Add tracking of Session state on update/connect

Author: freyacodes

src/main/kotlin/dev/arbjerg/lavalink/client/LavalinkNode.kt

@@ -44,6 +44,7 @@ class LavalinkNode(
     val name = nodeOptions.name
     val regionFilter = nodeOptions.regionFilter
     val password = nodeOptions.password
+    internal var cachedSession: Session? = null
 
     var sessionId: String? = nodeOptions.sessionId
         internal set
@@ -239,7 +240,9 @@ class LavalinkNode(
      * Enables resuming. This causes Lavalink to continue playing for [duration], during which
      *  we can reconnect without losing our session data. */
     fun enableResuming(timeout: Duration): Mono<Session> {
-        return rest.patchSession(Session(resuming = true, timeout.seconds))
+        return rest.patchSession(Session(resuming = true, timeout.seconds)).doOnSuccess {
+            cachedSession = it
+        }
     }
 
     /**
@@ -248,7 +251,9 @@ class LavalinkNode(
      * This is the default behavior, reversing calls to [enableResuming].
      */
     fun disableResuming(): Mono<Session> {
-        return rest.patchSession(Session(resuming = false, timeoutSeconds = 0))
+        return rest.patchSession(Session(resuming = false, timeoutSeconds = 0)).doOnSuccess {
+            cachedSession = it
+        }
     }
 
     /**

src/main/kotlin/dev/arbjerg/lavalink/internal/LavalinkRestClient.kt

@@ -76,6 +76,12 @@ class LavalinkRestClient(val node: LavalinkNode) {
         }.toMono()
     }
 
+    fun getSession(): Mono<Session> {
+        return newRequest {
+            path("/v4/sessions/${node.sessionId}")
+        }.toMono()
+    }
+
     /**
      * Make a request to the lavalink node. This is internal to keep it looking nice in kotlin. Java compatibility is in the node class.
      */

src/main/kotlin/dev/arbjerg/lavalink/internal/LavalinkSocket.kt

@@ -75,6 +75,13 @@ class LavalinkSocket(private val node: LavalinkNode) : WebSocketListener(), Clos
                         .subscribe()
                 }
 
+                if (!resumed) {
+                    node.cachedSession = null
+                }
+                if (node.cachedSession == null) {
+                    node.rest.getSession().subscribe { node.cachedSession = null }
+                }
+
                 // Move players from older, unavailable nodes to ourselves.
                 node.transferOrphansToSelf()
             }