Add command prefix configuration

PluralKit.Bot/BotConfig.cs

@@ -2,7 +2,14 @@ namespace PluralKit.Bot
 {
     public class BotConfig
     {
+        public static readonly string[] DefaultPrefixes = {"pk;", "pk!"};
+
         public string Token { get; set; }
         public ulong? ClientId { get; set; }
+        
+        // ASP.NET configuration merges arrays with defaults, so we leave this field nullable
+        // and fall back to the separate default array at the use site :)
+        // This does bind [] as null (therefore default) instead of an empty array, but I can live w/ that. 
+        public string[] Prefixes { get; set; }
     }
 }

PluralKit.Bot/Handlers/MessageCreated.cs

@@ -23,11 +23,11 @@ namespace PluralKit.Bot
         private readonly ProxyService _proxy;
         private readonly ILifetimeScope _services;
         private readonly IDatabase _db;
-        private readonly IDataStore _data;
+        private readonly BotConfig _config;
 
         public MessageCreated(LastMessageCacheService lastMessageCache, LoggerCleanService loggerClean,
                               IMetrics metrics, ProxyService proxy, DiscordShardedClient client,
-                              CommandTree tree, ILifetimeScope services, IDatabase db, IDataStore data)
+                              CommandTree tree, ILifetimeScope services, IDatabase db, BotConfig config)
         {
             _lastMessageCache = lastMessageCache;
             _loggerClean = loggerClean;
@@ -37,7 +37,7 @@ namespace PluralKit.Bot
             _tree = tree;
             _services = services;
             _db = db;
-            _data = data;
+            _config = config;
         }
 
         public DiscordChannel ErrorChannelFor(MessageCreateEventArgs evt) => evt.Channel;
@@ -87,26 +87,19 @@ namespace PluralKit.Bot
             var content = evt.Message.Content;
             if (content == null) return false;
 
-            var argPos = -1;
+            // Check for command prefix
-            // Check if message starts with the command prefix
+            if (!HasCommandPrefix(content, out var cmdStart))
-            if (content.StartsWith("pk;", StringComparison.InvariantCultureIgnoreCase)) argPos = 3;
+                return false;
-            else if (content.StartsWith("pk!", StringComparison.InvariantCultureIgnoreCase)) argPos = 3;
-            else if (DiscordUtils.HasMentionPrefix(content, ref argPos, out var id)) // Set argPos to the proper value
-                if (id != _client.CurrentUser.Id) // But undo it if it's someone else's ping
-                    argPos = -1;
 
-            // If we didn't find a prefix, give up handling commands
+            // Trim leading whitespace from command without actually modifying the string
-            if (argPos == -1) return false;
-
-            // Trim leading whitespace from command without actually modifying the wring
             // This just moves the argPos pointer by however much whitespace is at the start of the post-argPos string
-            var trimStartLengthDiff = content.Substring(argPos).Length - content.Substring(argPos).TrimStart().Length;
+            var trimStartLengthDiff = content.Substring(cmdStart).Length - content.Substring(cmdStart).TrimStart().Length;
-            argPos += trimStartLengthDiff;
+            cmdStart += trimStartLengthDiff;
 
             try
             {
                 var system = ctx.SystemId != null ? await _db.Execute(c => c.QuerySystem(ctx.SystemId.Value)) : null;
-                await _tree.ExecuteCommand(new Context(_services, evt.Client, evt.Message, argPos, system, ctx));
+                await _tree.ExecuteCommand(new Context(_services, evt.Client, evt.Message, cmdStart, system, ctx));
             }
             catch (PKError)
             {
@@ -117,6 +110,26 @@ namespace PluralKit.Bot
             return true;
         }
 
+        private bool HasCommandPrefix(string message, out int argPos)
+        {
+            // First, try prefixes defined in the config
+            var prefixes = _config.Prefixes ?? BotConfig.DefaultPrefixes;
+            foreach (var prefix in prefixes)
+            {
+                if (!message.StartsWith(prefix, StringComparison.InvariantCultureIgnoreCase)) continue;
+                
+                argPos = prefix.Length;
+                return true;
+            }
+            
+            // Then, check mention prefix (must be the bot user, ofc)
+            argPos = -1;
+            if (DiscordUtils.HasMentionPrefix(message, ref argPos, out var id))
+                return id == _client.CurrentUser.Id;
+
+            return false;
+        }
+
         private async ValueTask<bool> TryHandleProxy(MessageCreateEventArgs evt, MessageContext ctx)
         {
             try

README.md

@@ -17,6 +17,7 @@ The configuration file needs to be placed in the bot's working directory (usuall
 The configuration file is in JSON format (albeit with a `.conf` extension). The following keys are available (using `.` to indicate a nested object level), bolded key names are required:
 * **`PluralKit.Bot.Token`**: the Discord bot token to connect with
 * **`PluralKit.Database`**: the URI of the database to connect to (in [ADO.NET Npgsql format](https://www.connectionstrings.com/npgsql/))
+* `PluralKit.Bot.Prefixes`: an array of command prefixes to use (default `["pk;", "pk!"]`).
 * `PluralKit.Bot.ClientId` *(optional)*: the ID of the bot's user account, used when generating invite links through `pk;invite`. It's automatically determined if not present, but overriding it may be useful for private instances that still want a public invite link.
 * `PluralKit.SentryUrl` *(optional)*: the [Sentry](https://sentry.io/welcome/) client key/DSN to report runtime errors to. If absent, disables Sentry integration.
 * `PluralKit.InfluxUrl` *(optional)*: the URL to an [InfluxDB](https://www.influxdata.com/products/influxdb-overview/) server to report aggregate statistics to. An example of these stats can be seen on [the public stats page](https://stats.pluralkit.me).