.EsThreadPoolExecutor;
import org.elasticsearch.core.TimeValue;
import org.elasticsearch.telemetry.metric.MeterRegistry;
import org.elasticsearch.threadpool.ThreadPool.Names;

import java.lang.reflect.Field;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import static org.hamcrest.CoreMatchers.containsString;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.hasToString;
import static org.hamcrest.Matchers.instanceOf;
import static org.hamcrest.Matchers.is;

public class UpdateThreadPoolSettingsTests extends ESThreadPoolTestCase {

    public void testCorrectThreadPoolTypePermittedInSettings() {
        String threadPoolName = randomThreadPoolName();
        ThreadPool.ThreadPoolType correctThreadPoolType = ThreadPool.THREAD_POOL_TYPES.get(threadPoolName);
        ThreadPool threadPool = null;
        try {
            threadPool = new ThreadPool(
                Settings.builder()
                    .put("node.name", "testCorrectThreadPoolTypePermittedInSettings")
                    .put("thread_pool." + threadPoolName + ".type", correctThreadPoolType.getType())
                    .build(),
                MeterRegistry.NOOP,
                new DefaultBuiltInExecutorBuilders()
            );
            assertEquals(info(threadPool, threadPoolName).getThreadPoolType(), correctThreadPoolType);
        } finally {
            terminateThreadPoolIfNeeded(threadPool);
        }
    }

    public void testWriteThreadPoolsMaxSize() throws InterruptedException {
        final int maxSize = 1 + EsExecutors.allocatedProcessors(Settings.EMPTY);
        final int tooBig = randomIntBetween(1 + maxSize, Integer.MAX_VALUE);

        // try to create a too big thread pool
        final IllegalArgumentException initial = expectThrows(IllegalArgumentException.class, () -> {
            ThreadPool tp = null;
            try {
                tp = new ThreadPool(
                    Settings.builder()
                        .put("node.name", "testIndexingThreadPoolsMaxSize")
                        .put("thread_pool." + Names.WRITE + ".size", tooBig)
                        .build(),
                    MeterRegistry.NOOP,
                    new DefaultBuiltInExecutorBuilders()
                );
            } finally {
                terminateThreadPoolIfNeeded(tp);
            }
        });

        assertThat(
            initial,
            hasToString(
                containsString("Failed to parse value [" + tooBig + "] for setting [thread_pool." + Names.WRITE + ".size] must be ")
            )
        );
    }

    private static int getExpectedThreadPoolSize(Settings settings, String name, int size) {
        if (name.equals(ThreadPool.Names.WRITE) || name.equals(Names.SYSTEM_WRITE) || name.equals(Names.SYSTEM_CRITICAL_WRITE)) {
            return Math.min(size, EsExecutors.allocatedProcessors(settings));
        } else {
            return size;
        }
    }

    public void testFixedExecutorType() throws InterruptedException {
        String threadPoolName = randomThreadPool(ThreadPool.ThreadPoolType.FIXED);
        ThreadPool threadPool = null;

        try {
            int expectedSize = getExpectedThreadPoolSize(Settings.EMPTY, threadPoolName, 15);
            Settings nodeSettings = Settings.builder()
                .put("node.name", "testFixedExecutorType")
                .put("thread_pool." + threadPoolName + ".size", expectedSize)
                .build();
            threadPool = new ThreadPool(nodeSettings, MeterRegistry.NOOP, new DefaultBuiltInExecutorBuilders());
            assertThat(threadPool.executor(threadPoolName), instanceOf(EsThreadPoolExecutor.class));

            assertEquals(info(threadPool, threadPoolName).getThreadPoolType(), ThreadPool.ThreadPoolType.FIXED);
            assertThat(threadPool.executor(threadPoolName), instanceOf(EsThreadPoolExecutor.class));
            assertThat(((EsThreadPoolExecutor) threadPool.executor(threadPoolName)).getCorePoolSize(), equalTo(expectedSize));
            assertThat(((EsThreadPoolExecutor) threadPool.executor(threadPoolName)).getMaximumPoolSize(), equalTo(expectedSize));
            assertThat(info(threadPool, threadPoolName).getMin(), equalTo(expectedSize));
            assertThat(info(threadPool, threadPoolName).getMax(), equalTo(expectedSize));
            // keep alive does not apply to fixed thread pools
            assertThat(((EsThreadPoolExecutor) threadPool.executor(threadPoolName)).getKeepAliveTime(TimeUnit.MINUTES), equalTo(0L));
        } finally {
            terminateThreadPoolIfNeeded(threadPool);
        }
    }

    public void testScalingExecutorType() throws InterruptedException {
        String threadPoolName = randomThreadPool(ThreadPool.ThreadPoolType.SCALING);
        ThreadPool threadPool = null;
        try {
            Settings nodeSettings = Settings.builder()
                .put("thread_pool." + threadPoolName + ".max", 10)
                .put("node.name", "testScalingExecutorType")
                .build();
            threadPool = new ThreadPool(nodeSettings, MeterRegistry.NOOP, new DefaultBuiltInExecutorBuilders());
            final int expectedMinimum = "generic".equals(threadPoolName) ? 4 : 1;
            assertThat(info(threadPool, threadPoolName).getMin(), equalTo(expectedMinimum));
            assertThat(info(threadPool, threadPoolName).getMax(), equalTo(10));
            final long expectedKeepAlive = "generic".equals(threadPoolName) || Names.SNAPSHOT_META.equals(threadPoolName) ? 30 : 300;
            assertThat(info(threadPool, threadPoolName).getKeepAlive().seconds(), equalTo(expectedKeepAlive));
            assertEquals(info(threadPool, threadPoolName).getThreadPoolType(), ThreadPool.ThreadPoolType.SCALING);
            assertThat(threadPool.executor(threadPoolName), instanceOf(EsThreadPoolExecutor.class));
        } finally {
            terminateThreadPoolIfNeeded(threadPool);
        }
    }

    public void testShutdownNowInterrupts() throws Exception {
        String threadPoolName = randomThreadPool(ThreadPool.ThreadPoolType.FIXED);
        ThreadPool threadPool = null;
        try {
            Settings nodeSettings = Settings.builder()
                .put("thread_pool." + threadPoolName + ".queue_size", 1000)
                .put("node.name", "testShutdownNowInterrupts")
                .build();
            threadPool = new ThreadPool(nodeSettings, MeterRegistry.NOOP, new DefaultBuiltInExecutorBuilders());
            assertEquals(info(threadPool, threadPoolName).getQueueSize().singles(), 1000L);

            final CountDownLatch shutDownLatch = new CountDownLatch(1);
            final CountDownLatch latch = new CountDownLatch(1);
            ThreadPoolExecutor oldExecutor = (ThreadPoolExecutor) threadPool.executor(threadPoolName);
            threadPool.executor(threadPoolName).execute(() -> {
                try {
                    shutDownLatch.countDown();
                    new CountDownLatch(1).await();
                } catch (InterruptedException ex) {
                    latch.countDown();
                    Thread.currentThread().interrupt();
                }
            });
            shutDownLatch.await();
            threadPool.shutdownNow();
            latch.await(3, TimeUnit.SECONDS); // if this throws then ThreadPool#shutdownNow did not interrupt
            assertThat(oldExecutor.isShutdown(), equalTo(true));
            assertThat(oldExecutor.isTerminating() || oldExecutor.isTerminated(), equalTo(true));
        } finally {
            terminateThreadPoolIfNeeded(threadPool);
        }
    }

    public void testCustomThreadPool() throws Exception {
        ThreadPool threadPool = null;
        try {
            final ScalingExecutorBuilder scaling = new ScalingExecutorBuilder(
                "my_pool1",
                1,
                EsExecutors.allocatedProcessors(Settings.EMPTY),
                TimeValue.timeValueMinutes(1),
                randomBoolean()
            );

            final FixedExecutorBuilder fixed = new FixedExecutorBuilder(
                Settings.EMPTY,
                "my_pool2",
                1,
                1,
                EsExecutors.TaskTrackingConfig.DO_NOT_TRACK
            );

            threadPool = new ThreadPool(
                Settings.builder().put("node.name", "testCustomThreadPool").build(),
                MeterRegistry.NOOP,
                new DefaultBuiltInExecutorBuilders(),
                scaling,
                fixed
            );

            ThreadPoolInfo groups = threadPool.info();
            boolean foundPool1 = false;
            boolean foundPool2 = false;
            outer: for (ThreadPool.Info info : groups) {
                if ("my_pool1".equals(info.getName())) {
                    foundPool1 = true;
                    assertEquals(info.getThreadPoolType(), ThreadPool.ThreadPoolType.SCALING);
                } else if ("my_pool2".equals(info.getName())) {
                    foundPool2 = true;
                    assertEquals(info.getThreadPoolType(), ThreadPool.ThreadPoolType.FIXED);
                    assertThat(info.getMin(), equalTo(1));
                    assertThat(info.getMax(), equalTo(1));
                    assertThat(info.getQueueSize().singles(), equalTo(1L));
                } else {
                    for (Field field : Names.class.getFields()) {
                        if (info.getName().equalsIgnoreCase(field.getName())) {
                            // This is ok it is a default thread pool
                            continue outer;
                        }
                    }
                    fail("Unexpected pool name: " + info.getName());
                }
            }
            assertThat(foundPool1, is(true));
            assertThat(foundPool2, is(true));
        } finally {
            terminateThreadPoolIfNeeded(threadPool);
        }
    }

    private String randomThreadPoolName() {
        Set<String> threadPoolNames = ThreadPool.THREAD_POOL_TYPES.keySet();
        return randomFrom(threadPoolNames.toArray(new String[threadPoolNames.size()]));
    }

}