/**
 * 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 org.apache.camel.CamelContext;
import org.apache.camel.NoSuchLanguageException;
import org.apache.camel.spi.Language;
import org.apache.camel.spi.LanguageResolver;
import org.apache.camel.util.ObjectHelper;
import org.osgi.framework.BundleContext;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class OsgiLanguageResolver implements LanguageResolver {
    private static final transient Logger LOG = LoggerFactory.getLogger(OsgiLanguageResolver.class);

    private final BundleContext bundleContext;

    public OsgiLanguageResolver(BundleContext bundleContext) {
        this.bundleContext = bundleContext;
    }

    public Language resolveLanguage(String name, CamelContext context) {
        // lookup in registry first
        Object bean = null;
        try {
            bean = context.getRegistry().lookup(name);
            if (bean != null && LOG.isDebugEnabled()) {
                LOG.debug("Found language: " + name + " in registry: " + bean);
            }
        } catch (Exception e) {
            if (LOG.isDebugEnabled()) {
                LOG.debug("Ignored error looking up bean: " + name + ". Error: " + e);
            }
        }
        if (bean instanceof Language) {
            return (Language)bean;
        }
        Language lang = getLanguage(name, context);
        if (lang != null) {
            return lang;
        }
        LanguageResolver resolver = getLanguageResolver("default", context);
        if (resolver != null) {
            return resolver.resolveLanguage(name, context);
        }
        throw new NoSuchLanguageException(name);
    }

    protected Language getLanguage(String name, CamelContext context) {
        if (LOG.isTraceEnabled()) {
            LOG.trace("Finding Language: " + name);
        }
        try {
            ServiceReference[] refs = bundleContext.getServiceReferences(LanguageResolver.class.getName(), "(language=" + name + ")");
            if (refs != null && refs.length > 0) {
                LanguageResolver resolver = (LanguageResolver) bundleContext.getService(refs[0]);
                return resolver.resolveLanguage(name, context);
            }
            return null;
        } catch (InvalidSyntaxException e) {
            throw ObjectHelper.wrapRuntimeCamelException(e);
        }
    }

    protected LanguageResolver getLanguageResolver(String name, CamelContext context) {
        if (LOG.isTraceEnabled()) {
            LOG.trace("Finding LanguageResolver: " + name);
        }
        try {
            ServiceReference[] refs = bundleContext.getServiceReferences(LanguageResolver.class.getName(), "(resolver=" + name + ")");
            if (refs != null && refs.length > 0) {
                LanguageResolver resolver = (LanguageResolver) bundleContext.getService(refs[0]);
                return resolver;
            }
            return null;
        } catch (InvalidSyntaxException e) {
            throw ObjectHelper.wrapRuntimeCamelException(e);
        }
    }

}
