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package com.devonfw.cobigen.api.util;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import com.devonfw.cobigen.api.exception.CobiGenRuntimeException;

/**
 * This class provides commonly interesting exception handling methods
 *
 * @author Malte Brunnlieb
 * @version $Revision$
 */
public class ExceptionUtil {

  /**
   * Tries to find the exception with the given type in the causing stack trace of exceptions of the given exception
   * e
   *
   * @param  type of the throwable to be found in the exception's stack trace
   *
   * @param e super exception to retrieve the causes stack from
   * @param cause {@link Class} which should be found and retrieved
   * @return the cause with the given type if found

   *         otherwise null
   */
  @SuppressWarnings("unchecked")
  public static  T getCause(Throwable e, Class cause) {

    Throwable curr = e;
    while (curr != null && !cause.isAssignableFrom(curr.getClass())) {
      curr = curr.getCause();
    }
    if (curr != null) {
      return (T) curr;
    } else {
      return null;
    }
  }

  /**
   * Tries to find the exception with the given type in the causing stack trace of exceptions of the given exception
   * e
   *
   * @param e super exception to retrieve the causes stack from
   * @param causes {@link Class}es which should be found and retrieved in sorted with a decreasing priority to be found.
   * @return the cause with the given type if found

   *         otherwise null
   */
  public static Throwable getCause(Throwable e, Class... causes) {

    for (Class cause : causes) {
      Throwable curr = e;
      while (curr != null && !cause.isAssignableFrom(curr.getClass())) {
        curr = curr.getCause();
      }
      if (curr != null) {
        // if found return as this exception has a higher priority as the upcoming
        return curr;
      }
    }
    return null;
  }

  /**
   * Invoking the target method while assuring proper exception handling.
   *
   * @param targetObject target object to invoke the method on
   * @param method to be called.
   * @param args parameters to be passed.
   * @return the resulting object.
   */
  public static Object invokeTarget(Object targetObject, Method method, Object[] args) {

    try {
      return method.invoke(targetObject, args);
    } catch (IllegalAccessException e) {
      throw new CobiGenRuntimeException("Could not access method " + method.toGenericString() + ". This is a bug!", e);
    } catch (InvocationTargetException e) {
      CobiGenRuntimeException cause = ExceptionUtil.getCause(e, CobiGenRuntimeException.class);
      if (cause != null) {
        throw cause;
      } else {
        throw new CobiGenRuntimeException("Unable to invoke " + method.toGenericString() + ".", e);
      }
    }
  }
}