/* 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.sinfo.flowdepth;

import java.util.Collection;

import org.apache.commons.lang.math.DoubleRange;
import org.dive4elements.artifacts.CallContext;
import org.dive4elements.river.artifacts.BedHeightsArtifact;
import org.dive4elements.river.artifacts.model.Calculation;
import org.dive4elements.river.artifacts.model.CalculationResult;
import org.dive4elements.river.artifacts.model.WKms;
import org.dive4elements.river.artifacts.resources.Resources;
import org.dive4elements.river.artifacts.sinfo.SINFOArtifact;
import org.dive4elements.river.artifacts.sinfo.common.RiverInfoProvider;
import org.dive4elements.river.artifacts.sinfo.flowdepth.FlowDepthAccess.DifferencesPair;
import org.dive4elements.river.artifacts.sinfo.tkhcalculation.DischargeValuesFinder;
import org.dive4elements.river.artifacts.sinfo.tkhcalculation.TkhCalculator;
import org.dive4elements.river.artifacts.sinfo.tkhstate.BedHeightsFinder;
import org.dive4elements.river.artifacts.sinfo.util.CalculationUtils;
import org.dive4elements.river.artifacts.sinfo.util.RiverInfo;
import org.dive4elements.river.artifacts.sinfo.util.WstInfo;
import org.dive4elements.river.artifacts.states.WaterlevelData;
import org.dive4elements.river.artifacts.states.WaterlevelFetcher;
import org.dive4elements.river.model.River;
import org.dive4elements.river.utils.RiverUtils;

class FlowDepthCalculation {

    // private static Logger log = Logger.getLogger(FlowDepthCalculation.class);

    private final CallContext context;

    public FlowDepthCalculation(final CallContext context) {
        this.context = context;
    }

    public CalculationResult calculate(final SINFOArtifact sinfo) {

        final String user = CalculationUtils.findArtifactUser(this.context, sinfo);

        /* access input data */
        final FlowDepthAccess access = new FlowDepthAccess(sinfo);
        final River river = access.getRiver();
        final RiverInfo riverInfo = new RiverInfo(river);

        final Collection<DifferencesPair> diffPairs = access.getDifferencePairs();

        final DoubleRange calcRange = access.getRange();

        final boolean useTkh = access.isUseTransportBodies();

        /* calculate results for each diff pair */
        final Calculation problems = new Calculation();

        final RiverInfoProvider infoProvider = RiverInfoProvider.forRange(this.context, river, calcRange);

        final String calcModeLabel = Resources.getMsg(this.context.getMeta(), sinfo.getCalculationMode().name());

        final FlowDepthCalculationResults results = new FlowDepthCalculationResults(calcModeLabel, user, riverInfo, calcRange, useTkh);

        for (final DifferencesPair diffPair : diffPairs) {
            final FlowDepthCalculationResult result = calculateResult(calcRange, diffPair, problems, infoProvider, useTkh);
            if (result != null)
                results.addResult(result);
        }

        return new CalculationResult(results, problems);
    }

    /**
     * Calculates one W-MSH differences pair.
     *
     * @param infoProvider
     */
    private FlowDepthCalculationResult calculateResult(final DoubleRange calcRange, final DifferencesPair diffPair,
            final Calculation problems, final RiverInfoProvider infoProvider, final boolean useTkh) {

        /* access real input data from database */
        final String soundingId = diffPair.getSoundingId();
        final String wstId = diffPair.getWstId();

        final BedHeightsFinder bedHeight = loadBedHeight(soundingId, calcRange);
        if (bedHeight == null) {
            final String message = Resources.format(this.context.getMeta(), "Failed to access sounding with id '{0}'", soundingId);
            problems.addProblem(message);
            return null;
        }

        /* REMARK: fetch ALL wst kms, because we want to determine the original reference gauge */
        final WaterlevelData waterlevel = new WaterlevelFetcher().findWaterlevel(this.context, wstId, Double.NaN, Double.NaN);
        if (waterlevel == null) {
            final String message = Resources.format(this.context.getMeta(), "Failed to access waterlevel with id '{0}'", wstId);
            problems.addProblem(message);
            return null;
        }
        final WKms wstKms = waterlevel.getWkms();

        final String wspLabel = wstKms.getName();
        final String soundingLabel = bedHeight.getInfo().getDescription();
        final String label = String.format("%s - %s", wspLabel, soundingLabel);

        checkYearDifference(label, waterlevel, bedHeight.getInfo().getYear(), problems);
        checkWaterlevelDiscretisation(wstKms, calcRange, problems);
        // TODO: prüfen, ob sohlhöhen die calcRange abdecken/überschneiden

        /* re-determine the reference gauge, in the same way as the WaterlevelArtifact would do it */
        final RiverInfoProvider riverInfoProvider = infoProvider.forWaterlevel(waterlevel);

        final int wspYear = waterlevel.getYear();
        final WstInfo wstInfo = new WstInfo(wspLabel, wspYear, riverInfoProvider.getReferenceGauge());

        final DischargeValuesFinder dischargeProvider = DischargeValuesFinder.fromKms(wstKms);

        final River river = riverInfoProvider.getRiver();
        final TkhCalculator tkhCalculator = TkhCalculator.buildTkhCalculator(useTkh, this.context, problems, label, river, calcRange, dischargeProvider,
                bedHeight);

        final FlowDepthCalculator calculator = new FlowDepthCalculator(riverInfoProvider, wstKms, dischargeProvider, bedHeight, tkhCalculator);
        return calculator.execute(label, wstInfo, calcRange);
    }


    /**
     * Checks the year difference between waterlevels and sounding, and issues a warning if too big.
     *
     * Zeitraum Zeitliche Differenz [a]
     * X ≥ 1998 ± 3
     * 1958 ≤ X < 1998 ± 6
     * 1918 ≤ X < 1958 ± 12
     * X < 1918 ± 25
     */
    private void checkYearDifference(final String label, final WaterlevelData waterlevel, final Integer soundingYear, final Calculation problems) {
        if (soundingYear == null)
            return;

        final int wstYear = waterlevel.getYear();
        if (wstYear < 0)
            return;

        final int maxDifference = getMaxDifferenceYears(soundingYear);

        final int difference = Math.abs(soundingYear - wstYear);
        if (difference > maxDifference) {
            final String message = Resources.getMsg(this.context.getMeta(), "sinfo_calc_flow_depth.warning.year_difference", null, label, wstYear,
                    soundingYear);
            problems.addProblem(message);
        }
    }

    private int getMaxDifferenceYears(final int year) {

        if (year < 1918)
            return 25;

        if (1918 <= year && year < 1958)
            return 12;

        if (1958 <= year && year < 1998)
            return 6;

        /* >= 1998 */
        return 3;
    }

    /* Checks if the discretisation of the waterlevel exceeds 1000m */

    private void checkWaterlevelDiscretisation(final WKms wstKms, final DoubleRange calcRange, final Calculation problems) {

        final int size = wstKms.size();
        for (int i = 0; i < size - 2; i++) {
            final double kmPrev = wstKms.getKm(i);
            final double kmNext = wstKms.getKm(i + 1);

            /* only check if we are within the calculation range */
            if (calcRange.overlapsRange(new DoubleRange(kmPrev, kmNext))) {
                if (Math.abs(kmPrev - kmNext) > 1) {
                    final String label = wstKms.getName();

                    final String message = Resources.getMsg(this.context.getMeta(), "sinfo_calc_flow_depth.warning.waterlevel_discretisation", null, label);
                    problems.addProblem(kmPrev, message);
                }
            }
        }
    }

    private BedHeightsFinder loadBedHeight(final String soundingId, final DoubleRange calcRange) {

        // REMARK: absolutely unbelievable....
        // The way how bed-heights (and other data too) is accessed is different for nearly every calculation-type
        // throughout flys.
        // The knowledge on how to parse the datacage-ids is spread through the complete code-base...

        // We use here the way on how bed-heights are accessed by the BedDifferenceAccess/BedDifferenceCalculation, but
        // this is plain random
        final String[] parts = soundingId.split(";");

        final BedHeightsArtifact artifact = (BedHeightsArtifact) RiverUtils.getArtifact(parts[0], this.context);

        final Integer bedheightId = artifact.getDataAsInteger("height_id");
        if (bedheightId == null) {
            // FIXME: error message!
            return null;
        }

        // REMARK: this only works with type 'single'; unclear on how to distinguish from epoch data (or whatever the
        // other type means)
        // Luckily, the requirement is to only access 'single' data here.
        // final String bedheightType = artifact.getDataAsString("type");

        // REMARK: BedDifferences uses this, but we also need the metadata of the BedHeight
        // REMARK: second absolutely awful thing: BedHeight is a hibernate binding class, accessing the database via
        // hibernate stuff
        // BedHeightFactory uses its own (direct) way of accessing the data, with its own implemented data classes.
        // return BedHeightFactory.getHeight(bedheightType, bedheightId, from, to);

        return BedHeightsFinder.forId(bedheightId, calcRange);
    }
}