Add 'ModeratorRole' guild setting (#290)

Octobot has various moderation commands such as /ban, /mute, /kick.
These commands add multiple features to Discord's built-in functions
(such as durations and logging). Some admins may want to force their
users to use Octobot's commands instead of Discord UI functions.
However, due to the current design, they can't take away the permissions
as that remove access to the respective command.

This PR adds the `ModeratorRole` option which allows anyone who has
`ManageMessages` permission and the role to perform any moderator
action.

If the role is not set, the Discord permissions are checked instead. If
the user doesn't have the role, but has the permission, they can still
run the command.

---------

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

locale/Messages.resx

@@ -231,8 +231,11 @@
   <data name="UserCannotKickMembers" xml:space="preserve">
     <value>You cannot kick members from this guild!</value>
   </data>
-  <data name="UserCannotModerateMembers" xml:space="preserve">
+    <data name="UserCannotMuteMembers" xml:space="preserve">
-    <value>You cannot moderate members in this guild!</value>
+    <value>You cannot mute members in this guild!</value>
+  </data>
+    <data name="UserCannotUnmuteMembers" xml:space="preserve">
+    <value>You cannot unmute members in this guild!</value>
   </data>
   <data name="UserCannotManageGuild" xml:space="preserve">
     <value>You cannot manage this guild!</value>
@@ -675,4 +678,7 @@
   <data name="ButtonOpenWiki" xml:space="preserve">
       <value>Open Octobot's Wiki</value>
   </data>
+    <data name="SettingsModeratorRole" xml:space="preserve">
+      <value>Moderator role</value>
+  </data>
 </root>

locale/Messages.ru.resx

@@ -228,8 +228,11 @@
   <data name="UserCannotKickMembers" xml:space="preserve">
     <value>Ты не можешь выгонять участников с этого сервера!</value>
   </data>
-  <data name="UserCannotModerateMembers" xml:space="preserve">
+    <data name="UserCannotMuteMembers" xml:space="preserve">
-    <value>Ты не можешь модерировать участников этого сервера!</value>
+    <value>Ты не можешь глушить участников этого сервера!</value>
+  </data>
+    <data name="UserCannotUnmuteMembers" xml:space="preserve">
+    <value>Ты не можешь разглушать участников этого сервера!</value>
   </data>
   <data name="UserCannotManageGuild" xml:space="preserve">
     <value>Ты не можешь настраивать этот сервер!</value>
@@ -675,4 +678,7 @@
   <data name="ButtonOpenWiki" xml:space="preserve">
       <value>Открыть Octobot's Wiki</value>
   </data>
+    <data name="SettingsModeratorRole" xml:space="preserve">
+      <value>Роль модератора</value>
+  </data>
 </root>

locale/Messages.tt-ru.resx

@@ -231,8 +231,11 @@
   <data name="UserCannotKickMembers" xml:space="preserve">
     <value>кик шизиков нельзя</value>
   </data>
-  <data name="UserCannotModerateMembers" xml:space="preserve">
+    <data name="UserCannotMuteMembers" xml:space="preserve">
-    <value>тебе нельзя управлять шизоидами</value>
+    <value>тебе нельзя мутить шизоидов</value>
+  </data>
+    <data name="UserCannotUnmuteMembers" xml:space="preserve">
+    <value>тебе нельзя раззамучивать шизоидов</value>
   </data>
   <data name="UserCannotManageGuild" xml:space="preserve">
     <value>тебе нельзя редактировать дурку</value>
@@ -675,4 +678,7 @@
   <data name="ButtonOpenWiki" xml:space="preserve">
       <value>вики Octobot (жмак)</value>
   </data>
+    <data name="SettingsModeratorRole" xml:space="preserve">
+      <value>звание админа</value>
+  </data>
 </root>

src/Commands/BanCommandGroup.cs

@@ -28,6 +28,7 @@ namespace Octobot.Commands;
 [UsedImplicitly]
 public class BanCommandGroup : CommandGroup
 {
+    private readonly AccessControlService _access;
     private readonly IDiscordRestChannelAPI _channelApi;
     private readonly ICommandContext _context;
     private readonly IFeedbackService _feedback;
@@ -36,16 +37,16 @@ public class BanCommandGroup : CommandGroup
     private readonly IDiscordRestUserAPI _userApi;
     private readonly Utility _utility;
 
-    public BanCommandGroup(
+    public BanCommandGroup(AccessControlService access, IDiscordRestChannelAPI channelApi, ICommandContext context,
-        ICommandContext context, IDiscordRestChannelAPI channelApi, GuildDataService guildData,
+        IFeedbackService feedback, IDiscordRestGuildAPI guildApi, GuildDataService guildData,
-        IFeedbackService feedback, IDiscordRestGuildAPI guildApi, IDiscordRestUserAPI userApi,
+        IDiscordRestUserAPI userApi, Utility utility)
-        Utility utility)
     {
-        _context = context;
+        _access = access;
         _channelApi = channelApi;
-        _guildData = guildData;
+        _context = context;
         _feedback = feedback;
         _guildApi = guildApi;
+        _guildData = guildData;
         _userApi = userApi;
         _utility = utility;
     }
@@ -65,10 +66,10 @@ public class BanCommandGroup : CommandGroup
     /// </returns>
     /// <seealso cref="ExecuteUnban" />
     [Command("ban", "бан")]
-    [DiscordDefaultMemberPermissions(DiscordPermission.BanMembers)]
+    [DiscordDefaultMemberPermissions(DiscordPermission.ManageMessages)]
     [DiscordDefaultDMPermission(false)]
     [RequireContext(ChannelContext.Guild)]
-    [RequireDiscordPermission(DiscordPermission.BanMembers)]
+    [RequireDiscordPermission(DiscordPermission.ManageMessages)]
     [RequireBotDiscordPermissions(DiscordPermission.BanMembers)]
     [Description("Ban user")]
     [UsedImplicitly]
@@ -128,7 +129,8 @@ public class BanCommandGroup : CommandGroup
     }
 
     private async Task<Result> BanUserAsync(
-        IUser executor, IUser target, string reason, TimeSpan? duration, IGuild guild, GuildData data, Snowflake channelId,
+        IUser executor, IUser target, string reason, TimeSpan? duration, IGuild guild, GuildData data,
+        Snowflake channelId,
         IUser bot, CancellationToken ct = default)
     {
         var existingBanResult = await _guildApi.GetGuildBanAsync(guild.ID, target.ID, ct);
@@ -141,7 +143,7 @@ public class BanCommandGroup : CommandGroup
         }
 
         var interactionResult
-            = await _utility.CheckInteractionsAsync(guild.ID, executor.ID, target.ID, "Ban", ct);
+            = await _access.CheckInteractionsAsync(guild.ID, executor.ID, target.ID, "Ban", ct);
         if (!interactionResult.IsSuccess)
         {
             return ResultExtensions.FromError(interactionResult);
@@ -155,7 +157,8 @@ public class BanCommandGroup : CommandGroup
             return await _feedback.SendContextualEmbedResultAsync(errorEmbed, ct: ct);
         }
 
-        var builder = new StringBuilder().AppendBulletPointLine(string.Format(Messages.DescriptionActionReason, reason));
+        var builder =
+            new StringBuilder().AppendBulletPointLine(string.Format(Messages.DescriptionActionReason, reason));
         if (duration is not null)
         {
             builder.AppendBulletPoint(
@@ -221,10 +224,10 @@ public class BanCommandGroup : CommandGroup
     /// <seealso cref="ExecuteBanAsync" />
     /// <seealso cref="MemberUpdateService.TickMemberDataAsync" />
     [Command("unban")]
-    [DiscordDefaultMemberPermissions(DiscordPermission.BanMembers)]
+    [DiscordDefaultMemberPermissions(DiscordPermission.ManageMessages)]
     [DiscordDefaultDMPermission(false)]
     [RequireContext(ChannelContext.Guild)]
-    [RequireDiscordPermission(DiscordPermission.BanMembers)]
+    [RequireDiscordPermission(DiscordPermission.ManageMessages)]
     [RequireBotDiscordPermissions(DiscordPermission.BanMembers)]
     [Description("Unban user")]
     [UsedImplicitly]
@@ -286,7 +289,8 @@ public class BanCommandGroup : CommandGroup
             .WithColour(ColorsList.Green).Build();
 
         var title = string.Format(Messages.UserUnbanned, target.GetTag());
-        var description = new StringBuilder().AppendBulletPoint(string.Format(Messages.DescriptionActionReason, reason));
+        var description =
+            new StringBuilder().AppendBulletPoint(string.Format(Messages.DescriptionActionReason, reason));
 
         _utility.LogAction(
             data.Settings, channelId, executor, title, description.ToString(), target, ColorsList.Green, ct: ct);

src/Commands/KickCommandGroup.cs

@@ -24,6 +24,7 @@ namespace Octobot.Commands;
 [UsedImplicitly]
 public class KickCommandGroup : CommandGroup
 {
+    private readonly AccessControlService _access;
     private readonly IDiscordRestChannelAPI _channelApi;
     private readonly ICommandContext _context;
     private readonly IFeedbackService _feedback;
@@ -32,16 +33,16 @@ public class KickCommandGroup : CommandGroup
     private readonly IDiscordRestUserAPI _userApi;
     private readonly Utility _utility;
 
-    public KickCommandGroup(
+    public KickCommandGroup(AccessControlService access, IDiscordRestChannelAPI channelApi, ICommandContext context,
-        ICommandContext context, IDiscordRestChannelAPI channelApi, GuildDataService guildData,
+        IFeedbackService feedback, IDiscordRestGuildAPI guildApi, GuildDataService guildData,
-        IFeedbackService feedback, IDiscordRestGuildAPI guildApi, IDiscordRestUserAPI userApi,
+        IDiscordRestUserAPI userApi, Utility utility)
-        Utility utility)
     {
-        _context = context;
+        _access = access;
         _channelApi = channelApi;
-        _guildData = guildData;
+        _context = context;
         _feedback = feedback;
         _guildApi = guildApi;
+        _guildData = guildData;
         _userApi = userApi;
         _utility = utility;
     }
@@ -59,10 +60,10 @@ public class KickCommandGroup : CommandGroup
     ///     was kicked and vice-versa.
     /// </returns>
     [Command("kick", "кик")]
-    [DiscordDefaultMemberPermissions(DiscordPermission.KickMembers)]
+    [DiscordDefaultMemberPermissions(DiscordPermission.ManageMessages)]
     [DiscordDefaultDMPermission(false)]
     [RequireContext(ChannelContext.Guild)]
-    [RequireDiscordPermission(DiscordPermission.KickMembers)]
+    [RequireDiscordPermission(DiscordPermission.ManageMessages)]
     [RequireBotDiscordPermissions(DiscordPermission.KickMembers)]
     [Description("Kick member")]
     [UsedImplicitly]
@@ -115,7 +116,7 @@ public class KickCommandGroup : CommandGroup
         CancellationToken ct = default)
     {
         var interactionResult
-            = await _utility.CheckInteractionsAsync(guild.ID, executor.ID, target.ID, "Kick", ct);
+            = await _access.CheckInteractionsAsync(guild.ID, executor.ID, target.ID, "Kick", ct);
         if (!interactionResult.IsSuccess)
         {
             return ResultExtensions.FromError(interactionResult);
@@ -134,7 +135,8 @@ public class KickCommandGroup : CommandGroup
         {
             var dmEmbed = new EmbedBuilder().WithGuildTitle(guild)
                 .WithTitle(Messages.YouWereKicked)
-                .WithDescription(MarkdownExtensions.BulletPoint(string.Format(Messages.DescriptionActionReason, reason)))
+                .WithDescription(
+                    MarkdownExtensions.BulletPoint(string.Format(Messages.DescriptionActionReason, reason)))
                 .WithActionFooter(executor)
                 .WithCurrentTimestamp()
                 .WithColour(ColorsList.Red)

src/Commands/MuteCommandGroup.cs

@@ -28,6 +28,7 @@ namespace Octobot.Commands;
 [UsedImplicitly]
 public class MuteCommandGroup : CommandGroup
 {
+    private readonly AccessControlService _access;
     private readonly ICommandContext _context;
     private readonly IFeedbackService _feedback;
     private readonly IDiscordRestGuildAPI _guildApi;
@@ -35,14 +36,14 @@ public class MuteCommandGroup : CommandGroup
     private readonly IDiscordRestUserAPI _userApi;
     private readonly Utility _utility;
 
-    public MuteCommandGroup(
+    public MuteCommandGroup(AccessControlService access, ICommandContext context, IFeedbackService feedback,
-        ICommandContext context, GuildDataService guildData, IFeedbackService feedback,
+        IDiscordRestGuildAPI guildApi, GuildDataService guildData, IDiscordRestUserAPI userApi, Utility utility)
-        IDiscordRestGuildAPI guildApi, IDiscordRestUserAPI userApi, Utility utility)
     {
+        _access = access;
         _context = context;
-        _guildData = guildData;
         _feedback = feedback;
         _guildApi = guildApi;
+        _guildData = guildData;
         _userApi = userApi;
         _utility = utility;
     }
@@ -62,10 +63,10 @@ public class MuteCommandGroup : CommandGroup
     /// </returns>
     /// <seealso cref="ExecuteUnmute" />
     [Command("mute", "мут")]
-    [DiscordDefaultMemberPermissions(DiscordPermission.ModerateMembers)]
+    [DiscordDefaultMemberPermissions(DiscordPermission.ManageMessages)]
     [DiscordDefaultDMPermission(false)]
     [RequireContext(ChannelContext.Guild)]
-    [RequireDiscordPermission(DiscordPermission.ModerateMembers)]
+    [RequireDiscordPermission(DiscordPermission.ManageMessages)]
     [RequireBotDiscordPermissions(DiscordPermission.ModerateMembers)]
     [Description("Mute member")]
     [UsedImplicitly]
@@ -127,7 +128,7 @@ public class MuteCommandGroup : CommandGroup
         Snowflake channelId, IUser bot, CancellationToken ct = default)
     {
         var interactionResult
-            = await _utility.CheckInteractionsAsync(
+            = await _access.CheckInteractionsAsync(
                 guildId, executor.ID, target.ID, "Mute", ct);
         if (!interactionResult.IsSuccess)
         {
@@ -239,10 +240,10 @@ public class MuteCommandGroup : CommandGroup
     /// <seealso cref="ExecuteMute" />
     /// <seealso cref="MemberUpdateService.TickMemberDataAsync" />
     [Command("unmute", "размут")]
-    [DiscordDefaultMemberPermissions(DiscordPermission.ModerateMembers)]
+    [DiscordDefaultMemberPermissions(DiscordPermission.ManageMessages)]
     [DiscordDefaultDMPermission(false)]
     [RequireContext(ChannelContext.Guild)]
-    [RequireDiscordPermission(DiscordPermission.ModerateMembers)]
+    [RequireDiscordPermission(DiscordPermission.ManageMessages)]
     [RequireBotDiscordPermissions(DiscordPermission.ModerateMembers)]
     [Description("Unmute member")]
     [UsedImplicitly]
@@ -290,7 +291,7 @@ public class MuteCommandGroup : CommandGroup
         IUser bot, CancellationToken ct = default)
     {
         var interactionResult
-            = await _utility.CheckInteractionsAsync(
+            = await _access.CheckInteractionsAsync(
                 guildId, executor.ID, target.ID, "Unmute", ct);
         if (!interactionResult.IsSuccess)
         {

src/Commands/SettingsCommandGroup.cs

@@ -51,6 +51,7 @@ public class SettingsCommandGroup : CommandGroup
         GuildSettings.EventNotificationChannel,
         GuildSettings.DefaultRole,
         GuildSettings.MuteRole,
+        GuildSettings.ModeratorRole,
         GuildSettings.EventNotificationRole,
         GuildSettings.EventEarlyNotificationOffset
     ];

src/Data/GuildSettings.cs

@@ -76,6 +76,7 @@ public static class GuildSettings
     public static readonly SnowflakeOption EventNotificationChannel = new("EventNotificationChannel");
     public static readonly SnowflakeOption DefaultRole = new("DefaultRole");
     public static readonly SnowflakeOption MuteRole = new("MuteRole");
+    public static readonly SnowflakeOption ModeratorRole = new("ModeratorRole");
     public static readonly SnowflakeOption EventNotificationRole = new("EventNotificationRole");
 
     /// <summary>

src/Data/Options/AllOptionsEnum.cs

@@ -26,6 +26,7 @@ public enum AllOptionsEnum
     [UsedImplicitly] EventNotificationChannel,
     [UsedImplicitly] DefaultRole,
     [UsedImplicitly] MuteRole,
+    [UsedImplicitly] ModeratorRole,
     [UsedImplicitly] EventNotificationRole,
     [UsedImplicitly] EventEarlyNotificationOffset
 }

src/Octobot.cs

@@ -88,8 +88,9 @@ public sealed class Octobot
                         .AddPreparationErrorEvent<LoggingPreparationErrorEvent>()
                         .AddPostExecutionEvent<ErrorLoggingPostExecutionEvent>()
                         // Services
-                        .AddSingleton<Utility>()
+                        .AddSingleton<AccessControlService>()
                         .AddSingleton<GuildDataService>()
+                        .AddSingleton<Utility>()
                         .AddHostedService<GuildDataService>(provider => provider.GetRequiredService<GuildDataService>())
                         .AddHostedService<MemberUpdateService>()
                         .AddHostedService<ScheduledEventUpdateService>()

src/Services/AccessControlService.cs

@@ -0,0 +1,176 @@
+using Octobot.Data;
+using Octobot.Extensions;
+using Remora.Discord.API.Abstractions.Objects;
+using Remora.Discord.API.Abstractions.Rest;
+using Remora.Discord.Commands.Conditions;
+using Remora.Discord.Commands.Results;
+using Remora.Rest.Core;
+using Remora.Results;
+
+namespace Octobot.Services;
+
+public sealed class AccessControlService
+{
+    private readonly GuildDataService _data;
+    private readonly IDiscordRestGuildAPI _guildApi;
+    private readonly RequireDiscordPermissionCondition _permission;
+    private readonly IDiscordRestUserAPI _userApi;
+
+    public AccessControlService(GuildDataService data, IDiscordRestGuildAPI guildApi, IDiscordRestUserAPI userApi,
+        RequireDiscordPermissionCondition permission)
+    {
+        _data = data;
+        _guildApi = guildApi;
+        _userApi = userApi;
+        _permission = permission;
+    }
+
+    private async Task<Result<bool>> CheckPermissionAsync(GuildData data, Snowflake memberId, IGuildMember member,
+        DiscordPermission permission, CancellationToken ct = default)
+    {
+        var moderatorRole = GuildSettings.ModeratorRole.Get(data.Settings);
+        var result = await _permission.CheckAsync(new RequireDiscordPermissionAttribute([permission]), member, ct);
+
+        if (result.Error is not null and not PermissionDeniedError)
+        {
+            return Result<bool>.FromError(result);
+        }
+
+        var hasPermission = result.IsSuccess;
+        return hasPermission || (!moderatorRole.Empty() &&
+                                 data.GetOrCreateMemberData(memberId).Roles.Contains(moderatorRole.Value));
+    }
+
+    /// <summary>
+    ///     Checks whether or not a member can interact with another member
+    /// </summary>
+    /// <param name="guildId">The ID of the guild in which an operation is being performed.</param>
+    /// <param name="interacterId">The executor of the operation.</param>
+    /// <param name="targetId">The target of the operation.</param>
+    /// <param name="action">The operation.</param>
+    /// <param name="ct">The cancellation token for this operation.</param>
+    /// <returns>
+    ///     <list type="bullet">
+    ///         <item>A result which has succeeded with a null string if the member can interact with the target.</item>
+    ///         <item>
+    ///             A result which has succeeded with a non-null string containing the error message if the member cannot
+    ///             interact with the target.
+    ///         </item>
+    ///         <item>A result which has failed if an error occurred during the execution of this method.</item>
+    ///     </list>
+    /// </returns>
+    public async Task<Result<string?>> CheckInteractionsAsync(
+        Snowflake guildId, Snowflake? interacterId, Snowflake targetId, string action, CancellationToken ct = default)
+    {
+        if (interacterId == targetId)
+        {
+            return Result<string?>.FromSuccess($"UserCannot{action}Themselves".Localized());
+        }
+
+        var botResult = await _userApi.GetCurrentUserAsync(ct);
+        if (!botResult.IsDefined(out var bot))
+        {
+            return Result<string?>.FromError(botResult);
+        }
+
+        var guildResult = await _guildApi.GetGuildAsync(guildId, ct: ct);
+        if (!guildResult.IsDefined(out var guild))
+        {
+            return Result<string?>.FromError(guildResult);
+        }
+
+        var targetMemberResult = await _guildApi.GetGuildMemberAsync(guildId, targetId, ct);
+        if (!targetMemberResult.IsDefined(out var targetMember))
+        {
+            return Result<string?>.FromSuccess(null);
+        }
+
+        var currentMemberResult = await _guildApi.GetGuildMemberAsync(guildId, bot.ID, ct);
+        if (!currentMemberResult.IsDefined(out var currentMember))
+        {
+            return Result<string?>.FromError(currentMemberResult);
+        }
+
+        var rolesResult = await _guildApi.GetGuildRolesAsync(guildId, ct);
+        if (!rolesResult.IsDefined(out var roles))
+        {
+            return Result<string?>.FromError(rolesResult);
+        }
+
+        if (interacterId is null)
+        {
+            return CheckInteractions(action, guild, roles, targetMember, currentMember, currentMember);
+        }
+
+        var interacterResult = await _guildApi.GetGuildMemberAsync(guildId, interacterId.Value, ct);
+        if (!interacterResult.IsDefined(out var interacter))
+        {
+            return Result<string?>.FromError(interacterResult);
+        }
+
+        var data = await _data.GetData(guildId, ct);
+
+        var permissionResult = await CheckPermissionAsync(data, interacterId.Value, interacter,
+            action switch
+            {
+                "Ban" => DiscordPermission.BanMembers,
+                "Kick" => DiscordPermission.KickMembers,
+                "Mute" or "Unmute" => DiscordPermission.ModerateMembers,
+                _ => throw new Exception()
+            }, ct);
+        if (!permissionResult.IsDefined(out var hasPermission))
+        {
+            return Result<string?>.FromError(permissionResult);
+        }
+
+        return hasPermission
+            ? CheckInteractions(action, guild, roles, targetMember, currentMember, interacter)
+            : Result<string?>.FromSuccess($"UserCannot{action}Members".Localized());
+    }
+
+    private static Result<string?> CheckInteractions(
+        string action, IGuild guild, IReadOnlyList<IRole> roles, IGuildMember targetMember, IGuildMember currentMember,
+        IGuildMember interacter)
+    {
+        if (!targetMember.User.IsDefined(out var targetUser))
+        {
+            return new ArgumentNullError(nameof(targetMember.User));
+        }
+
+        if (!interacter.User.IsDefined(out var interacterUser))
+        {
+            return new ArgumentNullError(nameof(interacter.User));
+        }
+
+        if (currentMember.User == targetMember.User)
+        {
+            return Result<string?>.FromSuccess($"UserCannot{action}Bot".Localized());
+        }
+
+        if (targetUser.ID == guild.OwnerID)
+        {
+            return Result<string?>.FromSuccess($"UserCannot{action}Owner".Localized());
+        }
+
+        var targetRoles = roles.Where(r => targetMember.Roles.Contains(r.ID)).ToList();
+        var botRoles = roles.Where(r => currentMember.Roles.Contains(r.ID));
+
+        var targetBotRoleDiff = targetRoles.MaxOrDefault(r => r.Position) - botRoles.MaxOrDefault(r => r.Position);
+        if (targetBotRoleDiff >= 0)
+        {
+            return Result<string?>.FromSuccess($"BotCannot{action}Target".Localized());
+        }
+
+        if (interacterUser.ID == guild.OwnerID)
+        {
+            return Result<string?>.FromSuccess(null);
+        }
+
+        var interacterRoles = roles.Where(r => interacter.Roles.Contains(r.ID));
+        var targetInteracterRoleDiff
+            = targetRoles.MaxOrDefault(r => r.Position) - interacterRoles.MaxOrDefault(r => r.Position);
+        return targetInteracterRoleDiff < 0
+            ? Result<string?>.FromSuccess(null)
+            : Result<string?>.FromSuccess($"UserCannot{action}Target".Localized());
+    }
+}

src/Services/Update/MemberUpdateService.cs

@@ -26,20 +26,20 @@ public sealed partial class MemberUpdateService : BackgroundService
         "Torus", "Violet", "Vortex", "Vulture", "Wagon", "Whale", "Woodpecker", "Zebra", "Zigzag"
     ];
 
+    private readonly AccessControlService _access;
     private readonly IDiscordRestChannelAPI _channelApi;
     private readonly IDiscordRestGuildAPI _guildApi;
     private readonly GuildDataService _guildData;
     private readonly ILogger<MemberUpdateService> _logger;
-    private readonly Utility _utility;
 
-    public MemberUpdateService(IDiscordRestChannelAPI channelApi, IDiscordRestGuildAPI guildApi,
+    public MemberUpdateService(AccessControlService access, IDiscordRestChannelAPI channelApi,
-        GuildDataService guildData, ILogger<MemberUpdateService> logger, Utility utility)
+        IDiscordRestGuildAPI guildApi, GuildDataService guildData, ILogger<MemberUpdateService> logger)
     {
+        _access = access;
         _channelApi = channelApi;
         _guildApi = guildApi;
         _guildData = guildData;
         _logger = logger;
-        _utility = utility;
     }
 
     protected override async Task ExecuteAsync(CancellationToken ct)
@@ -94,7 +94,7 @@ public sealed partial class MemberUpdateService : BackgroundService
         }
 
         var interactionResult
-            = await _utility.CheckInteractionsAsync(guildId, null, id, "Update", ct);
+            = await _access.CheckInteractionsAsync(guildId, null, id, "Update", ct);
         if (!interactionResult.IsSuccess)
         {
             return ResultExtensions.FromError(interactionResult);

src/Services/Utility.cs

@@ -21,129 +21,13 @@ public sealed class Utility
     private readonly IDiscordRestChannelAPI _channelApi;
     private readonly IDiscordRestGuildScheduledEventAPI _eventApi;
     private readonly IDiscordRestGuildAPI _guildApi;
-    private readonly IDiscordRestUserAPI _userApi;
 
     public Utility(
-        IDiscordRestChannelAPI channelApi, IDiscordRestGuildScheduledEventAPI eventApi, IDiscordRestGuildAPI guildApi,
+        IDiscordRestChannelAPI channelApi, IDiscordRestGuildScheduledEventAPI eventApi, IDiscordRestGuildAPI guildApi)
-        IDiscordRestUserAPI userApi)
     {
         _channelApi = channelApi;
         _eventApi = eventApi;
         _guildApi = guildApi;
-        _userApi = userApi;
-    }
-
-    /// <summary>
-    ///     Checks whether or not a member can interact with another member
-    /// </summary>
-    /// <param name="guildId">The ID of the guild in which an operation is being performed.</param>
-    /// <param name="interacterId">The executor of the operation.</param>
-    /// <param name="targetId">The target of the operation.</param>
-    /// <param name="action">The operation.</param>
-    /// <param name="ct">The cancellation token for this operation.</param>
-    /// <returns>
-    ///     <list type="bullet">
-    ///         <item>A result which has succeeded with a null string if the member can interact with the target.</item>
-    ///         <item>
-    ///             A result which has succeeded with a non-null string containing the error message if the member cannot
-    ///             interact with the target.
-    ///         </item>
-    ///         <item>A result which has failed if an error occurred during the execution of this method.</item>
-    ///     </list>
-    /// </returns>
-    public async Task<Result<string?>> CheckInteractionsAsync(
-        Snowflake guildId, Snowflake? interacterId, Snowflake targetId, string action, CancellationToken ct = default)
-    {
-        if (interacterId == targetId)
-        {
-            return Result<string?>.FromSuccess($"UserCannot{action}Themselves".Localized());
-        }
-
-        var botResult = await _userApi.GetCurrentUserAsync(ct);
-        if (!botResult.IsDefined(out var bot))
-        {
-            return Result<string?>.FromError(botResult);
-        }
-
-        var guildResult = await _guildApi.GetGuildAsync(guildId, ct: ct);
-        if (!guildResult.IsDefined(out var guild))
-        {
-            return Result<string?>.FromError(guildResult);
-        }
-
-        var targetMemberResult = await _guildApi.GetGuildMemberAsync(guildId, targetId, ct);
-        if (!targetMemberResult.IsDefined(out var targetMember))
-        {
-            return Result<string?>.FromSuccess(null);
-        }
-
-        var currentMemberResult = await _guildApi.GetGuildMemberAsync(guildId, bot.ID, ct);
-        if (!currentMemberResult.IsDefined(out var currentMember))
-        {
-            return Result<string?>.FromError(currentMemberResult);
-        }
-
-        var rolesResult = await _guildApi.GetGuildRolesAsync(guildId, ct);
-        if (!rolesResult.IsDefined(out var roles))
-        {
-            return Result<string?>.FromError(rolesResult);
-        }
-
-        if (interacterId is null)
-        {
-            return CheckInteractions(action, guild, roles, targetMember, currentMember, currentMember);
-        }
-
-        var interacterResult = await _guildApi.GetGuildMemberAsync(guildId, interacterId.Value, ct);
-        return interacterResult.IsDefined(out var interacter)
-            ? CheckInteractions(action, guild, roles, targetMember, currentMember, interacter)
-            : Result<string?>.FromError(interacterResult);
-    }
-
-    private static Result<string?> CheckInteractions(
-        string action, IGuild guild, IReadOnlyList<IRole> roles, IGuildMember targetMember, IGuildMember currentMember,
-        IGuildMember interacter)
-    {
-        if (!targetMember.User.IsDefined(out var targetUser))
-        {
-            return new ArgumentNullError(nameof(targetMember.User));
-        }
-
-        if (!interacter.User.IsDefined(out var interacterUser))
-        {
-            return new ArgumentNullError(nameof(interacter.User));
-        }
-
-        if (currentMember.User == targetMember.User)
-        {
-            return Result<string?>.FromSuccess($"UserCannot{action}Bot".Localized());
-        }
-
-        if (targetUser.ID == guild.OwnerID)
-        {
-            return Result<string?>.FromSuccess($"UserCannot{action}Owner".Localized());
-        }
-
-        var targetRoles = roles.Where(r => targetMember.Roles.Contains(r.ID)).ToList();
-        var botRoles = roles.Where(r => currentMember.Roles.Contains(r.ID));
-
-        var targetBotRoleDiff = targetRoles.MaxOrDefault(r => r.Position) - botRoles.MaxOrDefault(r => r.Position);
-        if (targetBotRoleDiff >= 0)
-        {
-            return Result<string?>.FromSuccess($"BotCannot{action}Target".Localized());
-        }
-
-        if (interacterUser.ID == guild.OwnerID)
-        {
-            return Result<string?>.FromSuccess(null);
-        }
-
-        var interacterRoles = roles.Where(r => interacter.Roles.Contains(r.ID));
-        var targetInteracterRoleDiff
-            = targetRoles.MaxOrDefault(r => r.Position) - interacterRoles.MaxOrDefault(r => r.Position);
-        return targetInteracterRoleDiff < 0
-            ? Result<string?>.FromSuccess(null)
-            : Result<string?>.FromSuccess($"UserCannot{action}Target".Localized());
     }
 
     /// <summary>