package com.ximple.io.dgn7;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.LineString;
import com.vividsolutions.jts.geom.LinearRing;

import java.util.Arrays;
import java.util.LinkedList;

public class ElementFactory {
    static final int DEFAULT_ELMHEAD_LENGTH = 28;
    static final int DEFAULT_DISPHEAD_LENGTH = 8;
    static final int MINIMAL_ELEMLENGTH = 18 * 2;

    static final int MAXINUM_LINESTRING_PTLEN = 100;

    private static ElementFactory elementFactory = new ElementFactory();
    private static GeometryFactory factory = new GeometryFactory();

    public static Element createLineString(LineString linestring) {
        Coordinate[] pts = linestring.getCoordinates();
        LineStringElement element = elementFactory.createLineStringElement(pts);
        element.setRange(linestring.getEnvelopeInternal());
        return element;
    }

    public static Element createShape(LinearRing ring) {
        Coordinate[] pts = ring.getCoordinates();
        int elmsize = MINIMAL_ELEMLENGTH + 2 + pts.length * 8;
        ShapeElement element = new ShapeElement(new byte[elmsize]);
        for (int i = 0; i < pts.length; i++) {
            element.setX(i, pts[i].x);
            element.setY(i, pts[i].y);
        }
        element.setVerticeSize(pts.length);
        element.setType(ElementType.SHAPE.id);
        element.setFollowLength((short) ((elmsize / 2) - 2));
        element.setRange(ring.getEnvelopeInternal());
        element.setLevelIndex(0);
        element.setColorIndex(0);
        element.setWeight(0);
        element.setLineStyle(0);
        return element;
    }

    private LineStringElement createLineStringElement(Coordinate[] pts) {
        int elmsize = MINIMAL_ELEMLENGTH + 2 + pts.length * 8;
        LineStringElement element = new LineStringElement(new byte[elmsize]);
        for (int i = 0; i < pts.length; i++) {
            element.setX(i, pts[i].x);
            element.setY(i, pts[i].y);
        }
        element.setVerticeSize(pts.length);
        element.setType(ElementType.LINESTRING.id);
        element.setFollowLength((short) ((elmsize / 2) - 2));
        element.setLevelIndex(0);
        element.setColorIndex(0);
        element.setWeight(0);
        element.setLineStyle(0);
        return element;
    }

    private ShapeElement createShapeElement(Coordinate[] pts) {
        int elmsize = MINIMAL_ELEMLENGTH + 2 + pts.length * 8;
        ShapeElement element = new ShapeElement(new byte[elmsize]);
        for (int i = 0; i < pts.length; i++) {
            element.setX(i, pts[i].x);
            element.setY(i, pts[i].y);
        }
        element.setVerticeSize(pts.length);
        element.setType(ElementType.SHAPE.id);
        element.setFollowLength((short) ((elmsize / 2) - 2));
        element.setLevelIndex(0);
        element.setColorIndex(0);
        element.setWeight(0);
        element.setLineStyle(0);
        return element;
    }

    public static Element createComplexChain(LineString linestring) {
        LinkedList<LineStringElement> elms = new LinkedList<LineStringElement>();
        Coordinate[] allpts = linestring.getCoordinates();
        int segsize = allpts.length / MAXINUM_LINESTRING_PTLEN;
        int currentpos = 0;
        int totalLength = 0;
        for (int seg = 0; seg < segsize; seg++) {
            Coordinate[] pts = Arrays.copyOfRange(allpts,
                    currentpos, currentpos + MAXINUM_LINESTRING_PTLEN + 1, Coordinate[].class);
            LineStringElement element = elementFactory.createLineStringElement(pts);
            currentpos += MAXINUM_LINESTRING_PTLEN;
            element.setRange(element.toGeometry(factory).getEnvelopeInternal());
            element.setComponentElement(true);
            element.setLevelIndex(0);
            totalLength += element.raw.length;
            elms.add(element);
        }
        int remain = allpts.length % MAXINUM_LINESTRING_PTLEN;
        Coordinate[] pts = Arrays.copyOfRange(allpts,
                currentpos, currentpos + remain, Coordinate[].class);
        LineStringElement element = elementFactory.createLineStringElement(pts);
        element.setRange(element.toGeometry(factory).getEnvelopeInternal());
        element.setComponentElement(true);
        element.setLevelIndex(0);
        elms.add(element);
        totalLength += element.raw.length;

        ComplexChainElement result = new ComplexChainElement(new byte[MINIMAL_ELEMLENGTH + 12]);
        result.addAll(elms);
        result.setRange(linestring.getEnvelopeInternal());
        result.setType(ElementType.COMPLEXCHAIN.id);
        result.setFollowLength((short) (((MINIMAL_ELEMLENGTH + 12) / 2) - 2));
        result.setNumOfElement((short) elms.size());
        totalLength += result.raw.length;
        totalLength -= 19;
        result.setTotalLength((short) totalLength);
        result.setLevelIndex(0);
        result.setColorIndex(0);
        result.setWeight(0);
        result.setLineStyle(0);

        return result;
    }
}