// JavaScript Document

var isDOM = (document.getElementById ? true : false);
var isIE4 = ((document.all && !isDOM) ? true : false);
var isNS4 = (document.layers ? true : false);
var isDyn = (isDOM || isIE4 || isNS4);

function getRef(id) {
	if (isDOM) return document.getElementById(id);
	if (isIE4) return document.all[id];
	if (isNS4) return document.layers[id];
}

function getSty(id) {
	return (isNS4 ? getRef(id) : getRef(id).style);
}


// *** LOAD FILES INTO DIV FUNCTIONS ***

function scrLoad(name) { with (this) {
	if (!name) return;

	// If you feel like extending this code a bit in an easy way, why not copy-and-paste the
	// visibility settings from the end of scrFileLoaded() to here... but hide the scroller and
	// show the loading message for a while? Just a thought...

	// The location of this file, used as a starting point for all relative files
	// e.g. loadFile('downloads/index.html').
	var path = location.href.substring(0, location.href.lastIndexOf('/') + 1);

	if (isDOM || isIE4) {
		// The document currently loaded into the buffer.
		oldLoc = bufRef.location.href;
		
		// If we haven't been given a full URL with a protocol, add the path to this point.
		if ((name.substring(0, 5) != 'http:') && (name.substring(0, 5) != 'file:'))
		name = path + name;
		
		// This is a kludge, since NS6 doesn't support Iframe onloads yet. Give it 5 secs to load.
		if (isDOM && !document.all) setTimeout(myName + '.bufRef.document.readyState="complete"', 5000);

		if (oldLoc != name) {
			// If we're not reloading the same file, set frame location and start checking routine.
			bufRef.location.href = name;
			checkBuffer(oldLoc);
		}
		// Else if we're reloading the same file, just pass a dummy old location so routine
		// will presume the new one is different and load immediately.
		else checkBuffer('dummyLocation');
	}
	else {
		// Once done, display it and scroll to top.
		divRef.onload = new Function(myName + '.fileLoaded()');
		// Netscape's load(URL, width) method...
		divRef.load(name, cWidth);
	}
}}

function scrCheckBuffer(oldLoc) { with (this) {
	// If the frame hasn't started loading a new file or hasn't finished, recheck in 50ms.
	if ((bufRef.location.href == oldLoc) || (bufRef.document.readyState != 'complete'))
		setTimeout(myName + '.checkBuffer(\'' + oldLoc + '\')', 50);
	else {
		// Transfer frame's content to the div.
		divRef.innerHTML = bufRef.document.body.innerHTML;
		// Remove file from buffer, to allow refreshing - not strictly necessary.
		bufRef.location.href = 'about:blank';
		// That's it, we're done! The timeout helps IE4 giving it a chance to calculate div height.
		setTimeout(myName + '.fileLoaded()', 1);
	}
}}

function scrFileLoaded() { with (this) {
	// Stop dragging any scroller while we switch files.
	activeScr = null;

	// Back to top...
	scrollBy(-100000);

	// And set visibilities now everything's finally ready.
//	loadSty.visibility = 'hidden';
	for (count = 0; count < divs.length; count++)
		getSty(divs[count][0]).visibility = 'visible';
}}


// *** DIV SCROLLING FUNCTION ***

function scrScrollBy(amount) { with (this) {
	if (!isDyn || !loaded) return;

	// Because this gets passed fractions sometimes.
	amount = parseInt(amount);

	// Height of div - update here as it may change often. Find it out somehow :).
	divHeight = document.all ? divRef.clientHeight : (isDOM ? divRef.offsetHeight : divRef.document.height);
	// Stops 'divide by zero'
	if (divHeight == 0) divHeight = 1;

	// Are we scrolling out of range? If so, return to top/bottom.
	if ((cBot + amount) > divHeight) amount = divHeight - cBot;
	if ((cTop + amount) < 0) amount = 0 - cTop;

	// Adjust clipping values & move div up/down... 'scrolling' div.
	cTop += amount;
	cBot += amount;
	if (isDOM || isIE4)
		divSty.clip = 'rect(' + cTop + 'px ' + cWidth + 'px ' + cBot + 'px ' + 0 + 'px)';
	else if (isNS4) {
		// NS4 bug fix, seems to be required, as sometimes these get undefined... why?
		// I think it's because one onMouseMove gets called before another finishes, and somehow
		// NS4 must lose track of its variables.
		if (isNaN(cTop) || isNaN(cBot) || isNaN(amount)) layout();
		
		// Order of adjustment matters, cannot overlap opposing clips.
		if (cBot < divSty.clip.top) divSty.clip.top = cTop;
		divSty.clip.bottom = cBot;
		divSty.clip.top = cTop;
	}

	divSty.top = eval(divs[0][2]) - cTop;

	// Define its height as the percentage of the clipping height vs div height.
	// Best to set it here as divHeight may change as images load etc.
	thmHeight = Math.ceil(barHeight * ((cBot - cTop) / divHeight));

	// Minimum and maximum heights for thumb...
	if (thmHeight < minThmHeight) thmHeight = minThmHeight;
	if (thmHeight > barHeight) thmHeight = barHeight;

	if (isDOM || isIE4) thmSty.height = thmHeight;
	else if (isNS4) thmSty.clip.height = thmHeight;

	// Adjust scrollbar thumb position only if we're not already dragging it.
	if (activeScr) return;

	// What fraction is the div of its total scrolling range? 0=top, 1=bottom.
	fracDivDown = (cTop / (divHeight - (cBot - cTop)));
	// Now, multiply that by the available space to move and assign its top.
	thmSty.top = parseInt(barSty.top) + fracDivDown * (barHeight - thmHeight);

	// If we're looping, set a timeout to scroll by amount again.
	if (loop) setTimeout(myName + '.scrollBy(' + amount + ')', loop);
}}


// *** SCROLL THUMB DRAGGING EVENT HANDLERS ***

function scrThumbDown(evt) {
	// Set a variable pointing to the active scroller - this scroller object.
	activeScr = this;

	// Offset of mouse cursor within the scrollbar by browser, first IE then NS 6 then 4...
	if (document.all) scrOffset = event.offsetY;
	else scrOffset = evt.layerY;
	return false;
}

function scrThumbMove(evt) {
	if (isNS4) document.routeEvent(evt);

	// Either return true if no scroller is being dragged (so selections work), or...
	if (!activeScr) return true;
	else { with (activeScr) {
		// Workaround for error in NS...
		if (isNaN(cTop) || isNaN(cBot)) divLayout();
		
		// If it's not scrollable, quit.
		if ((cBot > divHeight) || (thmHeight == barHeight)) return;
		
		if (document.all) newTop = document.body.scrollTop + event.clientY - scrOffset;
		else newTop = evt.pageY - scrOffset;
		
		// Test if the thumb is out of range, if so, bring it back, then assign its position.
		var barTop = parseInt(barSty.top);
		if (newTop < barTop) newTop = barTop;
		if (newTop + thmHeight > (barTop + barHeight))
		newTop = (barTop + barHeight) - thmHeight;
		thmSty.top = newTop;
		
		// Fractions of total range moved by the div and scrollbar...
		fracDivDown = cTop / (divHeight - (cBot - cTop));
		fracBarDown = (newTop - barTop) / (barHeight - thmHeight);
		
		// ... then scroll by the required difference to make up.
		scrollBy((fracBarDown - fracDivDown) * (divHeight - (cBot - cTop)));
		
		return false;
	}}
}

function scrThumbUp(evt) {
	if (isNS4) document.routeEvent(evt);
	activeScr = null;
}


// *** SCROLLBAR BACKGROUND CLICK EVENT HANDLER ***

function scrBarClick(evt) { with (this) {
	if (isNS4) document.routeEvent(evt);

	if (document.all) clickPos = document.body.scrollTop + event.clientY;
	else clickPos = evt.pageY;

	// Page up, or page down?
	if (clickPos < parseInt(thmSty.top)) scrollBy(cTop - cBot);
	if (clickPos > (parseInt(thmSty.top) + thmHeight)) scrollBy(cBot - cTop);
}}


// *** LAYOUT HANDLER FOR WINDOW RESIZE ETC ***

function scrLayout() { with (this) {
	if (!isDyn) return;

	winWidth = document.all ? document.body.clientWidth : window.innerWidth;
	winHeight = document.all ? document.body.clientHeight : window.innerHeight;

	if (isNS4 && (scrFirstWidth != winWidth)) {
		// Sorry folks, NS4 has major bugs resizing horizontally and must refresh...
		fileName = location.href;
		if (fileName.indexOf('?') != -1) fileName = fileName.substring(0, fileName.indexOf('?'));
		location.href = fileName + '?loadFile=' + divRef.src;
	}

	// If it's not yet initialised, go no further.
	if (!loaded) return;

	// Minimum values for window sizes.
	if (winWidth < minWinWidth) winWidth = minWinWidth;
	if (winHeight < minWinHeight) winHeight = minWinHeight;

	// Loop through divs array, positioning/sizing controls.
	for (count = 0; count < divs.length; count++) {
		var tmpObj = getSty(divs[count][0]);
		if (divs[count][1]) tmpObj.left = eval(divs[count][1]);
		if (divs[count][2]) tmpObj.top = eval(divs[count][2]);
		if (divs[count][3]) {
			var tmpW = eval(divs[count][3]);
			isNS4 ? tmpObj.clip.width = tmpW : tmpObj.width = tmpW;
		}
		// Don't set the height of the first scrolling div, we have to pick this up later.
		if (divs[count][4] && count != 0) {
			var tmpH = eval(divs[count][4]);
			isNS4 ? tmpObj.clip.height = tmpH : tmpObj.height = tmpH;
		}
	}

	// Set the top, bottom & width clip variables.
	if ((isDOM || isIE4) && !cTop) cTop = 0;
	// This will fix 'undefined' errors in NS.
	if (isNS4) cTop = divSty.clip.top;

	// Bar height and clipping parameters, stored here as accessed often. Set width on-the-fly.
	barHeight = eval(divs[1][4]);
	cBot = cTop + eval(divs[0][4]);
	cWidth = eval(divs[0][3]);
	if (isDOM || isIE4) divSty.width = cWidth;

	// Now, display it using updated variables...
	scrollBy(0);
}}


// *** ON LOAD: CAPTURE EVENTS & MISC. SETUP ***

function scrSetup(defaultFile) { with (this) {
	if (!isDyn) return;

	// References to document objects' properties, stored in scroller object.
	divRef = getRef(divs[0][0]);
	divSty = getSty(divs[0][0]);
	barSty = getSty(divs[1][0]);
	thmSty = getSty(divs[2][0]);
	// Convert these ID's to references now document has loaded.
//	loadSty = getSty(loadSty);
	// NS6 has troubles with the frames array and iframes, so use a workaround.
	bufRef = eval('window.' + bufRef);

	// Other variables - references to bar and thumb divs, only used locally.
	barRef = getRef(divs[1][0]);
	thmRef = getRef(divs[2][0]);

	if (isNS4) {
		barRef.captureEvents(Event.CLICK);
		thmRef.captureEvents(Event.MOUSEDOWN);
		document.captureEvents(Event.MOUSEMOVE | Event.MOUSEUP);
	}

	// Pass events to specific scrollers.
	barRef.onclick = new Function('evt', 'return ' + myName + '.barClick(evt)');
	thmRef.onmousedown = new Function('evt', 'return ' + myName + '.thumbDown(evt)');
	// The mouseMove and mouseUp events are global.
	document.onmousemove = scrThumbMove;
	document.onmouseup = scrThumbUp;

	// For IE4+/NS6, create a new function that stops selections being made when dragging.
	if (document.all) document.onselectstart = new Function('if (activeScr) return false');
	else if (isDOM) document.onselect = new Function('if (activeScr) return false');

	// It's now ready to go, call resize function to set the positions and variables...
	loaded = true;
	layout();

	// Get the name of the file to be loaded from a CGI query string...
	fileName = '';
	if (location.href.indexOf('?') != -1)
		fileName = location.href.substring(location.href.lastIndexOf('=') + 1);

	// Contains string '.htm'...? (can be '.html' file of course)
	if (fileName.indexOf('.htm') != -1) load(fileName)

	// Else load default file (if we're passed one) or scroll existing content without loading.
	else if (defaultFile) load(defaultFile);
	else fileLoaded();
}}


// Main object of which instances are created.
function DHTMLScroller(myName, bufferID, loadMess) {
	// Some references to objects that are referred to repeatedly for speed.
	this.divRef = null;
	this.divSty = null;
	this.barSty = null;
	this.thmSty = null;

	// Array of objects to move when the window is resized (e.g. scrollbar, arrows).
	this.divs = new Array();

	// Store the ID's of these objects here for now. Convert to references later...
//	this.loadSty = loadMess;
	this.bufRef = bufferID;

	// Properties.
	this.myName = myName;
	this.loaded = false;
	// A non-zero value for loop will cause a scrollBy call to repeat after that many milliseconds.
	this.loop = 0;
	// Minimum height of scrollbar thumb - defaults to 20, set to something else if you want.
	this.minThmHeight = 20;

	this.divHeight = 0;
	this.barHeight = 0;
	this.thmHeight = 0;
	this.cTop = 0;
	this.cBot = 0;
	this.cWidth = 0;

	// Methods - bind to functions above.
//	this.load = scrLoad;
	this.checkBuffer = scrCheckBuffer;
	this.fileLoaded = scrFileLoaded;
	this.scrollBy = scrScrollBy;
	this.thumbDown = scrThumbDown;
	this.barClick = scrBarClick;
	this.setup = scrSetup;
	this.layout = scrLayout;
}


// *** GLOBAL VARIABLES - START EDITING HERE ***

// Some global variables for the scroller code - scrFirstWidth is only for NS4 resize bug.
var activeScr = null, scrOffset = 0, winWidth, winHeight, scrFirstWidth = window.innerWidth;

// You must declare all scrollers, timeouts as global variables as well.
var mainDiv;

// Minimum window sizes - script will use these if actual sizes are too low.
var minWinWidth = 500, minWinHeight = 300;

// *** SCROLLER OBJECT SETUP ***.

// name = new DHTMLScroller('name', 'iframe buffer id', 'loading message id');
mainDiv = new DHTMLScroller('mainDiv', 'bufferFrame', 'loadMess');