public void AddStudentToCourse(int courseId, Student student)
{
var course = _courseRepository.GetCourse(courseId);
if (course == default(CourseEntity))
{
throw new CourseNotFound();
}
if (course.Capacity == 0)
{
throw new CourseFull();
}
var existingStudent = _studentRepository.GetStudentByEmail(student.Email);
if (existingStudent != default(StudentEntity))
{
throw new DuplicatedEmail();
}
var studentEntity = _mapper.Map <StudentEntity>(student);
_courseRepository.AddStudent(courseId, studentEntity);
}