$(function(){
    
    function nav_position(){
        if($(window).width() > 767) {
            if($(window).scrollTop() > $('.header nav').height() + 233){
                $('.horizontal_nav_background').slideDown(300);
            } else {
                $('.horizontal_nav_background').slideUp(300);
                if($('.horizontal_nav_background').css('display') === 'none'){
                    $('.horizontal_nav_background').css('display', '');
                }
            }
        }
    }
    
    nav_position();
    
    $(window).scroll(function(){
        nav_position();
    });
    
    $(window).resize(function(){
        nav_position();
    });
    
    $('.toggle_nav').on('click', function(){
        if($('.horizontal_nav .nav_container').css('display') === 'none'){
            $('.toggle_icon').attr('class', 'fa fa-times toggle_icon');
        } else {
            $('.toggle_icon').attr('class', 'fa fa-bars toggle_icon');
        }
        $('.horizontal_nav .nav_container').slideToggle(function(){
        if($('.horizontal_nav .nav_container').css('display') === 'none'){
            $('.horizontal_nav .nav_container').css('display', '');
        }
        });
    });
    
    function change_image(){
        current_header_image++;
        if(current_header_image >= header_images.length){
            current_header_image = 0;
        }
        $(".header_transition").css("background-image", "url(" + header_images_path + header_images[current_header_image] + ")");
        $(".header_transition").fadeIn(1000, function(){
            $(".header_background").css("background-image", "url(" + header_images_path + header_images[current_header_image] + ")");
            $(".header_transition").fadeOut(300);
        });
        $(".horizontal_nav_background_transition").css("background-image", "url(" + header_images_path + header_images[current_header_image] + ")");
        $(".horizontal_nav_background_transition").fadeIn(1000, function(){
            $(".horizontal_nav_background").css("background-image", "url(" + header_images_path + header_images[current_header_image] + ")");
            $(".horizontal_nav_background_transition").fadeOut(300);
        });
        window.setTimeout(function(){change_image();}, interval);
    }
    
    var header_images_path = "img/environment/";
    var header_images = ["background_blue.jpg", "background_red.jpg", "background_yellow.jpg"];
    var interval = 10000;
    var current_header_image = Math.floor(Math.random()*header_images.length);
    $(".header_background").css("background-image", "url(" + header_images_path + header_images[current_header_image] + ")");
    $(".horizontal_nav_background").css("background-image", "url(" + header_images_path + header_images[current_header_image] + ")");
    window.setTimeout(function(){change_image();}, interval);

    
});