预演

src/Jiaowu.Api/Controllers/AcademicPlanningController.cs

@@ -0,0 +1,621 @@
+using System.ComponentModel.DataAnnotations;
+using Jiaowu.Api.Domain.Academic;
+using Jiaowu.Api.Domain.Identity;
+using Jiaowu.Api.Infrastructure.Auth;
+using Jiaowu.Api.Infrastructure.Graduation;
+using Jiaowu.Api.Infrastructure.Persistence;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+
+namespace Jiaowu.Api.Controllers;
+
+[ApiController]
+[Authorize(Roles = SystemRoles.Student)]
+[Route("api/student/academic-planning")]
+public sealed class AcademicPlanningController(
+    AppDbContext db,
+    ICurrentUserDataScope currentUserDataScope) : ControllerBase
+{
+    [HttpGet]
+    public async Task<ActionResult> Get(CancellationToken cancellationToken)
+    {
+        var loaded = await LoadAsync(cancellationToken);
+        if (loaded.Error is not null) return loaded.Error;
+        var context = loaded.Context!;
+
+        var completion = CurriculumCompletionRules.Evaluate(
+            context.Plan.Modules,
+            context.PassedCourseIds);
+        var planCompletedCredits = context.Courses
+            .Where(x => context.PassedCourseIds.Contains(x.CourseId))
+            .Sum(x => x.Credits);
+        var suggestionIds = AcademicPlanningRules.SuggestNextSemester(
+            context.CourseSnapshots,
+            context.PassedCourseIds,
+            context.InProgressCourseIds,
+            context.NextSemester);
+        var suggestionIdSet = suggestionIds.ToHashSet();
+        var latestAudit = await db.GraduationAuditResults.AsNoTracking()
+            .Where(x =>
+                x.StudentId == context.Student.Id &&
+                x.GraduationAuditBatch!.Status ==
+                    GraduationAuditBatchStatus.Published)
+            .OrderByDescending(x => x.GraduationAuditBatch!.GraduationYear)
+            .ThenByDescending(x => x.GraduationAuditBatch!.PublishedAt)
+            .Select(x => new
+            {
+                BatchName = x.GraduationAuditBatch!.Name,
+                x.GraduationAuditBatch.GraduationYear,
+                x.RequiredCredits,
+                x.EarnedCredits,
+                x.RequiredCourseCount,
+                x.PassedRequiredCourseCount,
+                x.FailedCourseCount,
+                x.MissingCourseNames,
+                x.Conclusion,
+                x.IsOverridden,
+                x.ReviewComment,
+                x.GraduationAuditBatch.PublishedAt
+            })
+            .FirstOrDefaultAsync(cancellationToken);
+
+        var endSemester = Math.Max(
+            context.Plan.Major!.SchoolingYears * 2,
+            context.NextSemester + 3);
+        return Ok(new
+        {
+            Student = new
+            {
+                context.Student.Id,
+                context.Student.StudentNumber,
+                context.Student.Name,
+                context.Student.EnrollmentYear,
+                context.Student.Status,
+                ClassName = context.Student.AdministrativeClass!.Name,
+                MajorName = context.Student.AdministrativeClass.Major!.Name,
+                CollegeName =
+                    context.Student.AdministrativeClass.Major.College!.Name
+            },
+            Plan = new
+            {
+                context.Plan.Id,
+                context.Plan.Name,
+                context.Plan.Version,
+                context.Plan.TotalCredits,
+                SchoolingYears = context.Plan.Major.SchoolingYears,
+                CurrentSemester = context.CurrentSemester,
+                NextSemester = context.NextSemester,
+                StandardGraduationSemester =
+                    context.Plan.Major.SchoolingYears * 2
+            },
+            Baseline = new
+            {
+                EarnedCredits = context.EarnedCredits,
+                PlanCompletedCredits = planCompletedCredits,
+                CreditGap = Math.Max(
+                    context.Plan.TotalCredits - context.EarnedCredits,
+                    0),
+                CompletionRate = context.Plan.TotalCredits <= 0
+                    ? 0
+                    : Math.Min(100, Math.Round(
+                        planCompletedCredits / context.Plan.TotalCredits * 100,
+                        1)),
+                completion.RequirementCount,
+                completion.PassedRequirementCount,
+                completion.MissingRequirements,
+                InProgressCredits = context.Courses
+                    .Where(x => context.InProgressCourseIds.Contains(x.CourseId))
+                    .Sum(x => x.Credits)
+            },
+            Terms = Enumerable.Range(
+                    context.NextSemester,
+                    endSemester - context.NextSemester + 1)
+                .Select(semester => new
+                {
+                    Semester = semester,
+                    Label = FormatSemester(
+                        context.Student.EnrollmentYear,
+                        semester),
+                    IsBeyondStandard =
+                        semester > context.Plan.Major.SchoolingYears * 2
+                }),
+            Courses = context.Courses
+                .OrderBy(x => x.RecommendedSemester)
+                .ThenBy(x => x.CourseCode)
+                .Select(course => new
+                {
+                    course.CourseId,
+                    course.CourseCode,
+                    course.CourseName,
+                    course.Credits,
+                    course.RecommendedSemester,
+                    course.Type,
+                    course.ModuleCode,
+                    course.ModuleName,
+                    Status = context.StatusByCourse[course.CourseId],
+                    IsSuggested = suggestionIdSet.Contains(course.CourseId),
+                    Prerequisites = course.Prerequisites.Select(item => new
+                    {
+                        item.CourseId,
+                        item.CourseCode,
+                        item.CourseName,
+                        IsCompleted =
+                            context.PassedCourseIds.Contains(item.CourseId),
+                        IsInProgress =
+                            context.InProgressCourseIds.Contains(item.CourseId)
+                    })
+                }),
+            NextSemesterSuggestion = suggestionIds.Select(courseId =>
+            {
+                var course = context.CourseById[courseId];
+                return new
+                {
+                    course.CourseId,
+                    course.CourseCode,
+                    course.CourseName,
+                    course.Credits,
+                    course.Type,
+                    Reason = course.Type == CurriculumCourseType.Required &&
+                             course.RecommendedSemester <= context.NextSemester
+                        ? "计划学期已到，且先修条件已满足"
+                        : course.Type == CurriculumCourseType.Required
+                            ? "必修课程，按培养方案顺序推进"
+                            : "用于补足培养模块与总学分"
+                };
+            }),
+            LatestGraduationAudit = latestAudit,
+            Assumptions = new[]
+            {
+                "模拟课程按顺利通过计算，不会写入成绩或正式选课。",
+                $"预计毕业学期按每学期最多 {AcademicPlanningRules.RecommendedSemesterCreditLimit:0} 学分估算。",
+                "当前在读课程按本学期顺利完成计入预测。"
+            }
+        });
+    }
+
+    [HttpPost("simulate")]
+    public async Task<ActionResult> Simulate(
+        AcademicPlanningRequest request,
+        CancellationToken cancellationToken)
+    {
+        var loaded = await LoadAsync(cancellationToken);
+        if (loaded.Error is not null) return loaded.Error;
+        var context = loaded.Context!;
+
+        var selections = request.Terms
+            .SelectMany(term => term.CourseIds.Select(courseId => new
+            {
+                term.Semester,
+                CourseId = courseId
+            }))
+            .ToList();
+        var duplicate = selections
+            .GroupBy(x => x.CourseId)
+            .FirstOrDefault(group => group.Count() > 1);
+        if (duplicate is not null)
+            return ValidationProblem("同一门课程不能安排在多个学期。");
+        if (request.Terms.Any(x =>
+                x.Semester < context.NextSemester ||
+                x.Semester > context.NextSemester + 12))
+            return ValidationProblem("模拟学期超出了可规划范围。");
+
+        var invalidCourse = selections.FirstOrDefault(x =>
+            !context.CourseById.ContainsKey(x.CourseId));
+        if (invalidCourse is not null)
+            return ValidationProblem("模拟计划包含不属于当前培养方案的课程。");
+        var alreadyHandled = selections.FirstOrDefault(x =>
+            context.PassedCourseIds.Contains(x.CourseId) ||
+            context.InProgressCourseIds.Contains(x.CourseId));
+        if (alreadyHandled is not null)
+            return ValidationProblem("已完成或当前在读课程无需重复安排。");
+
+        var plannedSemesters = selections.ToDictionary(
+            x => x.CourseId,
+            x => x.Semester);
+        var projectedCourseIds = context.PassedCourseIds
+            .Concat(context.InProgressCourseIds)
+            .Concat(plannedSemesters.Keys)
+            .ToHashSet();
+        var completion = CurriculumCompletionRules.Evaluate(
+            context.Plan.Modules,
+            projectedCourseIds);
+        var addedCredits = context.Courses
+            .Where(x =>
+                !context.PassedCourseIds.Contains(x.CourseId) &&
+                (context.InProgressCourseIds.Contains(x.CourseId) ||
+                 plannedSemesters.ContainsKey(x.CourseId)))
+            .Sum(x => x.Credits);
+        var projectedEarnedCredits = context.EarnedCredits + addedCredits;
+        var creditGap = Math.Max(
+            context.Plan.TotalCredits - projectedEarnedCredits,
+            0);
+        var prerequisiteIssues = AcademicPlanningRules.FindPrerequisiteIssues(
+            context.CourseSnapshots,
+            context.PassedCourseIds,
+            context.InProgressCourseIds,
+            plannedSemesters);
+        var conflicts = prerequisiteIssues.Select(issue =>
+        {
+            var course = context.CourseById[issue.CourseId];
+            var prerequisite = context.AllCourseLabels.GetValueOrDefault(
+                issue.PrerequisiteCourseId,
+                new CourseLabel(
+                    issue.PrerequisiteCourseId,
+                    "未知课程",
+                    "未找到的先修课程"));
+            return new
+            {
+                Type = "Prerequisite",
+                issue.CourseId,
+                course.CourseName,
+                PrerequisiteCourseId = prerequisite.CourseId,
+                PrerequisiteCourseName = prerequisite.CourseName,
+                issue.PlannedSemester,
+                issue.PrerequisitePlannedSemester,
+                Message = issue.PrerequisitePlannedSemester.HasValue
+                    ? $"《{prerequisite.CourseName}》必须安排在《{course.CourseName}》之前。"
+                    : $"《{course.CourseName}》的先修课程《{prerequisite.CourseName}》尚未完成或安排。"
+            };
+        }).ToList();
+        var workloadWarnings = request.Terms
+            .Select(term => new
+            {
+                term.Semester,
+                Credits = term.CourseIds.Sum(courseId =>
+                    context.CourseById.GetValueOrDefault(courseId)?.Credits ?? 0)
+            })
+            .Where(x =>
+                x.Credits > AcademicPlanningRules.HeavySemesterCreditLimit)
+            .Select(x => new
+            {
+                Type = "Workload",
+                x.Semester,
+                x.Credits,
+                Message =
+                    $"第 {x.Semester} 学期安排了 {x.Credits:0.#} 学分，超过建议上限 {AcademicPlanningRules.HeavySemesterCreditLimit:0.#} 学分。"
+            })
+            .ToList();
+        var timingWarnings = selections
+            .Select(item => new
+            {
+                item.Semester,
+                Course = context.CourseById[item.CourseId]
+            })
+            .Where(x => x.Semester < x.Course.RecommendedSemester)
+            .Select(x => new
+            {
+                Type = "EarlyCourse",
+                x.Course.CourseId,
+                x.Course.CourseName,
+                x.Semester,
+                x.Course.RecommendedSemester,
+                Message =
+                    $"《{x.Course.CourseName}》早于培养方案建议学期修读，请确认课程开设条件。"
+            })
+            .ToList();
+
+        var unresolvedFailedCourseCount = context.FailedCourseIds.Count(
+            courseId => !projectedCourseIds.Contains(courseId));
+        var conclusion = GraduationAuditRules.Evaluate(
+            true,
+            context.Student.Status,
+            context.Plan.TotalCredits,
+            projectedEarnedCredits,
+            completion.RequirementCount,
+            completion.PassedRequirementCount,
+            unresolvedFailedCourseCount);
+        var latestPlannedSemester = plannedSemesters.Count == 0
+            ? context.NextSemester - 1
+            : plannedSemesters.Values.Max();
+        var estimatedSemester =
+            AcademicPlanningRules.EstimateCompletionSemester(
+                context.NextSemester,
+                latestPlannedSemester,
+                creditGap,
+                completion.RequirementCount -
+                completion.PassedRequirementCount);
+        var remainingRequiredSemesterFloor = context.Courses
+            .Where(course =>
+                course.Type == CurriculumCourseType.Required &&
+                !projectedCourseIds.Contains(course.CourseId))
+            .Select(course => course.RecommendedSemester)
+            .DefaultIfEmpty(estimatedSemester)
+            .Max();
+        estimatedSemester = Math.Max(
+            estimatedSemester,
+            remainingRequiredSemesterFloor);
+        var planCompletedCredits = context.Courses
+            .Where(x => projectedCourseIds.Contains(x.CourseId))
+            .Sum(x => x.Credits);
+
+        return Ok(new
+        {
+            Projected = new
+            {
+                EarnedCredits = projectedEarnedCredits,
+                PlanCompletedCredits = planCompletedCredits,
+                CreditGap = creditGap,
+                CompletionRate = context.Plan.TotalCredits <= 0
+                    ? 0
+                    : Math.Min(100, Math.Round(
+                        planCompletedCredits / context.Plan.TotalCredits * 100,
+                        1)),
+                completion.RequirementCount,
+                completion.PassedRequirementCount,
+                completion.MissingRequirements,
+                UnresolvedFailedCourseCount = unresolvedFailedCourseCount,
+                GraduationConclusion = conclusion,
+                EstimatedGraduationSemester = estimatedSemester,
+                EstimatedGraduationTerm = FormatSemester(
+                    context.Student.EnrollmentYear,
+                    estimatedSemester),
+                IsBeyondStandard =
+                    estimatedSemester >
+                    context.Plan.Major!.SchoolingYears * 2
+            },
+            Conflicts = conflicts,
+            Warnings = workloadWarnings.Cast<object>()
+                .Concat(timingWarnings)
+                .ToList(),
+            TermSummaries = request.Terms
+                .OrderBy(x => x.Semester)
+                .Select(term => new
+                {
+                    term.Semester,
+                    Label = FormatSemester(
+                        context.Student.EnrollmentYear,
+                        term.Semester),
+                    CourseCount = term.CourseIds.Count,
+                    Credits = term.CourseIds.Sum(courseId =>
+                        context.CourseById.GetValueOrDefault(courseId)?.Credits ??
+                        0)
+                })
+        });
+    }
+
+    private async Task<LoadResult> LoadAsync(CancellationToken cancellationToken)
+    {
+        var userId = currentUserDataScope.Current.UserId;
+        var student = await db.Students.AsNoTracking()
+            .Include(x => x.AdministrativeClass)
+            .ThenInclude(x => x!.Major)
+            .ThenInclude(x => x!.College)
+            .FirstOrDefaultAsync(x => x.UserId == userId, cancellationToken);
+        if (student is null)
+            return new LoadResult(
+                null,
+                ConflictProblem("当前账号尚未关联学生档案。"));
+
+        var plan = await db.CurriculumPlans.AsNoTracking()
+            .AsSplitQuery()
+            .Include(x => x.Major)
+            .Include(x => x.Modules)
+            .ThenInclude(x => x.Courses)
+            .ThenInclude(x => x.Course)
+            .ThenInclude(x => x!.Prerequisites)
+            .ThenInclude(x => x.PrerequisiteCourse)
+            .Where(x =>
+                x.MajorId == student.AdministrativeClass!.MajorId &&
+                x.EffectiveGrade == student.EnrollmentYear &&
+                x.Status == CurriculumPlanStatus.Published)
+            .OrderByDescending(x => x.PublishedAt)
+            .FirstOrDefaultAsync(cancellationToken);
+        if (plan is null)
+            return new LoadResult(
+                null,
+                ConflictProblem(
+                    $"{student.EnrollmentYear} 级{student.AdministrativeClass!.Major!.Name}尚未发布培养方案。"));
+
+        var courses = plan.Modules
+            .SelectMany(module => module.Courses.Select(item =>
+                new PlanningCourse(
+                    item.CourseId,
+                    item.Course!.Code,
+                    item.Course.Name,
+                    item.Course.Credits,
+                    item.RecommendedSemester,
+                    item.Type,
+                    module.Code,
+                    module.Name,
+                    item.Course.Prerequisites
+                        .Select(prerequisite => new CourseLabel(
+                            prerequisite.PrerequisiteCourseId,
+                            prerequisite.PrerequisiteCourse!.Code,
+                            prerequisite.PrerequisiteCourse.Name))
+                        .OrderBy(x => x.CourseCode)
+                        .ToList())))
+            .GroupBy(x => x.CourseId)
+            .Select(group => group.First())
+            .ToList();
+        var planCourseIds = courses.Select(x => x.CourseId).ToArray();
+
+        var gradeAttempts = await db.GradeRecords.AsNoTracking()
+            .Where(x =>
+                x.StudentId == student.Id &&
+                x.GradeSheet!.Status == GradeSheetStatus.Published)
+            .Select(x => new GradeAttempt(
+                x.GradeSheet!.TeachingTask!.CourseId,
+                x.GradeSheet.TeachingTask.Course!.Credits,
+                x.TotalScore,
+                x.ExamStatus))
+            .ToListAsync(cancellationToken);
+        var passedCourseIds = gradeAttempts
+            .Where(x => StudentCourseProgressRules.IsPassed(
+                new StudentCourseAttemptSnapshot(x.TotalScore, x.ExamStatus)))
+            .Select(x => x.CourseId)
+            .Distinct()
+            .ToHashSet();
+        var failedCourseIds = gradeAttempts
+            .GroupBy(x => x.CourseId)
+            .Where(group => !group.Any(x =>
+                StudentCourseProgressRules.IsPassed(
+                    new StudentCourseAttemptSnapshot(
+                        x.TotalScore,
+                        x.ExamStatus))))
+            .Select(group => group.Key)
+            .ToHashSet();
+        var earnedCredits = gradeAttempts
+            .Where(x => passedCourseIds.Contains(x.CourseId))
+            .GroupBy(x => x.CourseId)
+            .Sum(group => group.Max(x => x.Credits));
+
+        var inProgressCourseIds = await db.TeachingTasks.AsNoTracking()
+            .Where(task =>
+                task.Status == TeachingTaskStatus.Published &&
+                task.AcademicTerm!.IsCurrent &&
+                (task.Classes.Any(item =>
+                     item.AdministrativeClassId ==
+                     student.AdministrativeClassId) ||
+                 db.CourseEnrollments.Any(enrollment =>
+                     enrollment.StudentId == student.Id &&
+                     enrollment.Status == CourseEnrollmentStatus.Enrolled &&
+                     enrollment.CourseSelectionOffering!.TeachingTaskId ==
+                     task.Id)))
+            .Select(x => x.CourseId)
+            .Distinct()
+            .ToListAsync(cancellationToken);
+        var inProgressSet = inProgressCourseIds
+            .Where(planCourseIds.Contains)
+            .Where(courseId => !passedCourseIds.Contains(courseId))
+            .ToHashSet();
+
+        var attemptsByCourse = gradeAttempts
+            .Where(x => planCourseIds.Contains(x.CourseId))
+            .GroupBy(x => x.CourseId)
+            .ToDictionary(x => x.Key, x => x.ToList());
+        var statuses = courses.ToDictionary(
+            x => x.CourseId,
+            x => StudentCourseProgressRules.Evaluate(
+                attemptsByCourse.GetValueOrDefault(x.CourseId, [])
+                    .Select(attempt => new StudentCourseAttemptSnapshot(
+                        attempt.TotalScore,
+                        attempt.ExamStatus)),
+                inProgressSet.Contains(x.CourseId)).Status);
+        var currentTerm = await db.AcademicTerms.AsNoTracking()
+            .Where(x => x.IsCurrent)
+            .OrderByDescending(x => x.StartDate)
+            .FirstOrDefaultAsync(cancellationToken);
+        var currentSemester = CalculateCurrentSemester(
+            student.EnrollmentYear,
+            currentTerm);
+        var snapshots = courses.Select(x =>
+            new AcademicPlanningCourseSnapshot(
+                x.CourseId,
+                x.CourseName,
+                x.Credits,
+                x.RecommendedSemester,
+                x.Type,
+                x.Prerequisites.Select(p => p.CourseId).ToArray()))
+            .ToList();
+        var allLabels = courses
+            .Select(x => new CourseLabel(
+                x.CourseId,
+                x.CourseCode,
+                x.CourseName))
+            .Concat(courses.SelectMany(x => x.Prerequisites))
+            .GroupBy(x => x.CourseId)
+            .ToDictionary(x => x.Key, x => x.First());
+
+        return new LoadResult(
+            new PlanningContext(
+                student,
+                plan,
+                courses,
+                courses.ToDictionary(x => x.CourseId),
+                snapshots,
+                allLabels,
+                passedCourseIds,
+                inProgressSet,
+                failedCourseIds,
+                statuses,
+                earnedCredits,
+                currentSemester,
+                currentSemester + 1),
+            null);
+    }
+
+    private static int CalculateCurrentSemester(
+        int enrollmentYear,
+        AcademicTerm? currentTerm)
+    {
+        if (currentTerm is not null)
+        {
+            return Math.Max(
+                1,
+                currentTerm.Season == TermSeason.Autumn
+                    ? (currentTerm.StartDate.Year - enrollmentYear) * 2 + 1
+                    : (currentTerm.StartDate.Year - enrollmentYear - 1) * 2 + 2);
+        }
+
+        var today = DateOnly.FromDateTime(DateTime.Today);
+        return Math.Max(
+            1,
+            today.Month >= 8
+                ? (today.Year - enrollmentYear) * 2 + 1
+                : (today.Year - enrollmentYear - 1) * 2 + 2);
+    }
+
+    private static string FormatSemester(int enrollmentYear, int semester)
+    {
+        var startYear = enrollmentYear + (semester - 1) / 2;
+        var season = semester % 2 == 1 ? "秋季学期" : "春季学期";
+        return $"{startYear}—{startYear + 1} 学年{season}";
+    }
+
+    private ActionResult ConflictProblem(string detail) =>
+        Conflict(new ProblemDetails
+        {
+            Title = "无法进行学业规划",
+            Detail = detail,
+            Status = StatusCodes.Status409Conflict
+        });
+
+    private sealed record GradeAttempt(
+        Guid CourseId,
+        decimal Credits,
+        decimal? TotalScore,
+        GradeExamStatus ExamStatus);
+
+    private sealed record CourseLabel(
+        Guid CourseId,
+        string CourseCode,
+        string CourseName);
+
+    private sealed record PlanningCourse(
+        Guid CourseId,
+        string CourseCode,
+        string CourseName,
+        decimal Credits,
+        int RecommendedSemester,
+        CurriculumCourseType Type,
+        string ModuleCode,
+        string ModuleName,
+        IReadOnlyList<CourseLabel> Prerequisites);
+
+    private sealed record PlanningContext(
+        Student Student,
+        CurriculumPlan Plan,
+        IReadOnlyList<PlanningCourse> Courses,
+        IReadOnlyDictionary<Guid, PlanningCourse> CourseById,
+        IReadOnlyList<AcademicPlanningCourseSnapshot> CourseSnapshots,
+        IReadOnlyDictionary<Guid, CourseLabel> AllCourseLabels,
+        IReadOnlySet<Guid> PassedCourseIds,
+        IReadOnlySet<Guid> InProgressCourseIds,
+        IReadOnlySet<Guid> FailedCourseIds,
+        IReadOnlyDictionary<Guid, StudentCourseProgressStatus> StatusByCourse,
+        decimal EarnedCredits,
+        int CurrentSemester,
+        int NextSemester);
+
+    private sealed record LoadResult(
+        PlanningContext? Context,
+        ActionResult? Error);
+}
+
+public sealed record AcademicPlanningRequest(
+    IReadOnlyCollection<AcademicPlanningTermRequest> Terms);
+
+public sealed record AcademicPlanningTermRequest(
+    [Range(1, 30)] int Semester,
+    IReadOnlyCollection<Guid> CourseIds);

src/Jiaowu.Api/Controllers/CoursesController.cs

@@ -84,6 +84,17 @@ public sealed class CoursesController(
                 x.Nature,
                 x.AssessmentMethod,
                 x.Description,
+                PrerequisiteCourseIds = x.Prerequisites
+                    .OrderBy(item => item.PrerequisiteCourse!.Code)
+                    .Select(item => item.PrerequisiteCourseId),
+                Prerequisites = x.Prerequisites
+                    .OrderBy(item => item.PrerequisiteCourse!.Code)
+                    .Select(item => new
+                    {
+                        item.PrerequisiteCourseId,
+                        item.PrerequisiteCourse!.Code,
+                        item.PrerequisiteCourse.Name
+                    }),
                 x.IsEnabled,
                 x.SortOrder,
                 x.CreatedAt,
@@ -146,9 +157,6 @@ public sealed class CoursesController(
         CourseRequest request,
         CancellationToken cancellationToken)
     {
-        var validation = await ValidateAsync(request, cancellationToken);
-        if (validation is not null) return validation;
-
         var entity = new Course
         {
             Code = request.Code.Trim(),
@@ -166,6 +174,16 @@ public sealed class CoursesController(
             IsEnabled = request.IsEnabled,
             SortOrder = request.SortOrder
         };
+        var validation = await ValidateAsync(entity.Id, request, cancellationToken);
+        if (validation is not null) return validation;
+
+        entity.Prerequisites = NormalizePrerequisiteIds(request)
+            .Select(prerequisiteId => new CoursePrerequisite
+            {
+                CourseId = entity.Id,
+                PrerequisiteCourseId = prerequisiteId
+            })
+            .ToList();
         db.Courses.Add(entity);
         return await SaveAsync(entity.Id, true, cancellationToken);
     }
@@ -177,10 +195,12 @@ public sealed class CoursesController(
         CourseRequest request,
         CancellationToken cancellationToken)
     {
-        var entity = await db.Courses.FindAsync([id], cancellationToken);
+        var entity = await db.Courses
+            .Include(x => x.Prerequisites)
+            .FirstOrDefaultAsync(x => x.Id == id, cancellationToken);
         if (entity is null) return NotFound();
         if (!CanManage(entity.CollegeId, entity.Nature)) return Forbid();
-        var validation = await ValidateAsync(request, cancellationToken);
+        var validation = await ValidateAsync(id, request, cancellationToken);
         if (validation is not null) return validation;
 
         entity.Code = request.Code.Trim();
@@ -197,6 +217,19 @@ public sealed class CoursesController(
         entity.Description = Normalize(request.Description);
         entity.IsEnabled = request.IsEnabled;
         entity.SortOrder = request.SortOrder;
+        var prerequisiteIds = NormalizePrerequisiteIds(request).ToHashSet();
+        db.CoursePrerequisites.RemoveRange(
+            entity.Prerequisites.Where(x =>
+                !prerequisiteIds.Contains(x.PrerequisiteCourseId)));
+        foreach (var prerequisiteId in prerequisiteIds.Except(
+                     entity.Prerequisites.Select(x => x.PrerequisiteCourseId)))
+        {
+            entity.Prerequisites.Add(new CoursePrerequisite
+            {
+                CourseId = entity.Id,
+                PrerequisiteCourseId = prerequisiteId
+            });
+        }
         return await SaveAsync(entity.Id, false, cancellationToken);
     }
 
@@ -212,6 +245,7 @@ public sealed class CoursesController(
     }
 
     private async Task<ActionResult?> ValidateAsync(
+        Guid courseId,
         CourseRequest request,
         CancellationToken cancellationToken)
     {
@@ -224,9 +258,62 @@ public sealed class CoursesController(
             return ValidationProblem("所选课程分类不存在或已停用。");
         if (request.LectureHours + request.PracticeHours > request.TotalHours)
             return ValidationProblem("讲授学时与实践学时之和不能超过总学时。");
+
+        var prerequisiteIds = NormalizePrerequisiteIds(request).ToArray();
+        if (prerequisiteIds.Contains(courseId))
+            return ValidationProblem("课程不能把自身设置为先修课程。");
+        var accessiblePrerequisiteCount = await ScopedCourses()
+            .CountAsync(x =>
+                prerequisiteIds.Contains(x.Id) &&
+                x.IsEnabled,
+                cancellationToken);
+        if (accessiblePrerequisiteCount != prerequisiteIds.Length)
+            return ValidationProblem("包含不存在、已停用或不在当前数据范围内的先修课程。");
+        if (await CreatesPrerequisiteCycleAsync(
+                courseId,
+                prerequisiteIds,
+                cancellationToken))
+            return ValidationProblem("先修关系不能形成循环依赖。");
         return null;
     }
 
+    private async Task<bool> CreatesPrerequisiteCycleAsync(
+        Guid courseId,
+        IReadOnlyCollection<Guid> prerequisiteIds,
+        CancellationToken cancellationToken)
+    {
+        if (prerequisiteIds.Count == 0) return false;
+
+        var edges = await db.CoursePrerequisites.AsNoTracking()
+            .Where(x => x.CourseId != courseId)
+            .Select(x => new { x.CourseId, x.PrerequisiteCourseId })
+            .ToListAsync(cancellationToken);
+        var prerequisitesByCourse = edges
+            .GroupBy(x => x.CourseId)
+            .ToDictionary(
+                group => group.Key,
+                group => group.Select(x => x.PrerequisiteCourseId).ToArray());
+
+        foreach (var prerequisiteId in prerequisiteIds)
+        {
+            var pending = new Stack<Guid>();
+            var visited = new HashSet<Guid>();
+            pending.Push(prerequisiteId);
+            while (pending.TryPop(out var candidate))
+            {
+                if (candidate == courseId) return true;
+                if (!visited.Add(candidate) ||
+                    !prerequisitesByCourse.TryGetValue(candidate, out var next))
+                    continue;
+                foreach (var item in next) pending.Push(item);
+            }
+        }
+        return false;
+    }
+
+    private static IEnumerable<Guid> NormalizePrerequisiteIds(CourseRequest request) =>
+        (request.PrerequisiteCourseIds ?? []).Distinct();
+
     private IQueryable<Course> ScopedCourses()
     {
         var scope = currentUserDataScope.Current;
@@ -307,4 +394,5 @@ public sealed record CourseRequest(
     AssessmentMethod AssessmentMethod,
     [MaxLength(1000)] string? Description,
     bool IsEnabled,
-    int SortOrder);
+    int SortOrder,
+    IReadOnlyCollection<Guid>? PrerequisiteCourseIds = null);

src/Jiaowu.Api/Domain/Academic/PeopleAndCourseEntities.cs

@@ -50,6 +50,16 @@ public sealed class Course : CatalogEntity
     public CourseNature Nature { get; set; }
     public AssessmentMethod AssessmentMethod { get; set; }
     public string? Description { get; set; }
+    public ICollection<CoursePrerequisite> Prerequisites { get; set; } = [];
+    public ICollection<CoursePrerequisite> RequiredByCourses { get; set; } = [];
+}
+
+public sealed class CoursePrerequisite : EntityBase
+{
+    public Guid CourseId { get; set; }
+    public Course? Course { get; set; }
+    public Guid PrerequisiteCourseId { get; set; }
+    public Course? PrerequisiteCourse { get; set; }
 }
 
 public sealed class CourseCategory : CatalogEntity