avia-snippet-sticky-header

(function($)
{
    "use strict";

    $( function()
    {
        // decreases header size when user scrolls down
        avia_header_size();
    });


    function av_change_class($element, change_method, class_name)
    {
        if($element[0].classList)
        {
            if(change_method == "add")
            {
                $element[0].classList.add(class_name);
            }
            else
            {
                $element[0].classList.remove(class_name);
            }
        }
        else
        {
            if(change_method == "add")
            {
                $element.addClass(class_name);
            }
            else
            {
                $element.removeClass(class_name);
            }
        }
    }


    function avia_header_size()
    {
        var win             = $(window),
            header          = $('.html_header_top.html_header_sticky #header'),
            unsticktop      = $('.av_header_unstick_top');

        if( ! header.length && ! unsticktop.length )
        {
            return;
        }

        var logo            = $('#header_main .container .logo img, #header_main .container .logo svg, #header_main .container .logo a'),
            elements        = $('#header_main .container:not(#header_main_alternate>.container), #header_main .main_menu ul:first-child > li > a:not(.avia_mega_div a, #header_main_alternate a), #header_main #menu-item-shop .cart_dropdown_link'),
            el_height       = $(elements).first().height(),
            isMobile        = $.avia_utilities.isMobile,
            scroll_top      = $('#scroll-top-link'),
            transparent     = header.is('.av_header_transparency'),
            shrinking       = header.is('.av_header_shrinking'),
            header_meta     = header.find('#header_meta'),
            topbar_height   = header_meta.length ? header_meta.outerHeight() : 0,

            set_height = function()
            {
                var st = win.scrollTop(),
                    newH = 0,
                    st_real = st;

                if( unsticktop )
                {
                    st -= topbar_height;
                }

                if( st < 0 )
                {
                    st = 0;
                }

                if( shrinking && ! isMobile )
                {
                    if( st < el_height/4 )
                    {
                        newH = el_height - st;
                        if( st <= 0 )
                        {
                            newH = el_height;
                        }

                        av_change_class( header, 'remove', 'header-scrolled' );
                        //header.removeClass('header-scrolled');
                    }
                    else
                    {
                        newH = el_height/1.333;
                        //header.addClass('header-scrolled');
                        av_change_class( header, 'add', 'header-scrolled' );
                    }

                    if( st - 30 < el_height )
                    {
                        av_change_class( header, 'remove', 'header-scrolled-full' );
                    }
                    else
                    {
                        av_change_class( header, 'add', 'header-scrolled-full' );
                    }


                    elements.css({'height': newH + 'px', 'lineHeight': newH + 'px'});
                    logo.css({'maxHeight': newH + 'px'});
                }

                if( unsticktop.length )
                {
                    if( st <= 0 )
                    {
                        if( st_real <= 0 )
                        {
                            st_real = 0;
                        }

                        unsticktop.css({"margin-top":"-"+st_real+"px"});
                    }
                    else
                    {
                        unsticktop.css({"margin-top":"-"+topbar_height+"px"});
                    }
                }

                if( transparent )
                {
                    if( st > 50 )
                    {
                        //header.removeClass('av_header_transparency');
                        av_change_class( header, 'remove', 'av_header_transparency' );
                    }
                    else
                    {
                        //header.addClass('av_header_transparency');
                        av_change_class( header, 'add', 'av_header_transparency' );
                    }
                }


            };

        if( $('body').is( '.avia_deactivate_menu_resize' ) )
        {
            shrinking = false;
        }

        if( ! transparent && ! shrinking && ! unsticktop.length )
        {
            return;
        }

        win.on( 'debouncedresize',  function()
        {
            el_height = $( elements ).attr( 'style',"" ).first().height();
            set_height();
        });

        win.on( 'scroll',  function()
        {
            window.requestAnimationFrame( set_height );
        });

        set_height();
    }


})(jQuery);