Allow "voice mode" to be set as default on room creation

Also, hide it behind a flag in config (experimental_voice_mode)

src/plugins/utils.js

@@ -3,6 +3,8 @@ import * as ContentHelpers from "matrix-js-sdk/lib/content-helpers";
 import dataUriToBuffer from "data-uri-to-buffer";
 import ImageResize from "image-resize";
 
+export const ROOM_TYPE_VOICE_MODE = "im.keanu.room_type_voice";
+
 const sizeOf = require("image-size");
 
 var dayjs = require('dayjs');
@@ -424,6 +426,36 @@ class Util {
         });
     }
 
+    /**
+     * Return 'true' if we should use voice mode for the given room.
+     * 
+     * The default value is given by the room itself. If the "type" of the
+     * room is set to 'im.keanu.room_type_voice' then we default to voice mode,
+     * else not. The user can then override this default by flipping the "voice mode"
+     * swicth on room settings (it will be persisted as a user specific tag on the room) 
+     */
+    useVoiceMode(roomOrNull) {
+        if (roomOrNull) {
+            const room = roomOrNull;
+
+            // Have we changed our local view mode of this room?
+            const tags = room.tags;
+            if (tags && tags["ui_options"]) {
+              return tags["ui_options"]["voice_mode"] === 1;
+            }
+  
+            // Was the room created with a voice mode type?
+            const createEvent = room.currentState.getStateEvents(
+              "m.room.create",
+              ""
+            );
+            if (createEvent) {
+                return createEvent.getContent().type === ROOM_TYPE_VOICE_MODE;
+            }
+        }
+        return false;
+    }
+
     /** Generate a random user name */
     randomUser(prefix) {
         var pfx = prefix ? prefix.replace(/[^0-9a-zA-Z\-_]/gi, '') : null;