Add provisioning route for getting misc bridge info

Currently only the relay bot's username is exposed here.

mautrix_telegram/web/provisioning/__init__.py

@@ -64,6 +64,8 @@ class ProvisioningAPI(AuthAPI):
         self.app.router.add_route("POST", f"{user_prefix}/login/send_code", self.send_code)
         self.app.router.add_route("POST", f"{user_prefix}/login/send_password", self.send_password)
 
+        self.app.router.add_route("GET", f"/bridge", self.bridge_info)
+
     async def get_portal_by_mxid(self, request: web.Request) -> web.Response:
         err = self.check_authorization(request)
         if err is not None:
@@ -359,6 +361,11 @@ class ProvisioningAPI(AuthAPI):
             return err
         await user.log_out()
 
+    async def bridge_info(self, request: web.Request) -> web.Response:
+        return web.json_response({
+            "relaybot_username": self.context.bot.username,
+        }, status=200)
+
     @staticmethod
     async def error_middleware(_, handler: Callable[[web.Request], Awaitable[web.Response]]
                                ) -> Callable[[web.Request], Awaitable[web.Response]]:

mautrix_telegram/web/provisioning/spec.yaml

@@ -24,6 +24,20 @@ tags:
 - name: Bridging
 
 paths:
+  /bridge:
+    get:
+      operationId: get_bridge
+      summary: Get the bridge's information
+      tags: [Misc]
+      responses:
+        200:
+          description: The bridge information
+          schama:
+            type: object
+            properties:
+              relay_username:
+                type: string
+                description: The relay bot's username on Telegram
   /portal/{room_id}:
     get:
       operationId: get_portal