/*
 * 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.operator.process.join.merge;

import org.apache.iotdb.db.mpp.plan.planner.plan.parameter.InputLocation;
import org.apache.iotdb.tsfile.read.common.block.TsBlock;
import org.apache.iotdb.tsfile.read.common.block.column.Column;
import org.apache.iotdb.tsfile.read.common.block.column.ColumnBuilder;
import org.apache.iotdb.tsfile.read.common.block.column.TimeColumn;
import org.apache.iotdb.tsfile.read.common.block.column.TimeColumnBuilder;

/** only has one input column */
public class SingleColumnMerger implements ColumnMerger {

  private final InputLocation location;

  private final TimeComparator comparator;

  public SingleColumnMerger(InputLocation location, TimeComparator comparator) {
    this.location = location;
    this.comparator = comparator;
  }

  @Override
  public void mergeColumn(
      TsBlock[] inputTsBlocks,
      int[] inputIndex,
      int[] updatedInputIndex,
      TimeColumnBuilder timeBuilder,
      long currentEndTime,
      ColumnBuilder columnBuilder) {

    mergeOneColumn(
        inputTsBlocks,
        inputIndex,
        updatedInputIndex,
        timeBuilder,
        currentEndTime,
        columnBuilder,
        location,
        comparator);
  }

  public static void mergeOneColumn(
      TsBlock[] inputTsBlocks,
      int[] inputIndex,
      int[] updatedInputIndex,
      TimeColumnBuilder timeBuilder,
      long currentEndTime,
      ColumnBuilder columnBuilder,
      InputLocation location,
      TimeComparator comparator) {
    int tsBlockIndex = location.getTsBlockIndex();
    int columnIndex = location.getValueColumnIndex();

    int rowCount = timeBuilder.getPositionCount();
    int index = inputIndex[tsBlockIndex];
    // input column is empty or current time of input column is already larger than currentEndTime
    // just appendNull rowCount null
    if (ColumnMerger.empty(tsBlockIndex, inputTsBlocks, inputIndex)
        || !comparator.satisfyCurEndTime(
            inputTsBlocks[tsBlockIndex].getTimeByIndex(index), currentEndTime)) {
      columnBuilder.appendNull(rowCount);
    } else {
      // read from input column and write it into columnBuilder
      TimeColumn timeColumn = inputTsBlocks[tsBlockIndex].getTimeColumn();
      Column valueColumn = inputTsBlocks[tsBlockIndex].getColumn(columnIndex);
      for (int i = 0; i < rowCount; i++) {
        // current index reaches the size of input column or current time of input column is already
        // larger than currentEndTime, use null column to fill the remaining
        if (timeColumn.getPositionCount() == index
            || !comparator.satisfyCurEndTime(
                inputTsBlocks[tsBlockIndex].getTimeByIndex(index), currentEndTime)) {
          columnBuilder.appendNull(rowCount - i);
          break;
        }
        // current time of input column is equal to result row's time
        if (timeColumn.getLong(index) == timeBuilder.getTime(i)) {
          // if input column's value at index is null, append a null value
          if (valueColumn.isNull(index)) {
            columnBuilder.appendNull();
          } else {
            // if input column's value at index is not null, append the value
            columnBuilder.write(valueColumn, index);
          }
          // increase the index
          index++;
        } else {
          // otherwise, append a null
          columnBuilder.appendNull();
        }
      }
    }
    // update the index after merging
    updatedInputIndex[tsBlockIndex] = index;
  }

  @Override
  public void mergeColumn(
      TsBlock[] inputTsBlocks,
      int[] inputIndex,
      int[] updatedInputIndex,
      long currentTime,
      ColumnBuilder columnBuilder) {
    mergeOneColumn(
        inputTsBlocks, inputIndex, updatedInputIndex, currentTime, columnBuilder, location);
  }

  public static void mergeOneColumn(
      TsBlock[] inputTsBlocks,
      int[] inputIndex,
      int[] updatedInputIndex,
      long currentTime,
      ColumnBuilder columnBuilder,
      InputLocation location) {
    int tsBlockIndex = location.getTsBlockIndex();
    int columnIndex = location.getValueColumnIndex();

    int index = inputIndex[tsBlockIndex];
    // input column is empty or current time of input column is already larger than currentEndTime
    // just appendNull
    if (ColumnMerger.empty(tsBlockIndex, inputTsBlocks, inputIndex)
        || inputTsBlocks[tsBlockIndex].getTimeByIndex(index) != currentTime) {
      columnBuilder.appendNull();
    } else {
      // read from input column and write it into columnBuilder
      Column valueColumn = inputTsBlocks[tsBlockIndex].getColumn(columnIndex);

      if (valueColumn.isNull(index)) {
        columnBuilder.appendNull();
      } else {
        columnBuilder.write(valueColumn, index);
      }
      index++;
    }
    // update the index after merging
    updatedInputIndex[tsBlockIndex] = index;
  }
}
