/* Copyright (c) 2009 Kelvin Luck (kelvin AT kelvinluck DOT com || http://www.kelvinluck.com)
 * Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php) 
 * and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.
 * 
 * See http://kelvinluck.com/assets/jquery/jScrollPane/
 * $Id: jScrollPane.js 90 2010-01-25 03:52:10Z kelvin.luck $
 */

/**
 *
 * @example jQuery(".scroll-pane").jScrollPane();
 *
 * @name jScrollPane
 * @type jQuery
 * @param Object	settings
 * @return jQuery
 * @cat Plugins/jScrollPane
 * @author Kelvin Luck (kelvin AT kelvinluck DOT com || http://www.kelvinluck.com)
 */

(function($) {

$.jScrollPane = {
	active : []
};
$.fn.jScrollPane = function(settings)
{
	settings = $.extend({}, $.fn.jScrollPane.defaults, settings);

	var rf = function() { return false; };
	
	return this.each(
		function()
		{
			var $this = $(this);
			var paneEle = this;
			var currentScrollPosition = 0;
			var paneWidth;
			var paneHeight;
			var trackHeight;
			var trackOffset = settings.topCapHeight;
			var $container;
			
			$this.parent().parent().find('.scrollbar').mouseenter(function() { $(this).addClass('scrollbar-hover'); }).mouseleave(function() { $(this).removeClass('scrollbar-hover'); }).html('<div class="scrolltrack"><div class="scrollhandle"></div></div><div class="scrollarrows"><a href="#" class="btn-scroll-up">&nbsp;</a><a href="#" class="btn-scroll-down">&nbsp;</a></div>');
			
			
			if ($(this).parent().is('.inner')) {
				$container = $(this).parent();
				currentScrollPosition = settings.maintainPosition ? $this.position().top : 0;
				var $c = $(this).parent();
				paneWidth = $c.innerWidth();
				paneHeight = $c.outerHeight();
				$this.css({'top':0});
				this.originalPadding = 0;
				this.originalSidePaddingTotal = 0;
				$this.data('originalStyleTag', '');
			}
			
			trackHeight = $(this).parent().next().find('.scrolltrack').height();
			
			if (settings.reinitialiseOnImageLoad) {
				var $imagesToLoad = $.data(paneEle, 'jScrollPaneImagesToLoad') || $('img', $this);
				var loadedImages = [];
				
				if ($imagesToLoad.length) {
					$imagesToLoad.each(function(i, val)	{
						$(this).bind('load readystatechange', function() {
							if($.inArray(i, loadedImages) == -1){ //don't double count images
								loadedImages.push(val); //keep a record of images we've seen
								$imagesToLoad = $.grep($imagesToLoad, function(n, i) {
									return n != val;
								});
								$.data(paneEle, 'jScrollPaneImagesToLoad', $imagesToLoad);
								var s2 = $.extend(settings, {reinitialiseOnImageLoad:false});
								$this.jScrollPane(s2); // re-initialise
							}
						}).each(function(i, val) {
							if(this.complete || this.complete===undefined) { 
								//needed for potential cached images
								this.src = this.src; 
							} 
						});
					});
				};
			}

			var p = this.originalSidePaddingTotal;
			var realPaneWidth = paneWidth - settings.scrollbarWidth - settings.scrollbarMargin - p;

			var contentHeight = $this.outerHeight();
			var percentInView = paneHeight / contentHeight;
			
			var isScrollable = percentInView < .99;
			$container.parent()[isScrollable ? 'addClass' : 'removeClass']('scrollbar-active');

			if (isScrollable) {
			
				$this.parent().unbind('mousewheel').unbind('mousedown.jScrollPane').unbind('keydown.jscrollpane').unbind('keyup.jscrollpane');
				
				var $track = $container.next().find('.scrolltrack');
				var $drag = $container.next().find('.scrollhandle');
				
				trackHeight = $track.height();
				
				var currentArrowDirection;
				var currentArrowTimerArr = [];// Array is used to store timers since they can stack up when dealing with keyboard events. This ensures all timers are cleaned up in the end, preventing an acceleration bug.
				var currentArrowInc;
				var whileArrowButtonDown = function() 
				{
					if (currentArrowInc > 4 || currentArrowInc % 4 == 0) {
						positionDrag(dragPosition + currentArrowDirection * mouseWheelMultiplier);
					}
					currentArrowInc++;
				};

				if (settings.showArrows) {
					
					var currentArrowButton;
					var currentArrowInterval;

					var onArrowMouseUp = function(event)
					{
						$('html').unbind('mouseup', onArrowMouseUp);
						currentArrowButton.removeClass('jScrollActiveArrowButton');
						clearInterval(currentArrowInterval);
					};
					var onArrowMouseDown = function() {
						$('html').bind('mouseup', onArrowMouseUp);
						currentArrowButton.addClass('jScrollActiveArrowButton');
						currentArrowInc = 0;
						whileArrowButtonDown();
						currentArrowInterval = setInterval(whileArrowButtonDown, 100);
					};
					
					
					var $upArrow = $track.next().find('.btn-scroll-up');
					var $downArrow = $track.next().find('.btn-scroll-down');
					
					$upArrow
						.bind('mousedown', function()
						{
							currentArrowButton = $(this);
							currentArrowDirection = -1;
							onArrowMouseDown();
							this.blur();
							return false;
						})
						.bind('click', rf);
						
					$downArrow
						.bind('mousedown', function()
						{
							currentArrowButton = $(this);
							currentArrowDirection = 1;
							onArrowMouseDown();
							this.blur();
							return false;
						})
						.bind('click', rf)

				}
				
				var $pane = $(this).css({'position':'absolute', 'overflow':'visible'});
				
				var currentOffset;
				var maxY;
				var mouseWheelMultiplier;
				// store this in a seperate variable so we can keep track more accurately than just updating the css property..
				var dragPosition = 0;
				var dragMiddle = percentInView*paneHeight/2;
				
				// pos function borrowed from tooltip plugin and adapted...
				var getPos = function (event, c) {
					var p = c == 'X' ? 'Left' : 'Top';
					return event['page' + c] || (event['client' + c] + (document.documentElement['scroll' + p] || document.body['scroll' + p])) || 0;
				};
				
				var ignoreNativeDrag = function() {	return false; };
				
				var initDrag = function()
				{
					ceaseAnimation();
					currentOffset = $drag.offset(false);
					currentOffset.top -= dragPosition;
					
					maxY = trackHeight - $drag[0].offsetHeight;
					mouseWheelMultiplier = 2 * settings.wheelSpeed * maxY / contentHeight;
				};
				
				var onStartDrag = function(event)
				{
					initDrag();
					dragMiddle = getPos(event, 'Y') - dragPosition - currentOffset.top;
					$('html').bind('mouseup', onStopDrag).bind('mousemove', updateScroll);
					if ($.browser.msie) {
						$('html').bind('dragstart', ignoreNativeDrag).bind('selectstart', ignoreNativeDrag);
					}
					return false;
				};
				var onStopDrag = function()
				{
					$('html').unbind('mouseup', onStopDrag).unbind('mousemove', updateScroll);
					dragMiddle = percentInView*paneHeight/2;
					if ($.browser.msie) {
						$('html').unbind('dragstart', ignoreNativeDrag).unbind('selectstart', ignoreNativeDrag);
					}
				};
				var positionDrag = function(destY)
				{
					$container.scrollTop(0);
					destY = destY < 0 ? 0 : (destY > maxY ? maxY : destY);
					dragPosition = destY;
					$drag.css({'top':destY+'px'});
					var p = destY / maxY;
					$this.data('jScrollPanePosition', (paneHeight-contentHeight)*-p);
					$pane.css({'top':((paneHeight-contentHeight)*p) + 'px'});
					$this.trigger('scroll');
					if (settings.showArrows) {
						$upArrow[destY == 0 ? 'addClass' : 'removeClass']('disabled');
						$downArrow[destY == maxY ? 'addClass' : 'removeClass']('disabled');
					}
				};
				var updateScroll = function(e)
				{
					positionDrag(getPos(e, 'Y') - currentOffset.top - dragMiddle);
				};
				
				var dragH = Math.max(Math.min(percentInView*(paneHeight-settings.arrowSize*2), settings.dragMaxHeight), settings.dragMinHeight);
				if(dragH > trackHeight) dragH = trackHeight-5;
				
				$drag.css(
					{'height':dragH+'px'}
				).bind('mousedown', onStartDrag);
				
				var trackScrollInterval;
				var trackScrollInc;
				var trackScrollMousePos;
				var doTrackScroll = function()
				{
					if (trackScrollInc > 8 || trackScrollInc%4==0) {
						positionDrag((dragPosition - ((dragPosition - trackScrollMousePos) / 2)));
					}
					trackScrollInc ++;
				};
				var onStopTrackClick = function()
				{
					clearInterval(trackScrollInterval);
					$('html').unbind('mouseup', onStopTrackClick).unbind('mousemove', onTrackMouseMove);
				};
				var onTrackMouseMove = function(event)
				{
					trackScrollMousePos = getPos(event, 'Y') - currentOffset.top - dragMiddle;
				};
				var onTrackClick = function(event)
				{
					initDrag();
					onTrackMouseMove(event);
					trackScrollInc = 0;
					$('html').bind('mouseup', onStopTrackClick).bind('mousemove', onTrackMouseMove);
					trackScrollInterval = setInterval(doTrackScroll, 100);
					doTrackScroll();
					return false;
				};
				
				$track.bind('mousedown', onTrackClick);
				
				$container.bind(
					'mousewheel',
					function (event, delta) {
						delta = delta || (event.wheelDelta ? event.wheelDelta / 120 : (event.detail) ? -event.detail/3 : 0);
						initDrag();
						ceaseAnimation();
						var d = dragPosition;
						positionDrag(dragPosition - delta * mouseWheelMultiplier);
						var dragOccured = (d != dragPosition);
						return !dragOccured;
					}
				);

				var _animateToPosition;
				var _animateToInterval;
				function animateToPosition()
				{
					var diff = (_animateToPosition - dragPosition) / settings.animateStep;
					if (diff > 1 || diff < -1) {
						positionDrag(dragPosition + diff);
					} else {
						positionDrag(_animateToPosition);
						ceaseAnimation();
					}
				}
				var ceaseAnimation = function()
				{
					if (_animateToInterval) {
						clearInterval(_animateToInterval);
						delete _animateToPosition;
					}
				};
				var scrollTo = function(pos, preventAni)
				{
					if (typeof pos == "string") {
						// Legal hash values aren't necessarily legal jQuery selectors so we need to catch any
						// errors from the lookup...
						try {
							$e = $(pos, $this);
						} catch (err) {
							return;
						}
						if (!$e.length) return;
						pos = $e.offset().top - $this.offset().top;
					}
					ceaseAnimation();
					var maxScroll = contentHeight - paneHeight;
					pos = pos > maxScroll ? maxScroll : pos;
					$this.data('jScrollPaneMaxScroll', maxScroll);
					var destDragPosition = pos/maxScroll * maxY;
					if (preventAni || !settings.animateTo) {
						positionDrag(destDragPosition);
					} else {
						$container.scrollTop(0);
						_animateToPosition = destDragPosition;
						_animateToInterval = setInterval(animateToPosition, settings.animateInterval);
					}
				};
				$this[0].scrollTo = scrollTo;
				
				$this[0].scrollBy = function(delta)
				{
					var currentPos = -parseInt($pane.css('top')) || 0;
					scrollTo(currentPos + delta);
				};
				
				initDrag();
				
				scrollTo(-currentScrollPosition, true);
			
				// Deal with it when the user tabs to a link or form element within this scrollpane
				$('*', this).bind(
					'focus',
					function(event)
					{
						var $e = $(this);
						
						// loop through parents adding the offset top of any elements that are relatively positioned between
						// the focused element and the jScrollPaneContainer so we can get the true distance from the top
						// of the focused element to the top of the scrollpane...
						var eleTop = 0;
						
						while ($e[0] != $this[0]) {
							eleTop += $e.position().top;
							$e = $e.offsetParent();
						}
						
						var viewportTop = -parseInt($pane.css('top')) || 0;
						var maxVisibleEleTop = viewportTop + paneHeight;
						var eleInView = eleTop > viewportTop && eleTop < maxVisibleEleTop;
						if (!eleInView) {
							var destPos = eleTop - settings.scrollbarMargin;
							if (eleTop > viewportTop) { // element is below viewport - scroll so it is at bottom.
								destPos += $(this).height() + 15 + settings.scrollbarMargin - paneHeight;
							}
							scrollTo(destPos);
						}
					}
				)
				
				
				// Deal with dragging and selecting text to make the scrollpane scroll...
				function onSelectScrollMouseDown(e)
				{
				   $(document).bind('mousemove.jScrollPaneDragging', onTextSelectionScrollMouseMove);
				   $(document).bind('mouseup.jScrollPaneDragging',   onSelectScrollMouseUp);
				  
				}
				
				var textDragDistanceAway;
				var textSelectionInterval;
				
				function onTextSelectionInterval()
				{
					direction = textDragDistanceAway < 0 ? -1 : 1;
					$this[0].scrollBy(textDragDistanceAway / 2);
				}

				function clearTextSelectionInterval()
				{
					if (textSelectionInterval) {
						clearInterval(textSelectionInterval);
						textSelectionInterval = undefined;
					}
				}
				
				function onTextSelectionScrollMouseMove(e)
				{
					var offset = $this.parent().offset().top;
					var maxOffset = offset + paneHeight;
					var mouseOffset = getPos(e, 'Y');
					textDragDistanceAway = mouseOffset < offset ? mouseOffset - offset : (mouseOffset > maxOffset ? mouseOffset - maxOffset : 0);
					if (textDragDistanceAway == 0) {
						clearTextSelectionInterval();
					} else {
						if (!textSelectionInterval) {
							textSelectionInterval  = setInterval(onTextSelectionInterval, 100);
						}
					}
				}

				function onSelectScrollMouseUp(e)
				{
				   $(document)
					  .unbind('mousemove.jScrollPaneDragging')
					  .unbind('mouseup.jScrollPaneDragging');
				   clearTextSelectionInterval();
				}

				$container.bind('mousedown.jScrollPane', onSelectScrollMouseDown);

				
				$.jScrollPane.active.push($this[0]);
				
			} else {
				
				$this[0].scrollTo = $this[0].scrollBy = function() {};
				// clean up listeners
				$this.parent().unbind('mousewheel').unbind('mousedown.jScrollPane').unbind('keydown.jscrollpane').unbind('keyup.jscrollpane');
				
			}
			
		}
	)
};

$.fn.jScrollPaneRemove = function()
{
	$(this).each(function()
	{
		$this = $(this);
		var $c = $this.parent();
		if ($c.is('.jScrollPaneContainer')) {
			$this.css(
				{
					'top':'',
					'height':'',
					'width':'',
					'padding':'',
					'overflow':'',
					'position':''
				}
			);
			$this.attr('style', $this.data('originalStyleTag'));
			$c.after($this).remove();
		}
	});
}

$.fn.jScrollPane.defaults = {
	scrollbarWidth : 10,
	scrollbarMargin : 5,
	wheelSpeed : 10,
	showArrows : true,
	arrowSize : 0,
	animateTo : false,
	dragMinHeight : 48,
	dragMaxHeight : 99999,
	animateInterval : 10,
	animateStep: 3,
	maintainPosition: true,
	scrollbarOnLeft: false,
	reinitialiseOnImageLoad: false,
	tabIndex : 0,
	enableKeyboardNavigation: false,
	animateToInternalLinks: false,
	topCapHeight: 0,
	bottomCapHeight: 0,
	observeHash: false
};

// clean up the scrollTo expandos
$(window)
	.bind('unload', function() {
		var els = $.jScrollPane.active; 
		for (var i=0; i<els.length; i++) {
			els[i].scrollTo = els[i].scrollBy = null;
		}
	}
);

})(jQuery);