Add options to specify custom command prefixes

Fixes https://github.com/matrix-org/mjolnir/issues/29

config/default.yaml

@@ -93,3 +93,20 @@ banListServer:
   enabled: false
   bind: "0.0.0.0"
   port: 5186
+
+# Misc options for command handling and commands
+commands:
+  # If true, Mjolnir will respond to commands like !help and !ban instead of
+  # requiring a prefix. This is useful if Mjolnir is the only bot running in
+  # your management room.
+  #
+  # Note that Mjolnir can be pinged by display name instead of having to use
+  # the !mjolnir prefix. For example, "my_moderator_bot: ban @spammer:example.org"
+  # will ban a user.
+  allowNoPrefix: false
+
+  # In addition to the bot's display name, !mjolnir, and optionally no prefix
+  # above, the bot will respond to these names. The items here can be used either
+  # as display names or prefixed with exclamation points.
+  additionalPrefixes:
+    - "mjolnir_bot"

src/Mjolnir.ts

@@ -63,12 +63,24 @@ export class Mjolnir {
 
             const content = event['content'];
             if (content['msgtype'] === "m.text" && content['body']) {
-                const prefixes = [COMMAND_PREFIX, this.localpart + ":", this.displayName + ":", await client.getUserId() + ":"];
+                const prefixes = [
+                    COMMAND_PREFIX,
+                    this.localpart + ":",
+                    this.displayName + ":",
+                    await client.getUserId() + ":",
+                    ...config.commands.additionalPrefixes.map(p => `!${p}`),
+                    ...config.commands.additionalPrefixes.map(p => `${p}:`),
+                    ...config.commands.additionalPrefixes,
+                ];
+                if (config.commands.allowNoPrefix) prefixes.push("!");
+
                 const prefixUsed = prefixes.find(p => content['body'].startsWith(p));
                 if (!prefixUsed) return;
 
                 // rewrite the event body to make the prefix uniform (in case the bot has spaces in its display name)
-                event['content']['body'] = COMMAND_PREFIX + content['body'].substring(prefixUsed.length);
+                let restOfBody = content['body'].substring(prefixUsed.length);
+                if (!restOfBody.startsWith(" ")) restOfBody = ` ${restOfBody}`;
+                event['content']['body'] = COMMAND_PREFIX + restOfBody;
                 LogService.info("Mjolnir", `Command being run by ${event['sender']}: ${event['content']['body']}`);
 
                 await client.sendReadReceipt(roomId, event['event_id']);

src/config.ts

@@ -43,6 +43,10 @@ interface IConfig {
         bind: string;
         port: number;
     };
+    commands: {
+        allowNoPrefix: boolean;
+        additionalPrefixes: string[];
+    };
 
     /**
      * Config options only set at runtime. Try to avoid using the objects