/**
 * 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.hadoop.hive.ql.udf.generic;

import java.util.ArrayList;
import java.util.List;

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.serde2.objectinspector.ListObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector.Category;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;

@Description(name ="inline", value= "_FUNC_( ARRAY( STRUCT()[,STRUCT()] "
+ "- explodes and array and struct into a table")
public class GenericUDTFInline extends GenericUDTF {

  private transient ListObjectInspector li;

  public GenericUDTFInline(){
  }

  @Override
  public StructObjectInspector initialize(ObjectInspector[] ois) throws UDFArgumentException {
    //There should be one argument that is a array of struct
    if (ois.length!=1){
      throw new UDFArgumentException("UDF tables only one argument");
    }
    if (ois[0].getCategory()!= Category.LIST){
      throw new UDFArgumentException("Top level object must be an array but "
              + "was "+ois[0].getTypeName());
    }
    li = (ListObjectInspector) ois[0];
    ObjectInspector sub=li.getListElementObjectInspector();
    if (sub.getCategory() != Category.STRUCT){
      throw new UDFArgumentException("The sub element must be struct, but was "+sub.getTypeName());
    }
    return (StructObjectInspector) sub;
  }

  @Override
  public void process(Object[] os) throws HiveException {
    List<?> list = li.getList(os[0]);
    if (list != null && !list.isEmpty()) {
      for (Object row : list.toArray()) {
        forward(row);
      }
    }
  }

  @Override
  public void close() throws HiveException {
  }

  @Override
  public String toString() {
    return "inline";
  }
}