/* 
 * Copyright (c) 2001 - 20089 TOPP - www.openplans.org. All rights reserved.
 * This code is licensed under the GPL 2.0 license, available at the root
 * application directory.
 */

package org.geoserver.template;

import java.util.LinkedList;
import java.util.List;
import org.geotools.feature.FeatureCollection;
import org.geotools.feature.FeatureIterator;
import freemarker.ext.beans.BeansWrapper;
import freemarker.template.TemplateCollectionModel;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;
import freemarker.template.TemplateModelIterator;

/**
 * 
 * Create FeatureCollection Template Model without copying features to memory
 * When using this in a FeatureWrapper, it is necessary to call purge() method after
 * processing template, to close any open database connections
 * 
 * @author Niels Charlier, Curtin University of Technology
 * 
 */
public class DirectTemplateFeatureCollectionFactory implements FeatureWrapper.TemplateFeatureCollectionFactory {

    protected List<FeatureIterator> openIterators = new LinkedList<FeatureIterator>();

    public void purge() {
        while (!openIterators.isEmpty()) {
            openIterators.get(0).close();
            openIterators.remove(0);
        }
    }

    public TemplateCollectionModel createTemplateFeatureCollection(FeatureCollection collection,
            BeansWrapper wrapper) {
        return new TemplateFeatureCollection(collection, wrapper);
    }

    protected class TemplateFeatureCollection implements TemplateCollectionModel {
        protected BeansWrapper wrapper;

        protected FeatureCollection collection;

        public TemplateFeatureCollection(FeatureCollection collection, BeansWrapper wrapper) {
            this.collection = collection;
            this.wrapper = wrapper;
        }

        public TemplateModelIterator iterator() throws TemplateModelException {
            return new TemplateFeatureIterator(collection.features(), wrapper);
        }

    }

    protected class TemplateFeatureIterator implements TemplateModelIterator {

        protected BeansWrapper wrapper;

        protected FeatureIterator iterator;

        public TemplateFeatureIterator(FeatureIterator iterator, BeansWrapper wrapper) {
            this.iterator = iterator;
            this.wrapper = wrapper;
        }

        public TemplateModel next() throws TemplateModelException {
            return wrapper.wrap(iterator.next());
        }

        public boolean hasNext() throws TemplateModelException {
            return iterator.hasNext();
        }

    }

}