Export last_interval to Python (#4365)

* Export last_interval to Python

* Add last_interval field to StatsRevlogEntry

* Implement last_interval_secs function

* Update last_interval field type in stats.proto

* Update last_interval to use last_interval_secs

proto/anki/stats.proto

@@ -37,6 +37,8 @@ message CardStatsResponse {
     uint32 ease = 5;
     float taken_secs = 6;
     optional cards.FsrsMemoryState memory_state = 7;
+    // seconds
+    uint32 last_interval = 8;
   }
   repeated StatsRevlogEntry revlog = 1;
   int64 card_id = 2;

rslib/src/revlog/mod.rs

@@ -85,6 +85,15 @@ impl RevlogEntry {
         .unwrap()
     }
 
+    pub(crate) fn last_interval_secs(&self) -> u32 {
+        u32::try_from(if self.last_interval > 0 {
+            self.last_interval.saturating_mul(86_400)
+        } else {
+            self.last_interval.saturating_mul(-1)
+        })
+        .unwrap()
+    }
+
     /// Returns true if this entry represents a reset operation.
     /// These entries are created when a card is reset using
     /// [`Collection::reschedule_cards_as_new`].

rslib/src/stats/card.rs

@@ -227,6 +227,7 @@ fn stats_revlog_entry(
         ease: entry.ease_factor,
         taken_secs: entry.taken_millis as f32 / 1000.,
         memory_state: None,
+        last_interval: entry.last_interval_secs(),
     }
 }