/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.camel.core.osgi;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

import org.apache.camel.impl.DefaultClassResolver;
import org.apache.camel.util.CastUtils;
import org.apache.camel.util.ObjectHelper;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/* Using the bundle of CamelContext to load the class */
public class OsgiClassResolver extends DefaultClassResolver {
    private static final transient Logger LOG = LoggerFactory.getLogger(OsgiClassResolver.class);

    public BundleContext bundleContext;
    
    public OsgiClassResolver(BundleContext context) {
        this.bundleContext = context;
    }
    
    public Class<?> resolveClass(String name) {
        LOG.trace("Resolve class {}", name);
        name = ObjectHelper.normalizeClassName(name);
        Class<?> clazz = ObjectHelper.loadSimpleType(name);
        if (clazz == null) {
            clazz = doLoadClass(name, bundleContext.getBundle());
            LOG.trace("Loading class {} using BundleContext {} -> {}", new Object[]{name, bundleContext.getBundle(), clazz});
        }
        return clazz;
    }

    public <T> Class<T> resolveClass(String name, Class<T> type) {
        return CastUtils.cast(resolveClass(name));
    }

    public InputStream loadResourceAsStream(String uri) {
        ObjectHelper.notEmpty(uri, "uri");
        URL url = loadResourceAsURL(uri);
        InputStream answer = null;
        if (url != null) {
            try {
                answer = url.openStream();
            } catch (IOException ex) {
                throw new RuntimeException("Cannot load resource: " + uri, ex);
            }
        } 
        return answer;
    }

    public URL loadResourceAsURL(String uri) {
        ObjectHelper.notEmpty(uri, "uri");
        return bundleContext.getBundle().getResource(uri);
    }

    protected Class<?> doLoadClass(String name, Bundle loader) {
        ObjectHelper.notEmpty(name, "name");
        Class<?> answer = null;
        // Try to use the camel context's bundle's classloader to load the class
        if (loader != null) {
            try {
                answer = loader.loadClass(name);
            } catch (ClassNotFoundException e) {
                if (LOG.isTraceEnabled()) {
                    LOG.trace("Cannot load class: " + name + " using classloader: " + loader + ". This exception will be ignored.", e);
                }
            }
        }
        return answer;
    }
    
}
