Implement node auto switching

lavalink.go

@@ -19,8 +19,10 @@ type Lavalink struct {
 	shards string
 	userID string
 
-	nodes   []Node
+	nodes   []*Node
 	players map[string]*Player
+
+	BestNodeFunc func([]*Node) (*Node, error)
 }
 
 var (
@@ -38,17 +40,18 @@ func NewLavalink(shards string, userID string) *Lavalink {
 	return &Lavalink{
 		shards:  shards,
 		userID:  userID,
-		/*		nodes:   make([]Node, 1),*/
 		players: make(map[string]*Player),
+
+		BestNodeFunc: BestNodeByLoad,
 	}
 }
 
 // AddNodes adds a node to the Lavalink manager
 func (lavalink *Lavalink) AddNodes(nodeConfigs ...NodeConfig) error {
-	nodes := make([]Node, len(nodeConfigs))
+	nodes := make([]*Node, len(nodeConfigs))
 
 	for i, c := range nodeConfigs {
-		n := Node{
+		n := &Node{
 			config:  c,
 			manager: lavalink,
 		}
@@ -71,7 +74,7 @@ func (lavalink *Lavalink) AddNodes(nodeConfigs ...NodeConfig) error {
 func (lavalink *Lavalink) removeNode(node *Node) error {
 	idx := -1
 	for i, n := range lavalink.nodes {
-		if n == *node {
+		if n == node {
 			idx = i
 			break
 		}
@@ -82,6 +85,18 @@ func (lavalink *Lavalink) removeNode(node *Node) error {
 
 	node.stop()
 
+	for _, player := range lavalink.players {
+		if player.node == node {
+			n, err := lavalink.BestNode()
+
+			if err != nil {
+				continue
+			}
+
+			player.ChangeNode(n)
+		}
+	}
+
 	// temp var for easier reading
 	n := lavalink.nodes
 	z := len(n) - 1
@@ -99,11 +114,7 @@ func (lavalink *Lavalink) BestNode() (*Node, error) {
 		return nil, errNoNodes
 	}
 
-	sort.SliceStable(lavalink.nodes, func(i, j int) bool {
+	return lavalink.BestNodeFunc(lavalink.nodes)
-		return lavalink.nodes[i].load < lavalink.nodes[j].load
-	})
-
-	return &lavalink.nodes[0], nil
 }
 
 // GetPlayer gets a player for a guild
@@ -116,3 +127,11 @@ func (lavalink *Lavalink) GetPlayer(guild string) (*Player, error) {
 
 	return p, nil
 }
+
+func BestNodeByLoad(n []*Node) (*Node, error) {
+	sort.SliceStable(n, func(i, j int) bool {
+		return n[i].load < n[j].load
+	})
+
+	return n[0], nil
+}

node.go

@@ -188,6 +188,7 @@ func (node *Node) CreatePlayer(guildID string, sessionID string, event VoiceServ
 		node:                  node,
 		handler:               handler,
 		vol:                   100,
+		lastVoiceServerUpdate: event,
 	}
 
 	node.manager.players[guildID] = player

player.go

@@ -15,6 +15,7 @@ type Player struct {
 	manager               *Lavalink
 	node                  *Node
 	handler               EventHandler
+	lastVoiceServerUpdate VoiceServerUpdate
 }
 
 // GuildID returns this player's Guild ID
@@ -173,9 +174,17 @@ func (player *Player) Forward(sessionID string, event VoiceServerUpdate) error {
 		Event:     &event,
 	}
 
+	player.lastVoiceServerUpdate = event
+
 	return player.node.wsConn.WriteJSON(msg)
 }
 
+func (player *Player) ChangeNode(node *Node) error {
+	player.node = node
+
+	return player.PlayAt(player.track, player.position, 0)
+}
+
 // Destroy will destroy this player
 func (player *Player) Destroy() error {
 	msg := basicMessage{