import { orient2d } from 'robust-predicates';

function pointInPolygon(p, polygon) {
    var i;
    var ii;
    var k = 0;
    var f;
    var u1;
    var v1;
    var u2;
    var v2;
    var currentP;
    var nextP;

    var x = p[0];
    var y = p[1];

    var numContours = polygon.length;
    for (i = 0; i < numContours; i++) {
        ii = 0;
        var contour = polygon[i];
        var contourLen = contour.length - 1;

        currentP = contour[0];
        if (currentP[0] !== contour[contourLen][0] &&
            currentP[1] !== contour[contourLen][1]) {
            throw new Error('First and last coordinates in a ring must be the same')
        }

        u1 = currentP[0] - x;
        v1 = currentP[1] - y;

        for (ii; ii < contourLen; ii++) {
            nextP = contour[ii + 1];

            u2 = nextP[0] - x;
            v2 = nextP[1] - y;

            if (v1 === 0 && v2 === 0) {
                if ((u2 <= 0 && u1 >= 0) || (u1 <= 0 && u2 >= 0)) { return 0 }
            } else if ((v2 >= 0 && v1 <= 0) || (v2 <= 0 && v1 >= 0)) {
                f = orient2d(u1, u2, v1, v2, 0, 0);
                if (f === 0) { return 0 }
                if ((f > 0 && v2 > 0 && v1 <= 0) || (f < 0 && v2 <= 0 && v1 > 0)) { k++; }
            }
            currentP = nextP;
            v1 = v2;
            u1 = u2;
        }
    }

    if (k % 2 === 0) { return false }
    return true
}

export { pointInPolygon as default };