package de.intevation.gnv.utils;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Point;
import com.vividsolutions.jts.geom.LineString;
import com.vividsolutions.jts.io.ParseException;
import com.vividsolutions.jts.io.WKTReader;

import de.intevation.gnv.geobackend.base.DefaultResult;
import de.intevation.gnv.geobackend.base.DefaultResultDescriptor;
import de.intevation.gnv.geobackend.base.Result;
import de.intevation.gnv.geobackend.base.ResultDescriptor;
import de.intevation.gnv.geobackend.base.query.QueryExecutor;
import de.intevation.gnv.geobackend.base.query.QueryExecutorFactory;
import de.intevation.gnv.geobackend.base.query.exception.QueryException;
import de.intevation.gnv.math.Interpolation2D;
import de.intevation.gnv.math.LinearFunction;
import de.intevation.gnv.math.LinearMetrics;
import de.intevation.gnv.math.Point2d;
import de.intevation.gnv.state.InputData;

import java.util.Arrays;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;

import org.apache.commons.math.optimization.OptimizationException;
import org.apache.commons.math.optimization.fitting.CurveFitter;
import org.apache.commons.math.optimization.general.GaussNewtonOptimizer;
import org.apache.commons.math.FunctionEvaluationException;

import org.apache.log4j.Logger;

public abstract class WKTUtils {

    private static Logger log = Logger.getLogger(WKTUtils.class);

    private static final String [] DIFF_COLUMS = {
        "GROUP1",
        "GROUP2",
        "GROUP3"
    };

    private static final String [] COLUMN_BLACKLIST = {
        "MEDIAN.MESHPOINT.JPOSITION",
        "MEDIAN.MESHPOINT.IPOSITION"
    };

    public static final double NAUTICAL_MILE = 1852.216d;
    public static final double KILOMETER     = 1000d;

    public static final double EPSILON = 1e-5d;
    public static final int    INTERPOLATION_STEPS =
        Integer.getInteger("interpolation.steps", 500).intValue();


    public static final class SectionHandler
    implements                Interpolation2D.Consumer
    {
        private ArrayList<Point2d> points;
        private List<Coordinate>   path;
        private Collection<Result> output;
        private Result             prototyp;
        private ResultDescriptor   descriptor;
        private boolean            lastWasSuccess;

        public SectionHandler() {
        }

        public SectionHandler(
            List<Coordinate>   path,
            Collection<Result> output,
            ResultDescriptor   descriptor
        ) {
            this.path       = path;
            this.output     = output;
            this.descriptor = descriptor;
            points          = new ArrayList<Point2d>();
            lastWasSuccess  = true;
        }

        public void finish() {
            if (!points.isEmpty()) {
                double distance = toKM(
                    DistanceCalculator.calculateDistance(path));

                if (distance > EPSILON) {

                    Interpolation2D.interpolate(
                        path,
                        points,
                        0d,
                        distance,
                        INTERPOLATION_STEPS,
                        LinearMetrics.INSTANCE,
                        this);
                }

                points.clear();
            }
            lastWasSuccess = true;
        }

        public void setPrototyp(Result prototyp) {
            this.prototyp = prototyp;
        }

        public void handle(Result result) {
            Coordinate coordinate = 
                toCoordinate(result.getString("SHAPE"));
            double value = result.getDouble("YORDINATE");
            int iPos     = result.getInteger("MEDIAN.MESHPOINT.JPOSITION");
            int jPos     = result.getInteger("MEDIAN.MESHPOINT.JPOSITION");
            Point2d p = new Point2d(
                coordinate.x,
                coordinate.y,
                value,
                iPos, jPos);
            points.add(p);
        }

        public void interpolated(Coordinate coordinate, boolean success) {
            DefaultResult result = new DefaultResult(descriptor);
            ResultDescriptor pd = prototyp.getResultDescriptor();

            int pcolums = pd.getColumnCount();
            for (int i = 0, j = 0; i < pcolums; ++i) {
                String colname = pd.getColumnName(i);
                if (blacklisted(colname)) {
                    continue;
                }
                if (colname.equals("SHAPE")) {
                    result.addColumnValue(j, OutputUtils.toWKT(coordinate));
                }
                else if (colname.equals("YORDINATE")) {
                    if (success) {
                        result.addColumnValue(j, Double.valueOf(coordinate.z));
                    }
                    else if (lastWasSuccess) {
                        // only insert null if last was valid.
                        // This prevents flooding the result set with nulls
                        // if interpolating over a large gap.
                        result.addColumnValue(j, null);
                    }
                }
                else {
                    result.addColumnValue(j, prototyp.getObject(i));
                }
                ++j;
            }
            output.add(result);
            lastWasSuccess = success;
        }
    }


    private static final boolean blacklisted(String column) {
        for (int i = 0; i < COLUMN_BLACKLIST.length; ++i) {
            if (COLUMN_BLACKLIST.equals(column)) {
                return true;
            }
        }
        return false;
    }

    private static boolean different(Result a, Result b, int [] indices) {
        for (int i = 0; i < indices.length; ++i) {
            String oa = a.getString(indices[i]);
            String ob = b.getString(indices[i]);

            if (oa == null && ob == null)  {
                continue;
            }

            if (oa == null || ob == null) {
                return true;
            }

            if (!oa.equals(ob)) {
                if (log.isDebugEnabled()) {
                    log.debug("+++++++++++++++ differs ++++++++++++++");
                    log.debug("   " + oa + " != " + ob);
                }
                return true;
            }
        }
        return false;
    }

    public static Collection<Result> process(
        List<Coordinate>   path,
        Collection<Result> input
    ) {
        log.debug("------  number of points before processing: " + input.size());
        ArrayList<Result> output = new ArrayList<Result>();

        Result last = null;

        int [] diffColums = null;

        SectionHandler sectionHandler = null;

        for (Result result: input) {

            if (sectionHandler == null) {

                ResultDescriptor rd = result.getResultDescriptor();
                diffColums = rd.getColumnIndices(DIFF_COLUMS);
                int columns = rd.getColumnCount();

                DefaultResultDescriptor resultDescriptor =
                    new DefaultResultDescriptor();

                for (int j = 0; j < columns; ++j) {
                    String columnName = rd.getColumnName(j);
                    if (!blacklisted(columnName)) {
                        resultDescriptor.addColumn(
                            columnName,
                            rd.getColumnClassName(j));
                    }
                }

                sectionHandler = new SectionHandler(
                    path,
                    output,
                    resultDescriptor);

                sectionHandler.setPrototyp(result);
            }

            if (last != null && different(last, result, diffColums)) {
                sectionHandler.finish();
                sectionHandler.setPrototyp(result);
            }

            sectionHandler.handle(result);

            last = result;
        }

        if (sectionHandler != null) {
            sectionHandler.finish();
        }

        log.debug("------  number of points after processing: " + output.size());

        return output;
    }


    public static Coordinate toCoordinate(String shape) {
        try {
            return ((Point)(new WKTReader().read(shape))).getCoordinate();
        }
        catch (ParseException pe) {
            log.error(pe);
        }
        return null;
    }


    public static final double toKM(double distance) {
        return (distance * NAUTICAL_MILE) / KILOMETER;
    }


    public static String toWKT(Coordinate coordinate) {
        StringBuilder sb = new StringBuilder("POINT(");
        sb.append(coordinate.x)
          .append(' ')
          .append(coordinate.y)
          .append(')');
        return sb.toString();
    }


    public static Collection<Result> worldCoordinatesToIndex(
        Collection<Result>     result,
        Map<String, InputData> inputData,
        String                 ijkQueryID,
        String                 queryID,
        String[]               filterValues
    ) throws ParseException, QueryException
    {
        // 1. IJK Anfragen für Stuetzpunkte im Netz ausführen.
        LineString ls = (LineString)new WKTReader().read(
            inputData.get("mesh_linestring").getValue());

        Coordinate[] coords = ls.getCoordinates();

        List<java.awt.Point> points = new ArrayList<java.awt.Point>(coords.length);

        String meshid = inputData.get("meshid").getValue();
        QueryExecutor queryExecutor = QueryExecutorFactory
                                        .getInstance()
                                        .getQueryExecutor();

        ArrayList missingPoints = new ArrayList();

        String additionWhere = "FEATUREID=FEATUREID";

        for (int i = 0; i < coords.length; i++) {

            String wkt = toWKT(coords[i]);

            result = queryExecutor.executeQuery(ijkQueryID,
                                               new String[]{meshid,wkt});
            if (!result.isEmpty()){
                Result resultValue = result.iterator().next();
                int iPos = resultValue.getInteger(1);
                int jPos = resultValue.getInteger(0);
                log.debug("Found Pos "+iPos+"/"+jPos +" for "+wkt);
                points.add(i, new java.awt.Point(iPos,jPos));
            }else{
                log.debug("No i/j Pos found for "+wkt);
                missingPoints.add(new Object [] { Integer.valueOf(i), coords[i] });
                points.add(i, null);
                // Special Case no i,j found for Coordinate
            }
        }

        if (missingPoints.size() == coords.length) {
            log.debug("cannot create index buffer");
        }
        else { // generate index filter
            boolean remainsMissingPoints = !missingPoints.isEmpty();

            if (remainsMissingPoints) {
                // try to guess the missing (i, j)
                CurveFitter iFitter = new CurveFitter(new GaussNewtonOptimizer(true));
                CurveFitter jFitter = new CurveFitter(new GaussNewtonOptimizer(true));

                for (int i = 0, N = points.size(); i < N; ++i) {
                    java.awt.Point p = (java.awt.Point)points.get(i);
                    if (p != null) {
                        Coordinate coord = coords[i];
                        iFitter.addObservedPoint(coord.x, p.x);
                        jFitter.addObservedPoint(coord.y, p.y);
                    }
                }
                try {
                    // XXX: Assumption: (i, j) are created by componentwise linear function.
                    // This is surely not correct because (x, y) are in a ellipsoid projection.
                    // TODO: use ellipsoid functions and fit with Levenberg Marquardt.
                    double [] iParams = iFitter.fit(
                        LinearFunction.INSTANCE, new double [] { 1d, 1d });

                    double [] jParams = jFitter.fit(
                        LinearFunction.INSTANCE, new double [] { 1d, 1d });

                    for (int i = missingPoints.size()-1; i >= 0; --i) {
                        Object [] a = (Object [])missingPoints.get(i);
                        Coordinate coord = (Coordinate)a[1];
                        int pi = (int)Math.round(iParams[0]*coord.x + iParams[1]);
                        int pj = (int)Math.round(jParams[0]*coord.y + jParams[1]);
                        points.set(
                            ((Integer)a[0]).intValue(),
                            new java.awt.Point(pi, pj));
                    }

                    remainsMissingPoints = false; // we filled the gaps
                }
                catch (FunctionEvaluationException fee) {
                    log.error(fee);
                }
                catch (OptimizationException oe) {
                    log.error(oe);
                }
            }

            if (!remainsMissingPoints) {
                // TODO: Make Tablenames and Columns Configurable
                IndexBuffer ib = new IndexBuffer(
                    points, 
                    "MEDIAN.MESHPOINT.IPOSITION", 
                    "MEDIAN.MESHPOINT.JPOSITION" );
                additionWhere = ib.toWhereClause();
                log.debug("Additional Where Clause = "+additionWhere);
                // 2. Aus diesen Stuetzpunkten den Resultset generieren.
            }
        } // if generate index filter

        String[] addedFilterValues = new String[filterValues.length+1];
        System.arraycopy(filterValues, 0, addedFilterValues, 0, filterValues.length);
        addedFilterValues[filterValues.length] = additionWhere;

        result = process(
            Arrays.asList(coords),
            queryExecutor.executeQuery(
                queryID,
                addedFilterValues));

        return result;
    }
}