/*
 * ToroDB
 * Copyright © 2014 8Kdata Technology (www.8kdata.com)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

package com.torodb.stampede;

import com.eightkdata.mongowp.client.wrapper.MongoClientConfiguration;
import com.google.common.util.concurrent.AbstractIdleService;
import com.google.common.util.concurrent.Service;
import com.google.inject.Injector;
import com.torodb.core.Shutdowner;
import com.torodb.core.backend.BackendBundle;
import com.torodb.core.backend.BackendBundleFactory;
import com.torodb.core.backend.BackendConnection;
import com.torodb.core.backend.BackendService;
import com.torodb.core.backend.ExclusiveWriteBackendTransaction;
import com.torodb.core.exceptions.user.UserException;
import com.torodb.core.retrier.Retrier;
import com.torodb.core.supervision.Supervisor;
import com.torodb.core.supervision.SupervisorDecision;
import com.torodb.mongodb.repl.ConsistencyHandler;
import com.torodb.mongodb.repl.MongodbReplBundle;
import com.torodb.mongodb.repl.ReplicationFilters;
import com.torodb.mongodb.repl.guice.MongodbReplConfig;
import com.torodb.packaging.config.model.protocol.mongo.AbstractReplication;
import com.torodb.packaging.util.MongoClientConfigurationFactory;
import com.torodb.packaging.util.ReplicationFiltersFactory;
import com.torodb.stampede.config.model.Config;
import com.torodb.torod.TorodBundle;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.util.concurrent.Executor;
import java.util.concurrent.ThreadFactory;

/**
 *
 */
public class StampedeService extends AbstractIdleService implements Supervisor {

  private static final Logger LOGGER =
      LogManager.getLogger(StampedeService.class);
  private final ThreadFactory threadFactory;
  private final Injector bootstrapInjector;
  private Shutdowner shutdowner;

  public StampedeService(ThreadFactory threadFactory, Injector bootstrapInjector) {
    this.threadFactory = threadFactory;
    this.bootstrapInjector = bootstrapInjector;
  }

  @Override
  protected Executor executor() {
    return (Runnable command) -> {
      Thread thread = threadFactory.newThread(command);
      thread.start();
    };
  }

  @Override
  public SupervisorDecision onError(Object supervised, Throwable error) {
    LOGGER.error("Error reported by " + supervised + ". Stopping ToroDB Stampede", error);
    this.stopAsync();
    return SupervisorDecision.IGNORE;
  }

  @Override
  protected void startUp() throws Exception {
    LOGGER.info("Starting up ToroDB Stampede");

    shutdowner = bootstrapInjector.getInstance(Shutdowner.class);
    shutdowner.awaitRunning();

    BackendBundle backendBundle = createBackendBundle();
    startBundle(backendBundle);

    BackendService backendService = backendBundle.getBackendService();

    ConsistencyHandler consistencyHandler = createConsistencyHandler(
        backendService);
    if (!consistencyHandler.isConsistent()) {
      LOGGER.info("Database is not consistent. Cleaning it up");
      dropDatabase(backendService);
    }

    Injector finalInjector = createFinalInjector(
        backendBundle, consistencyHandler);

    AbstractReplication replication = getReplication();
    reportReplication(replication);
    TorodBundle torodBundle = createTorodBundle(finalInjector);
    startBundle(torodBundle);

    MongodbReplConfig replConfig = getReplConfig(replication);

    startBundle(createMongodbReplBundle(finalInjector, torodBundle, replConfig));

    LOGGER.info("ToroDB Stampede is now running");
  }

  @Override
  protected void shutDown() throws Exception {
    LOGGER.info("Shutting down ToroDB Stampede");
    if (shutdowner != null) {
      shutdowner.stopAsync();
      shutdowner.awaitTerminated();
    }
    LOGGER.info("ToroDB Stampede has been shutted down");
  }

  private BackendBundle createBackendBundle() {
    return bootstrapInjector.getInstance(BackendBundleFactory.class)
        .createBundle(this);
  }

  private ConsistencyHandler createConsistencyHandler(BackendService backendService) {
    Retrier retrier = bootstrapInjector.getInstance(Retrier.class);
    return new DefaultConsistencyHandler(backendService, retrier);
  }

  private void dropDatabase(BackendService backendService) throws UserException {
    try (BackendConnection conn = backendService.openConnection();
        ExclusiveWriteBackendTransaction trans = conn.openExclusiveWriteTransaction()) {
      trans.dropUserData();
      trans.commit();
    }
  }

  private Injector createFinalInjector(BackendBundle backendBundle,
      ConsistencyHandler consistencyHandler) {
    StampedeRuntimeModule runtimeModule = new StampedeRuntimeModule(
        backendBundle, this, consistencyHandler);
    return bootstrapInjector.createChildInjector(runtimeModule);
  }

  private MongodbReplBundle createMongodbReplBundle(Injector finalInjector,
      TorodBundle torodBundle, MongodbReplConfig replConfig) {
    return new MongodbReplBundle(torodBundle, this, replConfig, finalInjector);
  }

  private TorodBundle createTorodBundle(Injector finalInjector) {
    return finalInjector.getInstance(TorodBundle.class);
  }

  private void startBundle(Service service) {
    service.startAsync();
    service.awaitRunning();

    shutdowner.addStopShutdownListener(service);
  }

  private AbstractReplication getReplication() {
    Config config = bootstrapInjector.getInstance(Config.class);
    return config.getReplication();
  }

  private void reportReplication(AbstractReplication replication) {
    LOGGER.info("Replicating from seeds: {}", replication.getSyncSource());
  }

  private MongodbReplConfig getReplConfig(AbstractReplication replication) {
    return new DefaultMongodbReplConfig(replication);
  }

  private static class DefaultMongodbReplConfig implements MongodbReplConfig {

    private final MongoClientConfiguration mongoClientConf;
    private final ReplicationFilters replFilters;
    private final String replSetName;

    public DefaultMongodbReplConfig(AbstractReplication replication) {
      this.mongoClientConf = MongoClientConfigurationFactory
          .getMongoClientConfiguration(replication);
      this.replFilters = ReplicationFiltersFactory.getReplicationFilters(replication);
      replSetName = replication.getReplSetName();
    }

    @Override
    public MongoClientConfiguration getMongoClientConfiguration() {
      return mongoClientConf;
    }

    @Override
    public ReplicationFilters getReplicationFilters() {
      return replFilters;
    }

    @Override
    public String getReplSetName() {
      return replSetName;
    }
  }

}