/*!
 *
 * portamento  v1.1.1 - 2011-09-02
 * http://simianstudios.com/portamento
 *
 * copyright 2011 kris noble except where noted.
 *
 * dual-licensed under the gplv3 and apache 2.0 licenses:
 * http://www.gnu.org/licenses/gpl-3.0.html
 * http://www.apache.org/licenses/license-2.0
 *
 */
/**
 *
 * creates a sliding panel that respects the boundaries of
 * a given wrapper, and also has sensible behaviour if the
 * viewport is too small to display the whole panel.
 *
 * full documentation at http://simianstudios.com/portamento
 *
 * ----
 *
 * uses the viewportoffset plugin by ben alman aka cowboy:
 * http://benalman.com/projects/jquery-misc-plugins/#viewportoffset
 *
 * uses a portion of cft by juriy zaytsev aka kangax:
 * http://kangax.github.com/cft/#is_position_fixed_supported
 *
 * uses code by matthew eernisse:
 * http://www.fleegix.org/articles/2006-05-30-getting-the-scrollbar-width-in-pixels
 *
 * builds on work by remy sharp:
 * http://jqueryfordesigners.com/fixed-floating-elements/
 *
 */
(function($){
	$.fn.portamento = function(options) {
		// we'll use the window and document objects a lot, so
		// saving them as variables now saves a lot of function calls
		var thiswindow = $(window);
		var thisdocument = $(document);
		/**
		 * note by kris - included here so as to avoid namespace clashes.
		 *
		 * jquery viewportoffset - v0.3 - 2/3/2010
		 * http://benalman.com/projects/jquery-misc-plugins/
		 *
		 * copyright (c) 2010 "cowboy" ben alman
		 * dual licensed under the mit and gpl licenses.
		 * http://benalman.com/about/license/
		 */
	  	$.fn.viewportoffset = function() {
			var win = $(window);
			var offset = $(this).offset();
			return {
	    		left: offset.left - win.scrollleft(),
	      		top: offset.top - win.scrolltop()
	    	};
	  	};
		/**
		 *
		 * a test to see if position:fixed is supported.
		 * taken from cft by kangax - http://kangax.github.com/cft/#is_position_fixed_supported
		 * included here so as to avoid namespace clashes.
		 *
		 */
		function positionfixedsupported () {
			var container = document.body;
	  		if (document.createelement && container && container.appendchild && container.removechild) {
	      		var el = document.createelement("div");
		  		if (!el.getboundingclientrect) {
		      		return null;
		  		}
		  		el.innerhtml = "x";
		  		el.style.csstext = "position:fixed;top:100px;";
		  		container.appendchild(el);
		  		var originalheight = container.style.height, originalscrolltop = container.scrolltop;
		 		container.style.height = "3000px";
		      	container.scrolltop = 500;
		      	var elementtop = el.getboundingclientrect().top;
		      	container.style.height = originalheight;
		      	var issupported = elementtop === 100;
		      	container.removechild(el);
		      	container.scrolltop = originalscrolltop;
		      	return issupported;
	  		}
	  		return null;
		}
		/**
		 *
		 * get the scrollbar width by matthew eernisse.
		 * http://www.fleegix.org/articles/2006-05-30-getting-the-scrollbar-width-in-pixels
		 * included here so as to avoid namespace clashes.
		 *
		 */
		function getscrollerwidth() {
		    var scr = null;
		    var inn = null;
		    var wnoscroll = 0;
		    var wscroll = 0;
		    // outer scrolling div
		    scr = document.createelement('div');
		    scr.style.position = 'absolute';
		    scr.style.top = '-1000px';
		    scr.style.left = '-1000px';
		    scr.style.width = '100px';
		    scr.style.height = '50px';
		    // start with no scrollbar
		    scr.style.overflow = 'hidden';
		    // inner content div
		    inn = document.createelement('div');
		    inn.style.width = '100%';
		    inn.style.height = '200px';
		    // put the inner div in the scrolling div
		    scr.appendchild(inn);
		    // append the scrolling div to the doc
		    document.body.appendchild(scr);
		    // width of the inner div sans scrollbar
		    wnoscroll = inn.offsetwidth;
		    // add the scrollbar
		    scr.style.overflow = 'auto';
		    // width of the inner div width scrollbar
		    wscroll = inn.offsetwidth;
		    // remove the scrolling div from the doc
		    document.body.removechild(document.body.lastchild);
		    // pixel width of the scroller
		    return (wnoscroll - wscroll);
		}
		// ---------------------------------------------------------------------------------------------------
		// get the definitive options
		var opts = $.extend({}, $.fn.portamento.defaults, options);
		// setup the vars accordingly
		var panel = this;
		var wrapper = opts.wrapper;
		var gap = opts.gap;
		var disableworkaround = opts.disableworkaround;
		var fullycapablebrowser = positionfixedsupported();
		if(panel.length != 1) {
			// die gracefully if the user has tried to pass multiple elements
			// (multiple element support is on the todo list!) or no elements...
			return this;
		}
		if(!fullycapablebrowser && disableworkaround) {
			// just stop here, as the dev doesn't want to use the workaround
			return this;
		}
		// wrap the floating panel in a div, then set a sensible min-height and width
		panel.wrap('<div id="portamento_container" />');
		var float_container = $('#portamento_container');
		float_container.css({
			'min-height': panel.outerheight(),
			'width': panel.outerwidth()
		});
		// calculate the upper scrolling boundary
		var paneloffset = panel.offset().top;
		var panelmargin = parsefloat(panel.css('margintop').replace(/auto/, 0));
		var realpaneloffset = paneloffset - panelmargin;
		var topscrollboundary = realpaneloffset - gap;
		// a couple of numbers to account for margins and padding on the relevant elements
		var wrapperpaddingfix = parsefloat(wrapper.css('paddingtop').replace(/auto/, 0));
		var containermarginfix = parsefloat(float_container.css('margintop').replace(/auto/, 0));
		// do some work to fix ie misreporting the document width
		var iefix = 0;
		var ismsie = /*@cc_on!@*/0;
		if (ismsie) {
			iefix = getscrollerwidth() + 4;
		}
		// ---------------------------------------------------------------------------------------------------
		thiswindow.bind("scroll.portamento", function () {
			if(thiswindow.height() > panel.outerheight() && thiswindow.width() >= (thisdocument.width() - iefix)) { // don't scroll if the window isn't big enough
				var y = thisdocument.scrolltop(); // current scroll position of the document
				if (y >= (topscrollboundary)) { // if we're at or past the upper scrolling boundary
					if((panel.innerheight() - wrapper.viewportoffset().top) - wrapperpaddingfix + gap >= wrapper.height()) { // if we're at or past the bottom scrolling boundary
						if(panel.hasclass('fixed') || thiswindow.height() >= panel.outerheight()) { // check that there's work to do
							panel.removeclass('fixed');
							panel.css('top', (wrapper.height() - panel.innerheight()) + 'px');
						}
					} else { // if we're somewhere in the middle
						panel.addclass('fixed');
						if(fullycapablebrowser) { // supports position:fixed
							panel.css('top', gap + 'px'); // to keep the gap
						} else {
							panel.clearqueue();
							panel.css('position', 'absolute').animate({top: (0 - float_container.viewportoffset().top + gap)});
						}
					}
				} else {
					// if we're above the top scroll boundary
					panel.removeclass('fixed');
					panel.css('top', '0'); // remove any added gap
				}
			} else {
				panel.removeclass('fixed');
			}
		});
		// ---------------------------------------------------------------------------------------------------
		thiswindow.bind("resize.portamento", function () {
			// stop users getting undesirable behaviour if they resize the window too small
			if(thiswindow.height() <= panel.outerheight() || thiswindow.width() < thisdocument.width()) {
				if(panel.hasclass('fixed')) {
					panel.removeclass('fixed');
					panel.css('top', '0');
				}
			} else {
				thiswindow.trigger('scroll.portamento'); // trigger the scroll event to place the panel correctly
			}
		});
		// ---------------------------------------------------------------------------------------------------
		thiswindow.bind("orientationchange.portamento", function () {
			// if device orientation changes, trigger the resize event
			thiswindow.trigger('resize.portamento');
		});
		// ---------------------------------------------------------------------------------------------------
		// trigger the scroll event immediately so that the panel is positioned correctly if the page loads anywhere other than the top.
		thiswindow.trigger('scroll.portamento');
	    // return this to maintain chainability
	    return this;
	};
	// set some sensible defaults
	$.fn.portamento.defaults = {
	  'wrapper'				: $('body'), // the element that will act as the sliding panel's boundaries
	  'gap'					: 10, // the gap (in pixels) left between the top of the viewport and the top of the panel
	  'disableworkaround' 	: false // option to disable the workaround for not-quite capable browsers
	};
})(jquery);