//   |----------------------------------------------------------
//   | JavaSlideShow by Doug Simmons - Free for all use with    
//   | email notification to the author (jester@orst.edu) upon  
//   | the first usage (comments/suggestions?). Updates are 	
//   | available as released, upon request.							
//   |															
//   | This file contains the engine to the JavaSlideShow.      
//   | Modification are not recommended. Instead suggest		
//   | modifications to the author..							
//   |----------------------------------------------------------

var CurrentSlide = "";
var CurrentShow = "";
var CURRENT_IMAGE = 0;
var CURRENT_TEXT = 1;
var CURRENT_SLIDESHOW_IMAGESET = 0;
var CURRENT_SLIDESHOW_TEXTSET = 1;
var myCurrentSlideShow;
var SlideShowReel;
var Parsed = false;

//used to check if java is available from the client's browser
function JavaIsAvailable()
{
	return ( navigator.javaEnabled() );
}

//used to check if clients browser is netscape
function BrowserIsNetscape()
{
	if( navigator.appName == "Netscape" ) 
		return true;
}

//used to change the image on the page
function ChangeImage(name,file) 
{
		eval('document.images["'+name+'"].src="'+file+'"');
}

//used to construct our SlideShow Arrays.
function buildArray()
{ //Used to contruct an array
	var a = buildArray.arguments;
	for (i=0; i<a.length; i++)
	{
		this[i] = a[i];
	}
	  	this.length = a.length;
}

//parses the search part of the URL - "?show=2&slide=3"
//once parsed it set the global vairables CURRENT_SLIDESHOW_IMAGESET, 
//CURRENT_SLIDESHOW_TEXTSET, CURRENT_IMAGE, and CURRENT_TEXT per the user's request. 
function parseSearchURL ()
{
	var SearchURL = document.location.search;
	var tempstring = "";
	var tempvalue = "";
	var foundEquals = false;
	
	for ( i=0; i < SearchURL.length; i++ )
	{
		if ((SearchURL.charAt(i) != "?") && (SearchURL.charAt(i) != "&") && (i != SearchURL.length - 1))
		{
			if (SearchURL.charAt(i) == "=")
			{
				foundEquals = true;
			}
			else 
			{
				if (! (foundEquals) )
				{
					tempstring = tempstring + SearchURL.charAt(i);
				}				
				else
				{
					tempvalue = tempvalue + SearchURL.charAt(i);
				}
			}
		}
		else
		{
			if (i == SearchURL.length - 1)
			{
				tempvalue = tempvalue + SearchURL.charAt(i);
			}
			
			tempstring = tempstring.toUpperCase();
			tempvalue = tempvalue.toUpperCase();

			if (tempstring == "SHOW") {
				CurrentShow = tempvalue;
			}
			if (tempstring == "SLIDE") {
				CurrentSlide = tempvalue;
			}
			tempstring = "";
			tempvalue = "";
			foundEquals = false;
		}
	}
	if (CurrentShow != "")
	{
		if (( CurrentShow > (SlideShowReel.length / 2)) || ( CurrentShow < 1 ))
		{
			alert("The specified slide show does not exist.\nStarting with the first show in the reel.");
		}
		else 
		{
			CURRENT_SLIDESHOW_IMAGESET = ((CurrentShow * 2) - 2);
			CURRENT_SLIDESHOW_TEXTSET = ((CurrentShow * 2) - 1);
		}
	}
	if (CurrentSlide != "")
	{
		CURRENT_IMAGE = ((CurrentSlide * 2) - 2);
		CURRENT_TEXT = ((CurrentSlide * 2) - 1);
	}
	Parsed = true;
}
 
//initiates the slideshow, loading the Reel, the current show, etc.
//returns the Current Slideshow array. 
function InitSlideShow() 
{
	if (! ( Parsed ) )
		parseSearchURL();  //determine if user has defined a specific show.
	var SlideShowArray = new buildArray();
	var ARRAY_LENGTH = ((SlideShowReel[CURRENT_SLIDESHOW_IMAGESET].length) + (SlideShowReel[CURRENT_SLIDESHOW_TEXTSET].length));
	SlideShowArray.length = ARRAY_LENGTH; 
															 
	if (! (SlideShowReel[CURRENT_SLIDESHOW_IMAGESET].length == SlideShowReel[CURRENT_SLIDESHOW_TEXTSET].length) )
	{
		alert("Error::Number of Images in SlideSet <> Number of Text in SlideSet");
		return "error";
	}
	else										 										 
	{
		j = -1;
		for ( i=0; i < ARRAY_LENGTH - 1; i++)
		{
	  		j = j + 1;
			SlideShowArray[j] = SlideShowReel[CURRENT_SLIDESHOW_IMAGESET][i];
			j = j + 1;
			SlideShowArray[j] = SlideShowReel[CURRENT_SLIDESHOW_TEXTSET][i];
		}
		return SlideShowArray;
	}
}

//Preloads the next image of the current slide show on the reel.
function PreLoadNextImage ()
{
	var Image1 = new Image();

	if (CURRENT_IMAGE > myCurrentSlideShow.length - 2)
		return;	//we have reached the end of our SlideShowArray
	else if (CURRENT_IMAGE != 0)
		Image1.src = myCurrentSlideShow[CURRENT_IMAGE + 2];
	else
		Image1.src = myCurrentSlideShow[CURRENT_IMAGE];
	return; 
}

//Advances the slide show.
function AdvanceSlideShow ()
{	
	if ((CURRENT_TEXT != myCurrentSlideShow.length - 1) && (CURRENT_IMAGE != myCurrentSlideShow.length - 2))
	{
		CURRENT_IMAGE = CURRENT_IMAGE + 2;
		CURRENT_TEXT = CURRENT_TEXT + 2
		ChangeImage("SlideImage", myCurrentSlideShow[CURRENT_IMAGE]);
		if (! BrowserIsNetscape () ) {
			SlideText.innerHTML = myCurrentSlideShow[CURRENT_TEXT];
		}
		else {
			document.SlideText.document.write(myCurrentSlideShow[CURRENT_TEXT]);
			document.SlideText.document.close();
		}

		PreLoadNextImage();
	}	
	else if ((CURRENT_SLIDESHOW_IMAGESET != SlideShowReel.length - 2) && (CURRENT_SLIDESHOW_TEXTSET != SlideShowReel.length - 1))
	{
		CURRENT_SLIDESHOW_IMAGESET = CURRENT_SLIDESHOW_IMAGESET + 2;
		CURRENT_SLIDESHOW_TEXTSET = CURRENT_SLIDESHOW_TEXTSET + 2;
		CURRENT_IMAGE = 0;
		CURRENT_TEXT = 1;
		myCurrentSlideShow = InitSlideShow();
		if (myCurrentSlideShow != "error") {
			ChangeImage("SlideImage", myCurrentSlideShow[CURRENT_IMAGE]);
			if (! BrowserIsNetscape () ) {
				SlideText.innerHTML = myCurrentSlideShow[CURRENT_TEXT];
			}
			else {
				document.SlideText.document.write(myCurrentSlideShow[CURRENT_TEXT]);
				document.SlideText.document.close();
			}
			PreLoadNextImage();
		}
	}
	else
	{
		alert("You have reached the end of the slide reel.");
	}
}

//reverts the slide show to previously viewed slides.
function RevertSlideShow ()
{
	if ((CURRENT_TEXT != 1) && (CURRENT_IMAGE != 0))
	{
		CURRENT_IMAGE = CURRENT_IMAGE - 2;
		CURRENT_TEXT = CURRENT_TEXT - 2;
		ChangeImage("SlideImage", myCurrentSlideShow[CURRENT_IMAGE]);
		if (! BrowserIsNetscape () ) {
			SlideText.innerHTML = myCurrentSlideShow[CURRENT_TEXT];
		}
		else {
			document.SlideText.document.write(myCurrentSlideShow[CURRENT_TEXT]);
			document.SlideText.document.close();
		}
	}
	else if ((CURRENT_SLIDESHOW_TEXTSET !=1 ) && (CURRENT_SLIDESHOW_IMAGESET !=0))
	{
		CURRENT_SLIDESHOW_IMAGESET = CURRENT_SLIDESHOW_IMAGESET - 2;
		CURRENT_SLIDESHOW_TEXTSET = CURRENT_SLIDESHOW_TEXTSET - 2;
		myCurrentSlideShow = InitSlideShow();
		CURRENT_IMAGE = myCurrentSlideShow.length - 2;
		CURRENT_TEXT = myCurrentSlideShow.length - 1;
		if (myCurrentSlideShow != "error") {
			ChangeImage("SlideImage", myCurrentSlideShow[CURRENT_IMAGE]);
			if (! BrowserIsNetscape () ) {
				SlideText.innerHTML = myCurrentSlideShow[CURRENT_TEXT];
			}
			else {
				document.SlideText.document.write(myCurrentSlideShow[CURRENT_TEXT]);
				document.SlideText.document.close();
			}
		}
	}
	else
	{
		alert("You have reached the beginning of the slide reel.");
	}
	
}

//Inserts the Slide Image on the projector page.
function InsertSlideImage ()
{
	if ((CURRENT_IMAGE > myCurrentSlideShow.length - 2) || (CURRENT_IMAGE < 0))
	{
		alert("The specified slide does not exist in this show.\nStarting with the first slide in the show.");
		CURRENT_IMAGE = 0;
		CURRENT_TEXT = 1;
	}		
	document.write("<div align=center><img name=\"SlideImage\" src=\"" + myCurrentSlideShow[CURRENT_IMAGE] + "\" alt=\"SlideImage\"></div>");
}

//Inserts the Slide Text on the projector page.
function InsertSlideText ()
{
   if (! BrowserIsNetscape() ) {
	document.write("<div align=center><span class=normaltext id=\"SlideText\">" + myCurrentSlideShow[CURRENT_TEXT] + "</span></div>" );
   }
   else 
   { 
	 //document.write("<layer id=\"SlideText\">" + myCurrentSlideShow[CURRENT_TEXT] + "</layer>" );
	 document.write("<br>" + myCurrentSlideShow[CURRENT_TEXT] + "<br>");
   }
}

//Inserts the slide buttons onto the slide page... 
//Input required is the image location of the buttons to use.. 
//Note:: it looks for the images "previous.gif" and "next.gif"
function InsertSlideButtons ( image_location )
{
	var showNext = ((CURRENT_SLIDESHOW_IMAGESET + 2) / 2);
	var showPrev = showNext;
	var slideNext = (((CURRENT_IMAGE + 2) / 2) + 1);
	var slidePrev = (((CURRENT_IMAGE + 2) / 2) - 1);

	if ( ( CURRENT_IMAGE == 0) && (CURRENT_SLIDESHOW_IMAGESET != 0) )
	{
		showPrev = showPrev - 1; //decrement show for previous button.
		slidePrev = (SlideShowReel[CURRENT_SLIDESHOW_IMAGESET - 2].length);
	}
	if ( (CURRENT_IMAGE == (myCurrentSlideShow.length - 2)) && (CURRENT_SLIDESHOW_IMAGESET != (myCurrentSlideShow.length - 2)) )
	{
		showNext = showNext + 1; //increment show for next button.
		slideNext = 1;
	}

   document.write("<table border=0 cellpadding=2 cellspacing=2 align=center>");  //start the table that contains the buttons.
   document.write("<tr>");  
   
   if (! BrowserIsNetscape() ) 
   { //Internet Explorer or Other.
			document.write('<td onclick="javascript:RevertSlideShow();" style="cursor:hand;"><img src="' + image_location + 'images/pictures/previous.gif" alt="Previous" width="80" height="30" border="0"></td>');
			document.write('<td onclick="javascript:AdvanceSlideShow();" style="cursor:hand;"><img src="' + image_location + 'images/pictures/next.gif" alt="Next" width="80" height="30" border="0"></td>');
   }
   else 
   { //Netscape.
		if ( (CURRENT_SLIDESHOW_IMAGESET != 0) || (CURRENT_IMAGE != 0) )
			document.write('<td><a href="' + location.pathname + '?show=' + showPrev + '&slide=' + slidePrev + '"><img src="' + image_location + 'images/pictures/previous.gif" alt="Previous" width="80" height="30" border="0"></a></td>');
		if ( (CURRENT_SLIDESHOW_TEXTSET != (SlideShowReel.length - 1)) || (CURRENT_TEXT != (myCurrentSlideShow.length - 1)) )
			document.write('<td><a href="' + location.pathname + '?show=' + showNext + '&slide=' + slideNext + '"><img src="' + image_location + 'images/picturesd/next.gif" alt="Next" width="80" height="30" border="0"></a></td>');
   }
   
   document.write("</tr>");
   document.write("</table>"); //end the table that contains the buttons.
}