Update internal track cache on track start

Author: duncte123

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

@@ -12,7 +12,15 @@ interface IUpdatablePlayer {
      *
      * @return The updated builder, useful for chaining
      */
-    fun applyTrack(track: Track?): PlayerUpdateBuilder
+    fun setTrack(track: Track?): PlayerUpdateBuilder
+
+    @Deprecated(
+        message = "Use setTrack instead",
+        replaceWith = ReplaceWith("setTrack(track)")
+    )
+    fun applyTrack(track: Track?): PlayerUpdateBuilder {
+        return setTrack(track)
+    }
 
     /**
      * Shortcut for setting the encoded track to {@code null}. This will also clear the user data.

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

@@ -11,7 +11,8 @@ class LavalinkPlayer(private val node: LavalinkNode, protocolPlayer: Player) : I
      *
      * To get the current position of the track, use [position].
      */
-    val track = protocolPlayer.track
+    var track = protocolPlayer.track
+        internal set
 
     /**
      * Number between 0 and 1000, where 100 is 100% volume.
@@ -30,15 +31,16 @@ class LavalinkPlayer(private val node: LavalinkNode, protocolPlayer: Player) : I
 
     val position: Long
         get() {
+            val checkedTrack = track
             return when {
-                track == null -> 0
+                checkedTrack == null -> 0
                 paused -> state.position
-                else -> min(state.position + (System.currentTimeMillis() - state.time), track.info.length)
+                else -> min(state.position + (System.currentTimeMillis() - state.time), checkedTrack.info.length)
             }
         }
 
-    override fun applyTrack(track: Track?) = PlayerUpdateBuilder(node, guildId)
-        .applyTrack(track)
+    override fun setTrack(track: Track?) = PlayerUpdateBuilder(node, guildId)
+        .setTrack(track)
 
     override fun stopTrack() = PlayerUpdateBuilder(node, guildId)
         .stopTrack()

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

@@ -3,6 +3,7 @@ package dev.arbjerg.lavalink.client
 import dev.arbjerg.lavalink.internal.toLavalinkPlayer
 import dev.arbjerg.lavalink.protocol.v4.*
 import kotlinx.serialization.json.JsonObject
+import org.checkerframework.checker.optional.qual.Present
 import reactor.core.publisher.Mono
 import kotlin.math.max
 import kotlin.math.min
@@ -19,7 +20,7 @@ class PlayerUpdateBuilder internal constructor(private val node: LavalinkNode, p
     private var state: Omissible<VoiceState> = Omissible.omitted()
     private var noReplace = false
 
-    override fun applyTrack(track: Track?): PlayerUpdateBuilder {
+    override fun setTrack(track: Track?): PlayerUpdateBuilder {
         this.encodedTrack = Omissible.of(track?.encoded)
         this.trackUserData = track?.userData.toOmissible()
         return this
@@ -107,11 +108,14 @@ class PlayerUpdateBuilder internal constructor(private val node: LavalinkNode, p
 
     @Suppress("MemberVisibilityCanBePrivate")
     fun build() = PlayerUpdate(
-        track = PlayerUpdateTrack(
-            encodedTrack,
-            identifier,
-            trackUserData,
-        ).toOmissible(),
+        track = if (encodedTrack is Omissible.Present || identifier.isPresent())
+            PlayerUpdateTrack(
+                encodedTrack,
+                identifier,
+                trackUserData,
+            ).toOmissible()
+        else
+            Omissible.omitted(),
         position = position,
         endTime = endTime,
         volume = volume,

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

@@ -76,8 +76,14 @@ class LavalinkSocket(private val node: LavalinkNode) : WebSocketListener(), Clos
             }
 
             Message.Op.Event -> {
+                event as Message.EmittedEvent
+
+                if (event is Message.EmittedEvent.TrackStartEvent) {
+                    node.playerCache[event.guildId.toLong()]?.track = event.track
+                }
+
                 // TODO: handle websocket closed event from discord?
-                node.penalties.handleTrackEvent(event as Message.EmittedEvent)
+                node.penalties.handleTrackEvent(event)
             }
 
             else -> {