feat: implement listenbrainz /1/validate-token required for some clients (like pano scrobbler) to work

Signed-off-by: rooot <[e-mail]>

cmd/handlers.go

···
 	"strconv"
 
 	"github.com/teal-fm/piper/db"
+	"github.com/teal-fm/piper/db/apikey"
 	"github.com/teal-fm/piper/models"
 	atprotoauth "github.com/teal-fm/piper/oauth/atproto"
 	pages "github.com/teal-fm/piper/pages"
···
 		jsonResponse(w, http.StatusOK, response)
 	}
 }
+
+// apiMbTokenValidateHandler handles ListenBrainz token validation requests
+func apiMbTokenValidateHandler(sm *session.SessionManager) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		apiKeyStr, apiKeyErr := apikey.ExtractApiKey(r)
+
+		if apiKeyErr != nil || apiKeyStr == "" {
+			jsonResponse(w, http.StatusBadRequest, map[string]any{
+				"code":    400,
+				"message": "you need to specify a token",
+				"valid":   false,
+			})
+			return
+		}
+
+		key, valid := sm.ApiKeyMgr.GetApiKey(apiKeyStr)
+		if !valid {
+			jsonResponse(w, http.StatusUnauthorized, map[string]any{
+				"code":    401,
+				"message": "invalid token",
+				"valid":   false,
+			})
+			return
+		}
+
+		jsonResponse(w, http.StatusOK, map[string]any{
+			"code":      200,
+			"message":   "token valid",
+			"valid":     true,
+			"user_name": key.Name, // this is required to be set for pano scrobbler
+		})
+	}
+}

cmd/routes.go

···
 
 	// ListenBrainz-compatible endpoint
 	mux.HandleFunc("/1/submit-listens", session.WithAPIAuth(apiSubmitListensHandler(app.database, app.atprotoService, app.playingNowService, app.mbService), app.sessionManager))
+	mux.HandleFunc("/1/validate-token", apiMbTokenValidateHandler(app.sessionManager))
 
 	serverUrlRoot := viper.GetString("server.root_url")
 	atpClientId := viper.GetString("atproto.client_id")

session/session.go

···
 type SessionManager struct {
 	db        *db.DB
 	sessions  map[string]*Session // use in memory cache if necessary
-	apiKeyMgr *apikey.ApiKeyManager
+	ApiKeyMgr *apikey.ApiKeyManager
 	mu        sync.RWMutex
 }
 
···
 	return &SessionManager{
 		db:        database,
 		sessions:  make(map[string]*Session),
-		apiKeyMgr: apiKeyMgr,
+		ApiKeyMgr: apiKeyMgr,
 	}
 }
 
···
 }
 
 func (sm *SessionManager) GetAPIKeyManager() *apikey.ApiKeyManager {
-	return sm.apiKeyMgr
+	return sm.ApiKeyMgr
 }
 
 func (sm *SessionManager) CreateAPIKey(userID int64, name string, validityDays int) (*apikey.ApiKey, error) {
-	return sm.apiKeyMgr.CreateApiKey(userID, name, validityDays)
+	return sm.ApiKeyMgr.CreateApiKey(userID, name, validityDays)
 }
 
 // middleware that checks if a user is authenticated via cookies or API key
···
 		// first: check API keys
 		apiKeyStr, apiKeyErr := apikey.ExtractApiKey(r)
 		if apiKeyErr == nil && apiKeyStr != "" {
-			apiKey, valid := sm.apiKeyMgr.GetApiKey(apiKeyStr)
+			apiKey, valid := sm.ApiKeyMgr.GetApiKey(apiKeyStr)
 			if valid {
 				ctx := WithUserID(r.Context(), apiKey.UserID)
 				r = r.WithContext(ctx)
···
 
 		apiKeyStr, apiKeyErr := apikey.ExtractApiKey(r)
 		if apiKeyErr == nil && apiKeyStr != "" {
-			apiKey, valid := sm.apiKeyMgr.GetApiKey(apiKeyStr)
+			apiKey, valid := sm.ApiKeyMgr.GetApiKey(apiKeyStr)
 			if valid {
 				ctx = WithUserID(ctx, apiKey.UserID)
 				ctx = WithAPIRequest(ctx, true)
···
 			return
 		}
 
-		apiKey, valid := sm.apiKeyMgr.GetApiKey(apiKeyStr)
+		apiKey, valid := sm.ApiKeyMgr.GetApiKey(apiKeyStr)
 		if !valid {
 			w.Header().Set("Content-Type", "application/json")
 			w.WriteHeader(http.StatusUnauthorized)