SimpleTagProposalManager.java

/**
 * <a href="http://www.openolat.org">
 * OpenOLAT - Online Learning and Training</a><br>
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License"); <br>
 * you may not use this file except in compliance with the License.<br>
 * You may obtain a copy of the License at the
 * <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache homepage</a>
 * <p>
 * Unless required by applicable law or agreed to in writing,<br>
 * software distributed under the License is distributed on an "AS IS" BASIS, <br>
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. <br>
 * See the License for the specific language governing permissions and <br>
 * limitations under the License.
 * <p>
 * Initial code contributed and copyrighted by<br>
 * frentix GmbH, http://www.frentix.com
 * <p>
 */

package org.olat.core.commons.services.tagging.manager;

import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

import org.olat.core.commons.persistence.DB;
import org.olat.core.commons.persistence.DBQuery;
import org.olat.core.commons.services.tagging.model.TagImpl;
import org.olat.core.manager.BasicManager;
import org.olat.core.util.StringHelper;

/**
 * 
 * Description:<br>
 * A very simple manager to propose tags.
 * 
 * <P>
 * Initial Date:  19 jul. 2010 <br>
 * @author srosse, stephane.rosse@frentix.com, http://www.frentix.com
 */
public class SimpleTagProposalManager extends BasicManager implements TagProposalManager {

	private DB dbInstance;
	
	public SimpleTagProposalManager() {
		//
	}
	
	
	/**
	 * [used by Spring]
	 * @param dbInstance
	 */
	public void setDbInstance(DB dbInstance) {
		this.dbInstance = dbInstance;
	}

	@Override
	public List<String> proposeTagsForInputText(String referenceText, boolean onlyExisting) {
		List<String> tokens = new ArrayList<String>();
		StringTokenizer tokenizer = new StringTokenizer(referenceText, " \t\n\r\f.,;:-!?");
		for (; tokenizer.hasMoreTokens();) {
			String next = tokenizer.nextToken().trim();
			next = next.replace(" ", "");
			if (!tokens.contains(next) && StringHelper.containsNonWhitespace(next) && next.length() > 3) tokens.add(next);
			if (tokens.size() == 500) {
				break;
			}
		}

		if (onlyExisting) {
			StringBuilder sb = new StringBuilder();
			sb.append("select tag.tag from ").append(TagImpl.class.getName()).append(" tag where tag.tag in (:tokens) group by tag.tag");
			DBQuery query = dbInstance.createQuery(sb.toString());
			query.setParameterList("tokens", tokens);

			@SuppressWarnings("unchecked")
			List<String> currentTags = query.list();
			return currentTags;
		} else {
			return tokens;
		}
	}
}