/// <summary>
/// Enrolea new student to a given course. Throws NotFound, PreconditionFailed and DbException.
/// </summary>
/// <param name="id">The ID of the course in which the student is enroling.</param>
/// <param name="addStudentModel">A valid StudentViewModel.</param>
/// <returns>The updated list of students in the course.</returns>
public List<StudentDTO> AddStudentToCourse(int id, AddStudentViewModel addStudentModel)
{
var course = _db.Courses.SingleOrDefault(c => c.ID == id);
if (course == null)
throw new NotFoundException($"No course with ID: {id}");
var student = _db.Students.SingleOrDefault(s => s.SSN == addStudentModel.SSN);
if (student == null)
throw new NotFoundException($"No student with SSN: {addStudentModel.SSN}");
if (course.MaxStudents <= GetStudentCount(course.ID))
throw new PreconditionFailedException("Maximum number of students reached!");
var enroled = _db.CourseEnrolments.SingleOrDefault(
e => e.CourseID == course.ID && e.StudentID == student.ID);
if (enroled != null && enroled.Active)
throw new PreconditionFailedException($"{student.Name} is already enroled in {course.TemplateID}");
var waiting = _db.CourseWaitinglists.SingleOrDefault(w => w.CourseID == id && w.StudentID == student.ID);
if (waiting != null)
{
_db.CourseWaitinglists.Remove(waiting);
_db.SaveChanges();
}
if (enroled != null && !enroled.Active)
{
enroled.Active = true;
}
else
{
_db.CourseEnrolments.Add(new CourseEnrolment
{
CourseID = course.ID,
StudentID = student.ID,
Active = true
});
}
try
{
_db.SaveChanges();
}
catch (Exception e)
{
throw new DbException(e);
}
return GetAllStudents(course.ID);
}
/// <summary>
/// Add a student to a courses waiting list. Throws NotFound PreconditionFailed and DbException.
/// </summary>
/// <param name="id">The ID of the cours the waiting list is for.</param>
/// <param name="addStudentModel">The view model for the student being added</param>
/// <returns>A list of students in the courses waiting list.</returns>
public List<StudentDTO> AddStudentToWaitingList(int id, AddStudentViewModel addStudentModel)
{
var course = _db.Courses.SingleOrDefault(c => c.ID == id);
if (course == null)
throw new NotFoundException($"No course with ID: {id}");
var student = _db.Students.SingleOrDefault(s => s.SSN == addStudentModel.SSN);
if (student == null)
throw new NotFoundException($"No student with SSN: {addStudentModel.SSN}");
var enroled =
_db.CourseEnrolments.SingleOrDefault(ce => ce.CourseID == course.ID && ce.StudentID == student.ID && ce.Active);
if (enroled != null)
throw new PreconditionFailedException($"{student.Name} is enroled in the course");
var waiting = _db.CourseWaitinglists.SingleOrDefault(e => e.CourseID == course.ID && e.StudentID == student.ID);
if (waiting != null)
throw new PreconditionFailedException($"{student.Name} is already on the waiting list for {course.TemplateID}");
_db.CourseWaitinglists.Add(new CourseWaitinglist { CourseID = course.ID, StudentID = student.ID });
try
{
_db.SaveChanges();
}
catch (Exception e)
{
throw new DbException(e);
}
return GetWaitinglist(course.ID);
}
