Refactor FastAPI server configuration and improve config handling

api_server.py

@@ -1,23 +1,29 @@
+import logging
+import json
+
+from contextlib import asynccontextmanager
 from fastapi import FastAPI, HTTPException, Response
 from fastapi.responses import HTMLResponse
 from telegram_client import TelegramClient
 from config import get_settings
-import logging
-import json
 
 logger = logging.getLogger(__name__)
-app = FastAPI(title="PyroTg Bridge")
 client = TelegramClient()
 settings = get_settings()
 
-@app.on_event("startup")
-async def startup():
+@asynccontextmanager
+async def lifespan(_: FastAPI):
+    # Startup
     await client.start()
-
-@app.on_event("shutdown")
-async def shutdown():
+    yield
+    # Shutdown
     await client.stop()
 
+app = FastAPI(
+    title="PyroTg Bridge",
+    lifespan=lifespan
+)
+
 @app.get("/html/{channel}/{post_id}", response_class=HTMLResponse)
 async def get_post_html(channel: str, post_id: int):
     try:
@@ -32,7 +38,7 @@ async def get_post_html(channel: str, post_id: int):
         return post["html"]
     except Exception as e:
         logger.error(f"HTML endpoint error: {str(e)}")
-        raise HTTPException(status_code=500, detail=str(e))
+        raise HTTPException(status_code=500, detail=str(e)) from e
 
 @app.get("/json/{channel}/{post_id}")
 async def get_post(channel: str, post_id: int):

config.py

@@ -2,19 +2,12 @@ import os
 
 TG_API_ID = int(os.getenv("TG_API_ID"))
 TG_API_HASH = os.getenv("TG_API_HASH")
-SESSION_PATH = os.getenv("SESSION_PATH", "session.file")
+SESSION_PATH = os.getenv("SESSION_PATH", "session.file") or "session.file"
 API_HOST = os.getenv("API_HOST", "0.0.0.0")
-API_PORT = int(os.getenv("API_PORT", 8000))
-REQUEST_TIMEOUT = int(os.getenv("REQUEST_TIMEOUT", 30))
+API_PORT = int(os.getenv("API_PORT") or 8000)
+REQUEST_TIMEOUT = int(os.getenv("REQUEST_TIMEOUT") or 30)
 SESSION_STRING = os.getenv("TG_SESSION_STRING", "")
 
-DEFAULT_CONFIG = {
-    "session_string": "",
-    "tg_api_id": 12345,
-    "tg_api_hash": "xxxxxxxx",
-    "file_access_flags": ["can_access_files"]
-}
-
 def get_settings():
     return {
         "tg_api_id": TG_API_ID,