package org.geotoolkit.pending.demo.tree;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.StandardOpenOption;
import java.util.HashMap;
import java.util.Map;
import org.apache.sis.geometry.GeneralEnvelope;
import org.geotoolkit.index.tree.ChannelTreeElementMapper;
import org.opengis.geometry.Envelope;
import org.opengis.referencing.crs.CoordinateReferenceSystem;

/**
 * Create a FileTreeElementMapper adapted for Tree demo.
 *
 * @author Remi Marechal (Geomatys).
 */
final class DemoFileTreeElementMapper extends ChannelTreeElementMapper<Envelope>{

    final private CoordinateReferenceSystem crs;
    final private int dimension;


    DemoFileTreeElementMapper(File output, final CoordinateReferenceSystem crs) throws IOException {
        super(Files.newByteChannel(output.toPath(), StandardOpenOption.CREATE, StandardOpenOption.READ, StandardOpenOption.WRITE), (crs.getCoordinateSystem().getDimension()*2*Double.SIZE) /8);
        this.crs       = crs;
        this.dimension = crs.getCoordinateSystem().getDimension();
    }


    @Override
    protected void writeObject(Envelope Object) throws IOException {
        /*
         * To store element on hard drive we use a Databuffer where all
         * databuffer working has been already manage.
         * User should just write element what he need to define a data, from databuffer from superclass as below.
         *
         * In this case, we travel all dimensions from envelope coordinate system and we write envelope coordinates.
         */
        for (int d = 0; d < dimension; d++) {
            super.byteBuffer.putDouble(Object.getMinimum(d));
            super.byteBuffer.putDouble(Object.getMaximum(d));
        }
        /*
         * In our case Envelope is just define by its coordinates and its crs but
         * user may want store other information as he need.
         */
    }

    @Override
    protected Envelope readObject() throws IOException {
        /*
         * Same operation as writing action in reversed order.
         */
        GeneralEnvelope resultEnvelop = new GeneralEnvelope(crs);
        for (int d = 0; d < dimension; d++) {
            final double mind = super.byteBuffer.getDouble();
            final double maxd = super.byteBuffer.getDouble();
            resultEnvelop.setRange(d, mind, maxd);
        }
        return resultEnvelop;
    }

    @Override
    protected boolean areEquals(Envelope objectA, Envelope objectB) {
        /*
         * In some case equals method is not in accordance with equality pertinence asked by user.
         * User may redefine equal made.
         */
        return objectA.equals(objectB);
    }

    @Override
    public Envelope getEnvelope(Envelope object) throws IOException {
        return object;
    }

    @Override
    public Map<Integer, Envelope> getFullMap() throws IOException {
        return new HashMap<>();
    }
}