Using the Enterprise Library (June 2005) with Visual Studio 2005

using System;
using System.Collections.Generic;
using System.Text;
using System.Reflection;
using System.Collections.Specialized;
using System.Globalization;
using System.Configuration;
using System.IO;

namespace Microsoft.Practices.EnterpriseLibrary.Configuration
{
	internal class ConfigurationFilePicker
	{
		private ConfigurationFilePicker()
		{
		}

		public static string Lookup(string configurationFile, string machineConfigurationFile)
		{
			// EntLibConfig tool is allowed to load any configuration file.
			// So check whether EntLibConfig is the process executable.
			// Hint: If GetEntryAssembly() returns null, there is no process executable in the default
			// application domain (e.g. for ASP.NET web applications). In this case, we are clearly not
			// running EntLibConfig.
			if (Assembly.GetEntryAssembly() != null)
			{
				if (string.Compare(Assembly.GetEntryAssembly().GetName().Name, "EntLibConfig", true, CultureInfo.InvariantCulture) == 0)
					return configurationFile;
			}

			// Machine.config file must not be loaded as main configuration file.
			if (string.Compare(configurationFile, machineConfigurationFile, true, CultureInfo.InvariantCulture) == 0)
				throw new ConfigurationErrorsException("Loading machine.config as main configuration file is not supported here.");

			// Retrieve entLibConfigFile key from appsettings.
			NameValueCollection appSettings = System.Configuration.ConfigurationManager.AppSettings;
			string entLibConfigFile = appSettings.Get("entLibConfigFile");
			if (entLibConfigFile == null)
				throw new ConfigurationErrorsException("Unable to find entLibConfigFile key in appSettings section.");

			// Retrieve path of application / web configuration file.
			string appConfigFile = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;
			string appConfigPath = Path.GetDirectoryName(appConfigFile);
			if (!appConfigPath.EndsWith(@"\")) appConfigPath += @"\";

			// entLibConfigFile is appended to appConfigPath.
			if (entLibConfigFile.StartsWith(@"\")) entLibConfigFile = entLibConfigFile.TrimStart(@"\".ToCharArray());
			return appConfigPath + entLibConfigFile;
		}
	}
}