Log OAuth warning when using OAuth clients without token.

Author: devoxin

common/src/main/java/dev/lavalink/youtube/YoutubeAudioSourceManager.java

@@ -55,6 +55,8 @@ public class YoutubeAudioSourceManager implements AudioSourceManager {
         new Music(), new AndroidVr(), new Web(), new WebEmbedded()
     };
 
+    private static boolean loggedOauthClientNoAccountWarning = false;
+
     private static final String PROTOCOL_REGEX = "(?:http://|https://|)";
     private static final String DOMAIN_REGEX = "(?:www\\.|m\\.|music\\.|)youtube\\.com";
     private static final String SHORT_DOMAIN_REGEX = "(?:www\\.|)youtu\\.be";
@@ -229,6 +231,14 @@ protected AudioItem loadItemOnce(@NotNull AudioReference reference) {
                     continue;
                 }
 
+                boolean shouldLogOauthWarning = client.supportsOAuth() && !loggedOauthClientNoAccountWarning &&
+                    !oauth2Handler.hasAccessToken() && client.getOptions().getPlayback();
+
+                if (shouldLogOauthWarning) {
+                    loggedOauthClientNoAccountWarning = true;
+                    log.warn("!!! You are using an OAuth-enabled client without a valid OAuth token! This client may not play videos!");
+                }
+
                 log.debug("Attempting to load {} with client \"{}\"", reference.identifier, client.getIdentifier());
                 httpInterface.getContext().setAttribute(Client.OAUTH_CLIENT_ATTRIBUTE, client.supportsOAuth());
 

common/src/main/java/dev/lavalink/youtube/http/YoutubeOauth2Handler.java

@@ -69,6 +69,10 @@ public void setRefreshToken(@Nullable String refreshToken, boolean skipInitializ
         }
     }
 
+    public boolean hasAccessToken() {
+        return accessToken != null;
+    }
+
     public boolean shouldRefreshAccessToken() {
         return enabled && !DataFormatTools.isNullOrEmpty(refreshToken) && (DataFormatTools.isNullOrEmpty(accessToken) || System.currentTimeMillis() >= tokenExpires);
     }