Add filter for duplicate mappings

pages/editor/editor.pixy

@@ -40,6 +40,7 @@ component EditorTabs(url string, user *arn.User)
 			Tab("MAL", "arrows-h", "/editor/anime/mapping/mal" + user.Settings().Editor.Filter.Suffix())
 			Tab("Shoboi", "arrows-h", "/editor/anime/mapping/shoboi" + user.Settings().Editor.Filter.Suffix())
 			Tab("AniList", "arrows-h", "/editor/anime/mapping/anilist" + user.Settings().Editor.Filter.Suffix())
+			Tab("Duplicate", "exclamation-circle", "/editor/anime/mapping/duplicate" + user.Settings().Editor.Filter.Suffix())
 
 	if strings.Contains(url, "/editor/anime/image/")
 		.tabs

pages/editor/filteranime/duplicate-mapping.go

@@ -0,0 +1,30 @@
+package filteranime
+
+import (
+	"github.com/aerogo/aero"
+	"github.com/animenotifier/arn"
+)
+
+// DuplicateMappings ...
+func DuplicateMappings(ctx *aero.Context) string {
+	return editorList(
+		ctx,
+		"Anime with duplicate mappings",
+		func(anime *arn.Anime) bool {
+			all := map[string]bool{}
+
+			for _, mapping := range anime.Mappings {
+				_, exists := all[mapping.Service]
+
+				if exists {
+					return true
+				}
+
+				all[mapping.Service] = true
+			}
+
+			return false
+		},
+		nil,
+	)
+}