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/* gvSIG. Geographic Information System of the Valencian Government

*

* Copyright (C) 2007-2008 Infrastructures and Transports Department

* of the Valencian Government (CIT)

*

* This program is free software; you can redistribute it and/or

* modify it under the terms of the GNU General Public License

* as published by the Free Software Foundation; either version 2

* of the License, or (at your option) any later version.

*

* This program is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

* GNU General Public License for more details.

*

* You should have received a copy of the GNU General Public License

* along with this program; if not, write to the Free Software

* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

* MA  02110-1301, USA.

*

*/

/*

* AUTHORS (In addition to CIT):

* 2008 {{Company}}   {{Task}}

*/

package org.gvsig.fmap.dal.feature.impl;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import org.gvsig.fmap.dal.exceptions.DataException;

import org.gvsig.fmap.dal.feature.FeatureIndex;

import org.gvsig.fmap.dal.feature.FeatureIndexes;

import org.gvsig.fmap.dal.feature.exceptions.FeatureIndexException;

import org.gvsig.fmap.dal.feature.spi.FeatureSetProvider;

import org.gvsig.fmap.dal.feature.spi.index.FeatureIndexProviderServices;

import org.gvsig.tools.evaluator.Evaluator;

import org.gvsig.tools.evaluator.EvaluatorFieldValue;

/**

 * This class provides access to a FeatureStore local indexes and also

 * decides which index to use given an evaluator containing the filter expression.

 * 

 * @author jyarza

 */ 

public class DefaultFeatureIndexes implements FeatureIndexes {

        // Access by index name

        private Map names;

        // Store to which this belongs

        private DefaultFeatureStore store;

        /**

         * Creates an empty DataIndexes for the given FeatureStore

         *

         * @param store

         *            FeatureStore to whom this belongs

         * @throws DataException

         */

        public DefaultFeatureIndexes(DefaultFeatureStore store)

                        throws DataException {

                names = new HashMap();

                this.store = store;

        }

        /* (non-Javadoc)

         * @see org.gvsig.fmap.dal.index.DataIndexes#getDataIndex(java.lang.String)

         */

        public FeatureIndex getFeatureIndex(String name) {

                return (FeatureIndex) names.get(name);

        }

        /* (non-Javadoc)

         * @see org.gvsig.fmap.dal.index.DataIndexes#addIndex(org.gvsig.fmap.dal.feature.FeatureType, java.lang.String, org.gvsig.fmap.dal.feature.DataIndex)

         */

        public void addIndex(FeatureIndexProviderServices index) {

                // By name

                names.put(index.getName(), index);

        }

        public Iterator iterator() {

                return names.values().iterator();

        }

        /**

         * Using the given evaluator attributes, choose and use an appropriate index 

         * to obtain a FeatureSetProvider. If no index can be applied, then this method returns null

         * 

         * @param evaluator

         * @return FeatureSetProvider or null if could not find any appropriate index.

         * 

         */

        public FeatureSetProvider getFeatureSet(Evaluator evaluator) {

                class ApplyIndex {

                        DefaultFeatureIndex index;

                        EvaluatorFieldValue[] data;

                        ApplyIndex(DefaultFeatureIndex index, EvaluatorFieldValue[] data) {

                                this.index = index;

                                this.data = data;

                        }

                        /**

                         * Checks whether the index supports the evaluator request

                         * @return

                         */

                        boolean isSupported() {

                                switch(data[0].getType()) {

                                case EvaluatorFieldValue.MATCH:

                                        return index.getFeatureIndexProvider().isMatchSupported();

                                case EvaluatorFieldValue.NEAREST:

                                        return index.getFeatureIndexProvider().isNearestSupported();

                                case EvaluatorFieldValue.RANGE:

                                        return index.getFeatureIndexProvider().isRangeSupported();

                                default:

                                        return false;

                                }

                        }

                        /**

                         * Applies the index using the evaluator fields

                         * @return FeatureSetProvider with the result

                         * @throws FeatureIndexException

                         */

                        FeatureSetProvider apply() throws FeatureIndexException {

                                switch (data[0].getType()) {

                                case EvaluatorFieldValue.MATCH:

                                        return index.getMatchFeatureSet(data[0].getValue());

                                case EvaluatorFieldValue.RANGE:

                                        return index.getRangeFeatureSet(data[0].getValue1(),

                                                        data[0].getValue2());

                                case EvaluatorFieldValue.NEAREST:

                                        if ((data[0].getTolerance() == -1) || (!isSupported()) ) {

                                                return index.getNearestFeatureSet(data[0]

                                                                .getCount(), data[0].getValue());

                                        } else {

                                                return index.getNearestFeatureSet(data[0].getCount(), data[0].getValue(), data[0].getTolerance());

                                        }

                                }

                                return null;

                        }

                }

                // Select applicable indexes

                try {

                        List applyIndexes = new ArrayList();

                        Iterator indexes = this.iterator();

                        while (indexes.hasNext()) {

                                DefaultFeatureIndex index = (DefaultFeatureIndex) indexes

                                                .next();

                                String[] attrs = (String[])index.getAttributeNames().toArray();

                                for (int i = 0; i < attrs.length; i++) {

                                        String attrname = attrs[i];

                                        EvaluatorFieldValue[] values = evaluator

                                                        .getFieldValues(attrname);

                                        if (values != null) {

                                                applyIndexes.add(new ApplyIndex(index, values));

                                                break;

                                        }

                                }

                        }

                        // If there's not any applicable index, return null

                        if (applyIndexes.size() == 0) return null;

                        // Lookup an index with support for the requested function

                        Iterator it = applyIndexes.iterator();

                        ApplyIndex index = (ApplyIndex) it.next();

                        while ( it.hasNext() && (!index.isSupported()) ) {

                                index = (ApplyIndex) it.next();

                        }

                        // If there is not any any index supporting the function, use the first one

                        if (!index.isSupported()) {

                                this.store.getLogger().info("No index support for the evaluator values. Using default index.");

                                index = (ApplyIndex) applyIndexes.get(0);

                        }

                        // Apply index

                        return index.apply();

                } catch (Exception e) {

                        this.store.getLogger().error("Error searching for an index to apply.",

                                        e);

                        return null;

                }

        }

}