using System;
using System.Management;
using System.Text.RegularExpressions;

/// <summary>
/// Gets Operating System Name, Service Pack, and Architecture using WMI with the legacy methods as a fallback
/// </summary>
/// <returns>String containing the name of the operating system followed by its service pack (if any) and architecture</returns>
private string getOSInfo()
{
	ManagementObjectSearcher objMOS = new ManagementObjectSearcher("SELECT * FROM  Win32_OperatingSystem");

	//Variables to hold our return value
	string os = "";
	int OSArch = 0;

	try
	{
		foreach (ManagementObject objManagement in objMOS.Get())
		{
			// Get OS version from WMI - This also gives us the edition
			object osCaption = objManagement.GetPropertyValue("Caption");
			if (osCaption != null)
			{
				// Remove all non-alphanumeric characters so that only letters, numbers, and spaces are left.
				string osC = Regex.Replace(osCaption.ToString(),"[^A-Za-z0-9 ]","");
				//string osC = osCaption.ToString();
				// If the OS starts with "Microsoft," remove it.  We know that already
				if (osC.StartsWith("Microsoft"))
				{
					osC = osC.Substring(9);
				}
				// If the OS now starts with "Windows," again... useless.  Remove it.
				if (osC.Trim().StartsWith("Windows"))
				{
					osC = osC.Trim().Substring(7);
				}
				// Remove any remaining beginning or ending spaces.
				os = osC.Trim();
				// Only proceed if we actually have an OS version - service pack is useless without the OS version.
				if(!String.IsNullOrEmpty(os))
				{
					object osSP = null;
					try
					{
						// Get OS service pack from WMI
						osSP = objManagement.GetPropertyValue("ServicePackMajorVersion");
						if (osSP != null && osSP.ToString() != "0")
						{
							os += " Service Pack " + osSP.ToString();
						}
						else
						{
							// Service Pack not found.  Try built-in Environment class.
							os += getOSServicePackLegacy();
						}
					}
					catch (Exception)
					{
						// There was a problem getting the service pack from WMI.  Try built-in Environment class.
						os += getOSServicePackLegacy();
					}
				}
				object osA = null;
				try
				{
					// Get OS architecture from WMI
					osA = objManagement.GetPropertyValue("OSArchitecture");
					if (osA != null)
					{
						string osAString = osA.ToString();
						// If "64" is anywhere in there, it's a 64-bit architectore.
						OSArch = (osAString.Contains("64") ? 64 : 32);
					}
				}
				catch (Exception)
				{
				}
			}
		}
	}
	catch (Exception)
	{
	}
	// If WMI couldn't tell us the OS, use our legacy method.
	// We won't get the exact OS edition, but something is better than nothing.
	if (os == "")
	{
		os = getOSLegacy();
	}
	// If WMI couldn't tell us the architecture, use our legacy method.
	if (OSArch == 0)
	{
		OSArch = getOSArchitectureLegacy();
	}
	return os + " " + OSArch.ToString() + "-bit";
}

/// <summary>
/// Gets Operating System Name using .Net's Environment class.
/// </summary>
/// <returns>String containing the name of the operating system followed by its service pack (if any)</returns>
private string getOSLegacy()
{
	//Get Operating system information.
	OperatingSystem os = Environment.OSVersion;
	//Get version information about the os.
	Version vs = os.Version;

	//Variable to hold our return value
	string operatingSystem = "";

	if (os.Platform == PlatformID.Win32Windows)
	{
		//This is a pre-NT version of Windows
		switch (vs.Minor)
		{
			case 0:
				operatingSystem = "95";
				break;
			case 10:
				if (vs.Revision.ToString() == "2222A")
					operatingSystem = "98SE";
				else
					operatingSystem = "98";
				break;
			case 90:
				operatingSystem = "Me";
				break;
			default:
				break;
		}
	}
	else if(os.Platform == PlatformID.Win32NT)
	{
		switch (vs.Major)
		{
			case 3:
				operatingSystem = "NT 3.51";
				break;
			case 4:
				operatingSystem = "NT 4.0";
				break;
			case 5:
				if (vs.Minor == 0)
				{
					operatingSystem = "2000";
				}
				else
				{
					operatingSystem = "XP";
				}
				break;
			case 6:
				if (vs.Minor == 0)
				{
					operatingSystem = "Vista";
				}
				else
				{
					operatingSystem = "7";
				}
				break;
			default:
				break;
		}
	}
	//Make sure we actually got something in our OS check
	//We don't want to just return " Service Pack 2"
	//That information is useless without the OS version.
	if(operatingSystem != "")
	{
		//Got something.  Let's see if there's a service pack installed.
		operatingSystem += getOSServicePackLegacy();
	}
	//Return the information we've gathered.
	return operatingSystem;
}

/// <summary>
/// Gets the installed Operating System Service Pack using .Net's Environment class.
/// </summary>
/// <returns>String containing the operating system's installed service pack (if any)</returns>
private string getOSServicePackLegacy()
{
	// Get service pack from Environment Class
	string sp = Environment.OSVersion.ServicePack;
	if (sp != null && sp.ToString() != "" && sp.ToString() != " ")
	{
		// If there's a service pack, return it with a space in front (for formatting)
		return " " + sp.ToString();
	}
	// No service pack.  Return an empty string
	return "";
}

/// <summary>
/// Gets Operating System Architecture.  This does not tell you if the program in running in
/// 32- or 64-bit mode or if the CPU is 64-bit capable.  It tells you whether the actual Operating
/// System is 32- or 64-bit.
/// </summary>
/// <returns>Int containing 32 or 64 representing the number of bits in the OS Architecture</returns>
private int getOSArchitectureLegacy()
{
	string pa = Environment.GetEnvironmentVariable("PROCESSOR_ARCHITECTURE");
	return ((String.IsNullOrEmpty(pa) || String.Compare(pa,0,"x86",0,3,true) == 0) ? 32 : 64);
}