Implement post-resume synchronisation

Author: freyacodes

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

@@ -427,7 +427,31 @@ class LavalinkNode(
         lavalink.transferOrphansTo(this)
     }
 
+    internal fun synchronizeAfterResume() {
+        getPlayers().subscribe { players ->
+            val remoteGuildIds = players.map { it.guildId }
 
+            players.forEach { player ->
+                playerCache[player.guildId] = player
+
+                val link = lavalink.getLinkIfCached(player.guildId) ?: return@forEach
+                if (link.node != this) return@forEach
+
+                link.state = if (player.state.connected) {
+                    LinkState.CONNECTED
+                } else {
+                    LinkState.DISCONNECTED
+                }
+            }
+
+            val missingIds = playerCache.keys().toList() - remoteGuildIds.toSet()
+            missingIds.forEach { guildId ->
+                playerCache.remove(guildId)
+                val link = lavalink.getLinkIfCached(guildId) ?: return@forEach
+                if (link.node == this) link.state = LinkState.DISCONNECTED
+            }
+        }
+    }
 
     override fun equals(other: Any?): Boolean {
         if (this === other) return true

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

@@ -83,6 +83,8 @@ class LavalinkSocket(private val node: LavalinkNode) : WebSocketListener(), Clos
                     node.rest.getSession().subscribe { node.cachedSession = null }
                 }
 
+                node.synchronizeAfterResume()
+
                 // Move players from older, unavailable nodes to ourselves.
                 node.transferOrphansToSelf()
             }