adding back msal

Author: kitttang

runner/src/server/services/msalAuthorizerService.ts

@@ -0,0 +1,26 @@
+import { ConfidentialClientApplication } from "@azure/msal-node";
+import { MsalAuthorizerConfig } from "@xgovformbuilder/model";
+
+export class MsalAuthorizer {
+  private readonly msal: ConfidentialClientApplication;
+  private readonly scopes: string[];
+
+  constructor(config: MsalAuthorizerConfig) {
+    this.scopes = config.scopes;
+    this.msal = new ConfidentialClientApplication({
+      auth: {
+        clientId: config.clientId,
+        clientSecret: config.clientSecret,
+        authority: `https://login.microsoftonline.com/${config.tenantId}`,
+      },
+    });
+  }
+
+  async getToken(): Promise<string> {
+    const token = await this.msal.acquireTokenByClientCredential({
+      scopes: this.scopes,
+    });
+    if (!token?.accessToken) throw new Error("Failed to acquire access token");
+    return token.accessToken;
+  }
+}