progress: add format variants

for iterating over a single group, or iterating just on the group level

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>

src/backup/datastore.rs

@@ -795,6 +795,23 @@ impl StoreProgress {
 
 impl std::fmt::Display for StoreProgress {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.group_snapshots == 0 {
+            write!(
+                f,
+                "{:.2}% ({} of {} groups)",
+                self.percentage() * 100.0,
+                self.done_groups,
+                self.total_groups,
+            )
+        } else if self.total_groups == 1 {
+            write!(
+                f,
+                "{:.2}% ({} of {} snapshots)",
+                self.percentage() * 100.0,
+                self.done_snapshots,
+                self.group_snapshots,
+            )
+        } else {
             write!(
                 f,
                 "{:.2}% ({} of {} groups, {} of {} group snapshots)",
@@ -805,4 +822,5 @@ impl std::fmt::Display for StoreProgress {
                 self.group_snapshots,
             )
         }
+    }
 }