/*
 * 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.spark.sql.vectorized;

import java.util.*;

import org.apache.spark.annotation.Evolving;
import org.apache.spark.sql.catalyst.InternalRow;
import org.apache.spark.sql.catalyst.expressions.GenericInternalRow;
import org.apache.spark.sql.types.*;
import org.apache.spark.unsafe.types.CalendarInterval;
import org.apache.spark.unsafe.types.UTF8String;

/**
 * This class wraps multiple ColumnVectors as a row-wise table. It provides a row view of this
 * batch so that Spark can access the data row by row. Instance of it is meant to be reused during
 * the entire data loading process.
 */
@Evolving
public final class ColumnarBatch {
  private int numRows;
  private final ColumnVector[] columns;

  // Staging row returned from `getRow`.
  private final ColumnarBatchRow row;

  /**
   * Called to close all the columns in this batch. It is not valid to access the data after
   * calling this. This must be called at the end to clean up memory allocations.
   */
  public void close() {
    for (ColumnVector c: columns) {
      c.close();
    }
  }

  /**
   * Returns an iterator over the rows in this batch.
   */
  public Iterator<InternalRow> rowIterator() {
    final int maxRows = numRows;
    final ColumnarBatchRow row = new ColumnarBatchRow(columns);
    return new Iterator<InternalRow>() {
      int rowId = 0;

      @Override
      public boolean hasNext() {
        return rowId < maxRows;
      }

      @Override
      public InternalRow next() {
        if (rowId >= maxRows) {
          throw new NoSuchElementException();
        }
        row.rowId = rowId++;
        return row;
      }

      @Override
      public void remove() {
        throw new UnsupportedOperationException();
      }
    };
  }

  /**
   * Sets the number of rows in this batch.
   */
  public void setNumRows(int numRows) {
    this.numRows = numRows;
  }

  /**
   * Returns the number of columns that make up this batch.
   */
  public int numCols() { return columns.length; }

  /**
   * Returns the number of rows for read, including filtered rows.
   */
  public int numRows() { return numRows; }

  /**
   * Returns the column at `ordinal`.
   */
  public ColumnVector column(int ordinal) { return columns[ordinal]; }

  /**
   * Returns the row in this batch at `rowId`. Returned row is reused across calls.
   */
  public InternalRow getRow(int rowId) {
    assert(rowId >= 0 && rowId < numRows);
    row.rowId = rowId;
    return row;
  }

  public ColumnarBatch(ColumnVector[] columns) {
    this.columns = columns;
    this.row = new ColumnarBatchRow(columns);
  }
}

/**
 * An internal class, which wraps an array of {@link ColumnVector} and provides a row view.
 */
class ColumnarBatchRow extends InternalRow {
  public int rowId;
  private final ColumnVector[] columns;

  ColumnarBatchRow(ColumnVector[] columns) {
    this.columns = columns;
  }

  @Override
  public int numFields() { return columns.length; }

  @Override
  public InternalRow copy() {
    GenericInternalRow row = new GenericInternalRow(columns.length);
    for (int i = 0; i < numFields(); i++) {
      if (isNullAt(i)) {
        row.setNullAt(i);
      } else {
        DataType dt = columns[i].dataType();
        if (dt instanceof BooleanType) {
          row.setBoolean(i, getBoolean(i));
        } else if (dt instanceof ByteType) {
          row.setByte(i, getByte(i));
        } else if (dt instanceof ShortType) {
          row.setShort(i, getShort(i));
        } else if (dt instanceof IntegerType) {
          row.setInt(i, getInt(i));
        } else if (dt instanceof LongType) {
          row.setLong(i, getLong(i));
        } else if (dt instanceof FloatType) {
          row.setFloat(i, getFloat(i));
        } else if (dt instanceof DoubleType) {
          row.setDouble(i, getDouble(i));
        } else if (dt instanceof StringType) {
          row.update(i, getUTF8String(i).copy());
        } else if (dt instanceof BinaryType) {
          row.update(i, getBinary(i));
        } else if (dt instanceof DecimalType) {
          DecimalType t = (DecimalType)dt;
          row.setDecimal(i, getDecimal(i, t.precision(), t.scale()), t.precision());
        } else if (dt instanceof DateType) {
          row.setInt(i, getInt(i));
        } else if (dt instanceof TimestampType) {
          row.setLong(i, getLong(i));
        } else {
          throw new RuntimeException("Not implemented. " + dt);
        }
      }
    }
    return row;
  }

  @Override
  public boolean anyNull() {
    throw new UnsupportedOperationException();
  }

  @Override
  public boolean isNullAt(int ordinal) { return columns[ordinal].isNullAt(rowId); }

  @Override
  public boolean getBoolean(int ordinal) { return columns[ordinal].getBoolean(rowId); }

  @Override
  public byte getByte(int ordinal) { return columns[ordinal].getByte(rowId); }

  @Override
  public short getShort(int ordinal) { return columns[ordinal].getShort(rowId); }

  @Override
  public int getInt(int ordinal) { return columns[ordinal].getInt(rowId); }

  @Override
  public long getLong(int ordinal) { return columns[ordinal].getLong(rowId); }

  @Override
  public float getFloat(int ordinal) { return columns[ordinal].getFloat(rowId); }

  @Override
  public double getDouble(int ordinal) { return columns[ordinal].getDouble(rowId); }

  @Override
  public Decimal getDecimal(int ordinal, int precision, int scale) {
    return columns[ordinal].getDecimal(rowId, precision, scale);
  }

  @Override
  public UTF8String getUTF8String(int ordinal) {
    return columns[ordinal].getUTF8String(rowId);
  }

  @Override
  public byte[] getBinary(int ordinal) {
    return columns[ordinal].getBinary(rowId);
  }

  @Override
  public CalendarInterval getInterval(int ordinal) {
    return columns[ordinal].getInterval(rowId);
  }

  @Override
  public ColumnarRow getStruct(int ordinal, int numFields) {
    return columns[ordinal].getStruct(rowId);
  }

  @Override
  public ColumnarArray getArray(int ordinal) {
    return columns[ordinal].getArray(rowId);
  }

  @Override
  public ColumnarMap getMap(int ordinal) {
    return columns[ordinal].getMap(rowId);
  }

  @Override
  public Object get(int ordinal, DataType dataType) {
    if (dataType instanceof BooleanType) {
      return getBoolean(ordinal);
    } else if (dataType instanceof ByteType) {
      return getByte(ordinal);
    } else if (dataType instanceof ShortType) {
      return getShort(ordinal);
    } else if (dataType instanceof IntegerType) {
      return getInt(ordinal);
    } else if (dataType instanceof LongType) {
      return getLong(ordinal);
    } else if (dataType instanceof FloatType) {
      return getFloat(ordinal);
    } else if (dataType instanceof DoubleType) {
      return getDouble(ordinal);
    } else if (dataType instanceof StringType) {
      return getUTF8String(ordinal);
    } else if (dataType instanceof BinaryType) {
      return getBinary(ordinal);
    } else if (dataType instanceof DecimalType) {
      DecimalType t = (DecimalType) dataType;
      return getDecimal(ordinal, t.precision(), t.scale());
    } else if (dataType instanceof DateType) {
      return getInt(ordinal);
    } else if (dataType instanceof TimestampType) {
      return getLong(ordinal);
    } else if (dataType instanceof ArrayType) {
      return getArray(ordinal);
    } else if (dataType instanceof StructType) {
      return getStruct(ordinal, ((StructType)dataType).fields().length);
    } else if (dataType instanceof MapType) {
      return getMap(ordinal);
    } else {
      throw new UnsupportedOperationException("Datatype not supported " + dataType);
    }
  }

  @Override
  public void update(int ordinal, Object value) { throw new UnsupportedOperationException(); }

  @Override
  public void setNullAt(int ordinal) { throw new UnsupportedOperationException(); }
}
