feat: support starting before the desktop session (#2)

Co-authored-by: Copilot <[email protected]>

Author: jialeicui

cmd/keyswift/main.go

@@ -8,6 +8,7 @@ import (
 	"os/signal"
 	"strings"
 	"syscall"
+	"time"
 
 	"github.com/jialeicui/golibevdev"
 	"github.com/samber/lo"
@@ -128,6 +129,32 @@ func main() {
 	sigChan := make(chan os.Signal, 1)
 	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
 
+	// Try to reconnect DBus in the background
+	go func() {
+		ticker := time.NewTicker(5 * time.Second)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-ticker.C:
+				if _, ok := windowMonitor.(*dbus.DegradedReceiver); ok {
+					slog.Info("Attempting to reconnect to DBus...")
+					newMonitor, err := dbus.New()
+					if err == nil {
+						slog.Info("Successfully reconnected to DBus")
+						windowMonitor = newMonitor
+						// Update bus manager's window monitor
+						busMgr.UpdateWindowMonitor(windowMonitor)
+						// success, break
+						return
+					}
+				}
+			case <-sigChan:
+				return
+			}
+		}
+	}()
+
 	go func() {
 		<-sigChan
 		slog.Info("Shutting down...")

pkg/bus/impl.go

@@ -111,3 +111,13 @@ func (m *Impl) SendKeys(keyCodes []keys.Key) {
 
 	slog.Debug("SendKeys done", "input", keyCodes)
 }
+
+func (m *Impl) UpdateWindowMonitor(windowInfo wininfo.WinGetter) {
+	m.windowInfo = windowInfo
+	if windowInfo != nil {
+		err := windowInfo.OnActiveWindowChange(m.handleWindowFocus)
+		if err != nil {
+			slog.Error("failed to register window focus handler", "error", err)
+		}
+	}
+}

pkg/wininfo/dbus/dbus.go

@@ -3,6 +3,10 @@ package dbus
 import (
 	"encoding/json"
 	"fmt"
+	"log/slog"
+	"os"
+	"path/filepath"
+	"strings"
 
 	"github.com/godbus/dbus/v5"
 	"github.com/godbus/dbus/v5/introspect"
@@ -61,7 +65,71 @@ func (r *Receiver) Close() {
 	r.conn.Close()
 }
 
+// getDBusAddress attempts to get the latest DBus address
+func getDBusAddress() (string, error) {
+	// 1. First try to get from environment variable
+	if addr := os.Getenv("DBUS_SESSION_BUS_ADDRESS"); addr != "" {
+		return addr, nil
+	}
+
+	// 2. Try to get from systemd user session
+	uid := os.Getuid()
+	systemdSocket := fmt.Sprintf("/run/user/%d/bus", uid)
+	if _, err := os.Stat(systemdSocket); err == nil {
+		return fmt.Sprintf("unix:path=%s", systemdSocket), nil
+	}
+
+	// 3. Try to get from session file
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", fmt.Errorf("failed to get home directory: %w", err)
+	}
+
+	// Get DISPLAY environment variable, use ":0" as default if not set
+	display := os.Getenv("DISPLAY")
+	if display == "" {
+		display = ":0"
+	}
+
+	// Try to get from session file
+	sessionFile := filepath.Join(home, ".dbus", "session-bus", display)
+	if _, err := os.Stat(sessionFile); err == nil {
+		content, err := os.ReadFile(sessionFile)
+		if err != nil {
+			return "", fmt.Errorf("failed to read session file: %w", err)
+		}
+
+		lines := strings.Split(string(content), "\n")
+		for _, line := range lines {
+			if strings.HasPrefix(line, "DBUS_SESSION_BUS_ADDRESS=") {
+				addr := strings.TrimPrefix(line, "DBUS_SESSION_BUS_ADDRESS=")
+				addr = strings.Trim(addr, "'\"")
+				return addr, nil
+			}
+		}
+	}
+
+	// 4. Try to get from XDG_RUNTIME_DIR
+	if runtimeDir := os.Getenv("XDG_RUNTIME_DIR"); runtimeDir != "" {
+		busPath := filepath.Join(runtimeDir, "bus")
+		if _, err := os.Stat(busPath); err == nil {
+			return fmt.Sprintf("unix:path=%s", busPath), nil
+		}
+	}
+
+	return "", fmt.Errorf("failed to find DBus address")
+}
+
 func (r *Receiver) setupDBus() error {
+	// Get the latest DBus address
+	addr, err := getDBusAddress()
+	if err != nil {
+		return fmt.Errorf("failed to get DBus address: %w", err)
+	}
+
+	// Set environment variable
+	os.Setenv("DBUS_SESSION_BUS_ADDRESS", addr)
+
 	conn, err := dbus.ConnectSessionBus()
 	if err != nil {
 		return err
@@ -109,7 +177,35 @@ func WithActiveWindowChangeCallback(callback wininfo.ActiveWindowChangeCallback)
 	}
 }
 
-func New(opt ...Option) (*Receiver, error) {
+// DegradedReceiver is a degraded mode implementation, used when DBus is unavailable
+type DegradedReceiver struct {
+	*options
+	current *wininfo.WinInfo
+}
+
+func (r *DegradedReceiver) UpdateActiveWindow(in string) *dbus.Error {
+	return nil
+}
+
+func (r *DegradedReceiver) GetActiveWindow() (*wininfo.WinInfo, error) {
+	if r.current == nil {
+		return nil, fmt.Errorf("no active window")
+	}
+	return r.current, nil
+}
+
+func (r *DegradedReceiver) Close() {
+    // Perform cleanup for DegradedReceiver
+    r.options = nil // Reset options to prevent further use
+    slog.Info("DegradedReceiver closed")
+}
+
+func (r *DegradedReceiver) OnActiveWindowChange(callback wininfo.ActiveWindowChangeCallback) error {
+	r.options.onChange = callback
+	return nil
+}
+
+func New(opt ...Option) (wininfo.WinGetter, error) {
 	r := &Receiver{
 		options: &options{},
 	}
@@ -120,7 +216,11 @@ func New(opt ...Option) (*Receiver, error) {
 
 	err := r.setupDBus()
 	if err != nil {
-		return nil, err
+		// If DBus connection fails, return degraded mode implementation
+		slog.Warn("Failed to connect to DBus, running in degraded mode", "error", err)
+		return &DegradedReceiver{
+			options: r.options,
+		}, nil
 	}
 
 	return r, nil

pkg/wininfo/wininfo.go

@@ -7,11 +7,13 @@ type WinGetter interface {
 	// The callback function will be called with the new active window information
 	// The function should return an error if it fails to register the callback
 	OnActiveWindowChange(ActiveWindowChangeCallback) error
+	// Close closes the window info service
+	Close()
 }
 
 type WinInfo struct {
 	Title string
 	Class string
 }
 
-type ActiveWindowChangeCallback func(*WinInfo)
+type ActiveWindowChangeCallback func(*WinInfo)