jQuery.extend({
	dechex: function(dec) {
		return ((dec < 16) ? "0" : "") + dec.toString(16);
	},
	zebraDecay: function(x) {
		return parseInt(Math.max(x - 16, 0, x * 0.8));
	}
});

jQuery.fn.extend({
	// highlight alternative table rows
	applyZebra: function() {
		if (jQuery(this).hasClass('noZebra')) return;
		
		jQuery('tr:nth-child(odd)', this).each(function(){
			var row = jQuery(this);
				
			if (row.hasClass('odd') || row.hasClass('even')) return true;
			
			var rowBg = row.css('background-color');
			
			// TODO: determine which browsers will say if tds are transparent
			// and allow us skip processing those tds
			row.children('td').each(function(){
				
				var cell = jQuery(this);
					
				if (cell.hasClass('footer') || cell.hasClass('noZebra')) return true;
					
				var r=-1, g=-1, b=-1;
				
				// get colour from cell
				var oc = cell.css('background-color');
				if (typeof oc=="undefined" || oc == "transparent" || oc == 'rgba(0, 0, 0, 0)') {
					// try to get colour from row
					oc = rowBg;
				}
				if (typeof oc=="undefined" || oc == "transparent" || oc == 'rgba(0, 0, 0, 0)') {
					r = g = b = 255;
					
				} else {
					
					if (oc.length == 4 && oc.substr(0,1) == '#') { // handle short values
						oc = "#"+oc.charAt(1)+oc.charAt(1)+oc.charAt(2)+
							oc.charAt(2)+oc.charAt(3)+oc.charAt(3);
					}
					if (oc.length == 7 && oc.substr(0,1) == '#') {
						r=parseInt(oc.substr(1,2),16);
						g=parseInt(oc.substr(3,2),16);
						b=parseInt(oc.substr(5,2),16);
				
					} else if (oc.substr(0,4) == 'rgb(') {
						var rgb = oc.substr(4,oc.length-5).split(",");
						r = rgb[0];
						g = rgb[1];
						b = rgb[2];
					} else {
						/* if it's a named colour, we don't know how to interpret it
						*  so will do nothing to it
						*
						*  Note that Firefox will store named colours as their RGB values
						*  but IE & opera won't
						*/
						//alert(oc);
					}
				}
				
				if (r >= 0 && g >= 0 && b >= 0) {
					// get darker colour from original
					r = jQuery.zebraDecay(r);
					g = jQuery.zebraDecay(g);
					b = jQuery.zebraDecay(b);
					cell.css('background-color', "#"+jQuery.dechex(r)+jQuery.dechex(g)+jQuery.dechex(b));
				}
			});
		});
	}
});

$(function() {
	$('table.data > tbody > tr:nth-child(odd)').addClass('odd');
	$('table.data > tr:nth-child(odd)').addClass('odd');
});

// vim: syntax=javascript st=4 ts=4 sw=4 tw=79