From c890bfd1c3bf520bb59365fc95de8ff37f8563ff Mon Sep 17 00:00:00 2001
From: zgaetano <zgaetano@wilddragon.net>
Date: Tue, 31 Mar 2026 15:29:58 -0400
Subject: [PATCH] Add backend/internal/moonlight/launcher.go

---
 backend/internal/moonlight/launcher.go | 85 ++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 backend/internal/moonlight/launcher.go

diff --git a/backend/internal/moonlight/launcher.go b/backend/internal/moonlight/launcher.go
new file mode 100644
index 0000000..f7e47c3
--- /dev/null
+++ b/backend/internal/moonlight/launcher.go
@@ -0,0 +1,85 @@
+// Package moonlight handles launching the Moonlight client.
+// It locates the Moonlight executable and launches a stream session
+// to a specific host and app.
+package moonlight
+
+import (
+	"fmt"
+	"os/exec"
+	"runtime"
+)
+
+// DefaultPaths are the well-known install locations per platform.
+var DefaultPaths = map[string][]string{
+	"windows": {
+		`C:\Program Files\Moonlight Game Streaming\Moonlight.exe`,
+		`C:\Program Files (x86)\Moonlight Game Streaming\Moonlight.exe`,
+	},
+	"darwin": {
+		"/Applications/Moonlight.app/Contents/MacOS/Moonlight",
+	},
+	"linux": {
+		"/usr/bin/moonlight",
+		"/usr/local/bin/moonlight",
+	},
+}
+
+// Launcher knows how to start Moonlight.
+type Launcher struct {
+	execPath string
+}
+
+// New creates a Launcher, auto-detecting the Moonlight binary.
+// Pass an empty string to use auto-detection.
+func New(overridePath string) (*Launcher, error) {
+	if overridePath != "" {
+		if path, err := exec.LookPath(overridePath); err == nil {
+			return &Launcher{execPath: path}, nil
+		}
+		return nil, fmt.Errorf("moonlight not found at %q", overridePath)
+	}
+
+	// Try PATH first
+	if path, err := exec.LookPath("moonlight"); err == nil {
+		return &Launcher{execPath: path}, nil
+	}
+
+	// Try well-known locations
+	for _, candidate := range DefaultPaths[runtime.GOOS] {
+		if path, err := exec.LookPath(candidate); err == nil {
+			return &Launcher{execPath: path}, nil
+		}
+	}
+
+	// Return a launcher even if not found — we'll surface the error at connect time
+	return &Launcher{}, nil
+}
+
+// ExecPath returns the resolved path to the Moonlight binary.
+func (l *Launcher) ExecPath() string {
+	return l.execPath
+}
+
+// Stream launches a Moonlight stream to the given host + app.
+// app is typically "Desktop" for a full desktop stream.
+func (l *Launcher) Stream(hostIP, app string) error {
+	if l.execPath == "" {
+		return fmt.Errorf("Moonlight executable not found — please install Moonlight or set MOONLIGHT_PATH")
+	}
+	// moonlight stream <host> <app>
+	cmd := exec.Command(l.execPath, "stream", hostIP, app)
+	cmd.Stdout = nil
+	cmd.Stderr = nil
+	return cmd.Start() // non-blocking — let Moonlight own its window
+}
+
+// Pair runs the Moonlight pairing flow for a host.
+func (l *Launcher) Pair(hostIP string) error {
+	if l.execPath == "" {
+		return fmt.Errorf("Moonlight executable not found")
+	}
+	cmd := exec.Command(l.execPath, "pair", hostIP)
+	cmd.Stdout = nil
+	cmd.Stderr = nil
+	return cmd.Start()
+}