/*
 * Copyright  2003-2004 The Apache Software Foundation.
 *
 *  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.
 *
 */

/*
 * This class was taken nearly verbatim from http://junit.sourceforge.net/doc/faq/faq.htm#tests_11 
 * I did add the setValue(Object, String, Object)
 * Jason Essington <mailto:jasone@greenrivercomputing.com>
 */
package wssec;
import java.lang.reflect.*;

/**
 * a.k.a. The "ObjectMolester"
 * <p>
 * This class is used to access a method or field of an object no
 * matter what the access modifier of the method or field.  The syntax
 * for accessing fields and methods is out of the ordinary because this
 * class uses reflection to peel away protection.
 * <p>
 * Here is an example of using this to access a private member.
 * <code>resolveName</code> is a private method of <code>Class</code>.
 *
 * <pre>
 * Class c = Class.class;
 * System.out.println(
 *      PrivilegedAccessor.invokeMethod( c,
 *                                       "resolveName",
 *                                       "/net/iss/common/PrivilegeAccessor" ) );
 * </pre>
 *
 * @author Charlie Hubbard (chubbard@iss.net)
 * @author Prashant Dhokte (pdhokte@iss.net)
 */

public class PrivilegedAccessor {

    /**
     * Gets the value of the named field and returns it as an object.
     *
     * @param instance the object instance
     * @param fieldName the name of the field
     * @return an object representing the value of the field
     */
    public static Object getValue( Object instance, String fieldName ) 
          throws IllegalAccessException, NoSuchFieldException {
        Field field = getField(instance.getClass(), fieldName);
        field.setAccessible(true);
        return field.get(instance);
    }
    
    /**
     * Sets the value of the given field on the object instance supplied to the value supplied.
     * @param instance the object instance
     * @param fieldName the name of the field
     * @param value the value to assign to the field
     * @throws IllegalAccessException
     * @throws NoSuchFieldException
     */
    public static void setValue( Object instance, String fieldName, Object value ) 
          throws IllegalAccessException, NoSuchFieldException {
       Field field = getField(instance.getClass(), fieldName);
       field.setAccessible(true);
       field.set(instance, value);
    }
    
    /**
     * Calls a method on the given object instance with the given argument.
     *
     * @param instance the object instance
     * @param methodName the name of the method to invoke
     * @param arg the argument to pass to the method
     * @see PrivilegedAccessor#invokeMethod(Object,String,Object[])
     */
    public static Object invokeMethod( Object instance, String methodName, Object arg ) throws NoSuchMethodException,
                                                         IllegalAccessException, InvocationTargetException  {
        Object[] args = new Object[1];
        args[0] = arg;
        return invokeMethod(instance, methodName, args);
    }

    /**
     * Calls a method on the given object instance with the given arguments.
     *
     * @param instance the object instance
     * @param methodName the name of the method to invoke
     * @param args an array of objects to pass as arguments
     * @see PrivilegedAccessor#invokeMethod(Object,String,Object)
     */
    public static Object invokeMethod( Object instance, String methodName, Object[] args ) throws NoSuchMethodException,
                                                             IllegalAccessException, InvocationTargetException  {
        Class[] classTypes = null;
        if( args != null) {
            classTypes = new Class[args.length];
            for( int i = 0; i < args.length; i++ ) {
                if( args[i] != null )
                    classTypes[i] = args[i].getClass();
            }
        }
        return getMethod(instance,methodName,classTypes).invoke(instance,args);
    }

    /**
     *
     * @param instance the object instance
     * @param methodName the
     */
    public static Method getMethod( Object instance, String methodName, Class[] classTypes ) throws NoSuchMethodException {
        Method accessMethod = getMethod(instance.getClass(), methodName, classTypes);
        accessMethod.setAccessible(true);
        return accessMethod;
    }

    /**
     * Return the named field from the given class.
     */
    private static Field getField(Class thisClass, String fieldName) throws NoSuchFieldException {
        if (thisClass == null)
            throw new NoSuchFieldException("Invalid field : " + fieldName);
        try {
            return thisClass.getDeclaredField( fieldName );
        }
        catch(NoSuchFieldException e) {
            return getField(thisClass.getSuperclass(), fieldName);
        }
    }

    /**
     * Return the named method with a method signature matching classTypes
     * from the given class.
     */
    private static Method getMethod(Class thisClass, String methodName, Class[] classTypes) throws NoSuchMethodException {
        if (thisClass == null)
            throw new NoSuchMethodException("Invalid method : " + methodName);
        try {
            return thisClass.getDeclaredMethod( methodName, classTypes );
        }
        catch(NoSuchMethodException e) {
            return getMethod(thisClass.getSuperclass(), methodName, classTypes);
        }
    }
}