Channel events: check user ban status before trying to fetch them

Reduces 404s on channel create/update

Tasks/EventTasks.cs

@@ -5,11 +5,39 @@ public class EventTasks
         public static Dictionary<DateTime, ChannelCreatedEventArgs> PendingChannelCreateEvents = new();
         public static Dictionary<DateTime, ChannelUpdatedEventArgs> PendingChannelUpdateEvents = new();
         public static Dictionary<DateTime, ChannelDeletedEventArgs> PendingChannelDeleteEvents = new();
+
+        // populated in Channel Create & Update handlers to save API calls in IsMemberInServer method
+        private static List<MemberPunishment> CurrentBans = new();
+
+        // set to true if the last attempt to populate CurrentBans failed, to suppress warnings in case of repeated failures
+        private static bool LastBanListPopulationFailed = false;
 
         // todo(milkshake): combine create & update handlers to reduce duplicate code
         public static async Task<bool> HandlePendingChannelCreateEventsAsync()
         {
             bool success = false;
+
+            // populate CurrentBans list
+            try
+            {
+                Dictionary<string, MemberPunishment> bans = (await Program.db.HashGetAllAsync("bans")).ToDictionary(
+                    x => x.Name.ToString(),
+                    x => JsonConvert.DeserializeObject<MemberPunishment>(x.Value)
+                );
+
+                CurrentBans = bans.Values.ToList();
+
+                LastBanListPopulationFailed = false;
+            }
+            catch (Exception ex)
+            {
+                if (!LastBanListPopulationFailed)
+                    Program.discord.Logger.LogWarning(ex, "Failed to populate list of current bans during override persistence checks! This warning will be suppressed until the next success!");
+
+                // Since this is likely caused by corrupt or otherwise unreadable data in the db, set a flag so that this warning is not spammed
+                // The flag will be reset on the next successful attempt to populate the CurrentBans list
+                LastBanListPopulationFailed = true;
+            }
 
             try
             {
@@ -163,6 +191,28 @@ await Program.db.HashSetAsync("overrides",
         public static async Task<bool> HandlePendingChannelUpdateEventsAsync()
         {
             bool success = false;
+
+            // populate CurrentBans list
+            try
+            {
+                Dictionary<string, MemberPunishment> bans = (await Program.db.HashGetAllAsync("bans")).ToDictionary(
+                    x => x.Name.ToString(),
+                    x => JsonConvert.DeserializeObject<MemberPunishment>(x.Value)
+                );
+
+                CurrentBans = bans.Values.ToList();
+
+                LastBanListPopulationFailed = false;
+            }
+            catch (Exception ex)
+            {
+                if (!LastBanListPopulationFailed)
+                    Program.discord.Logger.LogWarning(ex, "Failed to populate list of current bans during override persistence checks! This warning will be suppressed until the next success!");
+
+                // Since this is likely caused by corrupt or otherwise unreadable data in the db, set a flag so that this warning is not spammed
+                // The flag will be reset on the next successful attempt to populate the CurrentBans list
+                LastBanListPopulationFailed = true;
+            }
 
             try
             {
@@ -405,7 +455,11 @@ private static async Task<bool> IsMemberInServer(ulong userId, DiscordGuild guil
             if (guild.Members.ContainsKey(userId))
                 return true;
 
-            // If the user isn't cached, try fetching them to confirm
+            // If the user isn't cached, maybe they are banned? Check before making any API calls.
+            if (CurrentBans.Any(b => b.MemberId == userId))
+                return false;
+
+            // If the user isn't cached or banned, try fetching them to confirm
             try
             {
                 await guild.GetMemberAsync(userId);