(function() {

  var degreesToRadians = fabric.util.degreesToRadians;

  fabric.util.object.extend(fabric.Object.prototype, /** @lends fabric.Object.prototype */ {

    /**
     * Object containing coordinates of object's controls
     * @type Object
     * @default
     */
    oCoords: null,

    /**
     * Checks if object intersects with an area formed by 2 points
     * @param {Object} pointTL top-left point of area
     * @param {Object} pointBR bottom-right point of area
     * @return {Boolean} true if object intersects with an area formed by 2 points
     */
    intersectsWithRect: function(pointTL, pointBR) {
      var oCoords = this.oCoords,
          tl = new fabric.Point(oCoords.tl.x, oCoords.tl.y),
          tr = new fabric.Point(oCoords.tr.x, oCoords.tr.y),
          bl = new fabric.Point(oCoords.bl.x, oCoords.bl.y),
          br = new fabric.Point(oCoords.br.x, oCoords.br.y),
          intersection = fabric.Intersection.intersectPolygonRectangle(
            [tl, tr, br, bl],
            pointTL,
            pointBR
          );
      return intersection.status === 'Intersection';
    },

    /**
     * Checks if object intersects with another object
     * @param {Object} other Object to test
     * @return {Boolean} true if object intersects with another object
     */
    intersectsWithObject: function(other) {
      // extracts coords
      function getCoords(oCoords) {
        return {
          tl: new fabric.Point(oCoords.tl.x, oCoords.tl.y),
          tr: new fabric.Point(oCoords.tr.x, oCoords.tr.y),
          bl: new fabric.Point(oCoords.bl.x, oCoords.bl.y),
          br: new fabric.Point(oCoords.br.x, oCoords.br.y)
        };
      }
      var thisCoords = getCoords(this.oCoords),
          otherCoords = getCoords(other.oCoords),
          intersection = fabric.Intersection.intersectPolygonPolygon(
            [thisCoords.tl, thisCoords.tr, thisCoords.br, thisCoords.bl],
            [otherCoords.tl, otherCoords.tr, otherCoords.br, otherCoords.bl]
          );

      return intersection.status === 'Intersection';
    },

    /**
     * Checks if object is fully contained within area of another object
     * @param {Object} other Object to test
     * @return {Boolean} true if object is fully contained within area of another object
     */
    isContainedWithinObject: function(other) {
      var boundingRect = other.getBoundingRect(),
          point1 = new fabric.Point(boundingRect.left, boundingRect.top),
          point2 = new fabric.Point(boundingRect.left + boundingRect.width, boundingRect.top + boundingRect.height);

      return this.isContainedWithinRect(point1, point2);
    },

    /**
     * Checks if object is fully contained within area formed by 2 points
     * @param {Object} pointTL top-left point of area
     * @param {Object} pointBR bottom-right point of area
     * @return {Boolean} true if object is fully contained within area formed by 2 points
     */
    isContainedWithinRect: function(pointTL, pointBR) {
      var boundingRect = this.getBoundingRect();

      return (
        boundingRect.left >= pointTL.x &&
        boundingRect.left + boundingRect.width <= pointBR.x &&
        boundingRect.top >= pointTL.y &&
        boundingRect.top + boundingRect.height <= pointBR.y
      );
    },

    /**
     * Checks if point is inside the object
     * @param {fabric.Point} point Point to check against
     * @return {Boolean} true if point is inside the object
     */
    containsPoint: function(point) {
      var lines = this._getImageLines(this.oCoords),
          xPoints = this._findCrossPoints(point, lines);

      // if xPoints is odd then point is inside the object
      return (xPoints !== 0 && xPoints % 2 === 1);
    },

    /**
     * Method that returns an object with the object edges in it, given the coordinates of the corners
     * @private
     * @param {Object} oCoords Coordinates of the object corners
     */
    _getImageLines: function(oCoords) {
      return {
        topline: {
          o: oCoords.tl,
          d: oCoords.tr
        },
        rightline: {
          o: oCoords.tr,
          d: oCoords.br
        },
        bottomline: {
          o: oCoords.br,
          d: oCoords.bl
        },
        leftline: {
          o: oCoords.bl,
          d: oCoords.tl
        }
      };
    },

    /**
     * Helper method to determine how many cross points are between the 4 object edges
     * and the horizontal line determined by a point on canvas
     * @private
     * @param {fabric.Point} point Point to check
     * @param {Object} oCoords Coordinates of the object being evaluated
     */
    _findCrossPoints: function(point, oCoords) {
      var b1, b2, a1, a2, xi, yi,
          xcount = 0,
          iLine;

      for (var lineKey in oCoords) {
        iLine = oCoords[lineKey];
        // optimisation 1: line below point. no cross
        if ((iLine.o.y < point.y) && (iLine.d.y < point.y)) {
          continue;
        }
        // optimisation 2: line above point. no cross
        if ((iLine.o.y >= point.y) && (iLine.d.y >= point.y)) {
          continue;
        }
        // optimisation 3: vertical line case
        if ((iLine.o.x === iLine.d.x) && (iLine.o.x >= point.x)) {
          xi = iLine.o.x;
          yi = point.y;
        }
        // calculate the intersection point
        else {
          b1 = 0;
          b2 = (iLine.d.y - iLine.o.y) / (iLine.d.x - iLine.o.x);
          a1 = point.y - b1 * point.x;
          a2 = iLine.o.y - b2 * iLine.o.x;

          xi = - (a1 - a2) / (b1 - b2);
          yi = a1 + b1 * xi;
        }
        // dont count xi < point.x cases
        if (xi >= point.x) {
          xcount += 1;
        }
        // optimisation 4: specific for square images
        if (xcount === 2) {
          break;
        }
      }
      return xcount;
    },

    /**
     * Returns width of an object's bounding rectangle
     * @deprecated since 1.0.4
     * @return {Number} width value
     */
    getBoundingRectWidth: function() {
      return this.getBoundingRect().width;
    },

    /**
     * Returns height of an object's bounding rectangle
     * @deprecated since 1.0.4
     * @return {Number} height value
     */
    getBoundingRectHeight: function() {
      return this.getBoundingRect().height;
    },

    /**
     * Returns coordinates of object's bounding rectangle (left, top, width, height)
     * @return {Object} Object with left, top, width, height properties
     */
    getBoundingRect: function() {
      this.oCoords || this.setCoords();

      var xCoords = [this.oCoords.tl.x, this.oCoords.tr.x, this.oCoords.br.x, this.oCoords.bl.x],
          minX = fabric.util.array.min(xCoords),
          maxX = fabric.util.array.max(xCoords),
          width = Math.abs(minX - maxX),

          yCoords = [this.oCoords.tl.y, this.oCoords.tr.y, this.oCoords.br.y, this.oCoords.bl.y],
          minY = fabric.util.array.min(yCoords),
          maxY = fabric.util.array.max(yCoords),
          height = Math.abs(minY - maxY);

      return {
        left: minX,
        top: minY,
        width: width,
        height: height
      };
    },

    /**
     * Returns width of an object
     * @return {Number} width value
     */
    getWidth: function() {
      return this.width * this.scaleX;
    },

    /**
     * Returns height of an object
     * @return {Number} height value
     */
    getHeight: function() {
      return this.height * this.scaleY;
    },

    /**
     * Makes sure the scale is valid and modifies it if necessary
     * @private
     * @param {Number} value
     * @return {Number}
     */
    _constrainScale: function(value) {
      if (Math.abs(value) < this.minScaleLimit) {
        if (value < 0) {
          return -this.minScaleLimit;
        }
        else {
          return this.minScaleLimit;
        }
      }
      return value;
    },

    /**
     * Scales an object (equally by x and y)
     * @param {Number} value Scale factor
     * @return {fabric.Object} thisArg
     * @chainable
     */
    scale: function(value) {
      value = this._constrainScale(value);

      if (value < 0) {
        this.flipX = !this.flipX;
        this.flipY = !this.flipY;
        value *= -1;
      }

      this.scaleX = value;
      this.scaleY = value;
      this.setCoords();
      return this;
    },

    /**
     * Scales an object to a given width, with respect to bounding box (scaling by x/y equally)
     * @param {Number} value New width value
     * @return {fabric.Object} thisArg
     * @chainable
     */
    scaleToWidth: function(value) {
      // adjust to bounding rect factor so that rotated shapes would fit as well
      var boundingRectFactor = this.getBoundingRectWidth() / this.getWidth();
      return this.scale(value / this.width / boundingRectFactor);
    },

    /**
     * Scales an object to a given height, with respect to bounding box (scaling by x/y equally)
     * @param {Number} value New height value
     * @return {fabric.Object} thisArg
     * @chainable
     */
    scaleToHeight: function(value) {
      // adjust to bounding rect factor so that rotated shapes would fit as well
      var boundingRectFactor = this.getBoundingRectHeight() / this.getHeight();
      return this.scale(value / this.height / boundingRectFactor);
    },

    /**
     * Sets corner position coordinates based on current angle, width and height
     * See https://github.com/kangax/fabric.js/wiki/When-to-call-setCoords
     * @return {fabric.Object} thisArg
     * @chainable
     */
    setCoords: function() {
      var strokeWidth = this.strokeWidth,
          theta = degreesToRadians(this.angle),
          vpt = this.getViewportTransform(),
          f = function (p) {
            return fabric.util.transformPoint(p, vpt);
          },
          w = this.width, currentWidth,
          h = this.height, currentHeight,
          capped = this.strokeLineCap === 'round' || this.strokeLineCap === 'square',
          vLine = this.type === 'line' && this.width === 0,
          hLine = this.type === 'line' && this.height === 0,
          sLine = vLine || hLine,
          strokeW = (capped && hLine) || !sLine,
          strokeH = (capped && vLine) || !sLine;

      if (vLine) {
        w = strokeWidth;
      }
      else if (hLine) {
        h = strokeWidth;
      }
      if (strokeW) {
        w += w > 0 ? strokeWidth : -strokeWidth;
      }
      if (strokeH) {
        h += h > 0 ? strokeWidth : -strokeWidth;
      }
      currentWidth = w * this.scaleX + 2 * this.padding;
      currentHeight = h * this.scaleY + 2 * this.padding;

      // If width is negative, make postive. Fixes path selection issue
      if (currentWidth < 0) {
        currentWidth = Math.abs(currentWidth);
      }

      var _hypotenuse = Math.sqrt(
            Math.pow(currentWidth / 2, 2) +
            Math.pow(currentHeight / 2, 2)),

          _angle = Math.atan(
            isFinite(currentHeight / currentWidth)
              ? currentHeight / currentWidth
              : 0),

          // offset added for rotate and scale actions
          offsetX = Math.cos(_angle + theta) * _hypotenuse,
          offsetY = Math.sin(_angle + theta) * _hypotenuse,
          sinTh = Math.sin(theta),
          cosTh = Math.cos(theta),
          coords = this.getCenterPoint(),
          wh = new fabric.Point(currentWidth, currentHeight),
          _tl =   new fabric.Point(coords.x - offsetX, coords.y - offsetY),
          _tr =   new fabric.Point(_tl.x + (wh.x * cosTh),   _tl.y + (wh.x * sinTh)),
          _bl =   new fabric.Point(_tl.x - (wh.y * sinTh),   _tl.y + (wh.y * cosTh)),
          _mt =   new fabric.Point(_tl.x + (wh.x/2 * cosTh), _tl.y + (wh.x/2 * sinTh)),
          tl  = f(_tl),
          tr  = f(_tr),
          br  = f(new fabric.Point(_tr.x - (wh.y * sinTh),   _tr.y + (wh.y * cosTh))),
          bl  = f(_bl),
          ml  = f(new fabric.Point(_tl.x - (wh.y/2 * sinTh), _tl.y + (wh.y/2 * cosTh))),
          mt  = f(_mt),
          mr  = f(new fabric.Point(_tr.x - (wh.y/2 * sinTh), _tr.y + (wh.y/2 * cosTh))),
          mb  = f(new fabric.Point(_bl.x + (wh.x/2 * cosTh), _bl.y + (wh.x/2 * sinTh))),
          mtr = f(new fabric.Point(_mt.x, _mt.y));

      // debugging

      // setTimeout(function() {
      //   canvas.contextTop.fillStyle = 'green';
      //   canvas.contextTop.fillRect(mb.x, mb.y, 3, 3);
      //   canvas.contextTop.fillRect(bl.x, bl.y, 3, 3);
      //   canvas.contextTop.fillRect(br.x, br.y, 3, 3);
      //   canvas.contextTop.fillRect(tl.x, tl.y, 3, 3);
      //   canvas.contextTop.fillRect(tr.x, tr.y, 3, 3);
      //   canvas.contextTop.fillRect(ml.x, ml.y, 3, 3);
      //   canvas.contextTop.fillRect(mr.x, mr.y, 3, 3);
      //   canvas.contextTop.fillRect(mt.x, mt.y, 3, 3);
      // }, 50);

      this.oCoords = {
        // corners
        tl: tl, tr: tr, br: br, bl: bl,
        // middle
        ml: ml, mt: mt, mr: mr, mb: mb,
        // rotating point
        mtr: mtr
      };

      // set coordinates of the draggable boxes in the corners used to scale/rotate the image
      this._setCornerCoords && this._setCornerCoords();

      return this;
    }
  });
})();