/* (c) 2014 Open Source Geospatial Foundation - all rights reserved
 * (c) 2001 - 2013 OpenPlans
 * This code is licensed under the GPL 2.0 license, available at the root
 * application directory.
 */
package org.geoserver.wms.georss;

import java.io.IOException;
import java.text.DateFormat;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.List;
import java.util.TimeZone;

import org.geoserver.ows.URLMangler.URLType;
import org.geoserver.ows.util.ResponseUtils;
import org.geoserver.wms.WMS;
import org.geoserver.wms.WMSMapContent;
import org.geoserver.wms.WMSRequests;
import org.geoserver.wms.featureinfo.FeatureTemplate;
import org.geotools.map.Layer;
import org.opengis.feature.simple.SimpleFeature;

/**
 * The AtomUtils class provides some static methods useful in producing atom metadata related to 
 * GeoServer features.
 *
 * @author David Winslow
 */
public final class AtomUtils {

    /**
     * A date formatting object that does most of the formatting work for RFC3339.  Note that since 
     * Java's SimpleDateFormat does not provide all the facilities needed for RFC3339 there is still
     * some custom code to finish the job.
     */
    private static DateFormat rfc3339 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");

    /**
     * A number formatting object to format the the timezone offset info in RFC3339 output.
     */
    private static NumberFormat doubleDigit = new DecimalFormat("00");

    /**
     * A FeatureTemplate used for formatting feature info.
     * @TODO: Are these things threadsafe?
     */
    private static FeatureTemplate featureTemplate = new FeatureTemplate();

    /**
     * This is a utility class so don't allow instantiation.
     */
    private AtomUtils(){ /* Nothing to do */ }

    /**
     * Format dates as specified in rfc3339 (required for Atom dates)
     * @param d the Date to be formatted
     * @return the formatted date
     */
    public static String dateToRFC3339(Date d){
        StringBuilder result = new StringBuilder(rfc3339.format(d));
        Calendar cal = new GregorianCalendar();
        cal.setTime(d);
        cal.setTimeZone(TimeZone.getDefault());
        int offset_millis = cal.get(Calendar.ZONE_OFFSET) + cal.get(Calendar.DST_OFFSET);
        int offset_hours = Math.abs(offset_millis / (1000 * 60 * 60));
        int offset_minutes = Math.abs((offset_millis / (1000 * 60)) % 60);

        if (offset_millis == 0) {
            result.append("Z");
        } else {
            result
                .append((offset_millis > 0) ? "+" : "-")
                .append(doubleDigit.format(offset_hours))
                .append(":")
                .append(doubleDigit.format(offset_minutes));
        }

        return result.toString();
    }

    //TODO: use an html based output format
    public static String getEntryURL(WMS wms, SimpleFeature feature, WMSMapContent context){
        try {
            return featureTemplate.link(feature);
        } catch (IOException ioe){
            String nsUri = feature.getType().getName().getNamespaceURI();
            String nsPrefix = wms.getNameSpacePrefix(nsUri);

            HashMap<String,String> params = new HashMap<String,String>();
            params.put("format", "application/atom+xml");
            params.put("layers",  nsPrefix + ":" + feature.getType().getTypeName());
            params.put("featureid", feature.getID());
         
            return ResponseUtils.buildURL(context.getRequest().getBaseUrl(),
                    "wms/reflect",
                    params,
                    URLType.SERVICE);
        }
    }

    public static String getEntryURI(WMS wms, SimpleFeature feature, WMSMapContent context){
        return getEntryURL(wms, feature, context);
    }

    public static String getFeatureTitle(SimpleFeature feature){
        try{
            return featureTemplate.title(feature);
        } catch (IOException ioe){
            return feature.getID();
        }
    }

    public static String getFeatureDescription(SimpleFeature feature){
        try{
            return featureTemplate.description(feature);
        } catch (IOException ioe) {
            return feature.getID();
        }
    }

    public static String getFeedURL(WMSMapContent context){
        return WMSRequests.getGetMapUrl(context.getRequest(), null, 0, null, null).replace(' ', '+');
    }

    public static String getFeedURI(WMSMapContent context){
        return getFeedURL(context);
    }

    public static String getFeedTitle(WMSMapContent context){
        StringBuffer title = new StringBuffer();
        for( Layer layer : context.layers() ){
            title.append(layer.getTitle()).append(",");
        }
        title.setLength(title.length()-1);
        return title.toString();
    }

    public static String getFeedDescription(WMSMapContent context) {
        StringBuffer description = new StringBuffer();
        for (Layer layer : context.layers()) {
            description.append(layer.getUserData().get("abstract")).append("\n");
        }
        if (description.length() == 0) {
            return "Auto-generated by geoserver";
        } else {
            description.setLength(description.length() - 1);
            return description.toString();
        }
    }


    private static String commaSeparatedLayers(WMSMapContent con){
        StringBuilder layers = new StringBuilder();
        List<Layer> mapLayers = con.layers();
        for (int i = 0; i < mapLayers.size(); i++){
            layers.append(mapLayers.get(i).getTitle());
            if (i < mapLayers.size() - 1) layers.append(",");
        }
        return layers.toString();
    }
}