/* http://nanobar.micronube.com/  ||  https://github.com/jacoborus/nanobar/    MIT LICENSE */
(function(root) {
    'use strict'
    // container styles
    var css = '.nanobar{width:100%;height:4px;z-index:9999;top:0}'

    // add required css in head div
    function addCss() {
        var s = document.getElementById('nanobarcss')

        // check whether style tag is already inserted
        if (s === null) {
            s = document.createElement('style')
            s.type = 'text/css'
            s.id = 'nanobarcss'
            document.head.insertBefore(s, document.head.firstChild)
                // the world
            if (!s.styleSheet) return s.appendChild(document.createTextNode(css))
                // IE
            s.styleSheet.cssText = css
        }
    }

    function addClass(el, cls) {
        if (el.classList) el.classList.add(cls)
        else el.className += ' ' + cls
    }

    // create a progress bar
    // this will be destroyed after reaching 100% progress
    function createBar(rm) {
        // create progress element
        var el = document.createElement('div'),
            width = 0,
            here = 0,
            on = 0,
            bar = {
                el: el,
                go: go
            }

        addClass(el, 'bar')

        // animation loop
        function move() {
            var dist = width - here

            if (dist < 0.1 && dist > -0.1) {
                place(here)
                on = 0
                if (width >= 100) {
                    el.style.height = 0
                    setTimeout(function() {
                        rm(el)
                    }, 300)
                }
            } else {
                place(width - dist / 4)
                setTimeout(go, 16)
            }
        }

        // set bar width
        function place(num) {
            width = num
            el.style.width = width + '%'
        }

        function go(num) {
            if (num >= 0) {
                here = num
                if (!on) {
                    on = 1
                    move()
                }
            } else if (on) {
                move()
            }
        }
        return bar
    }

    function Nanobar(opts) {
        opts = opts || {}
            // set options
        var el = document.createElement('div'),
            applyGo,
            nanobar = {
                el: el,
                go: function(p) {
                    // expand bar
                    applyGo(p)
                        // create new bar when progress reaches 100%
                    if (p >= 100) {
                        init()
                    }
                }
            }

        // remove element from nanobar container
        function rm(child) {
            el.removeChild(child)
        }

        // create and insert progress var in nanobar container
        function init() {
            var bar = createBar(rm)
            el.appendChild(bar.el)
            applyGo = bar.go
        }

        addCss()

        addClass(el, 'nanobar')
        if (opts.id) el.id = opts.id
        if (opts.classname) addClass(el, opts.classname)

        // insert container
        if (opts.target) {
            // inside a div
            el.style.position = 'relative'
            opts.target.insertBefore(el, opts.target.firstChild)
        } else {
            // on top of the page
            el.style.position = 'fixed'
            document.getElementsByTagName('body')[0].appendChild(el)
        }

        init()
        return nanobar
    }

    if (typeof exports === 'object') {
        // CommonJS
        module.exports = Nanobar
    } else if (typeof define === 'function' && define.amd) {
        // AMD. Register as an anonymous module.
        define([], function() { return Nanobar })
    } else {
        // Browser globals
        root.Nanobar = Nanobar
    }
}(this))