/*
 * 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.query.context;

import org.apache.iotdb.commons.path.AlignedPath;
import org.apache.iotdb.commons.path.PartialPath;
import org.apache.iotdb.commons.path.PatternTreeMap;
import org.apache.iotdb.db.engine.modification.Deletion;
import org.apache.iotdb.db.engine.modification.Modification;
import org.apache.iotdb.db.engine.modification.ModificationFile;
import org.apache.iotdb.db.metadata.path.PatternTreeMapFactory;
import org.apache.iotdb.db.metadata.path.PatternTreeMapFactory.ModsSerializer;
import org.apache.iotdb.tsfile.file.metadata.IChunkMetadata;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/** QueryContext contains the shared information with in a query. */
public class QueryContext {

  /**
   * The outer key is the path of a ModificationFile, the inner key in the name of a timeseries and
   * the value is the Modifications of a timeseries in this file.
   */
  private final Map<String, Map<String, List<Modification>>> filePathModCache =
      new ConcurrentHashMap<>();
  /**
   * The key is the path of a ModificationFile and the value is all Modifications in this file. We
   * use this field because each call of Modification.getModifications() return a copy of the
   * Modifications, and we do not want it to create multiple copies within a query.
   */
  private final Map<String, PatternTreeMap<Modification, ModsSerializer>> fileModCache =
      new HashMap<>();

  protected long queryId;

  private long queryTimeLowerBound = Long.MIN_VALUE;

  private boolean debug;

  /**
   * To reduce the cost of memory, we only keep the a certain size statement. For statement whose
   * length is over this, we keep its head and tail.
   */
  private static final int MAX_STATEMENT_LENGTH = 64;

  private long startTime;

  private String statement;

  private long timeout;

  private volatile boolean isInterrupted = false;

  public QueryContext() {}

  public QueryContext(long queryId) {
    this(queryId, false, System.currentTimeMillis(), "", 0);
  }

  /** Every time we generate the queryContext, register it to queryTimeManager. */
  public QueryContext(long queryId, boolean debug, long startTime, String statement, long timeout) {
    this.queryId = queryId;
    this.debug = debug;
    this.startTime = startTime;
    this.statement = statement;
    this.timeout = timeout;
  }

  /**
   * Find the modifications of timeseries 'path' in 'modFile'. If they are not in the cache, read
   * them from 'modFile' and put then into the cache.
   */
  public List<Modification> getPathModifications(ModificationFile modFile, PartialPath path) {
    // TODO change a way to do the existing check to avoid this IO call each time.

    // if the mods file does not exist, do not add it to the cache
    if (!modFile.exists()) {
      return Collections.emptyList();
    }
    Map<String, List<Modification>> fileModifications =
        filePathModCache.computeIfAbsent(modFile.getFilePath(), k -> new ConcurrentHashMap<>());
    return fileModifications.computeIfAbsent(
        path.getFullPath(),
        k -> {
          PatternTreeMap<Modification, ModsSerializer> allModifications =
              fileModCache.get(modFile.getFilePath());
          if (allModifications == null) {
            allModifications = PatternTreeMapFactory.getModsPatternTreeMap();
            for (Modification modification : modFile.getModifications()) {
              allModifications.append(modification.getPath(), modification);
            }
            fileModCache.put(modFile.getFilePath(), allModifications);
          }
          return sortAndMerge(allModifications.getOverlapped(path));
        });
  }

  private List<Modification> sortAndMerge(List<Modification> modifications) {
    modifications.sort(
        (o1, o2) -> {
          if (!o1.getType().equals(o2.getType())) {
            return o1.getType().compareTo(o2.getType());
          } else if (!o1.getPath().equals(o2.getPath())) {
            return o1.getPath().compareTo(o2.getPath());
          } else if (o1.getFileOffset() != o2.getFileOffset()) {
            return (int) (o1.getFileOffset() - o2.getFileOffset());
          } else {
            if (o1.getType() == Modification.Type.DELETION) {
              Deletion del1 = (Deletion) o1;
              Deletion del2 = (Deletion) o2;
              return del1.getTimeRange().compareTo(del2.getTimeRange());
            }
            throw new IllegalArgumentException();
          }
        });
    List<Modification> result = new ArrayList<>();
    if (!modifications.isEmpty()) {
      Deletion current = ((Deletion) modifications.get(0)).clone();
      for (int i = 1; i < modifications.size(); i++) {
        Deletion del = (Deletion) modifications.get(i);
        if (current.intersects(del)) {
          current.merge(del);
        } else {
          result.add(current);
          current = del.clone();
        }
      }
      result.add(current);
    }
    return result;
  }

  /**
   * Find the modifications of all aligned 'paths' in 'modFile'. If they are not in the cache, read
   * them from 'modFile' and put then into the cache.
   */
  public List<List<Modification>> getPathModifications(ModificationFile modFile, AlignedPath path) {
    int n = path.getMeasurementList().size();
    List<List<Modification>> ans = new ArrayList<>(n);
    for (int i = 0; i < n; i++) {
      ans.add(getPathModifications(modFile, path.getPathWithMeasurement(i)));
    }
    return ans;
  }

  public long getQueryId() {
    return queryId;
  }

  public boolean isDebug() {
    return debug;
  }

  public long getQueryTimeLowerBound() {
    return queryTimeLowerBound;
  }

  public void setQueryTimeLowerBound(long queryTimeLowerBound) {
    this.queryTimeLowerBound = queryTimeLowerBound;
  }

  public boolean chunkNotSatisfy(IChunkMetadata chunkMetaData) {
    return chunkMetaData.getEndTime() < queryTimeLowerBound;
  }

  public long getStartTime() {
    return startTime;
  }

  public String getStatement() {
    return statement;
  }

  public QueryContext setStartTime(long startTime) {
    this.startTime = startTime;
    return this;
  }

  public void getStatement(String statement) {
    this.statement = statement;
  }

  public long getTimeout() {
    return timeout;
  }

  public QueryContext setTimeout(long timeout) {
    this.timeout = timeout;
    return this;
  }

  public QueryContext setStatement(String statement) {
    if (statement.length() <= 64) {
      this.statement = statement;
    } else {
      this.statement =
          statement.substring(0, MAX_STATEMENT_LENGTH / 2)
              + "..."
              + statement.substring(statement.length() - MAX_STATEMENT_LENGTH / 2);
    }
    return this;
  }

  public void setInterrupted(boolean interrupted) {
    isInterrupted = interrupted;
  }

  public boolean isInterrupted() {
    return isInterrupted;
  }
}
