Lazy load database offer in data explorer (#208)

Co-authored-by: zfoster <notzachfoster@gmail.com>

src/Common/dataAccess/readOffers.ts

@@ -0,0 +1,36 @@
+import { Offer } from "../../Contracts/DataModels";
+import { ClientDefaults } from "../Constants";
+import { MessageTypes } from "../../Contracts/ExplorerContracts";
+import { Platform, configContext } from "../../ConfigContext";
+import { client } from "../CosmosClient";
+import { sendCachedDataMessage } from "../MessageHandler";
+import { userContext } from "../../UserContext";
+
+export const readOffers = async (isServerless?: boolean): Promise<Offer[]> => {
+  if (isServerless) {
+    return []; // Reading offers is not supported for serverless accounts
+  }
+
+  try {
+    if (configContext.platform === Platform.Portal) {
+      return sendCachedDataMessage<Offer[]>(MessageTypes.AllOffers, [
+        userContext.databaseAccount.id,
+        ClientDefaults.portalCacheTimeoutMs
+      ]);
+    }
+  } catch (error) {
+    // If error getting cached Offers, continue on and read via SDK
+  }
+
+  return client()
+    .offers.readAll()
+    .fetchAll()
+    .then(response => response.resources)
+    .catch(error => {
+      // This should be removed when we can correctly identify if an account is serverless when connected using connection string too.
+      if (error.message.includes("Reading or replacing offers is not supported for serverless accounts")) {
+        return [];
+      }
+      throw error;
+    });
+};