fix: improve subsonic client compatibility

internal/httpapi/router.go

@@ -5,9 +5,11 @@ import (
 	"encoding/json"
 	"errors"
 	"log"
+	"math/rand"
 	"net/http"
 	"os"
 	"path/filepath"
+	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -98,8 +100,10 @@ func NewRouter(cfg config.Config, database *sql.DB, scanService *scanner.Service
 			restGet(authed, "getSong", application.subsonicSongByID)
 			restGet(authed, "getRandomSongs", application.subsonicRandomSongs)
 			restGet(authed, "getAlbumList2", application.subsonicAlbumList2)
+			restGet(authed, "getSongsByGenre", application.subsonicSongsByGenre)
 			restGet(authed, "getMusicFolders", application.subsonicMusicFolders)
 			restGet(authed, "getGenres", application.subsonicGenres)
+			restGet(authed, "getOpenSubsonicExtensions", application.subsonicOpenSubsonicExtensions)
 			restGet(authed, "getPodcasts", application.subsonicPodcasts)
 			restGet(authed, "getNewestPodcasts", application.subsonicNewestPodcasts)
 			restGet(authed, "getInternetRadioStations", application.subsonicInternetRadioStations)
@@ -469,14 +473,63 @@ func (a app) subsonicAlbumList2(w http.ResponseWriter, r *http.Request) {
 			size = parsed
 		}
 	}
-	albums, err := a.library.Albums(r.Context(), size)
+	offset := parsePositiveInt(r.URL.Query().Get("offset"))
+	albums, err := a.library.Albums(r.Context(), 5000)
 	if err != nil {
 		writeJSON(w, http.StatusInternalServerError, subsonic.ErrorResponse(0, "failed to load albums"))
 		return
 	}
+	if genre := strings.TrimSpace(r.URL.Query().Get("genre")); genre != "" {
+		filtered := make([]library.Album, 0, len(albums))
+		for _, album := range albums {
+			if strings.EqualFold(strings.TrimSpace(album.Genre), genre) {
+				filtered = append(filtered, album)
+			}
+		}
+		albums = filtered
+	}
+	typeName := strings.ToLower(strings.TrimSpace(r.URL.Query().Get("type")))
+	switch typeName {
+	case "alphabeticalbyname":
+		sort.SliceStable(albums, func(i, j int) bool {
+			return strings.ToLower(albums[i].Title) < strings.ToLower(albums[j].Title)
+		})
+	case "random":
+		rand.Shuffle(len(albums), func(i, j int) {
+			albums[i], albums[j] = albums[j], albums[i]
+		})
+	default:
+		sort.SliceStable(albums, func(i, j int) bool {
+			return albums[i].Year > albums[j].Year
+		})
+	}
+	if offset > len(albums) {
+		albums = []library.Album{}
+	} else if offset > 0 {
+		albums = albums[offset:]
+	}
+	if size < len(albums) {
+		albums = albums[:size]
+	}
 	writeJSON(w, http.StatusOK, subsonic.AlbumList2Response(albums))
 }
 
+func (a app) subsonicSongsByGenre(w http.ResponseWriter, r *http.Request) {
+	genre := strings.TrimSpace(r.URL.Query().Get("genre"))
+	if genre == "" {
+		writeJSON(w, http.StatusBadRequest, subsonic.ErrorResponse(10, "missing genre"))
+		return
+	}
+	count := parsePositiveInt(r.URL.Query().Get("count"))
+	offset := parsePositiveInt(r.URL.Query().Get("offset"))
+	tracks, err := a.library.SongsByGenre(r.Context(), genre, count, offset)
+	if err != nil {
+		writeJSON(w, http.StatusInternalServerError, subsonic.ErrorResponse(0, "failed to load songs by genre"))
+		return
+	}
+	writeJSON(w, http.StatusOK, subsonic.SongsByGenreResponse(tracks))
+}
+
 func (a app) subsonicMusicFolders(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, subsonic.MusicFoldersResponse())
 }
@@ -502,6 +555,10 @@ func (a app) subsonicInternetRadioStations(w http.ResponseWriter, r *http.Reques
 	writeJSON(w, http.StatusOK, subsonic.InternetRadioStationsResponse())
 }
 
+func (a app) subsonicOpenSubsonicExtensions(w http.ResponseWriter, r *http.Request) {
+	writeJSON(w, http.StatusOK, subsonic.OpenSubsonicExtensionsResponse())
+}
+
 func (a app) subsonicSearch3(w http.ResponseWriter, r *http.Request) {
 	query := strings.TrimSpace(r.URL.Query().Get("query"))
 	if query == "" {