/**
 * Copyright (c) 2011-2014 Felix Gnass
 * Licensed under the MIT license
 */

/*
 * The MIT License

Copyright (c) 2011-2014 Felix Gnass [fgnass at neteye dot de]

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
 */
(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 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})

      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

}));