Revert "[lib] Rip useShouldShowDisconnectedBar and `useDisconnected…

…Bar` out of `hooks/disconnected-bar`"

This reverts commit 7f64f3d.

lib/hooks/disconnected-bar.js

@@ -66,4 +66,52 @@ function useDisconnectedBarVisibilityHandler(networkConnected: boolean): void {
   }, [connectionStatus, someRequestIsLate, setDisconnected]);
 }
 
-export { useDisconnectedBarVisibilityHandler };
+function useShouldShowDisconnectedBar(): {
+  +disconnected: boolean,
+  +shouldShowDisconnectedBar: boolean,
+} {
+  const connection = useSelector(connectionSelector(ashoatKeyserverID));
+  invariant(connection, 'keyserver missing from keyserverStore');
+  const disconnected = connection.showDisconnectedBar;
+  const socketConnected = connection.status === 'connected';
+
+  const shouldShowDisconnectedBar = disconnected || !socketConnected;
+  return { disconnected, shouldShowDisconnectedBar };
+}
+
+type DisconnectedBarCause = 'connecting' | 'disconnected';
+
+function useDisconnectedBar(
+  changeShowing: boolean => void,
+): DisconnectedBarCause {
+  const { disconnected, shouldShowDisconnectedBar } =
+    useShouldShowDisconnectedBar();
+
+  const prevShowDisconnectedBar = React.useRef<?boolean>();
+  React.useEffect(() => {
+    const wasShowing = prevShowDisconnectedBar.current;
+    if (shouldShowDisconnectedBar && wasShowing === false) {
+      changeShowing(true);
+    } else if (!shouldShowDisconnectedBar && wasShowing) {
+      changeShowing(false);
+    }
+    prevShowDisconnectedBar.current = shouldShowDisconnectedBar;
+  }, [shouldShowDisconnectedBar, changeShowing]);
+
+  const [barCause, setBarCause] =
+    React.useState<DisconnectedBarCause>('connecting');
+  React.useEffect(() => {
+    if (shouldShowDisconnectedBar && disconnected) {
+      setBarCause('disconnected');
+    } else if (shouldShowDisconnectedBar) {
+      setBarCause('connecting');
+    }
+  }, [shouldShowDisconnectedBar, disconnected]);
+  return barCause;
+}
+
+export {
+  useDisconnectedBarVisibilityHandler,
+  useShouldShowDisconnectedBar,
+  useDisconnectedBar,
+};