/*
 * 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.core.loader;

import java.util.HashMap;
import java.util.Map;
import javax.xml.namespace.QName;
import static javax.xml.stream.XMLStreamConstants.END_ELEMENT;
import static javax.xml.stream.XMLStreamConstants.START_ELEMENT;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import static org.osoa.sca.Constants.SCA_NS;
import org.osoa.sca.annotations.Constructor;
import org.osoa.sca.annotations.Reference;

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.UnrecognizedElementException;
import org.apache.tuscany.spi.model.BindingDefinition;
import org.apache.tuscany.spi.model.ModelObject;
import org.apache.tuscany.spi.model.Multiplicity;
import org.apache.tuscany.spi.model.ReferenceDefinition;
import org.apache.tuscany.spi.model.ServiceContract;

/**
 * Loads a reference from an XML-based assembly file
 *
 * @version $Rev$ $Date$
 */
public class ReferenceLoader extends LoaderExtension<ReferenceDefinition> {
    public static final QName REFERENCE = new QName(SCA_NS, "reference");
    private static final Map<String, Multiplicity> MULTIPLICITY = new HashMap<String, Multiplicity>(4);

    static {
        MULTIPLICITY.put("0..1", Multiplicity.ZERO_ONE);
        MULTIPLICITY.put("1..1", Multiplicity.ONE_ONE);
        MULTIPLICITY.put("0..n", Multiplicity.ZERO_N);
        MULTIPLICITY.put("1..n", Multiplicity.ONE_N);
    }

    @Constructor
    public ReferenceLoader(@Reference LoaderRegistry registry) {
        super(registry);
    }

    public QName getXMLType() {
        return REFERENCE;
    }

    public ReferenceDefinition load(ModelObject object, XMLStreamReader reader, DeploymentContext context)
        throws XMLStreamException, LoaderException {
        assert REFERENCE.equals(reader.getName());
        String name = reader.getAttributeValue(null, "name");
        String multiplicityVal = reader.getAttributeValue(null, "multiplicity");
        Multiplicity multiplicity = multiplicity(multiplicityVal, Multiplicity.ONE_ONE);
        ReferenceDefinition referenceDefinition = new ReferenceDefinition();
        referenceDefinition.setMultiplicity(multiplicity);
        referenceDefinition.setUri(context.getComponentId().resolve('#' + name));
        while (true) {
            switch (reader.next()) {
                case START_ELEMENT:
                    ModelObject o = registry.load(null, reader, context);
                    if (o instanceof ServiceContract) {
                        referenceDefinition.setServiceContract((ServiceContract) o);
                    } else if (o instanceof BindingDefinition) {
                        referenceDefinition.addBinding((BindingDefinition) o);
                    } else {
                        throw new UnrecognizedElementException(reader.getName());
                    }
                    break;
                case END_ELEMENT:
                    return referenceDefinition;
            }
        }
    }

    /**
     * Convert a "multiplicity" attribute to the equivalent enum value.
     *
     * @param multiplicity the attribute to convert
     * @param def          the default value
     * @return the enum equivalent
     */
    private static Multiplicity multiplicity(String multiplicity, Multiplicity def) {
        return multiplicity == null ? def : MULTIPLICITY.get(multiplicity);
    }

}