Implement block check within a precondition

With more preconditions in use, command logging has been modified to also be better able to respond to users in the event of an error. As a result, the bot is now able to respond to users and notify them properly if they fail any preconditions.

ApplicationCommands/BirthdayModule.cs

@@ -4,7 +4,7 @@ using System.Text;
 
 namespace BirthdayBot.ApplicationCommands;
 
-[RequireContext(ContextType.Guild)]
+[RequireGuildContext]
 [Group("birthday", HelpCmdBirthday)]
 public class BirthdayModule : BotModuleBase {
     public const string HelpCmdBirthday = "Commands relating to birthdays.";

ApplicationCommands/BirthdayOverrideModule.cs

@@ -3,7 +3,6 @@ using Discord.Interactions;
 
 namespace BirthdayBot.ApplicationCommands;
 
-[RequireContext(ContextType.Guild)]
 [RequireBotModerator]
 [Group("override", HelpCmdOverride)]
 public class BirthdayOverrideModule : BotModuleBase {

ApplicationCommands/BotModuleBase.cs

@@ -9,6 +9,7 @@ namespace BirthdayBot.ApplicationCommands;
 /// <summary>
 /// Base class for our interaction module classes. Contains common data for use in implementing classes.
 /// </summary>
+[EnforceBlocking]
 public abstract class BotModuleBase : InteractionModuleBase<SocketInteractionContext> {
     protected const string HelpPfxModOnly = "Bot moderators only: ";
     protected const string ErrGuildOnly = ":x: This command can only be run within a server.";

ApplicationCommands/ConfigModule.cs

@@ -4,7 +4,6 @@ using System.Text;
 
 namespace BirthdayBot.ApplicationCommands;
 
-[RequireContext(ContextType.Guild)]
 [RequireBotModerator]
 [Group("config", HelpCmdConfig)]
 public class ConfigModule : BotModuleBase {

ApplicationCommands/Preconditions/EnforceBlocking.cs

@@ -0,0 +1,38 @@
+using BirthdayBot.Data;
+using Discord.Interactions;
+
+namespace BirthdayBot.ApplicationCommands;
+
+/// <summary>
+/// Only users not on the blocklist or affected by moderator mode may use the command.<br/>
+/// This is used in the <see cref="BotModuleBase"/> base class. Manually using it anywhere else is unnecessary.
+/// </summary>
+class EnforceBlockingAttribute : PreconditionAttribute {
+    public const string FailModerated = "Guild has moderator mode enabled.";
+    public const string FailBlocked = "User is in the guild's block list.";
+    public const string ReplyModerated = ":x: This bot is in moderated mode, preventing you from using any bot commands in this server.";
+    public const string ReplyBlocked = ":x: You have been blocked from using bot commands in this server.";
+
+    public override async Task<PreconditionResult> CheckRequirementsAsync(
+        IInteractionContext context, ICommandInfo commandInfo, IServiceProvider services) {
+        // Not in guild context, unaffected by blocking
+        if (context.Guild is not SocketGuild guild) return PreconditionResult.FromSuccess();
+
+        // Manage Guild permission overrides any blocks
+        var user = (SocketGuildUser)context.User;
+        if (user.GuildPermissions.ManageGuild) return PreconditionResult.FromSuccess();
+
+        var gconf = await guild.GetConfigAsync().ConfigureAwait(false);
+
+        // Bot moderators override any blocks
+        if (gconf.ModeratorRole.HasValue && user.Roles.Any(r => r.Id == gconf.ModeratorRole.Value)) return PreconditionResult.FromSuccess();
+
+        // Moderated mode check
+        if (gconf.IsModerated) return PreconditionResult.FromError(FailModerated);
+
+        // Block list check
+        if (await gconf.IsUserInBlocklistAsync(user.Id)) return PreconditionResult.FromError(FailBlocked);
+
+        return PreconditionResult.FromSuccess();
+    }
+}

ApplicationCommands/Preconditions/RequireBotModerator.cs

@@ -3,29 +3,27 @@ using Discord.Interactions;
 
 namespace BirthdayBot.ApplicationCommands;
 
-// Contains preconditions used by our interaction modules.
-
 /// <summary>
-/// Precondition requiring the executing user be considered a bot moderator.
-/// That is, they must either have the Manage Server permission or be a member of the designated bot moderator role.
+/// Precondition requiring the executing user be recognized as a bot moderator.<br/>
+/// A bot moderator has either the Manage Server permission or is a member of the designated bot moderator role.
 /// </summary>
 class RequireBotModeratorAttribute : PreconditionAttribute {
-    public const string FailMsg = "User did not pass the mod check.";
+    public const string Error = "User did not pass the mod check.";
     public const string Reply = ":x: You must be a moderator to use this command.";
 
-    public override string ErrorMessage => FailMsg;
+    public override string ErrorMessage => Error;
 
     public override async Task<PreconditionResult> CheckRequirementsAsync(
         IInteractionContext context, ICommandInfo commandInfo, IServiceProvider services) {
-        if (context.User is not SocketGuildUser user) {
-            return PreconditionResult.FromError("Failed due to non-guild context.");
-        }
+        // A bot moderator can only exist in a guild context, so we must do this check.
+        // This check causes this precondition to become a functional equivalent to RequireGuildContextAttribute...
+        if (context.User is not SocketGuildUser user) return PreconditionResult.FromError(RequireGuildContextAttribute.Error);
 
         if (user.GuildPermissions.ManageGuild) return PreconditionResult.FromSuccess();
         var gconf = await ((SocketGuild)context.Guild).GetConfigAsync().ConfigureAwait(false);
         if (gconf.ModeratorRole.HasValue && user.Roles.Any(r => r.Id == gconf.ModeratorRole.Value))
             return PreconditionResult.FromSuccess();
 
-        return PreconditionResult.FromError(FailMsg);
+        return PreconditionResult.FromError(Error);
     }
-}
+}

ApplicationCommands/Preconditions/RequireGuildContext.cs

@@ -0,0 +1,16 @@
+using Discord.Interactions;
+
+namespace BirthdayBot.ApplicationCommands;
+
+/// <summary>
+/// Implements the included precondition from Discord.Net, requiring a guild context while using our custom error message.<br/><br/>
+/// Combining this with <see cref="RequireBotModeratorAttribute"/> is redundant. If possible, only use the latter instead.
+/// </summary>
+class RequireGuildContextAttribute : RequireContextAttribute {
+    public const string Error = "Command not received within a guild context.";
+    public const string Reply = ":x: This command is only available within a server.";
+
+    public override string ErrorMessage => Error;
+
+    public RequireGuildContextAttribute() : base(ContextType.Guild) { }
+}

BirthdayBot.csproj

@@ -5,7 +5,7 @@
     <TargetFramework>net6.0</TargetFramework>
 	<ImplicitUsings>enable</ImplicitUsings>
 	<Nullable>enable</Nullable>
-    <Version>3.3.0</Version>
+    <Version>3.3.1</Version>
     <Authors>NoiTheCat</Authors>
   </PropertyGroup>
 

Data/GuildConfiguration.cs

@@ -71,12 +71,19 @@ class GuildConfiguration {
     }
 
     /// <summary>
-    /// Checks if the given user exists in the block list.
-    /// If the server is in moderated mode, this always returns true.
+    /// Checks if the specified user is blocked by current guild policy (block list or moderated mode).
     /// </summary>
+    [Obsolete("Block lists should be reimplemented in a more resource-efficient manner later.", false)]
     public async Task<bool> IsUserBlockedAsync(ulong userId) {
         if (IsModerated) return true;
+        return await IsUserInBlocklistAsync(userId).ConfigureAwait(false);
+    }
 
+    /// <summary>
+    /// Checks if the given user exists in the block list.
+    /// </summary>
+    [Obsolete("Block lists should be reimplemented in a more resource-efficient manner later.", false)]
+    public async Task<bool> IsUserInBlocklistAsync(ulong userId) {
         using var db = await Database.OpenConnectionAsync().ConfigureAwait(false);
         using var c = db.CreateCommand();
         c.CommandText = $"select * from {BackingTableBans} "
@@ -92,6 +99,7 @@ class GuildConfiguration {
     /// <summary>
     /// Adds the specified user to the block list corresponding to this guild.
     /// </summary>
+    [Obsolete("Block lists will be reimplemented in a more practical manner later.", false)]
     public async Task BlockUserAsync(ulong userId) {
         using var db = await Database.OpenConnectionAsync().ConfigureAwait(false);
         using var c = db.CreateCommand();
@@ -109,6 +117,7 @@ class GuildConfiguration {
     /// Removes the specified user from the block list corresponding to this guild.
     /// </summary>
     /// <returns>True if a user has been removed, false if the requested user was not in this list.</returns>
+    [Obsolete("Block lists will be reimplemented in a more practical manner later.", false)]
     public async Task<bool> UnblockUserAsync(ulong userId) {
         using var db = await Database.OpenConnectionAsync().ConfigureAwait(false);
         using var c = db.CreateCommand();

ShardInstance.cs

@@ -170,26 +170,15 @@ public sealed class ShardInstance : IDisposable {
     private async Task DiscordClient_InteractionCreated(SocketInteraction arg) {
         var context = new SocketInteractionContext(DiscordClient, arg);
 
-        // Blocklist/moderated check
-        // TODO convert to precondition
-        var gconf = await GuildConfiguration.LoadAsync(context.Guild.Id, false);
-        if (context.Channel is SocketGuildChannel) { // Check only if in a guild context
-            if (!gconf!.IsBotModerator((SocketGuildUser)arg.User)) { // Moderators exempted from this check
-                if (await gconf.IsUserBlockedAsync(arg.User.Id)) {
-                    Log("Interaction", $"Interaction blocked per guild policy for {context.Guild}!{context.User}");
-                    await arg.RespondAsync(BotModuleBase.AccessDeniedError, ephemeral: true).ConfigureAwait(false);
-                    return;
-                }
-            }
-        }
-
         try {
             await _interactionService.ExecuteCommandAsync(context, _services).ConfigureAwait(false);
         } catch (Exception e) {
             Log(nameof(DiscordClient_InteractionCreated), $"Unhandled exception. {e}");
-            // TODO when implementing proper error logging, see here
-            if (arg.Type == InteractionType.ApplicationCommand)
-                if (arg.HasResponded) await arg.ModifyOriginalResponseAsync(prop => prop.Content = ":warning: An unknown error occured.");
+            // TODO when implementing proper application error logging, see here
+            if (arg.Type == InteractionType.ApplicationCommand) {
+                if (arg.HasResponded) await arg.ModifyOriginalResponseAsync(prop => prop.Content = InternalError);
+                else await arg.RespondAsync(InternalError);
+            }
         }
     }
 
@@ -205,17 +194,24 @@ public sealed class ShardInstance : IDisposable {
 
         if (result.Error != null) {
             // Additional log information with error detail
-            logresult += Enum.GetName(typeof(InteractionCommandError), result.Error) + ": " + result.ErrorReason;
+            logresult += " " + Enum.GetName(typeof(InteractionCommandError), result.Error) + ": " + result.ErrorReason;
 
             // Specific responses to errors, if necessary
-            if (result.Error == InteractionCommandError.UnmetPrecondition && result.ErrorReason == RequireBotModeratorAttribute.FailMsg) {
-                await context.Interaction.RespondAsync(RequireBotModeratorAttribute.Reply, ephemeral: true).ConfigureAwait(false);
+            if (result.Error == InteractionCommandError.UnmetPrecondition) {
+                string errReply = result.ErrorReason switch {
+                    RequireBotModeratorAttribute.Error => RequireBotModeratorAttribute.Reply,
+                    EnforceBlockingAttribute.FailBlocked => EnforceBlockingAttribute.ReplyBlocked,
+                    EnforceBlockingAttribute.FailModerated => EnforceBlockingAttribute.ReplyModerated,
+                    RequireGuildContextAttribute.Error => RequireGuildContextAttribute.Reply,
+                    _ => result.ErrorReason
+                };
+                await context.Interaction.RespondAsync(errReply, ephemeral: true).ConfigureAwait(false);
             } else {
                 // Generic error response
+                // TODO when implementing proper application error logging, see here
                 var ia = context.Interaction;
                 if (ia.HasResponded) await ia.ModifyOriginalResponseAsync(p => p.Content = InternalError).ConfigureAwait(false);
                 else await ia.RespondAsync(InternalError).ConfigureAwait(false);
-                // TODO when implementing proper error logging, see here
             }
         }