Initial MCM project: FastAPI + Textual TUI unified messenger

MultiCustomerMessenger supporting Telegram (python-telegram-bot),
WhatsApp (Green API) and SMS (python-gsmmodem-new). REST API with
Bearer-token auth, SQLAlchemy models for MariaDB, APScheduler for
background polling, and Textual TUI running in same asyncio event-loop.

channels/telegram_channel.py

@@ -0,0 +1,112 @@
+from __future__ import annotations
+
+import asyncio
+import logging
+from typing import TYPE_CHECKING, Any, Callable, Awaitable
+
+from telegram import Update
+from telegram.ext import Application, ApplicationBuilder, MessageHandler, filters
+
+from channels.base import BaseChannel
+from config import settings
+
+if TYPE_CHECKING:
+    pass
+
+logger = logging.getLogger(__name__)
+
+
+class TelegramChannel(BaseChannel):
+    """Telegram-Kanal via python-telegram-bot (Long-Polling)."""
+
+    def __init__(self) -> None:
+        self._app: Application | None = None
+        self._inbound_callback: Callable[[dict[str, Any]], Awaitable[None]] | None = None
+
+    def set_inbound_callback(self, cb: Callable[[dict[str, Any]], Awaitable[None]]) -> None:
+        """Callback, der bei eingehenden Nachrichten aufgerufen wird."""
+        self._inbound_callback = cb
+
+    # ── BaseChannel interface ──────────────────────────────────────────────────
+
+    async def send_message(
+        self,
+        recipient: str,
+        text: str,
+        reply_to_id: str | None = None,
+    ) -> dict[str, Any]:
+        if not self._app:
+            return {"success": False, "channel_message_id": None, "error": "Telegram not initialized"}
+        try:
+            kwargs: dict[str, Any] = {"chat_id": recipient, "text": text}
+            if reply_to_id:
+                kwargs["reply_to_message_id"] = int(reply_to_id)
+            msg = await self._app.bot.send_message(**kwargs)
+            return {"success": True, "channel_message_id": str(msg.message_id), "error": None}
+        except Exception as exc:
+            logger.error("Telegram send error: %s", exc)
+            return {"success": False, "channel_message_id": None, "error": str(exc)}
+
+    async def check_connection(self) -> tuple[bool, str]:
+        if not self._app:
+            return False, "Not initialized"
+        try:
+            me = await self._app.bot.get_me()
+            return True, f"@{me.username}"
+        except Exception as exc:
+            return False, str(exc)
+
+    async def start(self) -> None:
+        if not settings.telegram_enabled:
+            logger.info("Telegram disabled (no token configured)")
+            return
+
+        self._app = ApplicationBuilder().token(settings.telegram_token).build()
+        self._app.add_handler(MessageHandler(filters.TEXT & ~filters.COMMAND, self._handle_message))
+        self._app.add_handler(MessageHandler(filters.PHOTO | filters.DOCUMENT | filters.VOICE, self._handle_message))
+
+        await self._app.initialize()
+        await self._app.start()
+        # Long-Polling als Background-Task
+        asyncio.create_task(self._polling_loop(), name="telegram-polling")
+        logger.info("Telegram channel started (long-polling)")
+
+    async def stop(self) -> None:
+        if self._app:
+            await self._app.stop()
+            await self._app.shutdown()
+            logger.info("Telegram channel stopped")
+
+    # ── Interner Handler ───────────────────────────────────────────────────────
+
+    async def _polling_loop(self) -> None:
+        """Endlos-Polling im Hintergrund."""
+        try:
+            await self._app.updater.start_polling(allowed_updates=["message"])
+            # Warte bis gestoppt
+            await self._app.updater.idle()
+        except asyncio.CancelledError:
+            pass
+        except Exception as exc:
+            logger.error("Telegram polling error: %s", exc)
+
+    async def _handle_message(self, update: Update, context: Any) -> None:
+        if not update.message or not self._inbound_callback:
+            return
+        msg = update.message
+        payload: dict[str, Any] = {
+            "channel": "telegram",
+            "channel_message_id": str(msg.message_id),
+            "sender_telegram_id": str(msg.from_user.id) if msg.from_user else None,
+            "sender_name": (
+                (msg.from_user.full_name or msg.from_user.username)
+                if msg.from_user
+                else "Unknown"
+            ),
+            "chat_id": str(msg.chat.id),
+            "text": msg.text or msg.caption or "",
+            "reply_to_id": (
+                str(msg.reply_to_message.message_id) if msg.reply_to_message else None
+            ),
+        }
+        await self._inbound_callback(payload)