Reduced recommended anime function complexity

pages/recommended/bestgenres.go

@@ -0,0 +1,43 @@
+package recommended
+
+import (
+	"sort"
+
+	"github.com/animenotifier/arn"
+)
+
+// getBestGenres returns the most liked genres for the user's anime list.
+func getBestGenres(animeList *arn.AnimeList) []string {
+	genreItems := animeList.Genres()
+	genreAffinity := map[string]float64{}
+	bestGenres := []string{}
+
+	for genre, animeListItems := range genreItems {
+		affinity := 0.0
+
+		for _, item := range animeListItems {
+			if item.Status != arn.AnimeListStatusCompleted {
+				continue
+			}
+
+			if item.Rating.Overall != 0 {
+				affinity += item.Rating.Overall
+			} else {
+				affinity += 5.0
+			}
+		}
+
+		genreAffinity[genre] = affinity
+		bestGenres = append(bestGenres, genre)
+	}
+
+	sort.Slice(bestGenres, func(i, j int) bool {
+		return genreAffinity[bestGenres[i]] > genreAffinity[bestGenres[j]]
+	})
+
+	if len(bestGenres) > bestGenreCount {
+		bestGenres = bestGenres[:bestGenreCount]
+	}
+
+	return bestGenres
+}