Migrated Hosted Explorer to React (#360)

Co-authored-by: Victor Meng <vimeng@microsoft.com>
Co-authored-by: Steve Faulkner <stfaul@microsoft.com>

src/hooks/useSubscriptions.tsx

@@ -0,0 +1,40 @@
+import { Subscription } from "../Contracts/DataModels";
+import useSWR from "swr";
+
+interface SubscriptionListResult {
+  nextLink: string;
+  value: Subscription[];
+}
+
+export async function fetchSubscriptions(accessToken: string): Promise<Subscription[]> {
+  const headers = new Headers();
+  const bearer = `Bearer ${accessToken}`;
+
+  headers.append("Authorization", bearer);
+
+  let subscriptions: Array<Subscription> = [];
+  let nextLink = `https://management.azure.com/subscriptions?api-version=2020-01-01`;
+
+  while (nextLink) {
+    const response = await fetch(nextLink, { headers });
+    const result: SubscriptionListResult =
+      response.status === 204 || response.status === 304 ? undefined : await response.json();
+    if (!response.ok) {
+      throw result;
+    }
+    nextLink = result.nextLink;
+    const validSubscriptions = result.value.filter(
+      sub => sub.state === "Enabled" || sub.state === "Warned" || sub.state === "PastDue"
+    );
+    subscriptions = [...subscriptions, ...validSubscriptions];
+  }
+  return subscriptions;
+}
+
+export function useSubscriptions(armToken: string): Subscription[] | undefined {
+  const { data } = useSWR(
+    () => (armToken ? ["subscriptions", armToken] : undefined),
+    (_, armToken) => fetchSubscriptions(armToken)
+  );
+  return data;
+}