Update to 1.16.3 + add a few new event callbacks.

bot/event.go

@@ -8,7 +8,30 @@ import (
 	pk "github.com/Tnze/go-mc/net/packet"
 )
 
+type seenPacketFlags uint8
+
+// Valid seenPacketFlags values.
+const (
+	seenJoinGame seenPacketFlags = 1 << iota
+	seenServerDifficulty
+	seenPlayerAbilities
+	seenPlayerInventory
+	seenUpdateLight
+	seenChunkData
+	seenPlayerPositionAndLook
+	seenSpawnPos
+
+	// gameReadyMinPackets are the minimum set of packets that must be seen, for
+	// the GameReady callback to be invoked.
+	gameReadyMinPackets = seenJoinGame | seenChunkData | seenUpdateLight |
+		seenPlayerAbilities | seenPlayerInventory | seenServerDifficulty |
+		seenPlayerPositionAndLook | seenSpawnPos
+)
+
 type eventBroker struct {
+	seenPackets seenPacketFlags
+	isReady     bool
+
 	GameStart      func() error
 	ChatMsg        func(msg chat.Message, pos byte, sender uuid.UUID) error
 	Disconnect     func(reason chat.Message) error
@@ -28,7 +51,29 @@ type eventBroker struct {
 	WindowsItem       func(id byte, slots []entity.Slot) error
 	WindowsItemChange func(id byte, slotID int, slot entity.Slot) error
 
-	// ReceivePacket will be called when new packet arrive.
-	// Default handler will run only if pass == false.
+	// ServerDifficultyChange is called whenever the gamemode of the server changes.
+	// At time of writing (1.16.3), difficulty values of 0, 1, 2, and 3 correspond
+	// to peaceful, easy, normal, and hard respectively.
+	ServerDifficultyChange func(difficulty int) error
+
+	// GameReady is called after the client has joined the server and successfully
+	// received player state. Additionally, the server has begun sending world
+	// state (such as lighting and chunk information).
+	//
+	// Use this callback as a signal as to when your bot should start 'doing'
+	// things.
+	GameReady func() error
+
+	// ReceivePacket will be called when new packets arrive.
+	// The default handler will run only if pass == false.
 	ReceivePacket func(p pk.Packet) (pass bool, err error)
 }
+
+func (b *eventBroker) updateSeenPackets(f seenPacketFlags) error {
+	b.seenPackets |= f
+	if (^b.seenPackets)&gameReadyMinPackets == 0 && b.GameReady != nil && !b.isReady {
+		b.isReady = true
+		return b.GameReady()
+	}
+	return nil
+}