src/GmRelay.Web/Services/SessionService.cs

@@ -169,6 +169,39 @@ public sealed class SessionService(
             new { GroupId = groupId, OwnerRole = GroupManagerRoleExtensions.OwnerValue })).ToList();
     }
 
+    public async Task<List<PlayerAttendanceStats>> GetGroupAttendanceStatsAsync(Guid groupId)
+    {
+        await using var conn = await dataSource.OpenConnectionAsync();
+        return (await conn.QueryAsync<PlayerAttendanceStats>(
+            """
+            SELECT
+                p.id AS PlayerId,
+                p.display_name AS DisplayName,
+                p.telegram_username AS TelegramUsername,
+                COUNT(DISTINCT s.id) AS TotalSessions,
+                COUNT(DISTINCT CASE WHEN sp.rsvp_status = 'Confirmed' THEN s.id END) AS ConfirmedCount,
+                COUNT(DISTINCT CASE WHEN sp.rsvp_status = 'Declined' THEN s.id END) AS DeclinedCount,
+                COUNT(DISTINCT CASE WHEN sp.rsvp_status = 'Pending' THEN s.id END) AS NoResponseCount,
+                COUNT(DISTINCT CASE WHEN sp.registration_status = 'Waitlisted' THEN s.id END) AS WaitlistedCount,
+                COUNT(DISTINCT CASE WHEN s.status = 'Cancelled' AND sp.rsvp_status IN ('Confirmed','Declined') THEN s.id END) AS CancellationAffectedCount,
+                CASE WHEN COUNT(DISTINCT s.id) > 0
+                    THEN ROUND(
+                        COUNT(DISTINCT CASE WHEN sp.rsvp_status = 'Confirmed' THEN s.id END)
+                        * 100.0 / COUNT(DISTINCT s.id), 2)
+                    ELSE 0
+                END AS AttendanceRate
+            FROM players p
+            JOIN session_participants sp ON sp.player_id = p.id
+            JOIN sessions s ON s.id = sp.session_id
+            WHERE s.group_id = @GroupId
+              AND s.scheduled_at <= now()
+              AND sp.is_gm = false
+            GROUP BY p.id, p.display_name, p.telegram_username
+            ORDER BY AttendanceRate DESC, ConfirmedCount DESC
+            """,
+            new { GroupId = groupId })).ToList();
+    }
+
     public async Task AddGroupCoGmAsync(
         Guid groupId,
         long ownerTelegramId,