package de.intevation.flys.artifacts.model;

import java.util.ArrayList;
import java.util.List;

import java.math.BigDecimal;

import net.sf.ehcache.Cache;
import net.sf.ehcache.Element;

import org.apache.log4j.Logger;

import org.hibernate.Query;
import org.hibernate.Session;

import de.intevation.flys.model.HYKFormation;
import de.intevation.flys.model.HYKFlowZone;

import de.intevation.flys.artifacts.cache.CacheFactory;

import de.intevation.flys.backend.SessionHolder;


/**
 * Factory to access HYKs (hydrographic values).
 */
public class HYKFactory
{
    private static Logger logger = Logger.getLogger(HYKFactory.class);

    public static String HYK_CACHE_NAME = "hykache";


    /** Do not instantiate a HYKFactory. */
    private HYKFactory() {
    }


    /**
     * Get List of Zones for given river and km.
     */
    public static Object getHYKs(int riverId, double km) {
        logger.debug("HYKFactory.getHYKs");

        Cache cache = CacheFactory.getCache(HYK_CACHE_NAME);

        String cacheKey;

        if (cache != null) {
            cacheKey = "" + riverId + "_" + km;
            Element element = cache.get(cacheKey);
            if (element != null) {
                logger.debug("Got hyk from cache");
                return (List<Zone>)element.getValue();
            }
        }
        else {
            cacheKey = null;
        }

        List<Zone> zones = getZonesUncached(riverId, km);

        if (zones != null && cacheKey != null) {
            logger.debug("Store hykzones in cache.");
            Element element = new Element(cacheKey, zones);
            cache.put(element);
        }

        return zones;
    }


    /**
     * 
     * @param column the position columns value
     * @param wst_id database id of the wst
     * @return according WKms.
     */
    // TODO we also need to know the HYK-id to specify which set we are
    //      inspecting.
    public static List<Zone> getZonesUncached(int riverId, double km) {

        if (logger.isDebugEnabled()) {
            logger.debug("HYKFactory.getZoneUncached " + riverId + " km " + km);
        }

        Session session = SessionHolder.HOLDER.get();

        // TODO respect interval better. respect multiples (sort, limit),
        // TODO respect flow direction of river.
        Query query = session.createQuery(
            "from HYKFormation where entry.HYK.river.id = :riverid " +
            " and entry.km between " +
                ":km - cast(distance_vl/1000.0 - 0.001 as big_decimal) and " +
                ":km + cast(distance_vl/1000.0 + 0.001 as big_decimal)");
        query.setParameter("riverid", riverId);
        query.setParameter("km", new BigDecimal(km));
        logger.debug("Big km " + new BigDecimal(km));
        List<HYKFormation> forms = query.list();

        List<Zone> zones = new ArrayList<Zone>();
        for (HYKFormation form : forms) {
            logger.debug("One HYKFormation found (entry: "
                + form.getEntry().getId()
                + ") /km " + form.getEntry().getKm() + ".");

            // Create respective zones.
            for (HYKFlowZone flowZone: form.getZones()) {
                Zone z = new Zone(flowZone.getA().doubleValue(),
                    flowZone.getB().doubleValue(),
                    flowZone.getType().getName());
                zones.add(z);
            }
        }

        return zones;
    }

    /** Labelled section. */
    public static class Zone {
        /** Lower end of segment. */
        protected double  from;
        /** Upper end of segment. */
        protected double  to;
        /** The label. */
        protected String name;

        /** Constructor for labelled section. */
        public Zone (double from, double to, String name) {
            this.from = from;
            this.to   = to;
            this.name = name;
        }

        /** Get upper value. */
        public double getTo() {
            return to;
        }

        /** Get lower value. */
        public double getFrom() {
            return from;
        }

        /** Get name (type). */
        public String getName() {
            return name;
        }
    } // public static class Zone
}
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