using System;
using System.Net;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;

namespace NPSharp.Authentication
{
	public class AuthenticationHelper
	{
		private string _path;
		private ushort _port;
		private string _host;

		/// <summary>
		/// Gets the username.
		/// </summary>
		/// <value>The username.</value>
		public string Username { get; private set; }

		/// <summary>
		/// Gets the user's e-mail address.
		/// </summary>
		/// <value>The user's e-mail address.</value>
		public string UserEMail { get; private set; }

		/// <summary>
		/// Gets the session token.
		/// </summary>
		/// <value>The session token.</value>
		public string SessionToken { get; private set; }

		/// <summary>
		/// Gets the user identifier.
		/// </summary>
		/// <value>The user identifier.</value>
		public uint UserId { get; private set; }

		/// <summary>
		/// Initializes a new instance of the <see cref="NPSharp.Authentication.TokenRetriever"/> class.
		/// </summary>
		/// <param name="host">Hostname of the authentication endpoint.</param>
		/// <param name="port">Port of the authentication endpoint.</param>
		/// <param name="path">Path of the authentication endpoint.</param>
		public AuthenticationHelper (string host, ushort port = 12003, string path = "/authenticate")
		{
			_host = host;
			_port = port;
			_path = path;
		}

		/// <summary>
		/// Authenticate the specified username and password.
		/// </summary>
		/// <param name="username">The username to use for authentication.</param>
		/// <param name="password">The password to use for authentication.</param>
		public void Authenticate (string username, string password)
		{
			var post = string.Format ("{0}&&{1}", username, password);

			var uri = new UriBuilder {
				Scheme = "http",
				Port = _port,
				Host = _host,
				Path = _path
			}.Uri;

            var req = (HttpWebRequest)WebRequest.Create(uri);
            req.Method = "POST";
            req.ContentType = "application/x-www-form-urlencoded";
            req.AllowAutoRedirect = true;
			using (var reqStream = req.GetRequestStream()) {
				var buffer = Encoding.UTF8.GetBytes (post);
				reqStream.Write (buffer, 0, post.Length);
				reqStream.Flush ();
			}

			// Response will be in this syntax:
			// (ok|fail)#text#userid#username#email#sessiontoken
            var rx = new Regex("^(?<status>ok|fail)#(?<text>.+)#(?<userid>[0-9]+)#(?<username>.+)#(?<usermail>.+)#(?<sessiontoken>.+)$");
			var resp = (HttpWebResponse)req.GetResponse ();
			using (var respStream = resp.GetResponseStream()) {
				using (var respReader = new StreamReader(respStream)) {
					while (!respReader.EndOfStream) {
						var line = respReader.ReadLine ();

						// DW response line found?
						if (!rx.IsMatch (line))
							continue;

						// This is a DW response line, analyze
						var rxm = rx.Match (line);

						// Login succeeded?
						if (rxm.Groups ["status"].Value != "ok")
							throw new Exception (rxm.Groups ["text"].Value);

						// Store all data
						Username = rxm.Groups ["username"].Value;
						UserEMail = rxm.Groups ["usermail"].Value;
						SessionToken = rxm.Groups ["sessiontoken"].Value;
						UserId = uint.Parse (rxm.Groups ["userid"].Value);
					}
				}
			}
		}
	}
}