refactor(watchlist): sortEntries, null checks, and beginTx

internal/database/helpers.go

@@ -1,17 +1,43 @@
 package database
 
-import "database/sql"
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+)
+
+func NullStringOr(n sql.NullString, fallback string) string {
+	if n.Valid && n.String != "" {
+		return n.String
+	}
+	return fallback
+}
 
 func DisplayTitle(titleEnglish, titleJapanese sql.NullString, titleOriginal string) string {
-	if titleEnglish.Valid && titleEnglish.String != "" {
-		return titleEnglish.String
-	}
-	if titleJapanese.Valid && titleJapanese.String != "" {
-		return titleJapanese.String
-	}
-	return titleOriginal
+	return NullStringOr(titleEnglish, NullStringOr(titleJapanese, titleOriginal))
 }
 
 func (r GetUserWatchListRow) DisplayTitle() string {
 	return DisplayTitle(r.TitleEnglish, r.TitleJapanese, r.TitleOriginal)
 }
+
+func BoolPtr(b sql.NullBool) *bool {
+	if !b.Valid {
+		return nil
+	}
+	return &b.Bool
+}
+
+func BeginTx(ctx context.Context, db *sql.DB) (*Queries, *sql.Tx, error) {
+	if db == nil {
+		return nil, nil, errors.New("database unavailable")
+	}
+
+	tx, err := db.BeginTx(ctx, nil)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to begin transaction: %w", err)
+	}
+
+	return New(tx), tx, nil
+}

internal/features/watchlist/handler.go

@@ -5,7 +5,7 @@ import (
 	"errors"
 	"log"
 	"net/http"
-	"sort"
+	"slices"
 	"strconv"
 
 	"mal/internal/database"
@@ -122,20 +122,13 @@ func (h *Handler) HandleDeleteWatchlist(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	titleEnglish := ""
-	if anime.TitleEnglish.Valid {
-		titleEnglish = anime.TitleEnglish.String
-	}
-	titleJapanese := ""
-	if anime.TitleJapanese.Valid {
-		titleJapanese = anime.TitleJapanese.String
-	}
+	title := database.DisplayTitle(anime.TitleEnglish, anime.TitleJapanese, anime.TitleOriginal)
 	airing := false
 	if anime.Airing.Valid {
 		airing = anime.Airing.Bool
 	}
 
-	templates.WatchlistDropdown(int(animeID), anime.TitleOriginal, titleEnglish, titleJapanese, anime.ImageUrl, "", airing).Render(r.Context(), w)
+	templates.WatchlistDropdown(int(animeID), anime.TitleOriginal, title, "", anime.ImageUrl, "", airing).Render(r.Context(), w)
 }
 
 func (h *Handler) HandleGetWatchlist(w http.ResponseWriter, r *http.Request) {
@@ -301,26 +294,34 @@ func (h *Handler) HandleImportWatchlist(w http.ResponseWriter, r *http.Request)
 }
 
 func (h *Handler) sortEntries(entries []database.GetUserWatchListRow, sortBy, sortOrder string) {
-	var less func(int, int) bool
+	isAsc := sortOrder == "asc"
 
 	switch sortBy {
 	case "title":
-		less = func(i, j int) bool {
-			cmp := entries[i].TitleOriginal < entries[j].TitleOriginal
-			if sortOrder == "asc" {
-				return cmp
+		slices.SortFunc(entries, func(a, b database.GetUserWatchListRow) int {
+			if a.TitleOriginal < b.TitleOriginal {
+				return -1
 			}
-			return !cmp
+			if a.TitleOriginal > b.TitleOriginal {
+				return 1
+			}
+			return 0
+		})
+		if !isAsc {
+			slices.Reverse(entries)
 		}
-	default: // "date"
-		less = func(i, j int) bool {
-			cmp := entries[i].UpdatedAt.After(entries[j].UpdatedAt)
-			if sortOrder == "asc" {
-				return !cmp
+	case "date":
+		slices.SortFunc(entries, func(a, b database.GetUserWatchListRow) int {
+			if a.UpdatedAt.After(b.UpdatedAt) {
+				return -1
 			}
-			return cmp
+			if a.UpdatedAt.Before(b.UpdatedAt) {
+				return 1
+			}
+			return 0
+		})
+		if !isAsc {
+			slices.Reverse(entries)
 		}
 	}
-
-	sort.SliceStable(entries, less)
 }

internal/features/watchlist/service.go

@@ -152,13 +152,12 @@ func (s *Service) DeleteContinueWatching(ctx context.Context, userID string, ani
 		return s.db.SaveWatchProgress(ctx, clearProgress)
 	}
 
-	tx, err := s.sqlDB.BeginTx(ctx, nil)
+	txQueries, tx, err := database.BeginTx(ctx, s.sqlDB)
 	if err != nil {
 		return fmt.Errorf("failed to begin transaction: %w", err)
 	}
 	defer tx.Rollback()
 
-	txQueries := database.New(tx)
 	if err := txQueries.DeleteContinueWatchingEntry(ctx, params); err != nil {
 		return fmt.Errorf("failed to delete continue watching entry: %w", err)
 	}