feat: allow admin to respond directly in telegram

Allow admins to respond to feedback messages by replying to the message in
Telegram, instead of the current process of having to manually POST to the
telemsg API. This should make it extremely easy to respond to future feedback.

Determine responses by parsing the message that the admin is replying to, but
this is a pretty bad implementation that couples the new handler with how the
current `/feedback` handler sends messages to admin. To fix this, we'd have to
offload the messaging to a separate service, but it isn't worth doing now.

Messages are sent by POST-ing to the telemsg API. This responsibility should
also be offloaded to a separate service, along with the POST-ing done in the
`/feedback` handler, but again it isn't worth doing.

docker-compose.yml

@@ -88,6 +88,7 @@ services:
     image: evs-telebot:latest
     environment:
       TELEGRAM_TOKEN: "${TELEGRAM_TOKEN}"
+      TELEGRAM_ADMIN_ID: "${TELEGRAM_ADMIN_ID}"
       DB_API_HOST: "db_api"
       DB_API_PORT: 8080
       TELEMSG_API_HOST: "telemsg_api"

hosts/telebot/src/bot/bot.py

@@ -1,5 +1,5 @@
 from telegram.ext import Updater
-from .handlers import commands as cmd
+from .handlers import commands as cmd, message
 from .handlers.conv import (add_subscription as add,
                             view_subscription as view,
                             feedback as feedback)
@@ -16,6 +16,7 @@ def add_handlers(self):
         self.dispatcher.add_handler(add.conv_handler)
         self.dispatcher.add_handler(view.conv_handler)
         self.dispatcher.add_handler(feedback.conv_handler)
+        self.dispatcher.add_handler(message.message_handler)
 
     def start(self):
         self.updater.start_polling()

hosts/telebot/src/bot/config.py

@@ -8,3 +8,5 @@
 
 TELEMSG_API_HOST = os.environ.get('TELEMSG_API_HOST', 'localhost')
 TELEMSG_API_PORT = os.environ.get('TELEMSG_API_PORT', 5001)
+
+TELEGRAM_ADMIN_ID = int(os.environ['TELEGRAM_ADMIN_ID'])

hosts/telebot/src/bot/handlers/message.py

@@ -0,0 +1,34 @@
+import os
+import re
+
+import requests
+from telegram.ext import Filters, MessageHandler
+
+from ..config import TELEGRAM_ADMIN_ID, TELEMSG_API_HOST, TELEMSG_API_PORT
+from .logging import logger
+
+
+def admin_message_handler(update, context):
+    if update.message.chat_id != TELEGRAM_ADMIN_ID:
+        return
+    if update.message.reply_to_message is None:
+        return
+
+    text = update.message.reply_to_message.text
+    m = re.match(r'Message from (\d+):', text)
+    if m is None:
+        return
+    target_user = int(m.group(1))
+    text = f'Message from admin:\n{update.message.text}'
+    message_user(target_user, text)
+
+
+def message_user(chat_id: int, text: str) -> None:
+    url = f'http://{TELEMSG_API_HOST}:{TELEMSG_API_PORT}/message'
+    requests.post(url, json={
+        'chat_id': chat_id,
+        'text': text,
+    })
+
+
+message_handler = MessageHandler(Filters.text & ~Filters.command, admin_message_handler)