RetypingFeatureCollection.java

/* Copyright (c) 2001 - 2007 TOPP - www.openplans.org. All rights reserved.
 * This code is licensed under the GPL 2.0 license, availible at the root
 * application directory.
 */
package org.geoserver.feature;

import java.io.IOException;
import java.util.Iterator;
import java.util.NoSuchElementException;

import org.geotools.data.FeatureReader;
import org.geotools.data.FeatureWriter;
import org.geotools.data.simple.SimpleFeatureCollection;
import org.geotools.data.simple.SimpleFeatureIterator;
import org.geotools.feature.IllegalAttributeException;
import org.geotools.feature.collection.DelegateSimpleFeatureIterator;
import org.geotools.feature.simple.SimpleFeatureBuilder;
import org.geotools.filter.identity.FeatureIdImpl;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.feature.type.AttributeDescriptor;
import org.opengis.filter.identity.FeatureId;

/**
 * FeatureCollection with "casts" features from on feature type to another.
 * 
 * @author Justin Deoliveira, The Open Planning Project, jdeolive@openplans.org
 * 
 */
public class RetypingFeatureCollection extends DecoratingFeatureCollection {
    SimpleFeatureType target;

    public RetypingFeatureCollection(SimpleFeatureCollection delegate,
            SimpleFeatureType target) {
        super(delegate);
        this.target = target;
    }

    public SimpleFeatureType getSchema() {
        return target;
    }

    public Iterator<SimpleFeature> iterator() {
        return new RetypingIterator(delegate.iterator(), target);
    }

    public void close(Iterator<SimpleFeature> iterator) {
        RetypingIterator retyping = (RetypingIterator) iterator;
        delegate.close(retyping.delegate);
    }

    public SimpleFeatureIterator features() {
        return new DelegateSimpleFeatureIterator(this, iterator());
    }

    public void close(SimpleFeatureIterator iterator) {
        DelegateSimpleFeatureIterator delegate = (DelegateSimpleFeatureIterator) iterator;
        delegate.close();
    }

    static SimpleFeature retype(SimpleFeature source, SimpleFeatureBuilder builder)
            throws IllegalAttributeException {
        SimpleFeatureType target = builder.getFeatureType();
        for (int i = 0; i < target.getAttributeCount(); i++) {
            AttributeDescriptor attributeType = target.getDescriptor(i);
            Object value = null;

            if (source.getFeatureType().getDescriptor(attributeType.getName()) != null) {
                value = source.getAttribute(attributeType.getName());
            }

            builder.add(value);
        }

        FeatureId id = reTypeId(source.getIdentifier(), source.getFeatureType(), target);
        SimpleFeature retyped = builder.buildFeature(id.getID());
        retyped.getUserData().putAll(source.getUserData());
        return  retyped;
    }

    /**
     * Given a feature id following the <typename>.<internalId> convention, the
     * original type and the destination type, this converts the id from
     * <original>.<internalid> to <target>.<internalid>
     * 
     * @param id
     * @param original
     * @param target
     * @return
     */
    public static FeatureId reTypeId(FeatureId sourceId, SimpleFeatureType original,
            SimpleFeatureType target) {
        final String originalTypeName = original.getName().getLocalPart();
        final String destTypeName = target.getName().getLocalPart();
        if (destTypeName.equals(originalTypeName))
            return sourceId;

        final String prefix = originalTypeName + ".";
        if (sourceId.getID().startsWith(prefix)) {
            return new FeatureIdImpl(destTypeName + "." + sourceId.getID().substring(prefix.length()));
        } else
            return sourceId;
    }

    public static class RetypingIterator implements Iterator<SimpleFeature> {
        SimpleFeatureBuilder builder;
        Iterator<SimpleFeature> delegate;

        public RetypingIterator(Iterator<SimpleFeature> delegate, SimpleFeatureType target) {
            this.delegate = delegate;
            this.builder = new SimpleFeatureBuilder(target);
        }

        public boolean hasNext() {
            return delegate.hasNext();
        }

        public SimpleFeature next() {
            try {
                return RetypingFeatureCollection.retype(delegate.next(), builder);
            } catch (IllegalAttributeException e) {
                throw new RuntimeException(e);
            }
        }

        public void remove() {
            delegate.remove();
        }
    }

    public static class RetypingFeatureReader implements
            FeatureReader<SimpleFeatureType, SimpleFeature> {
        FeatureReader<SimpleFeatureType, SimpleFeature> delegate;
        SimpleFeatureBuilder builder;

        public RetypingFeatureReader(FeatureReader<SimpleFeatureType, SimpleFeature> delegate,
                SimpleFeatureType target) {
            this.delegate = delegate;
            this.builder = new SimpleFeatureBuilder(target);
        }

        public void close() throws IOException {
            delegate.close();
            delegate = null;
            builder = null;
        }

        public SimpleFeatureType getFeatureType() {
            return builder.getFeatureType();
        }

        public boolean hasNext() throws IOException {
            return delegate.hasNext();
        }

        public SimpleFeature next() throws IOException, IllegalAttributeException,
                NoSuchElementException {
            return RetypingFeatureCollection.retype(delegate.next(), builder);
        }
    }

    public static class RetypingFeatureWriter implements
            FeatureWriter<SimpleFeatureType, SimpleFeature> {
        FeatureWriter<SimpleFeatureType, SimpleFeature> delegate;

        SimpleFeatureBuilder builder;

        private SimpleFeature current;

        private SimpleFeature retyped;

        public RetypingFeatureWriter(FeatureWriter<SimpleFeatureType, SimpleFeature> delegate,
                SimpleFeatureType target) {
            this.delegate = delegate;
            this.builder = new SimpleFeatureBuilder(target);
        }

        public void close() throws IOException {
            delegate.close();
            delegate = null;
            builder = null;
        }

        public SimpleFeatureType getFeatureType() {
            return builder.getFeatureType();
        }

        public boolean hasNext() throws IOException {
            return delegate.hasNext();
        }

        public SimpleFeature next() throws IOException {
            try {
                current = delegate.next();
                retyped = RetypingFeatureCollection.retype(current, builder);
                return retyped;
            } catch (IllegalAttributeException e) {
                throw (IOException) new IOException("Error occurred while retyping feature")
                        .initCause(e);
            }
        }

        public void remove() throws IOException {
            delegate.write();
        }

        public void write() throws IOException {
            try {
                SimpleFeatureType target = getFeatureType();
                for (int i = 0; i < target.getAttributeCount(); i++) {
                    AttributeDescriptor at = target.getDescriptor(i);
                    Object value = retyped.getAttribute(i);
                    current.setAttribute(at.getLocalName(), value);
                }
                delegate.write();
            } catch (IllegalAttributeException e) {
                throw (IOException) new IOException("Error occurred while retyping feature")
                        .initCause(e);
            }
        }
    }
}