$(document).ready(function() {


	class stickynavigation {
		
		constructor() {
			this.currentid = null;
			this.currenttab = null;
			this.tabcontainerheight = 100;
			let self = this;
			$('.tb_a').click(function() { 
				self.ontabclick(event, $(this)); 
			});
			$(window).scroll(() => { this.onscroll(); });
			$(window).resize(() => { this.onresize(); });
		}
		
		ontabclick(event, element) {
			event.preventdefault();
			let scrolltop = $(element.attr('href')).offset().top - this.tabcontainerheight + 1;
			$('html, body').animate({ scrolltop: scrolltop }, 600);
		}
		
		onscroll() {
			this.checktabcontainerposition();
			this.findcurrenttabselector();
		}
		
		onresize() {
			if(this.currentid) {
				this.setslidercss();
			}
		}
		
		checktabcontainerposition() {
			let offset = $('.tb_nav').offset().top + $('.tb_nav').height() - this.tabcontainerheight;
			if($(window).scrolltop() > offset) {
				$('.tb_main').addclass('tb_main_top');
			} 
			else {
				$('.tb_main').removeclass('tb_main_top');
			}
		}
		
		findcurrenttabselector(element) {
			let newcurrentid;
			let newcurrenttab;
			let self = this;
			$('.tb_a').each(function() {
				let id = $(this).attr('href');
				let offsettop = $(id).offset().top - self.tabcontainerheight;
				let offsetbottom = $(id).offset().top + $(id).height() - self.tabcontainerheight;
				if($(window).scrolltop() > offsettop && $(window).scrolltop() < offsetbottom) {
					newcurrentid = id;
					newcurrenttab = $(this);
				}
			});
			if(this.currentid != newcurrentid || this.currentid === null) {
				this.currentid = newcurrentid;
				this.currenttab = newcurrenttab;
				this.setslidercss();
			}
		}
		
		setslidercss() {
			let width = 0;
			let left = 0;
			if(this.currenttab) {
				width = this.currenttab.css('width');
				left = this.currenttab.offset().left;
			}
			$('.tb_line').css('width', width);
			$('.tb_line').css('left', left);
		}
		
	}

	new stickynavigation();

	
    $('header .mbtn').click(function(event) {
        $('body').toggleclass('on-menu');
        return false;
    });

})