using System;
using System.Configuration;
using System.Web;
using System.IO;
using System.Reflection;
using System.Net.Mail;
using System.Net.Configuration;

namespace CSharpVitamins
{
	public static class MailHelper
	{
		static bool? _isUsingPickupDirectory;

		/// <summary>
		/// Gets a value to indicate if the default SMTP Delivery 
		/// method is SpecifiedPickupDirectory
		/// </summary>
		public static bool IsUsingPickupDirectory
		{
			get
			{
				if (!_isUsingPickupDirectory.HasValue)
				{
					Configuration config = WebConfigurationManager.OpenWebConfiguration("~/web.config");
					MailSettingsSectionGroup mail = (MailSettingsSectionGroup)config.GetSectionGroup("system.net/mailSettings");
					_isUsingPickupDirectory = mail.Smtp.DeliveryMethod == SmtpDeliveryMethod.SpecifiedPickupDirectory;
				}
				return _isUsingPickupDirectory.Value;
			}
		}

		/// <summary>
		/// Sets the default PickupDirectoryLocation for the SmtpClient.
		/// </summary>
		/// <remarks>
		/// This method should be called to set the PickupDirectoryLocation 
		/// for the SmtpClient at runtime (Application_Start)
		/// 
		/// Reflection is used to set the private variable located in the 
		/// internal class for the SmtpClient's mail configuration: 
		/// System.Net.Mail.SmtpClient.MailConfiguration.Smtp.SpecifiedPickupDirectory.PickupDirectoryLocation
		/// 
		/// The folder must exist.
		/// </remarks>
		/// <param name="path"></param>
		public static void SetPickupDirectoryLocation(string path)
		{
			BindingFlags instanceFlags = BindingFlags.Instance | BindingFlags.NonPublic;
			PropertyInfo prop;
			object mailConfiguration, smtp, specifiedPickupDirectory;

			// get static internal property: MailConfiguration
			prop = typeof(SmtpClient).GetProperty("MailConfiguration", BindingFlags.Static | BindingFlags.NonPublic);
			mailConfiguration = prop.GetValue(null, null);

			// get internal property: Smtp
			prop = mailConfiguration.GetType().GetProperty("Smtp", instanceFlags);
			smtp = prop.GetValue(mailConfiguration, null);

			// get internal property: SpecifiedPickupDirectory
			prop = smtp.GetType().GetProperty("SpecifiedPickupDirectory", instanceFlags);
			specifiedPickupDirectory = prop.GetValue(smtp, null);

			// get private field: pickupDirectoryLocation, then set it to the supplied path
			FieldInfo field = specifiedPickupDirectory.GetType().GetField("pickupDirectoryLocation", instanceFlags);
			field.SetValue(specifiedPickupDirectory, path);
		}

		/// <summary>
		/// Sets the default PickupDirectoryLocation for the SmtpClient 
		/// to the relative path from the current web root.
		/// </summary>
		/// <param name="path">Relative path to the web root</param>
		public static void SetRelativePickupDirectoryLocation(string path)
		{
			SetPickupDirectoryLocation(HttpRuntime.AppDomainAppPath, path);
		}

		/// <summary>
		/// Sets the default PickupDirectoryLocation for the SmtpClient.
		/// </summary>
		/// <remarks>
		/// This is a shortcut for passing in two paths, which are then 
		/// combined to set the pickup directory.
		/// </remarks>
		/// <param name="path1">Base path</param>
		/// <param name="path2">Relative path to be combined with </param>
		public static void SetPickupDirectoryLocation(string path1, string path2)
		{
			SetPickupDirectoryLocation(Path.Combine(path1, path2));
		}
	}
}