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package org.fabric3.contribution.processor;

import javax.xml.namespace.QName;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import org.fabric3.api.host.Fabric3Exception;
import org.fabric3.api.host.contribution.Deployable;
import org.fabric3.api.model.type.component.Composite;
import org.fabric3.api.model.type.component.Property;
import org.fabric3.spi.contribution.Contribution;
import org.fabric3.spi.contribution.ContributionManifest;
import org.fabric3.spi.contribution.Resource;
import org.fabric3.spi.contribution.ResourceElement;
import org.fabric3.spi.contribution.ResourceState;
import org.fabric3.spi.contribution.manifest.QNameExport;
import org.fabric3.spi.contribution.manifest.QNameSymbol;
import org.fabric3.spi.contribution.xml.XmlProcessor;
import org.fabric3.spi.contribution.xml.XmlProcessorRegistry;
import org.fabric3.spi.introspection.IntrospectionContext;
import org.fabric3.spi.introspection.xml.LoaderHelper;
import org.oasisopen.sca.annotation.Destroy;
import org.oasisopen.sca.annotation.EagerInit;
import org.oasisopen.sca.annotation.Init;
import org.oasisopen.sca.annotation.Reference;
import org.w3c.dom.Document;

/**
 * Processes XML config contributions. Config XML contributions are used to deploy properties to the domain that may be referenced by components in other
 * contributions. This provides an accessible mechanism for deploying configuration separate from application code archives.  Config files must use the
 * config element as the document root. The config element has two attributes, name and targetNamespace. As show in the following
 * example, name identifies the property name and targetNamespaces identifies the namespace the config contribution exports:
 *  * <config xmlns="urn:fabric3.org"
 *       name="MyProperty"
 *       targetNamespace="urn:foo.com">
 *
 *   <foo xmlns="urn:foo.com">
 *       <bar/>
 *   </foo>
 * </config>
 * 
 *  The exported namespace can be imported by another contribution that depends on the property to guarantee the runtime performs contribution ordering.
 *  The implementation works by parsing the contents of the config file into a property which is added to a synthetic deployable composite. When the
 * composite is deployed, the property will be added to the domain where it can be referenced.
 */
@EagerInit
public class ConfigProcessor implements XmlProcessor {
    private static final QName TYPE = new QName(org.fabric3.api.Namespaces.F3, "config");
    private LoaderHelper loaderHelper;
    private XmlProcessorRegistry processorRegistry;

    public ConfigProcessor(@Reference XmlProcessorRegistry processorRegistry, @Reference LoaderHelper loaderHelper) {
        this.processorRegistry = processorRegistry;
        this.loaderHelper = loaderHelper;
    }

    @Init
    public void init() {
        processorRegistry.register(this);
    }

    @Destroy
    public void destroy() {
        processorRegistry.unregister(TYPE);
    }

    public QName getType() {
        return TYPE;
    }

    public void processContent(Contribution contribution, XMLStreamReader reader, IntrospectionContext context) {
        try {
            String localName = reader.getAttributeValue(null, "name");
            String targetNamespace = reader.getAttributeValue(null, "targetNamespace");

            Document value = loaderHelper.loadPropertyValues(reader);

            QName name = new QName(targetNamespace, "F3Synthetic" + localName);

            Property property = new Property(localName);
            property.setDefaultValue(value);
            Composite composite = new Composite(name);

            composite.add(property);

            Resource resource = new Resource(contribution, null, "application/xml");
            QNameSymbol symbol = new QNameSymbol(name);
            ResourceElement element = new ResourceElement<>(symbol);
            element.setValue(composite);
            resource.addResourceElement(element);
            resource.setState(ResourceState.PROCESSED);

            contribution.addResource(resource);

            ContributionManifest manifest = contribution.getManifest();

            Deployable deployable = new Deployable(name);
            manifest.addDeployable(deployable);

            QNameExport export = new QNameExport(targetNamespace);
            manifest.addExport(export);
        } catch (XMLStreamException e) {
            throw new Fabric3Exception(e);
        }
    }

}