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//
// Copyright 2010 EXANPE 
//
// 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 fr.exanpe.tapestry.tldgen.utils;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import org.codehaus.classworlds.ClassRealm;
import org.codehaus.plexus.component.configurator.AbstractComponentConfigurator;
import org.codehaus.plexus.component.configurator.ComponentConfigurationException;
import org.codehaus.plexus.component.configurator.ConfigurationListener;
import org.codehaus.plexus.component.configurator.converters.composite.ObjectWithFieldsConverter;
import org.codehaus.plexus.component.configurator.converters.special.ClassRealmConverter;
import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluationException;
import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluator;
import org.codehaus.plexus.configuration.PlexusConfiguration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A custom ComponentConfigurator which adds the project's runtime classpath elements
 * to the
 * 
 * @author Brian Jackson
 * @since Aug 1, 2008 3:04:17 PM
 * @plexus.component role="org.codehaus.plexus.component.configurator.ComponentConfigurator"
 *                   role-hint="include-project-dependencies"
 * @plexus.requirement
 *                     role="org.codehaus.plexus.component.configurator.converters.lookup.ConverterLookup"
 *                     role-hint="default"
 */
public class PlexusFullProjectClassLoader extends AbstractComponentConfigurator
{

    private static final Logger LOGGER = LoggerFactory.getLogger(PlexusFullProjectClassLoader.class);

    public void configureComponent(Object component, PlexusConfiguration configuration, ExpressionEvaluator expressionEvaluator, ClassRealm containerRealm,
            ConfigurationListener listener) throws ComponentConfigurationException
    {

        addProjectDependenciesToClassRealm(expressionEvaluator, containerRealm);

        converterLookup.registerConverter(new ClassRealmConverter(containerRealm));

        ObjectWithFieldsConverter converter = new ObjectWithFieldsConverter();

        converter.processConfiguration(converterLookup, component, containerRealm.getClassLoader(), configuration, expressionEvaluator, listener);
    }

    private void addProjectDependenciesToClassRealm(ExpressionEvaluator expressionEvaluator, ClassRealm containerRealm) throws ComponentConfigurationException
    {
        List runtimeClasspathElements;
        try
        {
            // noinspection unchecked
            runtimeClasspathElements = (List) expressionEvaluator.evaluate("${project.runtimeClasspathElements}");
        }
        catch (ExpressionEvaluationException e)
        {
            throw new ComponentConfigurationException("There was a problem evaluating: ${project.runtimeClasspathElements}", e);
        }

        // Add the project dependencies to the ClassRealm
        final URL[] urls = buildURLs(runtimeClasspathElements);
        for (URL url : urls)
        {
            containerRealm.addConstituent(url);
        }
    }

    private URL[] buildURLs(List runtimeClasspathElements) throws ComponentConfigurationException
    {
        // Add the projects classes and dependencies
        List urls = new ArrayList(runtimeClasspathElements.size());
        for (String element : runtimeClasspathElements)
        {
            try
            {
                final URL url = new File(element).toURI().toURL();
                urls.add(url);
                if (LOGGER.isDebugEnabled())
                {
                    LOGGER.debug("Added to project class loader: " + url);
                }
            }
            catch (MalformedURLException e)
            {
                throw new ComponentConfigurationException("Unable to access project dependency: " + element, e);
            }
        }

        // Add the plugin's dependencies (so Trove stuff works if Trove isn't on
        return urls.toArray(new URL[urls.size()]);
    }

}