(function(addon) {

    var component;

    if (window.UIkit) {
        component = addon(UIkit);
    }

    if (typeof define == "function" && define.amd) {
        define("uikit-sticky", ["uikit"], function(){
            return component || addon(UIkit);
        });
    }

})(function(UI){

    "use strict";

    var $win         = UI.$win,
        $doc         = UI.$doc,
        sticked      = [],
        direction    = 1;

    UI.component('sticky', {

        defaults: {
            top          : 0,
            bottom       : 0,
            animation    : '',
            clsinit      : 'uk-sticky-init',
            clsactive    : 'uk-active',
            clsinactive  : '',
            getWidthFrom : '',
            showup      : false,
            boundary     : false,
            media        : false,
            target       : false,
            disabled     : false
        },

        boot: function() {

            // should be more efficient than using $win.scroll(checkscrollposition):
            UI.$doc.on('scrolling.uk.document', function(e, data) {
                if (!data || !data.dir) return;
                direction = data.dir.y;
                checkscrollposition();
            });

            UI.$win.on('resize orientationchange', UI.Utils.debounce(function() {

                if (!sticked.length) return;

                for (var i = 0; i < sticked.length; i++) {
                    sticked[i].reset(true);
                    sticked[i].self.computeWrapper();
                }

                checkscrollposition();
            }, 100));

            // init code
            UI.ready(function(context) {

                setTimeout(function(){

                    UI.$("[data-uk-sticky]", context).each(function(){

                        var $ele = UI.$(this);

                        if (!$ele.data("sticky")) {
                            UI.sticky($ele, UI.Utils.options($ele.attr('data-uk-sticky')));
                        }
                    });

                    checkscrollposition();
                }, 0);
            });
        },

        init: function() {

            var boundary = this.options.boundary, boundtoparent;

            this.wrapper = this.element.wrap('<div class="uk-sticky-placeholder"></div>').parent();
            this.computeWrapper();
            this.wrapper.css({
                'margin-top'    : this.element.css('margin-top'),
                'margin-bottom' : this.element.css('margin-bottom'),
                'margin-left'   : this.element.css('margin-left'),
                'margin-right'  : this.element.css('margin-right')
            })
            this.element.css('margin', 0);

            if (boundary) {

                if (boundary === true || boundary[0] === '!') {

                    boundary      = boundary === true ? this.wrapper.parent() : this.wrapper.closest(boundary.substr(1));
                    boundtoparent = true;

                } else if (typeof boundary === "string") {
                    boundary = UI.$(boundary);
                }
            }

            this.sticky = {
                self          : this,
                options       : this.options,
                element       : this.element,
                currentTop    : null,
                wrapper       : this.wrapper,
                init          : false,
                getWidthFrom  : UI.$(this.options.getWidthFrom || this.wrapper),
                boundary      : boundary,
                boundtoparent : boundtoparent,
                top           : 0,
                calcTop       : function() {

                    var top = this.options.top;

                    // dynamic top parameter
                    if (this.options.top && typeof(this.options.top) == 'string') {

                        // e.g. 50vh
                        if (this.options.top.match(/^(-|)(\d+)vh$/)) {
                            top = window.innerHeight * parseInt(this.options.top, 10)/100;
                        // e.g. #elementId, or .class-1,class-2,.class-3 (first found is used)
                        } else {

                            var topElement = UI.$(this.options.top).first();

                            if (topElement.length && topElement.is(':visible')) {
                                top = -1 * ((topElement.offset().top + topElement.outerHeight()) - this.wrapper.offset().top);
                            }
                        }

                    }

                    this.top = top;
                },

                reset: function(force) {

                    this.calcTop();

                    var finalize = function() {
                        this.element.css({"position":"", "top":"", "width":"", "left":"", "margin":"0"});
                        this.element.removeClass([this.options.animation, 'uk-animation-reverse', this.options.clsactive].join(' '));
                        this.element.addClass(this.options.clsinactive);
                        this.element.trigger('inactive.uk.sticky');

                        this.currentTop = null;
                        this.animate    = false;

                    }.bind(this);


                    if (!force && this.options.animation && UI.support.animation && !UI.Utils.isInView(this.wrapper)) {

                        this.animate = true;

                        this.element.removeClass(this.options.animation).one(UI.support.animation.end, function(){
                            finalize();
                        }).width(); // force redraw

                        this.element.addClass(this.options.animation+' '+'uk-animation-reverse');
                    } else {
                        finalize();
                    }
                },

                check: function() {

                    if (this.options.disabled) {
                        return false;
                    }

                    if (this.options.media) {

                        switch(typeof(this.options.media)) {
                            case 'number':
                                if (window.innerWidth < this.options.media) {
                                    return false;
                                }
                                break;
                            case 'string':
                                if (window.matchMedia && !window.matchMedia(this.options.media).matches) {
                                    return false;
                                }
                                break;
                        }
                    }

                    var scrollTop      = $win.scrollTop(),
                        documentHeight = $doc.height(),
                        dwh            = documentHeight - window.innerHeight,
                        extra          = (scrollTop > dwh) ? dwh - scrollTop : 0,
                        elementTop     = this.wrapper.offset().top,
                        etse           = elementTop - this.top - extra,
                        active         = (scrollTop  >= etse);

                    if (active && this.options.showup) {

                        // set inactiv if scrolling down
                        if (direction == 1) {
                            active = false;
                        }

                        // set inactive when wrapper is still in view
                        if (direction == -1 && !this.element.hasClass(this.options.clsactive) && UI.Utils.isInView(this.wrapper)) {
                            active = false;
                        }
                    }

                    return active;
                }
            };

            this.sticky.calcTop();

            sticked.push(this.sticky);
        },

        update: function() {
            checkscrollposition(this.sticky);
        },

        enable: function() {
            this.options.disabled = false;
            this.update();
        },

        disable: function(force) {
            this.options.disabled = true;
            this.sticky.reset(force);
        },

        computeWrapper: function() {

            this.wrapper.css({
                'height'        : ['absolute','fixed'].indexOf(this.element.css('position')) == -1 ? this.element.outerHeight() : '',
                'float'         : this.element.css('float') != 'none' ? this.element.css('float') : ''
            });

            if (this.element.css('position') == 'fixed') {
                this.element.css({
                    width: this.sticky.getWidthFrom.length ? this.sticky.getWidthFrom.width() : this.element.width()
                });
            }
        }
    });

    function checkscrollposition(direction) {

        var stickies = arguments.length ? arguments : sticked;

        if (!stickies.length || $win.scrollTop() < 0) return;

        var scrollTop       = $win.scrollTop(),
            documentHeight  = $doc.height(),
            windowHeight    = $win.height(),
            dwh             = documentHeight - windowHeight,
            extra           = (scrollTop > dwh) ? dwh - scrollTop : 0,
            newTop, containerBottom, stickyHeight, sticky;

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

            sticky = stickies[i];

            if (!sticky.element.is(":visible") || sticky.animate) {
                continue;
            }

            if (!sticky.check()) {

                if (sticky.currentTop !== null) {
                    sticky.reset();
                }

            } else {

                if (sticky.top < 0) {
                    newTop = 0;
                } else {
                    stickyHeight = sticky.element.outerHeight();
                    newTop = documentHeight - stickyHeight - sticky.top - sticky.options.bottom - scrollTop - extra;
                    newTop = newTop < 0 ? newTop + sticky.top : sticky.top;
                }

                if (sticky.boundary && sticky.boundary.length) {

                    var bTop = sticky.boundary.offset().top;

                    if (sticky.boundtoparent) {
                        containerBottom = documentHeight - (bTop + sticky.boundary.outerHeight()) + parseInt(sticky.boundary.css('padding-bottom'));
                    } else {
                        containerBottom = documentHeight - bTop;
                    }

                    newTop = (scrollTop + stickyHeight) > (documentHeight - containerBottom - (sticky.top < 0 ? 0 : sticky.top)) ? (documentHeight - containerBottom) - (scrollTop + stickyHeight) : newTop;
                }


                if (sticky.currentTop != newTop) {

                    sticky.element.css({
                        position : "fixed",
                        top      : newTop,
                        width    : sticky.getWidthFrom.length ? sticky.getWidthFrom.width() : sticky.element.width()
                    });

                    if (!sticky.init) {

                        sticky.element.addClass(sticky.options.clsinit);

                        if (location.hash && scrollTop > 0 && sticky.options.target) {

                            var $target = UI.$(location.hash);

                            if ($target.length) {

                                setTimeout((function($target, sticky){

                                    return function() {

                                        sticky.element.width(); // force redraw

                                        var offset       = $target.offset(),
                                            maxoffset    = offset.top + $target.outerHeight(),
                                            stickyOffset = sticky.element.offset(),
                                            stickyHeight = sticky.element.outerHeight(),
                                            stickyMaxOffset = stickyOffset.top + stickyHeight;

                                        if (stickyOffset.top < maxoffset && offset.top < stickyMaxOffset) {
                                            scrollTop = offset.top - stickyHeight - sticky.options.target;
                                            window.scrollTo(0, scrollTop);
                                        }
                                    };

                                })($target, sticky), 0);
                            }
                        }
                    }

                    sticky.element.addClass(sticky.options.clsactive).removeClass(sticky.options.clsinactive);
                    sticky.element.trigger('active.uk.sticky');
                    sticky.element.css('margin', '');

                    if (sticky.options.animation && sticky.init && !UI.Utils.isInView(sticky.wrapper)) {
                        sticky.element.addClass(sticky.options.animation);
                    }

                    sticky.currentTop = newTop;
                }
            }

            sticky.init = true;
        }
    }

    return UI.sticky;
});
