Add ETA hysteresis to smooth fluctuations

- Added time_to_seconds() and seconds_to_time() helper functions
- Modified calculate_eta() to use hysteresis (70% last rsync ETA, 30% calculated)
- Static variable in parse_rsync_progress() stores last known rsync ETA
- At 0% progress: use last known ETA if available, otherwise N/A
- Prevents ETA from jumping wildly when rsync alternates between ETA and elapsed time
- Smooths out rounding errors at low percentages

emhttp/plugins/dynamix/nchan/file_manager

@@ -61,7 +61,21 @@ function mb_strimhalf($text, $width, $trim_marker = "") {
   return mb_substr($text, 0, $half) . $trim_marker . mb_substr($text, -1 - $half);
 }
 
-function calculate_eta($transferred, $percent, $speed) {
+function time_to_seconds($time_str) {
+  if (!preg_match('/^(\d+):(\d+):(\d+)$/', $time_str, $matches)) {
+    return null;
+  }
+  return intval($matches[1]) * 3600 + intval($matches[2]) * 60 + intval($matches[3]);
+}
+
+function seconds_to_time($seconds) {
+  $hours = intval($seconds / 3600);
+  $minutes = intval(($seconds % 3600) / 60);
+  $secs = $seconds % 60;
+  return sprintf("%d:%02d:%02d", $hours, $minutes, $secs);
+}
+
+function calculate_eta($transferred, $percent, $speed, $last_rsync_eta_seconds = null) {
   // Convert transferred size to bytes
   $multipliers = ['K' => 1024, 'M' => 1024*1024, 'G' => 1024*1024*1024, 'T' => 1024*1024*1024*1024];
   $transferred_bytes = floatval($transferred);
@@ -71,7 +85,7 @@ function calculate_eta($transferred, $percent, $speed) {
       break;
     }
   }
-  
+
   // Convert speed to bytes/sec
   $speed_bytes = floatval($speed);
   if (stripos($speed, 'kB/s') !== false) {
@@ -81,25 +95,40 @@ function calculate_eta($transferred, $percent, $speed) {
   } elseif (stripos($speed, 'GB/s') !== false) {
     $speed_bytes *= 1024 * 1024 * 1024;
   }
-  
+
   // Calculate total size from percent
   $percent_val = intval(str_replace('%', '', $percent));
+  
+  // At 0%, we cannot calculate ETA reliably from transferred/percent
+  // but we can use the last known rsync ETA if available
+  if ($percent_val == 0) {
+    if ($last_rsync_eta_seconds !== null && $last_rsync_eta_seconds > 0) {
+      return seconds_to_time($last_rsync_eta_seconds);
+    }
+    return "N/A";
+  }
+  
   if ($percent_val > 0 && $percent_val < 100 && $speed_bytes > 0) {
     $total_bytes = $transferred_bytes * 100 / $percent_val;
     $remaining_bytes = $total_bytes - $transferred_bytes;
-    $eta_seconds = intval($remaining_bytes / $speed_bytes);
+    $calculated_eta_seconds = intval($remaining_bytes / $speed_bytes);
     
-    // Format as HH:MM:SS
-    $hours = intval($eta_seconds / 3600);
-    $minutes = intval(($eta_seconds % 3600) / 60);
-    $seconds = $eta_seconds % 60;
-    return sprintf("%d:%02d:%02d", $hours, $minutes, $seconds);
+    // Apply hysteresis: blend with last known rsync ETA to smooth out fluctuations
+    if ($last_rsync_eta_seconds !== null && $last_rsync_eta_seconds > 0) {
+      // Weight: 70% last rsync ETA, 30% calculated ETA
+      $eta_seconds = intval($last_rsync_eta_seconds * 0.7 + $calculated_eta_seconds * 0.3);
+    } else {
+      $eta_seconds = $calculated_eta_seconds;
+    }
+
+    return seconds_to_time($eta_seconds);
   }
-  
+
   return "N/A";
 }
 
 function parse_rsync_progress($status, $action_label) {
+  static $last_rsync_eta_seconds = null;
 
   // initialize text array with action label
   $text[0] = $action_label . "... ";
@@ -118,14 +147,17 @@ function parse_rsync_progress($status, $action_label) {
       $percent = $parts[1];
       $speed = $parts[2];
       $time = $parts[3];
-      
+
       // Check if this is an ETA line or elapsed time line
       // ETA lines have only 4 parts, elapsed time lines have additional (xfr#...) info
       if (isset($parts[4])) {
-        // Calculate our own ETA from transferred size, percent, and speed
-        $time = calculate_eta($transferred, $percent, $speed);
+        // Elapsed time line - calculate our own ETA with hysteresis
+        $time = calculate_eta($transferred, $percent, $speed, $last_rsync_eta_seconds);
+      } else {
+        // ETA line from rsync - store it for hysteresis
+        $last_rsync_eta_seconds = time_to_seconds($time);
       }
-      
+
       $text[1] = _('Completed') . ": " . $percent . ",  " . _('Speed') . ": " . $speed . ",  " . _('ETA') . ": " . $time;
     }
   }