/*
 * 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.iotdb.db.mpp.execution.fragment;

import org.apache.iotdb.commons.concurrent.IoTDBThreadPoolFactory;
import org.apache.iotdb.commons.concurrent.ThreadName;
import org.apache.iotdb.commons.concurrent.threadpool.ScheduledExecutorUtil;
import org.apache.iotdb.db.conf.IoTDBDescriptor;
import org.apache.iotdb.db.engine.storagegroup.IDataRegionForQuery;
import org.apache.iotdb.db.metadata.schemaregion.ISchemaRegion;
import org.apache.iotdb.db.mpp.common.FragmentInstanceId;
import org.apache.iotdb.db.mpp.execution.driver.IDriver;
import org.apache.iotdb.db.mpp.execution.exchange.sink.ISink;
import org.apache.iotdb.db.mpp.execution.schedule.DriverScheduler;
import org.apache.iotdb.db.mpp.execution.schedule.IDriverScheduler;
import org.apache.iotdb.db.mpp.metric.QueryExecutionMetricSet;
import org.apache.iotdb.db.mpp.plan.planner.LocalExecutionPlanner;
import org.apache.iotdb.db.mpp.plan.planner.PipelineDriverFactory;
import org.apache.iotdb.db.mpp.plan.planner.plan.FragmentInstance;
import org.apache.iotdb.db.utils.SetThreadName;

import io.airlift.stats.CounterStat;
import io.airlift.units.Duration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

import static java.util.Objects.requireNonNull;
import static org.apache.iotdb.db.mpp.execution.fragment.FragmentInstanceContext.createFragmentInstanceContext;
import static org.apache.iotdb.db.mpp.execution.fragment.FragmentInstanceExecution.createFragmentInstanceExecution;
import static org.apache.iotdb.db.mpp.metric.QueryExecutionMetricSet.LOCAL_EXECUTION_PLANNER;

public class FragmentInstanceManager {

  private static final Logger logger = LoggerFactory.getLogger(FragmentInstanceManager.class);

  private final Map<FragmentInstanceId, FragmentInstanceContext> instanceContext;
  private final Map<FragmentInstanceId, FragmentInstanceExecution> instanceExecution;
  private final LocalExecutionPlanner planner = LocalExecutionPlanner.getInstance();
  private final IDriverScheduler scheduler = DriverScheduler.getInstance();

  private final ScheduledExecutorService instanceManagementExecutor;
  public final ExecutorService instanceNotificationExecutor;

  private final Duration infoCacheTime;

  // record failed instances count
  public final CounterStat failedInstances = new CounterStat();

  private final ExecutorService intoOperationExecutor;

  private static final QueryExecutionMetricSet QUERY_EXECUTION_METRIC_SET =
      QueryExecutionMetricSet.getInstance();

  public static FragmentInstanceManager getInstance() {
    return FragmentInstanceManager.InstanceHolder.INSTANCE;
  }

  private FragmentInstanceManager() {
    this.instanceContext = new ConcurrentHashMap<>();
    this.instanceExecution = new ConcurrentHashMap<>();
    this.instanceManagementExecutor =
        IoTDBThreadPoolFactory.newScheduledThreadPool(
            1, ThreadName.FRAGMENT_INSTANCE_MANAGEMENT.getName());
    this.instanceNotificationExecutor =
        IoTDBThreadPoolFactory.newFixedThreadPool(
            4, ThreadName.FRAGMENT_INSTANCE_NOTIFICATION.getName());

    this.infoCacheTime = new Duration(5, TimeUnit.MINUTES);

    ScheduledExecutorUtil.safelyScheduleWithFixedDelay(
        instanceManagementExecutor, this::removeOldInstances, 2000, 2000, TimeUnit.MILLISECONDS);
    ScheduledExecutorUtil.safelyScheduleWithFixedDelay(
        instanceManagementExecutor,
        this::cancelTimeoutFlushingInstances,
        2000,
        2000,
        TimeUnit.MILLISECONDS);

    this.intoOperationExecutor =
        IoTDBThreadPoolFactory.newFixedThreadPool(
            IoTDBDescriptor.getInstance().getConfig().getIntoOperationExecutionThreadCount(),
            "into-operation-executor");
  }

  public int getInstanceContextSize() {
    return instanceContext.size();
  }

  public int getInstanceExecutionSize() {
    return instanceExecution.size();
  }

  public FragmentInstanceInfo execDataQueryFragmentInstance(
      FragmentInstance instance, IDataRegionForQuery dataRegion) {
    long startTime = System.nanoTime();
    FragmentInstanceId instanceId = instance.getId();
    try (SetThreadName fragmentInstanceName = new SetThreadName(instanceId.getFullId())) {
      FragmentInstanceExecution execution =
          instanceExecution.computeIfAbsent(
              instanceId,
              id -> {
                FragmentInstanceStateMachine stateMachine =
                    new FragmentInstanceStateMachine(instanceId, instanceNotificationExecutor);

                FragmentInstanceContext context =
                    instanceContext.computeIfAbsent(
                        instanceId,
                        fragmentInstanceId ->
                            createFragmentInstanceContext(
                                fragmentInstanceId,
                                stateMachine,
                                instance.getSessionInfo(),
                                dataRegion,
                                instance.getTimeFilter()));

                try {
                  List<PipelineDriverFactory> driverFactories =
                      planner.plan(
                          instance.getFragment().getPlanNodeTree(),
                          instance.getFragment().getTypeProvider(),
                          context);

                  List<IDriver> drivers = new ArrayList<>();
                  driverFactories.forEach(factory -> drivers.add(factory.createDriver()));
                  context.initializeNumOfDrivers(drivers.size());
                  // get the sink of last driver
                  ISink sink = drivers.get(drivers.size() - 1).getSink();

                  return createFragmentInstanceExecution(
                      scheduler,
                      instanceId,
                      context,
                      drivers,
                      sink,
                      stateMachine,
                      failedInstances,
                      instance.getTimeOut());
                } catch (Throwable t) {
                  logger.warn("error when create FragmentInstanceExecution.", t);
                  stateMachine.failed(t);
                  return null;
                }
              });

      if (execution != null) {
        execution
            .getStateMachine()
            .addStateChangeListener(
                newState -> {
                  if (newState.isDone()) {
                    instanceExecution.remove(instanceId);
                  }
                });
        return execution.getInstanceInfo();
      } else {
        return createFailedInstanceInfo(instanceId);
      }
    } finally {
      QUERY_EXECUTION_METRIC_SET.recordExecutionCost(
          LOCAL_EXECUTION_PLANNER, System.nanoTime() - startTime);
    }
  }

  public FragmentInstanceInfo execSchemaQueryFragmentInstance(
      FragmentInstance instance, ISchemaRegion schemaRegion) {
    FragmentInstanceId instanceId = instance.getId();
    FragmentInstanceExecution execution =
        instanceExecution.computeIfAbsent(
            instanceId,
            id -> {
              FragmentInstanceStateMachine stateMachine =
                  new FragmentInstanceStateMachine(instanceId, instanceNotificationExecutor);

              FragmentInstanceContext context =
                  instanceContext.computeIfAbsent(
                      instanceId,
                      fragmentInstanceId ->
                          createFragmentInstanceContext(
                              fragmentInstanceId, stateMachine, instance.getSessionInfo()));

              try {
                List<PipelineDriverFactory> driverFactories =
                    planner.plan(instance.getFragment().getPlanNodeTree(), context, schemaRegion);

                List<IDriver> drivers = new ArrayList<>();
                driverFactories.forEach(factory -> drivers.add(factory.createDriver()));
                context.initializeNumOfDrivers(drivers.size());
                // get the sink of last driver
                ISink sink = drivers.get(drivers.size() - 1).getSink();

                return createFragmentInstanceExecution(
                    scheduler,
                    instanceId,
                    context,
                    drivers,
                    sink,
                    stateMachine,
                    failedInstances,
                    instance.getTimeOut());
              } catch (Throwable t) {
                logger.warn("Execute error caused by ", t);
                stateMachine.failed(t);
                return null;
              }
            });
    if (execution != null) {
      execution
          .getStateMachine()
          .addStateChangeListener(
              newState -> {
                if (newState.isDone()) {
                  instanceExecution.remove(instanceId);
                }
              });
      return execution.getInstanceInfo();
    } else {
      return createFailedInstanceInfo(instanceId);
    }
  }

  /** Aborts a FragmentInstance. keep FragmentInstanceContext for later state tracking */
  public FragmentInstanceInfo abortFragmentInstance(FragmentInstanceId fragmentInstanceId) {
    instanceExecution.remove(fragmentInstanceId);
    FragmentInstanceContext context = instanceContext.get(fragmentInstanceId);
    if (context != null) {
      context.abort();
      return context.getInstanceInfo();
    }
    return null;
  }

  /** Cancels a FragmentInstance. */
  public FragmentInstanceInfo cancelTask(FragmentInstanceId instanceId, boolean hasThrowable) {
    logger.debug("[CancelFI]");
    requireNonNull(instanceId, "taskId is null");

    FragmentInstanceContext context = instanceContext.remove(instanceId);
    if (context != null) {
      instanceExecution.remove(instanceId);
      if (hasThrowable) {
        context.cancel();
      } else {
        context.finished();
      }
      return context.getInstanceInfo();
    }
    return null;
  }

  /**
   * Gets the info for the specified fragment instance.
   *
   * <p>NOTE: this design assumes that only fragment instances that will eventually exist are
   * queried.
   */
  public FragmentInstanceInfo getInstanceInfo(FragmentInstanceId instanceId) {
    requireNonNull(instanceId, "instanceId is null");
    FragmentInstanceContext context = instanceContext.get(instanceId);
    if (context == null) {
      return null;
    }
    return context.getInstanceInfo();
  }

  public CounterStat getFailedInstances() {
    return failedInstances;
  }

  private FragmentInstanceInfo createFailedInstanceInfo(FragmentInstanceId instanceId) {
    FragmentInstanceContext context = instanceContext.get(instanceId);
    return new FragmentInstanceInfo(
        FragmentInstanceState.FAILED,
        context.getEndTime(),
        context.getFailedCause(),
        context.getFailureInfoList());
  }

  private void removeOldInstances() {
    long oldestAllowedInstance = System.currentTimeMillis() - infoCacheTime.toMillis();
    instanceContext
        .entrySet()
        .removeIf(
            entry -> {
              long endTime = entry.getValue().getEndTime();
              return endTime != -1 && endTime <= oldestAllowedInstance;
            });
  }

  private void cancelTimeoutFlushingInstances() {
    long now = System.currentTimeMillis();
    instanceExecution.forEach(
        (key, execution) -> {
          if (execution.getStateMachine().getState() == FragmentInstanceState.FLUSHING
              && (now - execution.getStartTime()) > execution.getTimeoutInMs()) {
            execution
                .getStateMachine()
                .failed(
                    new TimeoutException(
                        "Query has executed more than " + execution.getTimeoutInMs() + "ms"));
          }
        });
  }

  public ExecutorService getIntoOperationExecutor() {
    return intoOperationExecutor;
  }

  private static class InstanceHolder {

    private InstanceHolder() {}

    private static final FragmentInstanceManager INSTANCE = new FragmentInstanceManager();
  }
}
