feat: add initial code

cmd/urbanterror-agones/agones.go

@@ -0,0 +1,217 @@
+package main
+
+import (
+	"context"
+	"log/slog"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	sdk "agones.dev/agones/sdks/go"
+	q3c "bp99.eu/ut-agones/internal/quake3/client"
+)
+
+const (
+	checkInterval   = 5 * time.Second
+	playersListName = "players"
+)
+
+type sidecarState struct {
+	q3      *q3c.RobustQ3Client
+	sdk     *sdk.SDK
+	players map[string]q3c.Player
+}
+
+type agonesObserver struct {
+	id        string
+	state     *sidecarState
+	ctx       context.Context
+	firstPing bool
+}
+
+func (o *agonesObserver) Update(event string) {
+	slog.Debug("Got notification", "event", event)
+	switch event {
+	case q3c.PongEvent:
+		if o.firstPing {
+			slog.Debug("This is the first time gameserver was reached; reporting ready to Agones")
+			if err := o.state.sdk.Ready(); err != nil {
+				slog.Error("Failed to send ready signal to Agones", "error", err)
+			}
+			o.firstPing = false
+		} else {
+			slog.Debug("Sending health ping to Agones")
+			if err := o.state.sdk.Health(); err != nil {
+				slog.Error("Failed to send health ping to Agones", "error", err)
+			}
+		}
+	}
+}
+
+func (o *agonesObserver) GetID() string {
+	return o.id
+}
+
+func StartAgonesSidecar() error {
+	slog.Info("Starting Urban Terror Agones sidecar")
+
+	// Create context
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	// Create simple game client
+	client, err := q3c.New("localhost", 27960)
+	if err != nil {
+		slog.Error("Failed to create new Quake3 client", "error", err)
+		return err
+	}
+
+	// Create robust game client
+	robustClient := q3c.NewRobust(ctx, client)
+
+	// Initialize the Agones SDK
+	sdk, err := sdk.NewSDK()
+	if err != nil {
+		slog.Error("Failed to initialize Agones SDK", "error", err)
+		return err
+	}
+
+	// Set up SIGINT/SIGTERM handling
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+	go func() {
+		<-sigChan
+		slog.Info("Received shutdown signal")
+		cancel()
+	}()
+
+	// Keep state
+	state := &sidecarState{
+		q3:      robustClient,
+		sdk:     sdk,
+		players: make(map[string]q3c.Player, 0),
+	}
+
+	// Create and subscribe game client event observer
+	o := &agonesObserver{
+		id:        "agones",
+		state:     state,
+		ctx:       ctx,
+		firstPing: true,
+	}
+	robustClient.Subscribe(o)
+
+	// Start status check loop
+	go statusLoop(ctx, state)
+
+	// Keep alive
+	select {
+	case <-ctx.Done():
+		slog.Info("Shutting down Urban Terror Agones sidecar")
+	}
+
+	// Graceful shutdown
+	if err := state.q3.Stop(); err != nil {
+		slog.Error("Failed to gracefully Quake3 client", "error", err)
+		return err
+	}
+	return nil
+}
+
+func statusLoop(ctx context.Context, state *sidecarState) {
+	slog.Info("Starting status check loop", "interval", checkInterval)
+
+	ticker := time.NewTicker(checkInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			slog.Info("Exiting status check loop", "reason", "context cancelled")
+			return
+		case <-ticker.C:
+			slog.Debug("Tick; Retrieving gameserver status")
+			reportStatus(state)
+		}
+	}
+}
+
+func reportStatus(state *sidecarState) {
+	status, err := state.q3.GetStatus()
+	if err != nil {
+		slog.Error("Failed to get gameserer status from Quake3 client", "error", err)
+	}
+
+	if err := updatePlayersList(state, status.Players); err != nil {
+		slog.Error("Error while updating player list", "error", err)
+	}
+}
+
+func updatePlayersList(state *sidecarState, players []q3c.Player) error {
+	curPlayerMap := make(map[string]q3c.Player)
+	for _, p := range players {
+		curPlayerMap[p.Name] = p
+	}
+
+	// New and still connected players
+	for _, p := range players {
+		if _, exists := state.players[p.Name]; exists {
+			slog.Debug("Player already known to be online", "player", p.Name)
+		} else {
+			slog.Debug("Player joined", "player", p.Name)
+			if err := tryAppendToPlayerList(state.sdk, p.Name); err != nil {
+				return err
+			}
+			state.players[p.Name] = p
+		}
+	}
+
+	// Check for disconnected players
+	for name := range state.players {
+		if _, exists := curPlayerMap[name]; !exists {
+			slog.Debug("Player disconnected", "player", name)
+			if err := tryDeleteFromPlayerList(state.sdk, name); err != nil {
+				return err
+			}
+			delete(state.players, name)
+		}
+	}
+
+	slog.Debug("Updated players")
+	return nil
+}
+
+func tryAppendToPlayerList(sdk *sdk.SDK, player string) error {
+	exists, err := sdk.Beta().ListContains(playersListName, player)
+	if err != nil {
+		return err
+	}
+
+	if exists {
+		return nil
+	}
+
+	if err := sdk.Beta().AppendListValue(playersListName, player); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func tryDeleteFromPlayerList(sdk *sdk.SDK, player string) error {
+	exists, err := sdk.Beta().ListContains(playersListName, player)
+	if err != nil {
+		return err
+	}
+
+	if !exists {
+		return nil
+	}
+
+	if err := sdk.Beta().DeleteListValue(playersListName, player); err != nil {
+		return err
+	}
+
+	return nil
+}