/**
 * 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 org.apache.commons.lang.StringUtils;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorConverter.TextConverter;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.io.Text;

public abstract class GenericUDFBaseTrim extends GenericUDF {
  private transient TextConverter converter;
  private Text result = new Text();
  private String udfName;

  public GenericUDFBaseTrim(String _udfName) {
    this.udfName = _udfName;
  }

  @Override
  public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {
    if (arguments.length != 1) {
      throw new UDFArgumentException(udfName + " requires one value argument. Found :"
        + arguments.length);
    }
    PrimitiveObjectInspector argumentOI;
    if(arguments[0] instanceof PrimitiveObjectInspector) {
      argumentOI = (PrimitiveObjectInspector) arguments[0];
    } else {
      throw new UDFArgumentException(udfName + " takes only primitive types. found "
        + arguments[0].getTypeName());
    }
    switch (argumentOI.getPrimitiveCategory()) {
    case STRING:
    case CHAR:
    case VARCHAR:
      break;
    default:
      throw new UDFArgumentException(udfName + " takes only STRING/CHAR/VARCHAR types. Found "
        + argumentOI.getPrimitiveCategory());
    }
    converter = new TextConverter(argumentOI);
    return PrimitiveObjectInspectorFactory.writableStringObjectInspector;
  }

  @Override
  public Object evaluate(DeferredObject[] arguments) throws HiveException {
    Object valObject = arguments[0].get();
    if (valObject == null) {
      return null;
    }
    String val = ((Text) converter.convert(valObject)).toString();
    if (val == null) {
      return null;
    }
    result.set(performOp(val.toString()));
    return result;
  }

  @Override
  public String getDisplayString(String[] children) {
    return getStandardDisplayString(udfName, children);
  }

  protected abstract String performOp(String val);

}