var mediaQueryMatches = function(property, r) {
	var style = document.getElementById('binarysearch');
	var dummyElement = document.getElementById('dummyElement');
	style.sheet.insertRule('@media (' + property + ':' + r + ') {#dummyElement ' + '{text-decoration: underline} }', 0);
	var matched = getComputedStyle(dummyElement, null).textDecoration == 'underline';
	style.sheet.deleteRule(0);
	return matched;
};

var mediaQueryBinarySearch = function(property, unit, a, b, maxIter, epsilon) {
	var mid = (a + b)/2;
	if (maxIter == 0 || b - a < epsilon) return mid;
	if (mediaQueryMatches(property, mid + unit)) {
		return mediaQueryBinarySearch(property, unit, mid, b, maxIter-1, epsilon);
	} else {
		return mediaQueryBinarySearch(property, unit, a, mid, maxIter-1, epsilon);
	}
};


var BrowserDetect = {
	init: function () {
		this.browser = this.searchString(this.dataBrowser) || "An unknown browser";
		this.version = this.searchVersion(navigator.userAgent)
			|| this.searchVersion(navigator.appVersion)
			|| "an unknown version";
		this.OS = this.searchString(this.dataOS) || "an unknown OS";
		this.zoom = this.searchZoomRatio();
	},
	searchString: function (data) {
		for (var i=0;i<data.length;i++)	{
			var dataString = data[i].string;
			var dataProp = data[i].prop;
			this.versionSearchString = data[i].versionSearch || data[i].identity;
			if (dataString) {
				if (dataString.indexOf(data[i].subString) != -1)
					return data[i].identity;
			}
			else if (dataProp)
				return data[i].identity;
		}
	},
	searchVersion: function (dataString) {
		var index = dataString.indexOf(this.versionSearchString);
		if (index == -1) return;
		return parseFloat(dataString.substring(index+this.versionSearchString.length+1));
	},
	searchZoomRatio: function () {
		var name = this.browser;
		var ver = this.version;
		var zoom = 1;
		if (name == 'Explorer') {
			if (ver > -1) {
				if (ver == 8) {
					zoom = screen.deviceXDPI / screen.systemXDPI;//screen.systemXDPI / screen.logicalXDPI;
				}
				else if (ver == 7) {
					var r = document.body.getBoundingClientRect();
					zoom = (r.right-r.left)/document.body.offsetWidth;
				}
				else if (ver == 9) {
					zoom = screen.deviceXDPI / screen.systemXDPI;
				}
			}
		}
		else if (name == 'Chrome' || name == 'Safari') {
			var documentWidthCss = Math.max(document.documentElement.clientWidth, document.documentElement.scrollWidth, document.documentElement.offsetWidth);
			zoom = document.width / documentWidthCss;
		}
		else if (name == 'Opera') {
			var fixedDiv = document.createElement('div');
			fixedDiv.style.position = 'fixed';
			fixedDiv.style.border = '5px solid blue';
			fixedDiv.style.width = '100%';
			fixedDiv.style.height = '100%';
			fixedDiv.style.top = fixedDiv.style.left = '0';
			document.body.appendChild(fixedDiv);
			zoom = window.innerWidth / fixedDiv.offsetWidth;
			document.body.removeChild(fixedDiv);
		}
		else if (name == 'Firefox' && ver >= 4) {
			//document.getElementById('ff35ZoomLevel').innerHTML = screen.width / mediaQueryBinarySearch('min-device-width', 'px', 0, 6000, 20, .0001);
			zoom = Math.round(1000*mediaQueryBinarySearch('min--moz-device-pixel-ratio', '', 0, 10, 20, .0001)) / 1000;
		}
		return zoom;
	},
	refreshZoomRatio: function () {
		this.zoom = this.searchZoomRatio();
	},
	dataBrowser: [
		{
			string: navigator.userAgent,
			subString: "Chrome",
			identity: "Chrome"
		},
		{ 	string: navigator.userAgent,
			subString: "OmniWeb",
			versionSearch: "OmniWeb/",
			identity: "OmniWeb"
		},
		{
			string: navigator.vendor,
			subString: "Apple",
			identity: "Safari",
			versionSearch: "Version"
		},
		{
			prop: window.opera,
			identity: "Opera",
			versionSearch: "Version"
		},
		{
			string: navigator.vendor,
			subString: "iCab",
			identity: "iCab"
		},
		{
			string: navigator.vendor,
			subString: "KDE",
			identity: "Konqueror"
		},
		{
			string: navigator.userAgent,
			subString: "Firefox",
			identity: "Firefox"
		},
		{
			string: navigator.vendor,
			subString: "Camino",
			identity: "Camino"
		},
		{		// for newer Netscapes (6+)
			string: navigator.userAgent,
			subString: "Netscape",
			identity: "Netscape"
		},
		{
			string: navigator.userAgent,
			subString: "MSIE",
			identity: "Explorer",
			versionSearch: "MSIE"
		},
		{
			string: navigator.userAgent,
			subString: "Gecko",
			identity: "Mozilla",
			versionSearch: "rv"
		},
		{ 		// for older Netscapes (4-)
			string: navigator.userAgent,
			subString: "Mozilla",
			identity: "Netscape",
			versionSearch: "Mozilla"
		}
	],
	dataOS : [
		{
			string: navigator.platform,
			subString: "Win",
			identity: "Windows"
		},
		{
			string: navigator.platform,
			subString: "Mac",
			identity: "Mac"
		},
		{
			   string: navigator.userAgent,
			   subString: "iPhone",
			   identity: "iPhone/iPod"
	    },
		{
			string: navigator.platform,
			subString: "Linux",
			identity: "Linux"
		}
	]

};