/// <summary>
/// Remove the record that says a subject needs to run on a specific time
/// </summary>
public void UnForceTime(Subject subject)
{
if (SubjectsWithForcedTimes.Remove(subject))
{
Order();
}
}
/// <summary>
/// Find what time a subject is forced to
/// </summary>
/// <returns>If the subject is not forced on any time, return null</returns>
public Time?GetForcedTime(Subject subject)
{
if (SubjectsWithForcedTimes.Contains(subject))
{
return(AssignedTimes[subject]);
}
return(null);
}
/// <summary>
/// Assign a time to all selected subjects
/// </summary>
private void Order()
{
Stopwatch timerOrder = new Stopwatch();
timerOrder.Restart();
// Check that all forcedTimes are allowed
foreach (Subject subject in SubjectsWithForcedTimes)
{
if (!subject.AllowedDuringSemester(AssignedTimes[subject], this))
{
SubjectsWithForcedTimes.Remove(subject);
}
}
// Remove current time assignments
foreach (Subject subject in SelectedSubjects)
{
if (!SubjectsWithForcedTimes.Contains(subject))
{
AssignedTimes.Remove(subject);
}
}
// This variable works because IEnumerables get evaluated every time a method is called on it. I usually use a local function instead of a variable.
IEnumerable <Subject> RemainingSubjects = SelectedSubjects.Except(SelectedSubjectsSoFar(Time.All)).OrderBy(subject => subject.GetLevel());
for (Time semester = Time.First; MaxCreditPoints.Keys.Contains(semester) || RemainingSubjects.Any(); semester = semester.Next())
{
// If neccessary, add another year to the planner
if (!MaxCreditPoints.Keys.Contains(semester))
{
AddYear();
}
// Fill the semester with subjects that can be chosen
int selectedCredits = SelectedSubjects.Where(subject => AssignedTimes.TryGetValue(subject, out Time selectedTime) && selectedTime == semester).Sum(subject => subject.CreditPoints());
while (selectedCredits < GetMaxCreditPoints(semester))
{
// Prepare a list of what subjects could be chosen
var possibleSubjects = RemainingSubjects;
// Do not pick subjects with forced times later than the current session
possibleSubjects = possibleSubjects.Where(subject => !(SubjectsWithForcedTimes.Contains(subject) && semester.IsEarlierThan(AssignedTimes[subject])));
// Pick from subjects that are allowed during this semester
possibleSubjects = possibleSubjects.Where(subject => subject.AllowedDuringSemester(semester, this));
// Pick from subjects which would not result in Credit Overflow
possibleSubjects = possibleSubjects.Where(subject => subject.CreditPoints() + selectedCredits <= GetMaxCreditPoints(semester));
// Check if any subjects are forced
IEnumerable <Subject> forcedSubjects = possibleSubjects
.Where(subject => SubjectsWithForcedTimes.Contains(subject) && AssignedTimes[subject].IsEarlierThanOrAtTheSameTime(semester));
// If any subjects are forced, only consider the forced subjects
if (forcedSubjects.Any())
{
possibleSubjects = forcedSubjects.OrderBy(subject => AssignedTimes[subject]);
}
// Otherwise, filter subjects according to whether their requisites are completed
else
{
possibleSubjects = possibleSubjects.Where(subject => RequisitesHaveBeenSelected(subject, semester));
}
// Favor subjects that have many other subjects relying on them
possibleSubjects = possibleSubjects.OrderByDescending(subject => RemainingSubjects.Sum(other => IsAbove(parent: other, child: subject, out int size) ? size : 0))
// Favor subjects that cannot fit in many semesters
.ThenBy(subject => subject.Semesters.Select(semester => semester.session).Distinct().Count())
// Favor lower level subjects
.ThenBy(subject => subject.GetLevel())
// Favor subjects that don't require many electives as prerequisites
.ThenBy(subject => subject.Prerequisites.SizeOfElective() + subject.Corequisites.SizeOfElective())
// Favor subjects that are requisites to their Degree (or any course)
.ThenBy(subject => ContentRelations.Any(relation => relation.source is Course && relation.dest == subject) ? 0 : 1);
// Pick the first item from that list
Subject nextSubject = possibleSubjects.FirstOrDefault();
// If no subject was chosen, go to the next semester
if (nextSubject == null)
{
break;
}
// Add the selected subject to this semester
AssignedTimes[nextSubject] = semester;
// Keep track of how many more times this loop can repeat
selectedCredits += nextSubject.CreditPoints();
}
}
if (SelectedSubjects.Except(SelectedSubjectsSoFar(Time.All)).Any())
{
throw new InvalidOperationException("Not all the subjects were added to the table");
}
timerOrder.Stop();
Debug.WriteLine("Ordering Plan: " + timerOrder.ElapsedMilliseconds + "ms");
// Helper functions to determine whether a subject can be picked
bool RequisitesHaveBeenSelected(Subject subject, Time time, Decision requisite = null)
{
// This function goes through a subject's requisites to make sure every SelectedSubject that is a requisite to this subject has already been added to the schedule
// If no requisite has been specified, then this must have been called by outside this function
if (requisite == null)
{
// Check if this is one of those subjects which don't have any actual requisites (eg no data or "permission by special approval")
// If so, assign it an earliest position based on its level
if (subject.Prerequisites.HasBeenCompleted() && subject.Corequisites.HasBeenCompleted())
{
return(time.AsNumber() / 2 >= subject.GetLevel() - 1);
}
// Call this function again but with the prerequisites and corequisites
return(RequisitesHaveBeenSelected(subject, time.Previous(), subject.Prerequisites) && RequisitesHaveBeenSelected(subject, time, subject.Corequisites));
}
// If the requisit is met by the scheduled selected subjects, return true
if (requisite.HasBeenCompleted(this, time))
{
return(true);
}
// If the requisit is an elective, don't process it. Instead, compare the subject's level to the time
if (requisite.IsElective())
{
return(subject.GetLevel() <= time.Next().year);
}
// Iterate over all of the requisite's option
// The requisite's selectionType doesn't matter, all that matters is whether it HasBeenCompleted.
foreach (Option option in requisite.Options)
{
// If the option is a subject that needs to be picked, hasn't been picked, and must come before the current subject: return false
if (option is Content content && !SelectedSubjectsSoFar(time).Contains(content) && OptionMustComeBeforeSubject(parent: subject, child: content as Subject))
{
return(false);
}
/// <summary>
/// Record that a subject needs to run on a specific time
/// </summary>
public void ForceTime(Subject subject, Time time)
{
AssignedTimes[subject] = time;
SubjectsWithForcedTimes.Add(subject);
Order();
}
