refactor(k8s): namespace core logic (#12142)

Co-authored-by: testA113 <aliharriss1995@gmail.com>
Co-authored-by: Anthony Lapenna <anthony.lapenna@portainer.io>
Co-authored-by: James Carppe <85850129+jamescarppe@users.noreply.github.com>
Co-authored-by: Ali <83188384+testA113@users.noreply.github.com>

app/react/kubernetes/dashboard/queries/getNamespacesCountQuery.ts

@@ -0,0 +1,41 @@
+import { useQuery } from '@tanstack/react-query';
+
+import { withError } from '@/react-tools/react-query';
+import axios, { parseAxiosError } from '@/portainer/services/axios';
+import { EnvironmentId } from '@/react/portainer/environments/types';
+
+const queryKeys = {
+  list: (environmentId: EnvironmentId) =>
+    ['environments', environmentId, 'dashboard', 'namespacesCount'] as const,
+};
+
+export function useGetNamespacesCountQuery(
+  environmentId: EnvironmentId,
+  options?: { autoRefreshRate?: number }
+) {
+  return useQuery(
+    queryKeys.list(environmentId),
+    async () => getNamespacesCount(environmentId),
+    {
+      ...withError('Unable to get namespaces count'),
+      refetchInterval() {
+        return options?.autoRefreshRate ?? false;
+      },
+    }
+  );
+}
+
+async function getNamespacesCount(environmentId: EnvironmentId) {
+  try {
+    const { data: namespacesCount } = await axios.get<number>(
+      `kubernetes/${environmentId}/namespaces/count`
+    );
+
+    return namespacesCount;
+  } catch (e) {
+    throw parseAxiosError(
+      e,
+      'Unable to get dashboard stats. Some counts may be inaccurate.'
+    );
+  }
+}