/**
 * The contents of this file are subject to the license and copyright
 * detailed in the LICENSE and NOTICE files at the root of the source
 * tree and available online at
 *
 * http://www.dspace.org/license/
 */
package org.dspace.app.rest.model.hateoas;

import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import org.dspace.app.rest.model.RestModel;
import org.dspace.app.rest.utils.Utils;
import org.springframework.hateoas.Link;
import org.springframework.hateoas.ResourceSupport;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.annotation.JsonUnwrapped;

/**
 * A base class for DSpace Rest HAL Resource. The HAL Resource wraps the REST
 * Resource adding support for the links and embedded resources. Each property
 * of the wrapped REST resource is automatically translated in a link and the
 * available information included as embedded resource
 * 
 * @author Andrea Bollini (andrea.bollini at 4science.it)
 *
 */
public abstract class DSpaceResource<T extends RestModel> extends ResourceSupport {
	@JsonUnwrapped
	private final T data;

	@JsonProperty(value = "_embedded")
	@JsonInclude(Include.NON_EMPTY)
	private Map<String, Object> embedded = new HashMap<String, Object>();

	public DSpaceResource(T data, Utils utils, String... rels) {
		this.data = data;

		if (data != null) {
			try {
				for (PropertyDescriptor pd : Introspector.getBeanInfo(data.getClass()).getPropertyDescriptors()) {
					Method readMethod = pd.getReadMethod();
					if (readMethod != null && !"class".equals(pd.getName())) {
						if (RestModel.class.isAssignableFrom(readMethod.getReturnType())) {
							this.add(utils.linkToSubResource(data, pd.getName()));
							RestModel linkedObject = (RestModel) readMethod.invoke(data);
							if (linkedObject != null) {
								embedded.put(pd.getName(),
										utils.getResourceRepository(linkedObject.getType()).wrapResource(linkedObject));
							} else {
								embedded.put(pd.getName(), null);
							}
	
							Method writeMethod = pd.getWriteMethod();
							writeMethod.invoke(data, new Object[] { null });
						}
					}
				}
			} catch (IntrospectionException | IllegalArgumentException | IllegalAccessException
					| InvocationTargetException e) {
				throw new RuntimeException(e.getMessage(), e);
			}
			this.add(utils.linkToSingleResource(data, Link.REL_SELF));
		}
	}

	public Map<String, Object> getEmbedded() {
		return embedded;
	}

	public T getData() {
		return data;
	}
}