add utils for jotai atoms

src/app/state/utils.ts

@@ -0,0 +1,55 @@
+import { SetStateAction } from 'jotai';
+import { ClientEvent, MatrixClient, Room, RoomEvent } from 'matrix-js-sdk';
+import { Membership } from '../../types/matrix/room';
+import { disposable } from '../utils/disposable';
+
+export const atomRoomsWithMemberships = disposable(
+  (
+    setAtom: (update: SetStateAction<string[]>) => void,
+    mx: MatrixClient,
+    memberships: Membership[]
+  ) => {
+    const satisfyMembership = (room: Room): boolean =>
+      !!memberships.find((membership) => membership === room.getMyMembership());
+
+    setAtom(
+      mx
+        .getRooms()
+        .filter(satisfyMembership)
+        .map((room) => room.roomId)
+    );
+
+    const updateAtom = (type: 'PUT' | 'DELETE', roomId: string) => {
+      setAtom((ids) => {
+        const newIds = ids.filter((id) => id !== roomId);
+        if (type === 'PUT') newIds.push(roomId);
+        return newIds;
+      });
+    };
+
+    const handleAddRoom = (room: Room) => {
+      if (satisfyMembership(room)) {
+        updateAtom('PUT', room.roomId);
+      }
+    };
+
+    const handleMembershipChange = (room: Room) => {
+      if (!satisfyMembership(room)) {
+        updateAtom('DELETE', room.roomId);
+      }
+    };
+
+    const handleDeleteRoom = (roomId: string) => {
+      updateAtom('DELETE', roomId);
+    };
+
+    mx.on(ClientEvent.Room, handleAddRoom);
+    mx.on(RoomEvent.MyMembership, handleMembershipChange);
+    mx.on(ClientEvent.DeleteRoom, handleDeleteRoom);
+    return () => {
+      mx.removeListener(ClientEvent.Room, handleAddRoom);
+      mx.removeListener(RoomEvent.MyMembership, handleMembershipChange);
+      mx.removeListener(ClientEvent.DeleteRoom, handleDeleteRoom);
+    };
+  }
+);