Function useCanWrite

react/src/hooks.ts:461–496

(
  resource: Resource,
  agent?: string,
)

 * don't explicitly pass an Agent URL, it will select the current Agent set by the store.
 */
export function useCanWrite(
  resource: Resource,
  agent?: string,
): [canWrite: boolean | null, message: string] {
  const store = useStore();
  const [canWrite, setCanWrite] = useState<boolean | null>(null);
  const [msg, setMsg] = useState<string | null>(null);
  const agentStore = store.getAgent();

  // If the subject changes, make sure to change the resource!
  useEffect(() => {
    if (agent == undefined) {
      agent = agentStore?.subject;
    }
    if (agent == undefined) {
      setMsg('No Agent set');
      setCanWrite(false);
      return;
    }
    setMsg('Checking write rights...');
    async function tryCanWrite() {
      const [canWriteAsync, msg] = await resource.canWrite(store, agent);
      setCanWrite(canWriteAsync);
      if (canWriteAsync) {
        setMsg(null);
      } else {
        setMsg(
          "You don't have write rights in this resource or its parents: " + msg,
        );
      }
    }
    tryCanWrite();
  }, [resource, agent, agentStore?.subject]);

  return [canWrite, msg];
}

/**
 * The context must be provided by wrapping a high level React element in