"use strict";
/*
*  Copyright (C) 1998-2017 by Northwoods Software Corporation. All Rights Reserved.
*/

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

// A custom Tool for moving a port on a Node

/**
* @constructor
* @extends Tool
* @class
* This tool only works when the Node has a port (any GraphObject) marked with
* a non-null and non-empty portId that is positioned in a Spot Panel,
* and the user holds down the Shift key.
* It works by modifying that port's GraphObject.alignment property.
*/
export class PortShiftingTool extends go.Tool {
  public readonly name: string = "NodeLabelDragging";

  /** @type {GraphObject} */
  public port: go.GraphObject = null;
  /** @type {Spot} */
  private _originalAlignment: go.Spot = 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 "port" in a Spot Panel,
  * as determined by findPort().
  * @this {PortShiftingTool}
  * @return {boolean}
  */
  public canStart(): boolean {
    if (!go.Tool.prototype.canStart.call(this)) return false;
    var 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
    var e = diagram.lastInput;
    if (!e.left || !e.shift) return false;
    if (!this.isBeyondDragSize()) return false;

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

  /**
  * From the GraphObject at the mouse point, search up the visual tree until we get to
  * an object that has the portId property set to a non-empty string, that is in a Spot Panel,
  * and that is not the main element of the panel (typically the first element).
  * @this {PortShiftingTool}
  * @return {GraphObject} This returns null if no such port is at the mouse down point.
  */
  public findPort(): go.GraphObject {
    var diagram = this.diagram;
    var e = diagram.firstInput;
    var elt = diagram.findObjectAt(e.documentPoint, null, null);
    if (elt === null || !(elt.part instanceof go.Node)) return null;

    while (elt !== null && elt.panel !== null) {
      if (elt.panel.type === go.Panel.Spot && elt.panel.findMainElement() !== elt &&
        elt.portId !== null && elt.portId !== "") return elt;
      elt = elt.panel;
    }
    return null;
  };

  /**
  * Start a transaction, call findPort and remember it as the "port" property,
  * and remember the original value for the port's alignment property.
  * @this {PortShiftingTool}
  */
  public doActivate() {
    this.startTransaction("Shifted Label");
    this.port = this.findPort();
    if (this.port !== null) {
      this._originalAlignment = this.port.alignment.copy();
      var main = this.port.panel.findMainElement();
    }
    super.doActivate.call(this);
  }

  /**
  * Stop any ongoing transaction.
  * @this {PortShiftingTool}
  */
  public doDeactivate() {
    super.doDeactivate.call(this);
    this.stopTransaction();
  }

  /**
  * Clear any reference to a port element.
  * @this {PortShiftingTool}
  */
  public doStop() {
    this.port = null;
    super.doStop.call(this);
  }

  /**
  * Restore the port's original value for GraphObject.alignment.
  * @this {PortShiftingTool}
  */
  public doCancel() {
    if (this.port !== null) {
      this.port.alignment = this._originalAlignment;
    }
    super.doCancel.call(this);
  }

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

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

  /**
  * Save the port's GraphObject.alignment as a fractional Spot in the Spot Panel
  * that the port is in.  Thus if the main element changes size, the relative positions
  * of the ports will be maintained.  But that does assume that the port must remain
  * inside the main element -- it cannot wander away from the node.
  * This does not modify the port's GraphObject.alignmentFocus property.
  * @this {PortShiftingTool}
  */
  public updateAlignment() {
    if (this.port === null) return;
    var last = this.diagram.lastInput.documentPoint;
    var main = this.port.panel.findMainElement();
    var tl = main.getDocumentPoint(go.Spot.TopLeft);
    var br = main.getDocumentPoint(go.Spot.BottomRight);
    var x = Math.max(0, Math.min((last.x - tl.x) / (br.x - tl.x), 1));
    var y = Math.max(0, Math.min((last.y - tl.y) / (br.y - tl.y), 1));
    this.port.alignment = new go.Spot(x, y);
  }

}