From 21a63a43cca0a61d402561b2323d97647ce09273 Mon Sep 17 00:00:00 2001
From: rladenson <habonimkef@gmail.com>
Date: Mon, 25 Nov 2024 02:09:40 -0700
Subject: [PATCH] feat: decrement message counts on bulk message deletions

---
 PluralKit.Bot/Handlers/MessageDeleted.cs      | 21 +++++++++++++++++++
 .../Repository/ModelRepository.Member.cs      | 12 +++++------
 .../Repository/ModelRepository.Message.cs     |  3 +++
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/PluralKit.Bot/Handlers/MessageDeleted.cs b/PluralKit.Bot/Handlers/MessageDeleted.cs
index 65bf06a6..10788ebd 100644
--- a/PluralKit.Bot/Handlers/MessageDeleted.cs
+++ b/PluralKit.Bot/Handlers/MessageDeleted.cs
@@ -63,6 +63,27 @@ public class MessageDeleted: IEventHandler<MessageDeleteEvent>, IEventHandler<Me
             _logger.Information("Bulk deleting {Count} messages in channel {Channel}",
                 evt.Ids.Length, evt.ChannelId);
             await _repo.DeleteMessagesBulk(evt.Ids);
+
+            // get all the messages from the database
+            var messages = await _repo.GetMessagesBulk(evt.Ids);
+
+            // make a dictionary of every member id associated with a message and how many messages it's associated with
+            var memberMessageCounts = new Dictionary<MemberId, int>();
+            foreach (PKMessage msg in messages)
+            {
+                if (!msg.Member.HasValue) continue;
+                if (memberMessageCounts.ContainsKey(msg.Member.Value))
+                    memberMessageCounts[msg.Member.Value] = memberMessageCounts[msg.Member.Value] + 1;
+                else
+                    memberMessageCounts[msg.Member.Value] = 1;
+            }
+
+            // go through each member id in dictionary and decrement that member's message count by appropriate amount
+            foreach (MemberId member in memberMessageCounts.Keys)
+            {
+                await _repo.UpdateMemberForDeletedMessage(member, (await _repo.GetMember(member)).MessageCount, memberMessageCounts[member]);
+            }
+
         }
 
         _lastMessage.HandleMessageDeletion(evt.ChannelId, evt.Ids.ToList());
diff --git a/PluralKit.Core/Database/Repository/ModelRepository.Member.cs b/PluralKit.Core/Database/Repository/ModelRepository.Member.cs
index 16a59909..b3fa498a 100644
--- a/PluralKit.Core/Database/Repository/ModelRepository.Member.cs
+++ b/PluralKit.Core/Database/Repository/ModelRepository.Member.cs
@@ -111,21 +111,21 @@ public partial class ModelRepository
         await _db.ExecuteQuery(query);
     }
 
-    public async Task UpdateMemberForDeletedMessage(MemberId id, int msgCount)
+    public async Task UpdateMemberForDeletedMessage(MemberId id, int msgCount, int numberToDecrement = 1)
     {
         if (msgCount <= 0) return;
 
         var query = new Query("members")
-            .When(msgCount > 1,
-                // when there are plenty of messages
+            .When(msgCount > numberToDecrement,
+                // when message count is higher than number we're removing
                 q => q.AsUpdate(new
                 {
-                    message_count = new UnsafeLiteral("message_count - 1")
+                    message_count = new UnsafeLiteral($"message_count - {numberToDecrement}")
                 }),
-                // when this is the only message (if the db for some reason thinks there are no messages we already returned)
+                // when this is the only/last message(s) (if the db for some reason thinks there are no messages we already returned)
                 q => q.AsUpdate(new
                 {
-                    message_count = new UnsafeLiteral("message_count - 1"),
+                    message_count = 0,
                     last_message_timestamp = new UnsafeLiteral("null")
                 })
             )
diff --git a/PluralKit.Core/Database/Repository/ModelRepository.Message.cs b/PluralKit.Core/Database/Repository/ModelRepository.Message.cs
index 706e3a13..8a139283 100644
--- a/PluralKit.Core/Database/Repository/ModelRepository.Message.cs
+++ b/PluralKit.Core/Database/Repository/ModelRepository.Message.cs
@@ -26,6 +26,9 @@ public partial class ModelRepository
     public Task<PKMessage?> GetMessage(ulong id)
         => _db.QueryFirst<PKMessage?>(new Query("messages").Where("mid", id), messages: true);
 
+    public Task<IEnumerable<PKMessage>> GetMessagesBulk(IReadOnlyCollection<ulong> ids)
+        => _db.Query<PKMessage>(new Query("messages").WhereIn("mid", ids.Select(id => (long)id).ToArray()));
+
     public async Task<FullMessage?> GetFullMessage(ulong id)
     {
         var rawMessage = await GetMessage(id);