public async Task <ResponseModel> UnlockContent(int currentContentNo, int levelNo, Guid traineeId)
        {
            int serialNumber = currentContentNo + 1;

            /*
             * is the content is allowed to be unlocked by this user?
             * did the user finished the previous content/quiz? skip if the previous is 0
             * insert new history entry
             */
            Level currentLevel = await Db.Levels.FirstOrDefaultAsync(x => x.No == levelNo);

            Content nextContent = await Db.Contents.FirstOrDefaultAsync(x => x.No == serialNumber && x.LevelId == currentLevel.Id);

            ResponseModel response = await validationService.IsValidRequestAsync(nextContent.Id, traineeId);

            if (response.IsSuccess)
            {
                if (currentContentNo > 0)
                {
                    Content currentContent = await Db.Contents.FirstOrDefaultAsync(x => x.No == currentContentNo && x.LevelId == currentLevel.Id);

                    TraineeQuizHistory prevHistory = await
                                                     Db.TraineeQuizHistories.FirstOrDefaultAsync(
                        x => x.ContentId == currentContent.Id && x.TraineeId == traineeId);

                    if (!prevHistory.IsCompleted)
                    {
                        response = new ResponseModel(null, false, MessageContainer.PreviousContentIsUncompleted);
                    }
                }
                if (response.IsSuccess)
                {
                    var history = new TraineeHistory()
                    {
                        ContentId    = nextContent.Id,
                        TraineeId    = traineeId,
                        LastAccessed = DateTime.Now,
                        Unlocked     = DateTime.Now,
                        Point        = 0,
                    };
                    Db.TraineeHistories.Add(history);
                    await Db.SaveChangesAsync();

                    response =
                        new ResponseModel(new TraineeHistory()
                    {
                        Id        = history.Id,
                        ContentId = history.ContentId,
                        TraineeId = history.TraineeId
                    });
                }
            }

            return(response);
        }
        public async Task <bool> IsUnlocked(Guid contentId, Guid traineeId)
        {
            TraineeHistory history = await Db.TraineeHistories.FirstOrDefaultAsync(x => x.ContentId == contentId && x.TraineeId == traineeId);

            return(history != null);
        }