/*
 * 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.tuscany.container.script;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import static org.osoa.sca.Version.XML_NAMESPACE_1_0;
import org.osoa.sca.annotations.Constructor;

import org.apache.tuscany.spi.annotation.Autowire;
import org.apache.tuscany.spi.component.CompositeComponent;
import org.apache.tuscany.spi.deployer.DeploymentContext;
import org.apache.tuscany.spi.extension.LoaderExtension;
import org.apache.tuscany.spi.loader.LoaderException;
import org.apache.tuscany.spi.loader.LoaderRegistry;
import org.apache.tuscany.spi.loader.LoaderUtil;
import org.apache.tuscany.spi.loader.MissingResourceException;
import org.apache.tuscany.spi.model.ModelObject;

/**
 * Loader for handling implementation.script elements.
 * <p/>
 * <implementation.script script="path/foo.py" class="myclass">
 *
 * @version $Rev$ $Date$
 */
public class ScriptImplementationLoader extends LoaderExtension<ScriptImplementation> {

    private static final QName IMPLEMENTATION_SCRIPT = new QName(XML_NAMESPACE_1_0, "implementation.script");

    @Constructor({"registry"})
    public ScriptImplementationLoader(@Autowire LoaderRegistry registry) {
        super(registry);
    }

    public QName getXMLType() {
        return IMPLEMENTATION_SCRIPT;
    }

    public ScriptImplementation load(CompositeComponent parent, ModelObject mo, XMLStreamReader reader,
                                     DeploymentContext deploymentContext) throws XMLStreamException, LoaderException {
        String scriptName = reader.getAttributeValue(null, "script");
        if (scriptName == null) {
            throw new MissingResourceException("implementation element has no 'script' attribute");
        }

        String className = reader.getAttributeValue(null, "class");

        LoaderUtil.skipToEndElement(reader);

        ClassLoader cl = deploymentContext.getClassLoader();
        String scriptSource = loadSource(cl, scriptName);

//        ScriptInstanceFactory instanceFactory = new ScriptInstanceFactory(scriptName, className, scriptSource, cl);

        ScriptImplementation implementation = new ScriptImplementation();
        implementation.setResourceName(scriptName);
        implementation.setScriptSource(scriptSource);
        implementation.setClassName(className);
        implementation.setScriptName(scriptName);
        implementation.setClassLoader(cl);
        //implementation.setScriptInstanceFactory(instanceFactory);

        registry.loadComponentType(parent, implementation, deploymentContext);

        return implementation;
    }

    protected String loadSource(ClassLoader cl, String resource) throws LoaderException {
        URL url = cl.getResource(resource);
        if (url == null) {
            throw new MissingResourceException(resource);
        }
        InputStream is;
        try {
            is = url.openStream();
        } catch (IOException e) {
            throw new MissingResourceException(resource, e);
        }
        try {
            Reader reader = new InputStreamReader(is, "UTF-8");
            char[] buffer = new char[1024];
            StringBuilder source = new StringBuilder();
            int count;
            while ((count = reader.read(buffer)) > 0) {
                source.append(buffer, 0, count);
            }
            return source.toString();
        } catch (IOException e) {
            throw new LoaderException(resource, e);
        } finally {
            try {
                is.close();
            } catch (IOException e) {
                // ignore
            }
        }
    }
}