; (function ($, window, document, undefined) {

'use strict';

Foundation.libs['magellan-expedition'] = {
    name: 'magellan-expedition',

    version: '5.5.0',

    settings: {
        active_class: 'active',
        threshold: 0, // pixels from the top of the expedition for it to become fixes
        destination_threshold: 20, // pixels from the top of destination for it to be considered active
        throttle_delay: 30, // calculation throttling to increase framerate
        fixed_top: 0, // top distance in pixels assigend to the fixed element on scroll
        offset_by_height: true,  // whether to offset the destination by the expedition height. Usually you want this to be true, unless your expedition is on the side.
        duration: 700, // animation duration time
        easing: 'swing' // animation easing
    },

    init: function (scope, method, options) {
        Foundation.inherit(this, 'throttle');
        this.bindings(method, options);
    },

    events: function () {
        var self = this,
            S = self.S,
            settings = self.settings;

        // initialize expedition offset
        self.set_expedition_position();

        S(self.scope)
            .off('.magellan')
            .on('click.fndtn.magellan', '[' + self.add_namespace('data-magellan-arrival') + '] a[href^="#"]', function (e) {
                e.preventDefault();
                var expedition = $(this).closest('[' + self.attr_name() + ']'),
                    settings = expedition.data('magellan-expedition-init'),
                    hash = this.hash.split('#').join(''),
                    target = $('a[name="' + hash + '"]');

                if (target.length === 0) {
                    target = $('#' + hash);

                }

                // Account for expedition height if fixed position
                var scroll_top = target.offset().top - settings.destination_threshold + 1;
                if (settings.offset_by_height) {
                    scroll_top = scroll_top - expedition.outerHeight();
                }

                $('html, body').stop().animate({
                    'scrollTop': scroll_top
                }, settings.duration, settings.easing, function () {
                    if (history.pushState) {
                        history.pushState(null, null, '#' + hash);
                    }
                    else {
                        location.hash = '#' + hash;
                    }
                });
            })
            .on('scroll.fndtn.magellan', self.throttle(this.check_for_arrivals.bind(this), settings.throttle_delay));

        $(window)
            .on('resize.fndtn.magellan', self.throttle(this.set_expedition_position.bind(this), settings.throttle_delay));
    },

    check_for_arrivals: function () {
        var self = this;
        self.update_arrivals();
        self.update_expedition_positions();
    },

    set_expedition_position: function () {
        var self = this;
        $('[' + this.attr_name() + '=fixed]', self.scope).each(function (idx, el) {
            var expedition = $(this),
                settings = expedition.data('magellan-expedition-init'),
                styles = expedition.attr('styles'), // save styles
                top_offset, fixed_top;

            expedition.attr('style', '');
            top_offset = expedition.offset().top + settings.threshold;

            //set fixed-top by attribute
            fixed_top = parseInt(expedition.data('magellan-fixed-top'));
            if (!isNaN(fixed_top))
                self.settings.fixed_top = fixed_top;

            expedition.data(self.data_attr('magellan-top-offset'), top_offset);
            expedition.attr('style', styles);
        });
    },

    update_expedition_positions: function () {
        var self = this,
            window_top_offset = $(window).scrollTop();

        $('[' + this.attr_name() + '=fixed]', self.scope).each(function () {
            var expedition = $(this),
                settings = expedition.data('magellan-expedition-init'),
                styles = expedition.attr('style'), // save styles
                top_offset = expedition.data('magellan-top-offset');

            //scroll to the top distance
            if (window_top_offset + self.settings.fixed_top >= top_offset) {
                // Placeholder allows height calculations to be consistent even when
                // appearing to switch between fixed/non-fixed placement
                var placeholder = expedition.prev('[' + self.add_namespace('data-magellan-expedition-clone') + ']');
                if (placeholder.length === 0) {
                    placeholder = expedition.clone();
                    placeholder.removeAttr(self.attr_name());
                    placeholder.attr(self.add_namespace('data-magellan-expedition-clone'), '');
                    expedition.before(placeholder);
                }
                expedition.css({position: 'fixed', top: settings.fixed_top}).addClass('fixed');
            } else {
                expedition.prev('[' + self.add_namespace('data-magellan-expedition-clone') + ']').remove();
                expedition.attr('style', styles).css('position', '').css('top', '').removeClass('fixed');
            }
        });
    },

    update_arrivals: function () {
        var self = this,
            window_top_offset = $(window).scrollTop();

        $('[' + this.attr_name() + ']', self.scope).each(function () {
            var expedition = $(this),
                settings = expedition.data(self.attr_name(true) + '-init'),
                offsets = self.offsets(expedition, window_top_offset),
                arrivals = expedition.find('[' + self.add_namespace('data-magellan-arrival') + ']'),
                active_item = false;
            offsets.each(function (idx, item) {
                if (item.viewport_offset >= item.top_offset) {
                    var arrivals = expedition.find('[' + self.add_namespace('data-magellan-arrival') + ']');
                    arrivals.not(item.arrival).removeClass(settings.active_class);
                    item.arrival.addClass(settings.active_class);
                    active_item = true;
                    return true;
                }
            });

            if (!active_item) arrivals.removeClass(settings.active_class);
        });
    },

    offsets: function (expedition, window_offset) {
        var self = this,
            settings = expedition.data(self.attr_name(true) + '-init'),
            viewport_offset = window_offset;

        return expedition.find('[' + self.add_namespace('data-magellan-arrival') + ']').map(function (idx, el) {
            var name = $(this).data(self.data_attr('magellan-arrival')),
                dest = $('[' + self.add_namespace('data-magellan-destination') + '=' + name + ']');
            if (dest.length > 0) {
                var top_offset = dest.offset().top - settings.destination_threshold;
                if (settings.offset_by_height) {
                    top_offset = top_offset - expedition.outerHeight();
                }
                top_offset = Math.floor(top_offset);
                return {
                    destination: dest,
                    arrival: $(this),
                    top_offset: top_offset,
                    viewport_offset: viewport_offset
                }
            }
        }).sort(function (a, b) {
            if (a.top_offset < b.top_offset) return -1;
            if (a.top_offset > b.top_offset) return 1;
            return 0;
        });
    },

    data_attr: function (str) {
        if (this.namespace.length > 0) {
            return this.namespace + '-' + str;
        }

        return str;
    },

    off: function () {
        this.S(this.scope).off('.magellan');
        this.S(window).off('.magellan');
    },

    reflow: function () {
        var self = this;
        // remove placeholder expeditions used for height calculation purposes
        $('[' + self.add_namespace('data-magellan-expedition-clone') + ']', self.scope).remove();
    }
};

}(jQuery, window, window.document));