feat: add PipeWire muter functionality and service files for Sendspin audio player

cmd/client/main.go

@@ -1,15 +1,18 @@
 package main
 
 import (
+	"context"
 	"flag"
 	"fmt"
 	"log"
 	"os"
 	"os/signal"
 	"path/filepath"
+	"strings"
 	"syscall"
 	"time"
 
+	"github.com/Sendspin/sendspin-go/pkg/discovery"
 	"github.com/Sendspin/sendspin-go/pkg/sendspin"
 
 	"rpi-sendspin/internal/pipewire"
@@ -21,6 +24,10 @@ func main() {
 	device := flag.String("device", "", "PipeWire sink node name (default: system default)")
 	listDevices := flag.Bool("list-devices", false, "list available PipeWire sinks and exit")
 	volume := flag.Int("volume", 80, "initial volume (0-100)")
+	mdnsPort := flag.Int("mdns-port", 8928, "port to advertise in mDNS (_sendspin._tcp)")
+	noMDNS := flag.Bool("no-mdns", false, "disable mDNS advertisement")
+	muteLoopback := flag.String("mute-loopback", "", "PipeWire node.name of a loopback to mute while streaming from --mute-server (requires --mute-server)")
+	muteServer := flag.String("mute-server", "", "server address that arms loopback muting; must match --server (requires --mute-loopback)")
 	flag.Parse()
 
 	if *listDevices {
@@ -51,8 +58,22 @@ func main() {
 		log.Fatalf("resolve client ID: %v", err)
 	}
 
+	if !*noMDNS {
+		disc := discovery.NewManager(discovery.Config{
+			ServiceName: *name,
+			Port:        *mdnsPort,
+		})
+		if err := disc.Advertise(); err != nil {
+			log.Printf("mdns advertise: %v", err)
+		} else {
+			defer disc.Stop()
+		}
+	}
+
 	output := pipewire.NewOutput(*device, *name)
 
+	muter := buildMuter(*server, *muteServer, *muteLoopback)
+
 	player, err := sendspin.NewPlayer(sendspin.PlayerConfig{
 		ServerAddr: *server,
 		PlayerName: *name,
@@ -70,6 +91,11 @@ func main() {
 				log.Printf("now playing: %s — %s", meta.Artist, meta.Title)
 			}
 		},
+		OnStateChange: func(s sendspin.PlayerState) {
+			if muter != nil {
+				muter.SetDesiredMute(s.State == "playing")
+			}
+		},
 		OnError: func(err error) {
 			log.Printf("error: %v", err)
 		},
@@ -77,6 +103,15 @@ func main() {
 	if err != nil {
 		log.Fatalf("create player: %v", err)
 	}
+	// LIFO: muter.Stop runs AFTER player.Close, so the player has stopped
+	// emitting "playing" state by the time we force the final unmute.
+	if muter != nil {
+		defer func() {
+			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+			defer cancel()
+			muter.Stop(ctx)
+		}()
+	}
 	defer player.Close()
 
 	if *device != "" {
@@ -109,6 +144,45 @@ func hostname() string {
 	return h
 }
 
+// buildMuter wires up the loopback muter when both --mute-loopback and
+// --mute-server are set AND --mute-server matches the configured --server.
+// Mismatches are intentional silent no-ops so the same config file can ship
+// to machines where the server happens to be different — only logged so
+// it's visible. Returns nil when muting is disabled.
+//
+// The address check is a startup-time string compare; mDNS rediscovery
+// during reconnect could in theory move the player to a different server,
+// but for the same-machine echo-cancel use case that's acceptable.
+func buildMuter(server, muteServer, muteLoopback string) *pipewire.Muter {
+	if muteLoopback == "" && muteServer == "" {
+		return nil
+	}
+	if muteLoopback == "" || muteServer == "" {
+		log.Printf("muter: --mute-loopback and --mute-server must be set together; loopback mute disabled")
+		return nil
+	}
+	if !sameServerAddr(server, muteServer) {
+		log.Printf("muter: --mute-server %q != --server %q; loopback mute disabled", muteServer, server)
+		return nil
+	}
+	log.Printf("muter: will mute PipeWire node %q while streaming from %s", muteLoopback, server)
+	return pipewire.NewMuter(muteLoopback)
+}
+
+// sameServerAddr normalizes two host[:port] strings for equality so
+// "localhost" and "localhost:8927" compare equal when 8927 is the default.
+func sameServerAddr(a, b string) bool {
+	const defaultPort = "8927"
+	norm := func(s string) string {
+		s = strings.TrimSpace(strings.ToLower(s))
+		if !strings.Contains(s, ":") {
+			s += ":" + defaultPort
+		}
+		return s
+	}
+	return norm(a) == norm(b)
+}
+
 func clientIDFile() string {
 	dir, err := os.UserConfigDir()
 	if err != nil {