public HttpResponseMessage PostRegisterUser(UserModel model)
        {
            var responseMsg = this.PerformOperationAndHandleExceptions(
                () =>
                {
                    var context = new ForumContext();
                    using (context)
                    {
                        this.ValidateUsername(model.Username);
                        this.ValidateNickname(model.Nickname);
                        this.ValidateAuthCode(model.AuthCode);
                        var usernameToLower = model.Username.ToLower();
                        var nicknameToLower = model.Nickname.ToLower();
                        var user = context.Users.FirstOrDefault(
                            usr => usr.Username == usernameToLower
                            || usr.Nickname.ToLower() == nicknameToLower);

                        if (user != null)
                        {
                            throw new InvalidOperationException("Users exists");
                        }

                        user = new User()
                        {
                            Username = usernameToLower,
                            Nickname = model.Nickname,
                            AuthCode = model.AuthCode
                        };

                        context.Users.Add(user);
                        context.SaveChanges();

                        user.SessionKey = this.GenerateSessionKey(user.Id);
                        context.SaveChanges();

                        var loggedModel = new LoggedUserModel()
                        {
                            Nickname = user.Nickname,
                            SessionKey = user.SessionKey
                        };

                        var response =
                            this.Request.CreateResponse(HttpStatusCode.Created,
                                            loggedModel);
                        return response;
                    }
                });

            return responseMsg;
        }
        public IQueryable<ThreadModel> GetAll(
            [ValueProvider(typeof(HeaderValueProviderFactory<string>))] string sessionKey)
        {
            var responseMsg = this.PerformOperationAndHandleExceptions(() =>
            {
                var context = new ForumContext();

                // TODO : validateSessionkey??
                var user = context.Users.FirstOrDefault(usr => usr.SessionKey == sessionKey);
                if (user == null)
                {
                    throw new InvalidOperationException("Invalid username or password");
                }

                var threadEntities = context.Threads;
                var models =
                    (from threadEntity in threadEntities
                     select new ThreadModel()
                     {
                         Id = threadEntity.Id,
                         Title = threadEntity.Title,
                         DateCreated = threadEntity.DateCreated,
                         Content = threadEntity.Content,
                         CreatedBy = threadEntity.User.Nickname,
                         Posts = (from postEntity in threadEntity.Posts
                                  select new PostModel()
                                  {
                                      Content = postEntity.Content,
                                      PostDate = postEntity.PostDate,
                                      PostedBy = postEntity.User.Nickname
                                  }),
                         Categories = (from categoryEntity in threadEntity.Categories
                                       select categoryEntity.Name)
                     });
                return models.OrderByDescending(thr => thr.DateCreated);
            });

            return responseMsg;
        }
        public HttpResponseMessage PostThread(Thread thread,
            [ValueProvider(typeof(HeaderValueProviderFactory<string>))] string sessionKey)
        {
            var responseMsg = this.PerformOperationAndHandleExceptions(
              () =>
              {
                  var context = new ForumContext();
                  using (context)
                  {
                      var user = context.Users.FirstOrDefault(usr => usr.SessionKey == sessionKey);
                      if (user == null)
                      {
                          throw new InvalidOperationException("Invalid username or password");
                      }

                      context.Threads.Add(thread);
                      context.SaveChanges();

                      HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.Created, thread);
                      response.Headers.Location = new Uri(Url.Link("DefaultApi", new { id = thread.Id }));

                      return response;
                  }

              });
            return responseMsg;
        }
        public HttpResponseMessage PostLoginUser(UserModel model)
        {
            var responseMsg = this.PerformOperationAndHandleExceptions(
              () =>
              {
                  var context = new ForumContext();
                  using (context)
                  {
                      this.ValidateUsername(model.Username);
                      this.ValidateAuthCode(model.AuthCode);
                      var usernameToLower = model.Username.ToLower();
                      var user = context.Users.FirstOrDefault(
                          usr => usr.Username == usernameToLower
                          && usr.AuthCode == model.AuthCode);

                      if (user == null)
                      {
                          throw new InvalidOperationException("Invalid username or password");
                      }
                      if (user.SessionKey == null)
                      {
                          user.SessionKey = this.GenerateSessionKey(user.Id);
                          context.SaveChanges();
                      }

                      var loggedModel = new LoggedUserModel()
                      {
                          Nickname = user.Nickname,
                          SessionKey = user.SessionKey
                      };

                      var response =
                          this.Request.CreateResponse(HttpStatusCode.Created,
                                          loggedModel);
                      return response;
                  }
              });

            return responseMsg;
        }
        public HttpResponseMessage PutLogoutUser(
            [ValueProvider(typeof(HeaderValueProviderFactory<string>))] string sessionKey)
        {
            var responseMsg = this.PerformOperationAndHandleExceptions(
              () =>
              {
                  var context = new ForumContext();
                  using (context)
                  {
                      this.ValidateSessionKey(sessionKey);

                      var user = context.Users.FirstOrDefault(u => u.SessionKey == sessionKey);

                      if (user == null)
                      {
                          throw new InvalidOperationException("Invalid user");
                      }

                      user.SessionKey = null;
                      context.SaveChanges();

                      var response =
                          this.Request.CreateResponse(HttpStatusCode.OK);
                      return response;
                  }
              });

            return responseMsg;
        }
 public HttpResponseMessage PutLogoutUser(string sessionKey)
 {
     var responseMsg = this.PerformOperationAndHandleExceptions(() =>
     {
         var context = new ForumContext();
         using (context)
         {
             var user = context.Users.FirstOrDefault(u => u.SessionKey == sessionKey);
             if (user != null)
             {
                 user.SessionKey = null;
                 context.SaveChanges();
             }
         }
         var response = this.Request.CreateResponse(HttpStatusCode.OK);
         return response;
     });
     return responseMsg;
 }