调课

src/Jiaowu.Api/Controllers/CourseAdjustmentsController.cs

@@ -3,6 +3,8 @@ using Jiaowu.Api.Domain.Academic;
 using Jiaowu.Api.Domain.Identity;
 using Jiaowu.Api.Infrastructure.Auth;
 using Jiaowu.Api.Infrastructure.Persistence;
+using Jiaowu.Api.Infrastructure.Scheduling;
+using Jiaowu.Api.Infrastructure.Teaching;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.EntityFrameworkCore;
@@ -58,6 +60,114 @@ public sealed class CourseAdjustmentsController(
             .ToListAsync(cancellationToken));
     }
 
+    [HttpGet("tasks/{teachingTaskId:guid}/session-options")]
+    [Authorize(Roles = Applicants)]
+    public async Task<ActionResult> GetSessionOptions(
+        Guid teachingTaskId,
+        CancellationToken cancellationToken)
+    {
+        var task = await AccessibleTeachingTasks().AsNoTracking()
+            .Where(x =>
+                x.Id == teachingTaskId &&
+                x.Status == TeachingTaskStatus.Published)
+            .Select(x => new
+            {
+                x.Id,
+                x.TaskNumber,
+                CourseName = x.Course!.Name,
+                x.AcademicTermId,
+                TermStartDate = x.AcademicTerm!.StartDate,
+                TermEndDate = x.AcademicTerm.EndDate
+            })
+            .FirstOrDefaultAsync(cancellationToken);
+        if (task is null) return NotFound();
+
+        var entries = await db.ScheduleEntries.AsNoTracking()
+            .Where(x =>
+                x.TeachingTaskId == teachingTaskId &&
+                x.SchedulePlan!.Status == SchedulePlanStatus.Published)
+            .OrderBy(x => x.DayOfWeek)
+            .ThenBy(x => x.StartPeriod)
+            .Select(x => new
+            {
+                x.Id,
+                x.DayOfWeek,
+                x.StartPeriod,
+                x.PeriodCount,
+                x.StartWeek,
+                x.EndWeek,
+                x.WeekPattern,
+                x.ClassroomId,
+                ClassroomName = x.Classroom != null ? x.Classroom.Name : null,
+                BuildingName = x.Classroom != null ? x.Classroom.Building!.Name : null
+            })
+            .ToListAsync(cancellationToken);
+
+        var occupied = await db.CourseAdjustments.AsNoTracking()
+            .Where(x =>
+                x.TeachingTaskId == teachingTaskId &&
+                x.SourceScheduleEntryId != null &&
+                x.SourceWeek != null &&
+                (x.Status == CourseAdjustmentStatus.Submitted ||
+                 x.Status == CourseAdjustmentStatus.Approved))
+            .Select(x => new { x.SourceScheduleEntryId, x.SourceWeek })
+            .ToListAsync(cancellationToken);
+        var occupiedOccurrences = occupied
+            .Select(x => (x.SourceScheduleEntryId!.Value, x.SourceWeek!.Value))
+            .ToHashSet();
+
+        var sessions = entries
+            .SelectMany(entry => Enumerable.Range(
+                    entry.StartWeek,
+                    entry.EndWeek - entry.StartWeek + 1)
+                .Where(week => IncludesWeek(entry.WeekPattern, week))
+                .Select(week => new
+                {
+                    ScheduleEntryId = entry.Id,
+                    Week = week,
+                    Date = ResolveDate(task.TermStartDate, week, entry.DayOfWeek),
+                    entry.DayOfWeek,
+                    entry.StartPeriod,
+                    entry.PeriodCount,
+                    entry.ClassroomId,
+                    entry.ClassroomName,
+                    entry.BuildingName,
+                    HasExistingAdjustment = occupiedOccurrences.Contains((entry.Id, week))
+                }))
+            .Where(x => x.Date >= task.TermStartDate && x.Date <= task.TermEndDate)
+            .OrderBy(x => x.Date)
+            .ThenBy(x => x.StartPeriod)
+            .ToList();
+
+        var classrooms = await db.Classrooms.AsNoTracking()
+            .Where(x => x.IsEnabled)
+            .OrderBy(x => x.Building!.Campus!.SortOrder)
+            .ThenBy(x => x.Building!.SortOrder)
+            .ThenBy(x => x.SortOrder)
+            .Select(x => new
+            {
+                x.Id,
+                x.Name,
+                BuildingName = x.Building!.Name,
+                CampusName = x.Building.Campus!.Name,
+                x.Capacity
+            })
+            .ToListAsync(cancellationToken);
+        var periods = await db.ScheduleTimeSlots.AsNoTracking()
+            .Where(x => x.AcademicTermId == task.AcademicTermId && x.IsEnabled)
+            .OrderBy(x => x.PeriodNumber)
+            .Select(x => new
+            {
+                x.PeriodNumber,
+                x.Name,
+                StartsAt = x.StartsAt.ToString("HH:mm"),
+                EndsAt = x.EndsAt.ToString("HH:mm")
+            })
+            .ToListAsync(cancellationToken);
+
+        return Ok(new { Task = task, Sessions = sessions, Classrooms = classrooms, Periods = periods });
+    }
+
     // ═══════════════ My adjustments ═══════════════
 
     [HttpGet("mine")]
@@ -131,20 +241,41 @@ public sealed class CourseAdjustmentsController(
         var validation = await ValidateRequestAsync(request, cancellationToken);
         if (validation is not null) return validation;
 
+        var source = RequiresSourceOccurrence(request.Type)
+            ? await LoadSourceOccurrenceAsync(
+                request.TeachingTaskId,
+                request.SourceScheduleEntryId,
+                request.SourceWeek,
+                cancellationToken)
+            : null;
+        var targetDayOfWeek = request.TargetDate.HasValue
+            ? ToIsoDayOfWeek(request.TargetDate.Value.DayOfWeek)
+            : request.DayOfWeek;
+
         var adj = new CourseAdjustment
         {
             TeachingTaskId = request.TeachingTaskId,
             Type = request.Type,
             ApplicantUserId = userId,
             Reason = request.Reason.Trim(),
+            SourceScheduleEntryId = source?.Entry.Id,
+            SourceWeek = source?.Week,
+            SourceDate = source?.Date,
+            SourceStartPeriod = source?.Entry.StartPeriod,
+            SourcePeriodCount = source?.Entry.PeriodCount,
+            SourceClassroomId = source?.Entry.ClassroomId,
             TargetDate = request.TargetDate,
-            DayOfWeek = request.DayOfWeek,
+            DayOfWeek = targetDayOfWeek,
             StartPeriod = request.StartPeriod,
-            PeriodCount = request.PeriodCount,
+            PeriodCount = source?.Entry.PeriodCount ?? request.PeriodCount,
             ClassroomId = request.ClassroomId,
             SubstituteTeacherId = request.SubstituteTeacherId,
-            CancelWeek = request.CancelWeek,
-            CancelDate = request.CancelDate
+            CancelWeek = request.Type == CourseAdjustmentType.Cancel
+                ? source?.Week
+                : request.CancelWeek,
+            CancelDate = request.Type == CourseAdjustmentType.Cancel
+                ? source?.Date
+                : request.CancelDate
         };
 
         if (request.Submit)
@@ -193,6 +324,25 @@ public sealed class CourseAdjustmentsController(
         if (adj.Status != CourseAdjustmentStatus.Draft)
             return ConflictProblem("只有草稿可以提交。");
 
+        var validation = await ValidateRequestAsync(
+            new CourseAdjustmentRequest(
+                adj.TeachingTaskId,
+                adj.Type,
+                adj.Reason,
+                true,
+                adj.TargetDate,
+                adj.DayOfWeek,
+                adj.StartPeriod,
+                adj.PeriodCount,
+                adj.ClassroomId,
+                adj.SubstituteTeacherId,
+                adj.CancelWeek,
+                adj.CancelDate,
+                adj.SourceScheduleEntryId,
+                adj.SourceWeek),
+            cancellationToken);
+        if (validation is not null) return validation;
+
         adj.Status = CourseAdjustmentStatus.Submitted;
         adj.SubmittedAt = DateTime.UtcNow;
         await db.SaveChangesAsync(cancellationToken);
@@ -224,6 +374,12 @@ public sealed class CourseAdjustmentsController(
             .Include(x => x.TeachingTask)
             .ThenInclude(x => x!.Course)
             .ThenInclude(x => x!.College)
+            .Include(x => x.TeachingTask)
+            .ThenInclude(x => x!.Teachers)
+            .Include(x => x.TeachingTask)
+            .ThenInclude(x => x!.Classes)
+            .Include(x => x.TeachingTask)
+            .ThenInclude(x => x!.AcademicTerm)
             .FirstOrDefaultAsync(x => x.Id == id, cancellationToken);
         if (adj is null) return NotFound();
 
@@ -234,6 +390,12 @@ public sealed class CourseAdjustmentsController(
         if (adj.Status != CourseAdjustmentStatus.Submitted)
             return ConflictProblem("只有待审核的申请可以审批。");
 
+        var scheduleProblem = await ValidateApprovalScheduleAsync(
+            adj,
+            cancellationToken);
+        if (scheduleProblem is not null)
+            return ConflictProblem(scheduleProblem);
+
         adj.Status = CourseAdjustmentStatus.Approved;
         adj.ReviewedAt = DateTime.UtcNow;
         adj.ReviewedByUserId = currentUserDataScope.Current.UserId;
@@ -251,11 +413,9 @@ public sealed class CourseAdjustmentsController(
             NotificationCategory.Schedule);
 
         // Notify affected students
-        var studentUserIds = await db.CourseEnrollments
-            .Where(x =>
-                x.CourseSelectionOffering!.TeachingTaskId == adj.TeachingTaskId &&
-                x.Status == CourseEnrollmentStatus.Enrolled)
-            .Select(x => x.Student!.UserId)
+        var studentUserIds = await TeachingTaskRosterQuery
+            .ForTask(db, adj.TeachingTaskId)
+            .Select(x => x.UserId)
             .Where(uid => uid != null)
             .Select(uid => uid!.Value)
             .Distinct()
@@ -278,81 +438,19 @@ public sealed class CourseAdjustmentsController(
         switch (adj.Type)
         {
             case CourseAdjustmentType.Reschedule:
-                // Update existing schedule entries for this teaching task
-                if (adj.DayOfWeek.HasValue && adj.StartPeriod.HasValue)
-                {
-                    var entries = await db.ScheduleEntries
-                        .Where(x => x.TeachingTaskId == adj.TeachingTaskId)
-                        .ToListAsync(ct);
-                    foreach (var entry in entries)
-                    {
-                        entry.DayOfWeek = adj.DayOfWeek.Value;
-                        entry.StartPeriod = adj.StartPeriod.Value;
-                        entry.PeriodCount = adj.PeriodCount ?? entry.PeriodCount;
-                    }
-                    if (adj.ClassroomId.HasValue)
-                    {
-                        foreach (var entry in entries)
-                            entry.ClassroomId = adj.ClassroomId.Value;
-                    }
-                }
+                var rescheduleSource = await LoadSourceEntryAsync(adj, ct);
+                ExcludeWeek(rescheduleSource, adj.SourceWeek!.Value);
+                db.ScheduleEntries.Add(CreateTargetEntry(adj, rescheduleSource.SchedulePlanId));
                 break;
 
             case CourseAdjustmentType.Cancel:
-                // Cancel: remove schedule entries for the specified week
-                if (adj.CancelWeek.HasValue)
-                {
-                    var entries = await db.ScheduleEntries
-                        .Where(x => x.TeachingTaskId == adj.TeachingTaskId &&
-                                    x.StartWeek <= adj.CancelWeek.Value &&
-                                    x.EndWeek >= adj.CancelWeek.Value)
-                        .ToListAsync(ct);
-                    foreach (var entry in entries)
-                    {
-                        // Split the entry to exclude the cancelled week
-                        if (entry.StartWeek == adj.CancelWeek.Value &&
-                            entry.EndWeek == adj.CancelWeek.Value)
-                        {
-                            db.ScheduleEntries.Remove(entry);
-                        }
-                        else if (entry.StartWeek == adj.CancelWeek.Value)
-                        {
-                            entry.StartWeek = adj.CancelWeek.Value + 1;
-                        }
-                        else if (entry.EndWeek == adj.CancelWeek.Value)
-                        {
-                            entry.EndWeek = adj.CancelWeek.Value - 1;
-                        }
-                    }
-                }
+                var cancelSource = await LoadSourceEntryAsync(adj, ct);
+                ExcludeWeek(cancelSource, adj.SourceWeek!.Value);
                 break;
 
             case CourseAdjustmentType.Makeup:
-                // Makeup: add a temp schedule entry for the makeup date
-                if (adj.TargetDate.HasValue && adj.DayOfWeek.HasValue &&
-                    adj.StartPeriod.HasValue)
-                {
-                    var publishedPlan = await db.SchedulePlans
-                        .Where(x => x.AcademicTermId == adj.TeachingTask!.AcademicTermId &&
-                                    x.Status == SchedulePlanStatus.Published)
-                        .FirstOrDefaultAsync(ct);
-                    if (publishedPlan is not null)
-                    {
-                        db.ScheduleEntries.Add(new ScheduleEntry
-                        {
-                            SchedulePlanId = publishedPlan.Id,
-                            TeachingTaskId = adj.TeachingTaskId,
-                            ClassroomId = adj.ClassroomId,
-                            DayOfWeek = adj.DayOfWeek.Value,
-                            StartPeriod = adj.StartPeriod.Value,
-                            PeriodCount = adj.PeriodCount ?? 2,
-                            StartWeek = 1,
-                            EndWeek = 1,
-                            WeekPattern = WeekPattern.All,
-                            Notes = $"补课（原申请 {adj.CreatedAt:yyyy-MM-dd}）"
-                        });
-                    }
-                }
+                var makeupSource = await LoadSourceEntryAsync(adj, ct);
+                db.ScheduleEntries.Add(CreateTargetEntry(adj, makeupSource.SchedulePlanId));
                 break;
 
             case CourseAdjustmentType.Substitute:
@@ -442,15 +540,13 @@ public sealed class CourseAdjustmentsController(
         {
             case CourseAdjustmentType.Reschedule:
             case CourseAdjustmentType.Makeup:
-                if (!request.DayOfWeek.HasValue || request.DayOfWeek is < 1 or > 7)
-                    return ValidationProblem("请选择有效的上课日。");
+                if (!request.TargetDate.HasValue)
+                    return ValidationProblem(
+                        request.Type == CourseAdjustmentType.Reschedule
+                            ? "请选择调课后的日期。"
+                            : "请选择补课日期。");
                 if (!request.StartPeriod.HasValue || request.StartPeriod < 1)
                     return ValidationProblem("请选择起始节次。");
-                if (!request.PeriodCount.HasValue || request.PeriodCount < 1)
-                    return ValidationProblem("请选择持续节数。");
-                if (request.Type == CourseAdjustmentType.Makeup &&
-                    !request.TargetDate.HasValue)
-                    return ValidationProblem("补课必须指定日期。");
                 break;
             case CourseAdjustmentType.Substitute:
                 if (!request.SubstituteTeacherId.HasValue)
@@ -461,14 +557,226 @@ public sealed class CourseAdjustmentsController(
                     return ValidationProblem("代课教师不存在或已离职。");
                 break;
             case CourseAdjustmentType.Cancel:
-                if (!request.CancelWeek.HasValue && !request.CancelDate.HasValue)
-                    return ValidationProblem("停课需指定周次或日期。");
                 break;
         }
 
+        if (RequiresSourceOccurrence(request.Type))
+        {
+            var source = await LoadSourceOccurrenceAsync(
+                request.TeachingTaskId,
+                request.SourceScheduleEntryId,
+                request.SourceWeek,
+                cancellationToken);
+            if (source is null)
+                return ValidationProblem("请选择当前已发布课表中的具体原课次。");
+
+            var duplicate = await db.CourseAdjustments.AsNoTracking().AnyAsync(x =>
+                x.SourceScheduleEntryId == source.Entry.Id &&
+                x.SourceWeek == source.Week &&
+                (x.Status == CourseAdjustmentStatus.Submitted ||
+                 x.Status == CourseAdjustmentStatus.Approved),
+                cancellationToken);
+            if (duplicate)
+                return ConflictProblem("该课次已有待审核或已通过的调停课记录。");
+
+            if (request.TargetDate.HasValue &&
+                (request.TargetDate < source.Term.StartDate ||
+                 request.TargetDate > source.Term.EndDate))
+                return ValidationProblem("目标日期必须在本学期起止日期内。");
+        }
+
+        if (request.ClassroomId.HasValue &&
+            !await db.Classrooms.AsNoTracking().AnyAsync(x =>
+                x.Id == request.ClassroomId && x.IsEnabled,
+                cancellationToken))
+            return ValidationProblem("目标教室不存在或已停用。");
+
+        return null;
+    }
+
+    private async Task<string?> ValidateApprovalScheduleAsync(
+        CourseAdjustment adjustment,
+        CancellationToken cancellationToken)
+    {
+        if (!RequiresSourceOccurrence(adjustment.Type)) return null;
+
+        var source = await LoadSourceOccurrenceAsync(
+            adjustment.TeachingTaskId,
+            adjustment.SourceScheduleEntryId,
+            adjustment.SourceWeek,
+            cancellationToken);
+        if (source is null)
+            return "原课次已不在当前发布课表中，请退回后重新选择。";
+        if (adjustment.Type == CourseAdjustmentType.Cancel) return null;
+        if (!adjustment.TargetDate.HasValue || !adjustment.StartPeriod.HasValue)
+            return "目标上课日期或节次不完整。";
+
+        var targetWeek = ResolveWeek(source.Term.StartDate, adjustment.TargetDate.Value);
+        var targetDay = ToIsoDayOfWeek(adjustment.TargetDate.Value.DayOfWeek);
+        var target = new ScheduleEntry
+        {
+            TeachingTaskId = adjustment.TeachingTaskId,
+            TeachingTask = adjustment.TeachingTask,
+            ClassroomId = adjustment.ClassroomId ?? adjustment.SourceClassroomId,
+            DayOfWeek = targetDay,
+            StartPeriod = adjustment.StartPeriod.Value,
+            PeriodCount = adjustment.SourcePeriodCount ?? source.Entry.PeriodCount,
+            StartWeek = targetWeek,
+            EndWeek = targetWeek,
+            WeekPattern = WeekPattern.All
+        };
+        var possibleConflicts = await db.ScheduleEntries.AsNoTracking()
+            .Include(x => x.TeachingTask)
+            .ThenInclude(x => x!.Teachers)
+            .Include(x => x.TeachingTask)
+            .ThenInclude(x => x!.Classes)
+            .Where(x =>
+                x.SchedulePlan!.Status == SchedulePlanStatus.Published &&
+                x.Id != adjustment.SourceScheduleEntryId &&
+                x.DayOfWeek == targetDay &&
+                x.StartWeek <= targetWeek &&
+                x.EndWeek >= targetWeek &&
+                x.StartPeriod < target.StartPeriod + target.PeriodCount &&
+                target.StartPeriod < x.StartPeriod + x.PeriodCount)
+            .ToListAsync(cancellationToken);
+        foreach (var existing in possibleConflicts.Where(x =>
+                     IncludesWeek(x.WeekPattern, targetWeek)))
+        {
+            var reason = ScheduleConflictDetector.ConflictReason(target, existing);
+            if (reason is not null)
+                return $"目标时间存在{reason}冲突：{existing.TeachingTask!.Name}。";
+        }
+
         return null;
     }
 
+    private async Task<SourceOccurrence?> LoadSourceOccurrenceAsync(
+        Guid teachingTaskId,
+        Guid? scheduleEntryId,
+        int? week,
+        CancellationToken cancellationToken)
+    {
+        if (!scheduleEntryId.HasValue || !week.HasValue) return null;
+        var entry = await db.ScheduleEntries.AsNoTracking()
+            .Include(x => x.TeachingTask)
+            .ThenInclude(x => x!.AcademicTerm)
+            .FirstOrDefaultAsync(x =>
+                x.Id == scheduleEntryId.Value &&
+                x.TeachingTaskId == teachingTaskId &&
+                x.SchedulePlan!.Status == SchedulePlanStatus.Published,
+                cancellationToken);
+        if (entry?.TeachingTask?.AcademicTerm is null ||
+            week < entry.StartWeek || week > entry.EndWeek ||
+            !IncludesWeek(entry.WeekPattern, week.Value))
+            return null;
+        var date = ResolveDate(
+            entry.TeachingTask.AcademicTerm.StartDate,
+            week.Value,
+            entry.DayOfWeek);
+        if (date < entry.TeachingTask.AcademicTerm.StartDate ||
+            date > entry.TeachingTask.AcademicTerm.EndDate)
+            return null;
+        return new SourceOccurrence(
+            entry,
+            entry.TeachingTask.AcademicTerm,
+            week.Value,
+            date);
+    }
+
+    private Task<ScheduleEntry> LoadSourceEntryAsync(
+        CourseAdjustment adjustment,
+        CancellationToken cancellationToken) =>
+        db.ScheduleEntries.SingleAsync(x =>
+            x.Id == adjustment.SourceScheduleEntryId &&
+            x.TeachingTaskId == adjustment.TeachingTaskId &&
+            x.SchedulePlan!.Status == SchedulePlanStatus.Published,
+            cancellationToken);
+
+    private void ExcludeWeek(ScheduleEntry entry, int week)
+    {
+        db.ScheduleEntries.Remove(entry);
+        if (entry.StartWeek <= week - 1 &&
+            HasIncludedWeek(entry.WeekPattern, entry.StartWeek, week - 1))
+            db.ScheduleEntries.Add(CloneEntry(entry, entry.StartWeek, week - 1));
+        if (week + 1 <= entry.EndWeek &&
+            HasIncludedWeek(entry.WeekPattern, week + 1, entry.EndWeek))
+            db.ScheduleEntries.Add(CloneEntry(entry, week + 1, entry.EndWeek));
+    }
+
+    private ScheduleEntry CreateTargetEntry(
+        CourseAdjustment adjustment,
+        Guid schedulePlanId)
+    {
+        var targetWeek = ResolveWeek(
+            adjustment.TeachingTask!.AcademicTerm!.StartDate,
+            adjustment.TargetDate!.Value);
+        return new ScheduleEntry
+        {
+            SchedulePlanId = schedulePlanId,
+            TeachingTaskId = adjustment.TeachingTaskId,
+            ClassroomId = adjustment.ClassroomId ?? adjustment.SourceClassroomId,
+            DayOfWeek = ToIsoDayOfWeek(adjustment.TargetDate.Value.DayOfWeek),
+            StartPeriod = adjustment.StartPeriod!.Value,
+            PeriodCount = adjustment.SourcePeriodCount!.Value,
+            StartWeek = targetWeek,
+            EndWeek = targetWeek,
+            WeekPattern = WeekPattern.All,
+            Notes = adjustment.Type == CourseAdjustmentType.Reschedule
+                ? $"调课（原第 {adjustment.SourceWeek} 周）"
+                : $"补课（对应原第 {adjustment.SourceWeek} 周课次）"
+        };
+    }
+
+    private static ScheduleEntry CloneEntry(
+        ScheduleEntry source,
+        int startWeek,
+        int endWeek) => new()
+    {
+        SchedulePlanId = source.SchedulePlanId,
+        TeachingTaskId = source.TeachingTaskId,
+        ClassroomId = source.ClassroomId,
+        DayOfWeek = source.DayOfWeek,
+        StartPeriod = source.StartPeriod,
+        PeriodCount = source.PeriodCount,
+        StartWeek = startWeek,
+        EndWeek = endWeek,
+        WeekPattern = source.WeekPattern,
+        Notes = source.Notes
+    };
+
+    private static bool RequiresSourceOccurrence(CourseAdjustmentType type) =>
+        type is CourseAdjustmentType.Reschedule or
+            CourseAdjustmentType.Cancel or
+            CourseAdjustmentType.Makeup;
+
+    private static bool IncludesWeek(WeekPattern pattern, int week) =>
+        pattern == WeekPattern.All ||
+        pattern == WeekPattern.Odd && week % 2 == 1 ||
+        pattern == WeekPattern.Even && week % 2 == 0;
+
+    private static bool HasIncludedWeek(WeekPattern pattern, int startWeek, int endWeek) =>
+        Enumerable.Range(startWeek, endWeek - startWeek + 1)
+            .Any(week => IncludesWeek(pattern, week));
+
+    private static DateOnly ResolveDate(DateOnly termStartDate, int week, int dayOfWeek)
+    {
+        var startDay = (int)termStartDate.DayOfWeek;
+        var daysSinceMonday = (startDay + 6) % 7;
+        var firstWeekMonday = termStartDate.AddDays(-daysSinceMonday);
+        return firstWeekMonday.AddDays((week - 1) * 7 + dayOfWeek - 1);
+    }
+
+    private static int ResolveWeek(DateOnly termStartDate, DateOnly date)
+    {
+        var startDay = (int)termStartDate.DayOfWeek;
+        var daysSinceMonday = (startDay + 6) % 7;
+        var firstWeekMonday = termStartDate.AddDays(-daysSinceMonday);
+        return (date.DayNumber - firstWeekMonday.DayNumber) / 7 + 1;
+    }
+
+    private static int ToIsoDayOfWeek(DayOfWeek dayOfWeek) =>
+        dayOfWeek == System.DayOfWeek.Sunday ? 7 : (int)dayOfWeek;
+
     private IQueryable<TeachingTask> AccessibleTeachingTasks()
     {
         var source = db.TeachingTasks.AsQueryable();
@@ -483,7 +791,7 @@ public sealed class CourseAdjustmentsController(
         return source.Where(_ => false);
     }
 
-    private static System.Linq.Expressions.Expression<
+    private System.Linq.Expressions.Expression<
         Func<CourseAdjustment, object>> AdjustmentProjection() => x => new
     {
         x.Id,
@@ -500,6 +808,17 @@ public sealed class CourseAdjustmentsController(
         x.Status,
         x.Reason,
         x.ReviewComment,
+        x.SourceScheduleEntryId,
+        x.SourceWeek,
+        x.SourceDate,
+        x.SourceStartPeriod,
+        x.SourcePeriodCount,
+        SourceClassroomName = x.SourceClassroomId == null
+            ? null
+            : db.Classrooms
+                .Where(room => room.Id == x.SourceClassroomId)
+                .Select(room => room.Building!.Name + " " + room.Name)
+                .FirstOrDefault(),
         x.TargetDate,
         x.DayOfWeek,
         x.StartPeriod,
@@ -515,6 +834,12 @@ public sealed class CourseAdjustmentsController(
         x.CreatedAt
     };
 
+    private sealed record SourceOccurrence(
+        ScheduleEntry Entry,
+        AcademicTerm Term,
+        int Week,
+        DateOnly Date);
+
     private ActionResult ConflictProblem(string detail) =>
         Conflict(new ProblemDetails
         {
@@ -538,7 +863,9 @@ public sealed record CourseAdjustmentRequest(
     Guid? ClassroomId,
     Guid? SubstituteTeacherId,
     int? CancelWeek,
-    DateOnly? CancelDate);
+    DateOnly? CancelDate,
+    Guid? SourceScheduleEntryId = null,
+    int? SourceWeek = null);
 
 public sealed record RejectionRequest(
     [MaxLength(500)] string? Comment);