//
// System.Web.Security.FormsAuthentication
//
// Authors:
//	Gonzalo Paniagua Javier (gonzalo@ximian.com)
//
// (C) 2002 Ximian, Inc (http://www.ximian.com)
//

using System;
using System.Collections;
using System.Security.Cryptography;
using System.Text;
using System.Web;
using System.Web.Configuration;
using System.Web.Util;

namespace System.Web.Security
{
	public sealed class FormsAuthentication
	{
		static string authConfigPath = "system.web/authentication";
		static bool initialized;
		static string cookieName;
		static string cookiePath;
		static int timeout;
		static FormsProtectionEnum protection;

		public static bool Authenticate (string name, string password)
		{
			if (name == null || password == null)
				return false;

			Initialize ();
			HttpContext context = HttpContext.Current;
			AuthConfig config = context.GetConfig (authConfigPath) as AuthConfig;
			Hashtable users = config.CredentialUsers;
			string stored = users [name] as string;
			if (stored == null)
				return false;

			switch (config.PasswordFormat) {
			case FormsAuthPasswordFormat.Clear:
				/* Do nothing */
				break;
			case FormsAuthPasswordFormat.MD5:
				stored = HashPasswordForStoringInConfigFile (stored, "MD5");
				break;
			case FormsAuthPasswordFormat.SHA1:
				stored = HashPasswordForStoringInConfigFile (stored, "SHA1");
				break;
			}

			return (password == stored);
		}

		public static FormsAuthenticationTicket Decrypt (string encryptedTicket)
		{
			if (encryptedTicket == null || encryptedTicket == String.Empty)
				throw new ArgumentException ("Invalid encrypted ticket", "encryptedTicket");

			Initialize ();
			byte [] bytes = MachineKeyConfigHandler.GetBytes (encryptedTicket, encryptedTicket.Length);
			//TODO: decrypt
			string decrypted = WebEncoding.Encoding.GetString (bytes);
			FormsAuthenticationTicket ticket = null;
			try {
				string [] values = decrypted.Split ((char) 1, (char) 2, (char) 3, (char) 4, (char) 5, (char) 6, (char) 7);
				if (values.Length != 8)
					throw new Exception (values.Length + " " + encryptedTicket);

				ticket = new FormsAuthenticationTicket (Int32.Parse (values [0]),
									values [1],
									new DateTime (Int64.Parse (values [2])),
									new DateTime (Int64.Parse (values [3])),
									(values [4] == "1"),
									values [5],
									values [6]);
			} catch (Exception e) {
				throw new ArgumentException ("Invalid encrypted ticket", "encryptedTicket", e);
			}

			return ticket;
		}

		public static string Encrypt (FormsAuthenticationTicket ticket)
		{
			if (ticket == null)
				throw new ArgumentNullException ("ticket");

			Initialize ();
			StringBuilder allTicket = new StringBuilder ();
			allTicket.Append (ticket.Version);
			allTicket.Append ('\u0001');
			allTicket.Append (ticket.Name);
			allTicket.Append ('\u0002');
			allTicket.Append (ticket.IssueDate.Ticks);
			allTicket.Append ('\u0003');
			allTicket.Append (ticket.Expiration.Ticks);
			allTicket.Append ('\u0004');
			allTicket.Append (ticket.IsPersistent ? '1' : '0');
			allTicket.Append ('\u0005');
			allTicket.Append (ticket.UserData);
			allTicket.Append ('\u0006');
			allTicket.Append (ticket.CookiePath);
			allTicket.Append ('\u0007');
			//if (protection == FormsProtectionEnum.None)
				return GetHexString (allTicket.ToString ());
			//TODO: encrypt and validate
		}

		[MonoTODO]
		public static HttpCookie GetAuthCookie (string userName, bool createPersistentCookie)
		{
			throw new NotImplementedException ();
		}

		[MonoTODO]
		public static HttpCookie GetAuthCookie (string userName, bool createPersistentCookie, string strCookiePath)
		{
			throw new NotImplementedException ();
		}
		[MonoTODO]
		public static string GetRedirectUrl (string userName, bool createPersistentCookie)
		{
			throw new NotImplementedException ();
		}

		static string GetHexString (string str)
		{
			return GetHexString (WebEncoding.Encoding.GetBytes (str));
		}

		static string GetHexString (byte [] bytes)
		{
			StringBuilder result = new StringBuilder (bytes.Length * 2);
			foreach (byte b in bytes)
				result.AppendFormat ("{0:x2}", (int) b);

			return result.ToString ();
		}

		public static string HashPasswordForStoringInConfigFile (string password, string passwordFormat)
		{
			if (password == null)
				throw new ArgumentNullException ("password");

			if (passwordFormat == null)
				throw new ArgumentNullException ("passwordFormat");

			byte [] bytes;
			if (String.Compare (passwordFormat, "MD5", true) == 0) {
				bytes = MD5.Create ().ComputeHash (WebEncoding.Encoding.GetBytes (password));
			} else if (String.Compare (passwordFormat, "SHA1", true) == 0) {
				bytes = SHA1.Create ().ComputeHash (WebEncoding.Encoding.GetBytes (password));
			} else {
				throw new ArgumentException ("The format must be either MD5 or SHA1", "passwordFormat");
			}

			return GetHexString (bytes);
		}

		public static void Initialize ()
		{
			if (initialized)
				return;

			lock (typeof (FormsAuthentication)) {
				if (initialized)
					return;

				HttpContext context = HttpContext.Current;
				AuthConfig authConfig = context.GetConfig (authConfigPath) as AuthConfig;
				if (authConfig != null) {
					cookieName = authConfig.CookieName;
					timeout = authConfig.Timeout;
					cookiePath = authConfig.CookiePath;
					protection = authConfig.Protection;
				} else {
					cookieName = ".MONOAUTH";
					timeout = 30;
					cookiePath = "/";
					protection = FormsProtectionEnum.All;
				}

				initialized = true;
			}
		}

		[MonoTODO]
		public static void RedirectFromLoginPage (string userName, bool createPersistentCookie)
		{
			throw new NotImplementedException ();
		}

		[MonoTODO]
		public static void RedirectFromLoginPage (string userName, bool createPersistentCookie, string strCookiePath)
		{
			throw new NotImplementedException ();
		}
		[MonoTODO]
		public static FormsAuthenticationTicket RenewTicketIfOld (FormsAuthenticationTicket tOld)
		{
			throw new NotImplementedException ();
		}

		[MonoTODO]
		public static void SetAuthCookie (string userName, bool createPersistentCookie)
		{
			throw new NotImplementedException ();
		}

		[MonoTODO]
		public static void SetAuthCookie (string userName, bool createPersistentCookie, string strCookiePath)
		{
			throw new NotImplementedException ();
		}
		[MonoTODO]
		public static void SignOut ()
		{
			throw new NotImplementedException ();
		}

		[MonoTODO]
		public static string FormsCookieName
		{
			get {
				throw new NotImplementedException ();
			}
		}

		[MonoTODO]
		public static string FormsCookiePath
		{
			get {
				throw new NotImplementedException ();
			}
		}
	}
}