/*
*  Copyright (C) 1998-2023 by Northwoods Software Corporation. All Rights Reserved.
*/

/*
* This is an extension and not part of the main GoJS library.
* 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.
*/

import * as go from '../release/go-module.js';

/**
 * This custom {@link Link} class customizes its {@link Shape} to surround the comment node (the from node).
 * If the Shape is filled, it will obscure the comment itself unless the Link is behind the comment node.
 * Thus the default layer for BalloonLinks is "Background".
 *
 * The "corner" property controls the radius of the curves at the corners of the rectangular area surrounding the comment node,
 * rather than the curve at corners along the route, which is always straight.
 * The default value is 10.
 *
 * If you want to experiment with this extension, try the <a href="../../extensionsJSM/BalloonLink.html">Balloon Links</a> sample.
 * @category Part Extension
 */
export class BalloonLink extends go.Link {
  private _base: number = 15;

  /**
   * Constructs a BalloonLink and sets the {@link Part#layerName} property to "Background".
   */
  constructor() {
    super();
    this.layerName = 'Background';
    this.corner = 10;
    this.defaultToPoint = new go.Point(0, 0);
  }

  /**
   * Copies properties to a cloned BalloonLink.
   */
  protected override cloneProtected(copy: this): void {
    super.cloneProtected(copy);
    copy._base = this._base;
  }

  /**
   * Gets or sets width of the base of the triangle at the center point of the {@link Link#fromNode}.
   *
   * The default value is 15.
   */
  get base(): number { return this._base; }
  set base(value: number) { this._base = value; }

  /**
   * Produce a Geometry from the Link's route that draws a "balloon" shape around the {@link Link#fromNode}
   * and has a triangular shape with the base at the fromNode and the top at the toNode.
   */
  public override makeGeometry(): go.Geometry {
    if (this.fromNode === null) return new go.Geometry();
    // assume the fromNode is the comment and the toNode is the commented-upon node
    const bb = this.fromNode.actualBounds.copy().addMargin(<go.Margin>this.fromNode.margin);

    let pn = this.pointsCount === 0 ? bb.center : this.getPoint(this.pointsCount - 1);
    if (this.toNode !== null && bb.intersectsRect(this.toNode.actualBounds)) {
      pn = this.toNode.actualBounds.center;
    } else if (this.toNode === null && this.pointsCount === 0) {
      pn = new go.Point(bb.centerX, bb.bottom + 50);
    }

    const base = Math.max(0, this.base);
    const corner = Math.min(Math.max(0, this.corner), Math.min(bb.width/2, bb.height/2));
    const cornerext = Math.min(base, corner + base/2);

    const fig = new go.PathFigure();
    let prevx = 0;
    let prevy = 0;

    // helper functions
    function start(x: number, y: number) {
      fig.startX = prevx = x;
      fig.startY = prevy = y;
    }
    function point(x: number, y: number, v: number, w: number) {
      fig.add(new go.PathSegment(go.PathSegment.Line, x, y));
      fig.add(new go.PathSegment(go.PathSegment.Line, v, w));
      prevx = v;
      prevy = w;
    }
    function turn(x: number, y: number) {
      if (prevx === x && prevy > y) {  // top left
        fig.add(new go.PathSegment(go.PathSegment.Line, x, y + corner));
        fig.add(new go.PathSegment(go.PathSegment.Arc, 180, 90, x+corner, y+corner, corner, corner));
      } else if (prevx < x && prevy === y) {  // top right
        fig.add(new go.PathSegment(go.PathSegment.Line, x - corner, y));
        fig.add(new go.PathSegment(go.PathSegment.Arc, 270, 90, x-corner, y+corner, corner, corner));
      } else if (prevx === x && prevy < y) {  // bottom right
        fig.add(new go.PathSegment(go.PathSegment.Line, x, y - corner));
        fig.add(new go.PathSegment(go.PathSegment.Arc, 0, 90, x-corner, y-corner, corner, corner));
      } else if (prevx > x && prevy === y) {  // bottom left
        fig.add(new go.PathSegment(go.PathSegment.Line, x + corner, y));
        fig.add(new go.PathSegment(go.PathSegment.Arc, 90, 90, x+corner, y-corner, corner, corner));
      } // else if prevx === x && prevy === y, no-op
      prevx = x;
      prevy = y;
    }

    if (pn.x < bb.left) {
      if (pn.y < bb.top) {
        start(bb.left, Math.min(bb.top + cornerext, bb.bottom - corner));
        point(pn.x, pn.y, Math.min(bb.left + cornerext, bb.right - corner), bb.top);
        turn(bb.right, bb.top); turn(bb.right, bb.bottom); turn(bb.left, bb.bottom);
      } else if (pn.y > bb.bottom) {
        start(Math.min(bb.left + cornerext, bb.right - corner), bb.bottom);
        point(pn.x, pn.y, bb.left, Math.max(bb.bottom - cornerext, bb.top + corner));
        turn(bb.left, bb.top); turn(bb.right, bb.top); turn(bb.right, bb.bottom);
      } else {  // pn.y >= bb.top && pn.y <= bb.bottom
        const y = Math.min(Math.max(pn.y + base/3, bb.top + corner + base), bb.bottom - corner);
        start(bb.left, y);
        point(pn.x, pn.y, bb.left, Math.max(y-base, bb.top + corner));
        turn(bb.left, bb.top); turn(bb.right, bb.top); turn(bb.right, bb.bottom); turn(bb.left, bb.bottom);
      }
    } else if (pn.x > bb.right) {
      if (pn.y < bb.top) {
        start(Math.max(bb.right - cornerext, bb.left + corner), bb.top);
        point(pn.x, pn.y, bb.right, Math.min(bb.top + cornerext, bb.bottom - corner));
        turn(bb.right, bb.bottom); turn(bb.left, bb.bottom); turn(bb.left, bb.top);
      } else if (pn.y > bb.bottom) {
        start(bb.right, Math.max(bb.bottom - cornerext, bb.top + corner));
        point(pn.x, pn.y, Math.max(bb.right - cornerext, bb.left + corner), bb.bottom);
        turn(bb.left, bb.bottom); turn(bb.left, bb.top); turn(bb.right, bb.top);
      } else {  // pn.y >= bb.top && pn.y <= bb.bottom
        const y = Math.min(Math.max(pn.y + base/3, bb.top + corner + base), bb.bottom - corner);
        start(bb.right, Math.max(y-base, bb.top + corner));
        point(pn.x, pn.y, bb.right, y);
        turn(bb.right, bb.bottom); turn(bb.left, bb.bottom); turn(bb.left, bb.top); turn(bb.right, bb.top);
      }
    } else {  // pn.x >= bb.left && pn.x <= bb.right
      const x = Math.min(Math.max(pn.x + base/3, bb.left + corner + base), bb.right - corner);
      if (pn.y < bb.top) {
        start(Math.max(x-base, bb.left + corner), bb.top);
        point(pn.x, pn.y, x, bb.top);
        turn(bb.right, bb.top); turn(bb.right, bb.bottom); turn(bb.left, bb.bottom); turn(bb.left, bb.top);
      } else if (pn.y > bb.bottom) {
        start(x, bb.bottom);
        point(pn.x, pn.y, Math.max(x-base, bb.left + corner), bb.bottom);
        turn(bb.left, bb.bottom); turn(bb.left, bb.top); turn(bb.right, bb.top); turn(bb.right, bb.bottom);
      } else { // inside
        start(bb.left, bb.top+bb.height/2);
        // no "point", just corners
        turn(bb.left, bb.top); turn(bb.right, bb.top); turn(bb.right, bb.bottom); turn(bb.left, bb.bottom);
      }
    }

    const geo = new go.Geometry();
    (<go.PathSegment>fig.segments.last()).close();
    geo.add(fig);
    geo.offset(-this.routeBounds.x, -this.routeBounds.y);
    return geo;
  }
}