presence/data/Repository/SQLAdminRepository.cs

using data.Repository;
using data.DAO;
using Microsoft.EntityFrameworkCore;
using System.Collections.Generic;
using System.Linq;

namespace data.Repository
{
    public class SQLAdminRepository : IAdminRepository
    {
        private readonly DatabaseContext _context;

        public SQLAdminRepository(DatabaseContext context)
        {
            _context = context;
        }

        public void AddStudentsToGroup(int groupId, IEnumerable<int> studentIds)
        {
            var group = _context.Groups.Include(g => g.Students).FirstOrDefault(g => g.Id == groupId);
            if (group == null) return;

            var studentsToAdd = _context.Students
                .Where(u => studentIds.Contains(u.Id))
                .ToList();

            foreach (var student in studentsToAdd)
            {
                if (!group.Students.Any(u => u.Id == student.Id))
                {
                    group.Students.Add(student);
                }
            }

            _context.SaveChanges();
        }

        public void AddSubjectsToGroup(int groupId, IEnumerable<int> subjectIds)
        {
            var group = _context.Groups.Include(g => g.StudentGroupsSubjects).ThenInclude(s => s.Subject).FirstOrDefault(g => g.Id == groupId);
            if (group == null) return;

            var subjectsToAdd = _context.Subjects
                .Where(s => subjectIds.Contains(s.Id))
                .ToList();

            foreach (var subject in subjectsToAdd)
            {
                if (!group.StudentGroupsSubjects.Any(s => s.Subject.Id == subject.Id))
                {
                    group.StudentGroupsSubjects.Add(new StudentGroupSubject { Subject = subject });
                }
            }

            _context.SaveChanges();
        }
    }
}