// fgnass.github.com/spin.js#v1.2.6
// usage: new Spinner({color:'#fff', lines: 12}).spin(target);
!function(window, document, undefined) {

    /**
     * Copyright (c) 2011 Felix Gnass [fgnass at neteye dot de]
     * Licensed under the MIT license
     */

    var prefixes = ['webkit', 'Moz', 'ms', 'O'] /* Vendor prefixes */
        , animations = {} /* Animation rules keyed by their name */
        , useCssAnimations

    /**
     * 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

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

    /**
     * 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
    }

    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
        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: 'auto',          // center vertically
        left: 'auto'          // center horizontally
    }

    /** The constructor */
    var Spinner = function Spinner(o) {
        if (!this.spin) return new Spinner(o)
        this.opts = merge(o || {}, Spinner.defaults, defaults)
    }

    Spinner.defaults = {}

    merge(Spinner.prototype, {
        spin: function(target) {
            this.stop()
            var self = this
                , o = self.opts
                , el = self.el = css(createEl(0, {className: o.className}), {position: 'relative', width: 0, zIndex: o.zIndex})
                , mid = o.radius+o.length+o.width
                , ep // element position
                , tp // target position

            if (target) {
                target.insertBefore(el, target.firstChild||null)
                tp = pos(target)
                ep = pos(el)
                css(el, {
                    left: (o.left == 'auto' ? tp.x-ep.x + (target.offsetWidth >> 1) : parseInt(o.left, 10) + mid) + 'px',
                    top: (o.top == 'auto' ? tp.y-ep.y + (target.offsetHeight >> 1) : parseInt(o.top, 10) + mid)  + 'px'
                })
            }

            el.setAttribute('aria-role', 'progressbar')
            self.lines(el, self.opts)

            if (!useCssAnimations) {
                // No CSS animation support, use setTimeout() instead
                var i = 0
                    , fps = o.fps
                    , f = fps/o.speed
                    , ostep = (1-o.opacity) / (f*o.trail / 100)
                    , astep = f/o.lines

                    ;(function anim() {
                    i++;
                    for (var s=o.lines; s; s--) {
                        var alpha = Math.max(1-(i+s*astep)%f * ostep, o.opacity)
                        self.opacity(el, o.lines-s, alpha, o)
                    }
                    self.timeout = self.el && setTimeout(anim, ~~(1000/fps))
                })()
            }
            return self
        },

        stop: function() {
            var el = this.el
            if (el) {
                clearTimeout(this.timeout)
                if (el.parentNode) el.parentNode.removeChild(el)
                this.el = undefined
            }
            return this
        },

        lines: function(el, o) {
            var i = 0
                , 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, i, 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(o.color, '0 0 1px rgba(0,0,0,.1)')))
            }
            return el
        },

        opacity: function(el, i, val) {
            if (i < el.childNodes.length) el.childNodes[i].style.opacity = val
        }

    })

        /////////////////////////////////////////////////////////////////////////
        // VML rendering for IE
        /////////////////////////////////////////////////////////////////////////

    /**
     * Check and init VML support
     */
    ;(function() {

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

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

        if (!vendor(s, 'transform') && s.adj) {

            // VML support detected. Insert CSS rule ...
            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: o.color, 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
                }
            }
        }
        else
            useCssAnimations = vendor(s, 'animation')
    })()

    if (typeof define == 'function' && define.amd)
        define(function() { return Spinner })
    else
        window.Spinner = Spinner

}(window, document)