/** A widget to create a new segment */

IriSP.SliceWidget = function(Popcorn, config, Serializer) {

  IriSP.Widget.call(this, Popcorn, config, Serializer);

};

IriSP.SliceWidget.prototype = new IriSP.Widget();

IriSP.SliceWidget.prototype.draw = function() {

  var templ = Mustache.to_html(IriSP.sliceWidget_template);

  this.selector.append(templ);

  this.sliceZone = this.selector.find(".Ldt-sliceZone");

  /* global variables used to keep the position and width

     of the zone.

  */  

  this.zoneLeft = 0;

  this.zoneWidth = 0;

  this.leftHandle = this.selector.find(".Ldt-sliceLeftHandle");

  this.rightHandle = this.selector.find(".Ldt-sliceRightHandle");

  this.leftHandle.draggable({axis: "x",

  drag: IriSP.wrap(this, this.leftHandleDragged),  

  containment: "parent"

  });

  this.rightHandle.draggable({axis: "x",

  drag: IriSP.wrap(this, this.rightHandleDragged),    

  containment: "parent"

  });

  this.leftHandle.css("position", "absolute");

  this.rightHandle.css("position", "absolute");

  this._Popcorn.listen("IriSP.SliceWidget.position", 

                        IriSP.wrap(this, this.positionSliceHandler));

  this._Popcorn.listen("IriSP.SliceWidget.show", IriSP.wrap(this, this.show));

  this._Popcorn.listen("IriSP.SliceWidget.hide", IriSP.wrap(this, this.hide));

  this.selector.hide();

};

/** responds to an "IriSP.SliceWidget.position" message

    @param params an array with the first element being the left distance in

           percents and the second element the width of the slice in pixels

*/        

IriSP.SliceWidget.prototype.positionSliceHandler = function(params) {

  left = params[0];

  width = params[1];

  this.zoneLeft = left;

  this.zoneWidth = width;

  this.sliceZone.css("left", left + "px");

  this.sliceZone.css("width", width + "px");

  this.leftHandle.css("left", (left - 7) + "px");

  this.rightHandle.css("left", left + width + "px");

  this._leftHandleOldLeft = left - 7;

  this._rightHandleOldLeft = left + width;

};

/** handle a dragging of the left handle */

IriSP.SliceWidget.prototype.leftHandleDragged = function(event, ui) {

  /* we have a special variable, this._leftHandleOldLeft, to keep the

     previous position of the handle. We do that to know in what direction

     is the handle being dragged

  */

  var currentX = this.leftHandle.position()["left"];

  var rightHandleX = this.rightHandle.position()["left"];

  if (currentX >= rightHandleX - 7 && ui.position.left >= this._leftHandleOldLeft) {

    /* prevent the handle from moving past the right handle */

    ui.position.left = this._leftHandleOldLeft;

  }

  var increment = this.zoneLeft - (currentX + 7);

  this.zoneWidth += increment;

  this.zoneLeft = currentX + 7;

  this.sliceZone.css("width", this.zoneWidth);

  this.sliceZone.css("left", this.zoneLeft + "px");

  this.broadcastChanges();

  this._leftHandleOldLeft = ui.position.left;  

};

/** handle a dragging of the right handle */

IriSP.SliceWidget.prototype.rightHandleDragged = function(event, ui) { 

  var currentX = this.rightHandle.position()["left"];

  var leftHandleX = this.leftHandle.position()["left"];

  if (currentX <= leftHandleX + 7 && ui.position.left <= this._rightHandleOldLeft) {

    /* prevent the handle from moving past the right handle */

    ui.position.left = this._rightHandleOldLeft;

  }

  var increment = currentX - (this.zoneLeft + this.zoneWidth);  

  this.zoneWidth += increment;  

  this.sliceZone.css("width", this.zoneWidth);

  this.broadcastChanges();

  this._rightHandleOldLeft = ui.position.left; 

};

/** tell to the world that the coordinates of the slice have

    changed 

*/

IriSP.SliceWidget.prototype.broadcastChanges = function() {

  var leftPercent = (this.zoneLeft / this.selector.width()) * 100;

  var zonePercent = (this.zoneWidth / this.selector.width()) * 100;

  this._Popcorn.trigger("IriSP.SliceWidget.zoneChange", [leftPercent, zonePercent]);  

};

IriSP.SliceWidget.prototype.show = function() {

  this.selector.show();

};

IriSP.SliceWidget.prototype.hide = function() {

  this.selector.hide();

};