import math from '../../../math';
import utils from '../../../utils';

/**
 * Builds a line to draw
 *
 * Ignored from docs since it is not directly exposed.
 *
 * @ignore
 * @private
 * @param graphicsData {PIXI.WebGLGraphicsData} The graphics object containing all the necessary properties
 * @param webGLData {object} an object containing all the webGL-specific information to create this shape
 */
const buildLine = function (graphicsData, webGLData)
{
    // TODO OPTIMISE!
    let points = graphicsData.points;

    if (points.length === 0)
    {
        return;
    }
    // if the line width is an odd number add 0.5 to align to a whole pixel
    // commenting this out fixes #711 and #1620
    // if (graphicsData.lineWidth%2)
    // {
    //     for (i = 0; i < points.length; i++)
    //     {
    //         points[i] += 0.5;
    //     }
    // }

    // get first and last point.. figure out the middle!
    const firstPoint = new math.Point(points[0], points[1]);
    let lastPoint = new math.Point(points[points.length - 2], points[points.length - 1]);

    // if the first point is the last point - gonna have issues :)
    if (firstPoint.x === lastPoint.x && firstPoint.y === lastPoint.y)
    {
        // need to clone as we are going to slightly modify the shape..
        points = points.slice();

        points.pop();
        points.pop();

        lastPoint = new math.Point(points[points.length - 2], points[points.length - 1]);

        const midPointX = lastPoint.x + (firstPoint.x - lastPoint.x) *0.5;
        const midPointY = lastPoint.y + (firstPoint.y - lastPoint.y) *0.5;

        points.unshift(midPointX, midPointY);
        points.push(midPointX, midPointY);
    }

    const verts = webGLData.points;
    const indices = webGLData.indices;
    const length = points.length / 2;
    let indexCount = points.length;
    let indexStart = verts.length/6;

    // DRAW the Line
    const width = graphicsData.lineWidth / 2;

    // sort color
    const color = utils.hex2rgb(graphicsData.lineColor);
    const alpha = graphicsData.lineAlpha;
    const r = color[0] * alpha;
    const g = color[1] * alpha;
    const b = color[2] * alpha;

    let px, py, p1x, p1y, p2x, p2y, p3x, p3y;
    let perpx, perpy, perp2x, perp2y, perp3x, perp3y;
    let a1, b1, c1, a2, b2, c2;
    let denom, pdist, dist;

    p1x = points[0];
    p1y = points[1];

    p2x = points[2];
    p2y = points[3];

    perpx = -(p1y - p2y);
    perpy =  p1x - p2x;

    dist = Math.sqrt(perpx*perpx + perpy*perpy);

    perpx /= dist;
    perpy /= dist;
    perpx *= width;
    perpy *= width;

    // start
    verts.push(p1x - perpx , p1y - perpy,
                r, g, b, alpha);

    verts.push(p1x + perpx , p1y + perpy,
                r, g, b, alpha);

    for (let i = 1; i < length-1; i++)
    {
        p1x = points[(i-1)*2];
        p1y = points[(i-1)*2 + 1];

        p2x = points[(i)*2];
        p2y = points[(i)*2 + 1];

        p3x = points[(i+1)*2];
        p3y = points[(i+1)*2 + 1];

        perpx = -(p1y - p2y);
        perpy = p1x - p2x;

        dist = Math.sqrt(perpx*perpx + perpy*perpy);
        perpx /= dist;
        perpy /= dist;
        perpx *= width;
        perpy *= width;

        perp2x = -(p2y - p3y);
        perp2y = p2x - p3x;

        dist = Math.sqrt(perp2x*perp2x + perp2y*perp2y);
        perp2x /= dist;
        perp2y /= dist;
        perp2x *= width;
        perp2y *= width;

        a1 = (-perpy + p1y) - (-perpy + p2y);
        b1 = (-perpx + p2x) - (-perpx + p1x);
        c1 = (-perpx + p1x) * (-perpy + p2y) - (-perpx + p2x) * (-perpy + p1y);
        a2 = (-perp2y + p3y) - (-perp2y + p2y);
        b2 = (-perp2x + p2x) - (-perp2x + p3x);
        c2 = (-perp2x + p3x) * (-perp2y + p2y) - (-perp2x + p2x) * (-perp2y + p3y);

        denom = a1*b2 - a2*b1;

        if (Math.abs(denom) < 0.1 )
        {

            denom+=10.1;
            verts.push(p2x - perpx , p2y - perpy,
                r, g, b, alpha);

            verts.push(p2x + perpx , p2y + perpy,
                r, g, b, alpha);

            continue;
        }

        px = (b1*c2 - b2*c1)/denom;
        py = (a2*c1 - a1*c2)/denom;


        pdist = (px -p2x) * (px -p2x) + (py -p2y) * (py -p2y);


        if (pdist > 140 * 140)
        {
            perp3x = perpx - perp2x;
            perp3y = perpy - perp2y;

            dist = Math.sqrt(perp3x*perp3x + perp3y*perp3y);
            perp3x /= dist;
            perp3y /= dist;
            perp3x *= width;
            perp3y *= width;

            verts.push(p2x - perp3x, p2y -perp3y);
            verts.push(r, g, b, alpha);

            verts.push(p2x + perp3x, p2y +perp3y);
            verts.push(r, g, b, alpha);

            verts.push(p2x - perp3x, p2y -perp3y);
            verts.push(r, g, b, alpha);

            indexCount++;
        }
        else
        {

            verts.push(px , py);
            verts.push(r, g, b, alpha);

            verts.push(p2x - (px-p2x), p2y - (py - p2y));
            verts.push(r, g, b, alpha);
        }
    }

    p1x = points[(length-2)*2];
    p1y = points[(length-2)*2 + 1];

    p2x = points[(length-1)*2];
    p2y = points[(length-1)*2 + 1];

    perpx = -(p1y - p2y);
    perpy = p1x - p2x;

    dist = Math.sqrt(perpx*perpx + perpy*perpy);
    perpx /= dist;
    perpy /= dist;
    perpx *= width;
    perpy *= width;

    verts.push(p2x - perpx , p2y - perpy);
    verts.push(r, g, b, alpha);

    verts.push(p2x + perpx , p2y + perpy);
    verts.push(r, g, b, alpha);

    indices.push(indexStart);

    for (let i = 0; i < indexCount; i++)
    {
        indices.push(indexStart++);
    }

    indices.push(indexStart-1);
};

export default buildLine;