/*
 * 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.cassandra.sidecar.testing;

import java.io.IOException;
import java.net.UnknownHostException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.function.Consumer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import com.google.common.collect.ImmutableMap;
import com.google.common.util.concurrent.Uninterruptibles;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.TestInfo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.datastax.driver.core.Session;
import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.util.Modules;
import io.vertx.core.Vertx;
import io.vertx.core.eventbus.Message;
import io.vertx.core.eventbus.MessageConsumer;
import io.vertx.core.json.JsonObject;
import io.vertx.ext.web.client.WebClient;
import io.vertx.ext.web.client.predicate.ResponsePredicate;
import io.vertx.junit5.VertxTestContext;
import org.apache.cassandra.sidecar.cluster.CassandraAdapterDelegate;
import org.apache.cassandra.sidecar.cluster.InstancesConfig;
import org.apache.cassandra.sidecar.cluster.instance.InstanceMetadata;
import org.apache.cassandra.sidecar.common.dns.DnsResolver;
import org.apache.cassandra.sidecar.server.MainModule;
import org.apache.cassandra.sidecar.server.Server;
import org.apache.cassandra.testing.AbstractCassandraTestContext;

import static org.apache.cassandra.sidecar.server.SidecarServerEvents.ON_CASSANDRA_CQL_READY;
import static org.apache.cassandra.testing.TestUtils.TEST_KEYSPACE;
import static org.apache.cassandra.testing.TestUtils.TEST_TABLE_PREFIX;
import static org.apache.cassandra.testing.TestUtils.uniqueTestTableFullName;
import static org.assertj.core.api.Assertions.assertThat;

/**
 * Base class for integration test.
 * Start an in-jvm dtest cluster at the beginning of each test, and
 * teardown the cluster after each test.
 */
public abstract class IntegrationTestBase
{
    private static final int MAX_KEYSPACE_TABLE_WAIT_ATTEMPTS = 120;
    private static final long MAX_KEYSPACE_TABLE_TIME = 1000L;
    protected static final int DEFAULT_RF = 3;


    protected Logger logger = LoggerFactory.getLogger(this.getClass());
    protected Vertx vertx;
    protected Server server;
    protected WebClient client;
    protected CassandraSidecarTestContext sidecarTestContext;
    protected Injector injector;

    @BeforeEach
    void setup(AbstractCassandraTestContext cassandraTestContext, TestInfo testInfo) throws InterruptedException
    {
        IntegrationTestModule integrationTestModule = new IntegrationTestModule();
        System.setProperty("cassandra.testtag", testInfo.getTestClass().get().getSimpleName());
        System.setProperty("suitename", testInfo.getTestMethod().get().getName() + "-" + cassandraTestContext.version);
        int clusterSize = cassandraTestContext.clusterSize();
        injector = Guice.createInjector(Modules.override(new MainModule()).with(integrationTestModule));
        vertx = injector.getInstance(Vertx.class);
        sidecarTestContext = CassandraSidecarTestContext.from(vertx, cassandraTestContext, new LocalhostResolver(),
                                                              getNumInstancesToManage(clusterSize));

        integrationTestModule.setCassandraTestContext(sidecarTestContext);

        server = injector.getInstance(Server.class);
        VertxTestContext context = new VertxTestContext();

        if (sidecarTestContext.isClusterBuilt())
        {
            MessageConsumer<JsonObject> cqlReadyConsumer = vertx.eventBus()
                                                                .localConsumer(ON_CASSANDRA_CQL_READY.address());
            cqlReadyConsumer.handler(message -> {
                cqlReadyConsumer.unregister();
                context.completeNow();
            });
        }

        client = WebClient.create(vertx);
        server.start()
              .onSuccess(s -> {
                  sidecarTestContext.registerInstanceConfigListener(this::healthCheck);
                  if (!sidecarTestContext.isClusterBuilt())
                  {
                      // Give everything a moment to get started and connected
                      vertx.setTimer(TimeUnit.SECONDS.toMillis(1), id1 -> context.completeNow());
                  }
              })
              .onFailure(context::failNow);

        context.awaitCompletion(5, TimeUnit.SECONDS);
    }

    /**
     * Some tests may want to "manage" fewer instances than the complete cluster.
     * Therefore, override this if your test wants to manage fewer than the complete cluster size.
     * The Sidecar will be configured to manage the first N instances in the cluster by instance number.
     * Defaults to the entire cluster.
     *
     * @param clusterSize the size of the cluster as defined by the integration test
     * @return the number of instances to manage
     */
    protected int getNumInstancesToManage(int clusterSize)
    {
        return clusterSize;
    }

    @AfterEach
    void tearDown() throws InterruptedException
    {
        CountDownLatch closeLatch = new CountDownLatch(1);
        client.close();
        server.close().onSuccess(res -> closeLatch.countDown());
        if (closeLatch.await(60, TimeUnit.SECONDS))
        {
            logger.info("Close event received before timeout.");
        }
        else
        {
            logger.error("Close event timed out.");
        }
        sidecarTestContext.close();
    }

    protected void testWithClient(VertxTestContext context, Consumer<WebClient> tester) throws Exception
    {
        testWithClient(context, true, tester);
    }

    protected void testWithClient(VertxTestContext context,
                                  boolean waitForCluster,
                                  Consumer<WebClient> tester)
    throws Exception
    {
        CassandraAdapterDelegate delegate = sidecarTestContext.instancesConfig()
                                                              .instanceFromId(1)
                                                              .delegate();

        assertThat(delegate).isNotNull();
        if (delegate.isNativeUp() || !waitForCluster)
        {
            tester.accept(client);
        }
        else
        {
            vertx.eventBus().localConsumer(ON_CASSANDRA_CQL_READY.address(), (Message<JsonObject> message) -> {
                if (message.body().getInteger("cassandraInstanceId") == 1)
                {
                    tester.accept(client);
                }
            });
        }

        // wait until the test completes
        assertThat(context.awaitCompletion(2, TimeUnit.MINUTES)).isTrue();
    }

    protected void createTestKeyspace()
    {
        createTestKeyspace(TEST_KEYSPACE, ImmutableMap.of("datacenter1", 1));
    }

    protected void createTestKeyspace(String keyspace)
    {
        createTestKeyspace(keyspace, ImmutableMap.of("datacenter1", 1));
    }

    protected void createTestKeyspace(String keyspace, Map<String, Integer> rf)
    {
        int attempts = 1;
        ArrayList<Throwable> thrown = new ArrayList<>(5);
        while (attempts <= 5)
        {
            try
            {
                Session session = maybeGetSession();

                session.execute("CREATE KEYSPACE IF NOT EXISTS " + keyspace +
                                " WITH REPLICATION = { 'class' : 'NetworkTopologyStrategy', " +
                                generateRfString(rf) + " };");
                session.getCluster().getMetadata().checkSchemaAgreement();
                return;
            }
            catch (Throwable t)
            {
                thrown.add(t);
                logger.debug("Failed to create keyspace {} on attempt {}", keyspace, attempts);
                attempts++;
                Uninterruptibles.sleepUninterruptibly(1, TimeUnit.SECONDS);
            }
        }
        RuntimeException rte = new RuntimeException("Could not create test keyspace " + keyspace + " after 5 attempts.");
        thrown.forEach(rte::addSuppressed);
        throw rte;
    }

    protected String generateRfString(Map<String, Integer> dcToRf)
    {
        return dcToRf.entrySet().stream().map(e -> String.format("'%s':%d", e.getKey(), e.getValue()))
                     .collect(Collectors.joining(","));
    }

    protected QualifiedName createTestTable(String createTableStatement)
    {
        return createTestTable(TEST_TABLE_PREFIX, createTableStatement);
    }

    protected QualifiedName createTestTable(String tablePrefix, String createTableStatement)
    {
        int attempts = 1;
        ArrayList<Throwable> thrown = new ArrayList<>(5);
        QualifiedName tableName = uniqueTestTableFullName(tablePrefix);
        while (attempts <= 5)
        {
            try
            {
                Session session = maybeGetSession();
                session.execute(String.format(createTableStatement, tableName));
                return tableName;
            }
            catch (Throwable t)
            {
                thrown.add(t);
                logger.debug("Failed to create table {} on attempt {}", tableName, attempts);
                attempts++;
                Uninterruptibles.sleepUninterruptibly(1, TimeUnit.SECONDS);
            }
        }
        RuntimeException rte = new RuntimeException("Could not create test table " + tableName +
                                                    " after 5 attempts.");
        thrown.forEach(rte::addSuppressed);
        throw rte;
    }

    protected Session maybeGetSession()
    {
        Session session = sidecarTestContext.session();
        assertThat(session).isNotNull();
        return session;
    }

    public List<Path> findChildFile(CassandraSidecarTestContext context, String hostname, String target)
    {
        InstanceMetadata instanceConfig = context.instancesConfig().instanceFromHost(hostname);
        List<String> parentDirectories = instanceConfig.dataDirs();

        return parentDirectories.stream().flatMap(s -> findChildFile(Paths.get(s), target).stream())
                                .collect(Collectors.toList());
    }

    private List<Path> findChildFile(Path path, String target)
    {
        try (Stream<Path> walkStream = Files.walk(path))
        {
            return walkStream.filter(p -> p.toString().endsWith(target)
                                          || p.toString().contains("/" + target + "/"))
                             .collect(Collectors.toList());
        }
        catch (IOException e)
        {
            return Collections.emptyList();
        }
    }

    private void healthCheck(InstancesConfig instancesConfig)
    {
        instancesConfig.instances()
                       .forEach(instanceMetadata -> instanceMetadata.delegate().healthCheck());
    }

    /**
     * Waits for the specified keyspace to be available in Sidecar.
     * Empirically, this loop usually executes either zero or one time before completing.
     * However, we set a fairly high number of retries to account for variability in build machines.
     *
     * @param keyspace the keyspace for which to wait
     */
    protected void waitUntilSidecarPicksUpSchemaChange(String keyspace)
    {
        int retries = MAX_KEYSPACE_TABLE_WAIT_ATTEMPTS;
        WebClient client = WebClient.create(vertx);
        while (retries-- > 0)
        {
            try
            {
                client.get(server.actualPort(), "localhost", "/api/v1/keyspaces/" + keyspace + "/schema")
                      .expect(ResponsePredicate.SC_OK)
                      .send()
                      .toCompletionStage()
                      .toCompletableFuture()
                      .get(MAX_KEYSPACE_TABLE_TIME, TimeUnit.MILLISECONDS);
                logger.info("Schema is ready in Sidecar");
                client.close();
                return;
            }
            catch (Exception exception)
            {
                logger.info("Waiting for schema to propagate to Sidecar");
                Uninterruptibles.sleepUninterruptibly(MAX_KEYSPACE_TABLE_TIME, TimeUnit.MILLISECONDS);
            }
        }
        client.close();
        throw new RuntimeException(String.format("Keyspace %s did not become visible in Sidecar", keyspace));
    }

    /**
     * A {@link DnsResolver} instance used for tests that provides fast DNS resolution, to avoid blocking
     * DNS resolution at the JDK/OS-level.
     *
     * <p><b>NOTE:</b> The resolver assumes that the addresses are of the form 127.0.0.x, which is what is currently
     * configured for integration tests.
     */
    static class LocalhostResolver implements DnsResolver
    {
        private static final Logger LOGGER = LoggerFactory.getLogger(LocalhostResolver.class);
        private static final Pattern HOSTNAME_PATTERN = Pattern.compile("^localhost(\\d+)?$");
        private final DnsResolver delegate;

        LocalhostResolver()
        {
            this(DnsResolver.DEFAULT);
        }

        LocalhostResolver(DnsResolver delegate)
        {

            this.delegate = delegate;
        }

        /**
         * Returns the resolved IP address from the hostname. If the {@code hostname} pattern is not matched,
         * delegate the resolution to the delegate resolver.
         *
         * <pre>
         * resolver.resolve("localhost") = "127.0.0.1"
         * resolver.resolve("localhost2") = "127.0.0.2"
         * resolver.resolve("localhost20") = "127.0.0.20"
         * resolver.resolve("127.0.0.5") = "127.0.0.5"
         * </pre>
         *
         * @param hostname the hostname to resolve
         * @return the resolved IP address
         */
        @Override
        public String resolve(String hostname) throws UnknownHostException
        {
            Matcher matcher = HOSTNAME_PATTERN.matcher(hostname);
            if (!matcher.matches())
            {
                LOGGER.warn("Invalid hostname found {}.", hostname);
                return delegate.resolve(hostname);
            }
            String group = matcher.group(1);
            return "127.0.0." + (group != null ? group : "1");
        }

        /**
         * Returns the resolved hostname from the given {@code address}. When an invalid IP address is provided,
         * delegates {@code address} resolution to the delegate.
         *
         * <pre>
         * resolver.reverseResolve("127.0.0.1") = "localhost"
         * resolver.reverseResolve("127.0.0.2") = "localhost2"
         * resolver.reverseResolve("127.0.0.20") = "localhost20"
         * resolver.reverseResolve("localhost5") = "localhost5"
         * </pre>
         *
         * @param address the IP address to perform the reverse resolution
         * @return the resolved hostname for the given {@code address}
         */
        @Override
        public String reverseResolve(String address) throws UnknownHostException
        {
            // IP addresses have the form 127.0.0.x
            int lastDotIndex = address.lastIndexOf('.');
            if (lastDotIndex < 0 || lastDotIndex + 1 == address.length())
            {
                LOGGER.warn("Invalid ip address found {}.", address);
                return delegate.reverseResolve(address);
            }
            String netNumber = address.substring(lastDotIndex + 1);
            return "1".equals(netNumber) ? "localhost" : "localhost" + netNumber;
        }
    }
}