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

import * as go from '../../../release/go';

// A custom Tool for moving a label on a Node
export class NodeLabelDraggingTool extends go.Tool {

  /**
   * @constructor
   * @extends Tool
   * @class
   * This tool only works when the Node has a label (any GraphObject) marked with
   * { _isNodeLabel: true } that is positioned in a Spot Panel.
   * It works by modifying that label's GraphObject.alignment property to have an
   * offset from the center of the panel.
   */

  private label: go.GraphObject | null;
  private _offset: go.Point;
  private _originalAlignment: go.Spot | null;
  private _originalCenter: go.Point | null;

  constructor() {
    super();
    this.name = 'NodeLabelDragging';

    /** @type {GraphObject} */
    this.label = null;
    /** @type {Point} */
    this._offset = new go.Point();  // of the mouse relative to the center of the label object
    /** @type {go.Spot} */
    this._originalAlignment = null;
    /** @type {Point} */
    this._originalCenter = null;
  }

  /**
   * This tool can only start if the mouse has moved enough so that it is not a click,
   * and if the mouse down point is on a GraphObject "label" in a Spot Panel,
   * as determined by findLabel().
   * @this {NodeLabelDraggingTool}
   * @return {boolean}
   */
  public canStart(): boolean {
    if (!go.Tool.prototype.canStart.call(this)) return false;
    const diagram = this.diagram;
    if (diagram === null) return false;
    // require left button & that it has moved far enough away from the mouse down point, so it isn't a click
    const e = diagram.lastInput;
    if (!e.left) return false;
    if (!this.isBeyondDragSize()) return false;

    return this.findLabel() !== null;
  }

  /**
   * From the GraphObject at the mouse point, search up the visual tree until we get to
   * an object that has the "_isNodeLabel" property set to true, that is in a Spot Panel,
   * and that is not the first element of that Panel (i.e. not the main element of the panel).
   * @this {NodeLabelDraggingTool}
   * @return {GraphObject} This returns null if no such label is at the mouse down point.
   */
  public findLabel(): go.GraphObject | null {
    const diagram = this.diagram;
    const e = diagram.firstInput;
    let elt = diagram.findObjectAt(e.documentPoint, null, null);

    if (elt === null || !(elt.part instanceof go.Node)) return null;
    if (elt.part instanceof go.Node) {
      elt.part.isSelected = true;
    }
    while (elt.panel !== null) {
      if ((elt as any)._isNodeLabel && elt.panel.type === go.Panel.Spot && elt.panel.findMainElement() !== elt) return elt;
      elt = elt.panel;
    }

    return null;
  }

  /**
   * Start a transaction, call findLabel and remember it as the "label" property,
   * and remember the original value for the label's alignment property.
   * @this {NodeLabelDraggingTool}
   */
  public doActivate(): void {
    this.startTransaction('Shifted Label');
    this.label = this.findLabel();
    if (this.label !== null) {
      // compute the offset of the mouse-down point relative to the center of the label
      this._offset = this.diagram.firstInput.documentPoint.copy().subtract(this.label.getDocumentPoint(go.Spot.Center));
      this._originalAlignment = this.label.alignment.copy();
      if (this.label !== null && this.label.panel !== null) {
        const main = this.label.panel.findMainElement();
        if (main !== null) {
          this._originalCenter = main.getDocumentPoint(go.Spot.Center);
        }
      }
    }
    go.Tool.prototype.doActivate.call(this);
  }

  /**
   * Stop any ongoing transaction.
   * @this {NodeLabelDraggingTool}
   */
  public doDeactivate(): void {
    go.Tool.prototype.doDeactivate.call(this);
    this.stopTransaction();
  }

  /**
   * Clear any reference to a label element.
   * @this {NodeLabelDraggingTool}
   */
  public doStop(): void {
    this.label = null;
    go.Tool.prototype.doStop.call(this);
  }

  /**
   * Restore the label's original value for GraphObject.alignment.
   * @this {NodeLabelDraggingTool}
   */
  public doCancel(): void {
    if (this.label !== null && this._originalAlignment !== null) {
      // this.label.alignment = this._originalAlignment;
      const node: go.Node = this.label.part as go.Node;
      this.diagram.model.set(node.data, 'labelAlignment', this._originalAlignment);
    }
    go.Tool.prototype.doCancel.call(this);
  }

  /**
   * During the drag, call updateAlignment in order to set the GraphObject.alignment of the label.
   * @this {NodeLabelDraggingTool}
   */
  public doMouseMove(): void {
    if (!this.isActive) return;
    this.updateAlignment();
  }

  /**
   * At the end of the drag, update the alignment of the label and finish the tool,
   * completing a transaction.
   * @this {NodeLabelDraggingTool}
   */
  public doMouseUp(): void {
    if (!this.isActive) return;
    this.updateAlignment();
    this.transactionResult = 'Shifted Label';
    this.stopTool();
  }

  /**
   * Save the label's GraphObject.alignment as an absolute offset from the center of the Spot Panel
   * that the label is in.
   * @this {NodeLabelDraggingTool}
   */
  public updateAlignment(): void {
    if (this.label === null) return;
    const last = this.diagram.lastInput.documentPoint;
    const cntr = this._originalCenter;
    if (cntr !== null) {
      const align: go.Spot = new go.Spot(0.5, 0.5, last.x - this._offset.x - cntr.x, last.y - this._offset.y - cntr.y);
      // this.label.alignment = new go.Spot(0.5, 0.5, last.x - this._offset.x - cntr.x, last.y - this._offset.y - cntr.y);

      const node: go.Node = this.label.part as go.Node;
      this.diagram.model.set(node.data, 'labelAlignment', align);
    }
  }

}

// export = NodeLabelDraggingTool;