content: /*
   * 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.carbondata.presto.readers;
  
  import java.math.BigDecimal;
  import java.math.BigInteger;
  
  import static java.math.RoundingMode.HALF_UP;
  
  import org.apache.carbondata.core.metadata.datatype.DataType;
  import org.apache.carbondata.core.scan.result.vector.impl.CarbonColumnVectorImpl;
  
  import com.facebook.presto.spi.block.Block;
  import com.facebook.presto.spi.block.BlockBuilder;
  import com.facebook.presto.spi.type.DecimalType;
  import com.facebook.presto.spi.type.Decimals;
  import com.facebook.presto.spi.type.Type;
  import io.airlift.slice.Slice;
  
  import static com.facebook.presto.spi.type.Decimals.encodeUnscaledValue;
  import static com.facebook.presto.spi.type.Decimals.isShortDecimal;
  import static com.facebook.presto.spi.type.Decimals.rescale;
  import static com.google.common.base.Preconditions.checkArgument;
  import static com.google.common.base.Preconditions.checkState;
  import static io.airlift.slice.Slices.utf8Slice;
  
  /**
   * Reader for DecimalValues
   */
  public class DecimalSliceStreamReader extends CarbonColumnVectorImpl
      implements PrestoVectorBlockBuilder {
  
    private final char[] buffer = new char[100];
    protected int batchSize;
    protected Type type;
    protected BlockBuilder builder;
  
    public DecimalSliceStreamReader(int batchSize, DataType dataType,
        org.apache.carbondata.core.metadata.datatype.DecimalType decimalDataType) {
      super(batchSize, dataType);
      this.type =
          DecimalType.createDecimalType(decimalDataType.getPrecision(), decimalDataType.getScale());
      this.batchSize = batchSize;
      this.builder = type.createBlockBuilder(null, batchSize);
    }
  
    @Override
    public Block buildBlock() {
      return builder.build();
    }
  
    @Override
    public void setBatchSize(int batchSize) {
      this.batchSize = batchSize;
    }
  
    @Override
    public void putDecimal(int rowId, BigDecimal value, int precision) {
      decimalBlockWriter(value);
    }
  
    @Override
    public void putDecimals(int rowId, int count, BigDecimal value, int precision) {
      for (int i = 0; i < count; i++) {
        putDecimal(rowId++, value, precision);
      }
    }
  
    @Override
    public void putNulls(int rowId, int count) {
      for (int i = 0; i < count; i++) {
        builder.appendNull();
      }
    }
  
    @Override
    public void putNull(int rowId) {
      builder.appendNull();
    }
  
    @Override
    public void reset() {
      builder = type.createBlockBuilder(null, batchSize);
    }
  
    private void decimalBlockWriter(BigDecimal value) {
      if (isShortDecimal(type)) {
        long rescaledDecimal = Decimals.rescale(value.unscaledValue().longValue(), value.scale(),
            ((DecimalType) type).getScale());
        type.writeLong(builder, rescaledDecimal);
      } else {
        Slice slice = getSlice(value, type);
        type.writeSlice(builder, parseSlice((DecimalType) type, slice, slice.length()));
      }
    }
  
    private Slice getSlice(Object value, Type type) {
      if (type instanceof DecimalType) {
        DecimalType actual = (DecimalType) type;
        BigDecimal bigDecimalValue = (BigDecimal) value;
        if (isShortDecimal(type)) {
          return utf8Slice(value.toString());
        } else {
          if (bigDecimalValue.scale() > actual.getScale()) {
            BigInteger unscaledDecimal =
                rescale(bigDecimalValue.unscaledValue(), bigDecimalValue.scale(),
                    bigDecimalValue.scale());
            Slice decimalSlice = Decimals.encodeUnscaledValue(unscaledDecimal);
            return utf8Slice(Decimals.toString(decimalSlice, actual.getScale()));
          } else {
            BigInteger unscaledDecimal =
                rescale(bigDecimalValue.unscaledValue(), bigDecimalValue.scale(), actual.getScale());
            Slice decimalSlice = Decimals.encodeUnscaledValue(unscaledDecimal);
            return utf8Slice(Decimals.toString(decimalSlice, actual.getScale()));
          }
        }
      } else {
        return utf8Slice(value.toString());
      }
    }
  
    private Slice parseSlice(DecimalType type, Slice slice, int length) {
      BigDecimal decimal = parseBigDecimal(type, slice, length);
      return encodeUnscaledValue(decimal.unscaledValue());
    }
  
    private BigDecimal parseBigDecimal(DecimalType type, Slice slice, int length) {
      int offset = 0;
      checkArgument(length < buffer.length);
      for (int i = 0; i < length; i++) {
        buffer[i] = (char) slice.getByte(offset + i);
      }
      BigDecimal decimal = new BigDecimal(buffer, 0, length);
      checkState(decimal.scale() <= type.getScale(),
          "Read decimal value scale larger than column scale");
      decimal = decimal.setScale(type.getScale(), HALF_UP);
      checkState(decimal.precision() <= type.getPrecision(),
          "Read decimal precision larger than column precision");
      return decimal;
    }
  
    @Override
    public void putObject(int rowId, Object value) {
      if (value == null) {
        putNull(rowId);
      } else {
        decimalBlockWriter((BigDecimal) value);
      }
    }
  }
  