test: add unit test for clamping logic in incremental indexing

internal/cron/incremental_indexing.go

@@ -129,9 +129,12 @@ func needsIncrementalIndexing(log *nginx_log.NginxLogWithIndex, persistence logI
 	// Fallback: use aggregated data cautiously by clamping the stored size so grouped entries
 	// do not trigger false positives when rotation files are aggregated together.
 	lastModified := time.Unix(log.LastModified, 0)
-	lastSize := log.LastSize
-	if lastSize == 0 || lastSize > fileSize {
-		lastSize = fileSize
+	rawLastSize := log.LastSize
+	clampedLastSize := rawLastSize
+	if clampedLastSize == 0 {
+		clampedLastSize = fileSize
+	} else if clampedLastSize > fileSize {
+		clampedLastSize = fileSize
 	}
 
 	// If the file was never indexed, queue it once.
@@ -139,15 +142,15 @@ func needsIncrementalIndexing(log *nginx_log.NginxLogWithIndex, persistence logI
 		return true
 	}
 
-	if fileModTime.After(lastModified) && fileSize > lastSize {
+	if fileModTime.After(lastModified) && fileSize > clampedLastSize {
 		logger.Debugf("File %s needs incremental indexing (fallback path): mod_time=%s, size=%d",
 			log.Path, fileModTime.Format("2006-01-02 15:04:05"), fileSize)
 		return true
 	}
 
-	if fileSize < lastSize {
-		logger.Debugf("File %s needs full re-indexing (fallback path) due to size decrease: old_size=%d, new_size=%d",
-			log.Path, lastSize, fileSize)
+	if fileSize < clampedLastSize {
+		logger.Debugf("File %s needs full re-indexing (fallback path) due to size decrease: old_size=%d (raw=%d), new_size=%d",
+			log.Path, clampedLastSize, rawLastSize, fileSize)
 		return true
 	}
 

internal/cron/incremental_indexing_test.go

@@ -11,6 +11,37 @@ import (
 	"github.com/0xJacky/Nginx-UI/model"
 )
 
+// Test that grouped (aggregated) log metadata with oversized LastSize values
+// does not incorrectly trigger rotation detection in the fallback path.
+func TestNeedsIncrementalIndexingAggregatedSizeRespectsClamp(t *testing.T) {
+	t.Parallel()
+
+	tmpDir := t.TempDir()
+	logPath := filepath.Join(tmpDir, "access.log")
+
+	if err := os.WriteFile(logPath, []byte("nginx-ui"), 0o644); err != nil {
+		t.Fatalf("failed to create temp log file: %v", err)
+	}
+
+	info, err := os.Stat(logPath)
+	if err != nil {
+		t.Fatalf("failed to stat temp log file: %v", err)
+	}
+
+	// Simulate aggregated metadata where LastSize is larger than the live file.
+	logEntry := &nginx_log.NginxLogWithIndex{
+		Path:         logPath,
+		Type:         "access",
+		LastModified: info.ModTime().Unix(),
+		LastIndexed:  time.Now().Unix(),
+		LastSize:     info.Size() * 5,
+	}
+
+	if needsIncrementalIndexing(logEntry, nil) {
+		t.Fatalf("aggregated size should not trigger re-indexing when clamped")
+	}
+}
+
 type stubLogIndexProvider struct {
 	idx *model.NginxLogIndex
 	err error