refactor: extract anime service layer and optimize API calls

api/anime/service.go

@@ -0,0 +1,138 @@
+package anime
+
+import (
+	"context"
+	"mal/integrations/jikan"
+	"mal/internal/db"
+
+	"golang.org/x/sync/errgroup"
+)
+
+type Service struct {
+	jikanClient *jikan.Client
+	db          database.Querier
+}
+
+func NewService(jikanClient *jikan.Client, db database.Querier) *Service {
+	return &Service{jikanClient: jikanClient, db: db}
+}
+
+func (s *Service) GetCatalogSection(ctx context.Context, userID string, section string) (map[string]any, error) {
+	var (
+		res       jikan.TopAnimeResult
+		cw        []database.GetContinueWatchingEntriesRow
+		watchlist []database.GetUserWatchListRow
+		err       error
+	)
+
+	g, gCtx := errgroup.WithContext(ctx)
+
+	g.Go(func() error {
+		switch section {
+		case "Airing":
+			res, err = s.jikanClient.GetSeasonsNow(gCtx, 1)
+		case "Popular":
+			res, err = s.jikanClient.GetTopAnime(gCtx, 1)
+		}
+		return err
+	})
+
+	if userID != "" {
+		g.Go(func() error {
+			if section == "Continue" {
+				var err error
+				cw, err = s.db.GetContinueWatchingEntries(gCtx, userID)
+				return err
+			}
+			return nil
+		})
+		g.Go(func() error {
+			var err error
+			watchlist, err = s.db.GetUserWatchList(gCtx, userID)
+			return err
+		})
+	}
+
+	if err := g.Wait(); err != nil {
+		return nil, err
+	}
+
+	animes := res.Animes
+	if len(animes) > 6 {
+		animes = animes[:6]
+	}
+
+	watchlistMap := make(map[int64]bool)
+	for _, entry := range watchlist {
+		watchlistMap[entry.AnimeID] = true
+	}
+
+	return map[string]any{
+		"Animes":           animes,
+		"ContinueWatching": cw,
+		"WatchlistMap":     watchlistMap,
+	}, nil
+}
+
+func (s *Service) GetDiscoverSection(ctx context.Context, userID string, section string) (map[string]any, error) {
+	var (
+		res       jikan.TopAnimeResult
+		watchlist []database.GetUserWatchListRow
+		err       error
+	)
+
+	g, gCtx := errgroup.WithContext(ctx)
+
+	g.Go(func() error {
+		switch section {
+		case "Trending":
+			res, err = s.jikanClient.GetSeasonsNow(gCtx, 1)
+		case "Upcoming":
+			res, err = s.jikanClient.GetSeasonsUpcoming(gCtx, 1)
+		case "Top":
+			res, err = s.jikanClient.GetTopAnime(gCtx, 1)
+		}
+		return err
+	})
+
+	if userID != "" {
+		g.Go(func() error {
+			var err error
+			watchlist, err = s.db.GetUserWatchList(gCtx, userID)
+			return err
+		})
+	}
+
+	if err := g.Wait(); err != nil {
+		return nil, err
+	}
+
+	animes := res.Animes
+	if len(animes) > 8 {
+		animes = animes[:8]
+	}
+
+	watchlistMap := make(map[int64]bool)
+	for _, entry := range watchlist {
+		watchlistMap[entry.AnimeID] = true
+	}
+
+	return map[string]any{
+		"Animes":       animes,
+		"WatchlistMap": watchlistMap,
+	}, nil
+}
+
+func (s *Service) filterUnique(animes []jikan.Anime, seen map[int]bool, limit int) []jikan.Anime {
+	unique := make([]jikan.Anime, 0)
+	for _, a := range animes {
+		if !seen[a.MalID] {
+			seen[a.MalID] = true
+			unique = append(unique, a)
+		}
+		if len(unique) >= limit {
+			break
+		}
+	}
+	return unique
+}