/*
 *  Copyright 1998-2025 by Northwoods Software Corporation. All Rights Reserved.
 */
/*
 * This is an extension and not part of the main GoJS library.
 * The source code for this is at extensionsJSM/ParallelRouteLink.ts.
 * Note that the API for this class may change with any version, even point releases.
 * If you intend to use an extension in production, you should copy the code to your own source directory.
 * Extensions can be found in the GoJS kit under the extensions or extensionsJSM folders.
 * See the Extensions intro page (https://gojs.net/latest/intro/extensions.html) for more information.
 */

/**
 * This custom {@link go.Link} class customizes its route to go parallel to other links connecting the same ports,
 * if the link is not orthogonal and is not Bezier curved.
 *
 * If you want to experiment with this extension, try the <a href="../../samples/ParallelRoute.html">Parallel Route Links</a> sample.
 * @category Part Extension
 */
class ParallelRouteLink extends go.Link {
    constructor(init) {
        super();
        if (init)
            Object.assign(this, init);
    }
    /**
     * Constructs the link's route by modifying {@link points}.
     * @returns true if it computed a route of points
     */
    computePoints() {
        const result = super.computePoints();
        if (!this.isOrthogonal && this.curve !== go.Curve.Bezier && this.hasCurviness()) {
            const curv = this.computeCurviness();
            if (curv !== 0) {
                const num = this.pointsCount;
                let pidx = 0;
                let qidx = num - 1;
                if (num >= 4) {
                    pidx++;
                    qidx--;
                }
                const frompt = this.getPoint(pidx);
                const topt = this.getPoint(qidx);
                const dx = topt.x - frompt.x;
                const dy = topt.y - frompt.y;
                let mx = frompt.x + (dx * 1) / 8;
                let my = frompt.y + (dy * 1) / 8;
                let px = mx;
                let py = my;
                if (-0.01 < dy && dy < 0.01) {
                    if (dx > 0)
                        py -= curv;
                    else
                        py += curv;
                }
                else {
                    const slope = -dx / dy;
                    let e = Math.sqrt((curv * curv) / (slope * slope + 1));
                    if (curv < 0)
                        e = -e;
                    px = (dy < 0 ? -1 : 1) * e + mx;
                    py = slope * (px - mx) + my;
                }
                mx = frompt.x + (dx * 7) / 8;
                my = frompt.y + (dy * 7) / 8;
                let qx = mx;
                let qy = my;
                if (-0.01 < dy && dy < 0.01) {
                    if (dx > 0)
                        qy -= curv;
                    else
                        qy += curv;
                }
                else {
                    const slope = -dx / dy;
                    let e = Math.sqrt((curv * curv) / (slope * slope + 1));
                    if (curv < 0)
                        e = -e;
                    qx = (dy < 0 ? -1 : 1) * e + mx;
                    qy = slope * (qx - mx) + my;
                }
                this.insertPointAt(pidx + 1, px, py);
                this.insertPointAt(qidx + 1, qx, qy);
            }
        }
        return result;
    }
}