/*
* jQuery css bezier animation support -- Jonah Fox
* version 0.0.1
* Released under the MIT license.
*/
(function ($) {

  $.path = {}


  var V = {
    rotate: function (p, degrees) {
      var radians = degrees * 3.141592654 / 180
      var c = Math.cos(radians), s = Math.sin(radians)
      return [c * p[0] - s * p[1], s * p[0] + c * p[1]]
    },
    scale: function (p, n) {
      return [n * p[0], n * p[1]]
    },
    add: function (a, b) {
      return [a[0] + b[0], a[1] + b[1]]
    },
    minus: function (a, b) {
      return [a[0] - b[0], a[1] - b[1]]
    }
  }

  $.path.bezier = function (params) {
    params.start = $.extend({ angle: 0, length: 0.3333 }, params.start)
    params.end = $.extend({ angle: 0, length: 0.3333 }, params.end)

    this.p1 = [params.start.x, params.start.y];
    this.p4 = [params.end.x, params.end.y];

    var v14 = V.minus(this.p4, this.p1)
    var v12 = V.scale(v14, params.start.length)
    v12 = V.rotate(v12, params.start.angle)
    this.p2 = V.add(this.p1, v12)

    var v41 = V.scale(v14, -1)
    var v43 = V.scale(v41, params.end.length)
    v43 = V.rotate(v43, params.end.angle)
    this.p3 = V.add(this.p4, v43)

    this.f1 = function (t) { return (t * t * t); }
    this.f2 = function (t) { return (3 * t * t * (1 - t)); }
    this.f3 = function (t) { return (3 * t * (1 - t) * (1 - t)); }
    this.f4 = function (t) { return ((1 - t) * (1 - t) * (1 - t)); }

    /* p from 0 to 1 */
    this.css = function (p) {
      var f1 = this.f1(p), f2 = this.f2(p), f3 = this.f3(p), f4 = this.f4(p)
      var x = this.p1[0] * f1 + this.p2[0] * f2 + this.p3[0] * f3 + this.p4[0] * f4;
      var y = this.p1[1] * f1 + this.p2[1] * f2 + this.p3[1] * f3 + this.p4[1] * f4;
      return { top: y + "px", left: x + "px" }
    }
  }

  $.path.arc = function (params) {
    for (var i in params)
      this[i] = params[i]

    this.dir = this.dir || 1

    while (this.start > this.end && this.dir > 0)
      this.start -= 360

    while (this.start < this.end && this.dir < 0)
      this.start += 360


    this.css = function (p) {
      var a = this.start * (p) + this.end * (1 - (p))
      a = a * 3.1415927 / 180 // to radians

      var x = Math.sin(a) * this.radius + this.center[0]
      var y = Math.cos(a) * this.radius + this.center[1]
      return { top: y + "px", left: x + "px" }
    }

  };


  $.fx.step.path = function (fx) {
    var css = fx.end.css(1 - fx.pos)
    for (var i in css)
      fx.elem.style[i] = css[i];
  }
})(jQuery);