Cleaned up permission checks, added Permissions.Has(enum) methods

src/Discord.Net.Commands/Attributes/Preconditions/RequireContextAttribute.cs

@@ -1,6 +1,4 @@
 using System;
-using System.Collections.Generic;
-using System.Linq;
 using System.Threading.Tasks;
 
 namespace Discord.Commands
@@ -8,35 +6,36 @@ namespace Discord.Commands
     [Flags]
     public enum ContextType
     {
-        Guild = 1, // 01
-        DM = 2 // 10
+        Guild = 0x01,
+        DM = 0x02,
+        Group = 0x04
     }
 
-
     [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
     public class RequireContextAttribute : PreconditionAttribute
     {
-        public ContextType Context { get; set; }
+        public ContextType Contexts { get; }
 
-        public RequireContextAttribute(ContextType context)
+        public RequireContextAttribute(ContextType contexts)
         {
-            Context = context;
+            Contexts = contexts;
         }
 
         public override Task<PreconditionResult> CheckPermissions(IMessage context, Command executingCommand, object moduleInstance)
         {
-            var validContext = false;
-
-            if (Context.HasFlag(ContextType.Guild))
-                validContext = validContext || context.Channel is IGuildChannel;
+            bool isValid = false;
 
-            if (Context.HasFlag(ContextType.DM))
-                validContext = validContext || context.Channel is IDMChannel;
+            if ((Contexts & ContextType.Guild) != 0)
+                isValid = isValid || context.Channel is IGuildChannel;
+            if ((Contexts & ContextType.DM) != 0)
+                isValid = isValid || context.Channel is IDMChannel;
+            if ((Contexts & ContextType.Group) != 0)
+                isValid = isValid || context.Channel is IGroupChannel;
 
-            if (validContext)
+            if (isValid)
                 return Task.FromResult(PreconditionResult.FromSuccess());
             else
-                return Task.FromResult(PreconditionResult.FromError($"Invalid context for command; accepted contexts: {Context}"));
+                return Task.FromResult(PreconditionResult.FromError($"Invalid context for command; accepted contexts: {Contexts}"));
         }
     }
 }

src/Discord.Net.Commands/Attributes/Preconditions/RequirePermission.cs

@@ -1,6 +1,4 @@
 using System;
-using System.Collections.Generic;
-using System.Linq;
 using System.Threading.Tasks;
 
 namespace Discord.Commands.Attributes.Preconditions
@@ -8,42 +6,44 @@ namespace Discord.Commands.Attributes.Preconditions
     [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true, Inherited = true)]
     public class RequirePermission : PreconditionAttribute
     {
-        public GuildPermission? GuildPermission { get; set; }
-        public ChannelPermission? ChannelPermission { get; set; }
+        public GuildPermission? GuildPermission { get; }
+        public ChannelPermission? ChannelPermission { get; }
 
         public RequirePermission(GuildPermission permission)
         {
             GuildPermission = permission;
             ChannelPermission = null;
         }
-
         public RequirePermission(ChannelPermission permission)
         {
             ChannelPermission = permission;
             GuildPermission = null;
         }
-
+        
         public override Task<PreconditionResult> CheckPermissions(IMessage context, Command executingCommand, object moduleInstance)
         {
-            if (!(context.Channel is IGuildChannel))
-                return Task.FromResult(PreconditionResult.FromError("Command must be used in a guild channel"));
-
-            var author = context.Author as IGuildUser;
+            var guildUser = context.Author as IGuildUser;
 
             if (GuildPermission.HasValue)
             {
-                var guildPerms = author.GuildPermissions.ToList();
-                if (!guildPerms.Contains(GuildPermission.Value))
-                    return Task.FromResult(PreconditionResult.FromError($"User is missing guild permission {GuildPermission.Value}"));
+                if (guildUser == null)
+                    return Task.FromResult(PreconditionResult.FromError("Command must be used in a guild channel"));                
+                if (!guildUser.GuildPermissions.Has(GuildPermission.Value))
+                    return Task.FromResult(PreconditionResult.FromError($"Command requires guild permission {GuildPermission.Value}"));
             }
 
             if (ChannelPermission.HasValue)
             {
-                var channel = context.Channel as IGuildChannel;
-                var channelPerms = author.GetPermissions(channel).ToList();
+                var guildChannel = context.Channel as IGuildChannel;
+
+                ChannelPermissions perms;
+                if (guildChannel != null)
+                    perms = guildUser.GetPermissions(guildChannel);
+                else
+                    perms = ChannelPermissions.All(guildChannel);
 
-                if (!channelPerms.Contains(ChannelPermission.Value))
-                    return Task.FromResult(PreconditionResult.FromError($"User is missing channel permission {ChannelPermission.Value}"));
+                if (!perms.Has(ChannelPermission.Value))
+                    return Task.FromResult(PreconditionResult.FromError($"Command requires channel permission {ChannelPermission.Value}"));
             }
 
             return Task.FromResult(PreconditionResult.FromSuccess());

src/Discord.Net/Entities/Permissions/ChannelPermissions.cs

@@ -8,9 +8,10 @@ namespace Discord
     public struct ChannelPermissions
     {
         //TODO: C#7 Candidate for binary literals
-        private static ChannelPermissions _allDM { get; } = new ChannelPermissions(Convert.ToUInt64("00010000000000111111110000011001", 2));
         private static ChannelPermissions _allText { get; } = new ChannelPermissions(Convert.ToUInt64("00000000000000011100110000000000", 2));
         private static ChannelPermissions _allVoice { get; } = new ChannelPermissions(Convert.ToUInt64("00010011111100000000000000011001", 2));
+        private static ChannelPermissions _allDM { get; } = new ChannelPermissions(Convert.ToUInt64("00010000000000111111110000011001", 2));
+        private static ChannelPermissions _allGroup { get; } = new ChannelPermissions(Convert.ToUInt64("00010000000000111111110000011001", 2));
 
         /// <summary> Gets a blank ChannelPermissions that grants no permissions. </summary>
         public static ChannelPermissions None { get; } = new ChannelPermissions();
@@ -21,6 +22,7 @@ namespace Discord
             if (channel is ITextChannel) return _allText;
             if (channel is IVoiceChannel) return _allVoice;
             if (channel is IDMChannel) return _allDM;
+            if (channel is IGroupChannel) return _allGroup;
 
             throw new ArgumentException("Unknown channel type", nameof(channel));
         }
@@ -118,6 +120,8 @@ namespace Discord
                 embedLinks, attachFiles, readMessageHistory, mentionEveryone, connect, speak, muteMembers, deafenMembers,
                 moveMembers, useVoiceActivation, managePermissions);
 
+        public bool Has(ChannelPermission permission) => Permissions.GetValue(RawValue, permission);
+
         public List<ChannelPermission> ToList()
         {
             var perms = new List<ChannelPermission>();

src/Discord.Net/Entities/Permissions/GuildPermissions.cs

@@ -129,7 +129,9 @@ namespace Discord
             => new GuildPermissions(RawValue, createInstantInvite, manageRoles, kickMembers, banMembers, manageChannels, manageGuild, readMessages,
                   sendMessages, sendTTSMessages, manageMessages, embedLinks, attachFiles, mentionEveryone, connect, speak, muteMembers, deafenMembers,
                   moveMembers, useVoiceActivation, changeNickname, manageNicknames, manageRoles);
-        
+
+        public bool Has(GuildPermission permission) => Permissions.GetValue(RawValue, permission);
+
         public List<GuildPermission> ToList()
         {
             var perms = new List<GuildPermission>();