/* Copyright (c) 2006 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 78 2009-07-03 19:16:36Z kelvin.luck@gmail.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;

			if ($(this).parent().is('.jScrollPaneContainer')) {
				var currentScrollPosition = settings.maintainPosition ? $this.position().top : 0;
				var $c = $(this).parent();
				var paneWidth = $c.innerWidth();
				var paneHeight = $c.outerHeight();
				var trackHeight = paneHeight;
				$('>.jScrollPaneTrack, >.jScrollArrowUp, >.jScrollArrowDown', $c).remove();
				$this.css({'top':0});
			} else {
				$this.data('originalStyleTag', $this.attr('style'));
				// Switch the element's overflow to hidden to ensure we get the size of the element without the scrollbars [http://plugins.jquery.com/node/1208]
				$this.css('overflow', 'hidden');
				var currentScrollPosition = 0;
				this.originalPadding = $this.css('paddingTop') + ' ' + $this.css('paddingRight') + ' ' + $this.css('paddingBottom') + ' ' + $this.css('paddingLeft');
				this.originalSidePaddingTotal = (parseInt($this.css('paddingLeft')) || 0) + (parseInt($this.css('paddingRight')) || 0);
				var paneWidth = $this.innerWidth();
				var paneHeight = $this.innerHeight();
				var trackHeight = paneHeight;
				var $container = $('<div></div>')
					.attr({'className':'jScrollPaneContainer'})
					.css(
						{
							'height':paneHeight+'px',
							'width':paneWidth+'px'
						}
					);
				if (settings.enableKeyboardNavigation) {
					$container.attr(
						'tabindex',
						settings.tabIndex
					);
				}
				$this.wrap($container);
				$(document).bind(
					'emchange',
					function(e, cur, prev)
					{
						$this.jScrollPane(settings);
					}
				);

			}

			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 cssToApply = {
				'height':'auto',
				'width': realPaneWidth + 'px'
			}

			if(settings.scrollbarOnLeft) {
				cssToApply.paddingLeft = settings.scrollbarMargin + settings.scrollbarWidth + 'px';
			} else {
				cssToApply.paddingRight = settings.scrollbarMargin + 'px';
			}

			$this.css(cssToApply);

			var contentHeight = $this.outerHeight();
			var percentInView = paneHeight / contentHeight;

			if (percentInView < .99) {
				var $container = $this.parent();
				$container.append(
					$('<div></div>').attr({'className':'jScrollPaneTrack'}).css({'width':settings.scrollbarWidth+'px'}).append(
						$('<div></div>').attr({'className':'jScrollPaneDrag'}).css({'width':settings.scrollbarWidth+'px'}).append(
							$('<div></div>').attr({'className':'jScrollPaneDragTop'}).css({'width':settings.scrollbarWidth+'px'}),
							$('<div></div>').attr({'className':'jScrollPaneDragBottom'}).css({'width':settings.scrollbarWidth+'px'})
						)
					)
				);

				var $track = $('>.jScrollPaneTrack', $container);
				var $drag = $('>.jScrollPaneTrack .jScrollPaneDrag', $container);


				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.enableKeyboardNavigation) {
					$container.bind(
						'keydown.jscrollpane',
						function(e)
						{
							switch (e.keyCode) {
								case 38: //up
									currentArrowDirection = -1;
									currentArrowInc = 0;
									whileArrowButtonDown();
									currentArrowTimerArr[currentArrowTimerArr.length] = setInterval(whileArrowButtonDown, 100);
									return false;
								case 40: //down
									currentArrowDirection = 1;
									currentArrowInc = 0;
									whileArrowButtonDown();
									currentArrowTimerArr[currentArrowTimerArr.length] = setInterval(whileArrowButtonDown, 100);
									return false;
								case 33: // page up
								case 34: // page down
									// TODO
									return false;
								default:
							}
						}
					).bind(
						'keyup.jscrollpane',
						function(e)
						{
							if (e.keyCode == 38 || e.keyCode == 40) {
								for (var i = 0; i < currentArrowTimerArr.length; i++) {
									clearInterval(currentArrowTimerArr[i]);
								}
								return false;
							}
						}
					);
				}

				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);
					};
					$container
						.append(
							$('<a></a>')
								.attr({'href':'javascript:;', 'className':'jScrollArrowUp', 'tabindex':-1})
								.css({'width':settings.scrollbarWidth+'px'})
								.html('Scroll up')
								.bind('mousedown', function()
								{
									currentArrowButton = $(this);
									currentArrowDirection = -1;
									onArrowMouseDown();
									this.blur();
									return false;
								})
								.bind('click', rf),
							$('<a></a>')
								.attr({'href':'javascript:;', 'className':'jScrollArrowDown', 'tabindex':-1})
								.css({'width':settings.scrollbarWidth+'px'})
								.html('Scroll down')
								.bind('mousedown', function()
								{
									currentArrowButton = $(this);
									currentArrowDirection = 1;
									onArrowMouseDown();
									this.blur();
									return false;
								})
								.bind('click', rf)
						);
					var $upArrow = $('>.jScrollArrowUp', $container);
					var $downArrow = $('>.jScrollArrowDown', $container);
					if (settings.arrowSize) {
						trackHeight = paneHeight - settings.arrowSize - settings.arrowSize;
						$track
							.css({'height': trackHeight+'px', top:settings.arrowSize+'px'})
					} else {
						var topArrowHeight = $upArrow.height();
						settings.arrowSize = topArrowHeight;
						trackHeight = paneHeight - topArrowHeight - $downArrow.height();
						$track
							.css({'height': trackHeight+'px', top:topArrowHeight+'px'})
					}
				}

				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)
				{
					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);

				$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") {
						$e = $(pos, $this);
						if (!$e.length) return;
						pos = $e.offset().top - $this.offset().top;
					}
					$container.scrollTop(0);
					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 {
						_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);

				$('*', this).bind(
					'focus',
					function(event)
					{
						var $e = $(this);

						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);
						}
					}
				)


				if (location.hash) {
					setTimeout(function() {scrollTo(location.hash);}, $.browser.safari ? 100 : 0);
				}

				$(document).bind(
					'click',
					function(e)
					{
						$target = $(e.target);
						if ($target.is('a')) {
							var h = $target.attr('href');
							if (h && h.substr(0, 1) == '#' && h.length > 1) {
								setTimeout(function() {scrollTo(h, !settings.animateToInternalLinks);}, $.browser.safari ? 100 : 0);
							}
						}
					}
				);

				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.css(
					{
						'height':paneHeight+'px',
						'width':paneWidth-this.originalSidePaddingTotal+'px',
						'padding':this.originalPadding
					}
				);
				$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 : 98,
	showArrows : false,
	arrowSize : 0,
	animateTo : false,
	dragMinHeight : 1,
	dragMaxHeight : 99999,
	animateInterval : 100,
	animateStep: 5,
	maintainPosition: true,
	scrollbarOnLeft: false,
	reinitialiseOnImageLoad: false,
	tabIndex : 0,
	enableKeyboardNavigation: true,
	animateToInternalLinks: 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);