/**

 * Copyright (c) 2011-2014 Felix Gnass

 * Licensed under the MIT license

 */

(function(root, factory) {

  /* CommonJS */

  if (typeof exports == 'object')  module.exports = factory()

  /* AMD module */

  else if (typeof define == 'function' && define.amd) define(factory)

  /* Browser global */

  else root.Spinner = factory()

}

(this, function() {

  "use strict";

  var prefixes = ['webkit', 'Moz', 'ms', 'O'] /* Vendor prefixes */

    , animations = {} /* Animation rules keyed by their name */

    , useCssAnimations /* Whether to use CSS animations or setTimeout */

  /**

   * Utility function to create elements. If no tag name is given,

   * a DIV is created. Optionally properties can be passed.

   */

  function createEl(tag, prop) {

    var el = document.createElement(tag || 'div')

      , n

    for(n in prop) el[n] = prop[n]

    return el

  }

  /**

   * Appends children and returns the parent.

   */

  function ins(parent /* child1, child2, ...*/) {

    for (var i=1, n=arguments.length; i<n; i++)

      parent.appendChild(arguments[i])

    return parent

  }

  /**

   * Insert a new stylesheet to hold the @keyframe or VML rules.

   */

  var sheet = (function() {

    var el = createEl('style', {type : 'text/css'})

    ins(document.getElementsByTagName('head')[0], el)

    return el.sheet || el.styleSheet

  }())

  /**

   * Creates an opacity keyframe animation rule and returns its name.

   * Since most mobile Webkits have timing issues with animation-delay,

   * we create separate rules for each line/segment.

   */

  function addAnimation(alpha, trail, i, lines) {

    var name = ['opacity', trail, ~~(alpha*100), i, lines].join('-')

      , start = 0.01 + i/lines * 100

      , z = Math.max(1 - (1-alpha) / trail * (100-start), alpha)

      , prefix = useCssAnimations.substring(0, useCssAnimations.indexOf('Animation')).toLowerCase()

      , pre = prefix && '-' + prefix + '-' || ''

    if (!animations[name]) {

      sheet.insertRule(

        '@' + pre + 'keyframes ' + name + '{' +

        '0%{opacity:' + z + '}' +

        start + '%{opacity:' + alpha + '}' +

        (start+0.01) + '%{opacity:1}' +

        (start+trail) % 100 + '%{opacity:' + alpha + '}' +

        '100%{opacity:' + z + '}' +

        '}', sheet.cssRules.length)

      animations[name] = 1

    }

    return name

  }

  /**

   * Tries various vendor prefixes and returns the first supported property.

   */

  function vendor(el, prop) {

    var s = el.style

      , pp

      , i

    prop = prop.charAt(0).toUpperCase() + prop.slice(1)

    for(i=0; i<prefixes.length; i++) {

      pp = prefixes[i]+prop

      if(s[pp] !== undefined) return pp

    }

    if(s[prop] !== undefined) return prop

  }

  /**

   * Sets multiple style properties at once.

   */

  function css(el, prop) {

    for (var n in prop)

      el.style[vendor(el, n)||n] = prop[n]

    return el

  }

  /**

   * Fills in default values.

   */

  function merge(obj) {

    for (var i=1; i < arguments.length; i++) {

      var def = arguments[i]

      for (var n in def)

        if (obj[n] === undefined) obj[n] = def[n]

    }

    return obj

  }

  /**

   * Returns the absolute page-offset of the given element.

   */

  function pos(el) {

    var o = { x:el.offsetLeft, y:el.offsetTop }

    while((el = el.offsetParent))

      o.x+=el.offsetLeft, o.y+=el.offsetTop

    return o

  }

  /**

   * Returns the line color from the given string or array.

   */

  function getColor(color, idx) {

    return typeof color == 'string' ? color : color[idx % color.length]

  }

  // Built-in defaults

  var defaults = {

    lines: 12,            // The number of lines to draw

    length: 7,            // The length of each line

    width: 5,             // The line thickness

    radius: 10,           // The radius of the inner circle

    rotate: 0,            // Rotation offset

    corners: 1,           // Roundness (0..1)

    color: '#000',        // #rgb or #rrggbb

    direction: 1,         // 1: clockwise, -1: counterclockwise

    speed: 1,             // Rounds per second

    trail: 100,           // Afterglow percentage

    opacity: 1/4,         // Opacity of the lines

    fps: 20,              // Frames per second when using setTimeout()

    zIndex: 2e9,          // Use a high z-index by default

    className: 'spinner', // CSS class to assign to the element

    top: '50%',           // center vertically

    left: '50%',          // center horizontally

    position: 'absolute'  // element position

  }

  /** The constructor */

  function Spinner(o) {

    this.opts = merge(o || {}, Spinner.defaults, defaults)

  }

  // Global defaults that override the built-ins:

  Spinner.defaults = {}

  merge(Spinner.prototype, {

    /**

     * Adds the spinner to the given target element. If this instance is already

     * spinning, it is automatically removed from its previous target b calling

     * stop() internally.

     */

    spin: function(target) {

      this.stop()

      var self = this

        , o = self.opts

        , el = self.el = css(createEl(0, {className: o.className}), {position: o.position, width: 0, zIndex: o.zIndex})

        , mid = o.radius+o.length+o.width

      css(el, {

        left: o.left,

        top: o.top

      })

      if (target) {

        target.insertBefore(el, target.firstChild||null)

      }

      el.setAttribute('role', 'progressbar')

      self.lines(el, self.opts)

      if (!useCssAnimations) {

        // No CSS animation support, use setTimeout() instead

        var i = 0

          , start = (o.lines - 1) * (1 - o.direction) / 2

          , alpha

          , fps = o.fps

          , f = fps/o.speed

          , ostep = (1-o.opacity) / (f*o.trail / 100)

          , astep = f/o.lines

        ;(function anim() {

          i++;

          for (var j = 0; j < o.lines; j++) {

            alpha = Math.max(1 - (i + (o.lines - j) * astep) % f * ostep, o.opacity)

            self.opacity(el, j * o.direction + start, alpha, o)

          }

          self.timeout = self.el && setTimeout(anim, ~~(1000/fps))

        })()

      }

      return self

    },

    /**

     * Stops and removes the Spinner.

     */

    stop: function() {

      var el = this.el

      if (el) {

        clearTimeout(this.timeout)

        if (el.parentNode) el.parentNode.removeChild(el)

        this.el = undefined

      }

      return this

    },

    /**

     * Internal method that draws the individual lines. Will be overwritten

     * in VML fallback mode below.

     */

    lines: function(el, o) {

      var i = 0

        , start = (o.lines - 1) * (1 - o.direction) / 2

        , seg

      function fill(color, shadow) {

        return css(createEl(), {

          position: 'absolute',

          width: (o.length+o.width) + 'px',

          height: o.width + 'px',

          background: color,

          boxShadow: shadow,

          transformOrigin: 'left',

          transform: 'rotate(' + ~~(360/o.lines*i+o.rotate) + 'deg) translate(' + o.radius+'px' +',0)',

          borderRadius: (o.corners * o.width>>1) + 'px'

        })

      }

      for (; i < o.lines; i++) {

        seg = css(createEl(), {

          position: 'absolute',

          top: 1+~(o.width/2) + 'px',

          transform: o.hwaccel ? 'translate3d(0,0,0)' : '',

          opacity: o.opacity,

          animation: useCssAnimations && addAnimation(o.opacity, o.trail, start + i * o.direction, o.lines) + ' ' + 1/o.speed + 's linear infinite'

        })

        if (o.shadow) ins(seg, css(fill('#000', '0 0 4px ' + '#000'), {top: 2+'px'}))

        ins(el, ins(seg, fill(getColor(o.color, i), '0 0 1px rgba(0,0,0,.1)')))

      }

      return el

    },

    /**

     * Internal method that adjusts the opacity of a single line.

     * Will be overwritten in VML fallback mode below.

     */

    opacity: function(el, i, val) {

      if (i < el.childNodes.length) el.childNodes[i].style.opacity = val

    }

  })

  function initVML() {

    /* Utility function to create a VML tag */

    function vml(tag, attr) {

      return createEl('<' + tag + ' xmlns="urn:schemas-microsoft.com:vml" class="spin-vml">', attr)

    }

    // No CSS transforms but VML support, add a CSS rule for VML elements:

    sheet.addRule('.spin-vml', 'behavior:url(#default#VML)')

    Spinner.prototype.lines = function(el, o) {

      var r = o.length+o.width

        , s = 2*r

      function grp() {

        return css(

          vml('group', {

            coordsize: s + ' ' + s,

            coordorigin: -r + ' ' + -r

          }),

          { width: s, height: s }

        )

      }

      var margin = -(o.width+o.length)*2 + 'px'

        , g = css(grp(), {position: 'absolute', top: margin, left: margin})

        , i

      function seg(i, dx, filter) {

        ins(g,

          ins(css(grp(), {rotation: 360 / o.lines * i + 'deg', left: ~~dx}),

            ins(css(vml('roundrect', {arcsize: o.corners}), {

                width: r,

                height: o.width,

                left: o.radius,

                top: -o.width>>1,

                filter: filter

              }),

              vml('fill', {color: getColor(o.color, i), opacity: o.opacity}),

              vml('stroke', {opacity: 0}) // transparent stroke to fix color bleeding upon opacity change

            )

          )

        )

      }

      if (o.shadow)

        for (i = 1; i <= o.lines; i++)

          seg(i, -2, 'progid:DXImageTransform.Microsoft.Blur(pixelradius=2,makeshadow=1,shadowopacity=.3)')

      for (i = 1; i <= o.lines; i++) seg(i)

      return ins(el, g)

    }

    Spinner.prototype.opacity = function(el, i, val, o) {

      var c = el.firstChild

      o = o.shadow && o.lines || 0

      if (c && i+o < c.childNodes.length) {

        c = c.childNodes[i+o]; c = c && c.firstChild; c = c && c.firstChild

        if (c) c.opacity = val

      }

    }

  }

  var probe = css(createEl('group'), {behavior: 'url(#default#VML)'})

  if (!vendor(probe, 'transform') && probe.adj) initVML()

  else useCssAnimations = vendor(probe, 'animation')

  return Spinner

}));