DecoratedTaggingProvider.java

/**********************************************************************************
 * $URL: https://source.sakaiproject.org/svn/assignment/trunk/assignment-tool/tool/src/java/org/sakaiproject/assignment/taggable/tool/DecoratedTaggingProvider.java $
 * $Id: DecoratedTaggingProvider.java 105078 2012-02-24 23:00:38Z ottenhoff@longsight.com $
 ***********************************************************************************
 *
 * Copyright (c) 2007, 2008 The Sakai Foundation
 *
 * Licensed under the Educational Community 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.opensource.org/licenses/ECL-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 org.sakaiproject.assignment.taggable.tool;

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

import org.sakaiproject.taggable.api.Tag;
import org.sakaiproject.taggable.api.TagColumn;
import org.sakaiproject.taggable.api.TagList;
import org.sakaiproject.taggable.api.TaggableActivity;
import org.sakaiproject.taggable.api.TaggingProvider;

/**
 * Wrapper around {@link TaggingProvider} for displaying a pageable/sortable
 * list of tags for an activity or item. Since there may be multiple providers
 * each with a list of tags displayed on a single page, this class enables each
 * provider to maintain the page/sort state of its list separate from others.
 * 
 * @author The Sakai Foundation.
 */
public class DecoratedTaggingProvider {
	TaggingProvider provider;

	Sort sort;

	Pager pager;

	TaggableActivity lastActivity;

	TagList tagList;

	protected final static int[] PAGESIZES = { 5, 10, 20, 50, 100, 200 };

	public DecoratedTaggingProvider(TaggingProvider provider) {
		this.provider = provider;
		sort = new Sort("", true);
	}

	public TaggingProvider getProvider() {
		return provider;
	}

	public Sort getSort() {
		return sort;
	}

	public Pager getPager() {
		return pager;
	}

	protected TagList getTagList(TaggableActivity activity) {
		if (!activity.equals(lastActivity)) {
			sort = new Sort("", true);
			pager = null;
			tagList = null;
			lastActivity = activity;
		}
		if (tagList == null) {
			tagList = provider.getTags(activity);
		}
		return tagList;
	}

	public List<TagColumn> getColumns(TaggableActivity activity) {
		return getTagList(activity).getColumns();
	}

	public List<Tag> getTags(TaggableActivity activity) {
		TagList list = getTagList(activity);
		List<Tag> tags = new ArrayList<Tag>();
		if (pager == null) {
			pager = new Pager((list == null) ? 0 : list.size(), 0, 20);
		}
		if (list != null) {
			list.sort(list.getColumn(sort.getSort()), sort.isAscending());
			tags = list
					.subList(pager.getFirstItem(), pager.getLastItemNumber());
		}
		return tags;
	}

	public class Sort {

		protected String sortString = "";

		protected boolean ascending = true;

		public Sort(String sort, boolean ascending) {
			sortString = sort;
			this.ascending = ascending;
		}

		public boolean isAscending() {
			return ascending;
		}

		public void setAscending(boolean ascending) {
			this.ascending = ascending;
		}

		public String getSort() {
			return sortString;
		}

		public void setSort(String sort) {
			sortString = sort;
		}
	}

	public class Pager {

		protected int totalItems;

		protected int firstItem;

		protected int pageSize;

		public static final String FIRST = "|<", PREVIOUS = "<", NEXT = ">",
				LAST = ">|";

		public Pager(int totalItems, int firstItem, int pageSize) {
			this.totalItems = totalItems;
			this.firstItem = firstItem;
			this.pageSize = pageSize;
		}

		public int getFirstItemNumber() {
			return firstItem + 1;
		}

		public int getLastItemNumber() {
			int n = firstItem + pageSize;
			return (totalItems < n ? totalItems : n);
		}

		public boolean canFirst() {
			return firstItem > 0;
		}

		public boolean canPrevious() {
			return canFirst();
		}

		public boolean canNext() {
			return getLastItemNumber() < totalItems;
		}

		public boolean canLast() {
			return canNext();
		}

		public int[] getPageSizes() {
			return PAGESIZES;
		}

		public int getFirstItem() {
			return firstItem;
		}

		public void setFirstItem(int firstItem) {
			this.firstItem = firstItem;
		}

		public int getPageSize() {
			return pageSize;
		}

		public void setPageSize(int pageSize) {
			this.pageSize = pageSize;
		}

		public int getTotalItems() {
			return totalItems;
		}

		public void setTotalItems(int totalItems) {
			this.totalItems = totalItems;
		}
	}
}