(Lion): Update to account for current session.

Remove `time` pending and syncing logic.
Update `time` and `coins` to account for current session.
Add `Session.duration` for current session duration.
Add `Session.coins_earned` for current session coins.

bot/modules/study/tracking/session_tracker.py

@@ -128,8 +128,31 @@ class Session:
 
     @property
     def data(self):
+        """
+        Row of the `current_sessions` table corresponding to this session.
+        """
         return current_sessions.fetch(self.key)
 
+    @property
+    def duration(self):
+        """
+        Current duration of the session.
+        """
+        return (utc_now() - self.data.start_time).total_seconds()
+
+    @property
+    def coins_earned(self):
+        """
+        Number of coins earned so far.
+        """
+        data = self.data
+
+        coins = self.duration * data.hourly_coins
+        coins += data.live_duration * data.hourly_live_coins
+        if data.live_start:
+            coins += (utc_now() - data.live_start).total_seconds() * data.hourly_live_coins
+        return coins // 3600
+
     def activate(self):
         """
         Activate the study session.