chapter-organizer/Core/Models/PartialTeam.cs

using Core.Entities;

namespace Core.Models;

public class PartialTeam : Team
{
	public IList<Student> OmittedStudents { get; set; } = null!;

    public override Team CloneWithOmittedStudents(IEnumerable<Student> studentsToOmit)
	{
		var remainingStudents = Students.Where(s => !studentsToOmit.Contains(s)).ToList();
		var omittedStudents = OmittedStudents.Union(Students.Where(studentsToOmit.Contains)).Distinct().ToList();
		return new PartialTeam{Identifier = Identifier, Event = Event, Students = remainingStudents, OmittedStudents = omittedStudents };
	}

	/// <summary>
	/// Creates PartialTeam instances from teams with excluded students.
	/// Aggregates exclusions across all time slots for each team.
	/// </summary>
	/// <param name="teams">The teams to process</param>
	/// <param name="excludedStudents">Dictionary of excluded students: key is (teamId, timeSlotIndex, studentId), value is true if excluded</param>
	/// <returns>Array of teams, with PartialTeam instances for teams with exclusions</returns>
	public static Team[] CreatePartialTeamsFromExclusions(
		IEnumerable<Team> teams,
		Dictionary<(int teamId, int timeSlotIndex, int studentId), bool> excludedStudents)
	{
		return teams.Select(team =>
		{
			// Find all students excluded for this team across all time slots
			var excludedStudentIds = excludedStudents.Keys
				.Where(k => k.teamId == team.Id && excludedStudents[k])
				.Select(k => k.studentId)
				.Distinct()
				.ToHashSet();

			if (excludedStudentIds.Count == 0)
				return team;

			var excludedStudentsList = team.Students.Where(s => excludedStudentIds.Contains(s.Id)).ToList();
			if (excludedStudentsList.Count == 0)
				return team;

			// Create PartialTeam with excluded students
			return team.CloneWithOmittedStudents(excludedStudentsList);
		}).ToArray();
	}
}