FormConverter

package net.peierls.util.restlet;

import java.io.IOException;
import java.io.Serializable;
import java.util.List;
import static java.util.Collections.singletonList;

import javax.inject.Inject;

import org.restlet.data.Form;
import org.restlet.data.MediaType;
import org.restlet.engine.converter.ConverterHelper;
import org.restlet.engine.resource.VariantInfo;
import org.restlet.representation.Representation;
import org.restlet.representation.Variant;
import org.restlet.resource.Resource;


/**
 * Converts form representations to Java POJOs that have been
 * marked with the {@link FormDeserializable} annotation,
 * using a {@link FormDeserializer}.
 * Only handles one direction, form to object.
 */
public class FormConverter extends ConverterHelper {

    @Inject FormConverter(FormDeserializer formDeserializer) {
        this.formDeserializer = formDeserializer;
    }

    @Override public List<VariantInfo> getVariants(Class<?> source) {
        if (source.isAnnotationPresent(FormDeserializable.class)) {
            return singletonList(VARIANT_FORM);
        } else {
            return null;
        }
    }

    @Override public <T> float score(Representation source, Class<T> target, Resource resource) {
        MediaType mediaType = source.getMediaType();
        if (target.isAnnotationPresent(FormDeserializable.class)
                && MediaType.APPLICATION_WWW_FORM.isCompatible(mediaType)) {
            return 2.0f;
        } else {
            return -1.0f;
        }
    }

    @SuppressWarnings("unchecked")
    @Override public <T> T toObject(Representation source,
            Class<T> target, Resource resource) throws IOException {

        if (target.isAnnotationPresent(FormDeserializable.class)) {
            Form form = new Form(source);
            return formDeserializer.deserialize(form, target);
        } else {
            return null;
        }
    }

    //
    // Don't need these because we're only going in one direction,
    // HTML form representation to Object.
    //

    @Override public List<Class<?>> getObjectClasses(Variant source) {
        return null;
    }

    @Override public float score(Object source, Variant target, Resource resource) {
        return -1.0f;
    }

    @Override public Representation toRepresentation(Object source,
            Variant target, Resource resource) throws IOException {

        return null;
    }


    private final FormDeserializer formDeserializer;


    private static final VariantInfo VARIANT_FORM = new VariantInfo(MediaType.APPLICATION_WWW_FORM);
}