/* 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 4702 2008-02-09 10:19:47Z kelvin.luck $
 */

/**
 * Replace the vertical scroll bars on any matched elements with a fancy
 * styleable (via CSS) version. With JS disabled the elements will
 * gracefully degrade to the browsers own implementation of overflow:auto.
 * If the mousewheel plugin has been included on the page then the scrollable areas will also
 * respond to the mouse wheel.
 *
 * @example jQuery(".scroll-pane").jScrollPane();
 *
 * @name jScrollPane
 * @type jQuery
 * @param Object    settings    hash with options, described below.
 *                                scrollbarWidth    -    The width of the generated scrollbar in pixels
 *                                scrollbarMargin    -    The amount of space to leave on the side of the scrollbar in pixels
 *                                wheelSpeed        -    The speed the pane will scroll in response to the mouse wheel in pixels
 *                                showArrows        -    Whether to display arrows for the user to scroll with
 *                                arrowSize        -    The height of the arrow buttons if showArrows=true
 *                                animateTo        -    Whether to animate when calling scrollTo and scrollBy
 *                                dragMinHeight    -    The minimum height to allow the drag bar to be
 *                                dragMaxHeight    -    The maximum height to allow the drag bar to be
 *                                animateInterval    -    The interval in milliseconds to update an animating scrollPane (default 100)
 *                                animateStep        -    The amount to divide the remaining scroll distance by when animating (default 3)
 *                                maintainPosition-    Whether you want the contents of the scroll pane to maintain it's position when you re-initialise it - so it doesn't scroll as you add more content (default true)
 *                                scrollbarOnLeft    -    Display the scrollbar on the left side?  (needs stylesheet changes, see examples.html)
 * @return jQuery
 * @cat Plugins/jScrollPane
 * @author Kelvin Luck (kelvin AT kelvinluck DOT com || http://www.kelvinluck.com)
 */
jQuery.jScrollPane = {
    active : []
};
jQuery.fn.jScrollPane = function(settings)
{
    settings = jQuery.extend(
        {
            scrollbarWidth : 10,
            scrollbarMargin : 0,
            wheelSpeed : 18,
            showArrows : false,
            arrowSize : 0,
            animateTo : false,
            dragMinHeight : 1,
            dragMaxHeight : 99999,
            animateInterval : 100,
            animateStep: 3,
            maintainPosition: true,
            scrollbarOnLeft: false
        }, settings
    );
    return this.each(
        function()
        {
            var $this = jQuery(this);
            
            if (jQuery(this).parent().is('.jScrollPaneContainer')) {
                var currentScrollPosition = settings.maintainPosition ? $this.offset({relativeTo:jQuery(this).parent()[0]}).top : 0;
                var $c = jQuery(this).parent();
                var paneWidth = $c.innerWidth();
                var paneHeight = $c.outerHeight();
                var trackHeight = paneHeight;
                if ($c.unmousewheel) {
                    $c.unmousewheel();
                }
                jQuery('>.jScrollPaneTrack, >.jScrollArrowUp, >.jScrollArrowDown', $c).remove();
                $this.css({'top':0});
            } else {
                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(); //modify
                var borderLeft = (/[0-9]+/).test( $this.parent().css("borderLeftWidth") )
                                        ? parseInt($this.parent().css("borderLeftWidth"))
                                        : 0
                var borderRight = (/[0-9]+/).test( $this.parent().css("borderRightWidth") )
                                        ? parseInt($this.parent().css("borderRightWidth"))
                                        : 0

                var offsetX = settings.scrollbarOnLeft ? borderLeft : borderRight;
                var paneWidth = $this.parent().innerWidth() + offsetX; //+offsetX because always overlaps right border or left border(left is rarely and need change in offsetX)
                var paneHeight = $this.innerHeight();
                var trackHeight = paneHeight;
                $this.wrap(
                    jQuery('<div></div>').attr(
                        {'className':'jScrollPaneContainer'}
                    ).css(
                        {
                            'height':paneHeight+'px', 
                            'width':paneWidth+'px'
                        }
                    )
                );
                // deal with text size changes (if the jquery.em plugin is included)
                // and re-initialise the scrollPane so the track maintains the
                // correct size
                jQuery(document).bind(
                    'emchange', 
                    function(e, cur, prev)
                    {
                        $this.jScrollPane(settings);
                    }
                );
            }
            var p = this.originalSidePaddingTotal;
            
            var cssToApply = {
                'height':'auto',
                'width':paneWidth - settings.scrollbarWidth - settings.scrollbarMargin - p + '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(
                    jQuery('<div></div>').attr({'className':'jScrollPaneTrack'}).css({'width':settings.scrollbarWidth+'px'}).append(
                        jQuery('<div></div>').attr({'className':'jScrollPaneDrag'}).css({'width':settings.scrollbarWidth+'px'}).append(
                            jQuery('<div></div>').attr({'className':'jScrollPaneDragTop'}).css({'width':settings.scrollbarWidth+'px'}),
                            jQuery('<div></div>').attr({'className':'jScrollPaneDragBottom'}).css({'width':settings.scrollbarWidth+'px'})
                        )
                    )
                );
   
                //substract border if Yes: modify
                var borderLeft = typeof jQuery('.jScrollPaneDrag').css("borderLeftWidth") == "number"
                                        ? parseInt(jQuery('.jScrollPaneDrag').css("borderLeftWidth"))
                                        : 0;
                var borderRight = typeof jQuery('.jScrollPaneDrag').css("borderRightWidth") == "number"
                                        ? parseInt(jQuery('.jScrollPaneDrag').css("borderRightWidth"))
                                        : 0;

                jQuery('.jScrollPaneDrag').css({
                    'width': parseInt(jQuery('.jScrollPaneDrag').width()) - borderLeft - borderRight + 'px'
                });
                var $track = jQuery('>.jScrollPaneTrack', $container);
                var $drag = jQuery('>.jScrollPaneTrack .jScrollPaneDrag', $container);
                
                if (settings.showArrows) {
                    
                    var currentArrowButton;
                    var currentArrowDirection;
                    var currentArrowInterval;
                    var currentArrowInc;
                    var whileArrowButtonDown = function()
                    {
                        if (currentArrowInc > 4 || currentArrowInc%4==0) {
                            positionDrag(dragPosition + currentArrowDirection * mouseWheelMultiplier);
                        }
                        currentArrowInc ++;
                    };
                    var onArrowMouseUp = function(event)
                    {
                        jQuery('html').unbind('mouseup', onArrowMouseUp);
                        currentArrowButton.removeClass('jScrollActiveArrowButton');
                        clearInterval(currentArrowInterval);
                        //console.log($(event.target));
                        //currentArrowButton.parent().removeClass('jScrollArrowUpClicked jScrollArrowDownClicked');
                    };
                    var onArrowMouseDown = function() {
                        //console.log(direction);
                        //currentArrowButton = $(this);
                        jQuery('html').bind('mouseup', onArrowMouseUp);
                        currentArrowButton.addClass('jScrollActiveArrowButton');
                        currentArrowInc = 0;
                        whileArrowButtonDown();
                        currentArrowInterval = setInterval(whileArrowButtonDown, 100);
                    };
                    $container
                        .append(
                            jQuery('<a></a>')
                                .attr({'href':'javascript:;', 'className':'jScrollArrowUp'})
                                .css({'width':settings.scrollbarWidth+'px'})
                                .html('Scroll up')
                                .bind('mousedown', function()
                                {
                                    currentArrowButton = jQuery(this);
                                    currentArrowDirection = -1;
                                    onArrowMouseDown();
                                    this.blur();
                                    return false;
                                }),
                            jQuery('<a></a>')
                                .attr({'href':'javascript:;', 'className':'jScrollArrowDown'})
                                .css({'width':settings.scrollbarWidth+'px'})
                                .html('Scroll down')
                                .bind('mousedown', function()
                                {
                                    currentArrowButton = jQuery(this);
                                    currentArrowDirection = 1;
                                    onArrowMouseDown();
                                    this.blur();
                                    return false;
                                })
                        );
                    var $upArrow = jQuery('>.jScrollArrowUp', $container);
                    var $downArrow = jQuery('>.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 = jQuery(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;
                    jQuery('html').bind('mouseup', onStopDrag).bind('mousemove', updateScroll);
                    if (jQuery.browser.msie) {
                        jQuery('html').bind('dragstart', ignoreNativeDrag).bind('selectstart', ignoreNativeDrag);
                    }
                    return false;
                };
                var onStopDrag = function()
                {
                    jQuery('html').unbind('mouseup', onStopDrag).unbind('mousemove', updateScroll);
                    dragMiddle = percentInView*paneHeight/2;
                    if (jQuery.browser.msie) {
                        jQuery('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;
                    $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);
                    jQuery('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;
                    jQuery('html').bind('mouseup', onStopTrackClick).bind('mousemove', onTrackMouseMove);
                    trackScrollInterval = setInterval(doTrackScroll, 100);
                    doTrackScroll();
                };
                
                $track.bind('mousedown', onTrackClick);
                
                // if the mousewheel plugin has been included then also react to the mousewheel
                if ($container.mousewheel) {
                    $container.mousewheel(
                        function (event, delta) {
                            initDrag();
                            ceaseAnimation();
                            var d = dragPosition;
                            positionDrag(dragPosition - delta * mouseWheelMultiplier);
                            var dragOccured = d != dragPosition;
                            return !dragOccured;
                        },
                        false
                    );                    
                }
                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") {
                        $e = jQuery(pos, this);
                        if (!$e.length) return;
                        pos = $e.offset().top - $this.offset().top;
                    }
                    ceaseAnimation();
                    var destDragPosition = -pos/(paneHeight-contentHeight) * maxY;
                    if (!preventAni || settings.animateTo) {
                        _animateToPosition = destDragPosition;
                        _animateToInterval = setInterval(animateToPosition, settings.animateInterval);
                    } else {
                        positionDrag(destDragPosition);
                    }
                };
                $this[0].scrollTo = scrollTo;
                
                $this[0].scrollBy = function(delta)
                {
                    var currentPos = -parseInt($pane.css('top')) || 0;
                    scrollTo(currentPos + delta);
                };
                
                initDrag();
                
                scrollTo(-currentScrollPosition, true);
                
                jQuery.jScrollPane.active.push($this[0]);

            } else {
                $this.css(
                    {
                        'height':paneHeight+'px',
                        'width':paneWidth-this.originalSidePaddingTotal+'px',
                        'padding':this.originalPadding
                    }
                );
                // remove from active list?
            }
            
        }
    )
};

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