package org.simantics.district.network.ui.nodes;

import java.awt.geom.AffineTransform;
import java.awt.geom.Path2D;
import java.awt.geom.PathIterator;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;

import org.simantics.district.network.ModelledCRS;
import org.simantics.maps.MapScalingTransform;
import org.simantics.scenegraph.utils.GeometryUtils;

import gnu.trove.list.array.TDoubleArrayList;

public class DistrictNetworkNodeUtils {

    public static ThreadLocal<AffineTransform> sharedTransform = new ThreadLocal<AffineTransform>() {
        protected AffineTransform initialValue() {
            return new AffineTransform();
        }
    };

    public static Rectangle2D calculateDrawnGeometry(Point2D p, Rectangle2D margin, Rectangle2D result, double scaleRecip) {
        if (result == null)
            result = new Rectangle2D.Double();
        double mw = margin.getWidth();
        double mh = margin.getHeight();
        result.setFrame(p.getX() - (mw / 2 * scaleRecip), p.getY() - (mh / 2 * scaleRecip), mw * scaleRecip, mh * scaleRecip);
        return result;
    }

    public static Point2D calculatePoint2D(Point2D point, Point2D result) {
        double x = ModelledCRS.longitudeToX(point.getX());
        double y = ModelledCRS.latitudeToY(-point.getY()); // Inverse because Simantics Diagram is inverted
        if (result == null)
            result = new Point2D.Double(x, y);
        else
            result.setLocation(x, y);
        return result;
    }

    public static AffineTransform getTransformToRectangle(Rectangle2D toDraw, AffineTransform transform) {
        if (transform == null)
            transform = new AffineTransform();

        transform.setTransform(toDraw.getWidth(), 0.0, 0.0, toDraw.getHeight(), toDraw.getCenterX(), toDraw.getCenterY());
        return transform;
    }

    public static double calculateScaleRecip(AffineTransform tr) {
        int zoomLevel = MapScalingTransform.zoomLevel(tr);
        return 1.0 / (getScale(tr) * Math.sqrt(zoomLevel));
    }

    static double getScale(AffineTransform tr) {
        double scale;
        scale = GeometryUtils.getScale(tr);
        scale = Math.max(4096, scale); //Math.min(scale, 32768));
        return scale;
    }

    /**
     * Finds the longest line segment from the provided <code>path</code> and sets
     * <code>centerPoint</code> to the middle of that line and
     * <code>direction</code> as the normalized direction vector of that line
     * segment.
     * 
     * <p>
     * If the path has no points, both <code>centerPoint</code> and
     * <code>direction</code> are set to ({@link Double#NaN}, {@link Double#NaN}).
     * If the path has only one point then <code>centerPoint</code> is set to that
     * single point and <code>direction</code> is set to <code>(1,0)</code>.
     * 
     * @param path the path to process
     * @param centerPoint point for writing the output center point
     * @param direction point for writing the output direction vector
     * @return the amount of points in the path
     */
    public static int calculateCenterPointAndDirection(Path2D path, Point2D centerPoint, Point2D direction) {
        PathIterator pi = path.getPathIterator(null);
        TDoubleArrayList segments = new TDoubleArrayList(20);
        double[] tmp = new double[6];
        while (!pi.isDone()) {
            pi.currentSegment(tmp);
            segments.add(tmp[0]);
            segments.add(tmp[1]);
            pi.next();
        }

        // Cover corner cases
        int segCount = segments.size();
        if (segCount == 0) {
            centerPoint.setLocation(Double.NaN, Double.NaN);
            direction.setLocation(Double.NaN, Double.NaN);
            return 0;
        } else if (segCount == 2) {
            centerPoint.setLocation(segments.getQuick(0), segments.getQuick(1));
            direction.setLocation(1, 0);
            return 1;
        }

        int longest = 1;
        double distance = 0.0;
        for (int i = 2; i < segCount; i += 2) {
            double dx = segments.getQuick(i) - segments.getQuick(i-2);
            double dy = segments.getQuick(i+1) - segments.getQuick(i-1);

            double d = dx * dx + dy * dy;
            if (d > distance) {
                distance = d;
                longest = i;
            }
        }

        double x0 = segments.getQuick(longest - 2);
        double y0 = segments.getQuick(longest - 1);
        double x1 = segments.getQuick(longest);
        double y1 = segments.getQuick(longest + 1);

        distance = Math.sqrt(distance);
        centerPoint.setLocation((x0 + x1) / 2, (y0 + y1) / 2);
        direction.setLocation((x1 - x0) / distance, (y1 - y0) / distance);
        return segCount / 2;
    }

}