/** Copyright (C) 2017 by Bundesanstalt für Gewässerkunde
 * Software engineering by
 *  Björnsen Beratende Ingenieure GmbH
 *  Dr. Schumacher Ingenieurbüro für Wasser und Umwelt
 *
 * This file is Free Software under the GNU AGPL (>=v3)
 * and comes with ABSOLUTELY NO WARRANTY! Check out the
 * documentation coming with Dive4Elements River for details.
 */
package org.dive4elements.river.artifacts.uinfo.inundationduration;

import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.Arrays;
import java.util.List;
import java.util.Map;

import javax.imageio.ImageIO;

import org.dive4elements.artifactdatabase.rest.BaseResource;
import org.restlet.Client;
import org.restlet.Context;
import org.restlet.Request;
import org.restlet.Response;
import org.restlet.data.Form;
import org.restlet.data.MediaType;
import org.restlet.data.Method;
import org.restlet.data.Protocol;
import org.restlet.data.Reference;
import org.restlet.data.Status;
import org.restlet.representation.OutputRepresentation;
import org.restlet.representation.Representation;
import org.restlet.resource.ResourceException;

/**
 * Proof of context wms proxy.
 *
 * @author Gernot Belger
 */
public class VegetationWmsResource extends BaseResource {

    public static final String BASE_PATH = "vegetationWms";

    private static final String ATTRIBUTE_VEGETATION_ARTIFACT_UUID = "vegetation-artifact-uuid";

    private static final String ATTRIBUTE_WMS_URL = "wmsUrl";

    private static final ThreadLocal<Client> CLIENT = new ThreadLocal<Client>() {
        @Override
        protected Client initialValue() {

            final List<Protocol> protocols = Arrays.asList(Protocol.HTTPS, Protocol.HTTP);
            final Client client = new Client(new Context(), protocols);
            // FIXME
            /* Nachfolgende 2 Zeilen sind nur für die BCE-Entwicklungsumgebung bestimmt */
            // client.getContext().getParameters().add("proxyHost", "proxy.bce01.de");
            // client.getContext().getParameters().add("proxyPort", "8080");
            return client;
        }
    };

    @Override
    protected Representation innerGet() throws ResourceException {

        try {
            final Request request = getRequest();

            final Map<String, Object> attributes = request.getAttributes();
            final String vegArtifactUuid = (String) attributes.get(ATTRIBUTE_VEGETATION_ARTIFACT_UUID);
            final String baseUrl = (String) attributes.get(ATTRIBUTE_WMS_URL);

            final Reference originalRef = request.getOriginalRef();
            final String query = originalRef.getQuery();

            final Form queryAsForm = originalRef.getQueryAsForm();
            final boolean isGetMap = "GetMap".equalsIgnoreCase(queryAsForm.getFirstValue("REQUEST", true));

            final String decodedBaseUrl = URLDecoder.decode(baseUrl, "UTF-8");

            final Reference proxyReference = new Reference(decodedBaseUrl);
            proxyReference.setQuery(query);

            final Client client = CLIENT.get();

            final Request proxyRequest = new Request(Method.GET, proxyReference);
            final Response response = client.handle(proxyRequest);

            final Status status = response.getStatus();

            if (!Status.SUCCESS_OK.equals(status))
                throw new ResourceException(status);

            final Representation entity = response.getEntity();

            /* simply redirect everything that is not an png image */
            if (!isGetMap)
                return entity;

            final MediaType mediaType = entity.getMediaType();
            if (!MediaType.IMAGE_ALL.getMainType().equals(mediaType.getMainType()))
                return entity;

            try {
                final BufferedImage image = ImageIO.read(entity.getStream());

                // FIXME: tweak image...
                final WritableRaster raster = image.getRaster();
                final int width = raster.getWidth();
                final int height = raster.getHeight();
                final int numBands = raster.getNumBands();
                for (int x = 0; x < width; x++) {
                    for (int y = 0; y < height; y++) {

                        // final double sampleDouble = raster.getSampleDouble(x, y, 0);

                        final int red = raster.getSample(x, y, 0);
                        final int green = raster.getSample(x, y, 1);
                        final int blue = raster.getSample(x, y, 2);
                        final int alpha = raster.getSample(x, y, 3);

                        raster.setSample(x, y, 0, green);
                        raster.setSample(x, y, 1, red);
                        raster.setSample(x, y, 2, blue);
                        raster.setSample(x, y, 3, alpha);
                    }
                }

                final Representation newResponse = new OutputRepresentation(mediaType) {

                    @Override
                    public void write(final OutputStream outputStream) throws IOException {

                        // REMARK: in most cases the media-subtype can be used as image-format name.
                        final String subType = mediaType.getSubType();
                        ImageIO.write(image, subType, outputStream);

                    }
                };

                return newResponse;
            }
            catch (final IOException e) {
                e.printStackTrace();
                throw new ResourceException(Status.SERVER_ERROR_INTERNAL, e);
            }

        }
        catch (final UnsupportedEncodingException e) {
            e.printStackTrace();
            throw new ResourceException(Status.CLIENT_ERROR_BAD_REQUEST, e);
        }
    }
}