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/**
 * Copyright (C) 2010 Mathieu Carbou 
 *
 * 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.mycila.ujd.impl;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.mycila.ujd.api.Container;
import com.mycila.ujd.api.JavaClass;
import com.mycila.ujd.api.Loader;
import com.mycila.ujd.api.UJD;

import java.net.URL;
import java.net.URLClassLoader;
import java.util.Arrays;
import java.util.Collections;

import static com.google.common.collect.Iterables.*;

/**
 * @author Mathieu Carbou ([email protected])
 */
final class LoaderImpl implements Loader {

    private final ClassLoader classLoader;
    private final DefaultJVM jvm;

    LoaderImpl(DefaultJVM jvm, ClassLoader classLoader) {
        if (jvm == null || classLoader == null)
            throw new IllegalArgumentException("args cannot be null");
        this.jvm = jvm;
        this.classLoader = classLoader;
    }

    public Iterable getChilds() {
        return filter(jvm.getLoaders(), UJD.hasParentLoader(LoaderImpl.this));
    }

    public String getName() {
        return classLoader.getClass().getName() + "@" + Integer.toHexString(classLoader.hashCode());
    }

    public Loader getParent() {
        return jvm.loaderRegistry.get(get().getParent());
    }

    public Iterable getContainers() {
        final String javaHome = System.getProperty("java.home");
        if (classLoader instanceof URLClassLoader) {
            final Iterable urls;
            try {
                // when tomcat/jboss unload the webapp classloader (hot deploy)
                // the classloader with some classes may stay there (in case of
                // programming errors from webapp auhtors). Calling getURLs() on
                // such a classloader fails
                urls = Arrays.asList(((URLClassLoader) classLoader).getURLs());
            } catch (RuntimeException e) {
                return Collections.emptyList();
            }
            return transform(
                    filter(urls, new Predicate() {
                        public boolean apply(URL url) {
                            // skip JVM classpath
                            return !url.toExternalForm().contains(javaHome);
                        }
                    }),
                    new Function() {
                        public Container apply(URL from) {
                            // transform URL into container, caching it if needed
                            return jvm.containerRegistry.get(from);
                        }
                    });
        }
        return Collections.emptyList();
    }

    public Iterable> getClasses() {
        return filter(jvm.getClasses(), UJD.hasLoader(LoaderImpl.this));
    }

    public ClassLoader get() {
        return classLoader;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        LoaderImpl loader = (LoaderImpl) o;
        return classLoader.equals(loader.classLoader);
    }

    @Override
    public int hashCode() {
        return classLoader.hashCode();
    }

    @Override
    public String toString() {
        return getName();
    }
}