var sUserAgent = navigator.userAgent;
var fAppVersion = parseFloat(navigator.appVersion);

function compareVersions(sVersion1, sVersion2) {

    var arrVersion1 = sVersion1.split(".");
    var arrVersion2 = sVersion2.split(".");
    var i = 0;
	
    if (arrVersion1.length > arrVersion2.length) {
        for (i=0; i < arrVersion1.length - arrVersion2.length; i++) {
            arrVersion2.push("0");
        }
    } else if (arrVersion1.length < arrVersion2.length) {
        for (i=0; i < arrVersion2.length - arrVersion1.length; i++) {
            arrVersion1.push("0");
        }    
    }
    
    for (i=0; i < arrVersion1.length; i++) {
 
        if (arrVersion1[i] < arrVersion2[i]) {
            return -1;
        } else if (arrVersion1[i] > arrVersion2[i]) {
            return 1;
        }    
    }
    
    return 0;

}

var isFF = sUserAgent.indexOf("Firefox") > -1;
var isMinFF1_0 = false;
var isMinFF1_5 = false;
var isMinFF2_0 = false;

if (isFF) {
    var fFFVersion;
    var reFFVersion = new RegExp("Firefox/(\\d+\\.\\d+)");
    reFFVersion.test(sUserAgent);
    fFFVersion = parseFloat(RegExp["$1"]);

    isMinFF1_0 = fFFVersion >= 1.0;
    isMinFF1_5 = fFFVersion >= 1.5;
    isMinFF2_0 = fFFVersion >= 2.0;
}

var isOpera = sUserAgent.indexOf("Opera") > -1;
var isMinOpera4 = false;
var isMinOpera5 = false;
var isMinOpera6 = false;
var isMinOpera7 = false;
var isMinOpera7_5 = false;

if (isOpera) {
    var fOperaVersion;
    if(navigator.appName == "Opera") {
        fOperaVersion = fAppVersion;
    } else {
        var reOperaVersion = new RegExp("Opera (\\d+\\.\\d+)");
        reOperaVersion.test(sUserAgent);
        fOperaVersion = parseFloat(RegExp["$1"]);
    }

    isMinOpera4 = fOperaVersion >= 4;
    isMinOpera5 = fOperaVersion >= 5;
    isMinOpera6 = fOperaVersion >= 6;
    isMinOpera7 = fOperaVersion >= 7;
    isMinOpera7_5 = fOperaVersion >= 7.5;
}

var isKHTML = sUserAgent.indexOf("KHTML") > -1 
              || sUserAgent.indexOf("Konqueror") > -1 
              || sUserAgent.indexOf("AppleWebKit") > -1; 
              
var isMinSafari1 = false;
var isMinSafari1_2 = false;
var isMinSafari1_3 = false;
var isMinSafari2 = false;
var isMinKonq2_2 = false;
var isMinKonq3 = false;
var isMinKonq3_1 = false;
var isMinKonq3_2 = false;
var isSafari = false;
var isKonq = false;

if (isKHTML) {
    isSafari = sUserAgent.indexOf("AppleWebKit") > -1;
    isKonq = sUserAgent.indexOf("Konqueror") > -1;

    if (isSafari) {
        var reAppleWebKit = new RegExp("AppleWebKit\\/(\\d+(?:\\.\\d*)?)");
        reAppleWebKit.test(sUserAgent);
        var fAppleWebKitVersion = parseFloat(RegExp["$1"]);

        isMinSafari1 = fAppleWebKitVersion >= 85;
        isMinSafari1_2 = fAppleWebKitVersion >= 124;
        isMinSafari1_3 = fAppleWebKitVersion >= 312;
        isMinSafari2 = fAppleWebKitVersion >= 412;
    } else if (isKonq) {

        var reKonq = new RegExp("Konqueror\\/(\\d+(?:\\.\\d+(?:\\.\\d)?)?)");
        reKonq.test(sUserAgent);
        isMinKonq2_2 = compareVersions(RegExp["$1"], "2.2") >= 0;
        isMinKonq3 = compareVersions(RegExp["$1"], "3.0") >= 0;
        isMinKonq3_1 = compareVersions(RegExp["$1"], "3.1") >= 0;
        isMinKonq3_2 = compareVersions(RegExp["$1"], "3.2") >= 0;
    } 
    
}

var isIE = sUserAgent.indexOf("compatible") > -1 
           && sUserAgent.indexOf("MSIE") > -1
           && !isOpera
           && (sUserAgent.indexOf("Netscape") == -1); 
           
var isMinIE4 = false;
var isMinIE5 = false;
var isMinIE5_5 = false;
var isMinIE6 = false;
var isMinIE7 = false;

if (isIE) {
    var reIE = new RegExp("MSIE (\\d+\\.\\d+);");
    reIE.test(sUserAgent);
    var fIEVersion = parseFloat(RegExp["$1"]);

    isMinIE4 = fIEVersion >= 4;
    isMinIE5 = fIEVersion >= 5;
    isMinIE5_5 = fIEVersion >= 5.5;
    isMinIE6 = fIEVersion >= 6.0;
	isMinIE7 = fIEVersion >= 7.0;
}

var isMoz = sUserAgent.indexOf("Gecko") > -1
            && !isKHTML;
            
var isMinMoz1 = false;
var isMinMoz1_4 = false;
var isMinMoz1_5 = false;

if (isMoz) {
    var reMoz = new RegExp("rv:(\\d+\\.\\d+(?:\\.\\d+)?)");
    reMoz.test(sUserAgent);
    isMinMoz1 = compareVersions(RegExp["$1"], "1.0") >= 0;
    isMinMoz1_4 = compareVersions(RegExp["$1"], "1.4") >= 0;
    isMinMoz1_5 = compareVersions(RegExp["$1"], "1.5") >= 0;
}

var isNS4 = !isIE && !isOpera && !isMoz && !isKHTML 
            && (sUserAgent.indexOf("Mozilla") == 0) 
            && (navigator.appName == "Netscape") 
            && (fAppVersion >= 4.0 && fAppVersion < 5.0);

var isMinNS4 = false;
var isMinNS4_5 = false;
var isMinNS4_7 = false;
var isMinNS4_8 = false;

if (isNS4) {
    isMinNS4 = true;
    isMinNS4_5 = fAppVersion >= 4.5;
    isMinNS4_7 = fAppVersion >= 4.7;
    isMinNS4_8 = fAppVersion >= 4.8;
}

var isWin = (navigator.platform == "Win32") || (navigator.platform == "Windows");
var isMac = (navigator.platform == "Mac68K") || (navigator.platform == "MacPPC") 
            || (navigator.platform == "Macintosh")
            || (navigator.platform == "MacIntel");

var isUnix = (navigator.platform == "X11") && !isWin && !isMac;

var isWinNT4 = false;
var isWin95 = false;
var isWin98 = false;
var isWinME = false;
var isWin2K = false;
var isWinXP = false;
var isWinVista = false;
var isMac68K = false;
var isMacPPC = false;
var isMacIntel = false;
var isSunOS = false;
var isMinSunOS4 = false;
var isMinSunOS5 = false;
var isMinSunOS5_5 = false;

var isMinWin98 = false;
var isMinWinME = false;
var isMinWin2K = false;
var isMinWinXP = false;
var isMinWinVista = false;

if (isWin) {
    isWin95 = sUserAgent.indexOf("Win95") > -1 
              || sUserAgent.indexOf("Windows 95") > -1;
    isWin98 = sUserAgent.indexOf("Win98") > -1 
              || sUserAgent.indexOf("Windows 98") > -1;
    isWinME = sUserAgent.indexOf("Win 9x 4.90") > -1 
              || sUserAgent.indexOf("Windows ME") > -1;
    isWin2K = sUserAgent.indexOf("Windows NT 5.0") > -1 
              || sUserAgent.indexOf("Windows 2000") > -1;
    isWinXP = sUserAgent.indexOf("Windows NT 5.1") > -1 
              || sUserAgent.indexOf("Windows XP") > -1;
    isWinVista = sUserAgent.indexOf("Windows NT 6.0") > -1 
              || sUserAgent.indexOf("Windows Vista") > -1;	//this is a guess since I've not seen this documented
    isWinNT4 = sUserAgent.indexOf("WinNT") > -1 
              || sUserAgent.indexOf("Windows NT") > -1 
              || sUserAgent.indexOf("WinNT4.0") > -1 
              || sUserAgent.indexOf("Windows NT 4.0") > -1 
              && (!isWinME && !isWin2K && !isWinXP && !isWinVista);


	if(isWinVista) {
		isMinWin98 = true;
		isMinWinME = true;
		isMinWin2K = true;
		isMinWinXP = true;
		isMinWinVista = true;
	}
	else if(isWinXP) {
		isMinWin98 = true;
		isMinWinME = true;
		isMinWin2K = true;
		isMinWinXP = true;
	}
	else if(isWin2K) {
		isMinWin98 = true;
		isMinWinME = true;
		isMinWin2K = true;
	}
	else if(isWinME) {
		isMinWin98 = true;
		isMinWinME = true;
	}
	else if(isWin98) {
		isMinWin98 = true;
	}
	
} 

if (isMac) {
    isMac68K = sUserAgent.indexOf("Mac_68000") > -1 
               || sUserAgent.indexOf("68K") > -1;
    isMacPPC = sUserAgent.indexOf("Mac_PowerPC") > -1 
               || sUserAgent.indexOf("PPC") > -1;  
    isMacIntel = sUserAgent.indexOf("Mac_Intel") > -1 
               || sUserAgent.indexOf("Intel") > -1;  
}

if (isUnix) {
    isSunOS = sUserAgent.indexOf("SunOS") > -1;

    if (isSunOS) {
        var reSunOS = new RegExp("SunOS (\\d+\\.\\d+(?:\\.\\d+)?)");
        reSunOS.test(sUserAgent);
        isMinSunOS4 = compareVersions(RegExp["$1"], "4.0") >= 0;
        isMinSunOS5 = compareVersions(RegExp["$1"], "5.0") >= 0;
        isMinSunOS5_5 = compareVersions(RegExp["$1"], "5.5") >= 0;
    }
}