/**
 * 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.lens.server.api.query;

import static org.apache.lens.server.api.LensConfConstants.*;

import java.util.*;
import java.util.concurrent.Future;

import org.apache.lens.api.LensConf;
import org.apache.lens.api.query.FailedAttempt;
import org.apache.lens.api.query.LensQuery;
import org.apache.lens.api.query.QueryHandle;
import org.apache.lens.api.query.QueryStatus;
import org.apache.lens.api.query.QueryStatus.Status;
import org.apache.lens.server.api.LensConfConstants;
import org.apache.lens.server.api.driver.*;
import org.apache.lens.server.api.error.LensException;
import org.apache.lens.server.api.query.constraint.QueryLaunchingConstraint;
import org.apache.lens.server.api.retry.BackOffRetryHandler;
import org.apache.lens.server.api.retry.FailureContext;
import org.apache.lens.server.api.util.LensUtil;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;

import lombok.Getter;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;

/**
 * The Class QueryContext.
 */
@Slf4j
public class QueryContext extends AbstractQueryContext implements FailureContext {

  /**
   * The Constant serialVersionUID.
   */
  private static final long serialVersionUID = 1L;

  /**
   * The query handle.
   */
  @Getter
  @Setter
  private QueryHandle queryHandle;

  /**
   * The is persistent.
   */
  @Getter
  private final boolean isPersistent;

  /**
   * The is driver persistent.
   */
  @Getter
  private boolean isDriverPersistent;

  /**
   * The status.
   */
  @Getter
  private QueryStatus status;

  /**
   * The result set path.
   */
  @Getter
  @Setter
  private String resultSetPath;

  /**
   * The hdfsout path.
   */
  @Getter
  @Setter
  private String driverResultPath;

  /**
   * The submission time.
   */
  @Getter
  private final long submissionTime;

  /**
   * The launch time.
   */
  @Getter
  @Setter
  private long launchTime;

  /**
   * The end time.
   */
  @Getter
  @Setter
  private long endTime;

  /**
   * The closed time.
   */
  @Getter
  @Setter
  private long closedTime;

  /**
   * The driver op handle.
   */
  @Getter
  @Setter
  private String driverOpHandle;

  /**
   * The driver status.
   */
  @Getter
  final DriverQueryStatus driverStatus;

  /**
   * The query output formatter.
   */

  @Getter
  @Setter
  private QueryOutputFormatter queryOutputFormatter;

  /**
   * The finished query persisted.
   */
  @Getter
  @Setter
  private boolean finishedQueryPersisted = false;

  @Getter
  @Setter
  private boolean isQueryClosedOnDriver = false;

  /**
   * The query name.
   */
  @Getter
  @Setter
  private String queryName;

  /**
   * This is the timeout that the client may have provided while initiating query execution
   * This value is used for pre fetching in-memory result if applicable
   *
   * Note: in case the timeout is not provided, this value will not be set.
   */
  @Setter
  @Getter
  private transient long executeTimeoutMillis;

  /**
   * Query result registered by driver
   */
  @Getter
  private transient LensResultSet driverResult;

  /**
   * True if driver has registered the result
   */
  @Getter
  private transient boolean isDriverResultRegistered;

  @Getter
  @Setter
  private byte[] queryConfHash;

  transient StatusUpdateFailureContext statusUpdateFailures = new StatusUpdateFailureContext();

  @Getter
  @Setter
  private transient boolean isLaunching = false;

  @Getter
  @Setter
  private transient Future queryLauncher;
  transient List<QueryDriverStatusUpdateListener> driverStatusUpdateListeners = Lists.newCopyOnWriteArrayList();
  @Getter
  @Setter
  List<FailedAttempt> failedAttempts = Lists.newArrayList();

  @Getter
  @Setter
  private BackOffRetryHandler<QueryContext> driverRetryPolicy;
  @Getter
  @Setter
  private BackOffRetryHandler<QueryContext> serverRetryPolicy;

  /**
   * Creates context from query
   *
   * @param query the query
   * @param user  the user
   * @param qconf The query lensconf
   * @param conf  the conf
   */
  public QueryContext(String query, String user, LensConf qconf, Configuration conf, Collection<LensDriver> drivers) {
    this(query, user, qconf, conf, drivers, null, true);
  }

  /**
   * Creates context from PreparedQueryContext
   *
   * @param prepared the prepared
   * @param user     the user
   * @param qconf    the qconf
   * @param conf     the conf
   */
  public QueryContext(PreparedQueryContext prepared, String user, LensConf qconf, Configuration conf) {
    this(prepared.getUserQuery(), user, qconf, mergeConf(prepared.getConf(), conf), prepared.getDriverContext()
      .getDriverQueryContextMap().keySet(), prepared.getDriverContext().getSelectedDriver(), true);
    setDriverContext(prepared.getDriverContext());
    setSelectedDriverQuery(prepared.getSelectedDriverQuery());
    setSelectedDriverQueryCost(prepared.getSelectedDriverQueryCost());
  }

  /**
   * Create context by passing drivers and selected driver
   *
   * @param userQuery The user query
   * @param user Submitted user
   * @param qconf The query LensConf
   * @param conf The configuration object
   * @param drivers All the drivers
   * @param selectedDriver SelectedDriver
   */
  QueryContext(String userQuery, String user, LensConf qconf, Configuration conf, Collection<LensDriver> drivers,
    LensDriver selectedDriver, boolean mergeDriverConf) {
    this(userQuery, user, qconf, conf, drivers, selectedDriver, System.currentTimeMillis(), mergeDriverConf);
  }

  /**
   * Instantiates a new query context.
   *
   * @param userQuery      the user query
   * @param user           the user
   * @param qconf          the qconf
   * @param conf           the conf
   * @param drivers        All the drivers
   * @param selectedDriver the selected driver
   * @param submissionTime the submission time
   */
  QueryContext(String userQuery, String user, LensConf qconf, Configuration conf, Collection<LensDriver> drivers,
    LensDriver selectedDriver, long submissionTime, boolean mergeDriverConf) {
    super(userQuery, user, qconf, conf, drivers, mergeDriverConf);
    this.submissionTime = submissionTime;
    this.queryHandle = new QueryHandle(UUID.randomUUID());
    this.status = new QueryStatus(0.0f, null, Status.NEW, "Query just got created", false, null, null, null);
    this.lensConf = qconf;
    this.conf = conf;
    this.isPersistent = conf.getBoolean(LensConfConstants.QUERY_PERSISTENT_RESULT_SET,
      LensConfConstants.DEFAULT_PERSISTENT_RESULT_SET);
    this.isDriverPersistent = conf.getBoolean(LensConfConstants.QUERY_PERSISTENT_RESULT_INDRIVER,
      LensConfConstants.DEFAULT_DRIVER_PERSISTENT_RESULT_SET);
    this.userQuery = userQuery;
    if (selectedDriver != null) {
      this.setSelectedDriver(selectedDriver);
    }
    this.lensConf = qconf;
    this.driverStatus = new DriverQueryStatus();
  }

  /**
   * Utility create method to create context with single driver.
   *
   * @param query The user query
   * @param user The submitted query
   * @param qconf The query lens conf
   * @param conf Query configuration object - merged with session
   * @param driver The driver
   * @param lensSessionPublicId The session id
   *
   * @return QueryContext object
   */
  public static QueryContext createContextWithSingleDriver(String query, String user, LensConf qconf,
    Configuration conf, LensDriver driver, String lensSessionPublicId, boolean mergeDriverConf) {
    QueryContext ctx = new QueryContext(query, user, qconf, conf, Lists.newArrayList(driver), driver, mergeDriverConf);
    ctx.setLensSessionIdentifier(lensSessionPublicId);
    return ctx;
  }

  public void initTransientState() {
    super.initTransientState();
    statusUpdateFailures = new StatusUpdateFailureContext();
    driverStatusUpdateListeners = Lists.newArrayList();
  }

  /**
   * Merge conf.
   *
   * @param prepared the prepared
   * @param current  the current
   * @return the configuration
   */
  private static Configuration mergeConf(Configuration prepared, Configuration current) {
    Configuration conf = new Configuration(false);
    for (Map.Entry<String, String> entry : prepared) {
      conf.set(entry.getKey(), entry.getValue());
    }
    for (Map.Entry<String, String> entry : current) {
      conf.set(entry.getKey(), entry.getValue());
    }
    return conf;
  }

  public String getResultSetParentDir() {
    if (getSelectedDriver() != null && getSelectedDriverConf().get(LensConfConstants.RESULT_SET_PARENT_DIR) != null) {
      log.info("Fetching Parent Dir from driver conf:- "
              + getSelectedDriverConf().get(LensConfConstants.RESULT_SET_PARENT_DIR));
      return getSelectedDriverConf().get(LensConfConstants.RESULT_SET_PARENT_DIR);
    }
    return conf.get(LensConfConstants.RESULT_SET_PARENT_DIR, LensConfConstants.RESULT_SET_PARENT_DIR_DEFAULT);
  }

  public Path getHDFSResultDir() {
    return new Path(new Path(getResultSetParentDir(), conf.get(LensConfConstants.QUERY_HDFS_OUTPUT_PATH,
      LensConfConstants.DEFAULT_HDFS_OUTPUT_PATH)), queryHandle.toString());
  }

  /**
   * To lens query.
   *
   * @return the lens query
   */
  public LensQuery toLensQuery() {
    return new LensQuery(queryHandle, userQuery, super.getSubmittedUser(), getPriority(), isPersistent,
      getSelectedDriver() != null ? getSelectedDriver().getFullyQualifiedName() : null,
      getSelectedDriverQuery(),
      status,
      resultSetPath, driverOpHandle, lensConf, submissionTime, launchTime, driverStatus.getDriverStartTime(),
      driverStatus.getDriverFinishTime(), endTime, closedTime, queryName, getFailedAttempts());
  }

  public boolean isResultAvailableInDriver() {
    // result is available in driver if driverStatus.isResultSetAvailable() - will be true for fetching inmemory
    // result set.
    // if result is persisted in driver driverStatus.isResultSetAvailable() will be false but isDriverPersistent will
    // be true. So, for select queries, if result is persisted in driver, we return true so that the result can be
    //  fetched thru persistent resultset
    return driverStatus.isSuccessful() && (isDriverPersistent() || driverStatus.isResultSetAvailable());
  }

  /**
   * Set whether result is persisted on driver to false. Set by drivers when drivers are not persisting
   *
   */
  public void unSetDriverPersistent() {
    isDriverPersistent = false;
  }

  /*
   * Introduced for Recovering finished query.
   */
  public void setStatusSkippingTransitionTest(final QueryStatus newStatus) {
    this.status = newStatus;
  }

  public synchronized void setStatus(final QueryStatus newStatus) throws LensException {
    validateTransition(newStatus);
    log.info("Updating status of {} from {} to {}", getQueryHandle(), this.status, newStatus);
    this.status = newStatus;
  }

  /**
   * Update status from selected driver
   *
   * @param statusUpdateRetryHandler The exponential retry handler
   *
   * @throws LensException Throws exception if update from driver has failed.
   */
  public synchronized void updateDriverStatus(BackOffRetryHandler statusUpdateRetryHandler)
    throws LensException {
    if (statusUpdateRetryHandler.canTryOpNow(statusUpdateFailures)) {
      try {
        getSelectedDriver().updateStatus(this);
        statusUpdateFailures.clear();
      } catch (LensException exc) {
        if (LensUtil.isSocketException(exc)) {
          statusUpdateFailures.updateFailure();
          if (!statusUpdateRetryHandler.hasExhaustedRetries(statusUpdateFailures)) {
            // retries are not exhausted, so failure is ignored and update will be tried later
            log.warn("Exception during update status from driver and update will be tried again at {}",
              statusUpdateRetryHandler.getOperationNextTime(statusUpdateFailures), exc);
            return;
          }
        }
        throw exc;
      }
    }
  }

  public String getResultHeader() {
    return getConf().get(LensConfConstants.QUERY_OUTPUT_HEADER);
  }

  public String getResultFooter() {
    return getConf().get(LensConfConstants.QUERY_OUTPUT_FOOTER);
  }

  public String getResultEncoding() {
    return conf.get(LensConfConstants.QUERY_OUTPUT_CHARSET_ENCODING, LensConfConstants.DEFAULT_OUTPUT_CHARSET_ENCODING);
  }

  public String getOuptutFileExtn() {
    return conf.get(LensConfConstants.QUERY_OUTPUT_FILE_EXTN, LensConfConstants.DEFAULT_OUTPUT_FILE_EXTN);
  }

  public boolean getCompressOutput() {
    return conf.getBoolean(LensConfConstants.QUERY_OUTPUT_ENABLE_COMPRESSION,
      LensConfConstants.DEFAULT_OUTPUT_ENABLE_COMPRESSION);
  }

  public long getMaxResultSplitRows() {
    return conf.getLong(LensConfConstants.RESULT_SPLIT_MULTIPLE_MAX_ROWS,
      LensConfConstants.DEFAULT_RESULT_SPLIT_MULTIPLE_MAX_ROWS);
  }

  /**
   * Split result into multiple files.
   *
   * @return true, if successful
   */
  public boolean splitResultIntoMultipleFiles() {
    return conf.getBoolean(LensConfConstants.RESULT_SPLIT_INTO_MULTIPLE,
      LensConfConstants.DEFAULT_RESULT_SPLIT_INTO_MULTIPLE);
  }

  public String getClusterUser() {
    return conf.get(LensConfConstants.SESSION_CLUSTER_USER, getSubmittedUser());
  }


  /**
   * @return query handle string
   */
  @Override
  public String getLogHandle() {
    return getQueryHandleString();
  }

  public String getQueryHandleString() {
    return queryHandle.getHandleIdString();
  }

  public void validateTransition(final QueryStatus newStatus) throws LensException {
    if (!this.status.isValidTransition(newStatus.getStatus())) {
      throw new LensException("Invalid state transition:from[" + this.status.getStatus() + " to "
        + newStatus.getStatus() + "]");
    }
  }

  public boolean finished() {
    return this.status.finished();
  }

  public boolean successful() {
    return this.status.successful();
  }
  public boolean executed() {
    return this.status.executed();
  }

  public boolean launched() {
    return this.status.launched();
  }

  public boolean running() {
    return this.status.running();
  }

  public boolean queued() {
    return this.status.queued();
  }

  public ImmutableSet<QueryLaunchingConstraint> getSelectedDriverQueryConstraints() {
    return getSelectedDriver().getQueryConstraints();
  }

  public synchronized void registerDriverResult(LensResultSet result) throws LensException {
    if (isDriverResultRegistered) {
      return; //already registered
    }
    log.info("Registering driver resultset for query {}", getQueryHandleString());
    this.isDriverResultRegistered = true;

    /*
     *  Check if results needs to be streamed to client in which case driver result needs to be wrapped in
     *  PartiallyFetchedInMemoryResultSet
     *
     *  1. Driver Result should be of type InMemory (for streaming) as only such results can be streamed fast
     *  2. Query result should be server persistent. Only in this case, an early streaming is required by client
     *  that starts even before server level result persistence/formatting finishes.
     *  3. When execiteTimeout is 0, it refers to an async query. In this case streaming result does not make sense
     *  4. PREFETCH_INMEMORY_RESULTSET = true, implies client intends to get early streamed result
     *  5. rowsToPreFetch should be > 0
     */
    if (isPersistent && executeTimeoutMillis > 0
      && result instanceof InMemoryResultSet
      && conf.getBoolean(PREFETCH_INMEMORY_RESULTSET, DEFAULT_PREFETCH_INMEMORY_RESULTSET)) {
      int rowsToPreFetch = conf.getInt(PREFETCH_INMEMORY_RESULTSET_ROWS, DEFAULT_PREFETCH_INMEMORY_RESULTSET_ROWS);
      if (rowsToPreFetch > 0) {
        long executeTimeOutTime = submissionTime + executeTimeoutMillis;
        if (System.currentTimeMillis() < executeTimeOutTime) {
          this.driverResult = new PartiallyFetchedInMemoryResultSet((InMemoryResultSet) result, rowsToPreFetch);
          return;
        } else {
          log.info("Skipping creation of PartiallyFetchedInMemoryResultSet as the query {} has already timed out",
            getQueryHandleString());
        }
      }
    }
    this.driverResult = result;
  }
  public void setDriverStatus(DriverQueryStatus.DriverQueryState state, String message) {
    if (getDriverStatus().getState().getOrder() > state.getOrder()) {
      log.info("current driver status: {}, ignoring transition request to {}", getDriverStatus().getState(), state);
      return;
    }
    switch (state) {
    case NEW:
    case INITIALIZED:
    case PENDING:
      getDriverStatus().setProgress(0.0);
    case RUNNING:
      if (getDriverStatus().getDriverStartTime() == null || getDriverStatus().getDriverStartTime() <= 0) {
        getDriverStatus().setDriverStartTime(System.currentTimeMillis());
      }
      break;
    case SUCCESSFUL:
    case FAILED:
    case CANCELED:
      getDriverStatus().setProgress(1.0);
      if (getDriverStatus().getDriverFinishTime() == null || getDriverStatus().getDriverFinishTime() <= 0) {
        getDriverStatus().setDriverFinishTime(System.currentTimeMillis());
      }
      break;
    default:
      break;
    }
    if (message != null) {
      if (state == DriverQueryStatus.DriverQueryState.FAILED) {
        getDriverStatus().setErrorMessage(message);
      } else {
        getDriverStatus().setStatusMessage(message);
      }
    }
    if (getDriverStatus().getStatusMessage() == null) {
      getDriverStatus().setStatusMessage("Query " + getQueryHandleString() + " " + state.name().toLowerCase());
    }
    getDriverStatus().setState(state);

    for (QueryDriverStatusUpdateListener listener : this.driverStatusUpdateListeners) {
      listener.onDriverStatusUpdated(getQueryHandle(), getDriverStatus());
    }
  }

  public String toString() {
    return queryHandle + ":" + this.status;
  }

  public void setDriverStatus(DriverQueryStatus.DriverQueryState state) {
    setDriverStatus(state, null);
  }


  public void registerStatusUpdateListener(QueryDriverStatusUpdateListener driverStatusUpdateListener) {
    this.driverStatusUpdateListeners.add(driverStatusUpdateListener);
  }

  @Override
  public long getLastFailedTime() {
    if (getFailCount() == 0) {
      return 0;
    }
    return getFailedAttempts().get(getFailedAttempts().size() - 1).getDriverFinishTime();
  }

  @Override
  public int getFailCount() {
    return getFailedAttempts().size();
  }

  public BackOffRetryHandler<QueryContext> getRetryPolicy() {
    return driverRetryPolicy != null ? driverRetryPolicy : serverRetryPolicy;
  }

  public void extractFailedAttempt() {
    extractFailedAttempt(getSelectedDriver());
  }

  public void extractFailedAttempt(LensDriver selectedDriver) {
    failedAttempts.add(new FailedAttempt(selectedDriver.getFullyQualifiedName(), getDriverStatus().getProgress(),
      getDriverStatus().getProgressMessage(), getDriverStatus().getErrorMessage(),
      getDriverStatus().getDriverStartTime(), getDriverStatus().getDriverFinishTime()));
    getDriverStatus().clear();
  }

  public boolean hasTimedout() {
    if (status.running()) {
      long runtimeMillis = System.currentTimeMillis() - launchTime;
      long timeoutMillis = getSelectedDriverConf().getInt(QUERY_TIMEOUT_MILLIS, DEFAULT_QUERY_TIMEOUT_MILLIS);
      return runtimeMillis > timeoutMillis;
    }
    return false;
  }
}