/*
    * Licensed under the GPL License. You may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *   https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
    *
    * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
    * WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
    * PURPOSE.
   */
  package psiprobe.tools;
  
  import java.lang.reflect.Field;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * The Class SimpleAccessor.
   */
  public class SimpleAccessor implements Accessor {
  
    /** The Constant logger. */
    private static final Logger logger = LoggerFactory.getLogger(SimpleAccessor.class);
  
    @Override
    public Object get(Object obj, Field field) {
      boolean accessible = pre(obj, field);
      try {
        return get0(obj, field);
      } catch (IllegalArgumentException | IllegalAccessException e) {
        logger.trace("", e);
        return null;
      } finally {
        post(field, accessible);
      }
    }
  
    /**
     * Gets the 0.
     *
     * @param obj the obj
     * @param field the field
     *
     * @return the 0
     *
     * @throws IllegalAccessException the illegal access exception
     */
    private Object get0(Object obj, Field field) throws IllegalAccessException {
  
      if (field.canAccess(obj)) {
        return field.get(obj);
      }
      return null;
    }
  
    /**
     * Pre.
     *
     * @param obj the obj
     * @param field the field
     *
     * @return true, if successful
     */
    private boolean pre(Object obj, Field field) {
      boolean accessible = field.canAccess(obj);
      if (!accessible) {
        try {
          field.setAccessible(true);
        } catch (SecurityException ex) {
          logger.trace("", ex);
        }
      }
      return accessible;
    }
  
    /**
     * Post.
     *
     * @param field the field
     * @param value the value
     */
    private void post(Field field, boolean value) {
      if (!value) {
        try {
          field.setAccessible(false);
        } catch (SecurityException ex) {
          logger.trace("", ex);
        }
      }
    }
  
  }