MetadataUIPFilter.java

/**
 * Copyright 2008 The University of North Carolina at Chapel Hill
 *
 * Licensed 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 edu.unc.lib.dl.update;

import java.util.List;

import org.apache.log4j.Logger;
import org.jdom2.Element;

public abstract class MetadataUIPFilter implements UIPUpdateFilter {
	private static Logger log = Logger.getLogger(MetadataUIPFilter.class);
	
	protected Element getNewModifiedElement(MetadataUIP uip, String datastreamName) {
		Element incoming = uip.getIncomingData().get(datastreamName);
		return getNewModifiedElement(uip, datastreamName, incoming);
	}

	protected Element getNewModifiedElement(MetadataUIP uip, String datastreamName, Element incoming) {
		log.debug("Getting new modified element using base " + datastreamName + " and " + incoming);
		if (incoming == null)
			return null;
		// If this is a replace operation, then the new modified element is simply the incoming element.
		if (uip.getOperation().equals(UpdateOperation.REPLACE))
			return (Element) incoming.clone();

		return this.getBaseElement(uip, datastreamName, incoming);
	}

	protected Element getBaseElement(MetadataUIP uip, String datastreamName, Element incoming) {
		Element modified = uip.getModifiedData().get(datastreamName);
		Element original = uip.getOriginalData().get(datastreamName);

		Element newModified = null;

		if (modified == null) {
			// If there is no original or modified data, than return the incoming as new modified
			if (original == null) {
				return (Element) incoming.clone();
			} else {
				// Set the base for the new modified object to the original data
				newModified = (Element) original.clone();
			}
		} else {
			// Use the previous modified data
			newModified = (Element) modified.clone();
		}

		return newModified;
	}

	/**
	 * Performs an add operation assuming there are no uniqueness restrictions
	 * 
	 * @param uip
	 * @return
	 * @throws UIPException
	 */
	protected Element performAdd(MetadataUIP uip, String datastreamName) throws UIPException {
		Element incoming = uip.getIncomingData().get(datastreamName);
		return performAdd(uip, datastreamName, incoming);
	}

	protected Element performAdd(MetadataUIP uip, String datastreamName, Element incoming) throws UIPException {
		Element newModified = getNewModifiedElement(uip, datastreamName, incoming);
		if (newModified == null)
			return null;

		// Clone all the child elements of the incoming metadata
		List<Element> incomingElements = (List<Element>) incoming.getChildren();
		// Add all the incoming element children to the base modified object
		for (Element incomingElement : incomingElements) {
			newModified.addContent((Element) incomingElement.clone());
		}

		return newModified;
	}

	protected Element performReplace(MetadataUIP uip, String datastreamName) throws UIPException {
		return getNewModifiedElement(uip, datastreamName);
	}

	protected Element performReplace(MetadataUIP uip, String baseDatastream, String incomingDatastream)
			throws UIPException {
		return getNewModifiedElement(uip, baseDatastream, uip.getIncomingData().get(incomingDatastream));
	}

	protected Element performReplace(MetadataUIP uip, String datastreamName, Element incoming) throws UIPException {
		return getNewModifiedElement(uip, datastreamName, incoming);
	}
}