feat: invalidate top-picks on watchlist changes

internal/watchlist/service.go

@@ -14,22 +14,27 @@ import (
 type watchlistService struct {
 	repo        domain.WatchlistRepository
 	jikan       *jikan.Client
+	invalidator domain.RecommendationInvalidator
 }
 
-func NewWatchlistService(repo domain.WatchlistRepository, jikan *jikan.Client) domain.WatchlistService {
+func NewWatchlistService(repo domain.WatchlistRepository, jikan *jikan.Client, invalidator domain.RecommendationInvalidator) domain.WatchlistService {
-	return &watchlistService{repo: repo, jikan: jikan}
+	return &watchlistService{repo: repo, jikan: jikan, invalidator: invalidator}
 }
 
 func (s *watchlistService) UpdateEntry(ctx context.Context, userID string, animeID int64, status string) error {
-	anime, fetchErr := s.jikan.GetAnimeByID(ctx, int(animeID))
+	var anime jikan.Anime
+	var fetchErr error
+	if s.jikan != nil {
+		anime, fetchErr = s.jikan.GetAnimeByID(ctx, int(animeID))
+	}
 	if fetchErr != nil {
 		// still allow status updates for already-known anime rows
 		anime = jikan.Anime{}
 	}
 
-	return s.repo.InTx(ctx, func(txCtx context.Context, repo domain.WatchlistRepository) error {
+	if err := s.repo.InTx(ctx, func(txCtx context.Context, repo domain.WatchlistRepository) error {
 		_, err := repo.GetAnime(txCtx, animeID)
-		if err != nil && fetchErr == nil {
+		if err != nil && fetchErr == nil && anime.MalID > 0 {
 			durationSeconds := anime.DurationSeconds()
 			duration := sql.NullFloat64{Valid: durationSeconds > 0}
 			if duration.Valid {
@@ -65,14 +70,28 @@ func (s *watchlistService) UpdateEntry(ctx context.Context, userID string, anime
 			CurrentTimeSeconds: existing.CurrentTimeSeconds,
 		})
 		return err
-	})
+	}); err != nil {
+		return err
+	}
+	s.invalidateTopPicks(userID)
+	return nil
 }
 
 func (s *watchlistService) RemoveEntry(ctx context.Context, userID string, animeID int64) error {
-	return s.repo.DeleteWatchListEntry(ctx, db.DeleteWatchListEntryParams{
+	if err := s.repo.DeleteWatchListEntry(ctx, db.DeleteWatchListEntryParams{
 		UserID:  userID,
 		AnimeID: animeID,
-	})
+	}); err != nil {
+		return err
+	}
+	s.invalidateTopPicks(userID)
+	return nil
+}
+
+func (s *watchlistService) invalidateTopPicks(userID string) {
+	if s.invalidator != nil {
+		s.invalidator.InvalidateTopPicksForUser(userID)
+	}
 }
 
 func (s *watchlistService) GetWatchlist(ctx context.Context, userID string) ([]domain.UserWatchListRow, error) {

internal/watchlist/service_test.go

@@ -12,7 +12,7 @@ import (
 
 func TestWatchlistServiceGetWatchlistMap(t *testing.T) {
 	repo := &fakeWatchlistRepository{watchlistAnimeIDs: []int64{1, 3}}
-	svc := NewWatchlistService(repo, nil)
+	svc := NewWatchlistService(repo, nil, nil)
 
 	got, err := svc.GetWatchlistMap(context.Background(), "user-1", []int64{1, 2, 3})
 	if err != nil {
@@ -28,7 +28,7 @@ func TestWatchlistServiceGetWatchlistMap(t *testing.T) {
 
 func TestWatchlistServiceGetWatchlistMapSkipsEmptyInputs(t *testing.T) {
 	repo := &fakeWatchlistRepository{}
-	svc := NewWatchlistService(repo, nil)
+	svc := NewWatchlistService(repo, nil, nil)
 
 	got, err := svc.GetWatchlistMap(context.Background(), "", []int64{1})
 	if err != nil {
@@ -52,7 +52,7 @@ func TestWatchlistServiceGetWatchlistMapSkipsEmptyInputs(t *testing.T) {
 
 func TestWatchlistServiceDeleteContinueWatchingClearsProgressInTransaction(t *testing.T) {
 	repo := &fakeWatchlistRepository{}
-	svc := NewWatchlistService(repo, nil)
+	svc := NewWatchlistService(repo, nil, nil)
 
 	if err := svc.DeleteContinueWatching(context.Background(), "user-1", 12); err != nil {
 		t.Fatalf("DeleteContinueWatching: %v", err)
@@ -76,7 +76,7 @@ func TestWatchlistServiceDeleteContinueWatchingClearsProgressInTransaction(t *te
 
 func TestWatchlistServiceDeleteContinueWatchingStopsAfterDeleteError(t *testing.T) {
 	repo := &fakeWatchlistRepository{deleteContinueErr: errors.New("delete failed")}
-	svc := NewWatchlistService(repo, nil)
+	svc := NewWatchlistService(repo, nil, nil)
 
 	if err := svc.DeleteContinueWatching(context.Background(), "user-1", 12); err == nil || err.Error() != "delete failed" {
 		t.Fatalf("DeleteContinueWatching error = %v, want delete failed", err)
@@ -88,7 +88,8 @@ func TestWatchlistServiceDeleteContinueWatchingStopsAfterDeleteError(t *testing.
 
 func TestWatchlistServiceRemoveEntry(t *testing.T) {
 	repo := &fakeWatchlistRepository{}
-	svc := NewWatchlistService(repo, nil)
+	invalidator := &fakeRecommendationInvalidator{}
+	svc := NewWatchlistService(repo, nil, invalidator)
 
 	if err := svc.RemoveEntry(context.Background(), "user-1", 9); err != nil {
 		t.Fatalf("RemoveEntry: %v", err)
@@ -96,6 +97,22 @@ func TestWatchlistServiceRemoveEntry(t *testing.T) {
 	if repo.deletedWatchlist.UserID != "user-1" || repo.deletedWatchlist.AnimeID != 9 {
 		t.Fatalf("delete params = %#v", repo.deletedWatchlist)
 	}
+	if invalidator.userID != "user-1" {
+		t.Fatalf("invalidated user = %q, want user-1", invalidator.userID)
+	}
+}
+
+func TestWatchlistServiceUpdateEntryInvalidatesRecommendations(t *testing.T) {
+	repo := &fakeWatchlistRepository{}
+	invalidator := &fakeRecommendationInvalidator{}
+	svc := NewWatchlistService(repo, nil, invalidator)
+
+	if err := svc.UpdateEntry(context.Background(), "user-1", 9, "watching"); err != nil {
+		t.Fatalf("UpdateEntry: %v", err)
+	}
+	if invalidator.userID != "user-1" {
+		t.Fatalf("invalidated user = %q, want user-1", invalidator.userID)
+	}
 }
 
 type fakeWatchlistRepository struct {
@@ -110,6 +127,14 @@ type fakeWatchlistRepository struct {
 	deletedWatchlist   db.DeleteWatchListEntryParams
 }
 
+type fakeRecommendationInvalidator struct {
+	userID string
+}
+
+func (i *fakeRecommendationInvalidator) InvalidateTopPicksForUser(userID string) {
+	i.userID = userID
+}
+
 func (r *fakeWatchlistRepository) InTx(ctx context.Context, fn func(context.Context, domain.WatchlistRepository) error) error {
 	r.inTxCalled = true
 	return fn(ctx, r)