`
// ==UserScript==
// @name Brightness Fixer
// @author Frenzie
// @version 0.4
// @description Applies darker stylesheets based on the presence of bright backgrounds and includes a day/night switch.
// ==/UserScript==

var bodyBackground = /*@Body background@string@*/'peachpuff'/*@*/;
var maxIterations = /*@Max iterations@int@*/50/*@*/;
var night = /*@Enable automatic night style@bool@*/false/*@*/;
var nightTime = [/*@_Night start (hours)@int@*/19/*@*/,
/*@_Night end (hours)@int@*/10/*@*/];
var thresHoldDay = /*@Brightness threshold day@int@*/245/*@*/;
var thresHoldNight = /*@Brightness threshold night@int@*/242/*@*/;
// from http://userstyles.org/styles/14836
var CSSDay = '\

// * {
// color: #000000 !important;
//
// }
a {color: #0000F4;}
li,html {
background-color: #98FB98 !important;
}
body {
background-color: peachpuff !important;
}
tr,td {
background-color: #90D4FF !important;
}
div {
background-color: #c0c0c0 !important;
}
pre,blockquote {
background-color: yellow !important;
}
select, textarea,
input[name=q], input[type=text], input[type=password], input[type=file] {
background-color: #c6e6e6 !important;
color: #222222 !important;
border-color: #aaaaaa !important;
border: 1px dotted #aaaaaa !important;
}
input[type=button], input[type=submit], input[type=reset] {
background-color: #f3f3b3 !important;
color: #222222 !important;
border-color: #aaaaaa !important;
}
';

function getRGBColor(node,prop)
{
	var rgb=getComputedStyle(node, null).getPropertyValue(prop);
	var r,g,b;
	
	if (node == document.documentElement && rgb == 'transparent')
	{
		node.style.backgroundColor = bodyBackground;
		return false;
	}
	
	if (/#([A-Fa-f0-9]{2})([A-Fa-f0-9]{2})([A-Fa-f0-9]{2})/.exec(rgb))
	{
		r=parseInt(RegExp.$1, 16);
		g=parseInt(RegExp.$2, 16);
		b=parseInt(RegExp.$3, 16);
		return [r, g, b];
	}
	
	return false;
}

function addStyle(type)
{
	var style = document.createElement('style');
	style.setAttribute('type', 'text/css');
	style.textContent = (type == 'night') ? CSSNight : CSSDay;
	//document.body.previousSibling.appendChild(style);// previousSibling might be a comment or something
	//document.getElementsByTagName('head')[0].appendChild(style);// valid, but might be superseded
	document.documentElement.appendChild(style);// not valid, but will supersede potential STYLE elements in document.body
}

function determineBrightness (color)
{
	if (color)
		return (color[0]*299 + color[1]*587 + color[2]*114) / 1000;
	else
		return false;
}
	
function adjustBrightness(brightness)
{
	if (night)
	{
		if ( ( hours < nightTime[0] && hours >= nightTime[1] ) && (brightness > thresHoldDay)	)
		{
			addStyle('day');
			return true;
		}
		else if ( ( hours >= nightTime[0] || hours < nightTime[1] ) && (brightness > thresHoldNight) )
		{
			addStyle('night');
			return true;
		}
	}
	else if (brightness > thresHoldDay)
	{
		addStyle('day');
		return true;
	}
	return false;
}

var allElem = document.getElementsByTagName('*');

for (
	var i=0;
	i<allElem.length && i<maxIterations;// attempt not to impact performance too much vs. effectiveness
	i++
)
{
	var color = getRGBColor(allElem[i],'background-color');
	//opera.postError(i+'  rgb:'+color+' brightness:'+determineBrightness(color));
	if (color && adjustBrightness(determineBrightness(color)))
	{
		break;
	}
}

`