From 2f8a085adfb89ce696f6eb1212a63d9287da46fc Mon Sep 17 00:00:00 2001
From: Joseph-Ramos-CMU <jcramos@andrew.cmu.edu>
Date: Wed, 16 Dec 2020 12:04:07 -0500
Subject: [PATCH] Reworked reopening last tab to no longer use recursion

A reviewer of the pull request was concerned about recursion. I changed
the code to be iterative.
---
 osu.Game/Online/Chat/ChannelManager.cs | 56 ++++++++++++++++----------
 1 file changed, 35 insertions(+), 21 deletions(-)

diff --git a/osu.Game/Online/Chat/ChannelManager.cs b/osu.Game/Online/Chat/ChannelManager.cs
index 303696c294..1bbd2c3471 100644
--- a/osu.Game/Online/Chat/ChannelManager.cs
+++ b/osu.Game/Online/Chat/ChannelManager.cs
@@ -445,33 +445,47 @@ namespace osu.Game.Online.Chat
                 return;
             }
 
-            string lastClosedChannelName = closedChannels.Last();
-            closedChannels.RemoveAt(closedChannels.Count - 1);
-
-            // types did not work with existing enumerable interfaces funcitons like Contains
-            for (int i = 0; i < joinedChannels.Count; i++)
+            // This nested loop could be eliminated if a check was added so that
+            // when the code opens a channel it removes from the closedChannel list.
+            // However, this would require adding an O(|closeChannels|) work operation 
+            // every time the user joins a channel, which would make joining a channel
+            // slower. I wanted to centralize all major slowdowns so they
+            // can only occur if the user actually decides to use this feature.
+            for (int i = closedChannels.Count - 1; i >= 0; i--)
             {
-                // If the user already joined the channel, try the next
-                // channel in the list
-                if (joinedChannels[i].Name == lastClosedChannelName)
+                string lastClosedChannelName = closedChannels.Last();
+                closedChannels.RemoveAt(closedChannels.Count - 1);
+                bool alreadyJoined = false;
+                // If the user already joined the channel, do not
+                // try to join it
+                for (int j = 0; j < joinedChannels.Count; j++)
                 {
-                    JoinLastClosedChannel();
-                    return;
+                    if (joinedChannels[j].Name == lastClosedChannelName)
+                    {
+                        alreadyJoined = true;
+                        break;
+                    }
+                }
+
+                if (alreadyJoined == false)
+                {
+                    Channel lastClosedChannel = AvailableChannels.FirstOrDefault(c => c.Name == lastClosedChannelName);
+
+                    if (lastClosedChannel == null)
+                    {
+                        continue;
+                    }
+                    else
+                    {
+                        JoinChannel(lastClosedChannel);
+                        return;
+                    }
                 }
             }
-
-            Channel lastClosedChannel = AvailableChannels.FirstOrDefault(c => c.Name == lastClosedChannelName);
-
-            if (lastClosedChannel == null)
-            {
-                JoinLastClosedChannel();
-            }
-            else
-            {
-                JoinChannel(lastClosedChannel);
-            }
         }
 
+
+
         private long lastMessageId;
 
         private bool channelsInitialised;