/* 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 : 5,
                        wheelSpeed : 18,
                        showArrows : false,
                        arrowSize : 0,
                        animateTo : false,
                        dragMinHeight : 35,
                        dragMaxHeight : 35,
                        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();
                                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'})
                                                )
                                        )
                                );

                                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;
                }
        }
);