Added support for custom errors from permission checkers

src/Discord.Net.Commands/Command.cs

@@ -95,13 +95,14 @@ namespace Discord.Commands
 			_checks = checks;
 		}
 
-		internal bool CanRun(User user, Channel channel)
+		internal bool CanRun(User user, Channel channel, out string error)
 		{
 			for (int i = 0; i < _checks.Length; i++)
 			{
-				if (!_checks[i].CanRun(this, user, channel))
+				if (!_checks[i].CanRun(this, user, channel, out error))
                     return false;
 			}
+			error = null;
 			return true;
 		}
 

src/Discord.Net.Commands/CommandMap.cs

@@ -106,25 +106,26 @@ namespace Discord.Commands
 				_commands.Add(command);
 		}
 
-		public bool CanRun(User user, Channel channel)
+		public bool CanRun(User user, Channel channel, out string error)
 		{
 			if (_commands.Count > 0)
 			{
 				foreach (var cmd in _commands)
 				{
-					if (cmd.CanRun(user, channel))
-						return true;
+					if (!cmd.CanRun(user, channel, out error))
+						return false;
 				}
 			}
 			if (_items.Count > 0)
 			{
 				foreach (var item in _items)
 				{
-					if (item.Value.CanRun(user, channel))
-						return true;
+					if (!item.Value.CanRun(user, channel, out error))
+						return false;
 				}
 			}
-			return false;
+			error = null;
+			return true;
 		}
 	}
 }

src/Discord.Net.Commands/CommandService.cs

@@ -9,7 +9,9 @@ namespace Discord.Commands
 	/// <summary> A Discord.Net client with extensions for handling common bot operations like text commands. </summary>
 	public partial class CommandService : IService
     {
-		private readonly CommandServiceConfig _config;
+		private const string DefaultPermissionError = "You do not have permission to access this command.";
+
+        private readonly CommandServiceConfig _config;
 		private readonly CommandGroupBuilder _root;
 		private DiscordClient _client;
 
@@ -119,9 +121,10 @@ After:
 						var eventArgs = new CommandEventArgs(e.Message, command, args);
 
 						// Check permissions
-						if (!command.CanRun(eventArgs.User, eventArgs.Channel))
+						string errorText;
+						if (!command.CanRun(eventArgs.User, eventArgs.Channel, out errorText))
 						{
-							RaiseCommandError(CommandErrorType.BadPermissions, eventArgs);
+							RaiseCommandError(CommandErrorType.BadPermissions, eventArgs, new Exception(errorText ?? DefaultPermissionError));
 							return;
 						}
 
@@ -162,7 +165,8 @@ After:
 				bool isFirstItem = true;
 				foreach (var group in category.Value.SubGroups)
 				{
-					if (!group.IsHidden && group.CanRun(user, channel))
+					string error;
+					if (!group.IsHidden && group.CanRun(user, channel, out error))
 					{
 						if (isFirstItem)
 						{
@@ -221,15 +225,21 @@ After:
 
 			IEnumerable<Command> cmds = map.Commands;
 			bool isFirstCmd = true;
+			string error;
 			if (cmds != null)
 			{
 				foreach (var cmd in cmds)
 				{
-					if (isFirstCmd)
-						isFirstCmd = false;
-					/*else
-						output.AppendLine();*/
-					ShowCommandHelpInternal(cmd, user, channel, output);
+					if (!cmd.CanRun(user, channel, out error)) { }
+						//output.AppendLine(error ?? DefaultPermissionError);
+					else
+					{
+						if (isFirstCmd)
+							isFirstCmd = false;
+						else
+							output.AppendLine();
+						ShowCommandHelpInternal(cmd, user, channel, output);
+					}
 				}
 			}
 			else
@@ -240,7 +250,7 @@ After:
 			}
 
 			bool isFirstSubCmd = true;
-			foreach (var subCmd in map.SubGroups.Where(x => x.CanRun(user, channel) && !x.IsHidden))
+			foreach (var subCmd in map.SubGroups.Where(x => x.CanRun(user, channel, out error) && !x.IsHidden))
 			{
 				if (isFirstSubCmd)
 				{
@@ -259,7 +269,7 @@ After:
 			if (isFirstCmd && isFirstSubCmd) //Had no commands and no subcommands
 			{
 				output.Clear();
-				output.AppendLine("You do not have permission to access this command.");
+				output.AppendLine("There are no commands you have permission to run.");
 			}
 
 			return _client.SendMessage(replyChannel ?? channel, output.ToString());
@@ -267,8 +277,9 @@ After:
 		public Task ShowCommandHelp(Command command, User user, Channel channel, Channel replyChannel = null)
 		{
 			StringBuilder output = new StringBuilder();
-			if (!command.CanRun(user, channel))
-				output.AppendLine("You do not have permission to access this command.");
+			string error;
+			if (!command.CanRun(user, channel, out error))
+				output.AppendLine(error ?? DefaultPermissionError);
 			else
 				ShowCommandHelpInternal(command, user, channel, output);
             return _client.SendMessage(replyChannel ?? channel, output.ToString());

src/Discord.Net.Commands/Permissions/IPermissionChecker.cs

@@ -2,6 +2,6 @@
 {
     public interface IPermissionChecker
     {
-		bool CanRun(Command command, User user, Channel channel);
+		bool CanRun(Command command, User user, Channel channel, out string error);
     }
 }

src/Discord.Net.Commands/Permissions/Levels/PermissionLevelChecker.cs

@@ -14,8 +14,9 @@
 			_minPermissions = minPermissions;
         }
 
-		public bool CanRun(Command command, User user, Channel channel)
+		public bool CanRun(Command command, User user, Channel channel, out string error)
 		{
+			error = null; //Use default error text.
 			int permissions = _service.GetPermissionLevel(user, channel);
 			return permissions >= _minPermissions;
 		}

src/Discord.Net.Commands/Permissions/Userlist/BlacklistChecker.cs

@@ -9,8 +9,9 @@
 			_service = client.GetService<BlacklistService>(true);
 		}
 
-		public bool CanRun(Command command, User user, Channel channel)
+		public bool CanRun(Command command, User user, Channel channel, out string error)
 		{
+			error = null; //Use default error text.
 			return _service.CanRun(user);
 		}
 	}

src/Discord.Net.Commands/Permissions/Userlist/WhitelistChecker.cs

@@ -9,8 +9,9 @@
 			_service = client.GetService<WhitelistService>(true);
 		}
 
-		public bool CanRun(Command command, User user, Channel channel)
+		public bool CanRun(Command command, User user, Channel channel, out string error)
 		{
+			error = null; //Use default error text.
 			return _service.CanRun(user);
 		}
 	}

src/Discord.Net.Modules/ModuleChecker.cs

@@ -14,9 +14,18 @@ namespace Discord.Modules
 			_filterType = manager.FilterType;
         }
 
-		public bool CanRun(Command command, User user, Channel channel)
+		public bool CanRun(Command command, User user, Channel channel, out string error)
 		{
-			return _filterType == FilterType.Unrestricted || _filterType == FilterType.AllowPrivate || _manager.HasChannel(channel);
+			if (_filterType == FilterType.Unrestricted || _filterType == FilterType.AllowPrivate || _manager.HasChannel(channel))
+			{
+				error = null;
+				return true;
+			}
+			else
+			{
+				error = "This module is currently disabled.";
+				return false;
+			}
 		}
 	}
 }