package de.intevation.flys.client.server;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.StringWriter;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;

import org.apache.log4j.Logger;

import com.google.gwt.user.server.rpc.RemoteServiceServlet;


import de.intevation.flys.client.shared.exceptions.ServerException;
import de.intevation.flys.client.shared.model.AttributedTheme;
import de.intevation.flys.client.shared.model.Theme;

import de.intevation.flys.client.client.services.GFIService;


/**
 * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
 */
public class GFIServiceImpl
extends      RemoteServiceServlet
implements   GFIService
{
    public static final String ERR_NO_VALID_GFI_URL =
        "error_no_valid_gfi_url";

    public static final String ERR_GFI_REQUEST_FAILED =
        "error_gfi_req_failed";

    public static final String ERR_PARSING_RESPONSE_FAILED =
        "error_gfi_parsing_failed";


    private static final Logger logger =
        Logger.getLogger(GFIServiceImpl.class);


    /**
     * @param themes
     * @param format
     * @param bbox
     * @param height
     * @param width
     * @param x
     * @param y
     *
     * @return
     */
    public String query(
        List<Theme> themes,
        String      format,
        String      bbox,
        String      projection,
        int         height,
        int         width,
        int         x,
        int         y
    ) throws ServerException
    {
        logger.info("GFIServiceImpl.query");

        String path = createGetFeautureInfoURL(
            themes, format, bbox, projection, height, width, x, y);
        logger.debug("URL=" + path);

        try {
            URL url = new URL(path);

            URLConnection conn = url.openConnection();
            conn.connect();

            InputStream is = conn.getInputStream();

            return getResponseText(is);

        }
        catch (IOException ioe) {
            logger.warn(ioe, ioe);
        }

        throw new ServerException(ERR_GFI_REQUEST_FAILED);
    }


    protected String getResponseText(InputStream is)
    throws ServerException {
        BufferedReader reader = null;
        StringWriter   writer = new StringWriter();

        try {
            reader = new BufferedReader(new InputStreamReader(is));

            String line = null;

            if (reader.ready()) {
                while ((line = reader.readLine()) != null) {
                    String test = line.trim();
                    if (test.startsWith("<") && !test.startsWith("</") 
                        && test.indexOf("_feature") > 0)
                    {
                        writer.append("<gml:featureMember>");
                    }
                    writer.append(line);

                    if (test.startsWith("</") && test.indexOf("_feature") > 0) {
                        writer.append("</gml:featureMember>");
                    }
                }
            }
        }
        catch (IOException ioe) {
            logger.warn(ioe, ioe);
            throw new ServerException(ERR_PARSING_RESPONSE_FAILED);
        }
        finally {
            if (reader != null) {
                try {
                    reader.close();
                }
                catch (IOException ioe) {
                    // do nothing here
                }
            }
        }

        return writer.toString();
    }


    /**
     * @param map
     * @param themes
     * @param format
     * @param x
     * @param y
     *
     * @return
     */
    protected String createGetFeautureInfoURL(
        List<Theme> themes,
        String      infoFormat,
        String      bbox,
        String      projection,
        int         height,
        int         width,
        int         x,
        int         y
    ) throws ServerException
    {
        String url = getUrl(themes);

        if (url == null || url.length() == 0) {
            throw new ServerException(ERR_NO_VALID_GFI_URL);
        }

        String layers = createLayersString(themes);

        StringBuilder sb = new StringBuilder();
        sb.append(url);

        if (url.indexOf("?") < 0) {
            sb.append("?SERVICE=WMS");
        }
        else {
            sb.append("&SERVICE=WMS");
        }

        sb.append("&VERSION=1.1.1");
        sb.append("&REQUEST=GetFeatureInfo");
        sb.append("&LAYERS=" + layers);
        sb.append("&QUERY_LAYERS=" + layers);
        sb.append("&BBOX=" + bbox);
        sb.append("&HEIGHT=" + height);
        sb.append("&WIDTH=" + width);
        sb.append("&FORMAT=image/png");
        sb.append("&INFO_FORMAT=" + infoFormat);
        sb.append("&SRS=" + projection);
        sb.append("&X=" + String.valueOf(x));
        sb.append("&Y=" + String.valueOf(y));

        return sb.toString();
    }


    protected String getUrl(List<Theme> themes) {
        for (Theme t: themes) {
            AttributedTheme attr = (AttributedTheme) t;

            if (attr.getAttrAsBoolean("queryable")) {
                return attr.getAttr("url");
            }
        }

        return null;
    }


    protected String createLayersString(List<Theme> themes) {
        StringBuilder sb = new StringBuilder();
        boolean first = true;

        for (Theme theme: themes) {
            if (!first) {
                sb.append(",");
            }

            AttributedTheme layer = (AttributedTheme) theme;
            if (layer.getAttrAsBoolean("queryable")) {
                sb.append(layer.getAttr("layers"));
                first = false;
            }
        }

        return sb.toString();
    }
}
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