feat: add address flags to both client and server (#7)

* feat(server): configure address via -addr flag

* feat(client): add required flag -remote

Author: utilyre

cmd/client/main.go

@@ -1,19 +1,35 @@
 package main
 
 import (
+	"flag"
+	"fmt"
 	"log/slog"
 	"multiplayer/internal/cli"
 	_ "multiplayer/internal/config"
 	"multiplayer/internal/game"
+	"os"
 
 	"github.com/hajimehoshi/ebiten/v2"
 )
 
+var remoteAddr string
+
+func init() {
+	flag.StringVar(&remoteAddr, "remote", "", "specify remote server address")
+	flag.Parse()
+
+	if remoteAddr == "" {
+		fmt.Fprintln(os.Stderr, "flag -remote is required")
+		flag.PrintDefaults()
+		os.Exit(1)
+	}
+}
+
 func main() {
 	ctx, cancel := cli.NewSignalContext()
 	defer cancel()
 
-	g, err := game.New(ctx, "127.0.0.1:3000")
+	g, err := game.New(ctx, remoteAddr)
 	if err != nil {
 		slog.Error("failed to initialize game", "error", err)
 		return

cmd/server/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"flag"
 	_ "image/png"
 	"log/slog"
 	"multiplayer/internal/cli"
@@ -10,11 +11,18 @@ import (
 	"github.com/hajimehoshi/ebiten/v2"
 )
 
+var localAddr string
+
+func init() {
+	flag.StringVar(&localAddr, "addr", "127.0.0.1:", "specify udp/mcp listener address")
+	flag.Parse()
+}
+
 func main() {
 	ctx, cancel := cli.NewSignalContext()
 	defer cancel()
 
-	sim, err := simulation.New(ctx, "127.0.0.1:3000")
+	sim, err := simulation.New(ctx, localAddr)
 	if err != nil {
 		slog.Error("failed to instantiate simulation", "error", err)
 		return

internal/simulation/simulation.go

@@ -29,6 +29,8 @@ func New(ctx context.Context, laddr string) (*Simulation, error) {
 	if err != nil {
 		return nil, err
 	}
+	slog.Info("bound udp/mcp listener", "address", ln.LocalAddr())
+
 	sess, err := ln.Accept(ctx)
 	if err != nil {
 		return nil, err