/*
 * 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.datasketches.hive.frequencies;

import org.apache.datasketches.ArrayOfItemsSerDe;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFParameterInfo;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;

/**
 * This is a generic implementation to be specialized in subclasses
 * @param <T> type of item
 */
public abstract class UnionItemsSketchUDAF<T> extends AbstractGenericUDAFResolver {

  @Override
  public GenericUDAFEvaluator getEvaluator(final GenericUDAFParameterInfo info) throws SemanticException {
    final ObjectInspector[] inspectors = info.getParameterObjectInspectors();
    if (inspectors.length != 1) {
      throw new UDFArgumentException("One argument expected");
    }
    if (inspectors[0].getCategory() != ObjectInspector.Category.PRIMITIVE) {
      throw new UDFArgumentTypeException(0, "Primitive argument expected, but "
          + inspectors[0].getTypeName() + " was recieved");
    }
    final PrimitiveObjectInspector inspector = (PrimitiveObjectInspector) inspectors[0];
    if (inspector.getPrimitiveCategory() != PrimitiveObjectInspector.PrimitiveCategory.BINARY) {
      throw new UDFArgumentTypeException(0, "Binary argument expected, but "
          + inspector.getPrimitiveCategory().name() + " was received");
    }
    return createEvaluator();
  }

  abstract GenericUDAFEvaluator createEvaluator();

  @SuppressWarnings("javadoc")
  public static class UnionItemsSketchEvaluator<T> extends ItemsEvaluator<T> {

    UnionItemsSketchEvaluator(final ArrayOfItemsSerDe<T> serDe) {
      super(serDe);
    }

    @SuppressWarnings("deprecation")
    @Override
    public void iterate(final AggregationBuffer buf, final Object[] data) throws HiveException {
      merge(buf, data[0]);
    }

  }

}