/*
 * 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.aggregation.impl;

import org.apache.iotdb.db.query.aggregation.AggregateResult;
import org.apache.iotdb.db.query.aggregation.AggregationType;
import org.apache.iotdb.db.query.reader.series.IReaderByTimestamp;
import org.apache.iotdb.db.utils.ValueIterator;
import org.apache.iotdb.tsfile.file.metadata.enums.TSDataType;
import org.apache.iotdb.tsfile.file.metadata.statistics.Statistics;
import org.apache.iotdb.tsfile.read.common.IBatchDataIterator;

import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.function.Predicate;

public class MinTimeAggrResult extends AggregateResult {

  public MinTimeAggrResult() {
    super(TSDataType.INT64, AggregationType.MIN_TIME);
    reset();
  }

  @Override
  public Long getResult() {
    return hasCandidateResult() ? getLongValue() : null;
  }

  @Override
  public void updateResultFromStatistics(Statistics statistics) {
    if (hasFinalResult()) {
      return;
    }
    long time = statistics.getStartTime();
    setValue(time);
  }

  @Override
  public void updateResultFromPageData(IBatchDataIterator batchIterator) {
    updateResultFromPageData(batchIterator, time -> false);
  }

  @Override
  public void updateResultFromPageData(
      IBatchDataIterator batchIterator, Predicate<Long> boundPredicate) {
    if (hasFinalResult()) {
      return;
    }
    if (batchIterator.hasNext(boundPredicate)
        && !boundPredicate.test(batchIterator.currentTime())) {
      setLongValue(batchIterator.currentTime());
    }
  }

  @Override
  public void updateResultUsingTimestamps(
      long[] timestamps, int length, IReaderByTimestamp dataReader) throws IOException {
    if (hasFinalResult()) {
      return;
    }
    int currentPos = 0;
    long[] timesForFirstValue = new long[TIME_LENGTH_FOR_FIRST_VALUE];
    while (currentPos < length) {
      int timeLength = Math.min(length - currentPos, TIME_LENGTH_FOR_FIRST_VALUE);
      System.arraycopy(timestamps, currentPos, timesForFirstValue, 0, timeLength);
      Object[] values = dataReader.getValuesInTimestamps(timesForFirstValue, timeLength);
      for (int i = 0; i < timeLength; i++) {
        if (values[i] != null) {
          setLongValue(timesForFirstValue[i]);
          return;
        }
      }
      currentPos += timeLength;
    }
  }

  @Override
  public void updateResultUsingValues(long[] timestamps, int length, ValueIterator valueIterator) {
    if (hasFinalResult()) {
      return;
    }
    if (valueIterator.hasNext()) {
      setLongValue(timestamps[valueIterator.getCurPos()]);
    }
  }

  @Override
  public boolean hasFinalResult() {
    return hasCandidateResult;
  }

  @Override
  public void merge(AggregateResult another) {
    MinTimeAggrResult anotherMinTime = (MinTimeAggrResult) another;
    if (!hasCandidateResult() && anotherMinTime.hasCandidateResult()) {
      setLongValue(anotherMinTime.getResult());
      return;
    }
    if (hasCandidateResult()
        && anotherMinTime.hasCandidateResult()
        && getResult() > anotherMinTime.getResult()) {
      setLongValue(anotherMinTime.getResult());
    }
  }

  @Override
  protected void deserializeSpecificFields(ByteBuffer buffer) {}

  @Override
  protected void serializeSpecificFields(OutputStream outputStream) {}
}
