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'rapiddweller Common' is an open source Java library forked from Databene Commons by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.

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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * Licensed 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 com.rapiddweller.common.mutator;

import com.rapiddweller.common.Accessor;
import com.rapiddweller.common.ComparableComparator;
import com.rapiddweller.common.Mutator;
import com.rapiddweller.common.NullSafeComparator;
import com.rapiddweller.common.StringUtil;
import com.rapiddweller.common.UpdateFailedException;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.util.Comparator;

/**
 * Mutator that is only applied if a condition is true.
 * Created: 08.05.2005 06:47:17
 */
@SuppressWarnings("unchecked")
public class ConditionalMutator extends MutatorProxy {

  /**
   * The constant ASSERT_EQUALS.
   */
  public static final int ASSERT_EQUALS = 0;
  /**
   * The constant OVERWRITE.
   */
  public static final int OVERWRITE = 1;
  /**
   * The constant SET_IF_UNDEFINED.
   */
  public static final int SET_IF_UNDEFINED = 2;
  /**
   * The constant SET_IF_GREATER.
   */
  public static final int SET_IF_GREATER = 3;

  /**
   * The Mode.
   */
  protected int mode;

  @SuppressWarnings("rawtypes")
  private final Comparator comparator;

  @SuppressWarnings("rawtypes")
  private final Accessor accessor;

  private static final Logger logger = LogManager.getLogger(ConditionalMutator.class);

  /**
   * Instantiates a new Conditional mutator.
   *
   * @param realMutator the real mutator
   * @param accessor    the accessor
   * @param mode        the mode
   */
  @SuppressWarnings("rawtypes")
  public ConditionalMutator(Mutator realMutator, Accessor accessor, int mode) {
    super(realMutator);
    this.accessor = accessor;
    this.mode = mode;
    comparator = new ComparableComparator();
  }

  @Override
  public void setValue(Object target, Object value) throws UpdateFailedException {
    Object oldValue = accessor.getValue(target);
    switch (mode) {
      case OVERWRITE:
        realMutator.setValue(target, value);
        break;
      case ASSERT_EQUALS:
        if (isEmpty(oldValue)) {
          realMutator.setValue(target, value);
        } else if (!NullSafeComparator.equals(oldValue, value)) {
          throw new UpdateFailedException("Mutator " + realMutator + " expected '" + oldValue + "', "
              + "but found '" + value + "'");
        } else {
          logger.debug("no update needed by " + realMutator);
        }
        break;
      case SET_IF_UNDEFINED:
        if (isEmpty(oldValue)) {
          realMutator.setValue(target, value);
        } else {
          logger.debug("no update needed by " + realMutator);
        }
        break;
      case SET_IF_GREATER:
        if (isEmpty(oldValue)) {
          realMutator.setValue(target, value);
        } else if (comparator.compare(oldValue, value) == -1) {
          realMutator.setValue(target, value);
        } else {
          logger.debug("no update needed by " + realMutator);
        }
        break;
      default:
        throw new RuntimeException("Illegal mode");
    }

  }

  // private helpers -------------------------------------------------------------------------------------------------

  private static boolean isEmpty(Object value) {
    return (value instanceof String ? StringUtil.isEmpty((String) value) : value == null);
  }

}