/*
	Javascript functionality common to all files
	If adding to this, please bear in mind progressive enhancement 
	- test for functionality before using it to avoid errors
*/

function bookmarkPage(){
	//used by "bookmark page" link in page tools
	 if(window.sidebar){
		 //syntax for FF. 3rd empty string argument is required
		window.sidebar.addPanel(document.title, location.href,'');
	}else{		
		if(window.external){
			//syntax for IE
			window.external.AddFavorite(location.href,document.title);
		}	
	}	
}

function printPage(){
	//used by "print page" link in page tools
	window.print();
}	

function findExitRamps(){
	//identify any links with an exit ramp
	
	aryExtLinks=getElementsByClassName(document,'external');
	/*
		possible HTML is:
		<a class="external"></a>
		<span class="external"><a></a></span>
		<a><span class="external"></span></a>
	*/
	for(i=0;i<aryExtLinks.length;i++){
		switch(aryExtLinks[i].tagName.toLowerCase()){
			case 'span':
				//is this within the link?
				if(aryExtLinks[i].parentNode.tagName.toLowerCase()=='a'){
					operativeElement=aryExtLinks[i].parentNode;
				}else{
					//is it around a link?
					if(aryExtLinks[i].firstChild && aryExtLinks[i].firstChild.tagName && aryExtLinks[i].firstChild.tagName.toLowerCase()=='a'){
						operativeElement=aryExtLinks[i].firstChild;					
					}else{
						//if neither condition is met, class must have been applied in error	
						operativeElement=false;
					}
				}
			break;
			case 'a':
					operativeElement=aryExtLinks[i];
			break;			
			default:
				//class must have been applied in error	
				operativeElement=false;
			break;
		}
		if(operativeElement){
			href=aryExtLinks[i].href;
			aryExtLinks[i].onclick=function(){return showExitWarning(href)};
		}	
	}
}	
	
function showExitWarning(url){
	//shows confirmation message when clicking on external links
	//only do this if exit message is populated
	//this will only be the case where an additional local js file is present. 
	//see defect 268
	if(window.exitMessage){
		if(confirm(exitMessage)){
			return true;
		}else{
			return false;
		}	
	}else{
		//no exit message defined, send user directly to the link
		return true;
	}	
}

var selectBoxSelected=[];
function toggleSelection(selectBox){
	//checks whether the first (default/all) option is selected on the select box passed as selectBox
	//unselects all other options if so
	var unset=false;
	//loop through all options
	if(selectBox){
		for(i=0,j=selectBox.length;i<j;i++){
			if(!selectBoxSelected[i] && selectBox.options[i].selected){
				//this element is the one being selected
				if(i==0){
					//it is the first one, so unset all the others
					unset=true;
				}else{
					//it is not the first one, so unset the first one
					selectBox.options[0].selected=false;
					//record this change
					selectBoxSelected[0]=false;
				}
			}	
			//unset all options if first one is selected
			if(unset && i>0){
				selectBox.options[i].selected=false;
			}
			//record setting of each option in array
			selectBoxSelected[i]=selectBox.options[i].selected;
		}	
	}	
}

function toggleRelatedSelects(){
	//checks whether "this site only" in site select box is selected
	//if so, enables audience and area select boxes
	//if not, disables them
	var siteSelectBox=document.getElementById('rskey');
	var areaSelectBox=getNamedElementId('select','sakey');
	var audienceSelectBox=document.getElementById('saudkey');
	if(siteSelectBox.options[0].selected==true){
		if(areaSelectBox){
			areaSelectBox.disabled=false;
		}
		if(audienceSelectBox){
			audienceSelectBox.disabled=false;
		}
	}else{
		if(areaSelectBox){
			areaSelectBox.disabled=true;
		}
		if(audienceSelectBox){
			audienceSelectBox.disabled=true;
		}		
	}
	return true;
}

function showHelp(){
	//shows or hides the help popup for form field onclick
	//popup also appears on hover - this is for keyboard users
	
	//get a reference to the a tag which was clicked
	el=this;
	//switch off any other help popups
	els=getElementsByClassName(document,'inhelplink');
	already_set=false;
	if(els){
		for(var i=0,j=els.length; i<j; i++){
			//if this popup was on then don't switch it on again
			els[i].className='inhelplink_off';
			elSpans=el.getElementsByTagName('span');
			if(elSpans && elSpans[0]==els[i]){
				already_set=true;
			}
		}
	}
	if(!already_set){
		childEls=el.getElementsByTagName('span');
		if(childEls){
			childEls[0].className='inhelplink';
		}
	}
	//stop link from sending user to top of page
	return false;
}

function prepareHelpLinks(){
	if(document.links){
		linkslist=document.links;
		for(i=0;i<linkslist.length;i++){
			if(linkslist[i].className=='helplink'){
				//add the onclick event
				linkslist[i].onclick=showHelp;
				//remove the class
				linkslistSpan=linkslist[i].getElementsByTagName('span');
				if(linkslistSpan){
					linkslistSpan[0].className='inhelplink_off';
				}
			}
		}
	}
}

function popUpWindow(url,windowName,dependent,height,location,menubar,resizable,screenX,screenY,scrollbars,status,titlebar,toolbar,width){
	//fully-featured popup function
	//pass in 'yes' or 'no' for all arguments except url, windowName, height, screenX, screenY and width
	newWindow=window.open(url,name,'dependent='+dependent+',height='+height+',location='+location+',menubar='+menubar+',resizable='+resizable+',screenX='+screenX+',screenY='+screenY+',scrollbars='+scrollbars+',status='+status+',titlebar='+titlebar+',toolbar='+toolbar+',width='+width);
	return false;
}
							
function getElementsByClassName(node, classname){
	if(node.getElementsByClassName){
		//some browsers now support this
		return node.getElementsByClassName(classname);
	}else{
	    var elsOut = [];
	    var re = new RegExp('(^| )'+classname+'( |$)');
	    var els = node.getElementsByTagName('*');
	    for(var i=0,j=els.length; i<j; i++){
	        if(re.test(els[i].className))elsOut.push(els[i]);
	    }    
	    return elsOut;
	}	    
}

function getNamedElementId(elName,id){	
	//find named element in dom of given type
	//used to avoid conflict between items with same name (IE6 problem). 
	//e.g. sakey on advanced search page
	rtn=false;
	els=document.getElementsByTagName(elName);
	if(els){
		for(i=0,j=els.length;i<j;i++){
			if(els[i].id==id){
				rtn=els[i];
				break;
			}
		}
	}	
	return rtn;
}

function getAttributeCrossBrowser(element,attribute){
	//implemented to deal with IE6's inability to recognise class
	//can also set for if required
	//browser sniffing not used for forwards compatibility
	switch(attribute){
		case 'class':
			out=element.getAttribute('class')?element.getAttribute('class'):element.getAttribute('className');
		break;
		case 'for':
			out=element.getAttribute('for')?element.getAttribute('for'):element.getAttribute('htmlFor');
		break;
		default:
			out=element.getAttribute(attribute);
		break;
	}
	return out;
}

function setAttributeCrossBrowser(element,attribute,value){
	//implemented to deal with IE6's inability to recognise class
	//can also set for if required
	//browser sniffing not used for forwards compatibility
	switch(attribute){
		case 'class':
			element.setAttribute('class',value);
			element.setAttribute('className',value);
		break;
		case 'for':
			element.setAttribute('for',value);
			element.setAttribute('htmlFor',value);
		break;
		default:
			element.setAttribute(attribute,value);
		break;
	}
}

function toggleAttribute(element,attribute,oldValue,newValue){
	//if the old value is present, replace it with the new value
	//otherwise just add the new value
	//could be enhanced to check that oldValue is not a subset of an attribute (e.g. of newValue - visible and invisible are bad choices for values) 
	//will not work if this is the case
	switch(attribute){
		case 'class':
			newClass=newValue;
			//is there already a class attribute?
			currentClass=getAttributeCrossBrowser(element,'class');
			if(currentClass){				
       	    	//is there an old value?
				if(oldValue.length>0 && currentClass.indexOf(oldValue)!==-1){
					//replace it					
					newClass=currentClass.replace(oldValue,newValue);
				}else{
					if(currentClass.indexOf(newValue)==-1){
						//newValue not already in the className	
						//add it						
						newClass=currentClass+' '+newValue;
                	}else{
                		//newValue is already there so keep it as it is
                		newClass=currentClass;
                	}
                }	
			}	
			setAttributeCrossBrowser(element,'class',newClass);
		break;
		default:
			//this isn't finished - doesn't toggle at the moment, just overwrites
			setAttributeCrossBrowser(element,attribute,newValue);
		break;
	}
}

function addPrototypeEffects(){
	if(typeof Prototype !=='undefined'){
		$$('.datepicker').each(function(el){
			var picker = new Control.DatePicker(el, {datePicker: true,
				timePicker: false,
				locale: 'en_GB'
			});
		});
		$$('.timepicker').each(function(el){
			var picker = new Control.DatePicker(el, {datePicker: false,
				timePicker: true,
				use24hrs:true,
				locale: 'en_GB'
			});
		});
			
		$$('.blind').each(function(el){
			el.observe('click',toggleBlinds);
		});
		/*something like this
		new Effect.Move($('event_details'),{ x: 0, y: 0, mode: 'absolute' });
		replace the X and Y values with Event.pointerX(event);
		see http://www.prototypejs.org/api/event/pointerX
		maybe combine with effect.appear - move it first then make it appear 
		try to make this generic - maybe a class on the link?
		http://wiki.github.com/madrobby/scriptaculous/effect-appear
		
		also have a think about absolutise in prototype
		*/
		
	}	
	
}
/*
function addSWFObjects(){
	if(typeof Prototype !=='undefined'){
		$$('.swf_player').each(function(el){
			swfobject.registerObject(el.id);
		});	
	}
}
*/
function toggleBlinds(event){
	var parentEl=event.element();
	if(parentEl.id.startsWith('child')){
		//we actually want to apply the effect to the named element 
		//in the format child_elementname
		var childId=parentEl.id.split('_')[1];
		var el=$(childId);
	}
	
	if(el){
		Effect.toggle(el,'blind');
		parentEl.toggleClassName('collapsed');
		return false;
	}
}

function attachEvents(){
	//goes through the document
	//finds elements which can have enhanced JS functionality 
	//adds that functionality, if supported
	
	//find "print page" link
	linkPrint=document.getElementById('print_page');
	if(linkPrint){
		if(window.print){
			linkPrint.onclick=function(){printPage();};
		}	
	}
	//find "bookmark page" link
	linkBookmark=document.getElementById('bookmark_page');
	if(linkBookmark){
		 if(window.external || window.sidebar){
			linkBookmark.onclick=function(){bookmarkPage();};
		}	 
	}
	
	//necessary as more than one element has name sakey
	sakey=getNamedElementId('select','sakey');

	if(sakey){
		sakey.onchange=function(){toggleSelection(sakey);};
	}
	
	//find site select on advanced search
	rskey=document.getElementById('rskey');
	if(rskey){
		rskey.onchange=function(){toggleRelatedSelects();};
	}
	findExitRamps();
	prepareHelpLinks();
	//now call any additional functions which need to be executed onload
	//these are defined in site, model or sub-model specific js files 
	//in an array called toCall
	if(typeof(toCall)=='object'){
		for(j=0;j<toCall.length;j++){
			try{
				//attempt to call the function
				toCall[j].call();
			}catch(e){
				//error occurred when calling the function 
				//possibly a scope error or function name misspelled
			}
		}
	}
	addPrototypeEffects();
}

//this code always runs and adds in all the functionality if it's available	
if(document.getElementById){
	//browser supports getElementById - attempt to add js functionality
	window.onload=attachEvents;
}