feat: web UI chat render, panels, presence + analytics

backend/src/api/realtime.py

@@ -0,0 +1,123 @@
+import asyncio
+import json
+import logging
+from typing import Any
+
+import asyncpg
+
+from utils.env import env
+from utils.events import BG_EVENTS_CHANNEL
+from utils.read import chats as chats_read
+from utils.read import presence as presence_read
+
+logger = logging.getLogger(__name__)
+
+QUEUE_MAXSIZE = 256
+
+
+class Subscriber:
+    def __init__(self, account_id: int, chat_id: int | None) -> None:
+        self.account_id = account_id
+        self.chat_id = chat_id
+        self.queue: asyncio.Queue[dict[str, Any]] = asyncio.Queue(maxsize=QUEUE_MAXSIZE)
+
+
+class EventHub:
+    def __init__(self) -> None:
+        self._subscribers: set[Subscriber] = set()
+        self._pool: asyncpg.Pool | None = None
+        self._conn: asyncpg.Connection | None = None
+        self._tasks: set[asyncio.Task] = set()
+
+    def subscribe(self, account_id: int, chat_id: int | None) -> Subscriber:
+        sub = Subscriber(account_id, chat_id)
+        self._subscribers.add(sub)
+        return sub
+
+    def unsubscribe(self, sub: Subscriber) -> None:
+        self._subscribers.discard(sub)
+
+    async def start(self, pool: asyncpg.Pool) -> None:
+        self._pool = pool
+        conn = await asyncpg.connect(dsn=env.db.connection_url)
+        await conn.add_listener(BG_EVENTS_CHANNEL, self._on_notify)
+        self._conn = conn
+        logger.info("Realtime hub listening on %s", BG_EVENTS_CHANNEL)
+
+    async def stop(self) -> None:
+        for task in self._tasks:
+            task.cancel()
+        if self._conn is not None:
+            await self._conn.close()
+            self._conn = None
+
+    def _on_notify(
+        self, _conn: asyncpg.Connection, _pid: int, _channel: str, payload: str
+    ) -> None:
+        task = asyncio.create_task(self._dispatch(payload))
+        self._tasks.add(task)
+        task.add_done_callback(self._tasks.discard)
+
+    async def _dispatch(self, payload: str) -> None:
+        try:
+            event = json.loads(payload)
+        except json.JSONDecodeError:
+            return
+        account_id = event.get("account_id")
+        chat_id = event.get("chat_id")
+        targets = [
+            sub
+            for sub in self._subscribers
+            if sub.account_id == account_id
+            and (sub.chat_id is None or sub.chat_id == chat_id)
+        ]
+        if not targets:
+            return
+        frame = await self._build_frame(event)
+        if frame is None:
+            return
+        for sub in targets:
+            try:
+                sub.queue.put_nowait(frame)
+            except asyncio.QueueFull:
+                logger.warning("Dropping event for slow subscriber")
+
+    async def _build_frame(  # noqa: PLR0911
+        self, event: dict[str, Any]
+    ) -> dict[str, Any] | None:
+        if self._pool is None:
+            return None
+        kind = event.get("kind")
+        account_id = event["account_id"]
+        if kind in {"message", "edit", "reaction"}:
+            view = await chats_read.get_message(
+                self._pool, account_id, event["chat_id"], event["message_id"]
+            )
+            if view is None:
+                return None
+            return {"type": kind, "message": view.model_dump(mode="json")}
+        if kind == "delete":
+            return {
+                "type": "delete",
+                "chat_id": event.get("chat_id"),
+                "message_ids": event.get("message_ids", []),
+            }
+        if kind == "presence":
+            sample = await presence_read.current_presence(
+                self._pool, account_id, event["chat_id"]
+            )
+            return {
+                "type": "presence",
+                "peer_id": event["chat_id"],
+                "sample": sample.model_dump(mode="json") if sample else None,
+            }
+        if kind == "receipt":
+            return {
+                "type": "receipt",
+                "chat_id": event["chat_id"],
+                "read_up_to": event["message_id"],
+            }
+        return None
+
+
+hub = EventHub()