feat: fetch from REST instead of cache for cross-cluster lookups

Myriad/Extensions/PermissionExtensions.cs

@@ -59,14 +59,14 @@ public static class PermissionExtensions
     }
 
     public static PermissionSet EveryonePermissions(this Guild guild) =>
-        guild.Roles.FirstOrDefault(r => r.Id == guild.Id)?.Permissions ?? PermissionSet.Dm;
+        guild.Roles.FirstOrDefault(r => r.Id == guild.Id)!.Permissions;
 
-    public static async Task<PermissionSet> EveryonePermissions(this IDiscordCache cache, Channel channel)
+    public static PermissionSet EveryonePermissions(Guild guild, Channel channel)
     {
         if (channel.Type == Channel.ChannelType.Dm)
             return PermissionSet.Dm;
 
-        var defaultPermissions = (await cache.GetGuild(channel.GuildId!.Value)).EveryonePermissions();
+        var defaultPermissions = guild.EveryonePermissions();
         var overwrite = channel.PermissionOverwrites?.FirstOrDefault(r => r.Id == channel.GuildId);
         if (overwrite == null)
             return defaultPermissions;

PluralKit.Bot/CommandSystem/Context/ContextChecksExt.cs

@@ -81,7 +81,10 @@ public static class ContextChecksExt
     public static async Task<bool> CheckPermissionsInGuildChannel(this Context ctx, Channel channel,
                                                                   PermissionSet neededPerms)
     {
-        var guild = await ctx.Cache.GetGuild(channel.GuildId.Value);
+        // this is a quick hack, should probably do it properly eventually
+        var guild = await ctx.Cache.TryGetGuild(channel.GuildId.Value);
+        if (guild == null)
+            await ctx.Rest.GetGuild(channel.GuildId.Value);
         if (guild == null)
             return false;
 

PluralKit.Bot/CommandSystem/Context/ContextEntityArgumentsExt.cs

@@ -151,7 +151,10 @@ public static class ContextEntityArgumentsExt
         if (!MentionUtils.TryParseChannel(ctx.PeekArgument(), out var id))
             return null;
 
-        if (!(await ctx.Cache.TryGetChannel(id) is Channel channel))
+        var channel = await ctx.Cache.TryGetChannel(id);
+        if (channel == null)
+            channel = await ctx.Rest.GetChannelOrNull(id);
+        if (channel == null)
             return null;
 
         if (!DiscordUtils.IsValidGuildChannel(channel))

PluralKit.Bot/Commands/Checks.cs

@@ -14,6 +14,7 @@ namespace PluralKit.Bot;
 public class Checks
 {
     private readonly BotConfig _botConfig;
+    // this must ONLY be used to get the bot's user ID
     private readonly IDiscordCache _cache;
     private readonly ProxyMatcher _matcher;
     private readonly ProxyService _proxy;
@@ -26,6 +27,7 @@ public class Checks
         PermissionSet.ManageWebhooks, PermissionSet.ReadMessageHistory
     };
 
+    // todo: make sure everything uses the minimum amount of REST calls necessary
     public Checks(DiscordApiClient rest, IDiscordCache cache, BotConfig botConfig, ProxyService proxy, ProxyMatcher matcher)
     {
         _rest = rest;
@@ -67,16 +69,17 @@ public class Checks
                 throw Errors.GuildNotFound(guildId);
         }
 
+        var guildMember = await _rest.GetGuildMember(guild.Id, await _cache.GetOwnUser());
+
         // Loop through every channel and group them by sets of permissions missing
         var permissionsMissing = new Dictionary<ulong, List<Channel>>();
         var hiddenChannels = false;
         var missingEmojiPermissions = false;
         foreach (var channel in await _rest.GetGuildChannels(guild.Id))
         {
-            var botPermissions = await _cache.PermissionsIn(channel.Id);
+            var botPermissions = PermissionExtensions.PermissionsFor(guild, channel, await _cache.GetOwnUser(), guildMember);
-            var webhookPermissions = await _cache.EveryonePermissions(channel);
+            var webhookPermissions = PermissionExtensions.EveryonePermissions(guild, channel);
-            var userPermissions =
+            var userPermissions = PermissionExtensions.PermissionsFor(guild, channel, ctx.Author.Id, senderGuildUser);
-                PermissionExtensions.PermissionsFor(guild, channel, ctx.Author.Id, senderGuildUser);
 
             if ((userPermissions & PermissionSet.ViewChannel) == 0)
             {
@@ -153,15 +156,23 @@ public class Checks
             throw new PKSyntaxError("You need to specify a channel.");
 
         var error = "Channel not found or you do not have permissions to access it.";
+        
+        // todo: this breaks if channel is not in cache and bot does not have View Channel permissions
         var channel = await ctx.MatchChannel();
         if (channel == null || channel.GuildId == null)
             throw new PKError(error);
 
+        var guild = await _rest.GetGuildOrNull(channel.GuildId.Value);
+        if (guild == null)
+            throw new PKError(error);
+
+        var guildMember = await _rest.GetGuildMember(channel.GuildId.Value, await _cache.GetOwnUser());
+
         if (!await ctx.CheckPermissionsInGuildChannel(channel, PermissionSet.ViewChannel))
             throw new PKError(error);
 
-        var botPermissions = await _cache.PermissionsIn(channel.Id);
+        var botPermissions = PermissionExtensions.PermissionsFor(guild, channel, await _cache.GetOwnUser(), guildMember);
-        var webhookPermissions = await _cache.EveryonePermissions(channel);
+        var webhookPermissions = PermissionExtensions.EveryonePermissions(guild, channel);
 
         // We use a bitfield so we can set individual permission bits
         ulong missingPermissions = 0;
@@ -240,7 +251,7 @@ public class Checks
             throw new PKError("You can only check your own messages.");
 
         // get the channel info
-        var channel = await _cache.GetChannel(channelId.Value);
+        var channel = await _rest.GetChannelOrNull(channelId.Value);
         if (channel == null)
             throw new PKError("Unable to get the channel associated with this message.");
 

PluralKit.Bot/Commands/Message.cs

@@ -20,7 +20,7 @@ namespace PluralKit.Bot;
 public class ProxiedMessage
 {
     private static readonly Duration EditTimeout = Duration.FromMinutes(10);
-    private readonly IDiscordCache _cache;
+    // private readonly IDiscordCache _cache;
     private readonly IClock _clock;
 
     private readonly EmbedService _embeds;
@@ -37,7 +37,7 @@ public class ProxiedMessage
         _rest = rest;
         _webhookExecutor = webhookExecutor;
         _logChannel = logChannel;
-        _cache = cache;
+        // _cache = cache;
     }
 
     public async Task EditMessage(Context ctx)
@@ -112,7 +112,7 @@ public class ProxiedMessage
             var error =
                 "The channel where the message was sent does not exist anymore, or you are missing permissions to access it.";
 
-            var channel = await _cache.GetChannel(msg.Message.Channel);
+            var channel = await _rest.GetChannelOrNull(msg.Message.Channel);
             if (channel == null)
                 throw new PKError(error);
 
@@ -165,7 +165,7 @@ public class ProxiedMessage
         var showContent = true;
         var noShowContentError = "Message deleted or inaccessible.";
 
-        var channel = await _cache.GetChannel(message.Message.Channel);
+        var channel = await _rest.GetChannelOrNull(message.Message.Channel);
         if (channel == null)
             showContent = false;
         else if (!await ctx.CheckPermissionsInGuildChannel(channel, PermissionSet.ViewChannel))
@@ -222,7 +222,7 @@ public class ProxiedMessage
 
         if (ctx.Match("author") || ctx.MatchFlag("author"))
         {
-            var user = await _cache.GetOrFetchUser(_rest, message.Message.Sender);
+            var user = await _rest.GetUser(message.Message.Sender);
             var eb = new EmbedBuilder()
                 .Author(new Embed.EmbedAuthor(
                     user != null

PluralKit.Bot/Services/LogChannelService.cs

@@ -81,24 +81,42 @@ public class LogChannelService
         if (logChannel == null || logChannel.Type != Channel.ChannelType.GuildText) return null;
 
         // Check bot permissions
-        var perms = await _cache.PermissionsIn(logChannel.Id);
+        var perms = await GetPermissionsInLogChannel(logChannel);
         if (!perms.HasFlag(PermissionSet.SendMessages | PermissionSet.EmbedLinks))
         {
             _logger.Information(
                 "Does not have permission to log proxy, ignoring (channel: {ChannelId}, guild: {GuildId}, bot permissions: {BotPermissions})",
-                ctx.LogChannel.Value, trigger.GuildId!.Value, perms);
+                logChannel.Id, trigger.GuildId!.Value, perms);
             return null;
         }
 
         return logChannel.Id;
     }
 
+    // todo: move this somewhere else
+    private async Task<PermissionSet> GetPermissionsInLogChannel(Channel channel)
+    {
+        var guild = await _cache.TryGetGuild(channel.GuildId.Value);
+        if (guild == null)
+            guild = await _rest.GetGuild(channel.GuildId.Value);
+
+        var guildMember = await _cache.TryGetSelfMember(channel.GuildId.Value);
+        if (guildMember == null)
+            guildMember = await _rest.GetGuildMember(channel.GuildId.Value, await _cache.GetOwnUser());
+
+        var perms = PermissionExtensions.PermissionsFor(guild, channel, await _cache.GetOwnUser(), guildMember);
+        return perms;
+    }
+
     private async Task<Channel?> FindLogChannel(ulong guildId, ulong channelId)
     {
         // TODO: fetch it directly on cache miss?
         if (await _cache.TryGetChannel(channelId) is Channel channel)
             return channel;
 
+        if (await _rest.GetChannelOrNull(channelId) is Channel restChannel)
+            return restChannel;
+
         // Channel doesn't exist or we don't have permission to access it, let's remove it from the database too
         _logger.Warning(
             "Attempted to fetch missing log channel {LogChannel} for guild {Guild}, removing from database",

PluralKit.Bot/Utils/DiscordUtils.cs

@@ -49,6 +49,32 @@ public static class DiscordUtils
             await rest.CreateReaction(msg.ChannelId, msg.Id, new Emoji { Name = reaction });
     }
 
+    public static async Task<Guild?> GetGuildOrNull(this DiscordApiClient rest, ulong guildId)
+    {
+        try
+        {
+            return await rest.GetGuild(guildId);
+        }
+        catch (ForbiddenException)
+        {
+            // no permission, couldn't fetch, oh well
+            return null;
+        }
+    }
+
+    public static async Task<Channel?> GetChannelOrNull(this DiscordApiClient rest, ulong channelId)
+    {
+        try
+        {
+            return await rest.GetChannel(channelId);
+        }
+        catch (ForbiddenException)
+        {
+            // no permission, couldn't fetch, oh well
+            return null;
+        }
+    }
+
     public static async Task<Message?> GetMessageOrNull(this DiscordApiClient rest, ulong channelId,
                                                         ulong messageId)
     {