DefaultViewersManager.java

/**
 *  Copyright 2012 Universitat Pompeu Fabra.
 *
 *  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 org.onexus.ui.api.viewers;

import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.Predicate;
import org.onexus.resource.api.Resource;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class DefaultViewersManager implements IViewersManager {

    public static final ViewerCreatorComparator VIEWER_CREATOR_COMPRATOR = new ViewerCreatorComparator();

    private List<IViewerCreator> viewerCreators;

    public DefaultViewersManager() {
        super();
    }

    @Override
    public List<IViewerCreator> getViewerCreators(Resource resource) {

        if (resource == null) {
            return Collections.emptyList();
        }

        List<IViewerCreator> result = new ArrayList<IViewerCreator>();
        CollectionUtils.select(viewerCreators, new VisiblePredicate(resource), result);
        Collections.sort(result, VIEWER_CREATOR_COMPRATOR);

        return result;

    }

    public List<IViewerCreator> getViewerCreators() {
        return viewerCreators;
    }

    public void setViewerCreators(List<IViewerCreator> viewerCreators) {
        this.viewerCreators = viewerCreators;
    }

    private static class VisiblePredicate implements Predicate, Serializable {

        private Resource resource;

        public VisiblePredicate(Resource resource) {
            super();
            this.resource = resource;
        }

        @Override
        public boolean evaluate(Object object) {

            if (object instanceof IViewerCreator) {
                IViewerCreator creator = (IViewerCreator) object;

                if (resource == null) {
                    return false;
                }

                return creator.isVisible(resource.getClass());
            }

            return false;
        }

    }

    private static class ViewerCreatorComparator implements Comparator<IViewerCreator> {

        @Override
        public int compare(IViewerCreator o1, IViewerCreator o2) {
            return Double.compare(o1.getOrder(), o2.getOrder());
        }

    }

}