/*
 * 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.queryengine.execution.operator.source.relational.aggregation.grouped.array;

import org.apache.tsfile.utils.TsPrimitiveType;

import java.util.HashMap;

import static org.apache.tsfile.utils.RamUsageEstimator.shallowSizeOfInstance;
import static org.apache.tsfile.utils.RamUsageEstimator.sizeOfObject;

public final class MapBigArray {
  private static final long INSTANCE_SIZE = shallowSizeOfInstance(MapBigArray.class);
  private final ObjectBigArray<HashMap<TsPrimitiveType, Long>> array;
  private long sizeOfMaps;

  public MapBigArray() {
    array = new ObjectBigArray<>();
  }

  /** Returns the size of this big array in bytes. */
  public long sizeOf() {
    return INSTANCE_SIZE + array.sizeOf() + sizeOfMaps;
  }

  /**
   * Returns the element of this big array at specified index.
   *
   * @param index a position in this big array.
   * @return the element of this big array at the specified position.
   */
  public HashMap<TsPrimitiveType, Long> get(long index) {
    HashMap<TsPrimitiveType, Long> result = array.get(index);
    if (result == null) {
      result = new HashMap<>();
      array.set(index, result);
    }
    return result;
  }

  /**
   * Sets the element of this big array at specified index.
   *
   * @param index a position in this big array.
   */
  public void set(long index, HashMap<TsPrimitiveType, Long> value) {
    updateRetainedSize(index, value);
    array.set(index, value);
  }

  /**
   * Ensures this big array is at least the specified length. If the array is smaller, segments are
   * added until the array is larger then the specified length.
   */
  public void ensureCapacity(long length) {
    array.ensureCapacity(length);
  }

  private void updateRetainedSize(long index, HashMap<TsPrimitiveType, Long> value) {
    HashMap<TsPrimitiveType, Long> currentValue = array.get(index);
    if (currentValue != null) {
      sizeOfMaps -= sizeOfObject(currentValue);
    }
    if (value != null) {
      sizeOfMaps += sizeOfObject(value);
    }
  }

  public void reset() {
    array.forEach(
        v -> {
          if (v != null) {
            v.clear();
          }
        });
  }
}
