feat(twitch): Add authentication server.

src/twitch/authserver.py

@@ -1,7 +1,86 @@
-"""
-We want to open an aiohttp server and listen on a configured port.
-When we get a request, we validate it to be 'of twitch form',
-parse out the error or access token, state, etc, and then pass that information on.
+import logging
+import uuid
+import asyncio
+from contextvars import ContextVar
 
-Passing on maybe done through webhook server?
-"""
+import aiohttp
+from aiohttp import web
+
+logger = logging.getLogger(__name__)
+reqid: ContextVar[str] = ContextVar('reqid', default='ROOT')
+
+
+class AuthServer:
+    def __init__(self):
+        self.listeners = {}
+
+    async def handle_twitch_callback(self, request: web.Request) -> web.StreamResponse:
+        args = request.query
+        if 'state' not in args:
+            raise web.HTTPBadRequest(text="No state provided.")
+        if args['state'] not in self.listeners:
+            raise web.HTTPBadRequest(text="Invalid state.")
+        self.listeners[args['state']].set_result(dict(args))
+        return web.Response(text="Authorisation complete! You may now close this page and return to the application.")
+
+    async def handle_listen_request(self, request: web.Request) -> web.StreamResponse:
+        _reqid = str(uuid.uuid1())
+        reqid.set(_reqid)
+
+        logger.debug(f"[reqid: {_reqid}] Received websocket listen connection: {request!r}")
+
+        ws = web.WebSocketResponse()
+        await ws.prepare(request)
+
+        # Get the listen request data
+        try:
+            listen_req = await ws.receive_json(timeout=60)
+            logger.info(f"[reqid: {_reqid}] Received websocket listen request: {request}")
+            if 'state' not in listen_req:
+                logger.error(f"[reqid: {_reqid}] Websocket listen request is missing state, cancelling.")
+                raise web.HTTPBadRequest(text="Listen request must include state string.")
+            elif listen_req['state'] in self.listeners:
+                logger.error(f"[reqid: {_reqid}] Websocket listen request with duplicate state, cancelling.")
+                raise web.HTTPBadRequest(text="Invalid state string.")
+        except ValueError:
+            logger.exception(f"[reqid: {_reqid}] Listen request could not be parsed to JSON.")
+            raise web.HTTPBadRequest(text="Request must be a JSON formatted string.")
+        except TypeError:
+            logger.exception(f"[reqid: {_reqid}] Listen request was binary not JSON.")
+            raise web.HTTPBadRequest(text="Request must be a JSON formatted string.")
+        except asyncio.TimeoutError:
+            logger.info(f"[reqid: {_reqid}] Timed out waiting for listen request data.")
+            raise web.HTTPRequestTimeout(text="Request must be a JSON formatted string.")
+        except Exception:
+            logger.exception(f"[reqid: {_reqid}] Unknown exception.")
+            raise web.HTTPInternalServerError()
+
+        try:
+            fut = self.listeners[listen_req['state']] = asyncio.Future()
+            result = await asyncio.wait_for(fut, timeout=120)
+        except asyncio.TimeoutError:
+            logger.info(f"[reqid: {_reqid}] Timed out waiting for auth callback from Twitch, closing.")
+            raise web.HTTPGatewayTimeout(text="Did not receive an authorisation code from Twitch in time.")
+        finally:
+            self.listeners.pop(listen_req['state'], None)
+
+        logger.debug(f"[reqid: {_reqid}] Responding with auth result {result}.")
+        await ws.send_json(result)
+        await ws.close()
+        logger.debug(f"[reqid: {_reqid}] Request completed handling.")
+
+        return ws
+
+def main(argv):
+    app = web.Application()
+    server = AuthServer()
+    app.router.add_get("/twiauth/confirm", server.handle_twitch_callback)
+    app.router.add_get("/twiauth/listen", server.handle_listen_request)
+
+    logger.info("App setup and configured. Starting now.")
+    web.run_app(app, port=int(argv[1]) if len(argv) > 1 else 8080)
+
+
+if __name__ == '__main__':
+    import sys
+    main(sys.argv)