/*
 * 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.source;

import org.apache.iotdb.commons.path.AlignedPath;
import org.apache.iotdb.db.mpp.execution.operator.OperatorContext;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanNodeId;
import org.apache.iotdb.db.mpp.plan.planner.plan.parameter.SeriesScanOptions;
import org.apache.iotdb.db.mpp.plan.statement.component.Ordering;
import org.apache.iotdb.tsfile.common.conf.TSFileDescriptor;
import org.apache.iotdb.tsfile.read.common.block.TsBlock;
import org.apache.iotdb.tsfile.read.common.block.TsBlockBuilder;
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;

import java.io.IOException;
import java.util.concurrent.TimeUnit;

public class AlignedSeriesScanOperator extends AbstractDataSourceOperator {

  private final TsBlockBuilder builder;
  private final int valueColumnCount;
  private boolean finished = false;

  public AlignedSeriesScanOperator(
      OperatorContext context,
      PlanNodeId sourceId,
      AlignedPath seriesPath,
      Ordering scanOrder,
      SeriesScanOptions seriesScanOptions) {
    this.sourceId = sourceId;
    this.operatorContext = context;
    this.seriesScanUtil =
        new AlignedSeriesScanUtil(
            seriesPath, scanOrder, seriesScanOptions, context.getInstanceContext());
    // time + all value columns
    this.builder = new TsBlockBuilder(seriesScanUtil.getTsDataTypeList());
    this.valueColumnCount = seriesPath.getColumnNum();
    this.maxReturnSize =
        Math.min(
            maxReturnSize,
            (1L + valueColumnCount)
                * TSFileDescriptor.getInstance().getConfig().getPageSizeInByte());
  }

  @Override
  public TsBlock next() throws Exception {
    if (retainedTsBlock != null) {
      return getResultFromRetainedTsBlock();
    }
    resultTsBlock = builder.build();
    builder.reset();
    return checkTsBlockSizeAndGetResult();
  }

  @Override
  public boolean hasNext() throws Exception {
    if (retainedTsBlock != null) {
      return true;
    }
    try {

      // start stopwatch
      long maxRuntime = operatorContext.getMaxRunTime().roundTo(TimeUnit.NANOSECONDS);
      long start = System.nanoTime();

      // here use do-while to promise doing this at least once
      do {
        /*
         * consume page data firstly
         */
        if (readPageData()) {
          continue;
        }

        /*
         * consume chunk data secondly
         */
        if (readChunkData()) {
          continue;
        }

        /*
         * consume next file finally
         */
        if (readFileData()) {
          continue;
        }
        break;

      } while (System.nanoTime() - start < maxRuntime && !builder.isFull());

      finished = builder.isEmpty();

      return !finished;
    } catch (IOException e) {
      throw new RuntimeException("Error happened while scanning the file", e);
    }
  }

  @Override
  public boolean isFinished() throws Exception {
    return finished;
  }

  @Override
  public long calculateMaxPeekMemory() {
    return Math.max(
        maxReturnSize,
        (1L + valueColumnCount) * TSFileDescriptor.getInstance().getConfig().getPageSizeInByte());
  }

  @Override
  public long calculateMaxReturnSize() {
    return maxReturnSize;
  }

  @Override
  public long calculateRetainedSizeAfterCallingNext() {
    return calculateMaxPeekMemory() - calculateMaxReturnSize();
  }

  private boolean readFileData() throws IOException {
    while (seriesScanUtil.hasNextFile()) {
      if (readChunkData()) {
        return true;
      }
    }
    return false;
  }

  private boolean readChunkData() throws IOException {
    while (seriesScanUtil.hasNextChunk()) {
      if (readPageData()) {
        return true;
      }
    }
    return false;
  }

  private boolean readPageData() throws IOException {
    while (seriesScanUtil.hasNextPage()) {
      TsBlock tsBlock = seriesScanUtil.nextPage();
      if (!isEmpty(tsBlock)) {
        appendToBuilder(tsBlock);
        return true;
      }
    }
    return false;
  }

  private void appendToBuilder(TsBlock tsBlock) {
    int size = tsBlock.getPositionCount();
    TimeColumnBuilder timeColumnBuilder = builder.getTimeColumnBuilder();
    TimeColumn timeColumn = tsBlock.getTimeColumn();
    for (int i = 0; i < size; i++) {
      timeColumnBuilder.writeLong(timeColumn.getLong(i));
      builder.declarePosition();
    }
    for (int columnIndex = 0, columnSize = tsBlock.getValueColumnCount();
        columnIndex < columnSize;
        columnIndex++) {
      ColumnBuilder columnBuilder = builder.getColumnBuilder(columnIndex);
      Column column = tsBlock.getColumn(columnIndex);
      if (column.mayHaveNull()) {
        for (int i = 0; i < size; i++) {
          if (column.isNull(i)) {
            columnBuilder.appendNull();
          } else {
            columnBuilder.write(column, i);
          }
        }
      } else {
        for (int i = 0; i < size; i++) {
          columnBuilder.write(column, i);
        }
      }
    }
  }

  private boolean isEmpty(TsBlock tsBlock) {
    return tsBlock == null || tsBlock.isEmpty();
  }
}
