[client] UI refactor (#6069)

Refactor UI

---------

Co-authored-by: Eduard Gert <kontakt@eduardgert.de>
Co-authored-by: braginini <bangvalo@gmail.com>
Co-authored-by: Pascal Fischer <32096965+pascal-fischer@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: riccardom <riccardomanfrin@gmail.com>

client/ui/guilog/debuglog.go

@@ -0,0 +1,77 @@
+//go:build !android && !ios && !freebsd && !js
+
+// Package guilog manages gui-client.log, which follows the daemon's log level:
+// in debug/trace the GUI attaches a rotated file alongside the console so its
+// (and the React frontend's forwarded) output is captured for the debug bundle.
+package guilog
+
+import (
+	"sync"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/util"
+)
+
+// DebugLog attaches/detaches gui-client.log based on the daemon's log level,
+// fed via Apply. The file is left on disk for the debug bundle to collect.
+// Disabled (and never touches logging) when the user set --log-file explicitly.
+type DebugLog struct {
+	uiPath  string
+	enabled bool
+
+	mu     sync.Mutex
+	fileOn bool
+}
+
+// NewDebugLog builds the GUI debug log. enabled is false when the user passed
+// --log-file (manual override).
+func NewDebugLog(uiPath string, enabled bool) *DebugLog {
+	return &DebugLog{uiPath: uiPath, enabled: enabled}
+}
+
+// Path returns the GUI log path to register with the daemon, or "" when disabled
+// so the daemon won't collect a file the GUI never writes.
+func (d *DebugLog) Path() string {
+	if !d.enabled {
+		return ""
+	}
+	return d.uiPath
+}
+
+// Apply reacts to a daemon log level (the logrus name, e.g. "debug").
+// Idempotent via the fileOn guard, so the startup replay plus a racing
+// change-event are harmless.
+func (d *DebugLog) Apply(level string) {
+	if !d.enabled {
+		return
+	}
+
+	// Compared numerically so there are no hard-coded level-name literals.
+	lvl, err := log.ParseLevel(level)
+	if err != nil {
+		lvl = log.InfoLevel
+	}
+	debug := lvl >= log.DebugLevel
+
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	switch {
+	case debug && !d.fileOn:
+		if err := util.SetLogOutputs(log.StandardLogger(), util.LogConsole, d.uiPath); err != nil {
+			log.Errorf("attach GUI file log %s: %v", d.uiPath, err)
+			return
+		}
+		log.SetLevel(lvl)
+		d.fileOn = true
+		log.Infof("GUI file logging enabled (daemon level %s), writing to %s", level, d.uiPath)
+	case !debug && d.fileOn:
+		if err := util.SetLogOutputs(log.StandardLogger(), util.LogConsole); err != nil {
+			log.Errorf("detach GUI file log: %v", err)
+		}
+		log.SetLevel(log.InfoLevel)
+		d.fileOn = false
+		log.Infof("GUI file logging disabled (daemon level: %s)", level)
+	}
+}