Refactor of authentication code. Added configuration file selectable authentication method. Selectable from built-in Azure Identity, and custom PCA using MSAL.

src/graph/auth.ts

@@ -1,24 +1,54 @@
 // SPDX-License-Identifier: MIT
 
 import { Client } from "@microsoft/microsoft-graph-client";
-import { acquireResourceToken } from "../azure/index.ts";
+import { getAccessToken } from "../azure/index.ts";
+import { DefaultAzureCredential, getBearerTokenProvider } from "@azure/identity";
 
-type GraphApiToken = {
-  accessToken: string;
-  [key: string]: unknown;
-};
+// export async function getGraphClientUsingMsal(
+//   tenantId: string,
+//   clientId: string,
+// ): Promise<Client> {
+//   const graphApiToken = await getAccessToken(tenantId, clientId, ["graph"]);
 
-export async function getGraphClient(
+//   return Client.init({
+//     authProvider: (done) => {
+//       done(null, graphApiToken);
+//     },
+//   });
+// }
+
+type GraphAuthProvider = (
+  done: (error: Error | null, accessToken: string | null) => void
+) => void;
+
+export function getMsalAuthProvider(
   tenantId: string,
   clientId: string,
-): Promise<{ graphApiToken: GraphApiToken; client: any }> {
-  const graphApiToken = await acquireResourceToken(tenantId, clientId, "graph") as GraphApiToken;
+): GraphAuthProvider {
+  return (done) => {
+    void getAccessToken(tenantId, clientId, ["graph"])
+      .then((accessToken) => done(null, accessToken))
+      .catch((err) => done(err as Error, null));
+  };
+}
 
-  const client = Client.init({
-    authProvider: (done) => {
-      done(null, graphApiToken.accessToken);
-    },
+export function getAzureIdentityAuthProvider(
+  tenantId: string,
+  clientId: string,
+) {
+  const credential = new DefaultAzureCredential({
+    tenantId,
+    managedIdentityClientId: clientId,
   });
 
-  return { graphApiToken, client };
+  const getBearerToken = getBearerTokenProvider(
+    credential,
+    "https://graph.microsoft.com/.default",
+  );
+
+  return (done: (error: Error | null, accessToken: string | null) => void) => {
+    void getBearerToken()
+      .then((token) => done(null, token))
+      .catch((err) => done(err as Error, null));
+  };
 }

src/graph/index.ts

@@ -3,3 +3,22 @@
 export * from "./auth.ts";
 export * from "./app.ts";
 export * from "./sp.ts";
+
+import { loadAuthConfig, loadConfig } from "../index.ts";
+import { Client } from "@microsoft/microsoft-graph-client";
+
+import { getMsalAuthProvider, getAzureIdentityAuthProvider } from "./auth.ts";
+
+export async function getGraphClient(): Promise<Client> {
+  const config = await loadConfig();
+
+  const authConfig = await loadAuthConfig("public-config");
+  const authProvider =
+    config.authMode === "azure-identity"
+      ? getAzureIdentityAuthProvider(authConfig.tenantId, authConfig.clientId)
+      : getMsalAuthProvider(authConfig.tenantId, authConfig.clientId);
+
+  return Client.init({
+    authProvider: authProvider,
+  });
+}