From 1bd203c5555046b7ee4fbfe2f822eb3d03571ad7 Mon Sep 17 00:00:00 2001
From: SergeiEU <39683682+SergeiEU@users.noreply.github.com>
Date: Wed, 1 Apr 2026 10:17:15 +0400
Subject: Initial import

---
 internal/engine/logger.go | 62 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 internal/engine/logger.go

(limited to 'internal/engine/logger.go')

diff --git a/internal/engine/logger.go b/internal/engine/logger.go
new file mode 100644
index 0000000..c448a56
--- /dev/null
+++ b/internal/engine/logger.go
@@ -0,0 +1,62 @@
+package engine
+
+import (
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+// RingLog keeps last N log lines in memory and optionally writes to file.
+type RingLog struct {
+	mu    sync.Mutex
+	lines []string
+	max   int
+	file  *os.File
+}
+
+// NewRingLog creates a ring buffer logger.
+func NewRingLog(maxLines int, dataDir string) *RingLog {
+	rl := &RingLog{
+		lines: make([]string, 0, maxLines),
+		max:   maxLines,
+	}
+	if dataDir != "" {
+		f, err := os.OpenFile(filepath.Join(dataDir, "vpnem.log"),
+			os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o644)
+		if err == nil {
+			rl.file = f
+		}
+	}
+	return rl
+}
+
+// Add appends a line.
+func (rl *RingLog) Add(line string) {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+
+	if len(rl.lines) >= rl.max {
+		rl.lines = rl.lines[1:]
+	}
+	rl.lines = append(rl.lines, line)
+
+	if rl.file != nil {
+		rl.file.WriteString(line + "\n")
+	}
+}
+
+// Lines returns all current lines.
+func (rl *RingLog) Lines() []string {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+	cp := make([]string, len(rl.lines))
+	copy(cp, rl.lines)
+	return cp
+}
+
+// Close closes the log file.
+func (rl *RingLog) Close() {
+	if rl.file != nil {
+		rl.file.Close()
+	}
+}
-- 
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