public async Task <bool> EnrollUserToLessonAsync(string userId, int lessonId)
{
await CheckIfUserAndLessonExistsAsync(userId, lessonId);
if (this.IsAlreadyEnrolledInLesson(userId, lessonId))
{
throw new InvalidOperationException(ExceptionConstants.AlreadyEnrolledInLessonErrorMessage);
}
int? seatsLeft = this.SeatsLeftInLesson(lessonId);
bool canJoin = seatsLeft.HasValue == false || seatsLeft.Value > 0;
if (canJoin == false)
{
return(false);
}
LessonUser lessonUser = new LessonUser()
{
UserId = userId,
LessonId = lessonId,
EnrollmentDate = DateTime.UtcNow,
};
await this.dbContext.LessonsUsers.AddAsync(lessonUser);
await this.dbContext.SaveChangesAsync();
return(true);
}
public bool IsAlreadyEnrolledInLesson(string userId, int lessonId)
{
LessonUser enrollment = this.GetEnrollment(userId, lessonId);
bool isAlreadyEnrolled = enrollment != null;
return(isAlreadyEnrolled);
}
private LessonUser GetEnrollment(string userId, int lessonId)
{
LessonUser enrollment = this.dbContext.LessonsUsers
.Where(lu => lu.UserId == userId && lu.LessonId == lessonId)
.FirstOrDefault();
return(enrollment);
}
public async Task <bool> RemoveUserFromLessonAsync(string userId, int lessonId)
{
await CheckIfUserAndLessonExistsAsync(userId, lessonId);
if (this.IsAlreadyEnrolledInLesson(userId, lessonId) == false)
{
return(false);
}
LessonUser enrollment = this.GetEnrollment(userId, lessonId);
this.dbContext.LessonsUsers.Remove(enrollment);
await this.dbContext.SaveChangesAsync();
return(true);
}
