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/**
 * Copyright (C) 2008 Ovea 
 *
 * 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 org.testatoo.selenium.server.util;

import java.util.ArrayList;
import java.util.List;

import static java.lang.Thread.currentThread;

/**
 * Thanks to jMock guys for this ClassLoader.
 */
public class SearchingClassLoader extends ClassLoader {

    private final ClassLoader nextToSearch;

    public SearchingClassLoader(ClassLoader parent, ClassLoader nextToSearch) {
        super(parent);
        this.nextToSearch = nextToSearch;
    }

    public static ClassLoader combineLoadersOf(Class... classes) {
        return combineLoadersOf(classes[0], classes);
    }

    private static ClassLoader combineLoadersOf(Class first, Class... others) {
        List loaders = new ArrayList();

        addIfNewElement(loaders, first.getClassLoader());
        for (Class c : others) {
            addIfNewElement(loaders, c.getClassLoader());
        }

        // To support Eclipse Plug-in tests.
        // In an Eclipse plug-in, jMock itself will not be on the system class loader
        // but in the class loader of the plug-in.
        //
        // Note: I've been unable to reproduce the error in jMock's test suite.
        addIfNewElement(loaders, SearchingClassLoader.class.getClassLoader());

        // To support the Maven Surefire plugin.
        // Note: I've been unable to reproduce the error in jMock's test suite.
        addIfNewElement(loaders, currentThread().getContextClassLoader());

        //Had to comment that out because it didn't work with in-container Spring tests
        //addIfNewElement(loaders, ClassLoader.getSystemClassLoader());

        return combine(loaders);
    }

    private static ClassLoader combine(List parentLoaders) {
        ClassLoader loader = parentLoaders.get(parentLoaders.size() - 1);

        for (int i = parentLoaders.size() - 2; i >= 0; i--) {
            loader = new SearchingClassLoader(parentLoaders.get(i), loader);
        }

        return loader;
    }

    private static void addIfNewElement(List loaders, ClassLoader c) {
        if (c != null && !loaders.contains(c)) {
            loaders.add(c);
        }
    }

    @Override
    protected Class findClass(String name) throws ClassNotFoundException {
        if (nextToSearch != null) {
            return nextToSearch.loadClass(name);
        } else {
            return super.findClass(name); // will throw ClassNotFoundException
        }
    }
}