var active_summary=null;
var summaries_request=null;
function is_ie()
{
	if(navigator.userAgent.indexOf('MSIE')!=-1) return true; else return false;
}
function set_tab_menus()
{
	menu_items=document.getElementById('news_tabs').getElementsByTagName('li');
	for(i=0;menu_items.length>i;i++)
	{
		menu_item=menu_items[i].getElementsByTagName('a');
		if(menu_item.length>0) menu_item[0].onclick=tab_menus_clicked;
	}
}

function tab_menus_clicked()
{
	change_selected_menu(this);
	switch(this.innerHTML)
	{
		case 'Gündem':showing_category=3;break;
		case 'Politika':showing_category=4;break;
		case 'Ekonomi':showing_category=5;break;
		case 'Spor':showing_category=6;break;
		case 'Kültür Sanat':showing_category=7;break;
		case 'Yaşam':showing_category=8;break;
		case 'Magazin':showing_category=9;break;
		case 'Eğitim':showing_category=10;break;
		case 'Sağlık':showing_category=11;break;
		case 'Nostalji':showing_category=12;break;
		default:return false;
	}
	uls=document.getElementById('tab_container').getElementsByTagName('ul');
	for(j=0;uls.length>j;j++)
	{
		uls[j].style.display='none';
		uls[j].style.visibility='hidden';
	}
	if((showing_summaries=document.getElementById('news_summaries'+showing_category))!=null)
	{
		showing_summaries.style.display='block';
		showing_summaries.style.visibility='visible';
		showing_summaries.style.opacity=0;
		increase_opacity('news_summaries'+showing_category,0.1);
	}
	else
	{
		show_news_loading_frame();
		if(summaries_request==null) 
		{
			summaries_request=new Ajax();
			summaries_request.timeout=6000;
			summaries_request.state_changing=summaries_request_state_chaning;
			summaries_request.expired=summaries_request_expired();
		}
		summaries_request.send(get_host_name()+'libraries/news_summaries_http.php?http=1&showing_category='+showing_category,null);
	}
	return false;
}
function hide_news_loading_frame()
{
	document.getElementById('news_loading_frame').style.display='none';
	document.getElementById('news_loading_frame').style.visibility='hidden';
	set_tab_menus();
}
function show_news_loading_frame()
{
	if(!document.getElementById('news_loading_frame')) document.getElementById('tab_container').innerHTML+='<div id="news_loading_frame" style="overflow:hidden;height:350px;"><img style="border:0;margin:110px 10px 300px 280px;float:left;" src="images/common/ajax_loading.gif" alt="Yükleniyor..." /><span style="margin-top:115px;display:block;font:bold 12px tahoma;">Yükleniyor...</span></div>';	
	document.getElementById('news_loading_frame').style.display='block';
	document.getElementById('news_loading_frame').style.visibility='visible';
}
function change_selected_menu(selected_menu)
{
	menu_items=document.getElementById('news_tabs').getElementsByTagName('li');
	for(i=0;menu_items.length>i;i++)
	{
		menu_items[i].className='';
	}
	selected_menu.parentNode.className='selected';
}
function summaries_request_expired()
{
	summaries_request.status='aborted';
	summaries_request.http_object.abort();
}
function summaries_request_state_chaning()
{
	if(summaries_request.http_object.readyState==4)
	{
		if(summaries_request.http_object.status==200)
		{
			document.getElementById('tab_container').innerHTML+=summaries_request.http_object.responseText;
			uls=document.getElementById('tab_container').getElementsByTagName('ul');
			for(j=0;uls.length>j;j++)
			if(uls[j].style.visibility!='hidden')
			{
				uls[j].style.opacity=0;
				increase_opacity(uls[j].id,0.1);
			}
		}
		hide_news_loading_frame();
	}
}

function increase_opacity(object_id,amount)
{
	if(parseFloat(document.getElementById(object_id).style.opacity)+amount>=1)
	{
		document.getElementById(object_id).style.opacity=1;
	}
	else
	{
		document.getElementById(object_id).style.opacity=parseFloat(document.getElementById(object_id).style.opacity)+amount;
		setTimeout('increase_opacity(\''+object_id+'\','+amount+')',5);
	}
}