/**
 * author: Marco A. Martinez
 * date:   July 18, 2005
 * description: routines used for news tab menu on front page
 */

var imageDir = '../../images/tab_images/';

// seminar tab's more button
var seminar_more_over = new Image();
var seminar_more_out  = new Image();

seminar_more_out.src  = imageDir + 'tabedge_rt.gif';
seminar_more_over.src = imageDir + 'tabedge_rt_over.gif';

// load images into the cache
var undergrad_over = new Image();
var undergrad_out  = new Image();
var dept_over      = new Image();
var dept_out       = new Image();
var more_over      = new Image();
var more_out       = new Image();
var tab_1_lt_off   = new Image();
var tab_1_lt_on    = new Image();
var tab_1_rt_off   = new Image();
var tab_1_rt_on    = new Image();
var tab_2_rt_off   = new Image();
var tab_2_rt_on    = new Image();

// main button rollovers
undergrad_over.src = imageDir + 'undergrad_news_on_over.gif';
undergrad_out.src  = imageDir + 'undergrad_news_on.gif';
dept_over.src      = imageDir + 'dept_news_on_over.gif';
dept_out.src       = imageDir + 'dept_news_on.gif';

// tab edge rollovers
tab_1_lt_off.src = imageDir +'tabedge_lt_1_off.gif';
tab_1_lt_on.src  = imageDir +'tabedge_lt_1_on.gif';
tab_1_rt_off.src = imageDir +'tabedge_rt_1_off.gif';
tab_1_rt_on.src  = imageDir +'tabedge_rt_1_on.gif';
tab_2_rt_off.src = imageDir +'tabedge_rt_2_off.gif';
tab_2_rt_on.src  = imageDir +'tabedge_rt_2_on.gif';

// more button rollovers
more_over.src = imageDir + 'tabedge_rt_over.gif';
more_out.src  = imageDir + 'tabedge_rt.gif';


var currentLink = "/announcements/news/";

/**
 * swaps target image source with new image source
 */
function swap( target, newImg ){
	target.src = newImg.src;
} // END - swap()

/**
 * change the windows url location
 */
function goTo( url ){
	window.location = url;
} // END - goTo()

/**
 * changes the display property of an id element to 'block';
 */
function show (target_id){
	if ( !document.getElementById )
		return true;

	var target = document.getElementById(target_id).style;
	
	target.display = "block";

	return false;
} // END - show()

/**
 * changes the display property of an id element to 'hide';
 */
function hide (target_id){
	if ( !document.getElementById )
		return true;
	
	var target = document.getElementById(target_id).style;
	
	target.display = "none";

	return false;
	
} // END - hide()

/**
 * displays the deparment news while changing the tab menu
 */
function  showDeptNews(){
	show('dept_news');
	hide('undergrad_news');
	
	// swap the left tab edges
	swap( document.dept_lt, tab_1_lt_off );
	swap( document.dept_rt, tab_1_rt_off );
	
	// swap the right tab edge
	swap( document.undergrad_rt, tab_2_rt_on );
	
	// change the department button's html code
	document.getElementById('dept_news_button').innerHTML =	'<img src="/images/tab_images/dept_news_off.gif" width="111" height="21" name="dept_img" border="0" />';
		
	// change the undergrad button's html code
	document.getElementById('undergrad_news_button').innerHTML =
		'<a href="javascript:showUndergradNews();" onMouseOver="swap(undergrad_img,undergrad_over);" onMouseOut="swap(undergrad_img,undergrad_out);">' +
		'<img src="/images/tab_images/undergrad_news_on.gif" width="129" height="21" name="undergrad_img" border="0" />' +
		'</a>';
	
	currentLink = "/announcements/news/";
} // END - showDeptNews()

/**
 * displays the undergraduate news while changing the tab menu
 */
function showUndergradNews(){
	show('undergrad_news');
	hide('dept_news');
	
	// swap the left tab edges
	swap( document.dept_lt, tab_1_lt_on );
	swap( document.dept_rt, tab_1_rt_on );
	
	// swap the right tab edge
	swap( document.undergrad_rt, tab_2_rt_off );
	
	// change the department button's html code
	document.getElementById('dept_news_button').innerHTML =
		'<a href="javascript:showDeptNews();" onMouseOver="swap(dept_img,dept_over);" onMouseOut="swap(dept_img,dept_out);">' +
		'<img src="/images/tab_images/dept_news_on.gif" width="111" heigth="21" name="dept_img" border="0" />' +
		'</a>';
		
	// change the undergrad button's html code
	document.getElementById('undergrad_news_button').innerHTML =	'<img src="/images/tab_images/undergrad_news_off.gif" width="129" height="21" name="undergrad_img" border="0" />';
	
	currentLink = "announcements/undergrad_news";
} // END - showUndergradNews()