feat: добавил ограничение записи на лекции

backend/UniVerse.Infrastructure/Services/LectureService.cs

@@ -6,6 +6,7 @@ using UniVerse.Application.Interfaces;
 using UniVerse.Application.Mappings;
 using UniVerse.Domain.Entities;
 using UniVerse.Domain.Exceptions;
+using UniVerse.Domain.Services;
 using UniVerse.Infrastructure.Data;
 
 namespace UniVerse.Infrastructure.Services;
@@ -124,6 +125,15 @@ public class LectureService : ILectureService
             throw new ConflictException("Lecture is full.");
         if (lecture.Enrollments.Any(e => e.UserId == userId))
             throw new ConflictException("Already enrolled.");
+
+        var level = await _gamification.CalculateLevelAsync(user.Xp);
+        var enrollmentLimit = EnrollmentSlotPolicy.GetLimitForLevel(level);
+        var activeEnrollments = await _db.LectureEnrollments
+            .CountAsync(e => e.UserId == userId && !e.Attended);
+
+        if (activeEnrollments >= enrollmentLimit)
+            throw new ConflictException("Enrollment limit reached for your level.");
+
         _db.LectureEnrollments.Add(new LectureEnrollment { LectureId = lectureId, UserId = userId });
         await _db.SaveChangesAsync();
         await ScheduleLectureRemindersAsync(lecture, user);